GLERL Publication Abstracts: FY 2009


Basu, N., J.A. HEAD, A.M. Scheuhammer, S.J. Bursian, K. Rouvinen-Watt, and H.M. Chan. The mink is still a reliable sentinel species in environmental health. Environmental Research 109:940-941 (2009). 20090033DNP.pdf

We thank Bowman and Schulte-Hostedde(2009) for their useful commentary. As outlined in our paper, mink have several characteristics that support their value as a sentinel species (Basu et al., 2007). Key characteristics of a sentinel species in the field of environmental health are provided in Table 1 of our paper and these were adapted from extensive reviews conducted by academic scientists and government panels (Beeby, 2001; Fox, 2001; LeBlanc and Bain,1997; National Research Council,1991; Van derSchalie et al., 1999). As there are few mammalian species that can effectively meet such criteria (Golden and Rattner, 2003), it is no surprise that mink have been recognized as an excellent sentinel by many agencies worldwide. The main assertion by Bowman and Schulte-Hostedde (2009) is that because of the high frequency of ranch escapees, mink are not‘‘ a continuous resident of the environment under evaluation’’ (criteria adapted from a ‘‘critique’’  paper written by Landres et al.,1988), and that this precludes their value as sentinel species. While we agree that the presence of ranched mink in the wild population is a confounding factor for some ecotoxicological studies and should be taken into account when designing environmental research or monitoring studies using mink, we disagree with the conclusion that ‘‘the mink is not a  reliable sentinel species’’.

BELETSKY, D., and D.J. SCHWAB. Climatological circulation in Lake Michigan. Geophysical Research Letters 35(L21604):5 pp. (DOI:10.1029/2008GL035773) (2008). 20080058DNP.pdf

Maps of climatological circulation in Lake Michigan are presented for the first time. They are based on ten years continuous modeling of lake hydrodynamics from 1998–2007 using observed meteorological data as the forcing function. Model results show a remarkably stable largescale cyclonic circulation pattern during both stratified and unstratified conditions. Lake-averaged mean current speed is about 2 cm/s, but currents can reach 10 cm/s in some locations. The model results are confirmed by long-term current observations.

Biddanda, B.A., S.C. Nold, S.A. RUBERG, S.T. Kendall, T.G. Sanders, and J.J. Gray. Great Lakes sinkholes: A microbiogeochemical frontier. EOS Transactions 90(8):61-62 (2009). 20090010DNP.pdf

Recent underwater explorations have revealed unique hot spots of biogeochemical activity at several submerged groundwater vents in Lake Huron, the third largest of the Laurentian Great Lakes. Fueled by venting groundwater containing high sulfate and low dissolved oxygen, these underwater ecosystems are characterized by sharp physical and chemical gradients and spectacularly colorful benthic mats that overlie carbon-rich sediments. Here, typical lake inhabitants such as fish and phytoplankton are replaced by communities dominated by microorganisms: bacteria and archaea that perform unique ecosystem functions. Shallow, sunlit sinkholes are dominated by photosynthetic microorganisms and processes, while food webs in deep aphotic sinkholes are supported primarily by chemosynthesis.

Chang, P.A., W. Wilson, J. Carneal, P. Atsavapranee, S. Verosto, D.F. REID, and P.T. Jenkins. Final Report: Computational modeling of ballast water tanks to improve understanding and maximize effectiveness of management practices and treatment mechanisms. Phase II: Extension of Laboratory Study. NOAA Technical Memorandum GLERL-148. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 78 pp. (2009).

Mid-ocean ballast water exchange (BWE) is presently the primary management practice with widespread acceptance for reducing or preventing the spread of nonindigenous aquatic species via ballast water. Attempts to determine the efficiency of BWE via on-board experiments have generally produced inconsistent and unreliable results. Such experiments are labor intensive and difficult to run, so reproducibility is difficult to demonstrate for the same ship and tank structure. In addition, on-board experiments involving flow-through exchange generally relied on measurements taken at the overflow outlet of the tank, which may not represent the actual volume mixture that remains in the ballast tank. Given the complex structural nature of ballast tanks and the difficulty of obtaining direct experimental verification from inside ballast tanks, development of a computer-based model of the flow and mixing dynamics in ballast tanks during flow-through exchange can provide several advantages over on-board experimental approaches, and can also help interpret such experimental results. The NOAA Ballast Water Technology Demonstration Program provided funding for GLERL and NSWCCD to design and build a 1/3-scale model BWE facility and to develop a computational model for predicting BWE efficacy. In Phase I of this effort, documented in Wilson et al. a 1/3-scale physical model facility was built at NSWCCD. In this report the (physical) scale-model experimental setup and measurement techniques used in Phases I and II of this project are described. Then, the results and the two-fluid physics that were observed during the entire 3-TVE are shown. In the CFD section the methodology is described followed by comparisons of the CFD predictions with the measured quantities from the physical scale-model experiments. Additionally, full-scale simulations are documented and an Appendix shows the uncertainty analysis.

Chatterjee, A., C. DeMARCHI, and A.M. Michalak. Estimating over-lake precipitation in the Great Lakes by combining radar and rain gages. Seventh International Symposium on Ecohydraulics and Eighth International Conference on Hydroinformatics, Concepcion, Chile, January 12-16, 2009, 10 pp. (2009).

Over-lake precipitation is a key component of the Great Lakes’ water balance. Its estimation is, therefore, vital for planning and operational purposes. Yet, reliable over-lake precipitation estimates are difficult to obtain because the lack of gages on the lakes themselves and the scarcity of gages in parts of the draining basins. Traditionally, over-lake precipitation is estimated by distance-weighted interpolation methods. In spite of their wide acceptance, these methods suffer from intrinsic limitations as they fail to take into account the spatial variability of rainfall. Recently, multisensor products combining radar-based precipitation estimates and rain gage data (MPE) have provided a suitable alternative to estimates based on the sparse gage data. However, biases in the MPE data have raised serious concerns about their accuracy. A promising approach for overcoming the limitations of either of these methodologies for estimating monthly-averaged over-lake precipitation is to spatially integrate the MPE data with the gage observations in a geostatistical framework based on universal kriging. In this work, the estimates from these techniques are compared to (i) more traditional methods based on the weighted interpolation gage data only, and (ii) the available MPE data. Results for Lake Erie reveal that the universal kriging setup outperforms the estimation methods based only on one of the two data types, by providing estimates with significantly lower root mean square error and lower overall bias. Overall, the results demonstrate the robustness of the proposed approach in assimilating two different information sources for providing more accurate and reliable estimates of over-lake precipitation.

DeMARCHI, C., T.E. CROLEY II, T.S. HUNTER, and C. He. Application of a distributed watershed hydrology and water quality model in the Great Lakes basin. Seventh International Symposium on Ecohydraulics and Eighth International Conference on Hydroinformatics, Concepcion, Chile, January 12-16, 2009, 10 pp. (2009).

The NOAA Great Lakes Environmental Research Laboratory, Western Michigan University, and the University of Michigan are jointly developing a Distributed Large Basin Runoff Model (DLBRM), a physically based, spatially-distributed hydrology and water quality model, to simulate spatial and temporal point and nonpoint source material distributions in Great Lakes watersheds. We automatically calibrated the DLBRM hydrology to reproduce the 1950-1964 and the 1999-2006 watershed outflows in 18 watersheds throughout the Great Lakes region with excellent results; we are extending it to an additional 16 watersheds. In this paper, we analyze the performance of the DLBRM hydrology components in space and time and its further development.

Dettmers, J.M., C.P. Madenjian, P.J. Allen, S.A. POTHOVEN, and T.F. NALEPA. Impacts of recent invasive species on nearshore fishes. In The State of Lake Michigan in 2005. D.F. Clapp and W. Horns (eds.). Great Lakes Fishery Commission Special Publication 08-02. Great Lakes Fishery Commission, Ann Arbor, MI, pp. 19-26 pp. (2008).

Invasive species have impacted Lake Michigan’s fisheries for 70 years. The passage through the Welland Canal by sea lamprey, after it invaded Lake Ontario, led to its establishment in Lake Michigan where it was first seen in 1936 (Christie and Goddard 2003). A combination of overfishing and sea lamprey predation led to the extirpation of lake trout (Coble et al. 1990; Hansen 1999) and to the extirpation or extinction of several deepwater ciscoes endemic to the Great Lakes (Coon 1999). Alewives, probably through interference with reproduction, likely caused the decline in abundances of deepwater sculpins and yellow perch during the 1960s and may have delayed the recovery of burbot in Lake Michigan until the 1980s (Madenjian et al. 2002). From 1959 to 1999, the rate of new introductions into the Great Lakes has increased to more than one species per year (Grigorovich et al. 2003), resulting in the establishment of numerous invaders during the past 20 years. In this report, we focus on (1) the status of six recent invasive species during 2000-2004, (2) the identity of other species that could invade in the near future, (3) examples of their impacts on the nearshore fish community, and (4) the implications for fishery management.

Dufour, E., T.O. HÖÖK, W.P. Patterson, and E.S. RUTHERFORD. High resolution isotope analysis of young alewife Alosa pseudoharengus otoliths: assessment of temporal resolution and reconstruction of habitat occupancy and thermal history. Journal of Fish Biology 73:2434-2451 (2008).

Otoliths of age 0 year alewife Alosa pseudoharengus collected in different Lake Michigan habitats were microsampled, and carbon and oxygen isotope ratios (δ18Ootolith and δ13Cotolith) of resulting microsamples were quantified. To assess the temporal resolution of the method, age and otolith growth rates were also estimated by counting otolith daily growth increments. Core and outer intra-otolith samples averaged 36 and 23 days, respectively. Because of the accretionary nature of otolith growth, a habitat switch by a larva occurring between 0 and 18 days post-hatch may not be recognized by this approach. Taking this temporal resolution into account, A. pseudoharengus habitat occupancy and thermal history in nearshore Lake Michigan, and a connecting drowned river-mouth lake were documented. Comparisons between δ18Ootolith and δ13Cotolith profiles, and isotope values of Lake Michigan habitats suggested that movements by individual fish between a nearshore area of Lake Michigan proper and drowned river-mouth lake habitats were rare. Some individuals evidently moved between habitats, and such movements occurred during different periods of ontogeny. Thermal reconstructions, based on δ18Ootolith values suggested that during early life (e.g. first month of life) young A. pseudoharengus appeared to inhabit microhabitats with temperatures greater than mean epilimnetic temperatures. This study demonstrates not only the utility of intra-otolith geochemical analysis to describe the complexity of fish behaviour in fresh water but also identifies limitations of the present approach.

EADIE, B.J., J.A. ROBBINS, J. Val Klump, D.J. SCHWAB, and D.N. Edgington. Winter-spring storms and their influence on sediment resuspension, transport, and accumulation patterns in southern Lake Michigan. Oceanography 21(4):118-135 (2008).

The Episodic Events-Great Lakes Experiment was designed to quantify the impacts of major late winter-early spring storms on sediment-water exchange, sediment, and associated constituent transport and resultant influence on well-characterized sediment distributions in southern Lake Michigan. Prior to this project, only very sparse data were available during the late winter-early spring period for any of the Great Lakes, primarily because of strong storms and ice conditions. The observation strategy consisted of moored arrays of current meters, thermistors, and sequencing traps, along with shipboard surveys. In addition, process measurement cruises were conducted along with special cruises for sedimentwater interface sampling using a remotely operated vehicle, particle transformation measurements, and sediment collection. A summary of conclusions include: (1) particles, predominantly from the western shore of the lake, are resuspended and transported in a coastal band toward the major sediment depositional region in the southeastern portion of the lake, (2) transport rates, measured by 234Th, are on the order of kilometers per day, (3) the magnitude of resuspended sediments from a single major storm is 1–5 x 106 kg, larger than annual external input of fine-grained materials to the southern basin, (4) resuspension surrogates based on 50 years of wave data show an interannual variability in major storm events that ranges over an order of magnitude, and (5) trap and 7Be evidence indicates that the events appear to be primarily responsible for the complicated sediment accumulation patterns in the southern basin of Lake Michigan.

FAHNENSTIEL, G.L., Y. Hong, D.F. Millie, M. Doblin, T.F. JOHENGEN, and D.F. REID. Marine dinoflagellate cysts in the ballast tank sediments of ships entering the Laurentian Great Lakes. Verh. Internat. Verein. Limnol. 30(7):1035-1038 (2009).

One of the greatest threats to the ecological health of the Laurentian Great Lakes is the introduction of non-indigenous species (Mills et al. 1993). The Laurentian Great Lakes have a long history of non-indigenous introductions with significant ecological and economic consequences. Since the opening of the St. Lawrence Seaway in 1959, approximately 65% of all non-indigenous species introductions into the Great Lakes have been attributed to ballast water release (Ricciardi 2006). Because of the concern of ballast water and its potential for introduction of non-indigenous species, the U.S. Coast Guard promulgated regulations in 1993, requiring ships with ballast water inbound to the Great Lakes to exchange ballast water with open ocean water. Despite these new regulations, the discovery rate of non-indigenous species increased after mandatory controls were implemented (Holek et al. 2004). Unfortunately, most of the ships entering the Great Lakes are exempt from the 1993 regulations. The majority of ships entering the Great Lakes since 1993 are loaded with cargo and are declared as ‘no ballast water on board’ (NOBOB) ships. These NOBOB ships carry residual water and sediments in their ballast tanks. Once in the Great Lakes these NOBOB ships discharge their residual water and sediment into the Great Lakes during the off-loading of inbound cargo and the loading of outbound cargo. These NOBOB ships represent a greater risk for introductions into the Great Lakes than ballasted ships (Duggan et al. 2005).

FAHNENSTIEL, G.L., M.J. McCORMICK, and R. Artz. Proceedings of NOAA Lake Champlain Program Review - October 29-30, 2008. NOAA Technical Memorandum GLERL-146. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 50 pp. (2009).

On October 29-30 2008, a formal review of NOAA’s Lake Champlain Research Program was held in Burlington, Vermont. Despite being in existence for 18 years, this was the first external review of the program. The first day of the review consisted of project presentations and open discussions of existing research and future directions (see Appendix 1). Principal investigators from all four funded projects were asked to make formal presentations as well as provide a summary (1-2 pages with supplementary materials as needed). The summaries and supplementary materials were made available to the public (see Appendix 2). Five external experts (two in hydrodynamics research, two in atmospheric/mercury research, and one oceanographer/ecologist) were invited to review the research activities with special attention to the quality and quantity of existing research and future direction. The first day of the review was open to the public, approximately 35 people attended. On the second day, NOAA program managers met with the review panel to discuss the program in a closed session. This technical report summarizes the review meeting.

Freeman, A.M., E.C. Lamon, and C.A. STOW. Nutrient criteria for lakes, ponds, and reservoirs: A Bayesian TREED model approach. Ecological Modelling 220:630-639 (2009). 20090006.pdf

We develop regional-scale eutrophication models for lakes, ponds, and reservoirs to investigate the link between nutrients and chlorophyll-a. The Bayesian TREED (BTREED) model approach allows association of multiple environmental stressors with biological responses, and quantification of uncertainty sources in the empirical water quality model. Nutrient data for lakes, ponds, and reservoirs across the United States were obtained from the Environmental Protection Agency (EPA) National Nutrient Criteria Database. The nutrient data consist of measurements for both stressor variables (such as total nitrogen and total phosphorus), and response variables (such as chlorophyll-a), used in the BTREED model. Markov chain Monte Carlo (McMC) posterior exploration guides a stochastic search through a rich suite of candidate trees toward models that better fit the data. The Bayes factor provides a goodness of fit criterion for comparison of resultant models. We randomly split the data into training and test sets; the training data were used in model estimation, and the test data were used to evaluate out-of-sample predictive performance of the model. An average relative efficiency of 1.02 between the training and test data for the four highest log-likelihood models suggests good out-of-sample predictive performance. Reduced model uncertainty relative to over-parameterized alternative models makes the BTREED models useful for nutrient criteria development, providing the link between nutrient stressors and meaningful eutrophication response.

HAWLEY, N. A digital data base for the particle size distribution of bottom sediments in Lake Michigan. NOAA Technical Memorandum GLERL-145. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 17 pp. (2008).

This document describes a map of the size distribution of bottom sediments in Lake Michigan. The data set combines measurements of the bottom sediment size distribution made by several previous investigations. The results are presented on the same 2 km grid presently used for forecasting waves and currents in the lake.

He, C., and C. DeMARCHI. Modeling spatial distributions of point and nonpoint source pollution loadings in the Great Lakes watersheds. World Academy of Science, Engineering, and Technology 54:795-801 (2009).

A physically based, spatially-distributed water quality model is being developed to simulate spatial and temporal distributions of material transport in the Great Lakes Watersheds of the U.S. Multiple databases of meteorology, land use, topography, hydrography, soils, agricultural statistics, and water quality 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 estimates by crop for the same periods. Comparison of these estimates to the monitored total phosphorous load indicates that both point and nonpoint sources are major contributors to the total nutrient loads in the study watersheds, with nonpoint sources being the largest contributor, particularly in the rural watersheds. These estimates are used as the input to the distributed water quality model for simulating pollutant transport through surface and subsurface processes to Great Lakes waters. Visualization and GIS interfaces are developed to visualize the spatial and temporal distribution of the pollutant transport in support of water management programs.

He, C., and C. DeMARCHI. Modeling spatial distributions of point and nonpoint source pollution loadings in the Great Lakes watersheds. International Journal of Environmental Science and Engineering 2(1):24-30 (2010).

A physically based, spatially-distributed water quality model is being developed to simulate spatial and temporal distributions of material transport in the Great Lakes Watersheds of the U.S. Multiple databases of meteorology, land use, topography, hydrography, soils, agricultural statistics, and water quality 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 estimates by crop for the same periods. Comparison of these estimates to the monitored total phosphorous load indicates that both point and nonpoint sources are major contributors to the total nutrient loads in the study watersheds, with nonpoint sources being the largest contributor, particularly in the rural watersheds. These estimates are used as the input to the distributed water quality model for simulating pollutant transport through surface and subsurface processes to Great Lakes waters. Visualization and GIS interfaces are developed to visualize the spatial and temporal distribution of the pollutant transport in support of water management programs.

He, C., C. DeMARCHI, T.E. CROLEY II, Q. Feng, and T.S. HUNTER. Hydrologic modeling of the Heihe wateshed by DLBRM in Northwest China. Journal of Glaciology and Geocryology 31(3):411-421 (2009).

Water shortage is a chronic problem in arid Northwest China. The increasing poulation growth and expanding urbanization as well as potential climate change impacts are likely to worsen the situation, threatening domestic, irrigation, and industrial supplies and even the survivial of the ecosystems in Northwest China. This paper describes the preliminary work of adapting the Distributed Large Basin Runoff Model (DLBRM) to the Heihe watershed (the second largest inland river in arid Northwestern China, with a drainage area of 128,000 km2) for understanding distribution of 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. Preliminary simulation results show that Qilian Mountain in the upper reach area produces most runoff in the Heihe watershed. The simulated daily river flows of the 1990-2000 indicate that the Heihe River discharges about 1 billion m3 of water from the middle reach (at Zhengyixia station) to lower reach, with surface runoff and interflow contributing 51 and 49 percent respectively. The sandy lower soil zone in the middle reach has the highest evapotranspiration rate and also contributed nearly half of the river flow. Work underway focuses on the DLBRM model improvement and incorporation of the climate chanage and management scnarios to the hydrological simualtions in the watershed.

HÖÖK, T.O., and S.A. POTHOVEN. Energy content of young alewives in eastern Lake Michigan and Muskegon Lake, a connected drowned river mouth lake. North American Journal of Fisheries Management 29(2):378-387 (2009).

Energy content is an important determinant of an individual fish’s condition and a key input variable for bioenergetics applications. Energy content of young fish can change rapidly during ontogeny; given the numerical abundance and high mass-specific metabolic rates of young fish, it is particularly important to obtain detailed information on their energy content. To this end, we quantified the total body energy content and energy density of economically and ecologically important young (age-0–1) nonnative alewives Alosa pseudoharengus collected during 1998–2003 in eastern Lake Michigan and Muskegon Lake, a connected drowned river mouth lake. Our analysis demonstrates that energy content of young alewives varies across years, seasons, lakes, and ontogeny. Consistent with previous observations of size-dependent overwinter mortality, young alewives deplete a large amount of body energy between late fall and late spring (i.e., declines in length-specific energy content and energy density occur overwinter). Interestingly, unlike several past studies of young fish in their native range, size-specific energy content of young alewives does not appear to increase over the summer and fall (there is no evidence of increased energy storage in preparation for the resource-scarce winter period). Finally, our measured values are similar to the few previously published energy density values for age-0 alewives. The high degree of variation in the energy content of young fish emphasizes the necessity of using appropriate energy measures for bioenergetics applications to inform fisheries management.

HU, H., and J. WANG. Modeling the ocean circulation in the Bering Sea. Chinese Journal of Polar Research 19(2):193-211 (2008).

With parameterized wave mixing, the circulation and the tidal current in the Bering Sea were simulated simultaneously using the three-dimensional Princeton Ocean Model. The simulated circulation pattern in the deep basin is relatively stable, cyclonic, and has little seasonal change. The Bering Slope Current between 200-1000 m isobaths was estimated to be 5 Sv in volume transport. The Kamchatka Current was estimated to be 20 Sv off the Kamchatka Peninsula. The Bering shelf circulations vary with season, driven mainly by wind. These features are consistent with historical estimates. A counter current was captured Howing southeastward approximately along the 200 m isobath of the Bering Slope, opposite to the northwestward Bering Slope Current, which needs to be validated by observations. An upwelling current is located in the shelf break (120-1000 m) area, which may imply the vertical advection of nutrients for supporting the Bering Sea Green Belt seasonal plankton blooms in the breakslope area. The Bering Slope Current is located in a downwelling area.

Jin, M., C. Deal, and J. WANG. A coupled ice-ocean ecosystem model for 1-D and 3-D applications in the Bering and Chukchi Seas. Chinese Journal of Polar Science 19(2):218-229 (2008).

Primary production in the Bering and Chukchi Seas is strongly influenced by the annual cycle of sea ice. Here pelagic and sea ice algal ecosystems coexist and interact with each other. Ecosystem modeling of sea ice associated phytoplankton blooms has been understudied compared to open water ecosystem model applications. This study introduces a general coupled ice-ocean ecosystem model with equations and parameters for 1-0 and 3-D applications that is based on 1-0 coupled ice-ocean ecosystem model development in the landfast ice in the Chukchi Sea and marginal ice zone of Bering Sea. The biological model includes both pelagic and sea ice algal habitats with 10 compartments: three phytoplankton (pelagic diatom, flagellates and ice algae: D, F, and Ai) , three zooplankton (copepods, large zooplankton, and microzooplankton: ZS, ZL, ZP). three nutrients (nitrate + nitrite, ammonium, silicon: N03, NH4 , Si) and detritus ( Det). The coupling of the biological models with physical ocean models is straightforward with just the addition of the advection and diffusion terms to the ecosystem model. The coupling with a multi-category sea ice model requires the same calculation of the sea ice ecosystem model in each ice thickness category and the redistribution between categories caused by both dynamic and thennodynamic forcing as in the physical model. Phytoplankton and ice algal self-shading effect is the sole feedback from the ecosystem model to the physical model.

Jin, M., C. Deal, J. WANG, and C.P. McRoy. Response of lower trophic level production to long-term climate change in the southeastern Bering Sea. Journal of Geophysical Research 114(C04010):10 pp. (DOI:10.1029/2008JC005105) (2009). 20090019DNP.pdf

[1] The Bering Sea ecosystem has undergone profound changes in response to climate regime shifts in the past decades. Here, lower trophic level production is assessed with a vertically one-dimensional (1-D) coupled ice-ocean ecosystem model, which was applied to data collected by a National Oceanic and Atmospheric Administration (NOAA)/Pacific Marine Environmental Laboratory (PMEL) mooring from 1995 to 2005. The physical model is forced by sea surface winds, heat and salt fluxes, tides, and sea ice. The biological model includes coupled pelagic and ice algae components. Model results are validated with daily mooring temperature, fluorometer, and daily Sea-viewing Wide Field-of-view Sensor (SeaWiFS) chlorophyll data. Two distinct ocean conditions and phytoplankton bloom patterns are related to the Pacific Decadal Oscillation (PDO) Index regimes: warmer temperature and later warm-water phytoplankton species bloom in PDO > 1 year; colder temperature and earlier cold-water phytoplankton species bloom in PDO < - 1 year. Productivity of different phytoplankton species changed dramatically after the 1976 climate shift, but the total annual net primary production (NPP) remained flat over the past four decades under similar nutrient regulation. Climate shift also affected the vertical distribution of lower trophic level production and energy flow to the upper ocean pelagic ecosystem or the benthic community. A long-term PDO regime shift occurred in 1976, and a short-term PDO reversal occurred in 1998. Phytoplankton biomass responded promptly to both short- and long-term climate changes. Zooplankton biomass responded more to the long-term than to the short-term climate shift. The model results captured observed trends of zooplankton abundance changes from the 1990s to 2004.

Jonas, J., R.M. Claramunt, and E.S. RUTHERFORD. Salmonine reproduction and recruitment. In The State of Lake Michigan in 2005. D.F. Clapp and W. Horns (eds.). Great Lakes Fishery Commission Special Publication 08-02. Great Lakes Fishery Commission, Ann Arbor, MI, pp. 65-70 pp. (2008).

Fostering self-sustainability and protecting the genetic diversity of fish stocks are key features of the goals and guiding rinciples in the fish community objectives for Lake Michigan (Eshenroder et al. 1995). Reliance on natural feedbacks between predator and prey to control recruitment can provide more-effective self-regulation, leading to greater system resilience and stability, than external actions, such as stocking or harvest, which entail time lags (Christie et al. 1987). The genetic fitness of self-sustaining populations likely exceeds that of stocked populations (Berejikian et al. 1999, 2001; Kostow et al. 2003), because self-sustaining populations benefit from natural selection and are able to adapt to unique and specific conditions in localized environments (Falkner and Falkner 2000). Natural recruitment of Lake Michigan salmonine populations has been quantified historically by mark-and-recapture studies of hatchery-released fish, by counting out-migrating wild smolts in tributary streams, and, more recently, by surveys of lake trout eggs and fry on spawning reefs. Because hydrologically stable, groundwater-fed streams most conducive to natural reproduction of anadromous salmonids (Carl 1983; Seelbach 1985) are generally found in just the northern and eastern areas of the lake’s basin, measures of smolt out-migration or of returning adults in streams can be difficult to translate into the whole-lake population, which also comprises stocked fish. In contrast, if recruitment of wild fish is quantified through recreational fisheries and independent assessments in the open lake, information regarding stream-specific influences on the lakewide population is not obtained. Given limited monitoring efforts, the recruitment dynamics of salmonines continues to be incompletely understood. Here we report on natural recruitment of four of the lake’s major salmonines: coho salmon, Chinook salmon, steelhead, and lake trout. We do not report on brown trout because, although it is a major salmonine, its level of natural reproduction is minimal (Keller et al. 1990).

JOSEPH, S.T., L.A. CHAIMOWITZ, M.A. QUIGLEY, R.A. STURTEVANT, D.M. MASON, C.E. SELLINGER, J. WANG, C. DeMARCHI, and S.B. BRANDT. Impact of climate change on the Great Lakes ecosystem: A NOAA science needs assessment workshop to meet emerging challenges - summary report. NOAA Technical Memorandum GLERL-147. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, Ann Arbor, MI, 48 pp. (2009).

From July 29 to 31, 2008, NOAA’s Great Lakes Environmental Research Laboratory (GLERL) co-hosted the workshop – Impact of Climate Change on the Great Lakes Ecosystem – A NOAA Science Needs Assessment to Meet Emerging Challenges. The workshop was held at the School of Natural Resources and Environment, University of Michigan Central Campus, Ann Arbor, Michigan. Workshop co-hosts were the Cooperative Institute for Limnology and Ecosystems Research (CILER), the Great Lakes Sea Grant Network, and the NOAA Great Lakes Regional Team. Event co-sponsors included: GLERL, CILER, and the Pennsylvania, Ohio, Wisconsin, Illinois/Indiana, Minnesota, and Michigan Sea Grant Programs. The purpose of the workshop was to take the first step in developing a NOAA research strategy that addresses the impact of climate change on Great Lakes coastal ecosystems that is driven by user needs. The workshop was unique because of its focus on identifying and prioritizing research needs and future plans toward understanding the impact of climate change on the physical, chemical, and biological processes in Great Lakes coastal waters and connecting channels. Previous workshops, conferences, and reports that address climate change impacts in the Great Lake region are listed in Appendix I.

Kapo, K.E., G.A. BURTON, D. de Zwart, L. Posthuma, and S.D. Dyer. Quantitative lines of evidence for screening-level diagnostic assessment of regional fish community impacts: A comparison of spatial database evaluation methods. Environmental Science and Technology 42(24):9412-9418 (2008). 20080054DNP.pdf

Determination of local ecological impacts and stressor identification in aquatic ecosystems is increasingly needed and required for designing effective watershed management plans in various jurisdictions. Spatial database evaluation methods applied to available environmental data resources can provide screening-level, geographically based stressor identification hypotheses. Cross-comparison of the output of independent methods is a critical step to address common concerns with the interpretation of output, identify strengths and weaknesses, and reduce uncertainty. Two current approaches were compared in this study: (1) the “Effect and Probable Cause” (EPC) method and (2) a GIS “Weights-of-Evidence/Weighted Logistic Regression” (WOE/WLR) method. The methods were applied to the same Ohio (U.S.) spatial data resources to link impacts on local fish assemblages with various natural and anthropogenic stressors. The methods generally yielded significantly similar results in the identification of stressors and their relative influence. However, key differences were also observed between the methods which reflected the distinctive objectives and sensitivities of each. The findings show that scientific interpretation of analysis output requires an understanding of method characteristics, and suggests the potential value of utilizing multiple methods as quantitative lines of evidence in screening-level regional diagnostic assessment.

Kidwell, D.M., A.J. Lewitus, E.B. Jewett, S.B. Brandt, and D.M. MASON. Ecological impacts of hypoxia on living resources. Journal of Experimental Marine Biology and Ecology 381:51-53 (2009). 20090039DNP.pdf

Hypoxia (typically defined as dissolved oxygen levels <2mgL−1) is a common symptom of degraded water quality that often results from anthropogenic activities (e.g., nutrient pollution). Recognized as a threat to ecosystems worldwide, the occurrence of hypoxia in coastal waters has increased steadily over the past 50 years (Diaz and Rosenberg, 2008). The formation of hypoxia is typically the result of interactions among water column stratification, biologic processes, nutrient inputs, and other factors (e.g., Rabalais et al., 2007). Although hypoxia is an inherent feature in many ecosystems, increased anthropogenic nutrient inputs and other environmental perturbations have increased both the frequency of occurrence and intensity of naturally occurring hypoxia and has induced its occurrence in ecosystems where it had not been previously documented (Hagy et al., 2004; Rabalais et al., 2007; Diaz and Rosenberg, 2008). In the United States, hypoxia has been found in over 300 ecosystems (see Diaz and Rosenberg, 2008) and often forms seasonally. Although the primary factors causing hypoxia are fundamentally understood in many ecosystems, the impacts of hypoxia on living resources and food webs are far less known.

Kiziewicz, B., and T.F. NALEPA. Some fungi and water molds in waters of Lake Michigan with emphasis on those associated with the benthic amphipod Diporeia spp. Journal of Great  Lakes Research 34:774-780 (2008).

To determine types of fungi in the water and associated with the benthic amphipod Diporeia spp., samples were collected at various depths in Lake Michigan in an area where the Diporeia population was in a severe state of decline. No fungi were found associated with living, freshly-dead, or dried Diporeia cultured separately from Lake Michigan water. When dead Diporeia and other organic substrates (snake skin and hemp seeds) were used to grow fungi in Lake Michigan water, a rich and diverse fungal and water mold community was revealed. A total of 31 species were found, with the most common genera being Achlya, Aphanomyces, Myzocytium, and Pythium. In general, species were homogeneously distributed in the water; that is, few differences were found in species richness between nearshore (10–15 m) and offshore (60–80 m) waters, and between near-surface (1 m) and near-bottom waters (1 m off bottom). Sampling occurred during the unstratified period (April and October) to maximize the number of species collected, which may have contributed to the uniform spatial pattern observed. While conclusions must be placed in context with our methods of detection, we found no evidence that a fungal infestation was associated with Diporeia in this region of the lake.

Lekki, J., R. Anderson, Q.V. Nguyen, J. Demers, G.A. LESHKEVICH, J. Flatico, and J. Kojima. Development of hyperspectral remote sensing capability for the early detection and monitoring of Harmful Algal Blooms (HABs) in the Great Lakes. AIAA Infotech Aerospace Conference, Seattle, WA, April 6-9, 2009. American Institute of Aeronautics and Astronautics, 14 pp. (2009).

Hyperspectral imagers have significant capability for detecting and classifying waterborne constituents. One particularly appropriate application of such instruments in the Great Lakes is to detect and monitor the development of potentially Harmful Algal Blooms (HABs). Two generations of small hyperspectral imagers have been built and tested for aircraft based monitoring of harmful algal blooms. In this paper a discussion of the two instruments as well as field studies conducted using these instruments will be presented. During the second field study, in situ reflectance data was obtained from the Research Vessel Lake Guardian in conjunction with reflectance data obtained with the hyperspectral imager from overflights of the same locations. A comparison of these two data sets shows that the airborne hyperspectral imager closely matches measurements obtained from instruments on the lake surface and thus positively supports its utilization for detecting and monitoring HABs.

LESHKEVICH, G.A., and S.V. Nghiem. Using satellite radar data to map and monitor variations in Great Lakes ice cover. 2009 IEEE Radar Conference, Pasadena, CA, May 4-8, 2009. IEEE, 3 pp. (2009).

Satellite-borne radars, including synthetic aperture radar (SAR) and scatterometer data, are used to classify and map Great Lakes ice cover and to derive freeze-up date, breakup date, and ice cover duration. These are important indicators of regional climatic conditions.

Lewis, C.F.M., J.W. King, S.M. Blasco, G.R. Brooks, J.P. Coakley, T.E. CROLEY, D.L. Dettman, T.W.D. Edwards, C.W. Heil, J.B. Hubeny, K.R. Laird, J.H. McAndrews, F.M.G. McCarthy, B.E. Mediolo, T.C. Moore, D.K. Rea, and A.J. Smith. Dry climate disconnected the Laurentian Great Lakes. EOS Transactions 89(52):541-542 (2008). 20080051DNP.pdf

Recent studies have produced a new understanding of the hydrological history of North America’s Great Lakes, showing that water levels fell several meters below lake basin outlets during an early postglacial dry climate in the Holocene (younger than 10,000 radiocarbon years, or about 11,500 calibrated or calendar years before present (B.P.)). Water levels in the Huron basin, for example, fell more than 20 meters below the basin overflow outlet between about 7900 and 7500 radiocarbon (about 8770–8290 calibrated) years B.P. Outlet rivers, including the Niagara River, presently falling 99 meters from Lake Erie to Lake Ontario (and hence Niagara Falls), ran dry. This newly recognized phase of low lake levels in a dry climate provides a case study for evaluating the sensitivity of the Great Lakes to current and future climate change.

LIU, P.C., H.S. Chen, D.J. Doong, C.C. Kao, and Y.J.G. Hsu. Freaque waves during Typhoon Krosa. Annales Goephysicae 27:2633-2642 (2009).

This paper presents a subjective search for North Sea Draupner-like freaque waves from wave measurement data available in the northeastern coastal waters of Taiwan during Typhoon Krosa, October 2007. Not knowing what to expect, we found rather astonishingly that there were more Draupner-like freaque wave types during the build-up of the storm than we ever anticipated. As the conventional approach of defining freaque waves as Hmax/Hs > 2 is ineffective to discern all the conspicuous cases we found, we also tentatively proposed two new indices based on different empirical wave grouping approaches which hopefully can be used for further development of effective indexing toward identifying freaque waves objectively.

Lu, Y., S.A. LUDSIN, D.L. FANSLOW, and S.A. POTHOVEN. Comparison of three microquantity techniques for measuring total lipids in fish. Canadian Journal of Fisheries and Aquatic Sciences 65:2233-2241 (2008).

To measure lipids in juvenile and adult fishes, we refined three microquantity approaches (microgravimetric, microcolorimetric sulfophosphovanillan (SPV), and Iatroscan thin layer chromatography – flame ionization detection (TLC–FID)) that were originally developed to measure lipids in small aquatic invertebrates. We also evaluated their precision and comparability by quantifying the total lipid content of age-1+ walleye (Sander vitreus), yellow perch (Perca flavescens), and lake whitefish (Coregonus clupeaformis) collected in Lake Erie (US–Canada), Lake Michigan (USA), and Muskegon Lake (Michigan, USA). Our findings demonstrate that (i) microquantity approaches provide estimates of total lipids in juvenile and adult fishes similar to those of more traditional macroquantity approaches, (ii) the microcolorimetric SPV and microgravimetric approaches produce near identical estimates of total lipid content, and (iii) the Iatroscan TLC–FID approach underestimates total lipids relative to the other approaches for individuals with high lipid levels. Ultimately, our research makes available additional techniques for measuring total lipid content of fishes that are less expensive than traditional techniques, owing to a reduced need for large quantities of samples and solvents.

MacHutchon, K.R., W.J. Wessels, C.H. Wu, and P.C. LIU. The use of streamed digital video data and Binocular Stereoscopic Image System (BISIS) processing methods to analyse ocean wave field kinematics. Proceedings of the ASME 2009 28th International Conference on Ocean, Offshore, and Arctic Engineering OMAE2009, Honolulu, HI, May 31-June 5, 2009. American Society of Mechanical Engineers, 7 pp. (2009). 20090024DNP.pdf

The kinematics of short crested steep and breaking waves in the ocean is a subject that is best studied spatially, in the time domain, to obtain a good understanding of the multi-directional spreading of energy, which is dependant on strongly non-linear wave interactions in the system. The paper will cover the collection, recording and processing of streamed sea surface image data, obtained simultaneously from multiple digital video cameras, for analysis using stereoscopic image processing methods to provide information on the kinematics of ocean wave fields. The data streaming architecture, which will be reviewed, incorporates an advanced laptop computer and two to three stand-alone digital video cameras which are all linked through a gigabit ethernet network connection with sufficient bandwidth to simultaneously transfer the image data from the cameras to hard drive storage. The modifications to the laptop computer comprise the provision of increased processing capacity to enable it to accept and process large IP frames simultaneously. The system has the capacity to continuously record images, at a rate of up to 60 frames per second, for periods of up to one hour. It includes an external triggering mechanism, which is synchronised to a micro-second, to ensure that stereo pairs of images are captured simultaneously. Calibration of the cameras, and their stereoscopic configuration, is a critical part of the overall process, and we will discuss how ill-conditioned and singular matrices, which can prevent the determination of required intrinsic and extrinsic parameters, can be avoided. The paper will include examples of wave field image data which has been collected using streamed digital video data and Binocular Stereoscopic Image System (BiSIS) processing methods. It will also give examples digital video images and dimensional wave field data which has been collected and processed using the Automated Trinocular Stereoscopic Imaging Systems (ATSIS) methods. Both of these systems provide a valuable means of analysing irregular, non-linear, short crested waves, which leads to an improved understanding of ocean wave kinematics.

McCORMICK, M.J., T.O. Manley, D. BELETSKY, A.J. FOLEY, and G.L. FAHNENSTIEL. Tracking the surface flow in Lake Champlain. Journal of Great Lakes Research 34:721-730 (2008).

Understanding the hydrodynamics of Lake Champlain is a basic requirement for developing forecasting tools to address the lake’s environmental issues. In 2003 through 2005, surface drifting buoys were used to help characterize the circulation of the main body and northeast region (Inland Sea) of the lake. Progressive vector diagrams of over-lake winds when compared to drifter trajectories suggest the presence of gyre-like circulation patterns. Drifter statistics suggest average current speeds of 10 cm s–1 and were predominantly northward (+ V) due to northerly-directed winds and lake geometry. Singleparticle eddy diffusivities on the order of 106 cm2 s–1 were calculated which is consistent with results from the Great Lakes and in some oceanic regions. However, the Lagrangian length and time scales, a measure of flow decorrelation scales, were in general smaller than seen in the Great Lakes, which is a natural consequence of the smaller basin size of Lake Champlain relative to the Great Lakes.

McCORMICK, M.J., and D.J. SCHWAB. Observations of currents in Saginaw Bay, Lake Huron. Aquatic Ecosystem Health and Management 11(2):182-189 (2008).

During June 1991 through June 1994 six current meter moorings were deployed in the outer region of Saginaw Bay, Lake Huron to study the bay’s dynamics and interaction with Lake Huron. Two current meters were configured on each subsurface mooring at 14 m below the water surface and 2 m above the bottom and current speed, direction and water temperature were recorded at 15 minute intervals. These data represent nearly 1.2 million observations and are the longest continuous set of observations conducted anywhere in Lake Huron and the first ever winter observations conducted in Saginaw Bay. The winter months showed the highest mean currents from the moorings closest to Lake Huron while the stratified season showed high mean currents at the moorings located in the bay proper. There was little consistency in mean flow vectors other than the bottom currents at the southeastern mooring which showed consistent flow from the bay into Lake Huron. Only a small fraction of the kinetic energy was contained in the mean flow. The variability in the orientation of the principal axes of variation on semiannual to inter-annual time scales suggests using caution in generalizing about circulation patterns based solely upon limited data sets.

Millie, D.F., G.L. FAHNENSTIEL, J. DYBLE BRESSIE, R.J. Pigg, R.R. Rediske, D.M. Klarer, P.A. Tester, and R.W. Litaker. Late-summer phytoplankton in western Lake Erie (Laurentian Great Lakes): bloom distributions, toxicity, and environmental influences. Aquatic Ecology:20 pp. (DOI:10.1007/s10452-009-9238-7) (2009).

Phytoplankton abundance and composition and the cyanotoxin, microcystin, were examined relative to environmental parameters in western Lake Erie during late-summer (2003–2005). Spatially explicit distributions of phytoplankton occurred on an annual basis, with the greatest chlorophyll (Chl) a concentrations occurring in waters impacted by Maumee River inflows and in Sandusky Bay. Chlorophytes, bacillariophytes, and cyanobacteria contributed the majority of phylogenetic-group Chl a basin-wide in 2003, 2004, and 2005, respectively. Water clarity, pH, and specific conductance delineated patterns of group Chl a, signifying that water mass movements and mixing were primary determinants of phytoplankton accumulations and distributions. Water temperature, irradiance, and phosphorus availability delineated patterns of cyanobacterial biovolumes, suggesting that biotic processes (most likely, resource-based competition) controlled cyanobacterial abundance and composition. Intracellular microcystin concentrations corresponded to Microcystis abundance and environmental parameters indicative of conditions coincident with biomass accumulations. It appears that environmental parameters regulate microcystin indirectly, via control of cyanobacterial abundance and distribution.

NALEPA, T.F., D.L. FANSLOW, and G.A. LANG. Transformation of the offshore benthic community in Lake Michigan: Recent shift from the native amphipod Diporeia spp. to the invasive mussel Dreissena rostriformis bugensis. Freshwater Biology 54(3):466-479 (2009).

1. The native amphipod Diporeia spp. was once the dominant benthic organism in Lake Michigan and served as an important pathway of energy flow from lower to upper trophic levels. Lake-wide surveys were conducted in 1994 ⁄1995, 2000 and 2005, and abundances of Diporeia and the invasive bivalves Dreissena polymorpha (zebra mussel) and Dreissena rostriformis bugensis (quagga mussel) were assessed. In addition, more frequent surveys were conducted in the southern region of the lake between 1980 and 2007 to augment trend interpretation. 2. Between 1994/1995 and 2005, lake-wide density of Diporeia declined from 5365 to 329 m-2, and biomass (dry weight, DW) declined from 3.9 to 0.4 g DW m-2. The percentage of all sites with no Diporeia increased over time: 1.1% in 1994/1995, 21.7% in 2000 and 66.9% in 2005. On the other hand, total dreissenid density increased from 173 to 8816 m-2, and total biomass increased from 0.4 to 28.6 g DW m-2. Over this 10-year time period, D. r. bugensis displaced D. polymorpha as the dominant dreissenid, comprising 97.7% of the total population in 2005. In 2007, Diporeia was rarely found at depths shallower than 90 m and continued to decline at greater depths, whereas densities of D. r. bugensis continued to increase at depths greater than 50 m.  3. The decline in Diporeia occurred progressively from shallow to deep regions, and was temporally coincident with the expansion of D. polymorpha in nearshore waters followed by the expansion of D. r. bugensis in offshore waters. In addition, Diporeia density was negatively related to dreissenid density within and across depth intervals; the latter result indicated that dreissenids in shallow waters remotely influenced Diporeia in deep waters. 4. With the loss of Diporeia and increase in D. r. bugensis, the benthic community has become a major energy sink rather thana pathway to upper trophic levels. With this replacement of dominant taxa, we estimate that the relative benthic energy pool increased from 17 to 109 kcal m-2 between 1994/1995 and 2005, and to 342 kcal m-2 by 2007. We project that previously observed impacts on fish populations will continue and become more pronounced as the D. r. bugensis population continues to expand in deeper waters.

NALEPA, T.F., S.A. POTHOVEN, and D.L. FANSLOW. Recent changes in benthic macroinvertebrate populations in Lake Huron and impact on the diet of lake whitefish (Coregonus clupeaformus). Aquatic Ecosystem Health and Management 12(1):2-10 (2009).

Surveys of the benthic macroinvertebrate community were conducted in the main basin of Lake Huron in 2000 and 2003, and corresponding studies of lake whitefish diets were conducted in 2002-2004. Populations of three major benthic taxa, Diporeia spp., Sphaeriidae, and Chironomidae, declined dramatically between 2000 and 2003, with densities declining 57%, 74%, and 75% over this 3-year period. By 2003, Diporeia, an important food source for lake whitefish, was gone or rare at depths <50 m except in the far northeastern portion of the lake. In contrast, densities of the Dreissena bugensis (quagga mussel) increased between 2000 and 2003, particularly at the 31-50 m depth interval, while densities of the zebra mussel Dreissena polymorpha remained stable. As expected, the diet of lake whitefish varied with fish size. Age-0 lake whitefish fed mainly on zooplankton, most of which were Daphnia (98%). Medium lake whitefish (<350 mm excluding age-0 fish) fed mainly on zooplankton, Chironomidae, and Dreissena bugensis, and large lake whitefish (350 to 688 mm) fed mainly on D. bugensis and Gastropoda. The diet of medium and large lake whitefish reflected the changing nature of the benthic community; that is, Diporeia was rarely found in the diet while D. bugensis played a prominent role. Since Diporeia has a much higher energy content than D. bugensis, contrasting density trends in the two organisms will have long term consequences to the relative health of lake whitefish populations in the lake.

Pichlová-Ptacníková, R., and H.A. VANDERPLOEG. The invasive cladoceran Cerocopagis pengoi is a generalist predator capable of feeding on a variety of prey species of different sizes and escape abilities. Fundamental and Applied Limnology 173(4):267-279 (2009). 20090018DNP.pdf

We carried out a comprehensive exploration of predation by the invasive predatory cladoceran Cercopagis pengoi in the laboratory. A range of potential prey was offered to the predator, including all major summer nearshore zooplankton taxa in Lake Michigan; we used prey in different concentrations from 5 to 100 ind. L–1. We found that Cercopagis is a generalist capable to consume a variety of prey species, including small and large prey, and slowly and rapidly swimming prey. Consumption rates increased with concentration in several species, but did not saturate even at the highest concentration tested (40 or 100 ind. L–1). Cladocerans were consumed at a higher rate than copepods. Cercopagis was able to catch and handle prey of nearly its own body size to prey about seventeen times smaller; however, it did not show any clear size preference within this range. In contrast to most indigenous Great Lakes zooplankton,  Cercopagis can efficiently feed on veligers of the zebra mussel, another invader from the Ponto-Caspian region.

Piehler, M.F., J. DYBLE, P.H. Moisander, A.D. Chapman, J. Hendrickson, and H.W. Paerl. Interactions between nitrogen dynamics and the phytoplankton community in Lake George, Florida, USA. Lake and Reservoir Management 25(1):1-14 (2009). 20090030DNP.pdf

Nutrient addition bioassays were conducted to examine the relationship between inorganic nutrient enrichment and phytoplankton community structure and function in Lake George in the St. Johns River System, Florida, USA. Additionally, a nitrogen budget for the lake was developed and included data from the period of this study. We identified the factors that affected cyanobacterial productivity, prevalence, and nitrogen (N2) fixation. The importance of N2 fixation to the nitrogen (N) budget of the system was also assessed. We hypothesized that N2 fixation significantly contributed to the Lake George N budget and that changing the nutrient conditions in manipulative experiments would affect rates of N2 fixation and composition of the phytoplankton, particularly the N2-fixing community. Phytoplankton primary productivity in Lake George was stimulated by the addition of both N and phosphorus (P). Phytoplankton biomass accumulation was most often enhanced by the combined addition of N and P; however, N alone was also often stimulatory. When detected, N2 fixation was always stimulated by P additions. Short-term changes in phytoplankton community composition included taxonomic shifts in response to nutrient manipulations. Fixation of N2 appeared to be a significant contributor to the N load to the lake. Human impacts that change the loading of N, P, or both N and P to Lake George may affect phytoplankton community structure (composition and biomass) and function (primary productivity and N2 fixation). These changes could have consequences for biogeochemical cycling in Lake George and potentially through the freshwater-marine continuum. Continuing nutrient management efforts in this and other similar systems must account for the activity of N2-fixing cyanobacteria, as products (carbon fixation) and drivers (sources of new nitrogen) of eutrophication.

POTHOVEN, S.A., H.A. VANDERPLOEG, S.A. Ludsin, T.O. HÖÖK, and S.B. BRANDT. Feeding ecology of emerald shiners and rainbow smelt in Lake Erie. Journal of Great Lakes Research 35:190-198 (2009).

To better understand the feeding ecology of two important Laurentian Great Lakes prey species, rainbow smelt Osmerus mordax and emerald shiners Notropis atherinoides, we quantified the diet composition, selectivity, daily ration, and diet overlap of both species in offshore central Lake Erie during May through October 2005, which spanned a period of severe hypolimnetic hypoxia (<2 mg O2/L). Rainbow smelt fed upon a variety of prey taxa, including zooplankton, chironomid pupae and larvae, and fish, whereas emerald shiners primarily consumed cladocerans, if available. In turn, diet overlap between rainbow smelt and emerald shiners was low except during September when hypolimnetic hypoxia reduced rainbow smelt access to benthic prey. Rainbow smelt most frequently selected chironomid pupae, while emerald shiners generally selected pupae or large predatory cladocerans (Leptodora or Bythotrephes). Daily ration and individual consumption by rainbow smelt were 54–68% less during hypoxia than at the same site during stratified pre-hypoxic or mixed post-hypoxic conditions. Although emerald shiner daily ration and individual consumption decreased between pre-hypoxic and hypoxic periods, it continued to decrease during the posthypoxic period, suggesting that reduced consumption may not have been linked to hypoxic conditions. Ultimately, our findings suggest that emerald shiners are as important regulator of zooplankton abundance in the Great Lakes as rainbow smelt, given their potentially high mass-specific consumption rates, selectivity and diet patterns, and current high abundance.

Rao, Y.R., N. HAWLEY, M.N. Charlton, and W.M. Schertzer. Physical processes and hypoxia in the central basin of Lake Erie. Limnology and Oceanography 53(5):2007-2020 (2008).

The circulation and exchange processes during summer stratification were examined using time-series data of horizontal velocity, temperature, and dissolved oxygen profiles during 2004 and 2005 in the mid-central basin of Lake Erie. The current and temperature spectra showed a prominent peak at around 18 h, indicating the presence of clockwise rotating inertial waves. The mean bottom currents were strong (>0.1 m s-1) and flowed in opposite direction to winds because of the surface pressure gradient due to wind set-up. The general range of horizontal exchange coefficients in the central basin is 0.2–1.2 m2 s-1. Vertical exchange coefficients varied from 1 x 10-5 to 1 x 10-4 m2 s-1. The high values usually occurred in the surface layer because of surface winds. The source of turbulent energy is current shear due to near-inertial oscillations in and above the thermocline and shearing stress due to the effect of mean currents and wave-induced motions during energetic wind events at the lake bottom. During strong wind episodes significant wave-induced currents were observed close to the bottom. The short-term oxygen depletion rates varied considerably between +0.87 mg L-1 d-1 and -1.16 mg L-1 d-1 in 2004 mainly because of physical processes in the central basin. When the hypolimnion depth is sufficiently thick (4 m), shortterm changes in dissolved oxygen concentrations were partly due to vertical mixing and partly due to horizontal transport and mixing.

REID, D.F., and R. STURTEVANT. Ballast water and aquatic nuisance species introductions in the Great Lakes. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2009).

Over the last two centuries the Great Lakes have been invaded by aquatic nonindigenous species (ANS) moving via a broad array of vectors, including transoceanic shipping. Ships are believed to be responsible for ANS additions starting in the 1860’s through disposal of solid ballast. The opening of the St. Lawrence Seaway in 1959 resulted in a substantial increase in the importance of ballast water as a vector for the introduction of nonindigenous species. Ballast water is used to supply stability on ships that have no load. It is loaded on before departure and often carries stowaways in the form of tiny organisms. Ship discharge of ballast water is considered the most likely source for the majority of ANS additions in the Great Lakes since 1959. Due to the invasion of zebra mussels in the late-1980s, mandatory ballast water management regulations were established in 1993 for all ships entering the Great Lakes with pumpable ballast water. Under these regulations, ships are required to replace ballast water with saltwater from the middle of the ocean in a process known as ballast water exchange (BWE).

Rose, K.A., A.T. ADAMACK, C.A. Murphy, S.E. Sable, S.E. Kolesar, J.K. Craig, D.L. Breitburg, P. Thomas, M.H. Brouwer, C.F. Cerco, and S. Diamond. Does hypoxia have population-level effects on coastal fish? Musing from the virtual world. Journal of Experimental Marine Biology and Ecology 381:S188-S203 (2009). 20090027DNP.pdf

Hypoxia is often associated with increasing nutrient loadings and has clear mortality effects on sessile organisms, but its population effects on mobile organisms in coastal environments are uncertain. The evidence for hypoxia having population level effects is laboratory experiments, many examples of localized effects in nature, a few population-level examples, fish kills, and intuition. Despite the perception by many people, none of these provide conclusive evidence of widespread population responses to hypoxia.We synthesize the results from seven ecological simulation models that examined how low dissolved oxygen (DO) affected fish at the individual, population, and community levels. These models represent a variety of species, simulate the dynamics at a range of temporal scales and spatial scales, and impose a variety of subsets of possible DO effects. Several patterns emerged from the accumulated results. First, predicted responses were large in simpler models, and small to large in more complex models. Second, while the main effects of increased hypoxia were generally small to moderate, there were instances of relatively large indirect effects and interaction effects. Indirect effects involved growth and mortality responses due to altered spatial distribution (rather than due directly to DO) and food web interactions. Interaction effects were larger responses to hypoxia when other factors were at certain levels (e.g., responses at low versus high fish densities). Interactions also occurred when the predicted responses were larger than would be expected by the sum of the separate effects. Third, accurate information on exposure and degree of avoidance of low DO were critical unknowns. Our interpretations should be viewed as suggestive rather than definitive. The patterns described were based on a collection of modeling results that were not designed to be compared to each other. A quick look at other models seems to confirm our patterns, or at minimum, does not contradict our patterns. Quantifying the effects of hypoxia on fish populations, whether large or small, is critical for effective management of coastal ecosystems and for costeffective and efficient design of remediation actions. The potential for interaction and indirect effects complicates field study and management. Improving our predictions of the effects of hypoxia on fish populations and communities has moved from a computational issue to a biological issue. We seem to be making progress on monitoring and modeling movement behavior, but progress is slower in food web theory and empirical research and in quantifying interspecific interactions and habitat quality in terms of process rates that relate to population dynamics.

RUBERG, S.A., E. Guasp, N. HAWLEY, R.W. MUZZI, S.B. BRANDT, H.A. VANDERPLOEG, J.C. LANE, T.C. MILLER, and S.A. CONSTANT. Societal benefits of the real-time coastal observation network (ReCON): Implications for municipal drinking water quality. Marine Technology Society Journal 42(3):103-109 (2008).

Environmental conditions on Lake Erie in summer 2006 produced hypoxic waters (1.2 mg/l), with characteristic low pH (7.2), low temperature (18°C) and high manganese levels, negatively impacting water processing at the Cleveland Water Department. A ReCON system deployed in 2005 recorded the onset of similar conditions and is used to explain the episodic nature of the event. Internal waves initiated by winds can propagate around the central basin of Lake Erie for several days explaining the cyclical nature of the event. Future deployments of a ReCON buoy system in Lake Erie’s central basin will provide real-time observations of temperature and dissolved oxygen to water department managers. The buoy will function as an early warning system for the detection of low oxygen and the onset of internal waves responsible for delivering hypoxic waters to water intakes thus ensuring the quality of drinking water for approximately 1.5 million residents at Cleveland, OH.

RUBERG, S.A., S.T. Kendall, B.A. Biddanda, T. Black, S.C. Nold, W.R. Lusardi, R. Green, T. Casserley, E. Smith, T.G. Sanders, G.A. LANG, and S.A. CONSTANT. Observations of the Middle Island sinkhole in Lake Huron: A unique hydrogeologic and glacial creation of 400 million years. Marine Technology Society Journal 42(4):12-21 (2009).

In the northern Great Lakes region, limestone sediments deposited some 400 million ybp during the Devonian era have experienced erosion, creating karst features such as caves and sinkholes. The groundwater chemical constituents of the shallow seas that produced these rock formations now contribute to the formation of a unique physical (sharp density gradients), chemical (dissolved oxygen-depleted, sulfate-rich), and biological (microbe-dominated) environment in a submerged sinkhole near Middle Island in freshwater Lake Huron. A variety of methods including aerial photography, physico-chemical mapping, time series measurements, remotely operated vehicle (ROV) survey, diver observations, and bathymetric mapping were employed to obtain a preliminary understanding of sinkhole features and to observe physical interactions of the system’s groundwater with Lake Huron. High conductivity ground water of relatively constant temperature hugs the sinkhole floor creating a distinct sub-ecosystem within this Great Lakes ecosystem. Extensive photosynthetic purple cyanobacterial benthic mats that characterize the benthos of this shallow sinkhole were strictly limited to the zone of ground water influence.

Ruetz, D.R., D.L. Strouse, and S.A. POTHOVEN. Energy density of introduced round goby compared with four native fishes in a Lake Michigan tributary. Transactions of the American Fisheries Society 138:938-947 (2009).

The round goby Neogobius melanostomus is an invasive species that has changed Great Lakes food webs and become an important prey for many predators. We tested whether the round goby from a Lake Michigan tributary was energetically equivalent to four native fishes: mottled sculpin Cottus bairdii, johnny darter Etheostoma nigrum, bluntnose minnow Pimephales notatus, and rock bass Ambloplites rupestris. We found positive linear relationships between energy density and the percent dry weight of a fish for each species. We also found evidence of temporal and spatial variation in round goby energy density. Energy density was lower in spring and summer than in fall. The spatial variation in energy density may be linked to the inclusion of the low quality prey, dreissenid mussels, in the diets of larger round goby. For a given size, the johnny darter and bluntnose minnow had the highest energy density while mottled sculpin had the lowest. Our results show that the energy density of the round goby is intermediate to those of the four native fishes, suggesting that the round goby is an energetically average prey in a Lake Michigan tributary.

RUTHERFORD, E.S. Lake Michigan's tributary and nearshore fish habitats. In The State of Lake Michigan in 2005. D.F. Clapp and W. Horns (eds.). Great Lakes Fishery Commission Special Publication 08-02. Great Lakes Fishery Commission, Ann Arbor, MI, pp. 7-17 pp. (2008).

The importance of preserving and restoring habitat for fish was implicitly recognized in the guiding principles and goals of the Great Lakes Water Quality Agreement (GLWQA) (International Joint Commission 1988), in A Joint Strategic Plan for Management of Great Lakes Fisheries (hereafter, Joint Plan) (Great Lakes Fishery Commission 1997), and most recently in the Great Lakes Regional Strategy (Great Lakes Regional Collaboration 2005). The GLWQA of 1978 called for an ecosystem approach to restore and maintain the chemical, physical, and biological integrity of waters within the Great Lakes basin (Bertram et al. 2005) and recognized the interdependence of living organisms with their physical and chemical habitats (Trudeau 2005). Lake management plans (LaMPs) were established to address critical pollutants and other stresses to each lake and included development of remedial action plans for Areas of Concern (AOCs) that have serious pollution problems impairing beneficial use by humans, fish, or wildlife (U.S. EPA 2004a). In 2000, the Lake Michigan LaMP was developed to comply with provisions in the GLWQA and to guide management practices to maximize achievement of ecosystem goals and restore beneficial use impairments cited in the GLWQA. Many of the subgoals of the management plan (and the environmental indicators used to evaluate those subgoals) address restoration and protection of fish health, biotic integrity, and habitat productivity. Progress towards meeting the goals is reported on a biennial basis (e.g., U.S. EPA 2004b). The Great Lakes Regional Strategy (Great Lakes Regional Collaboration 2005) is a recent wide-ranging, cooperative effort to design and implement a strategy for the restoration, protection, and sustainable use of the Great Lakes, with specific suggestions for addressing impairments to fish communities in tributary, coastal wetland, and nearshore habitats.

Santagata, S., K. Bacela, D.F. REID, K.A. McLean, J.S. Cohen, J.R. Cordell, C.W. Brown, T.H. JOHENGEN, and G.M. Ruiz. Concentrated sodium chloride brine solutions as an additional treatment for preventing the introduction of nonindigenous species in the ballast tanks of ships declaring no ballast on board. Environmental Toxicology and Chemistry 28(2):346-353 (2009). 20090002DNP.pdf

Currently, seawater flushing is the only management strategy for reducing the number of viable organisms in residual sediments and water of ballast tanks of vessels declaring no ballast on board (NOBOB) that traffic ports of the eastern United States. Previously, we identified several species of freshwater and brackish-water peracarid crustaceans able to survive the osmotic shock that occurs during open-ocean ballast water exchange and, potentially, to disperse over long distances via ballasted ships and NOBOB vessels. We tested the efficacy of concentrated sodium chloride brine solutions as an additional treatment for eradicating the halotolerant taxa often present in the ballast tanks of NOBOB ships. The lowest brine treatments (30 ppt for 1 h) caused 100% mortality in several species of cladocerans and copepods collected from oligohaline habitats. Several brackish-water peracarid crustaceans, however, including some that can survive in freshwater as well, required higher brine concentrations and longer exposure durations (45–60 ppt for 3–24 h). The most resilient animals were widely introduced peracarid crustaceans that generally prefer mesohaline habitats but do not tolerate freshwater (required brine treatments of 60–110 ppt for 3–24 h). Brine treatments (30 ppt) also required less time to cause 100% mortality for eight taxa compared with treatments using 34 ppt seawater. Based on these experiments and published data, we present treatment strategies for the ballast tank biota often associated with NOBOB vessels entering the Great Lakes region. We estimate the lethal dosage of brine for 95% of the species in our experiments to be 110 ppt (95% confidence interval, 85–192 ppt) when the exposure time is 1 h and 60 ppt (95% confidence interval, 48–98 ppt) when the exposure duration is 6 h or longer.

SCHWAB, D.J., D. BELETSKY, J. DePinto, and D.M. Dolan. A hydrodynamic approach to modeling phosphorus distribution in Lake Erie. Journal of Great Lakes Research 35:50-60 (2009).

The purpose of this paper is to show how a high-resolution numerical circulation model of Lake Erie can be used to gain insight into the spatial and temporal variability of phosphorus (and by inference, other components of the lower food web) in the lake. The computer model simulates the detailed spatial and temporal distribution of total phosphorus in Lake Erie during 1994 based on tributary and atmospheric loading, hydrodynamic transport, and basin-dependent net apparent settling. Phosphorus loads to the lake in 1994 were relatively low, about 30% lower than the average loads for the past 30 years. Results of the model simulations are presented in terms of maps of 1) annually averaged phosphorus concentration, 2) temporal variability of phosphorus concentration, and 3) relative contribution of annual phosphorus load from specific tributaries. Model results illustrate that significant nearshore to offshore gradients occur in the vicinity of tributary mouths and their along-shore plumes. For instance, the annually-averaged phosphorus concentration can vary by a factor of 10 from one end of the lake to the other. Phosphorus levels at some points in the lake can change by a factor of 10 in a matter of hours. Variance in phosphorus levels is up to 100 times higher near major tributary mouths than it is in offshore waters. The model is also used to estimate the spatial distribution of phosphorus variability and to produce maps of the relative contribution of individual tributaries to the annual average concentration at each point in the lake.

STOW, C.A., J. Jolliff, D.J. McGillicuddy, S.C. Doney, J.I. Allen, M.A.M. Friedrichs, K.A. Rose, and P. Wallhead. Skill assessment for coupled biological/physical models of marine systems. Journal of Marine Systems 76:4-15 (2009). 20090003DNP.pdf

Coupled biological/physical models of marine systems serve many purposes including the synthesis of information, hypothesis generation, and as a tool for numerical experimentation. However, marine system models are increasingly used for prediction to support high-stakes decision-making. In such applications it is imperative that a rigorous model skill assessment is conducted so that the model's capabilities are tested and understood. Herein, we review several metrics and approaches useful to evaluate model skill. The definition of skill and the determination of the skill level necessary for a given application is context specific and no single metric is likely to reveal all aspects of model skill. Thus, we recommend the use of several metrics, in concert, to provide a more thorough appraisal. The routine application and presentation of rigorous skill assessment metrics will also serve the broader interests of the modeling community, ultimately resulting in improved forecasting abilities as well as helping us recognize our limitations.

STOW, C.A., E.C. Lamon, S.S. Qian, P.A. Soranno, and K.H. Reckhow. Bayesian hierarchical/multilevel models for inference and prediction using cross-system lake data. In Real World Ecology: Large Scale and Long-Term Case Studies and Methods. S. Carstenn S. Miao, and M. Nungesser (eds.). Springer Science and Business Media, New York, NY, 111-136 pp. (2009). 20090013DNP.pdf

Cross-system studies are commonly used for large-scale ecological inference (Cole et al. 1991). Many processes change slowly within a particular ecosystem, thus long time periods can be required to measure how changes in one process may influence changes in another. By using data from many systems, researchers essentially substitute space for time, assuming commonanlity among the systems being compared. Comparing characteristics among systems helps researchers identify patterns that provide clues for understanding ecosystem function, generate testable hypotheses, and isolate cause-effect relationships.

STOW, C.A., and D. Scavia. Modeling hypoxia in the Chesapeake Bay: Ensemble estimation using a Bayesian hierarchical model. Journal of Marine Systems 76:244-250 (2009). 20090008DNP.pdf

Quantifying parameter and prediction uncertainty in a rigorous framework can be an important component of model skill assessment. Generally, models with lower uncertainty will be more useful for prediction and inference than models with higher uncertainty. Ensemble estimation, an idea with deep roots in the Bayesian literature, can be useful to reduce model uncertainty. It is based on the idea that simultaneously estimating common or similar parameters among models can result in more precise estimates. We demonstrate this approach using the Streeter–Phelps dissolved oxygen sag model fit to 29 years of data from Chesapeake Bay. Chesapeake Bay has a long history of bottom water hypoxia and several models are being used to assist management decision-making in this system. The Bayesian framework is particularly useful in a decision context because it can combine both expert-judgment and rigorous parameter estimation to yield model forecasts and a probabilistic estimate of the forecast uncertainty.

Stroud, J.R., B.M. Lesht, D.J. SCHWAB, D. BELETSKY, and M.L. Stein. Assimilation of satellite images into a sediment transport model of Lake Michigan. Water Resources Research 45(W02419):16 pp. (DOI:10.1029/2007WR006747) (2009). 20090017DNP.pdf

In this paper we develop and examine several schemes for combining daily images obtained from the Sea-viewing Wide Field Spectrometer (SeaWiFS) with a two dimensional sediment transport model of Lake Michigan. We consider two data assimilation methods, direct insertion and a kriging-based approach, and perform a forecasting study focused on a 2-month period in spring 1998 when a large storm caused substantial amounts of sediment resuspension and horizontal sediment transport in the lake. By beginning with the simplest possible forecast method and sequentially adding complexity we are able to assess the improvements offered by combining the satellite data with the numerical model. In our application, we find that data assimilation schemes that include both the data and the lake dynamics improve forecast root mean square error by 40% over purely model-based approaches and by 20% over purely data-based approaches.

STURTEVANT, R., and A. MARSHALL. Educator House Call: On-line data for educators' needs assessment - summary report. NOAA Technical Memorandum GLERL-149. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 9 pp. (2009).

The overreaching purpose of this focus group was to advise NOAA and NOAA partners on the best ways to make NOAA data available to educators with a focus on online delivery. There was also an emphasis on inquiry-based education.

STURTEVANT, R.A., L. Ge, R. Nagy, and R. Patel. Lake Michigan Food Web. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2009).

Pictorial presentation of the food web of Lake Michigan

STURTEVANT, R.A., L. Ge, R. Nagy, and R. Patel. Lake Erie Food Web. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2009).

Pictorial presentation of the food web of Lake Erie

STURTEVANT, R.A., L. Ge, R. Nagy, and R. Patel. Lake Ontario Food Web. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2009).

Pictorial presentation of the food web of Lake Ontario

STURTEVANT, R.A., L. Ge, R. Nagy, and R. Patel. Lake Huron Food Web. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2009).

Pictorial presentation of the food web of Lake Huron

STURTEVANT, R.A., L. Ge, R. Nagy, and R. Patel. Lake St. Clair Food Web. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2009).

Pictorial presentation of the food web of Lake St. Clair

STURTEVANT, R.A., L. Ge, R. Nagy, and R. Patel. Lake Superior Food Web. NOAA Great Lakes Environmental Research Laborataory, Ann Arbor, MI, 2 pp. (2009).

Pictorial presentation of the food web of Lake Superior

WANG, H.-Y., and T.O. HÖÖK. Eco-genetic model to explore fishing-induced ecological and evolutionary effects on growth and maturation schedules. Evolutionary Applications:438-455 (2009).

Eco-genetic individual-based models involve tracking the ecological dynamics of simulated individual organisms that are in part characterized by heritable parameters. We developed an eco-genetic individual-based model to explore ecological and evolutionary interactions of fish growth and maturation schedules. Our model is flexible and allows for exploration of the effects of heritable growth rates (based on von Bertalanffy and biphasic growth patterns), heritable maturation schedules (based on maturation reaction norm concepts), or both on individual- and population-level traits. In baseline simulations with rather simple ecological trade-offs and over a relatively short time period (<200 simulation years), simulated male and female fish evolve differential genetic growth and maturation. Further, resulting patterns of genetically determined growth and maturation are influenced by mortality rate and density-dependent processes, and maturation and growth parameters interact to mediate the evolution of one another. Subsequent to baseline simulations, we conducted experimental simulations to mimic fisheries harvest with two size-limits (targeting large or small fish), an array of fishing mortality rates, and assuming a deterministic or stochastic environment. Our results suggest that fishing with either size-limit may induce considerable changes in life-history trait expression (maturation schedules and growth rates), recruitment, and population abundance and structure. However, targeting large fish would cause more adverse genetic effects and may lead to a population less resilient to environmental stochasticity.

WANG, J., H. HU, K. Mizobata, and S. Saitoh. Seasonal variations of sea ice and ocean circulation in the Bering Sea: A model-data fusion study. Journal of Geophysical Research 114(C02011):24 pp. (DOI:10.1029/2008JC004727) (2009).   20090011DNP.pdf

A 9-km coupled ice-ocean model (CIOM) was implemented in the entire Bering Sea to investigate seasonal cycles of sea ice and ocean circulation under atmospheric forcing. Sea ice cover with a maximum of 0.6 x 106 km2 in February to late March was reasonably reproduced by the Bering-CIOM and validated by Special Sensor Microwave/Imager (SSM/I) measurements. The model also captures some important spatial variability and downscaling processes such as polynyas and ridging, which the SSM/I measurements cannot reproduce because of their coarse (25 km) resolution. There are two distinct surface ocean circulation patterns in winter and summer on the Bering shelves because of the dominant winds, which are northeasterly in winter and southwesterly in summer. Summer low-temperature, high-salinity water mass (<3 oC) on the Bering shelf is formed locally during winter because of strong vertical convection caused by salt injection when ice forms, wind, and wind-wave mixing on the shelf. The northward volume transport across the 62.5 oN line, with an annual mean of 0.8 ± 0.33 Sv (1 Sv = 106 m3 s-1) that is consistent with the measurements in the Bering Strait, has barotropic structure, which transports heat flux (with an annual mean of 7.74 TW; 1 TW = 1012 W) northward. The Anadyr Current advects warmer, saltier water northward during summer; nevertheless, it reverses its direction to southward during winter because of predominant northeasterly and northerly wind forcing. Therefore, the Anadyr Current advects cold, salty water southward. The volume transport on the broad midshelf is northward year round, advecting heat (3.3 ± 2.4 TW) and freshwater (- 8 ± 10  x 104 practical salinity unit (psu) m3 s-1) northward. One important finding is that the Anadyr Current and the midshelf current are out of phase in volume and heat transports. The Alaskan Coastal Current also transports heat and freshwater northward on an annual basis. The Bering-CIOM also captures the winter dense water formation along the Siberian coast, which is promoted by the downwelling favorable northeasterly wind, and the summer upwelling due to the basin-scale upwelling favorable southwesterly wind, which brings up the cold, salty, and nutrient-rich water from the subsurface to the surface within a narrow strip along the west coast. This upwelling found in the model was also confirmed by satellite measurements in this study.

WANG, J., M. Jin, J. Takahashi, T. Suzuki, I.G. Polyakov, K. Mizobata, M. Ikeda, F.J. Saucier, and M. Meier. Modeling Arctic Ocean heat transport and warming episodes in the 20th century caused by the intruding Atlantic water. Chinese Journal of Polar Research 19(2):159-167 (2008).

This study investigates the Arctic Ocean warming episodes in the 20th century using both a high-resolution coupled global climate model and historical observations. The model, flux adjustment, reproduces well the Atlantic Water core temperature (AWCT) in the Arctic Ocean and shows that four largest decadalscale warming episodes occurred in the 1930s, 70s, 80s, and 90s, in agreement with the hydrographic observational data. The difference is that there was no pre-warming prior to the 1930s episode, while there were two pre-warming episodes in the 1970s and 80s prior to the 1990s, leading the 1990s into the largest and prolonged warming in the 20th century. Over the last century, the simulated heat transport via Fram Strait and the Barents Sea was estimated to be, on average, 31. 32 TW and 14. 82 TW, respectively, while the Bering Strait also provides 15.94 TW heat into the western Arctic Ocean. Heat transport into the Arctic Ocean by the Atlantic Water via Fram Strait and the Barents Sea correlates significantly with AWCT (C =0.75) at 0lag. The modeled North Atlantic Oscillation (NAO) index has a significant correlation with the heat transport (C =0.37). The observed AWCT has a significant correlation with both the modeled AWCT ( C =0.49) and the heat transport (C =0.41) . However, the modeled NAO index does not significantly correlate with either the observed AWeT (C = O. 03) or modeled AWCT (C = O. 16) at a zero-lag, indicating that the Arctic climate system is far more complex than expected. Key words Arctic Ocean, heat transport, warming episodes, modeling.

WANG, J., K. Mizobata, H. HU, M. Jin, S. Zhang, W. Johnson, K. Shimada, and M. Ikeda. Modeling seasonal variations of ocean and sea ice circulation in the Beaufort and Chukchi Seas: A model-data fusion study. Chinese Journal of Polar Research 19(2):168-184 (2008).

A 3. 8-km Coupled lee-Ocean Model (CIOM) was implemented to successfully reproduce many observed phenomena in the Beaufort and Chukchi seas, including the Bering-inflow-originated coastal ciurrent that splits into three branches: Alaska Coastal Water (ACW) , Central Channel, and Herald Valley branches. Other modeled phenomena include the Beaufort Slope Current (BSC), the Beaufort Gyre, the East Siberian Current (ESC), mesoscale eddies, seasonal landfast ice, sea ice ridging, shear, and deformalion. Many of these downscaling processes can only be captured by using a high-resolution CIOM. nested in a global climate model. The seasonal cycles for sea ice concentration, thickness, velocity, and other variables are well reproduced with solid validation by satellite measurements. The seasonal cycles for upper ocean dynamics and thermodynamics are also well reproduced, which include the formation of the cold saline layer due to the injection of salt during sea ice formation, the BSC, and the subsurface upwelling in winter that brings up warm, even more saline Atlantic Water along the shelfbreak and shelf along the Beaufort coast.

WANG, J., J. Zhang, E. Watanabe, M. Ikeda, K. Mizobata, J.E. Walsh, X. BAI, and B. Wu. Is the dipole anomaly a major driver to record lows in Arctic summer sea ice extent? Geophysical Research Letters 36(L05706):5 pp. (DOI:10.1029/2008GL036706) (2009). 20090014DNP.pdf

Recent record lows of Arctic summer sea ice extent are found to be triggered by the Arctic atmospheric Dipole Anomaly (DA) pattern. This local, second–leading mode of sea–level pressure (SLP) anomaly in the Arctic produced a strong meridional wind anomaly that drove more sea ice out of the Arctic Ocean from the western to the eastern Arctic into the northern Atlantic during the summers of 1995, 1999, 2002, 2005, and 2007. In the 2007 summer, the DA also enhanced anomalous oceanic heat flux into the Arctic Ocean via Bering Strait, which accelerated bottom and lateral melting of sea ice and amplified the ice–albedo feedback. A coupled ice–ocean model was used to confirm the historical record lows of summer sea ice extent.

Yang, X.Y., R.X. Huang, J. WANG, and D.X. Wang. Delayed baroclinic response of the Antarctic circumpolar current to surface wind stress. Science in China Series D: Earth Sciences 51(7):1036-1043 (2008). 20080050DNP.pdf

The Antarctic Circumpolar Current (ACC) responds to the surface windstress via two processes, i.e., the instant barotropic process and the delayed baroclinic process. This study focuses on the baroclinic instability mechanism in ACC, which was less reported in the literatures. Results show that the strengthening of surface zonal windstress causes the enhanced tilting of the isopycnal surface, leading to more intense baroclinic instability. Simultaneously, the mesoscale eddies resulting from the baroclinic instability facilitate the transformation of mean potential energy to eddy energy, which causes the remarkable decrease of the ACC volume transport with the 2-year lag time. This delayed negative correlation between the ACC transport and the zonal windstress may account for the steadiness of the ACC transport during last two decades.

Ordering GLERL Publications:

To order a copy of GLERL publications not available for downloading at this site, please contact:

Nicole Rice Information Services

NOAA Great Lakes Environmental Research Laboratory
4840 S. State Rd
Ann Arbor, MI 48108-9719 US
734-741-2055 (FAX