GLERL Publications with Abstracts

January 2011 - December 2011

Alves, J.H., A. Chawla, H.L. Tolman, D.J. SCHWAB, G.A. LANG, and G. Mann. The Great Lakes wave model at NOAANCEP: challenges and future developments. 12th International Workshop on Wave Hindcasting and Forecasting, Kohala Coast, Hawaii, October 30, 2011 - November 4, 2011. Environment Canada, the Canadian Federal Program of Energy R&D, and the WMO/IOC Joint Technical Commission for Oceanography and Marine Meteorology (JCOMM), 6 pp. (2011).

In spite of a notion that the nature of wind waves in the Great Lakes is generally benign, intense storms and rapidly changing weather patterns generate severe sea states that develop into serious hazards to marine activities involving commercial and recreational vessels. The Great Lakes basin aggregates more than 1/10th and ¼ of the populations of United States and Canada, respectively. Several states with large contributions to the American economy, such as Wisconsin and Minnesota, make up the lakes margin. Commercial shipping constitutes one of the most costeffective means of transporting raw materials and goods to and from these states, as well as provides an important source of jobs for the region’s population. Providing accurate forecasts of wind waves associated with severe sea states is a critical service towards ensuring the safety of maritime operations in the Great Lakes, with critical consequences to the American economy and public safety.

ANDERSON, E.J., and M.S. Phanikumar. Surface storage dynamics in large rivers: Comparing three-dimensional particle transport, one-dimensional fractional derivative, and multirate transient storage models. Water Resources Research 47(W09511):15 pp. (DOI:10.1029/2010WR010228) (2011).

[1] Large rivers are major conduits for sediment and nutrient transport and play an important role in global biogeochemical cycles. While smaller rivers received attention in recent decades for hyporheic exchange and nutrient uptake, fewer studies have focused on the dynamics of surface storage zones in large rivers. We investigate transport dynamics in the St. Clair River, an international river straddling the U.S.–Canadian border, using a combination of modeling and dye tracer studies. We describe a calibrated three-dimensional hydrodynamic model to generate (synthetic) breakthrough data to evaluate several classes of 1-D solute transport models for their ability to describe surface storage dynamics. Breakthrough data from the 3-D particle transport model exhibited multimodal behavior and complex dynamics that could not be described using a single first-order exchange coefficient—an approach often used to describe surface storage in transient storage models for small rivers. The 1-D models examined include multirate transient storage (MRTS) models in which storage zones were arranged either in series or parallel as well as 1-D models based on fractional derivatives. Results indicate that for 1-D models to describe data adequately, the timing of solute pulses that correspond to various in-channel features such as sandbars, islands or meander bends should be taken into account. As a result, the MRTS model with storage zones arranged in series (i.e., exchange rates triggered sequentially) provided the best description of the data. In contrast, fractional derivative models that assume storage zones were arranged in parallel failed to capture the multimodal nature of the breakthrough curves.

ANDERSON, E.J., and D.J. SCHWAB. Relationships between wind-driven and hydraulic flow in Lake St. Clair and the St. Clair River Delta. Journal of Great Lakes Research 37(1):147-158 (2011).

A three-dimensional hydrodynamic forecasting model of the Great Lakes Huron–Erie Corridor is used to investigate mixing and the relationship between hydraulic and wind-induced currents in a shallow lake system in which lake inflows come through several channels of a river delta. The hydrodynamics in Lake St. Clair and the channels of the St. Clair River Delta are evaluated for (1) a one-year simulation from 1985 including water age calculation, (2) 8 different wind direction scenarios, and (3) a storm event. Observations and model simulations show distinct regions in the lake in which currents are forced by either hydraulic flow from the river system or from wind stress over the lake. However, during severe storm events, these regions are found to shift or even disappear due to changes in the delta channel inputs into the lake. These changes underscore the need for realistic, unsteady river flow boundary conditions at interfaces between a shallow lake and river delta. Steady inflow conditions will not allow for potential shifting of these current zones, and will also fail to resolve flow retardation or reversals during storm events.

Arend, K.K., D. BELETSKY, J.V. DePinto, S.A. Ludsin, J.J. ROBERTS, D.K. Rucinski, D. Scavia, D.J. SCHWAB, and T.O. Hook. Seasonal and interannual effects of hypoxia on fish habitat quality in central Lake Erie. Freshwater Biology 56(2):366-383 DOI:10.111/J.1365-2427.2010.02504.X) (2011).

1. Hypoxia occurs seasonally in many stratified coastal marine and freshwater ecosystems when bottom dissolved oxygen (DO) concentrations are depleted below 2–3 mg O2 L-1.
2. We evaluated the effects of hypoxia on fish habitat quality in the central basin of Lake Erie from 1987 to 2005, using bioenergetic growth rate potential (GRP) as a proxy for habitat quality. We compared the effect of hypoxia on habitat quality of (i) rainbow smelt, Osmerus mordax mordax Mitchill (young-of-year, YOY, and adult), a cold-water planktivore, (ii) emerald shiner, Notropis atherinoides Rafinesque (adult), a warm-water planktivore, (iii) yellow perch, Perca flavescens Mitchill (YOY and adult), a cool-water benthopelagic omnivore and (iv) round goby Neogobius melanostomus Pallas (adult) a eurythermal benthivore. Annual thermal and DO profiles were generated from 1D thermal and DO hydrodynamics models developed for Lake Erie’s central basin.
3. Hypoxia occurred annually, typically from mid-July to mid-October, which spatially and temporally overlaps with otherwise high benthic habitat quality. Hypoxia reduced the habitat quality across fish species and life stages, but the magnitude of the reduction varied both among and within species because of the differences in tolerance to low DO levels and warm-water temperatures.
4. Across years, trends in habitat quality mirrored trends in phosphorus concentration and water column oxygen demand in central Lake Erie. The per cent reduction in habitat quality owing to hypoxia was greatest for adult rainbow smelt and round goby (mean: -35%), followed by adult emerald shiner (mean: -12%), YOY rainbow smelt (mean: -10%) and YOY and adult yellow perch (mean: -8.5%).
5. Our results highlight the importance of differential spatiotemporally interactive effects of DO and temperature on relative fish habitat quality and quantity. These effects have the potential to influence the performance of individual fish species as well as population dynamics, trophic interactions and fish community structure.

BAI, X., J. WANG, D. Liu, D. Wang, and Y. Liu. Severe ice conditions in the Bohai Sea, China and mild ice conditions in the Great Lakes during the 2009/2010 winter: Links to El Nino and a strong negative Arctic Oscillation. Journal of Applied Meteorology and Climatology 50:1922-1935 (DOI: 10.1175/2011JAMC2675.1) (2011).

This study investigates the causes of severe ice conditions over the Bohai Sea, China, and mild ice cover over the North American Great Lakes under the same hemispheric climate patterns during the 2009/10 winter with a strong negative Arctic Oscillation (AO) and an El Nino event. The main cause of severe ice cover over the Bohai Sea was the strong negative AO. Six of seven winters with severe ice were associated with a strong negative AO during the period 1954–2010. The Siberian high (SH) in the 2009/10winterwas close to normal. The influence of El Nino on the Bohai Sea was not significant. In contrast, the mild ice conditions in the Great Lakes were mainly caused by the strong El Nino event. Although the negative AO generally produces significant colder surface air temperature (SAT) and heavy ice cover over the Great Lakes, when it coincided with a strong El Nino event during the 2009/10 winter the El Nino-induced Pacific–North America (PNA)-like pattern dominated the midlatitudes and was responsible for the flattening of the ridge–trough system over North America, leading to warmer-than-normal temperatures and mild ice conditions over the Great Lakes. This comparative study revealed that interannual variability of SAT in North America, including the Great Lakes, is effectively influenced by El Nino events through a PNA or PNA-like pattern whereas the interannual variability of SAT in northeastern China, including the Bohai Sea area, was mainly controlled by AO and SH.

Brandt, S.B., M. Costantini, S.E. Kolesar, S.A. Ludsin, D.M. MASON, C.M. Rae, and H. ZHANG. Does hypoxia reduce habitat quality for Lake Erie walleye (Sander vitreus)? A bioenergetics perspective. Canadian Journal of Fisheries and Aquatic Sciences 68:857-879 (DOI:10.1139/F2011-018) (2011).

In Lake Erie, the duration and extent of hypoxia (dissolved oxygen (DO) ≤ 2 mg·L–1) has increased in recent years, yet little is known on the corresponding impact on its fish, particularly the highly valued walleye (Sander vitreus) fishery. Here, we quantified the impact of hypoxia on walleye habitat quality, using a spatially explicit growth rate potential (GRP) modeling approach, which integrates the spatial arrangement of biological (prey availability) and environmental (DO, temperature, irradiance) measures. Data were collected along two types of transects: 60 km north–south transects (each sampled once during day and night) and 5 km east–west transects (sampled every 4 h for 24 h) during August (prehypoxia), September (peak-hypoxia), and October (post-hypoxia) 2005. Overall, the average monthly amount of high quality habitat (GRP > 0 g·g–1·day–1) for walleye declined slightly with hypoxia (<2.0%); however, hypoxia appeared to enhance habitat quality by concentrating prey in favorable temperature, DO, and light conditions. In September, percentages of walleye growth rates were at the upper end of the range, much more so than during August or October. Although an understanding of walleye distributions, foraging, and growth in relation to hypoxia is needed, our results do not suggest that hypoxia is negatively influencing walleye through reduced habitat quality.

BURTNER, A.M., P.B. McIntyre, J.D. Allan, and D.R. Kashian. The influence of land use and potamodromous fish on ecosystem function in Lake Superior tributaries. Journal of Great Lakes Research 37:521-527 (DOI:10.1016/j.jglr.2011.05.014) (2011).

Allochthonous nutrients and carbon are recognized as dominant controls on biogeochemistry of low-order streams. In some systems, potamodromous fish may provide a complementary source of material as they deliver lake-derived materials to spawning streams. This study examines nutrient and carbon inputs from terrestrial ecosystems and migratory fishes to streams in undeveloped watersheds in northern Michigan, USA. We compared watershed and riparian area, slope, and landcover to nutrient concentrations at 26 sites, as well as whole-stream metabolism at 5 sites. Despite low levels of agricultural land use (0–3%), agriculture had the largest influence on stream chemistry as indicated by higher dissolved organic carbon (DOC), ammonium, silica, and chloride concentrations at the watershed level, and increased DOC and chloride at the riparian level. Ecosystem respiration and net primary production increased with watershed and riparian area, and the proportion of managed forest. To quantify inputs from fish, we monitored the spawning migrations of white (Catostomus commersonii) and longnose (C. catostomus) suckers at one site, and measured nutrients and stream metabolism above and below an impassable dam. Nutrient concentrations were uniformly low and did not increase during the fish migration; however, temporal shifts in stream metabolism during sucker migration suggest that fish influenced respiration, presumably by providing high-quality carbon and bioavailable nutrients. We conclude that both watershed land use and fish migrations provide important sources of allochthonous material to these oligotrophic streams. Recognizing the bi-directional nature of allochthonous inputs is important for understanding controls on ecosystem functioning in low-order streams.

Cha, Y.K., C.A. STOW, T.F. NALEPA, and K.H. Reckhow. Do invasive mussels restrict offshore phosphorus transport in Lake Huron? Environmental Science & Technology 45:6 pp. (DOI: 10.1021/es2014715) (2011).

Dreissenid mussels were first documented in the Laurentian Great Lakes in the late 1980s. Zebra mussels (Dreissena polymorpha) spread quickly into shallow, hard-substrate areas; quagga mussels (Dreissena rostriformis bugensis) spread more slowly and are currently colonizing deep, offshore areas. These mussels occur at high densities, filter large water volumes while feeding on suspended materials, and deposit particulate waste on the lake bottom. This filtering activity has been hypothesized to sequester tributary phosphorus in nearshore regions reducing offshore primary productivity. We used a mass balance model to estimate the phosphorus sedimentation rate in Saginaw Bay, a shallow embayment of Lake Huron, before and after the mussel invasion. Our results indicate that the proportion of tributary phosphorus retained in Saginaw Bay increased from approximately 46 to 70% when dreissenids appeared, reducing phosphorus export to the main body of Lake Huron. The combined effects of increased phosphorus retention and decreased phosphorus loading have caused an approximate 60% decrease in phosphorus export from Saginaw Bay to Lake Huron. Our results support the hypothesis that the ongoing decline of preyfish and secondary producers including diporeia (Diporeia spp.) in Lake Huron is a bottom-up phenomenon associated with decreased phosphorus availability in the offshore to support primary production.

Conroy, J.D., L. Boegman, H. ZHANG, W.J. Edwards, and D.A. Culver. "Dead zone" dynamics in Lake Erie: The importance of weather and sampling intensity for calculated hypolimnetic oxygen depletion rates. Aquatic Sciences 73:289-304 (DOI:10.1007/s00027-010-0176-1) (2011).

Calculated hypolimnetic oxygen depletion (HOD) rates depend not only on environmental factors but also logistical ones. In particular, lack of understanding of the effects of weather in addition to how sampling effort determines calculated HOD rates complicates ecological understanding and environmental management of lake ecosystems. To better determine the roles of weather and sampling effort, we combined (1) weekly measurements of temperature and dissolved oxygen (DO) concentrations from seven stations in the Sandusky subbasin of Lake Erie’s central basin during 2005, (2) contemporaneous measures of storm activity and tributary discharge, and (3) a two-dimensional coupled hydrodynamic, chemical, and biological model of Lake Erie to investigate (1) how increased storm activity and tributary discharge affected short- (daily) and long-term (seasonal) dynamics of hypolimnetic hypoxia, and (2) how spatial (number of sites sampled) and temporal (sampling frequency) sampling effort affected calculated HOD rates. Our model closely replicated field-observed DO dynamics. When comparing baseline modeled dynamics to those in a second simulation with twice the number of days with high winds, however, we found that with more storm activity (1) periods of entrainment became more frequent, (2) the hypolimnion was warmer, (3) thermal stratification occurred 1 month later, whereas autumnal turnover occurred at least 1 week earlier shortening the duration of stratification by 1–2 months, and (4) HOD rates increased 12%. Further, spatial and temporal sampling intensity also affected calculated HOD rates. Consequently, adequately quantifying actual HOD rates requires sufficient sampling effort and the particular role of weather should be assessed with rigorous field and simulation studies, especially if HOD rates are used to indicate management success.

Crane, D.P., T.F. JOHENGEN, and J.D. Allan. Assessment of quantitative food web metrics for investing the influence of land use on warm water fish diets. Hydrobiologia 664:1-15 (2011).

Lotic systems in many regions of the country have experienced habitat degradation and biodiversity loss due to agricultural activity and urbanization. Southeastern Michigan is no exception, as agriculture in the River Raisin watershed and increased urbanization in the Huron River watershed threatens both systems. To further understand the ecological impact of land use on trophic interactions in Midwestern streams and assess the use of a selected set of weighted, quantitative food web metrics as a tool for investigating the influence of anthropogenic disturbance on these systems we compared summer food webs for nine second-order streams. All streams were categorized as developed, undeveloped, or agricultural based on land cover data. Developed and undeveloped streams were located in the Huron River watershed and agricultural streams were located in the River Raisin watershed. Reach-level habitat quality was also assessed at each study site using the EPA’s Rapid Habitat Assessment. Fish diets (n = 410) were analyzed to create summer food webs for each site. Comparisons of food webs were made using a suite of weighted, quantitative metrics to identify differences in fish–macroinvertebrate interactions across streams with differing land cover at the sub-basin scale and habitat quality at the local scale. Although undeveloped streams had higher species richness and less habitat degradation, no significant patterns were observed in the quantitative metrics across the three stream categories or based on reach-level habitat conditions. Decapoda, terrestrial Hymenoptera, and Chironomidae were the primary prey taxa in all stream categories. Decapods accounted for the majority of biomass consumed and the pattern of this consumption strongly influenced metric scores. The suite of quantitative metrics tested in this study did not detect significant differences in fish–macroinvertebrate food webs across land use categories, likely in part due to the dominance of a large, tolerant prey taxa in fish diets, regardless of land use and local habitat quality.

Cross, V.A., J.F. BRATTON, C.W. Worley, J. Crusius, and K.D. Kroeger. Continuous resistivity profiling data from the Corsica River Estuary, Maryland. USGS Open File Report 2010-1094. U.S. Geological Survey, Woods Hole, MA (2011).

Submarine groundwater discharge (SGD) into Maryland's Corsica River Estuary was investigated as part of a larger study to determine its importance in nutrient delivery to the Chesapeake Bay. The Corsica River Estuary represents a coastal lowland setting typical of much of the eastern bay. An interdisciplinary U.S. Geological Survey (USGS) science team conducted field operations in the lower estuary in April and May 2007. Resource managers are concerned about nutrients that are entering the estuary via SGD that may be contributing to eutrophication, harmful algal blooms, and fish kills. Techniques employed in the study included continuous resistivity profiling (CRP), piezometer sampling of submarine groundwater, and collection of a time series of radon tracer activity in surface water. A CRP system measures electrical resistivity of saturated subestuarine sediments to distinguish those bearing fresh water (high resistivity) from those with saline or brackish pore water (low resistivity). This report describes the collection and processing of CRP data and summarizes the results. Based on a grid of 67.6 kilometers of CRP data, low-salinity (high-resistivity) groundwater extended approximately 50–400 meters offshore from estuary shorelines at depths of 5 to >12 meters below the sediment surface, likely beneath a confining unit. A band of low-resistivity sediment detected along the axis of the estuary indicated the presence of a filled paleochannel containing brackish groundwater. The meandering paleochannel likely incised through the confining unit during periods of lower sea level, allowing the low-salinity groundwater plumes originating from land to mix with brackish subestuarine groundwater along the channel margins and to discharge. A better understanding of the spatial variability and geological controls of submarine groundwater flow beneath the Corsica River Estuary could lead to improved models and mitigation strategies for nutrient over-enrichment in the estuary and in other similar settings.

DeMarchi, C., F. Xing, T.E. CROLEY II, C. He, and Y.P. Wang. Application of a distributed large basin runoff model to Lake Erie: Model calibration and analysis of parameter spatial variation. Journal of Hydrologic Engineering 16(3):193-202 DOI: 10.1061/(ASCE)HE.1943-5584.0000.304) (2011).

The distributed large basin runoff model (DLBRM) was designed to simulate the hydrological processes of the Great Lakes watersheds. As part of its development, the DLBRM was recently applied to 18 watersheds in the Lake Erie basin, where it was first calibrated to reproduce the observed discharge in 1950–1964 and then applied to 1999–2006. Four different calibration objective functions: root mean squared error (RMSE) minimization, mean absolute error (MAE) minimization, correlation maximization, and Nash-Sutcliffe index maximization were tested, revealing RMSE minimization as the most successful method and able to achieve results very close to its global minimum. Further, the distribution of the main DLBRM parameters in the 18 watersheds was consistent with regional patterns, although each watershed was calibrated individually, thus adding credibility to the calibration process. Model performances, while generally good, varied across the basin according to a series of environmental factors, including climate, watershed shape, topography, and land cover and observation factors such as gauging station distribution. Gauging station coverage proved to be extremely important in the ability of the model to track flow variability. The DLBRM proved to be able to replicate well the 1999–2006 hydrologies of most watersheds without recalibration. However, its performance declined in heavily urbanized watersheds, where the landscape changed the most. The results described in this paper will lead to improved model performance and increased practical applications of the DLBRM, providing important information to researchers and decision makers for efficient water management programs in Great Lakes watersheds. DOI: 10.1061/(ASCE) HE.1943-5584.0000304.

Evans, M.A., G.L. FAHNENSTIEL, and D. Scavia. Incidental oligotrophication of North American Great Lakes. Environmental Science and Technology 45:3297-3303 (DOI 10.1021/es103892w) (2011).

Phytoplankton production is an important factor in determining both ecosystem stability and the provision of ecosystem goods and services. The expansive and economically important North American Great Lakes are subjected to multiple stressors and understanding their responses to those stresses is important for understanding system-wide ecological controls. Here we show gradual increases in spring silica concentration (an indicator of decreasing growth of the dominant diatoms) in all basins of Lakes Michigan and Huron (USA and Canadian waters) between 1983 and 2008. These changes indicate the lakes have undergone gradual oligotrophication coincident with and anticipated by nutrient management implementation. Slow declines in seasonal drawdown of silica (proxy for seasonal phytoplankton production) also occurred, until recent years, when lake-wide responses were punctuated by abrupt decreases, putting them in the range of oligotrophic Lake Superior. The timing of these dramatic production drops is coincident with expansion of populations of invasive dreissenid mussels, particularly quagga mussels, in each basin. The combined effect of nutrient mitigation and invasive species expansion demonstrates the challenges facing large-scale ecosystems and suggest the need for new management regimes for large ecosystems.

Glynn, P., L. Jacobsen, G. Phelps, G. Bawden, V. Grauch, F. Orndort, R. Winston, M. Fienen, M. Cross, and J.F. BRATTON. 3D/4D modelling, visualization and information frameworks: Current U.S. Geological Survey practice and needs. In Three-Dimensional Geological Mapping; Workshop Extended Abstracts. H.A.J. Russell, R.C. Berg, and L.H. Thorleifson (eds.). Geological Survey of Canada Open File 6998, 33-38 pp. (DOI:10.4095/289609) (2011).

Progress is being made in the ability to visualize and model geologic data and information in 3 spatial dimensions (3D) and sometimes adding time for 4 dimensions (4D). These abilities are enriching the conceptual models and process simulations constructed by geologists and hydrogeologists. Computer technology is also enhancing the visualization and modeling of landscapes and the hydrodynamic simulations of surface waters. Progress needs to be made in visualizing and coupling geologic, hydrologic, atmospheric, and biologic processes together into 3D/4D information frameworks that encompass and integrate observations and simulations across a diversity of spatial and temporal scales and data types. Achieving progress in these areas will also enhance the relevance and effective communication of USGS science to policy makers and to the lay public.

GRONEWOLD, A.D., A.H. CLITES, T.S. HUNTER, and C.A. STOW. An appraisal of the Great Lakes Advanced Hydrologic Prediction System. Journal of Great Lakes Research 37(3):577-583 (DOI:10.1016/j.jglr.2011.06.010) (2011).

Great Lakes water level forecasts are used to inform decisions ranging from personal choices of recreational activities to corporate evaluations of alternative cargo transport options. For effective decision-making it is important that these model-based forecasts include an accurate expression of the forecast uncertainty, as well as information regarding the model forecasting skill. We provide an assessment of water level forecasts from 1997 through 2009 that were made using the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory (GLERL) Advanced Hydrologic Prediction System (AHPS). A visual comparison between observed and forecast water levels suggests that AHPS generally captures seasonal and inter-annual patterns. A more quantitative assessment based on the percentage of observations within 90% prediction intervals, however, indicates that AHPS generally underestimates the observed variability of Great Lakes water levels. This assessment provides a benchmark for forecast performance against which alternative model structures (including future evolutions of AHPS) can be tested, and a basis to identify and prioritize the implementation of those alternatives. Including a calibrated model error term into the AHPS framework, to accommodate the underestimated variability, is a priority for short-term development and research, and represents one step toward more accurately quantifying forecast uncertainty. Our results also underscore the importance of storing historical forecasts and the data from which they were derived to serve as a basis for assessing model performance and prioritizing future model improvements.

He, C., and T.E. CROLEY II. Hydrologic resource sheds and the U.S. Great Lakes applications. Journal of Resources and Ecology 1(1):1-9 (2010).

This article describes a relatively new concept, “hydrological resource shed”: a geographic area that contributes material (e.g. water, nutrients, and sediments) over one time interval, passing through a location of interest over another time interval. It discusses the unique features and potential applications of the hydrologic resource sheds for incorporating space-time variability in discovering, understanding, and simulating the transport and distribution of water and materials across multiple space and time scales. An example is presented for computing the hydrologic resource shed distributions using a hydrologic model, Distributed Large Basin Runoff Model (DLBRM) in the Maumee River watershed in western Lake Erie Basin of the U.S.

HONDORP, D.W., S.A. POTHOVEN, and S.B. Brandt. Feeding selectivity of slimy sculpin Cottus cognatus and deepwater sculpin Myoxocephalus thompsonii in southeast Lake Michigan: Implications for species coexistence. Journal of Great Lakes Research 37:165-172 (2011).

Feeding selectivity was compared between slimy sculpin Cottus cognatus and deepwater sculpin Myoxocephalus thompsonii collected from southeast Lake Michigan during 1999–2002 to evaluate the hypothesis that differential prey selection contributes to long-term coexistence of these species. Study results indicated that slimy and deepwater sculpin select different prey types and sizes. Selection for the shrimp-like crustacean Mysis diluviana was consistently greater for deepwater sculpin than for slimy sculpin, whereas selection for the amphipod Diporeia spp. was higher for slimy sculpin than for deepwater sculpin when Mysis was the only other available prey type. Slimy sculpin also exhibited higher selectivity for chironomids (order Diptera, family Chironomidae) compared with deepwater sculpin. Patterns in food resource partitioning were consistent between sampling periods covering different locations, seasons and depths, as well as between locations with varying levels of Diporeia availability. This consistency suggests (1) that differences in food use by the two species are associated with intrinsic differences in food preferences or feeding behaviors and (2) that Diporeia declines had not fundamentally altered the resource partitioning dynamics of the two species as of 2002. The results also indicated that slimy and deepwater sculpin can partition food resources on the basis of prey size since deepwater sculpin tended to select larger Diporeia than slimy sculpin. Differences in prey selection may mediate competitive interactions between slimy and deepwater sculpin directly by reducing diet overlap in areas of sympatry or indirectly by causing these fish to select different depth habitats.

HU, H., J. WANG, and D. Wang. A model-data study of the 1999 St. Lawrence Island polynya in the Bering Sea. Journal of Geophysical Research 116(C12018):17 (DOI:10.1029/2011JC007309) (2011).

A Coupled Ice Ocean Model (CIOM) and in situ measurements were used to investigate sea ice and the St. Lawrence Island polynya (SLIP) in the Bering Sea in 1999. The modeled 1999 seasonal cycle of ice cover compared well with satellite measurements. The simulated maximum sea ice coverage was ∼0.8 × 106 km2, and the simulated maximum sea ice volume was ∼344 km3. The polynya south of St. Lawrence Island was captured by the CIOM and investigated in depth against the measurements. It was found that an offshore wind was necessary, but not sufficient on its own, for the development of the SLIP. It was found that a strong offshore wind, offshore surface water velocity, and the angle (<60°) between wind and water current are the three major factors for the development of the SLIP. Multiple-variable, linear regression models were developed to confirm these three mechanisms. Yearly potential sea ice production in the SLIP area was estimated to be about 95.7 km3, which accounts for 2.8% of the total potential production of 3393 km3 in the whole Bering Sea. Sea ice contributes to approximately 63% of winter salinity changes in the Bering Shelf (<200 m), while the SLIP can contribute more than twice the local salinity changes. The relationships among wind, sea ice, and surface ocean current were examined. The classic Ekman drift theory (that surface water velocity drifts 45° to the right of the wind direction) is modified to be 50.4° on the ice-covered Bering Shelf due to the year-round existence of a background northward ocean transport.

Ivan, L.N., E.S. RUTHERFORD, and T.H. JOHENGEN. Impacts of adfluvial fish on the ecology of two Great Lakes tributaries. Transactions of the American Fisheries Society 140:1670-1682 (DOI:10.1080/00028487.2011.642233) (2011).

Anadromous and adfluvial fish can transport high concentrations of nutrients and energy into streams during spawning runs. While the ecological effects of their spawning migrations are variable, in some instances these fish contribute to increased nutrient concentrations, primary productivity, invertebrate biomass, and resident fish growth and survival in the nutrient-poor streams of the Pacific Northwest. In tributaries of the Great Lakes, the effects of introduced salmonid and native adfluvial fish are poorly documented. We conducted field experiments to determine the effects of a semelparous fall fish, Chinook salmon Oncorhynchus tshawytscha, and an iteroparous spring fish, steelhead O. mykiss, on the ecology and productivity of two tributaries to the Muskegon River, Michigan, a Lake Michigan tributary. We sampled stream biota and water chemistry before and after the introduction of Chinook salmon carcasses and eggs in the fall and steelhead eggs in the spring in a tributary stream with natural spawning runs and in another tributary stream without runs but with carcass and egg additions. There was no response in terms of invertebrate density or water chemistry to spawning migrations or salmon carcass introductions in either tributary. The density of resident brown trout Salmo trutta increased in both stream types after the introduction of salmon carcasses in the fall, and energy consumption increased after the addition of salmon eggs in the fall and spring in the manipulated stream. Based on stomach content analysis, fish that had eggs in their stomachs also consumed more energy than fish that did not consume eggs. The results suggest that adfluvial fish may affect some tributaries of the Great Lakes by providing high-energy food sources to resident stream fish, but the potential effect of this egg consumption on resident fish growth and survival requires more research

KRUEGER, D.M., E.S. RUTHERFORD, and D.M. MASON. Influence of predation mortality on survival of Chinook salmon parr in a Lake Michigan tributary. Transactions of the American Fisheries Society 140:147-163 (2011).

Predation mortality among Chinook salmon Oncorhynchus tshawytscha parr can act at small spatiotemporal scales and cause variability in parr survival and potential recruitment. We analyzed predator diets and multiplied per capita consumption rates by predator population estimates to evaluate the relative effect of predation by stocked sport fishes on the variability in survival of Chinook salmon parr in the Muskegon River, Michigan, from 2004 to 2007. Brown trout Salmo trutta were a major predator of Chinook salmon parr, consuming from 15% to 34% of the total number available, while walleyes Sander vitreus consumed from 0.2% to 15%. Walleyes also consumed large quantities of brown trout and rainbow trout O. mykiss. Brown trout predation on Chinook salmon parr was largely dependent on parr size, while walleye predation was buffered by the availability of rainbow trout and brown trout. Predation mortality appeared to be responsible for a more than three-fold difference in the survival of Chinook salmon parr in the Muskegon River. The vulnerability of Chinook salmon parr to predation appeared to be controlled by parr growth rates, brown trout stocking dates, and the number of brown trout stocked. Fishery regulations to manipulate piscivore abundance may lead to higher survival and lower variability in the survival of Chinook salmon parr.

LIU, P.C. Corrigendum to Brief Communication "What do we know about freaque waves in the ocean and lakes and how do we know it?" published in Nat. Hazards Earth Syst. Sci., 10, 2919-2196, 2010. Natural Hazards Earth System Science 11:331-332 (DOI: 10.5194/nhess-11-331-2011) (2011).

I have received an email communication from L. Cavaleri (2011) regarding our recent Brief Communication in Nat. Hazards Earth Syst. Sci., 10, 2191–2196, doi:10.5194/nhess- 10-2191-2010, 2010 “What do we know about freaque waves in the ocean and lakes . . .” with this comment:“I must correct you on one point. At the bottom of the second page and beginning of the third one you quote the report of a young sailor about the “thundering through .... deafening roar” of the incoming freak (or freaque if you prefer) wave, and you say that this “is a new, never previously mentioned characterization of a freaque wave”. Well, this is not true. (Emphasize added.)”

Liu, G.B., G.B. Arhonditsis, C.A. STOW, and D. Scavia. Predicting the hypoxic-volume in Chesapeake Bay with the Streeter-Phelps model: A Bayesian approach. Journal of the American Water Resources Association 47(6):1348-1363 (DOI:10.1111/j.1752-1688.2011.00588.x) (2011).

Hypoxia is a long-standing threat to the integrity of the Chesapeake Bay ecosystem. In this study, we introduce a Bayesian framework that aims to guide the parameter estimation of a Streeter–Phelps model when only hypoxic volume data are available. We present a modeling exercise that addresses a hypothetical scenario under which the only data available are hypoxic volume estimates. To address the identification problem of the model, we formulated informative priors based on available literature information and previous knowledge from the system. Our analysis shows that the use of hypoxic volume data results in reasonable predictive uncertainty, although the variances of the marginal posterior parameter distributions are usually greater than those obtained from fitting the model to dissolved oxygen (DO) profiles. Numerical experiments of joint parameter estimation were also used to facilitate the selection of more parsimonious models that effectively balance between complexity and performance. Parameters with relatively stable posterior means over time and narrow uncertainty bounds were considered as temporally constant, while those with time varying posterior patterns were used to accommodate the interannual variability by assigning year-specific values. Finally, our study offers prescriptive guidelines on how this model can be used to address the hypoxia forecasting in the Chesapeake Bay area.

LOFGREN, B.M., T.S. HUNTER, and J. Wilbarger. Effects of using air temperature as a proxy for potential evapotranspiration in climate change scenarios of Great Lakes basin hydrology. Journal of Great Lakes Research 37:9 pp. (DOI:10.1016/j.jglr.2011.09.006) (2011).

Hydrologic impacts of climate change are regularly assessed with hydrologic models that use air temperature as a proxy to compute potential evapotranspiration (PET). This approach is taken in the Large Basin Runoff Model (LBRM), which has been used several times for calculation of the runoff from the terrestrial part of the Great Lakes basin under climate change scenarios, with the results widely cited. However, a balance between incoming and outgoing energy, including the latent heat of evaporation, is a fundamental requirement for a land surface, and is not enforced under this approach. For calculating PET and evapotranspiration (ET) in climate change scenarios, we use an energy budget-based approach to adjusting the PET as an alternative that better satisfies conservation of energy. Using this new method, the increase in ET under enhanced greenhouse gas concentrations has reduced magnitude compared to that projected using the air temperature proxy. This results in either a smaller decrease in net basin supply and smaller drop in lake levels than using the temperature proxy, or a reversal to increased net basin supply and higher lake levels. An additional reason not to rely on a temperature proxy relation is that observational evidence demonstrates that the correlation between air temperature and ET (or PET) is restricted to the mean annual cycle of these variables. This brings into question the validity of air temperature as a proxy for PET when considering non-annual variability and secular changes in the climate regime.

Madenjian, C.P., E.S. RUTHERFORD, M. Blouin, B.J. Sederberg, and J.R. Elliott. Spawning habitat unsuitability: An impediment to Cisco rehabilitatiaon in lake Michigan? Journal of North American Fisheries Management 31:905-913 (DOI:10.1080/02755947.2011.632065) (2012).

The cisco Coregonus artedi was one of the most important native prey fishes in Lake Michigan and in the other four Laurentian Great Lakes. Most of the cisco spawning in Lake Michigan was believed to have occurred in Green Bay. The cisco population in Lake Michigan collapsed during the 1950s, and the collapse was attributed in part to habitat degradation within Green Bay.Winter water quality surveys of lower Green Bay during the 1950s and 1960s indicated that the bottom dissolved oxygen (DO) concentration was less than 2 mg/L throughout much of the lower bay, and most cisco eggs would not successfully hatch at such low DO concentrations. To determine present-day spawning habitat suitability in lower Green Bay, we compared cisco egg survival in lower Green Bay with survival at a reference site (St. Marys River, Michigan–Ontario) during 2009. We also conducted winter water quality surveys in lower Green Bay and the St. Marys River during 2009 and 2010. Cisco egg survival in lower Green Bay averaged 65.3%, which was remarkably similar to and not significantly different from the mean at the St. Marys River site (64.0%). Moreover, the lowest bottom DO concentrations recorded during the winter surveys were 11.2 mg/L in lower Green Bay and 12.7 mg/L in the St. Marys River. These relatively high DO concentrations would not be expected to have any negative effect on cisco egg survival. We conclude that winter water quality conditions in lower Green Bay were suitable for successful hatching of cisco eggs and that water quality during the egg incubation period did not represent an impediment to cisco rehabilitation in Lake Michigan. Our approach to determining spawning habitat suitability for coregonids would be applicable to other aquatic systems.

Madenjian, C.P., M.A. Stapanian, L.D. Witzel, D.W. Einhouse, S.A. POTHOVEN, and H.L. Whitford. Evidence for predatory control of the invasive round goby. Biological Invasions 13:987-1002 (DOI:10.1007/s10530-010-9884-7) (2011).

We coupled bioenergetics modeling with bottom trawl survey results to evaluate the capacity of piscivorous fish in eastern Lake Erie to exert predatory control of the invading population of round goby Neogobius melanostomus. In the offshore (>20 m deep) waters of eastern Lake Erie, burbot Lota lota is a native top predator, feeding on a suite of prey fishes. The round goby invaded eastern Lake Erie during the late 1990s, and round goby population size increased dramatically during 1999–2004. According to annual bottom trawl survey results, round goby abundance in offshore waters peaked in 2004, but then declined during 2004–2008. Coincidentally, round goby became an important component of burbot diet beginning in 2003. Using bottom trawling and gill netting, we estimated adult burbot abundance and age structure in eastern Lake Erie during 2007. Diet composition and energy density of eastern Lake Erie burbot were also determined during 2007. This information, along with estimates of burbot growth, burbot mortality, burbot water temperature regime, and energy densities of prey fish from the literature, were incorporated into a bioenergetics model application to estimate annual consumption of round goby by the adult burbot population. Results indicated that the adult burbot population in eastern Lake Erie annually consumed 1,361 metric tons of round goby. Based on the results of bottom trawling, we estimated the biomass of yearling and older round goby in offshore waters eastern Lake Erie during 2007–2008 to be 2,232 metric tons. Thus, the adult burbot population was feeding on round goby at an annual rate equal to 61% of the estimated round goby standing stock. We concluded that the burbot population had high potential to exert predatory control on round goby in offshore waters of eastern Lake Erie

MIEHLS, A.L.J., S.D. Peacor, and A.G. McAdam. Genetic and maternal effects on tail spine and body length in the invasive spiny water flea (Bythotrephes longimanus). Evolutionary Applications, 11 pp., (2012).

Interest in the evolution of invasive species has grown in recent years, yet few studies have investigated sources of variation in invasive species traits experiencing natural selection. The spiny water flea, Bythotrephes longimanus, is an invasive zooplankton in the Great Lakes that exhibits seasonal changes in tail spine and body length consistent with natural selection. Evolution of Bythotrephes traits, however, depends on the presence and magnitude of quantitative genetic variation, which could change within or across years. Clonal analysis of wild-captured Bythotrephes indicated that variance components for distal spine length were variable among but not within years. Spine length was always heritable but was not always influenced by maternal effects. In contrast, variance components for body length varied both within and among years, but likewise body length was always heritable and not always influenced by maternal effects. Results indicate that important Bythotrephes traits have heritable variation comparable to native species and other invasive species that would enable an evolutionary response to natural selection. This evolutionary capacity could contribute to the widespread success and dramatic effects of Bythotrephes invasion in systems with diverse biotic and abiotic conditions.

Millie, D.F., G.L. FAHNENSTIEL, G.R. Weckman, D.M. Klarer, J. DYBLE BRESSIE, H.A. VANDERPLOEG, and D.B. Fishman. An "Enviro-Informatic" assessment of Saginaw Bay (Lake Huron, USA) phytoplankton: Data-driven characterization and modeling of Microcystis (Cyanophyta). Journal of Phycology 47:714-730 (DOI: 10.1111/j.1529-8817.2011.01022.x) (2011).

Phytoplankton and Microcystis aeruginosa (Kutz.) Kutz. biovolumes were characterized and modeled, respectively, with regard to hydrological and meteorological variables during zebra mussel invasion in Saginaw Bay (1990–1996). Total phytoplankton and Microcystis biomass within the inner bay were one and one-half and six times greater, respectively, than those of the outer bay. Following mussel invasion, mean total biomass in the inner bay decreased 84% but then returned to its approximate initial value. Microcystis was not present in the bay during 1990 and 1991 and thereafter occurred at ⁄ in 52% of sample sites ⁄ dates with the greatest biomass occurring in 1994–1996 and within months having water temperatures >19_C. With an overall relative biomass of 0.03 ± 0.01 (mean + SE), Microcystis had, at best, a marginal impact upon holistic compositional dynamics. Dynamics of the centric diatom Cyclotella ocellata Pant. and large pennate diatoms dominated compositional dissimilarities both inter- and intra-annually. The environmental variables that corresponded with phytoplankton distributions were similar for the inner and outer bays, and together identified physical forcing and biotic utilization of nutrients as determinants of system-level biomass patterns. Nonparametric models explained 70%–85% of the variability in Microcystis biovolumes and identified maximal biomass to occur at total phosphorus (TP) concentrations ranging from 40 to 45 ug L-1. From isometric projections depicting modeled Microcystis ⁄environmental interactions, a TP concentration of <30 ug L-1 was identified as a desirable contemporary ‘‘target’’ for management efforts to ameliorate bloom potentials throughout mussel-impacted bay waters.

Mizobata, K., J. WANG, H. HU, and D. Wang. Low primary productivity in the Chukchi Sea controlled by wam Pacific water: A data-model fusion study. In Remote Sensing of the Changing Oceans. D. Tang (Ed.). Springer-Verlag, Berlin, 239-250 (DOI 10.1007/978-3-642-16541-2_12) (2011).

The Sea-viewing Wide Field-of-view Sensor (SeaWiFS) has identified a broad low chlorophyll-a (chl-a) area in the Chukchi Sea since 2002. High sea surface temperature from 2002 (more than 5?C), which resulted in a long duration of open water, was also detected by satellite. An intensified ocean color front at the southwest Chukchi Sea near the Siberian Coast indicates nutrient depletion in the Alaska Coastal Current and its branches. A low chl-a area started to emerge in the Hope Valley in June, and then expanded to the Herald Shoal and Hanna Shoal during July and August. The evolution pattern of low chl-a area is consistent with the variability of the pathway of the Pacific water simulated by a Coupled Ice-Ocean Model (CIOM). These results suggest that the summer phytoplankton bloom from 2002 to 2005 was suppressed by the dominance of warm nutrient-poor water from the Pacific, and by the deepening of the surface mixed layer by strong wind stress. During the summer of 2004, a phytoplankton bloom was detected at the ice edge when the sea surface wind field was relatively calm. Our results imply that the ice edge bloom was induced due to weak wind speeds, which produce shallower upper mixed layer, favoring the ice-edge bloom.

Moore, N.J., G. Alagarswamy, B.C. Pijanowski, P.K. Thornton, B.M. LOFGREN, J. Olson, J.A. Andresen, P. Yanda, and J. Qi. East African food security as influenced by future climate change and land use change at local to regional scales. Climatic Change 106:22 pp. (DOI: 10.1007/s10584-011-0116-7) (2011).

Climate change impacts food production systems, particularly in locations with large, vulnerable populations. Elevated greenhouse gases (GHG), as well as land cover/land use change (LCLUC), can influence regional climate dynamics. Biophysical factors such as topography, soil type, and seasonal rainfall can strongly affect crop yields. We used a regional climate model derived from the Regional Atmospheric Modeling System (RAMS) to compare the effects of projected future GHG and future LCLUC on spatial variability of crop yields in East Africa.

NELSON, D., H. Elmer, R. HELD, D. FORSYTHE, S. CASEY, H. Stirratt, D. Bergeron, F. Lichtkoppler, J. Schomberg, and M. Dolor. Laurentian Great Lakes basin climate change adaptation. NOAA Technical Memorandum GLERL-153. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 43 pp. (2011).

The NOAA Great Lakes Regional Collaboration Team, Great Lakes Sea Grant Network, and Old Woman Creek National Estuarine Research Reserve are working with the Great Lakes & Saint Lawrence Cities Initiative to develop specialized training to build the capacity of Great Lakes coastal communities to adapt to the impacts of climate change. Training could address issues such as climate change research; long-term forecasts for climate change impacts in the Great Lakes region; processes by which community leaders can identify and consider management responses necessary to respond to forecasted changes; and decision tools and science-based resources that are available to make coastal development, resource protection, and infrastructure decisions today that sustain communities for the next 50-100 years. To ensure that training meets priority needs and provides accessible and applicable tools and resources, these organizations are collaborating to conduct a needs assessment: a comprehensive front-end evaluation of the climate change adaptation training and information needs of Great Lakes coastal communities.  The goal of this needs assessment is to collect sufficient information about the knowledge, skills, interest, attitudes, and/or abilities of Great Lakes coastal community planners, stormwater managers, and natural resource managers to design effective training that increases the ability of these groups to confront and adapt to the impacts of climate change.

O'Donnell, D.M., S.W. Effler, C.M. Strait, and G.A. LESHKEVICH. Optical characterizations and pursuit of optical closure for the western basin of Lake Erie through in situ measurements. Journal of Great Lakes Research 36:736-746 (2010).

In situ measurements of inherent (IOPs) and apparent optical properties (AOPs), along with laboratory measurements of optically active constituents, were made at sites (n=14) in western Lake Erie following a wind event to advance the characterization of the underwater and emergent light fields of these waters and to support related IOP-based model development and testing. Modern instrumentation was used to make spectral (wavelength, λ) measurements of the IOPs of absorption [a(λ)], particulate scattering [bp(λ)], and particulate backscattering [bbp(λ)] coefficients, and the AOPs of remote sensing reflectance [Rrs(λ)], and the diffuse attenuation coefficient for downwelling irradiance [Kd(λ)]. Optical closure analyses were conducted to demonstrate the credibility of the measurements, by comparing AOP observations to predictions based on radiative transfer expressions that utilized IOP measurements as inputs. Substantial spectral variations in a and its contributing components, and more modest wavelength dependencies for bp and bbp, were documented that are consistent with observations reported for marine case 2 systems. The backscattering ratio, bbp:bp, was strongly positively related to the contribution of minerogenic particles to the overall concentration of suspended particulate material. Major spatial differences in both IOPs and AOPs were observed that were driven by the attendant differences in the concentrations and composition of the optically active constituents, but particularly minerogenic particles, mediated in part by sediment resuspension. Good optical closure between the independently measured IOPs and AOPs was achieved. Direct measurement of bbp(λ) was found to be critical to pursue closure for Rrs(λ) and thereby support related remote sensing initiatives.

Pichlová-Ptácníková, R., and H.A. VANDERPLOEG. The quick and the dead: Might differences in escape rates explain the changes in the zooplankton community composition of Lake Michigan after invasion by Bythotrephes? Biological Invasions:10 pp. (DOI: 10.1007/s10530-011-0076-x) (2011).

We demonstrate that zooplankton escape abilities are consistent with the composition of the zooplankton community in the Great Lakes following the invasion of the visually preying invertebrate predator Bythotrephes longimanus. Escape abilities were analyzed by videotaping responses of freeswimming zooplankton to encounters with tethered Bythotrephes. Both maximum speed and maximum acceleration of the escape response were appreciably greater in Daphnia mendotae and diaptomids, whose populations remained relatively unchanged, than those of Daphnia retrocurva and Daphnia pulicaria, whose populations greatly decreased after the Bythotrephes invasion. Maximum speed of all species was higher in the light than in complete darkness, likely due to a different level of activity of Bythotrephes. Contrary to treatments with Bythotrephes, mean and maximum swimming speeds of all species were similar to each other and the same in light and dark in treatments without Bythotrephes. This implies that the prey were responding to infochemicals produced by Bythotrephes.

POTHOVEN, S.A., D.W. Hondorp, and T.F. NALEPA. Declines in deepwater sculpin Myoxocephalus thompsonii energy density associated with the disappearance of Diporeia spp. in lakes Huron and Michigan. Ecology of Freshwater Fish 20:14-22 (2011).

The deepwater sculpin Myoxocephalus thompsonii is a glacial relict in the Laurentian Great Lakes that primarily consumes two glacial relict crustaceans, Mysis relicta and Diporeia spp. Deepwater sculpin were collected in Lake Michigan off Little Sable Point (in 2001) and Muskegon, Michigan (in 2001 and 2009), and in Lake Huron off Harbor Beach, Michigan (in 2007) for energy density and diet analyses. These sites and years represented differences in available prey. In Lake Michigan, energy densities of deepwater sculpin in 2001 were similar to those reported in 1969–1971. In contrast, energy content declined at least 26% at Muskegon between 2001 and 2009. Overall, energy density was 31–34% higher at a site with abundant Diporeia spp. compared with two sites without Diporeia spp. Deepwater sculpin diets consisted primarily of M. relicta at all sites, but included 10–17% (dry mass) Diporeia spp. at sites where this crustacean was still abundant. Food biomass in stomachs was higher at sites with abundant Diporeia spp. than at those without Diporeia spp. Deepwater sculpin energy density and food biomass in stomachs were similar between two sites without Diporeia spp. despite differences in abundance of remaining prey, M. relicta. Declines in deepwater sculpin energy density suggest the potential for further effects on other species and changes in the flow of energy through the food web of the Great Lakes.

Read, J., V. Klump, T.H. JOHENGEN, D.J. SCHWAB, K. Paige, S. Eddy, E.J. ANDERSON, and C. Manninen. Working in freshwater: The Great Lakes Observing System contributions to regional and national observations data infrastructure, and decision support. Marine Technology Society Journal 44(6):84-98 (2010).

The Laurentian Great Lakes is the world’s largest freshwater ecosystem. A charge of the Great Lakes Observing System (GLOS) Regional Association is to help coordinate and integrate data and information relative to the needs of multiple user communities—decision makers with responsibility for coastal resources, maritime operations, human health and water security data, and issues associated with adapting to climate change and weather-related hazards. This article outlines the process GLOS has developed for determining regional data and information needs, how GLOS outreach activities inform data management functions and the development of decision support tools, and how the nearshore network of multiple observation platform types was conceived and is being implemented. The article finishes with a case study of this approach as it is being applied to source water protection, spill response, and search and rescue in the St. Clair River, Lake St. Clair, and Detroit River, the connecting channels that link Lake Huron to Lake Erie.

ROBERTS, J.J., S.B. Brandt, D.L. FANSLOW, S.A. Ludsin, S.A. POTHOVEN, D. Scavia, and T.O. Hook. Effects of hypoxia on consumption, growth, and RNA:DNA ratios of young yellow perch. Transactions of the American Fisheries Society 140:1574-1586 (DOI:10.1080/00028487.2011.638576) (2011).

As in various freshwater and coastal marine ecosystems worldwide, seasonal bottom water hypoxia is a recurring phenomenon in Lake Erie’s central basin. While bottom hypoxia can strongly affect sessile benthic animals, its effects on mobile organisms such as fish are less understood. We evaluated the potential for bottom hypoxia to affect the growth rates of yellow perch Perca flavescens, a species of ecological and economic importance in the lake. To this end, we (1) conducted laboratory experiments to quantify the effects of reduced dissolved oxygen on consumption, somatic growth, and RNA:DNA ratios (an index of short-term growth) of young yellow perch and (2) explored the effects of bottom hypoxia on young yellow perch growth in Lake Erie’s central basin by collecting individuals in hypoxic and normoxic regions of the lake and quantifying their RNA:DNA ratios. Yellow perch consumption and growth in our experiments declined under hypoxic conditions (≤2 mg O2/L). While yellow perch RNA:DNA ratios responded strongly to experimental temperature, nucleic acid ratios were not significantly affected by dissolved oxygen or feeding ration. We did, however, observe a positive correlation between yellow perch growth and RNA:DNA ratios at low temperatures (11oC). The nucleic acid ratios of yellow perch collected in Lake Erie varied spatiotemporally, but their patterns were not consistent with hypoxia. In short, while yellow perch consumption and growth rates respond directly and negatively to low oxygen conditions, these responses are not necessarily reflected in RNA:DNA ratios. Moreover, in central Lake Erie, where yellow perch can behaviorally avoid hypoxic areas, the RNA:DNA ratios of yellow perch do not respond strongly to bottom hypoxia. Thus, this study suggests that there is no strong negative effect of bottom hypoxia on the growth of young yellow perch in Lake Erie.

Stroud, J.R., M.L. Stein, B.M. Lesht, D.J. SCHWAB, and D. BELETSKY. An ensemble Kalman filter and smoother for satellite data assimilation. Journal of the American Statistical Association 105(491):976-990 (2010).

This paper proposes a methodology for combining satellite images with advection-diffusion models for interpolation and prediction of environmental processes. We propose a dynamic state-space model and an ensemble Kalman filter and smoothing algorithm for on-line and retrospective state estimation. Our approach addresses the high dimensionality, measurement bias, and nonlinearities inherent in satellite data. We apply the method to a sequence of SeaWiFS satellite images in Lake Michigan from March 1998, when a large sediment plume was observed in the images following a major storm event. Using our approach, we combine the images with a sediment transport model to produce maps of sediment concentrations and uncertainties over space and time.We show that our approach improves out-of-sample RMSE by 20%–30% relative to standard approaches. This article has supplementary material online.

Szalinska, E., K.G. Drouillard, E.J. ANDERSON, and G.D. Haffner. Factors influencing contaminant distribution in the Huron-Erie Corridor sediments. Journal of Great Lakes Research 37(1):132-139 (2011).

The study discusses the role of natural and anthropogenic factors influencing dispersal of both inorganic and organic pollutants in the sediments based on findings for different aquatic sub-systems (fluvial, deltaic, lacustrine) joined into one waterway (Huron-Erie Corridor, North America). Bottom current velocity, finest fraction (b0.063 mm), Al, Corg, TN, and oil contents have been selected as the potential factors influencing contaminant distribution, most commonly used in the geochemical studies. It was found that studied subsystems were heterogeneous not only in terms of hydrological and geochemical conditions, but also with respect to the spatial contaminants patterns. Both metals and organic contaminants revealed elevated concentrations in sites localized in proximity of anthropogenic sources. The fact that the finest fraction (b0.063 mm), Al, Corg, and TN were mostly not effective as the contaminant scavengers in the studied area brings more attention to the other than geochemical factors responsible for the distribution of contaminants in sediments. These findings demonstrate that the common approach is not always suitable in describing the contaminants dispersal patterns.

Tamburri, M.N., T.F. JOHENGEN, J.F. Atkinson, D.W.H. Schar, C.Y. Robertson, H. Purcell, G.J. Smith, A. Pichuk, and E.N. Buckley. Alliance for Coastal Technologies: Advancing moored pCO2 instruments in coastal waters. Marine Technology Society Journal 45(1):43-51 (2011).

The Alliance for Coastal Technologies (ACT) has been established to support innovation and to provide the information required to select the most appropriate tools for studying and monitoring coastal and ocean environments. ACT is a consortium of nationally prominent ocean science and technology institutions and experts who provide credible performance data of these technologies through third-party, objective testing. ACT technology verifications include laboratory and field tests over short- and long-term deployments of commercial technologies in diverse environments to provide unequivocal, unbiased confirmation that technologies meet key performance requirements. ACT demonstrations of new technologies validate the technology concept and help eliminate performance problems before operational introduction. ACT’s most recent demonstration of pCO2 sensors is an example of how ACT advances the evolution of ocean observing technologies, in this case to address the critical issue of ocean acidification, and promotes more informed decision making on technology capabilities and choices.

Yang, X.Y., J. Hu, J. WANG, and D. Wang. Linkage between winter air temperature over the subtropical western Pacific and the ice extent anomaly in the Sea of Okhotsk. Journal of Oceanography 67:12 pp. (DOI 10.1007/s10872-011-0018-3) (2011).

This study deals with the correlation between ice extent in the Sea of Okhotsk and the interannual variability of winter (December–February) air temperature over the subtropical Western Pacific from 1979 to 2008. The analysis indicates that the increase in sea ice extent coincides not only with cooling over the Sea of Okhotsk and the adjacent area, but also with significant warming over the subtropical Western Pacific that extends from the surface to the middle troposphere. This meridional dipole pattern of tropospheric temperature anomalies (cooling in the high latitudes and warming in the low latitudes) primarily results from dynamical processes driven by the large-scale atmospheric circulation change. A heat budget diagnosis reveals that when ice extent in the Sea of Okhotsk increases by one standard deviation, the tropospheric air temperature over the subtropical Western Pacific rises by about 0.25oC. It also suggests that the adiabatic heating and stationary eddy heat flux convergence may be the most important factors, which account for 30 and 15% of the warming, respectively. In addition, these two factors also coordinate to result in significant cooling over the Sea of Okhotsk and the adjacent regions.

Young, W.A., D.F. Millie, G.R. Weckman, J.S. Anderson, D.M. Klarer, and G.L. FAHNENSTIEL. Modeling net ecosystem metabolism with an artificial neural network and Bayesian belief network. Environmental Modelling and Software 26:1199-1210 (2011).

Artificial neural networks (ANNs) and Bayesian belief networks (BBNs) utilizing select environmental variables were developed and evaluated, with the intent to model net ecosystem metabolism (a proxy for system trophic state) within a freshwater wetland. Network modeling was completed independently for distinct data subsets, representing periods of ‘low’ and ‘high’ water levels throughout in the wetland. ANNs and BBNs were ‘benchmarked’ against traditional parametric analyses, with network architectures outperforming regression models. ANNs delivered the greatest predictive accuracy for NEM and did not require expert knowledge about system variables for their development. BBNs provided users with an interactive diagram depicting predictor interaction and the qualitative/quantitative effects of variable dynamics upon NEM, thereby affording better information extraction. Importantly, BBNs accommodated the imbalanced nature of the dataset and appeared less affected (than ANNs) with variable autocorrelation traits that are typically observed within large and ‘noisy’ environmental datasets.

ZHANG, H., D.A. Culver, and L. Boegman. Dreissenids in Lake Erie: An algal filter or a fertilizer? Aquatic Invasions Special Issue: Quagga Mussels in the Western United States - Monitoring and Management 6(2):174-194 (DOI:10.3391/ai.2011.6.2.07) (2011).

After successfully occupying the benthos of all the Laurentian Great Lakes and connecting channels, quagga mussels [Dreissena rostriformis bugensis (Andrusov, 1897)] have been colonizing the western United States at a much faster rate. Study findings and management experience in the Great Lakes will benefit the water resource managers in the western United States and help them be better prepared to act quickly and effectively to mitigate mussel impacts. We investigated the impacts of dreissenid mussels on nutrients and plankton using a two-dimensional Ecological model of Lake Erie (EcoLE), and compared their impacts with those of mesozooplankters. Model results showed that in the shallow western basin, mussel daily grazing impact was less than 10% of the combined Non-Diatom Edible Algae (NDEA) and diatom biomass, although they cleared a volume equivalent to 20% of the water column daily. Moreover, in the deep central and eastern basins, dreissenids grazed only 1-2% of the NDEA and diatom biomass per day. The relative importance of dreissenids’ grazing impact on diatoms and NDEA to those of zooplankton’s varied among years and basins in Lake Erie. In general, zooplankton had slightly higher grazing impacts than did the mussels on NDEA and diatoms in the western basin but much higher grazing impacts in the central basin. Dreissenid mussels excreted a big portion of phosphorus in the bottom water, especially in the western basin, while zooplankton kept a big portion of algal phosphorus in the water column, especially in the central and eastern basins. Non-Diatom Inedible Algae (NDIA) abundance increased with more phosphorus available and was less responsive to mussel selective grazing. Dreissenid mussels affected crustacean zooplankton mainly through their impacts on NDEA. Our results thus indicate that dreissenid mussels have weak direct grazing impacts on algal biomass due to a concentration boundary layer above the mussel bed, while their indirect effects through nutrient excretion have much greater and profound negative impacts on the system. EcoLE is a modification of CEQUAL-W2, which is frequently applied to western aquatic systems, and we suggest that with this modification, the models can be used to predict dreissenid impacts in western lakes, reservoirs, and rivers in which they may become established.

Zhao, S., P. Zhang, J. Crusius, K.D. Kroeger, and J.F. BRATTON. Use of pharmaceuticals and pesticides to constrain nutrient sources in coastal groundwater of northwestern Long Island, New York, USA. Journal of Environmental Monitoring 13:1337-1343 (DOI:10.1039/C1EM10039D) (2011).

In developed, non-agricultural, unsewered areas, septic systems and fertilizer application to lawns and gardens represent two major sources of nitrogen to coastal groundwater, in addition to atmospheric input. This study was designed to distinguish between these two possible nitrogen sources by analyzing groundwater samples for pharmaceutical residuals, because fertilizers do not contain any of these pharmaceuticals, but domestic wastewater commonly does. In addition, several herbicides and insecticides used in lawn treatment were analyzed as indicators of nitrogen delivery to groundwater from fertilizers. Groundwater samples were taken through piezometres at shoreline sites in unsewered areas surrounding Northport Harbor and in sewered areas adjacent to Manhasset Bay (hereafter referred to as “Northport” and “Manhasset”, respectively), both in northwestern Long Island, USA. Excessive nitrogen loading has led to reduced dissolved oxygen concentrations in Long Island Sound, and the groundwater contribution to the nitrogen budget is poorly constrained. The frequent detection of the anticonvulsant compound carbamazepine in groundwater samples of the Northport Harbor area (unsewered), together with the fact that few pesticides associated with lawn applications were detected, suggests that wastewater input and atmospheric input are the likely sources of nitrogen in the Northport groundwater. High concentrations of nitrogen were also detected in the Manhasset (sewered) groundwater. The low detection frequency and concentration of carbamazepine, however, suggest that the sewer system effectively intercepts nitrogen from wastewater there. The likely sources of nitrogen in the Manhasset groundwater are atmospheric deposition and lawn fertilizers, as this area is densely populated.


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