GLERL Publications with Abstracts

January 2009 - Present

Capitalized names represent GLERL authors.

To request hard copies of any of these publications, contact:

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).

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.

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.

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).

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 fromthe 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.

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.

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, doi:10.1029/2008JC005105):10 pp. (2009).

[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.

JOSEPH, S.T., L.A. CHAIMOWITZ, M.A. QUIGLEY, R.A. STURTEVANT, D.M. MASON, C.E. SELLINGER, J. WANG, and C. DeMARCHI. 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.

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.

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.

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 OMAE2909, Honolulu, HI, May 31-June 5, 2009. American Society of Mechanical Engineers, 7 pp. (2009).

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.

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 that a 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 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 lakewhitefish dietswere 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 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-Ptácníková, 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).

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.

POTHOVEN, S.A., H.A. VANDERPLEOG, 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.

REID, D.F., and R. STURTEVANT. Ballast water and aquatic nuisance species introductions in the Great Lakes. Fact Sheet. 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).

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 lowquality 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.

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).

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).

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 dta. 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 (2009).

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 mesure how changes in one process may influence changes in another. By using data from many systems, researchers essentially substitute space for time, assuming commanlity 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).

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 numerical sediment transport model of Lake Michigan. Journal of Geophysical Research 45(W02419, doi:10.1029/2007WR006747):16 PP. (2009).

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.

VANDERPLOEG, H.A., T.H. JOHENGEN, and J.R. LIEBIG. Feedback between zebra mussel selective feeding and algal composition affects mussel condition: did the regime changer pay a price for its success? Freshwater Biology:17 pp. (2009).

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

WANG, H.-Y., and T.O. HÖÖK. Eco-genetic model to explore fishing-induced ecological and evolutionary effects on growth and maturation schedules. Evolutionary Applications (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, doi:10.1029/2008JC004727):24 pp. (2009).

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., 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, doi:10.1029/2008GL036706):5 pp. (2009).

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.


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