GLERL Publication Abstracts: FY 2008

Capitalized names represent GLERL authors.


Arhonditsis, G.B., S.S. Qian, C.A. STOW, E.C. Lamon, and K.H. Reckhow. Eutrophication risk assessment using Bayesian calibration of process-based models: Application to a mesotrophic lake. Ecological Modelling 208:215-229 (2007).

We introduce the Bayesian calibration of process-based models to address the urgent need for robust modeling tools that can effectively support environmental management. The proposed framework aims to combine the advantageous features of both mechanistic and statistical approaches. Models that are based on mechanistic understanding yet remain within the bounds of data-based parameter estimation can accommodate rigorous and complete error analysis. The incorporation of mechanism improves the confidence in predictions made for a variety of conditions, while the statistical methods provide an empirical basis for parameter estimation and allow for estimates of predictive uncertainty. Our illustration focuses on eutrophication modeling but the proposed methodological framework can be easily transferred to a wide variety of disciplines (e.g., hydrology, ecotoxicology, air pollution). We examine the advantages of the Bayesian calibration using a four state variable (phosphate–detritus–phytoplankton–zooplankton) model and the mesotrophic Lake Washington (Washington State, USA) as a case study. Prior parameter distributions were formed on the basis of literature information, while Markov chain Monte Carlo simulations provided a convenient means for approximating the posterior parameter distributions. The model reproduces the key epilimnetic temporal patterns of the system and provides realistic estimates of predictive uncertainty for water quality variables of environmental interest. Finally, we highlight the benefits of Bayesian parameter estimation, such as the quantification of uncertainty in model predictions, optimization of the sampling design of monitoring programs using value of information concepts from decision theory, alignment with the policy practice of adaptive management, and expression of model outputs as probability distributions, that are perfectly suited for stakeholders and policy makers when making decisions for sustainable environmental management.

Arhonditsis, G.B., C.A. STOW, H.W. Paerl, L.M. Valdes-Weaver, L.J. Steinberg, and K.H. Reckhow. Delineation of the role of nutrient dynamics and hydrologic forcing on phytoplankton patterns along a freshwater-marine continuum. Ecological Modelling 208:230-246 (2008).

We examined the spatiotemporal phytoplankton community patterns and identified the nature of the underlying causal mechanisms in a freshwater–saltwater continuum, the Neuse River Estuary (North Carolina, USA). We used a Bayesian structural equation modeling (SEM) approach that considers the regulatory role of the physical environment (flow, salinity, and light availability), nitrogen (dissolved oxidized inorganic nitrogen and total dissolved inorganic nitrogen), phosphorus, and temperature on total phytoplankton biomass and phytoplankton community composition. Hydrologic forcing (mainly the river flow fluctuations) dominates the up-estuary processes and loosens the coupling between nutrients and phytoplankton. The switch from an upstream negative to a downstream positive phytoplankton–physical environment relationship suggests that the elevated advective transport from the upper reaches of the estuary leads to a phytoplankton biomass accumulation in the mid- and down-estuary segments. The positive influence of the physical environment on the phytoplankton community response was more evident on diatom, chlorophyte and cryptophyte dynamics, which also highlights the opportunistic behavior of these taxa (faster nutrient uptake and growth rates, tolerance on low salinity conditions) that allows them to dominate the phytoplankton community during high freshwater conditions. Model results highlight the stronger association between phosphorus and total phytoplankton dynamics at the upstream freshwater locations; both nitrogen and phosphorus played a significant role in the middle section of the estuary, while the nitrogen–phytoplankton relationship was stronger in the downstream meso-polyhaline zone. Finally, our analysis provided evidence of a protracted favorable environment (e.g., longer residence times, low DIN concentrations and relaxation of the phosphorus limitation) for cyanobacteria dominance as we move to the down-estuary area, resulting in structural shifts on the phytoplankton community temporal patterns.

ASSEL, R.A. Indicator: Lake Erie ice cover. In State of the Strait: Status and Trends of Key Indicators. J.H. Hartig, M.A. Zarull, J.H. Ciborowski, J.E. Gannon, E. Wilke, G. Norwood, and A. Vincent (Eds.). Great Lakes Institute for Environmental Research, Occasional Publication No. 5, University of Windsor, Ontario, Canada, pp. 102-104 (2007).

Winter ice cover on Lake Erie affects the amount of heat and moisture transferred between the lake and the atmosphere. During winter, ice and snow can decrease the amount of light available below the ice surface for photosynthesis. In the absence of an ice cover, winds can cause mixing of the water column and in some cases resuspend bottom sediment. If ice cover is present, high winds can cause rafting of ice that sometimes causes ice-scouring along the lake bottom. In the nearshore region, erosion can occur when ice attached to the shore is moved by winds. Ice cover also affects lake levels by reducing lake evaporation. Ice cover can impact the economy by impeding or stopping navigation, interfering with power plants and cooling water intakes, and damaging shore structures. Potential economic impacts of reduced ice cover could include a longer shipping season, increased evaporation, lower lake levels, increased dredging for navigation, lower ship cargo capacity, reduced winter recreational activities such as ice fishing, and loss of critical habitats. Winter ice formation and seasonal ice cycles have been documented over the past 43 winters through visual observation, radar, and satellites.

BELETSKY, D., D.M. MASON, D.J. SCHWAB, E.S. Rutherford, J.J. Janssen, D.F. Clapp, and J.M. Dettmers. Biophysical model of larval yellow perch advection and settlement in Lake Michigan. Journal of Great Lakes Research 33:842-866 (2007).

Potential for large-scale physical transport processes to affect recruitment of Lake Michigan yellow perch (Perca flavescens) was studied by examining the variation in larval distribution, growth rate, and settlement during June–August 1998–2003 using a 3D particle transport model linked with an individual-based bioenergetics growth model. In all years, virtual larvae were released nearshore in southwestern Lake Michigan, a known and important spawning region for yellow perch. For any given year, the same circulation pattern and water temperature either promoted or reduced yellow perch settlement depending on the consumption rates and settlement size chosen in the growth model. Increased consumption increased the number of settled larvae and expanded the total area where larvae settled, whereas increased settlement size reduced the number of settled larvae and reduced the overall settlement area. Interannual variability in circulation patterns and water temperature also resulted in contrasting larval settlement rates, settlement locations, and size of settlement areas between years. Model predictions were most consistent with field observations of age-0 yellow perch from Illinois and Michigan waters when settlement was assumed to occur at 50 mm. Moreover, our model suggests that larvae originating from southwestern Lake Michigan can recruit anywhere within the southern basin and even in the northern basin. Future model improvement will require information on the relative contribution of various sectors to the larval pool, their distribution with reference to the hydrodynamic landscape, the feeding and growth of yellow perch during their pelagic phase, and the size at transition to demersal stage.

Costantini, M., S.A. LUDSIN, D.M. MASON, X. Zhang, W.C. Boicourt, and S.B. BRANDT. Effect of hypoxia on habitat quality of striped bass (Morone saxatilis) in Chesapeake Bay. Canadian Journal of Fisheries and Aquatic Sciences 65:989-1002 (2008).

Eutrophication-induced hypoxia may affect both benthic and pelagic organisms in coastal systems. To evaluate the effect of hypoxia on pelagic striped bass (Morone saxatilis), we quantified the growth rate potential (GRP) of age-2 and age-4 fish in Chesapeake Bay during 1996 and 2000 using observed temperature, dissolved oxygen, and prey abundance information in a spatially-explicit bioenergetics modeling framework. Regions of the Bay with bottom hypoxia were generally areas with high quality habitat (i.e., GRP > 0 g⋅g-1⋅day-1), primarily because prey fish were forced into warm, oxygenated surface waters suitable for striped bass foraging and growth. In turn, by concentrating fish prey above the oxycline and removing bottom waters as a refuge, hypoxia likely enhanced striped bass predation efficiency and continued to the recovery of striped bass during the mid-1990s, a time when the striped bass fishery also was closed. This short-term positive effect of hypoxia on striped bass, however, appears to have been counterbalanced by a long-term negative effect of hypoxia in recent years. Ultimately, hypoxia-enhanced operation efficiency, combined with an abundance of striped bass due to restricted harvest, appears to be causing overconsumption of prey fishes in Chesapeake Bay, thus helping to explain poor growth and health of striped bass in recent years.

CROLEY, T.E. II. The once-Great Lakes. Proceedings, Climate Change in the Great Lakes Region, Starting a Public Discussion, Green Bay, WI, March 2007. University of Wisconsin Sea Grant Institute, pp. 65-69 (2008).

This presentation reviewed the results of a study of hydrological effects of climate change in the Great Lakes region conducted by the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory. To establish a climate baseline, researchers collected daily precipitation and maximum-minimum air temperature data for 1948-99 from 1,800 meteorological stations around the Great Lakes, and temperature, wind speed, humidity, and cloud cover over the lakes from 40 stations. Using these data to represent present climate conditions, three different general circulation models were used to simulate four future climate scenarios: "warmer and dry," "hot and dry," "warmer and wet," and "hot and wet." This enabled the scientists to determine the effects of the full range of projected maximum/minimum air temperatures and high/low precipitation amounts for hydrological analysis. Evaporation and precipitation are the two most important factors controlling Great Lakes water levels.

CROLEY, T.E. II, and C. He. Spatially distributed watershed model of water and materials runoff. In Wetland and Water Resource Modeling and Assessment: A Watershed Perspective. W. Ji (Ed.). Part II, Wetland Hydrology and Water Budget, Chapter 9. CRC Press, Taylor and Francis Group, Boca Raton, FL, 99-112 (2008).

Agricultural nonpoint source contamination of water resources by pesticides, fertilizers, animal wastes, and soil erosion is a major problem in much of the Laurentian Great Lakes Basin, located between the United States and Canada. Point source contaminations, such as combined sewerage overflows (CSOs), also add wastes to water flows. Soil erosion and sedimentation reduce soil fertility and agricultural productivity, decrease the service life of reservoirs and lakes, and increase flooding and costs for dredging harbors and treating wastewater. Improper management of fertilizers, pesticides, and animal and human wastes can cause increased levels of nitrogen, phosphorus, and toxic substances in both surface water and groundwater. Sediment, waste, pesticide, and nutrient loadings to surface and subsurface waters can result in oxygen depletion and eutrophication in receiving lakes, as well as secondary impacts such as harmful algal blooms and beach closings due to viral and bacterial and/or toxin delivery to affected sites. The U.S. Environmental Protection Agency (EPA) has identified contaminated sediments, urban runoff and storm sewers, and agriculture as the primary sources of pollutants causing impairment of Great Lakes shoreline waters (USEPA 2002). Prediction of various ecological system variables or consequences (such as beach closings), as well as effective management of pollution at the watershed scale, require estimation of both point and nonpoint source material transport through a watershed by hydrological processes. However, currently there are no integrated fine-resolution spatially distributed, physically based watershed scale hydrological/water quality models available to evaluate movement of materials (sediments, animal and human wastes, agricultural chemicals, nutrients, etc.) in both surface and subsurface waters in the Great Lakes watersheds.

CROLEY, T.E. II, and C.F.M. Lewis. Warmer and drier climates that make Lake Huron into a terminal lake. Aquatic Ecosystem Health and Management 11(2):153-160 (2008).

Paleo-hydrologists have adjusted for glacial isostatic uplift and compared the original elevations of paleo-water level indicators and basin outlets for Lake Huron, revealing that Huron lake levels fell tens of meters below its lowest possible outlet (becoming a terminal lake) about 7,900 14C years BP. This corresponds to when the upper Great Lakes stopped receiving glacial melt inflow and became dependent for water supply on precipitation alone, as at present. Since these researchers accounted for differential isostatic effects, they surmised that the upper Great Lakes were impacted by severe dry climate. To understand possible climate changes that led to the closure, the Great Lakes Environmental Research Laboratory applied their Advanced Hydrologic Prediction System to explore deviations from present climates that could force the upper Great Lakes to become terminal. GLERL modeled the steady-state water balance of the present upper Great Lakes with pre-development natural water flow conditions by employing lake outflow-depth rating curves (using estimated sill elevations) reasonable for a natural system and by using dynamic lake areas controlled by observed hypsometric relations for each lake. By using systematic shifts in precipitation and temperature relative to the present base climate, GLERL showed the temperature rises and precipitation drops required for a terminal lake; they may be less extreme if additional effects of past differences in wind speed and insolation are also considered.

CROLEY, T.E. II, D.F. Raikow, C. He, and J.F. Atkinson. Hydrological resource sheds. Journal of Hydrologic Engineering 13(9):873-885 (2008).

When we consider a location with a material  e.g., water, pollutant, sediment  passing through it, we can ask: “Where did the material come from and how long did it take to reach the location?” We can quantify the answer by defining the areas contributing to this location during various time periods as “resource sheds.” Various resource sheds and their source material distributions are rigorously defined and properties derived. For watershed hydrology, we compute resource sheds and their source distributions with a spatially distributed hydrology model by tracing water departing from a “cell”  say 1 km2  over one time interval, traveling through intermediate cells soil, groundwater, and surface zones, and arriving at the watershed mouth in another time interval. This requires modeling all cells, but only tracing contributions from one at a time. By then combining these simulations for all cell loadings, we construct a map of the contributions over the entire watershed for specific departure and arrival time intervals. We then combine results of several sets of simulations to determine the source distribution for any time period and infer resource sheds from these mappings. We give examples for the Maumee River watershed in northern Ohio, discuss computation reduction, and suggest future extensions to other materials. DOI: 10.1061/ ASCE 1084-0699 2008 13:9 873

DYBLE, J., G. L. FAHNENSTIEL, R. W. Litaker, D. F. Millie, and P. A. Tester. Microcystin concentrations and genetic diversity of Microcystis in the lower Great Lakes. Environmental Toxicology 23:507-516 (2008).

The resurgence of Microcystis blooms in the lower Great Lakes region is of great concern to public and ecosystem health due to the potential for these colonial cyanobacteria to produce hepatoxic microcystins. A survey of Microcystis cell densities and microcystin concentrations during August 2004 showed particularly high concentrations of both cells and toxin in the nearshore regions of Saginaw Bay (Lake Huron) and western Lake Erie, often exceeding the World Health Organization’s recommended drinking water limit of 1 μg L-1. The dominant congener of microcystin in both basins was microcystin-LR (MC-LR), whereas the second most abundant congeners, accounting for up to 20–25% of the total microcystin concentrations, were MC-LA in Saginaw Bay and MC-RR in western Lake Erie. Multiplex PCR assays of Microcystis colonies isolated from these two regions showed that a much greater percentage of the Microcystis colonies from Saginaw Bay carried the mcyB gene necessary for microcystin production, in comparison with those from western Lake Erie. The mcyB genotypes sequenced separated into two distinct phylogenetic clusters, with Microcystis originating from Lake Erie predominantly in one branch and from Saginaw Bay present in both branches. These results indicate that the genetic composition of the bloom could impact the concentrations and congeners of microcystin produced and that the cell count methods currently being used to gauge public health threats posed by Microcystis blooms may not sufficiently assess actual bloom toxicity.

FAHNENSTIEL, G.L., D.F. Millie, J. DYBLE, R.W. Litaker, P.A. Tester, M.J. McCORMICK, R. Rediske, and D. Klarer. Microcystin concentrations and cell quotas in Saginaw Bay, Lake Huron. Aquatic Ecosystem Health and Management 11(2):190-195 (2008).

Distribution of the toxin microcystin was studied in Saginaw Bay, Lake Huron during two summer (August) cruises in 2003–2004.  Intracellular microcystin concentrations averaged 1.1 μg l−1 (range 0.01–3.5 μg l−1), and extracellular concentrations averaged only 0.09 μg l−1 (range 0.01–0.18 μg l−1). Highest microcystin concentrations were found in the nearshore regions of the bay, which were shallow and had high total phosphorus concentrations. Microcystin concentrations were strongly correlated with Microcystis aeruginosa abundance (r = 0.8). M. aeruginosa abundance was strongly correlated with total phosphorus, and growth rates were negatively correlated with C:P ratio. Particulate nutrient ratios suggested that Saginaw Bay algae were severely phosphorus deficient. Microcystin cell quotas for M. aeruginosa averaged 140 fg cell−1, and were not correlated with any environmental factor or growth rates. In Saginaw Bay, phosphorus availability primarily influences microcystin concentrations through direct control of M. aeruginosa abundance and growth rates, and not through direct control of cellular microcystin synthesis.

Ge, J., J. Qi, and B.M. LOFGREN. Use of vegetation properties from EOS observations for land-climate modeling in East Africa. Journal of Geophysical Research 113(D15101,  doi:10.1029/2007JD009628):15 pp. (2008).

Land use/cover change has been recognized as a key component in global climate change. Information on land surface biophysical properties and climatic variables based on in situ data fail to resolve the fine-scale variability that exists in many parts of the world, including East Africa. In this study, we used the NASA’s Earth Observing System (EOS) products to improve the representation of the land surface in a regional climate model as well as assess the model performance. The Moderate Resolution Imaging Spectroradiometer (MODIS) data of leaf area index (LAI) and vegetation fractional cover (VFC) were directly incorporated in the Regional Atmospheric Modeling System (RAMS). The model was validated in terms of the land surface temperature (LST), utilizing the MODIS LST data from both Terra and Aqua satellites. Compared with the built-in land surface, the ingested MODIS LAI and VFC greatly improved the spatial and temporal dynamics of vegetation in East Africa. Three experiments were carried out for the year of 2003 to test the impacts of land surface conditions. The results showed that the spatial, seasonal, and diurnal characteristics of the RAMS simulated LST were improved because of MODIS LAI and VFC. Specifically, the Intertropical Convergence Zone (ITCZ)–related migration, bimodal temporal variation, and monthly averaged diurnal cycles of LST were more realistically reproduced. The need to realistically represent the spatial and temporal distribution of vegetation is thus highlighted, and the value of the EOS observations for the land-climate modeling is demonstrated.

Ge, Z., and P.C. LIU. Long-term wave growth and its linear and nonlinear interactions with wind fluctuations. Annales Geophysicae 26:747-758 (2008).

Following Ge and Liu (2007), the simultaneously recorded time series of wave elevation and wind velocity are examined for long-term (on Lavrenov’s  4-scale or 3 to 6 h) linear and nonlinear interactions between the wind fluctuations and the wave field. Over such long times the detected interaction patterns should reveal general characteristics for the wave growth process. The time series are divided into three episodes, each approximately 1.33 h long, to represent three sequential stages of wave growth. The classic Fourier domain spectral and bispectral analyses are used to identify the linear and quadratic interactions between the waves and the wind fluctuations as well as between different components of the wave field. The results show clearly that as the wave field grows the linear interaction becomes enhanced and covers wider range of frequencies. Two different wave-induced components of the wind fluctuations are identified. These components, one at around 0.4 Hz and the other at around 0.15 to 0.2 Hz, are generated and supported by both linear and quadratic windwave interactions probably through the distortions of the waves to the wind field. The fact that the higher-frequency wave-induced component always stays with the equilibrium range of the wave spectrum around 0.4 Hz and the lower frequency one tends to move with the downshifting of the primary peak of the wave spectrum defines the partition of the primary peak and the equilibrium range of the wave spectrum, a characteristic that could not be revealed by short-time wavelet-based analyses in Ge and Liu (2007). Furthermore, these two wave-induced peaks of the wind spectrum appear to have different patterns of feedback to the wave field. The quadratic wave-wave interactions also are assessed using the auto-bispectrum and are found to be especially active during the first and the third episodes. Such directly detected wind-wave interactions, both linear and nonlinear, may complement the existing theoretical and numerical models, and can be used for future model development and validation.

Gray, D.K., T.H. JOHENGEN, D.F. REID, and H.J. MacIsaac. Efficacy of open-ocean ballast water exchange as a means of preventing invertebrate invasions between freshwater ports. Limnology and Oceanography 52(6):2386-2397 (2007).

Ballast water is a major vector of nonindigenous species invasion globally. Mandatory ballast water exchange (BWE) was implemented for vessels carrying ballast water into the Great Lakes in 1993. Despite the implementation of this policy, few data are available on its effectiveness, and invasions have continued to be reported in the Great Lakes. In this study, we conducted experiments to assess the efficacy of BWE on six operational transoceanic vessels traveling from the Great Lakes to European ports. Each vessel had aired ballast tanks, one of which was designated as a control that remained filled with Great Lakes water, while the other was exchanged with mid-ocean water. Community composition was assessed immediately after tanks were filled and again prior to water discharge in European ports. BWE was verified by ship records and, in two cases, by in situ water quality sensors. BWE was highly effective (.99% loss) for reducing concentrations of freshwater zooplankton. Live sentinel amphipods and oligochaetes deployed in incubator chambers sustained nearly universal mortality in tanks that experienced BWE, but not in unexchanged tanks. Finally, BWE reduced in situ recruitment of zooplankton from diapausing eggs present in ballast sediments in additional incubator chambers deployed in these tanks. Collectively, these studies support the contention that BWE by transoceanic vessels traveling between freshwater ports results in ballast water that would exceed proposed International Maritime Organization (2004) ballast water performance standards if these standards were applied to freshwater species only. Thus, BWE provides strong protection to freshwater ecosystems against invasions by both pelagic and benthic freshwater species.

HAND, C.P., S.A. LUDSIN, B.J. Fryer, and J.E. Marsden. Statolith microchemistry as a technique for discriminating among Great Lakes sea lamprey (Petromyzon marinus) spawning tributaries. Canadian Journal of Fisheries and Aquatic Sciences 65:1153-1164 (2008).

Laurentian Great Lakes fishery management agencies are seeking ways to identify natal origins of pamsitic- and spawning-phase sea lamprey (Petromyzon marinus) so that efforts to control this invasive species can be prioritized. We developed laser-ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a technique to quantify elemental concentrations in larval sea lamprey statoliths and explored the use of statolith microchemistry as a tool to discriminate among larval sea lamprey production streams. Our analyses demonstrate that (i) traversing across the statolith with the laser is preferable to drilling down through its apex, (ii) preserving specimens in 95% ethanol versus freezing them has minimal effects on elemental concentrations, (iii) a minimum of 15 individuals per stream should accurately depict stream-specific statolith elemental signatures, and (iv) LA-ICP-MS is preferable to particle-induced X-my emission (PIXE) for statolith analysis, based on higher precision, lower cost, reduced sampling-time requirements, and wider availability. Using LA-ICP-MS, we could discriminate among larvae from 13 streams located in Lakes Michigan, Huron, and Superior with 82% classification accuracy, indicating that this tool holds promise for determining natal origins of sea lamprey in the Great Lakes.

HAWLEY, N., and B.J. EADIE. Observations of sediment transport in Lake Erie during the winter of 2004-2005. Journal of Great Lakes Research 33:816-827 (2007).

Time series measurements of current velocity, wave action, and water transparency were made at two sites—one in 24 m of water and the other in 53 m—in Lake Erie during the fall and winter of 2004–2005. The observations at the shallow site show that bottom resuspension occurred several times during the deployment. Although local resuspension did not occur at the deeper station, several advection episodes were observed. The storms during the observation period were not unusually large, so the processes observed are probably typical of those that occur on a yearly basis. The observations agree reasonably well with previous estimates for both the bottom shear stress during storms, and for the critical shear stress needed to resuspend bottom sediment, but previous estimates of the particle settling velocity are probably too low, while previous estimates of the sediment entrainment rate are too high. The results show that bottom material in the central basin is reworked numerous times before it is finally buried. Deposition in the eastern basin is a more continuous process, but the events observed were not sufficient to match the long-term accumulation rate, so deposition at this site is probably also due in part to larger, more infrequent storms.

He, C., and T.E. CROLEY II. Estimating nonpoint source pollution loadings in the Great Lakes watershed. In Wetland and Water Resource Modeling and Assessment: A Watershed Perspective. W. Ji (Ed.). Part III, Water Quality and Biogeochemical Processes, Chapter 10. CRC Press, Taylor and Francis Group, Boca Raton, FL, pp. 115-127 (2008).

Nonpoint source pollution is the leading source of impairment of U.S. waters (U.S. Environmental Protection Agency [EPA] 2002). In the Great Lakes basin, contaminated sediments, urban runoff and combined sewerage overflows (CSOs), and agriculture have been identified as the primary sources of impairments of the Great Lakes shoreline waters (U.S. EPA 2002). The problems caused by these pollutants include toxic and pathogen contamination of fisheries and wildlife, fish consumption advisories, drinking water closures, and recreational restrictions (U.S. EPA 2002). Management of these problems and rehabilitation of the impaired waters to fishable and swimmable states require identifying impaired waters that are unable to support fisheries and recreational activities and tracking sources of both point and nonpoint source material transport through a watershed by hydrological processes. Such sources include sediments, animal and human wastes, agricultural chemicals, nutrients, and industrial discharges, and so forth.

He, C., T.E. CROLEY II, and Q. Feng. Modeling water movement between the glacial, agricultural oasis and desert in the Heihe Watershed, Northwest China. Proceedings, Fifth International Conference on Geographic Information Systems, Istanbul, Turkey, July 2-5, 2008. 147-153 pp. (2008).

Irrigated farming accounts for more than 80 percent of the total water uses in arid Northwest China. Over the past few decades, rapid population growth, agricultural irrigation expansion, and industrial development have led to groundwater depletion, river flow reduction, and farmland salinization, and ecosystem deterioration in the region. In the context of climate change, how much water will be available to support domestic, irrigation, and industrial supplies while satisfying the needs for maintenance of ecosystems in Northwest China? This paper describes the preliminary work of adapting the U.S. Department of Commerce’s National Oceanic and Atmospheric Administration’s Distributed Large Basin Runoff Model to the Heihe Watershed (the second largest inland river in arid Northwestern China, with a drainage area of 128,000 km2) for understanding glacial/snow melt, groundwater, surface runoff, and evapotranspiration, and for assessing hydrological impacts of climate change and glacial recession on water supply in the middle and lower reaches of the Watershed. Keywords: Glacial Recession, Distributed Large Basin Runoff Model, (DLBRM), Heihe Watershed in Northwestern China, and Water Shortage.

He, C., C. DeMARCHI, and T.E. CROLEY II. Modeling spatial distributions of nonpoint source pollution loadings in the Great Lakes watersheds by using the distributed large basin runoff model. Proceedings, AWRA 2008 Spring Specialty Conference, San Matteo, CA, March 17-19, 2008. 7 pp. (2008).

The NOAA Great Lakes Environmental Research Laboratory, Western Michigan University, and the University of Michigan are jointly developing a physically based, spatially-distributed hydrology model to simulate spatial and temporal nonpoint source material distributions in the Saginaw Bay watersheds, which drains into Lake Huron. Multiple databases of meteorology, land use, topography, hydrography, soils, and agricultural statistics were used to estimate nonpoint source loading potential in the study watersheds. Animal manure production was computed from tabulations of animals by zip code area for the census years of 1987, 1992, 1997, and 2002. Relative chemical loadings for agricultural land use were calculated from fertilizer and pesticide applications for the same periods. These estimates are to be used as the input to the distributed water quality model for simulating pollutant transport through surface and subsurface processes to Great Lakes waters. These simulations, once verified with the in situ Saginaw Bay water quality data, will provide important information to researchers and decision makers for developing the Total Maximum Daily Load programs to minimize the nonpoint source pollution in the watersheds.

HÖÖK, T.O., E. Gorokhova, and S. Hansson. RNA:DNA ratios of Baltic Sea herring larvae and copepods in embayment and open sea habitats. Estuarine, Coastal, and Shelf Science 76:29-35 (2008).

Elucidation of important nursery habitats for young fish can aid in the management and assessment of fish stocks. Herring (Clupea harengus) in the Baltic Sea primarily spawn in coastal areas, but larvae are also present in off-shore, open sea areas. To investigate if sheltered coastal habitats provide a better growth environment for larval herring, we compared short-term growth (as indexed by whole body RNA:DNA ratios) of larval herring from three habitat types of the northwest Baltic proper (sheltered inner bay, exposed outer bay, and open sea). In addition, we compared individual RNA content of adult female Eurytemora affinis (a common Baltic copepod) among these different habitats. High RNA levels in these copepods indicate high production of nauplii, which are important food for larval herring. Both RNA:DNA ratios of larval herring and RNA content of E. affinis were significantly greater in embayment habitats, suggesting that the sheltered coastal areas are high quality nursery habitats for young Baltic herring.

HÖÖK, T.O., E.S. Rutherford, T.E. CROLEY II, D.M. MASON, and C.P. Madenjian. Annual variation in habitat-specific recruitment success: Implications from an individual-based model of Lake Michigan alewife (Alosa pseudoharengus). Canadian Journal of Fisheries and Aquatic Sciences 65:1402-1412 (2008).

The identification of important spawning and nursery habitats for fish stocks can aid fisheries management, but is complicated by various factors, including annual variation in recruitment success. The alewife (Alosa pseudoharengus) is an ecologically important species in Lake Michigan that utilizes a variety of habitats for spawning and early life growth. While productive, warm tributary mouths (connected to Lake Michigan) may contribute disproportionately more recruits (relative to their habitat volume) to the adult alewife population than cooler, less productive nearshore habitats, the extent of interannual variation in the relative contributions of recruits from these two habitat types remains unknown. We used an individual-based bioenergetics simulation model and input data on daily temperatures to estimate alewife recruitment to the adult population by these different habitat types. Simulations suggest that nearshore lake habitats typically produce the vast majority of young alewife recruits. However, tributary habitats may contribute the majority of alewife recruits during years of low recruitment. We suggest that high interannual variation in the relative importance of habitats for recruitment is a common phenomenon, which should be considered when developing habitat management plans for fish populations.

Jin, M., J. WANG, K. Mizobata, H. HU, and K. Shimada. Observations and modeling of the ice-ocean conditions in the coastal Chukchi and Beaufort Seas. Acta Oceanologica Sinica 27(3):79-87 (2008).

The Chukchi and Beaufort Seas include several important hydrological features: inflow of the Pacific water, Alaska coast current (ACC), the seasonal to perennial sea ice cover, and landfast ice along the Alaskan coast. The dynamics of this coupled ice-ocean system is important for both regional scale oceanography and large-scale global climate change research. A number of moorings were deployed in the area by JAMSTEC since 1992, and the data revealed highly variably characteristics of the hydrological environment. Regional high-resolution coupled ice-ocean model of the Chukchi and Beaufort Seas was established to simulate the ice-ocean environment and unique seasonal landfast ice in the coastal Beaufort Sea. The model results reproduced the Beaufort gyre and the ACC. The depth-averaged annual mean ocean currents along the Beaufort Sea coast and shelf break compared well with data from four moored ADCPs, but the simulated velocity had smaller standard deviations, which indicate small-scale eddies were frequent in the region. The model results capture the seasonal variations of sea ice area compared with remote sensing data, and the simulated sea ice velocity showed an almost stationary area along the Beaufort Sea coast that was similar to the observed landfast ice extent. It is the combined effects of the weak oceanic current near the coast, a prevailing wind with an onshore component, the opposite direction of the ocean current, and the blocking by the coastline that make the Beaufort Sea coastal areas prone to the formation of landfast ice.

JOHENGEN, T.H., B.A. Biddanda, and J.B. Cotner. Stimulation of Lake Michigan plankton metabolism by sediment resuspension and river runoff. Journal of Great  Lakes Research 34:213-227 (2008).

Previous work during a major sediment resuspension event (March 1988) in southern Lake Michigan demonstrated that nutrients and carbon derived from resuspended sediment stimulated intense winter heterotrophic production while simultaneously decreasing light availability and autotrophic biomass. However, the role of riverine inputs on plankton metabolism remained unclear. Here we present results from a simulated enrichment experiment (March 2000) designed to examine the influence of resuspended sediments and riverine inputs on Lake Michigan plankton dynamics. Lake water amended with realistic levels of river water, coastal resuspended sediment and river water + sediment all showed enhanced heterotrophic bacterial production and plankton respiration rates, relative to the lake water control. Bacterial production increased by approximately 4× in river water treatments and by a factor of 2.5× for the sediment only treatment compared to lake water controls. Rates of net primary production were stimulated by river water (8.5×) and resuspended sediment (3×), but most by a combination of river water + sediments (11×). Community respiration showed a similar response with rates approximately 8x higher in river water amendment treatments and 3.5× higher in the sediment treatment. Extrapolating experimentally determined production rates to the southern Lake Michigan basin indicated that heterotrophic and autotrophic production in this nearshore region may be enhanced by as much as 3× and 5.2× due to these source inputs. Indeed, field measurements throughout southern Lake Michigan from 1998–2000 support these experimental results. Experimental and field observations suggest that both seasonal riverine inputs and episodic resuspended sediments influence the regional scale ecosystem metabolism and biogeochemistry in Lake Michigan.

Kelley, J.G.W., A.-J. Zhang, P. Chu, and G.A. LANG. Skill assessment of NOS Lake Ontario Operational Forecast System (LOOFS). NOAA Technical Memorandum NOS CS 13. NOAA Office of Coast Survey, Coast Survey Development Lab, Silver Spring, MD, 40 pp. (2008).

This document describes the Lake Ontario Operational Forecast System (LOOFS) and an assessment of its skill. The lake forecast system, based on a hydrodynamic model, uses near real-time atmospheric observations and numerical weather prediction forecast guidance to produce three-dimensional forecast guidance of water temperature and currents and two-dimensional forecasts of water levels for Lake Ontario. LOOFS is the result of technology transfer of the Great Lake Forecasting System (GLFS) and Great Lakes Coastal Forecasting System (GLCFS) from The Ohio State University (OSU) and NOAA’s Great Lakes Environmental Research Laboratory (GLERL) to NOAA’s National Ocean Service (NOS).

Kerfoot, W.C., J.W. Budd, S.A. Green, J.B. Cotner, B.A. Biddanda, D.J. SCHWAB, and H.A. VANDERPLOEG. Doughnut in the desert: Late-winter production pulse in southern Lake Michigan. Limnology and Oceanography 53(2):589-604 (2008).

Contrary to expectations of fairly uniform and unstratified waters, sea-viewing wide field-of-view sensor (SeaWiFS) and moderate-resolution imaging spectroradiometer (MODIS) imagery revealed a spatially complex chlorophyll a pattern, termed the ‘‘doughnut,’’ in southern Lake Michigan during March to April. Phosphorus rich coastal waters and sediments are entrained along gyre convergence zones and moved into deeper waters, stimulating a ring of production. Cross-lake surveys (April 2001 and April 2006) with two separate profiling instruments (vertical Seabird CTD casts, horizontal Acrobat tows) uncovered columnar patterns for Chl a, temperature, and other variables (colored dissolved organic matter, transmissivity) consistent with a spatially complex, rotating gyre structure. Optical plankton counter transects, plankton net tows, and sonar documented that the spatial heterogeneity extends to higher levels of food webs (zooplankton). The horizontal and vertical patterns suggest a previously unrecognized coupling between late-winter storm-induced gyre formation, coastal water plus sediment capture, and deep-water productivity. The pulse may explain how certain zooplankton species characteristic of the Great Lakes can successfully overwinter through what was previously perceived as a very unproductive and resource-stressful period. The magnitude of the winter pulse may be linked to climate change, as higher temperatures and more frequent winter storms suppress coastal ice formation and encourage movement of nutrient-enriched waters and sediments into deeper waters.

Kunkel, K., P. Bromirski, H. Brooks, T. Cavazos, A. Doug, D. Easterling, K. Emanual, P. Groisman, G. Holland, T. Knutson, J. Kosin, P. Komar, D. Levinson, R. Smith, J. Allen, R.A. ASSEL, S. Changnon, J. Lawrimore, K. B. Liu, and T. Peterson. Chapter 2: Observed changes in weather and climate extremes. In Weather and Climate Extremes in a Changing Climate: Regions of Focus: North America, Hawaii, Caribbean, and U.S. Pacific Islands. T.R. Karl, G.A. Meehi, C.D. Miller, S.J. Hassol, A.M. Waple, and W.L. Murray (Eds.). The U.S. Climate Change Science Program and the Subcommittee on Global Change Research, Washington, DC, pp. 35-80 (2008).

Long-term upward trends in the frequency of unusually warm nights, extreme precipitation episodes, and the length of the frost-free season, along with pronounced recent increases in the frequency of North Atlantic tropical cyclones (hurricanes), the length of the frost-free season, and extreme wave heights along the West Coast are notable changes in the North American climate record.

LANDRUM, P.F., S.D. ROBINSON, D.C. GOSSIAUX, J. You, M. J. Lydy, S. Mitra, and T.E.M. tenHulscher. Predicting bioavailability of sediment-associated organic contaminants for Diporeia spp. and oligochaetes. Environmental Science and Technology 41:6442-6447 (2007).

Biota-sediment accumulation factors (BSAF) were calculated for Diporeia spp. and oligochaete worms exposed to polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) from field-collected sediment. These data were compared to the contaminant fraction extracted from sediment with Tenax resin using a 24 h extraction. A previous laboratory study suggested a linear relationship between log BSAF and the contaminant fraction rapidly desorbed from sediment. However, the BSAF data in our study did not fit this relationship. Better predictive regressions for both PCBs and PAHs were found when the log of the lipid-normalized organism contaminant concentrations were plotted against the log of the Tenax-extracted organic carbon-normalized sediment contaminant concentration. Regression lines for the two species had the same slope, but the Diporeia intercept was 2.3 times larger. When adjusted for a 6 h Tenax extraction, based on a regression between 6 and 24 h Tenax extractions, data from this study and two other studies that included multiple oligochaete species fit a single predictive regression. The exception included some PAHs that fell below the regression line. Thus, a single relationship generally predicted bioaccumulation across sediments, compound classes, oligochaete species, and among laboratories.

LESHKEVICH, G. A., and S. V. Nghiem. Satellite SAR remote sensing of Great Lakes ice cover. Part 2: Ice classification and mapping. Journal of Great Lakes Research 33:736-750 (2007).

During the 1997 winter season, shipborne polarimetric backscatter measurements of Great Lakes (freshwater) ice types using the Jet Propulsion Laboratory C-band scatterometer, together with surface-based ice physical characterization measurements and environmental parameters, were acquired concurrently with Earth Resource Satellite 2 (ERS-2) and RADARSAT Synthetic Aperture Radar (SAR) data. This polarimetric data set, composed of over 20 variations of different ice types measured at incident angles from 0° to 60° for all polarizations, was processed to radar cross-section to establish a library of signatures (look-up table) for different ice types. The library is used in the computer classification of calibrated satellite SAR data. Computer analysis of ERS-2 and RADARSAT ScanSAR images of Great Lakes ice cover using a supervised classification technique indicates that different ice types in the ice cover can be identified and mapped, and that wind speed and direction can have an influence on the classification of water as ice based on single frequency, single polarization data. Once satellite SAR data are classified into ice types, the ice map provides important and necessary input for environmental protection and management, ice control and ice breaking operations, and ice forecasting and modeling efforts.

LIEBIG, J. R., and H. A. VANDERPLOEG. Selecting optical plankton counter size bins to optimize zooplankton information in Great Lakes studies. NOAA Technical Memorandum GLERL-143. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 16 pp. (2008).

Equivalent spherical diameter (ESD) size bins for the optical plankton counter (OPC) were determined so as to optimize the OPC for providing abundance of Great Lakes zooplankton species. By determining OPC ESDs for animals of known lengths (L) pumped through laboratory OPC, we derived the ESD/L ratio for a variety of species. Based on the size spectra of individual species lengths determined from net tows and application of previously determined ESD/L ratios, divisions for OPC size bins were selected so as to separate species or groups of species. Since there are differences in zooplankton composition and size within species between Lakes Michigan and Erie, the OPC size bins designated were not the same in the two lakes. This report describes the process used to determine OPC bin sizes and presents the results of an example from Lake Michigan and one from Lake Erie. In addition, ESDs calculated from zooplankton lengths may provide a size metric more useful than length because an ESD more closely resembles visual target strength than length.

LIU, P.C., H.S. Chen, D.-J. Doong, C.C. Kao, and Y.-J.G. Hsu. Monstrous ocean waves during Typhoon Krosa. Annales Geophysicae 26:1327-1329 (2008).

This paper presents a set of ocean wave time series data recorded from a discus buoy deployed near northeast Taiwan in western Pacific that was operating during the passage of Typhoon Krosa on 6 October 2007. The maximum trough-to-crest wave height was measured to be 32.3 m, which could be the largest Hmax ever recorded. Keywords. Meteorology and atmospheric dynamics (Ocean-atmosphere interactions; Waves and tides) – Oceanography: physical (Surface waves and tides) the passage of hurricane Ivan in 2004. Holliday et al. (2006), on the other hand, discovered a recorded Hmax=29.1m from the Shipborne Wave Recorder onboard RRS Discovery on 8 February 2000 in the northeast Atlantic Ocean 250 km west of Scotland during a developing storm. While larger than usual wave heights during a typhoon or hurricane are to be anticipated, there is no tangible knowledge regarding what a typical wave height magnitude is. In this brief report we wish to present the above mentioned wave data as recorded at the Gueishantao Island buoy during Typhoon Krosa that has manifestly exceeded all the previous known extreme wave records.

LIU, P.C., and K.R. MacHutchon. Are there different kinds of rogue waves? Journal of Offshore Mechanics and Arctic Engineering 130:7 pp. (2008).

There is clearly no immediate answer to the question posted by the title of this paper. Inasmuch as that there are not much definitively known about rogue waves and that there is still no universally accepted definition for rogue waves in the ocean, we think there might just be even more than one kind of rogue waves to contend with. While the conventional approach has generally designated waves with Hmax/Hs greater than 2.2 as possible rogue waves, based on Rayleigh distribution considerations, there is conspicuously no provision as to how high the ratio of Hmax/Hs can be and thus not known how high can a rogue wave be. In our analysis of wave measurements made from a gas drilling platform in South Indian Ocean, offshore from Mossel Bay, South Africa, we found a number of cases that indicated Hmax/Hs could be valued in the range between 4 and 10. If this were to be the case, then these records could be considered to be “uncommon” rogue waves, whereas a record of Hmax/Hs in the range between 2 and 4 could be considered to comprise “typical” rogue waves. On the other hand, the spikes in the Hmax data could have been caused by equipment malfunction or some other phenomenon. Clearly, the question of whether or not there are different kinds of rogue waves cannot be readily answered by theoretical considerations alone and there is a crucial need for long-term wave time-series measurements for studying rogue waves. DOI: 10.1115/1.2917431

LIU, P.C., D.J. SCHWAB, C.H. Wu, and K.R. MacHutchon. Wave heights in a 4-D ocean wave field. Proceedings, OMAE 2008 ASME 27th International Conference on Offshore Mechanics and Arctic Engineering, Estoril, Portugal, June 15-20, 2008. 5 pp. (2008).

This paper presents a preliminary examination and analysis of a small suite of 4-D wave data to explore what new insight or inference we can garner -- particularly toward the realm where conventional approaches have not been traversed. While we caught a few glimpses that might indicate a need for new conceptualizations, it by no means to negates the vast positive contributions the conventional approaches have been made in the past century. We feel it is timely to encourage further 4-D ocean wave measurement and thereby facilitate fresh new states of study and understanding of ocean waves.

LOFGREN, B.M., and P. Bieniek. Large-scale 700 hPa height patterns associated with cyclone passage and strong winds on Lake Erie. Journal of Great Lakes Research 34:36-53 (2008).

The difference in 700 hPa height patterns was examined on a seasonal basis between years with high numbers and low numbers of cyclone passages through Lake Erie, and high and low numbers of strong wind events at Cleveland Hopkins Airport. These show that both cyclones and strong wind events often are associated with atmospheric patterns resembling the negative phase of the North Atlantic Oscillation, or the negative phase of the Arctic Oscillation. Custom teleconnection indices were derived from these maps of 700 hPa height differences, and the seasonal means of each of these indices were linearly regressed against the number of cyclones and the number of strong wind events in that season for each year. This procedure led to moderate, but statistically significant, correlation coefficients. This gives some basis for probabilistic prediction of cyclone passages and strong wind events at Lake Erie. Actual application in prediction will require skill also in predicting the geopotential heights, and predictions generalized over larger areas may have greater significance and robustness.

Lohrenz, S.E., G.L. FAHNENSTIEL, and D.F. Millie. Coastal sediment dynamics and river discharge as key factors influencing coastal ecosystem productivity in southeastern Lake Michigan. Oceanography 21(4):60-69 (2008).

A central question addressed by the Episodic Events in the Great Lakes Experiment (EEGLE) was the extent to which the spring phytoplankton bloom in southern Lake Michigan is influenced by a recurrent coastal turbidity plume that results from wind-driven sediment resuspension and transport. Findings from a series of studies conducted as part of EEGLE during spring in 1998, 1999, and 2000 confirmed the importance of sediment processes as a factor influencing ecosystem productivity in southeastern Lake Michigan, but also identified interannual variability in river discharge as potentially important in regulating productivity in coastal waters. Here, we describe the application of satellite-derived and in situ optical observations to examine the impacts of the recurrent coastal turbidity plume (RCP) on light availability and phytoplankton productivity. A review and synthesis of prior work highlighted findings that sediment resuspension during the 1998 El Niño period, a time of intense winter storm activity and an unusually strong RCP, profoundly influenced optical properties in coastal waters, constraining phytoplankton growth and primary production. In contrast, in 1999, a moderate RCP coupled with relatively high discharge from the St. Joseph River led to a strong inner shelf optical signature indicative of elevated levels of dissolved organic matter and apparent enhancement of productivity. We speculate that future changes in climate are likely to alter sediment dynamics and river discharge with uncertain consequences for coastal ecosystem productivity and community structure in southeastern Lake Michigan as well as in other coastal systems.

Madenjian, C.P., D.V. O'Connor, R.R. Rediske, J.P. O'Keefe, and S.A. POTHOVEN. Net trophic transfer efficiencies of polychlorinated biphenyl congeners to Lake Whitefish (Coregonus clupeaformis) from their food. Environmental Toxicology and Chemistry 27(3):631-636 (2008).

Lake whitefish (Coregonus clupeaformis) were fed rainbow smelt (Osmerus mordax) in four laboratory tanks over a 133-d experiment. At the start of the experiment, 10 to 14 of the fish in each tank were sacrificed, and the concentrations of 40 polychlorinated biphenyl (PCB) congeners within these fish were determined. Polychlorinated biphenyl congener concentrations were also determined in the 15 lake whitefish remaining in each of the four tanks at the end of the experiment as well as in the rainbow smelt fed to the lake whitefish. Each lake whitefish was weighed at the start and the end of the experiment, and the amount of food eaten by the lake whitefish during the experiment was tracked. Using these measurements, net trophic transfer efficiency (ϒ) from the rainbow smelt to the lake whitefish in each of the four tanks was calculated for each of the 40 PCB congeners. Results showed that ϒ decreased exponentially as log Kow for the congeners increased from 6 to 8. Further, ϒ averaged 0.70 for the tetrachloro congeners but averaged only 0.45 for the higher chlorinated congeners.

Millie, D.F., G.L. FAHNENSTIEL, J. DYBLE, R.J. Pigg, R.R. Rediske, D.M. Klarer, R.W. Litaker, and P.A. Tester. Influence of environmental conditions on late-summer cyanobacterial abundance in Saginaw Bay, Lake Huron. Aquatic Ecosystem Health and Management 11(2):196-205 (2008).

The relationships among environmental conditions and phytoplankton assemblages were characterized during late summer (2003-2005) in Saginaw Bay, Lake Huron. Differences among sampling stations, arising primarily from spatial disparities in water-column optical properties and nutrient availability, were evident. Cyanobacteria and diatoms dominated phytoplankton assemblages, with the greatest total chlorophyll a concentrations occurring at the innermost portions of the Bay. Microcystis abundance was greatest in the Bay’s upper reaches and decreased with increasing distance from the mouth of the Saginaw River. A suite of variables, indicative of annually-distinct meteorological and hydrological conditions and phosphorus-laden inflows, were identified to (collectively) best ‘group’ stations in a manner consistent with that of phylogenetic-group chlorophyll a concentrations and cyanobacterial biovolumes. However, a great deal of variability between abiotic and biotic patterns remained unexplained and several abiotic variables singularly corresponded with Microcystis abundance. Taken together, it appears that multiple environmental conditions (including annual/episodic meteorological patterns, seasonal/intermittent riverine inflows, annual phosphorus loading, etc.) interact with taxon-specific physiological traits to holistically influence late-summer phytoplankton abundance throughout inner Saginaw Bay.

Mizobata, K., S. Saitoh, and J. WANG. Interannual variability of summer biochemical enhancement in relation to mesoscale eddies at the shelf break in the vicinity of the Pribilof Islands, Bering Sea. Deep-Sea Research II 55:1717-1728 (2008).

This study examined variability of the eddy field and primary production over the Bering Sea’s eastern shelf break area during summer using a satellite multi-sensor data set. The eddy field and on-shelf nutrient flux below 50 m water depth were also investigated using a numerical model. The satellite altimeter data analysis and numerical experiments indicated that the eddy field was induced by perturbations of the Bering Slope Current system and/or instabilities in the Bering Sea basin via flow through the Aleutian passes. The distribution of high primary production roughly coincided with the high variability area of the eddy field. Numerical experiments showed a 70% increase in net on-shelf flux and 54% increase in net on-shelf transport by the generation/propagation of eddies along the shelf break. At Pribilof Canyon, towed CTD/fluorometer measurements during the summer of 2003 revealed a stable water column and high fluorescence (>10 μg L -1) in the area between the 200- and 1000-m isobaths at a time when there was a low level of on-shelf flux regardless of the eddy field. Conversely, the eddy-induced, on-shelf flux and stable water column can enhance primary production from spring to summer at the shelf break. Moreover, the eddy-induced on-shelf nutrient flux probably contributes to the primary productivity at the western shelf of the Pribilof Islands where the Bering Sea ecosystem is very dynamic. This eddy-related shelf break process can be applied to not only the Bering Sea shelf break but also all shelf break areas in which propagating eddies are found.

NALEPA, T.F., D.L. FANSLOW, G.A. LANG, D.B. LAMARAND, L.G. CUMMINS, and G.S. CARTER. Abundances of the amphipod Diporeia spp. and the mussels Dreissena polymorpha and Dreissena rostriformis bugensis in Lake Michigan in 1994-1995, 2000, and 2005. NOAA Technical Memorandum GLERL-144. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 25 pp. (2008).

This technical report provides basic results of benthic surveys conducted in Lake Michigan in 1994-1995, 2000, and 2005. The focus of these surveys was to assess lakewide trends in abundances of the amphipod Diporeia spp., the zebra mussel (Dreissena polymorpha), and the quagga mussel (Dreissena rostriformis bugensis).  These lakewide surveys were an expansion of a monitoring program in the southern basin that has examined trends in the abundance and composition of the macroinvertebrate community since 1980 (Nalepa 1987, Nalepa et al. 1998). The original purpose of the monitoring program was to assess the response of the benthic community to phosphorus abatement efforts in the mid-1970s (Nalepa 1987).  However, after D. polymorpha became established in the southwestern portion of the lake in 1989 (Marsden et al. 1993), the monitoring program detected several dramatic changes in the benthic community in the early 1990s. For one, the Diporeia population began to systematically disappear (Nalepa et al. 1998).  Also, D. polymorpha rapidly expanded and soon became dominant in the nearshore region. To determine if the same dramatic changes in the southern basin were occurring over a broader lake area, the monitoring program was expanded in 1994-1995 to include the entire lake.  Sampling in these two years was conducted jointly with several other Lake Michigan programs -- Environmental Monitoring and Assessment (EMAP) and Lake Michigan Mass Balance (LMMB).  After 1994-1995, lakewide monitoring of Diporeia and Dreissena populations continued at 5-year intervals (i.e., in 2000 and 2005) as part of a regular monitoring program. The purpose of this report is to provide all abundance data collected in 1994-1995, 2000, and 2005, and to provide basic details of the lakewide sampling program, including station locations, sampling methods, and laboratory procedures. Data are presented with little attempt at interpretation; detailed analysis and discussions of relevance will be provided in other publications (see Nalepa et al. in press).

Nghiem, S.V., and G.A. LESHKEVICH. Satellite SAR remote sensing of Great Lakes ice cover, Part 1. Ice backscatter signatures at C Band. Journal of Great Lakes Research 33:722-735 (2007).

For remote sensing of Great Lakes ice cover, a field experiment campaign was conducted in the 1997 winter season across the Straits of Mackinac and Lake Superior. The campaign was coordinated in two expeditions on two different United States Coast Guard icebreaker vessels, the Biscayne Bay in February and the Mackinaw in March. Aboard these icebreakers, the Jet Propulsion Laboratory Cband polarimetric scatterometer was used to measure backscatter signatures of various ice types and open water at incidence angles from 0° to 60°. The radar measurements include incidence angles and polarizations of spaceborne Synthetic Aperture Radars (SAR) on ERS, RADARSAT, and Envisat satellites. The radar data together with in situ measurements form a signature library that can be used to interpret SAR data for ice classification and mapping. Results are presented for backscatter signatures of Great Lakes ice types from thin lake ice to thick brash ice with different snow-cover and surface conditions. The signature library indicates that several ice types can be identified with multi-polarization SAR data; however, single-polarization data can result in misclassification of ice and open water at different ranges of incidence angle and wind conditions. For incidence angles larger than 30°, thick brash ice, the most difficult for icebreaking operations and the most hazardous for ship navigation, can be uniquely identified by co-polarized backscatter for all wind conditions below the gale force.

Olson, J.M., G. Alagarswamy, J.A. Andresen, D.J. Campbell, A.Y. Davis, J. Ge, M. Huebner, B.M. LOFGREN, D.P. Lusch, N.J. Moore, B.C. Pijanowski, J. Qi, P.K. Thornton, N.M. Torbick, and J. Wang. Integrating diverse methods to understand climate-land interactions in East Africa. Geoforum 39:898-911 (2008).

The questions of how land use change affects climate, and how climate change affects land use, require examination of societal and environmental systems across space at multiple scales, from the global climate to regional vegetative dynamics to local decision making by farmers and herders. It also requires an analysis of causal linkages and feedback loops between systems. These questions and the conceptual approach of the research design of the Climate–Land Interaction Project (CLIP) are rooted in the classical human–environment research tradition in Geography. This paper discusses a methodological framework to quantify the two-way interactions between land use and regional climate systems, using ongoing work by a team of multi-disciplinary scientists examining climate–land dynamics at multiple scales in East Africa. East Africa is a region that is undergoing rapid land use change, where changes in climate would have serious consequences for people’s livelihoods, and requiring new coping and land use strategies. The research involves exploration of linkages between two important foci of global change research, namely, land use/land cover (LULC) and climate change. These linkages are examined through modeling agricultural systems, land use driving forces and patterns, the physical properties of land cover, and the regional climate. Both qualitative and quantitative methods are being used to illustrate a diverse pluralism in scientific discovery.

POTHOVEN, S.A., S.A. LUDSIN, T.O. HÖÖK, D.L. FANSLOW, D.M. MASON, P.D. Collingsworth, and J.J. VanTassel. Reliability of bioelectrical impedence analysis for estimating whole-fish energy density and percent lipids. Transactions of the American Fisheries Society 137:1519-1529 (2008).

We evaluated bioelectrical impedance analysis (BIA) as a nonlethal means of predicting energy density and percent lipids for three fish species: yellow perch Perca flavescens, walleye Sander vitreus, and lake whitefish Coregonus clupeaformis. Although models that combined BIA measures with fish wet mass provided strong predictions of total energy, total lipids, and total dry mass for whole fish, including BIA provided only slightly better predictions than using fish mass alone. Regression models that used BIA measures to directly predict the energy density or percent lipids of whole fish were generally better than those using body mass alone (based on Akaike’s information criterion). However, the goodness of fit of models that used BIA measures varied widely across species and at best explained only slightly more than one-half the variation observed in fish energy density or percent lipids. Models that combined BIA measures with body mass for prediction had the strongest correlations between predicted and observed energy density or percent lipids for a validation group of fish, but there were significant biases in these predictions. For example, the models underestimated energy density and percent lipids for lipid-rich fish and overestimated energy density and percent lipids for lipid-poor fish. A comparison of observed versus predicted whole-fish energy densities and percent lipids demonstrated that models that incorporated BIA measures had lower maximum percent error than models without BIA measures in them, although the errors for the BIA models were still generally high (energy density: 15–18%; percent lipids: 82–89%). Considerable work is still required before BIA can provide reliable predictions of whole-fish energy density and percent lipids, including understanding how temperature, electrode placement, and the variation in lipid distribution within a fish affect BIA measures.

POTHOVEN, S.A., and C.P. Madenjian. Changes in consumption by alewives and lake whitefish after Dreissenid mussel invasions in Lakes Michigan and Huron. North American Journal of Fisheries Management 28:308-320 (2008).

Growth of alewives Alosa pseudoharengus and lake whitefish Coregonus clupeaformis has declined since the arrival and spread of dreissenid mussels in Lakes Michigan and Huron. Alewives are the main forage for the salmonids in Lake Michigan, and lake whitefish are the most important commercial species in both lakes. Bioenergetics modeling was used to determine consumption by the average individual fish before and after the dreissenid invasion and to provide insight into the invasion’s effects on fish growth and food web dynamics. Alewives feed on both zooplankton and benthic macroinvertebrates, and lake whitefish are benthivores. Annual consumption of zooplankton by an average alewife in Lake Michigan was 37% lower and consumption of benthic macroinvertebrates (amphipods Diporeia spp., opossum shrimp Mysis relicta, and Chironomidae) was 19% lower during the post-invasion period (1995–2005) than during the pre-invasion period (1983–1994). Reduced consumption by alewives corresponded with reduced alewife growth. In Lakes Michigan and Huron, consumption of nonmollusk macroinvertebrates (Diporeia spp., opossum shrimp, Chironomidae) by the average lake whitefish was 46–96% lower and consumption of mollusks (mainly dreissenids and gastropods) was 2–5 times greater during the post-invasion period than during the pre-invasion period. Even though total food consumption by lake whitefish did not differ between the two periods in Lake Huron or the Southern Management Unit in Lake Michigan, post-invasion weight at age was at least 38% lower than pre-invasion weight at age. Under the current post-invasion diet regime, consumption by lake whitefish would have to increase by up to 122% to achieve pre-invasion growth rates.

Redalje, D.G., S.D. Lohrenz, M.J. Natter, M.D. Tuel, G.J. Kirkpatrick, D.F. Millie, G.L. FAHNENSTIEL, and F.M. VanDohal. The growth dynamics of Karenia brevis within discrete blooms on the West Florida Shelf. Continental Shelf Research 28:24-44 (2008).

As part of the ECOHAB: Florida Program, we studied three large blooms of the harmful bloom forming dinoflagellate Karenia brevis. These blooms formed on the West Florida Shelf during Fall of 2000 off Panama City, and during Fall 2001 and Fall 2002 off the coastline between Tampa Bay and Charlotte Harbor. We suggest that these blooms represent two different stages of development, with the 2000 and 2001 blooms in an active growth or maintenance phase and the 2002 bloom in the early bloom initiation phase. Each bloom was highly productive with vertically integrated primary production values of 0.47–0.61, 0.39–1.33 and 0.65 g C m-2 d-1 for the 2000, 2001 and 2002 K. brevis blooms, respectively. Carbon specific growth rates were low during each of these blooms with values remaining fairly uniform with depth corresponding to generation times of 3–5 days. Nitrogen assimilation by K. brevis was highest during 2001 with values ranging from 0.15 to 2.14 μmol NL-1 d-1 and lower generally for 2000 and 2002 (0.01–0.64 and 0.66–0.76 μmol NL-1 d-1 for 2000 and 2002, respectively). The highest K. brevis cell densities occurred during the 2001 bloom and ranged from 400
to 800 cells mL-1. Cell densities were lower for each of the 2000 and 2002 blooms relative to those for 2001 with densities ranging from 100 to 500 cells mL-1. The 2000 and 2001 blooms were dominated by K. brevis in terms of its contribution to the total chlorophyll a (chl a) pool with K. brevis accounting generally for >70% of the observed chl a. For those populations that were dominated by K. brevis (e.g. 2000 and 2001), phytoplankton C biomass (Cp,0) constituted <30% of the total particulate organic carbon (POC). However, in 2002 when diatoms and K. brevis each contributed about the same to the total chl a, Cp,0 was >72% of the POC. The fraction of the total chl a that could be attributed to K. brevis was most highly correlated with POC, chl a and salinity. Nitrogen assimilation rate and primary production were highly correlated with a greater correlation coefficient than all other comparisons.

REID, D.F. Ballast water and saltwater flushing: Closing a gap in the protection framework for the Great Lakes. ANS Update 14(1):2 pp. (2008).

Ballast water was identified as a vector for invasive species to the Great Lakes region in the late 1980s. In 1993 the U.S. established regulations for ships with (pumpable) ballast water to conduct open-ocean ballast water exchange (BWE) in order to conduct ballast operations in the Great Lakes (and upper Hudson River). Ships not carrying pumpable ballast water were not regulated. The recommendation for BWE was based on the idea that ballast water of coastal origin and containing coastal organisms would be replaced by mid-ocean seawater and organisms, the latter being far lower in population density and less likely to survive if discharged into the freshwater Great Lakes. However, the efficacy of BWE has been seriously questioned in recent years because of the continued discovery of new aquatic nonindigenous species (ANS) in the Great Lakes since 1993.

Richardson, C.J., R.S. King, S.S. Qian, P. Vaithiyanathan, R.G. Qualls, and C.A. STOW. Estimating ecological thresholds for phosphorus in the Everglades. Environmental Science and Technology 41(23):8084-8091 (2007).

The Florida Everglades, a wetland of international importance, has been undergoing a significant shift in its native flora and fauna due to excessive total phosphorus (TP) loadings (an average of 147 t per annum from 1995 to 2004) and an elevated mean TP concentration (69 μg L-1 of TP in 2004) from agricultural runoff and Lake Okeechobee outflow despite the use of 16000 ha of stormwater treatment areas. Here, we present a Bayesian change point analysis of long-term experimental research and show that exceeding a surface water geometric mean TP threshold concentration of 15 μg L-1 causes an ecological imbalance in algal, macrophyte, and macroinvertebrate assemblages as well as slough community structure. A phosphorus threshold for all trophic levels may be more realistic and protective when presented as a threshold zone (12–15 μg L-1) because estimates of uncertainty must be utilized to accurately define TP thresholds, which change with seasons and water depths. Most interior areas of the Everglades are currently at or below this threshold zone, but the exterior areas near inflow structures (except for the Everglades National Park) are presently receiving double or triple the proposed threshold. Our Bayesian approach, used here to address ecological imbalance along nutrient gradients, is applicable to determining thresholds and stable states in other aquatic ecosystems.

Richardson, C.J., R.S. King, S.S. Qian, P. Vaithiyanathan, R.G. Qualls, and C.A. STOW. Response to comment on "Estimating ecological thresholds for phosphorus in the Everglades". Environmental Science and Technology 42:6772-6773 (2008).

We thank Gaiser et al. for their comments (1) on our article (2). We support their contention that excess phosphorus has caused serious ecological effects and that caution must be taken when setting water quality standards to provide the best protection for an ecosystem. However, we disagree with their interpretation that our approach fails to protect wetlands because it bases thresholds on averages and with their view that “any” increase above ambient background concentrations causes an ecological imbalance.

Richardson, C.J., R.S. King, S.S. Qian, P. Vaithiyanathan, R.G. Qualls, and C.A. STOW. An ecological basis for establishment of a phosphorus threshold for the Everglades ecosystem. In The Everglades Experiment. Lessons for Ecosystem Restoration. C.J. Richardson (Ed.). Springer, New York, NY, 595-616 (2008).

Numerous studies have shown that the Everglades fen is a phosphorus-limited ecosystem (Steward and Ornes 1975a,b; Craft and Richardson 1993a; Koch and Reddy 1992; Richardson et al. 1999; Richardson and Qian 1999; Noe et al. 2001). From this it can be hypothesized that increases in phosphorus concentrations in the water column and the soils of the Everglades above the ecosystem's P assimilative capacity (Cha. 23) will result in significant imbalances in the structure and function of the Everglades ecosystem (Richardson and Qian 1999).

Richardson, C.J., P. Vaithiyanathan, R.G. Qualls, M.B. Bush, C.A. STOW, and M. Ho. Water quality, soil chemistry, and ecosystem responses to P dosing. In The Everglades Experiments.  Lessons for Ecosystem Restoration. C.J. Richardson (Ed.). Springer, New York, NY, 385-416 (2008).

Our mesocosm study consisted of flumes or channels established in 1991 in two unimpacted slough communities in unenriched areas of WCA-2A (see Figs. 14.1 and 14.2, Chap 14, Plate 7). The word "mesocosm" here refers to an experimental enclosure where only phosphorus concentrations were chemically manipulated.

ROBERTS, J.J., and F.J. Rahel. Irrigation canals as sink habitat for trout and other fishes in a Wyoming drainage. Transactions of the American Fisheries Society 137:951-961 (2008).

Irrigation canals can be a major source of mortality for fish in the Rocky Mountain region. Our study looked at how fish were affected by the irrigation canal system in the Smiths Fork, a tributary to the Bear River in western Wyoming. There are two native species of conservation concern in the Smiths Fork drainage: Bonneville cutthroat trout Oncorhynchus clarkii utah and northern leatherside chub Lepidomeda copei. Our objectives were to determine the relative abundance of each species within the canals and the fate of trout (Bonneville cutthroat trout and brown trout Salmo trutta) that enter canals. During the summer of 2003 we sampled 30 sites within the Covey Canal system, which is the largest canal system withdrawing water from the Smiths Fork. Because fish were observed to accumulate at certain spots in the canal system, we developed a sampling scheme that incorporated both random sample sites and sites known to attract fish. We estimated that between 6,300 and 10,400 fish encompassing 10 species were entrained in this canal system. The two most abundant species were speckled dace Rhinichthys osculus (29% of all fish) and mountain sucker Catostomus platyrhynchus (37% of all fish). Bonneville cutthroat trout and northern leatherside chub each comprised 2% of the total entrained fish. We implanted 30 Bonneville cutthroat trout and 13 brown trout with radio transmitters to determine whether entrained trout could leave the canal system when water levels were reduced in late summer. We found that 77% of the transmitter-implanted fish died within the canals, indicating that this system functions as sink habitat for Bonneville cutthroat trout and brown trout. Based on this mortality rate, we estimated that 120 Bonneville cutthroat trout (95% confidence interval, 75–165) and 299 brown trout (280–317) perished in the Covey Canal system during the summer of 2003.

ROBINSON, S. D., P. F. LANDRUM, P. L. VanHoof, and B. J. EADIE. Seasonal variation of polychlorinated biphenyl congeners in surficial sediment, trapped settling material, and suspended particulate matter in Lake Michigan, USA. Environmental Toxicology and Chemistry 27(2):313-322 (2008).

A unique time series of surface sediment, trapped settling material, and suspended particulate material polychlorinated biphenyl (PCB) samples were collected at a 45-m deep site off Grand Haven (MI, USA) over a 14-month period. Both concentrations and congener distributions remained constant for the sediments, although there were seasonal and interannual variability in the other matrices. Trapped settling material and suspended particulate material PCB concentrations were substantially lower (~50%) in 1997 than in the samples from December 1997 through July 1998. The cause could not be determined from the data collected, but there were some very large storms during the winter–spring period of 1998, resulting in major sediment resuspension throughout the southern basin. Observed seasonal variation in PCB concentration and congener distribution on particles likely was due to the changes in particle composition. These include particle size and the source of particles (such as the amount of resuspended sediment in trapped settling material), and the role of diagenesis of the organic matter on particles.

RUBERG, S.A., R.W. MUZZI, S.B. BRANDT, J.C. LANE, T.C. MILLER, J.J. Gray, S.A. CONSTANT, and E.J. Downing. A wireless internet-based observatory: The Real-time Coastal Observation Network (ReCON). Proceedings, Marine Technology Society/IEEE Oceans 2007 Conference, Vancouver, British Columbia, Canada, September 30-October 5, 2007. 6 pp. (2007).

ReCON, a coastal observation network with nodes on Lakes Michigan, Huron, and Erie, has been designed to allow flexible deployment of coastal access points and simplified integration of sensor packages. The system provides continuous observations of chemical, biological, and physical parameters, facilitates modification of sampling parameters in anticipation of episodic events, facilitates collection of field samples in response to episodic events, supports long term research and contributes to sensor and system development. The system currently supports projects addressing harmful algal bloom (HAB) detection, human health observations related to beach closures and drinking water processing concerns, rip current warnings, integrated ecosystem assessment, and public access to historic shipwrecks at the Thunder Bay National Marine Sanctuary. ReCON system development relies on wireless broadband technology and a network-based underwater hub designed to allow expansion via satellite nodes. The system architecture allows simplified integration of sensors from various institutions through guest ports. Access to and control of instrumentation is made available to the scientific community and educational institutions through the internet. A real-time database management system provides data and information for forecast model initial conditions, forecast verification, public information, and educational outreach. The technology demonstrated on the ReCON project represents an important contribution to the success of regional coastal ocean observing systems. The pervasiveness of wireless internet technology in coastal regions represents an opportunity to significantly expand high bandwidth coastal observation capabilities. Implementing ReCON on a regional coastal level in the Great Lakes has contributed to better tools and understanding for managers and educators, more on-water observations for marine forecasters, and improved scientific measurements.

Santagata, S., Z. R. Gasinaite, E. Verling, J.R. Cordell, K. Eason, J.S. Cohen, K. Bacela, G. Quilez-Badia, T.H. JOHENGEN, D.F. REID, and G.M. Ruiz. Effect of osmotic shock as a management strategy to reduce transfers of non-indigenous species among low-salinity ports by ships. Aquatic Invasions 3(1):61-76 (2008).

Open-ocean ballast-water exchange (BWE) is currently the most common treatment used to reduce the ballast transfer of organisms and the subsequent risk of invasions among coastal ecosystems. Freshwater or estuarine organisms remaining after BWE often experience high mortality, due to osmotic shock caused by high-salinity exposure. We conducted 70 salinity tolerance experiments on 54 different taxa to measure mortality rates of freshwater and estuarine organisms after exposure to oceanic seawater (34 psu), simulating both flow-through (F-T) and empty-refill (E-R) BWE methods. We focused especially on larval and adult crustaceans from freshwater and mesohaline habitats adjacent to ports of the Baltic Sea, North Sea, Great Lakes, Chesapeake Bay, and San Francisco Bay. Animals from oligohaline habitats (0-2 psu) experienced the highest mortality: all individuals died in 82% of the F-T treatments and 88% of the E-R treatments. The effectiveness of both treatment types decreased with animals from low-salinity (2-5 psu, 100% mortality in 27% of F-T and 46% of E-R treatments) and mesohaline habitats (5-18 psu, 100% mortality in 40% of F-T and 52% of E-R treatments). In 43% of cases among all salinity categories, empty-refill treatments required less exposure time to cause significant mortality than flow-through treatments. Invertebrates that exhibited significant survivorship were most often peracarid crustaceans including widely introduced species of mysid shrimps and amphipods. Although salinity shock does not completely prevent the transfer of all low-salinity biota, BWE provides a useful management tool to reduce species transfers, especially considering the combined effects of removal and mortality.

Schertzer, W.M., R.A. ASSEL, D. BELETSKY, T.E. CROLEY II, B.M. LOFGREN, J.H. SAYLOR, and D.J. SCHWAB. Lake Huron climatology, inter-lake exchange and mean circulation. Aquatic Ecosystem Health and Management 11(2):144-152 (2008).

Selected key features of the physical limnology, hydrology and climate influencing Lake Huron is presented. The lake is deep (229 m), consists of four interconnected bodies of water and currently there are no diversions into or out of the lake. Long-term annual summaries of meteorological and hydrological variables show that the lake affects spatial distributions across the basin. An estimate of the long-term hydrologic budget shows the relative importance of the major inflows, outflows and net basin supply. Long-term monthly average water level is 176.6 m. Monthly mean total heat flux ranges from −155 W m−2 in December to 154 W m−2 in June. Light attenuation is higher in Saginaw Bay and the nearshore compared to the mid-lake. Ice extent can be an important factor in the Lake Huron system with values ranging from <10% to >90% depending on winter severity. Surface and mean lake temperature for shallow North Channel are similar, however, large volumes of main Lake Huron and Georgian Bay results in mean temperatures nearly 10oC less than surface temperatures in summer. Inter-lake exchange at the Straits of Mackinac is about 2 cm s−1 but fluctuating flows can be up to 30 times larger. The averaged summer and winter circulation shows cyclonic patterns for Lake Huron.

SELLINGER, C.E., C.A. STOW, E.C. Lamon, and S.S. Qian. Recent water level declines in the Lake Michigan-Huron system. Environmental Science and Technology 42(2):367-373 (2008).

Great Lakes water levels have fluctuated over thousands of years. High water levels were a problem in the 1980s, but a recent sudden drop in Lakes Michigan and Huron has caused particular concern, in part because lower water levels are consistent with many global climate change scenarios. We examined water level data (1860–2006) representing Lakes Michigan and Huron to evaluate changes in both long-term and seasonal patterns over time, and explore relationships with candidate predictor variables. Our tools for this analysis included both Seasonal Trend decomposition using Loess (STL), and dynamic linear models (DLM). In addition to the recent decline, STL results reveal a sustained decline around 1900, a long-term periodicity of ∼30 years, and an unexpected correspondence with sunspot activity. DLM results indicate a relationship with precipitation over a three-year lagged period, which has been essentially unchanging from 1900 to present. Additionally, the DLM highlights an underlying lake level decline beginning in ∼1973 and continuing to the present, which may have been obscured by concurrently increasing precipitation into the 1990s. The current underlying decline might be related to a simultaneous evaporation increase, however, our model could not confirm this relationship, possibly due to the shorter period of record for evaporation data. We cannot be certain that the present observed water level drop is caused by factors related to global climate change, or that it portends a long-term problem. However, because the underlying decline has been ongoing for ∼33 years it may be prudent to include lower lake levels in future management planning.

STOW, C.A., K.H. Reckhow, S.S. Qian, E.C. Lamon, G.B. Arhonditsis, M.E. Borsuk, and D. Seo. Approaches to evaluate water quality model parameter uncertainty for adaptive TMDL implementation. Journal of the American Water Resources Association 43(6):1499-1507 (2007).

The National Research Council recommended Adaptive Total Maximum Daily Load implementation with the recognition that the predictive uncertainty of water quality models can be high. Quantifying predictive uncertainty provides important information for model selection and decision-making. We review five methods that have been used with water quality models to evaluate model parameter and predictive uncertainty. These methods (1) Regionalized Sensitivity Analysis, (2) Generalized Likelihood Uncertainty Estimation, (3) Bayesian Monte Carlo, (4) Importance Sampling, and (5) Markov Chain Monte Carlo (MCMC) are based on similar concepts; their development over time was facilitated by the increasing availability of fast, cheap computers. Using a Streeter-Phelps model as an example we show that, applied consistently, these methods give compatible results. Thus, all of these methods can, in principle, provide useful sets of parameter values that can be used to evaluate model predictive uncertainty, though, in practice, some are quickly limited by the ‘‘curse of dimensionality’’ or may have difficulty evaluating irregularly shaped parameter spaces. Adaptive implementation invites model updating, as new data become available reflecting water-body responses to pollutant load reductions, and a Bayesian approach using MCMC is particularly handy for that task.

VANDERPLOEG, H.A., T.H. JOHENGEN, and J.R. LIEBIG. Feedback between zebra mussel selective feeding and algal composition affects mussel condition: did the regime changer pay a price for its success? Freshwater Biology 54:47-63 (2009).

1. We investigated the role of algal composition on pumping, clearance, assimilation, pseudofaeces and faeces production, feeding time budgets, and condition of zebra mussels from spring to autumn at two sites in Saginaw Bay (Lake Huron) and one site in western Lake Erie. Size-fractioned chlorophyll was used to distinguish between feeding on small (<53 lm) and large (>53 lm) size fractions, and mussel feeding behaviour was quantified by video observations. 2. Mussel pumping, clearance and assimilation rates varied among sites, particularly during summer, when phytoplankton composition varied considerably among sites. Lowest values were seen at the inner-bay site of Saginaw Bay, low to moderate values at the outer-bay site of Saginaw Bay, and high values at the Lake Erie site. Clearance, pumping and assimilation rates were all highly positively correlated (R2 = 0.76) with per cent contribution of flagellates to total algal biomass and negatively correlated with per cent of Microcystis aeruginosa (R2 = 0.63). The negative effects on pumping rate (as determined by clearance rate on the <53 lm fraction) of Microcystis, which occurred in the >53 lm fraction, could be mitigated by the presence of flagellates in the <53 lm fraction. 3. Visual observations of mussel feeding showed evidence for poor seston quality during summer negatively affecting feeding rates. High faeces production during times of low assimilation rate was suggestive of poor assimilation efficiency and ⁄ or viable gut passage of grazing resistant algae. Long periods of time not filtering by the mussels during some Microcystis blooms and lack of production of a filtering current during one experiment were suggestive of intoxication from microcystin or other secondary compounds. 4. Clearance and feeding rates of the mussels in Saginaw Bay were high during spring and autumn and very low in summer, particularly at the inner-bay site. Condition of the mussels (mass : length ratio) was highest in spring and lowest during summer. This seasonal variation probably reflected high food assimilation rate during autumn and spring and low assimilation rate and reproduction during summer. The condition of mussels throughout the year was higher at the outer-bay than the inner-bay site, reflecting better feeding conditions at the former. Mussel selective feeding may have been responsible for the poor quality of food at the inner bay site; therefore, we postulate that a regime shift in phytoplankton composition promoted by the mussels fed back into lowered condition of the mussels.

WANG, H.-Y., T.O. HÖÖK, M.P. Ebener, L.C. Mohr, and P.J. Schneeberger. Spatial and temporal variation of maturation schedules of lake whitefish (Coregonus cleupaformis) in the Great Lakes. Canadian Journal of Fisheries and Aquatic Sciences 65:2157-2169 (2008).

Fish maturation schedules vary greatly among systems and over time, reflecting both plastic and adaptive responses to ecosystem structure, physical habitats, and mortality (natural and fishing). We examined maturation schedules of commercially exploited lake whitefish (Coregonus clupeaformis) in the Laurentian Great Lakes (Lakes Michigan, Huron, and Superior) by estimating ages and lengths at 50% maturity, age-specific maturity ogives (age-specific probability of being mature), and probabilistic maturation reaction norms (PMRNs; a metric that accounts for effects of growth and mortality). Collectively, these estimates indicated variation in maturation schedules between sexes (i.e., males tend to mature at younger ages and shorter lengths than females) and among systems (midpoint estimates of PMRNs were smallest for Lake Michigan fish, intermediate for fish in the main basin of Lake Huron, and largest for fish in Lake Huron’s Georgian Bay and Lake Superior). Temporally, recent increases in age at 50% maturity in Lakes Huron and Michigan may primarily reflect plastic responses to decreased growth rates associated with ecosystem changes (e.g., declines of the native amphipod, Diporeia spp.). As plastic and adaptive changes in maturation schedules of fish stocks may occur simultaneously and require different management considerations, we recommend the concomitant analysis of multiple maturation indices.

Waples, J.T., B.J. EADIE, J. Val Klump, M. Squires, J.B. Cotner, and G. McKinley. Chapter 7: The Laurentian Great Lakes. North American Continental Margins: A Synthesis and Planning Workshop. Report of the North American Continental Margins Group for the U.S. Carbon Cycle Scientific Steering Group and Interagency Working Group. B. Hales, W.-J. Cai, B.G. Mitchell, C.L. Sabine, and O. Schofield (Eds). U.S. Carbon Cycle Science Program, Washington, DC, pp. 73-81 (2008).

North America’s inland ocean, the Great Lakes (Figure 7.1), contains about 23,000 km3 (5,500 cu. mi) of water (enough to flood the continental United States to a depth of nearly 3 m), and covers a total area of 244,000 km2 (94,000 sq. mi) with 16,000 km of coastline. The Great Lakes comprise the largest system of fresh, surface water lakes on earth, containing roughly 18% of the world supply of surface freshwater. Reservoirs of dissolved carbon and rates of carbon cycling in the lakes are comparable to observations in the marine coastal oceans (e.g., Biddanda et al. 2001) (Table 7.1). The drainage area of the Laurentian system (including the Saint Lawrence River) is approximately 1.0 million km2—approximately one-third of the Mississippi River watershed or roughly 4% of the surface area of North America. The Great Lakes drain through the Saint Lawrence River, which flows approximately 1200 km before emptying into the largest estuary in the world, the Gulf of Saint Lawrence. This feature of the Great Lakes system is unique in relation to the other marginal regions: exchange with the open ocean is in only one direction, to the ocean. Because of the large size of the watershed, physical characteristics such as climate, soils, and topography vary across the basin. Terrestrial and atmospheric forcing is strongly latitude-dependent in this large basin. To the north, the climate is cold and the terrain is dominated by a granitic bedrock called the Canadian (or Laurentian) Shield consisting of Precambrian rocks under a generally thin layer of acidic soils. Conifers dominate the northern forests. In the southern areas of the basin, the climate is much warmer. The soils are deeper with layers or mixtures of clays, carbonates, silts, sands, gravels, and boulders deposited as glacial drift or as glacial lake and river sediments. The lands are usually fertile and have been extensively drained for agriculture. The original deciduous forests have given way to agriculture and sprawling urban development. This variability has strong impacts on the characteristics of each lake. The lakes are known to have significant effects on air masses as they move in prevailing directions, as exemplified by the ‘lake effect snow’ that falls heavily in winter on communities situated on the eastern edges of lakes. If the Lakes can frequently experience the degrees of CO2 undersaturation shown below, then the CO2 of the airmasses must be impacted as well.

WILSON, A E., D.C. GOSSIAUX, T.O. HÖÖK, J.P. Berry, P.F. LANDRUM, J. DYBLE, and S.J. Guildford. Evaluation of the human health threat associated with the hepatoxin microcystin in the muscle and liver tissues of yellow perch (Perca flavescens). Canadian Journal of Fisheries and Aquatic Sciences 65:1487-1497 (2008).

During the summer of 2006, the western basin of Lake Erie experienced a bloom of the toxigenic cyanobacterium Microcystis aeruginosa. Across 11 sites, intracellular, particulate-bound microcystin levels in the seston increased to levels that exceeded World Health Organization guidelines for drinking water exposure (1 mg toxin L–1). In contrast, toxin concentrations in yellow perch (Perca flavescens) muscle tissue (n = 68) declined from June to August, were negatively related to algal toxin levels, and never exceeded a conservative chronic exposure concentration estimated using proposed United States Environmental Protection Agency (US EPA) guidelines. Microcystin concentrations in yellow perch liver exceeded US EPA chronic exposure guidelines, were on average 125 times higher than muscle toxin concentrations per unit dry weight, and varied little throughout the summer. With current guidelines, humans do not appear to be at risk when consuming the muscle tissue of Lake Erie yellow perch collected during large-scale cyanobacterial blooms. However, this study highlights the need for a better understanding of the trophic transfer of cyanobacterial toxins through aquatic food webs in diverse ecosystems with an emphasis on understanding if these compounds could accumulate sufficiently to affect human health.

Wynne, T.T., R.P. Stumpf, M.C. Tomlinson, R.A. Warner, P.A. Tester, J. DYBLE, and G L. FAHNENSTIEL. Relating spectral shape to cyanobacterial blooms in the Laurentian Great Lakes. International Journal of Remote Sensing 29(12):3665-3672 (2008).

A change in the spectral shape at 681 nm is used to distinguish blooms of cyanobacteria from blooms of other phytoplankton via MERIS satellite sensor imagery. During large cyanobacterial blooms, the spectral shape around 681 nm is not a positive quantity as scattering due to cyanobacteria overwhelms the fluorescence signal, thus creating a negative spectral shape. This relationship is consistent in both remotely sensed and in situ data.

ZHANG, H., D.A. Culver, and L. Boegman. A two-dimensional ecological model of Lake Erie: Application to estimate dressenid impacts on large lake plankton populations. Ecological Modelling 214:219-241 (2008).

We constructed a complex ecological model of Lake Erie, EcoLE, based on a two-dimensional hydrodynamic and water quality model (CE-QUAL-W2).We used data from 1997 to calibrate the model, and data from 1998 and 1999 to verify it. The simulated surface and bottom water temperatures show good agreement with field observations. In spite of limitations of this 2D model and data availability, the simulated values of biological and nutrient state variables match well with field measurements. Although EcoLE’s performance for the verification years is as good as that of the calibration year, the wide standard deviations of both field measurements and model simulations as well as the complexity of an ecosystem of this size make us consider our model more as a valid analytical tool rather than a predictive one at this moment. Nevertheless, we have constructed the first fine-scale dynamic ecological model of a large lake that couples hydrodynamics and detailed food web of lower trophic levels and is driven by real-time air temperature and wind conditions and the inputs from the atmosphere and tributaries. Using the model we investigate the impacts of zebra mussels (Dreissena polymorpha) and quagga mussels (D. bugensis) on phytoplankton of Lake Erie. The simulation results show that dreissenid grazing impacts on non-diatom edible algae (NDEA) are weakened by the boundary layer above the basin bottom. However, dreissenid grazing impacts on diatoms are less affected by the boundary layer due to the higher sinking rates of diatoms. Dreissenid mussels increase non-diatom inedible algae (NDIA) rapidly with increasing mussel population size, because the dreissenid population excretes a large amount of ammonia and phosphate. Our results indicate that dreissenid mussels have weak direct grazing impacts on algal biomass, while indirect effects of their nutrient excretion have a greater impact on the system.

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