GLERL Publication Abstracts: FY 2004

Publications List Key
Capitalized names represent GLERL authors.
* = Not available from GLERL.
** = Available in GLERL Library only.

As-Salek, J. A., and D. J. SCHWAB. High frequency water level fluctuations in Lake Michigan. Journal of Waterway, Port, Coastal and Ocean Engineering:45-53 (2004).

During certain meteorological events, water level oscillations up to 1.5 m with periods of less than 2 h have been observed in the Great Lakes. The squall line events of 7-11 March 1998, 29 May-2 June 1998, and 8-12 November 1998 in Lake Michigan, are analyzed by spectral and analytical methods. Dominant periods of less than 2 h are identified in the spectra of water level fluctuations and coherencies among the spectral peaks of water levels of different station pairs are calculated to determine whether the oscillations are localized or basin wide. Explicit numerical calculations of normal mode periods and structures using a Lanczos procedure show that the dominant periods in the observed data are consistent with the structures and periods of some of the calculated modes. The March 1998 and the November 1998 episodes show higher surges with a gradual rise of water level, while the episode of May 1998 shows an abrupt rise in the water level at Calumet Harbor and about ten times higher spectral signature than the former two. Many of the high-frequency modes have large amplitude at or near Calumet Harbor and the periods are close to the periods of edge waves that would be generated by a squall line similar to the May 1998 squall line. The trapping of energy and localized higher modes in a water body can work together to excite edge waves and localized seiches causing abrupt water level fluctuations.

ASSEL, R. A., F. H. QUINN, and C. E. SELLINGER. Hydro-climatic factors of the recent drop in Laurentian Great Lakes water levels. Bulletin of the American Meteorological Society 85(8):1143-1151 (2004).

High air temperatures resulted in unusually high evaporation rates and decreased basin runoff, producing the largest single-year drop in the levels of Lakes Michigan, Huron, and Erie in over 150 years of record.

ASSEL, R. A., S. Drobot, and T. E. CROLEY II. Improving 30-day Great Lakes ice cover outlooks. Journal of Hydrometeorology 5(4):713-717 (2004).

Prediction of Great Lakes ice cover is important for winter operations and planning activities. Current 30-day forecasts use accumulated freezing degree-days (AFDDs) to identify similar historical events and associated ice cover. The authors describe statistical models that relate future ice cover to current ice cover, AFDDs, and teleconnection indices, available on the day the forecast is made. These models are evaluated through Monte Carlo simulation and assess the potential of a perfect AFDD forecast in a regression between ice cover and AFDDs between the forecast date (first day of month) and the date for which the forecast is made (first day of next month)

ASSEL, R. A., S. Drobot, and T. E. CROLEY II. Improving monthly Great Lakes ice cover outlooks. NOAA Technical Memorandum GLERL-129. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 22 pp. (2004).

Prediction of ice growth in the Great Lakes is important for commercial navigation, channel maintenance, water level and flow regulation, and winter operations planning. Current 30-day forecasts, issued on the first of the month for the first of the following month, mainly use forecasts of air temperature. They enable calculation of accumulated freezing degree-days (AFDDs), which are used to identify similar historical events and associated ice cover as a forecast. More information is now available to ice forecasters, and we investigate its use in simple statistical models. The information considered here is limited to observations available at the time of a forecast, but include AFDDs, various telecommunication indices, and current ice cover. Additionally, the potential of AFDD forecasts is assessed in a statistical regression between ice cover and AFDDs during the month between the time of making the forecast and the start date of the forecast. (Actual AFDDs represent the best we could hope to forecast and so its use reveals the potential improvement that could be realized if a forecast of AFDD was developed.) Likewise, the potential of a mechanistic lake thermodynamics model is also assessed in a statistical correlation between ice cover and model outputs.

ASSEL, R. A. Lake Erie ice cover climatology -- basin averaged ice cover: winters 1898-2002. NOAA Technical Memorandum GLERL-128. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 15 pp. (2004).

Ice cover impacts the water balance of the lakes and lake flora and fauna by affecting energy and mass transfers from and to the lakes. Improved understanding of ice cover climatology is therefore needed for an improved understanding and forecasts of the winter lake ecosystem. The duration and extent of ice cover on the Great Lakes also has a major impact on the economy of the region by impeding and eventually stopping commercial navigation, interfering with hydropower production and cooling water intakes, and damaging shore structures. Assel (2003a) presents a climatology of Great Lakes ice cover for each Great Lake over the winters: 1973-2002 on a nominal spatial resolution of 2.5 km grid cells. The purpose of this report is to provide a different aspect of that climatology for Lake Erie, primarily, basin averages of ice concentration for the east, central, and west basins of that lake. This work is being done under the auspices of the Climatology of the Physical Environment in Lake Erie Project and as such is part of a coordinated effort to provide improved data for retrospective and interdisciplinary analyses of the relative roles of physical, chemical, and biological factors on the ecology of Lake Erie. Lake Erie is a good candidate for this research because it has a high population density, availability of long term data sets, a variety of physical, chemical, and biological forcing functions (including invasive species), and a wide variety of concerns including water quality (hypoxia/anoxia, harmful algal blooms,) water quantity (levels), and fisheries.

ASSEL, R. A. Great Lakes monthly and seasonal accumulations of freezing degree days -- winters 1898-2002. NOAA Technical Memorandum GLERL-127. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 36 pp. (2003).

This is the third in a series of reports on Great Lakes freezing degree-days (FDDs). The first and second reports included daily FDDs and seasonal maximum FDDs at individual stations for winters 1898-1977 and 1978-1983, respectively. This report updates the daily time series of FDDs for the winter seasons from 1984 through 2002. Results are presented within the context of a 105-winter record of monthly and seasonal FDDs at 18 stations around the shores of the Great Lake. Tabulations, graphics, statistics (average, standard deviation, maximum, minimum, ranked order), and winter severity classes are presented for 105-winter monthly and seasonal FDDs for beginning of month (BOM) dates at each station. A few examples of applications of these data are discussed briefly. Electronic files of the daily FDDs (1984-2002) and monthly and seasonal accumulation on BOM dates (1989-2002) supplement the FDD tabulations.

Bailey, S. A., I. C. Duggin, C. D. A. vanOverdijk, T. H. JOHENGEN, D. F. REID, and H. J. MacIsaac. Salinity tolerance of diapausing eggs of freshwater zooplankton. Freshwater Biology 49:286-295 (2004).

1. Many freshwater zooplankton produce diapausing eggs capable of withstanding periods of adverse environmental conditions, such as anoxia, drought and extreme temperature. These eggs may also allow oligostenohaline species to survive increased salinity during periods of tidal flux or evaporation, and here we test the ability of diapause eggs to withstand such conditions.
2. Salinity tolerance may also enable organisms to invade new environments. The increased rate of introduction of non-indigenous species to the Laurentian Great Lakes since 1989, when ballast water exchange regulations (to replace fresh/brackish water at sea with full seawater) were first implemented for transoceanic vessels, has stimulated studies that explore mechanisms of introduction, other than of active animals, in ballast water. One hypothesis proposes that freshwater organisms transported in ballast tanks as diapausing eggs may be partially responsible for the increased rate of species introduction, as these eggs may tolerate a wide array of adverse environmental conditions, including exposure to saline water.
3. We collected ballast sediments from transoceanic vessels entering the Great Lakes, isolated diapausing eggs of three species (Bosmina liederi, Daphnia longiremis and Brachionus calyciflorus), and measured the effect of salinity on hatching rate. In general, exposure to salinity significantly reduced the hatching rate of diapausing eggs. However, as nonindigenous species can establish from a small founding population, it is unclear whether salinity exposure will be effective as a management tool.

Bergmann, T., G. L. FAHNENSTIEL, S. E. Lohrenz, D. F. Millie, and O. M. E. Schofield. Impacts of a recurrent resuspension event and variable phytoplankton community composition on remote sensing reflectance. Journal of Geophysical Research 109(C10S15):12 (2004).

In order to characterize the impact of turbidity plumes on optical and biological dynamics, a suite of environmental parameters were measured in southern Lake Michigan during the springtime recurrent sediment plume. In-water measurements of inherent optical properties (IOPs) were entered into the Hydrolight 4.2 radiative transfer model and the output was compared with measured apparent optical properties (AOPs) across a wide range of optical conditions. Hydrolight output and measured underwater light fields were then used to clarify the effects of the sediment plume on primary production, phytoplankton community composition, and nearshore remote sensing ocean color algorithms. Our results show that the sediment plume had a negligible effect on the spectral light environment and phytoplankton physiology. The plume did not significantly alter the spectral quality of available light and did not lead to light limited phytoplankton populations compared to non-plume conditions. Further, the suspended sediment in the plume did not seriously impact the performance of ocean color algorithms. We evaluated several currently employed chlorophyll algorithms and demonstrated that the main factor compromising the efficacy of these algorithms was the composition of phytoplankton populations. As phycobilin-containing algae became the dominant species, chlorophyll algorithms that use traditional blue/green reflectance ratios were compromised due to the high absorption of green light by phycobilin pigments. This is a notable difficulty in coastal areas, which have highly variable phytoplankton composition and are often dominated by sharp fronts of phycobilin and non-phycobilin containing algae.

Bronte, C. R., M. P. Ebener, D. R. Schreiner, D. S. DeVault, M. M. Petzold, D. A. Jensen, C. Richards, and S. J. LOZANO. Fish community change in Lake Superior, 1970-2000. Canadian Journal of Fisheries and Aquatic Sciences 60:1552-1574 (2003).

Changes in Lake Superior’s fish community are reviewed from 1970 to 2000. Lake trout (Salvelinus namaycush) and lake whitefish (Coregonus clupeaformis) stocks have increased substantially and may be approaching ancestral states. Lake herring (Coregonus artedi) have also recovered, but under sporadic recruitment. Contaminant levels have declined and are in equilibrium with inputs, but toxaphene levels are higher than in all other Great Lakes. Sea lamprey (Petromyzon marinus) control, harvest limits, and stocking fostered recoveries of lake trout and allowed establishment of small nonnative salmonine populations. Natural reproduction supports most salmonine populations, therefore further stocking is not required. Nonnative salmonines will likely remain minor components of the fish community. Forage biomass has shifted from exotic rainbow smelt (Osmerus mordax) to native species, and high predation may prevent their recovery. Introductions of exotics have increased and threaten the recovering fish community. Agencies have little influence on the abundance of forage fish or the major predator, siscowet lake trout, and must now focus on habitat protection and enhancement in nearshore areas and prevent additional species introductions to further restoration. Persistence of Lake Superior’s native deepwater species is in contrast to other Great Lakes where restoration will be difficult in the absence of these ecologically important fishes.

Chen, C., L. Wang, J. Qi, H. Liu, J. W. Budd, D. J. SCHWAB, D. BELETSKY, H. A. VANDERPLOEG, B. J. EADIE, T. H. JOHENGEN, J. Cotner, and P. J. Lavrentyev. A modeling study of benthic detritus flux's impacts on heterotrophic processes in Lake Michigan. Journal of Geophysical Research 109(C10S11):13 (2004).

Effects of sediment resuspension-induced benthic detrital flux on the heterotrophic part of the microbial food web in Lake Michigan were examined using a threedimensional (3-D) coupled biological and physical model. The model was driven by the realistic meteorological forcing observed in March 1999. Wind-induced surface wave dynamics were incorporated into the physical model to generate the bottom flux. The model-generated benthic detrital flux was assumed to be proportional to the difference between model-calculated and critical stresses at the bottom. The model results indicate that detrital flux at the bottom was a key factor causing a significant increase of phosphorus and detritus concentrations in the nearshore region of the springtime plume. Inside the plume the sediment-resuspended bottom detritus flux could directly enhance heterotrophic production, while outside the plume, detrital flux from river discharge might have a direct contribution to the high abundance of bacteria and microzooplankton in the nearshore region. Model-data comparison on cross-shore transects near Chicago, Gary, St. Joseph, and Racine suggests that other physical and biological processes may play a comparative role as the bottom detritus flux in terms of the spatial distribution of bacteria and microzoplankton. A more complete microbial food web model needs to be developed to simulate the heterotrophic process in southern Lake Michigan.

Chen, C., L. Wang, R. Ji, J. W. Budd, D. J. SCHWAB, D. BELETSKY, G. L. FAHNENSTIEL, H. A. VANDERPLOEG, B. J. EADIE, and J. Cotner. Impacts of suspended sediment on the ecosystem in Lake Michigan: A comparison between the 1998 and 1999 plume events. Journal of Geophysical Research 109(C10S05):18 (2004).

The impact of a reflective, recurrent coastal resuspension plume on the lower trophic food web system in Lake Michigan was examined using a 3-D coupled physical and biological model. Numerical experiments were conducted for the March 1998 and 1999 plume events. The comparison between modeling results of these 2 years shows that the spatial distributions of the biological fields (i.e., phosphorus, phytoplankton, detritus, etc.) were closely coupled to the physical environment associated with wind-induced threedimensional circulation and mixing. The influence of uspended sediment plumes on the lake ecosystem was reflected in heterotrophic (secondary) production rather than in the autotrophic (primary) production. Nutrients were maintained through nutrient release from suspended sediments within the plume, while it was supplied by current advection and diffusion in the interior. The cross-shore flux of nutrients was driven by episodic wind events with a period of about 5–7 days. The flux was offshore during northerly winds and onshore during southerly winds. Comparisons between energy fluxes among biological variables suggest that the microbial loop (detritus-heterotrophic bacteria and microzooplankton) played an important role in the ecosystem dynamics during plume events. Bacteria were good competitors with phytoplankton for inorganic phosphorus and were also a key supporter for growth of microzooplankton inside and outside the plume. As a result, the lower food web system could be divided into two decoupled loops: (1) detritus-bacteria-microzooplankton-large zooplankton and (2) nutrient-phytoplanktondetritus.

CROLEY, T. E. II. Spatially distributed model of interacting surface and groundwater storage. Proceedings, World Water and Environmental Resources Congress, Salt Lake City, UT, June 27-July 1, 2004. Environmental Water Resources Institute, American Society of Civil Engineers, 10 pp. (2004).

NOAA’s Great Lakes Environmental Research Laboratory (GLERL) developed their Large Basin Runoff Model (LBRM) as a serial and parallel cascade of linear reser-voirs representing moisture storages within a watershed. Each reservoir represents a moisture storage: surface, upper soil zone, lower soil zone, and groundwater zone. GLERL adapted the LBRM from its lumped-parameter definition for an entire water-shed to a two dimensional representation of the flow cells comprising the watershed. This involved changes to the model structure to apply it to the micro scale as well as organization of watershed cells and an implementation of spatial flow routing.

EADIE, B. J., S. A. LUDSIN, D. J. SCHWAB, and J. DePinto. Lake Erie Research Planning Workshop. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, March 4-5, 2004, 28 pp. (2004).

A report from the Presidents Committee on Environmental and Natural Resources on ecological forecasting (CENR, 2001) stressed the nation’s need for developing forecasts of ecological change. To meet this need, NOAA has proposed development of an Ecological Forecasting Service for coastal managers (NOAA, 2003), that would formalize partnerships among all NOAA line offices, universities, and other federal agencies). Both documents identify the widespread societal and economic value that such ecological forecasts could provide to the country, including 1) improved decision-making for coastal stewardship, 2) mitigation of potentially hazardous human activities, 3) reduced impacts of natural hazards, 4) enhanced communication between scientists and managers, and overall, 5) more effective prioritization of science, particularly across disciplines. The long-term goal of these efforts is to produce improved and enhanced ecosystem forecasts (both ecological and environmental) that would benefit coastal communities, including the Great Lakes. Some environmental forecasting already exists (e.g. Great Lakes Forecast System - providing forecasts of lake thermal structure, wind fields, and waves. Enhanced ecosystem forecasts would predict patterns of biological and chemical variables as well as physical and human-induced changes (extreme natural events, climate change, land and resource use, pollution, invasive species, fisheries impacts and interactive effects) to the system across a variety of spatial and temporal scales

Gardner, W. S., P. J. Lavrentyev, J. F. CAVALETTO, M. J. McCarthy, B. J. EADIE, T. H. JOHENGEN, and J. B. Cotner. Distribution and dynamics of nitrogen and microbial plankton in southern Lake Michigan during spring transition 1999-2000. Journal of Geophysical Research 109(C03007):16 pp. (2004).

[1] Ammonium and amino acid fluxes were examined as indicators of N and microbial food web dynamics in southern Lake Michigan during spring. Either 15NH4 + or a mixture of 15N-labelled amino acids (both at 4 mM N final concentration) was added to Lake Michigan water. Net fluxes were measured over 24 h under natural light and dark conditions using deck-top incubators and compared to microbial food web characteristics. Isotope dilution experiments showed similar light and dark NH4 + regeneration rates at lake (6 versus 5 nM N h 1) and river-influenced (20 versus 24 nM N h 1) sites. Ammonium uptake rates were similar to regeneration rates in dark bottles. Dark uptake (attributed mainly to bacteria) accounted for 70% of total uptake (bacteria plus phytoplankton) in the light at most lake sites but only 30% of total uptake at river influenced sites in or near the St. Joseph River mouth (SJRM). Cluster analysis grouped stations having zero, average, or higher than average N-cycling rates. Discriminant analysis indicated that chlorophyll concentration, oligotrich ciliate biomass, and total P concentration could explain 66% of N-cycling rate variation on average. Heterotrophic bacterial N demand was about one third of the NH4 + regeneration rate. Results suggest that, with the exception of SJRM stations, bacterial uptake and protist grazing mediated much of the N dynamics during spring transition. Since NH4 + is more available to bacteria than NO3, regenerated NH4 + may have a strong influence on spring, lake biochemical energetics by enhancing N-poor organic matter degradation in this NO3 -replete ecosystem.

GREAT LAKES ENVIRONMENTAL RESEARCH LABORATORY. Lake level modeling under climate change. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. color brochure (2004).

Global warming is anticipated to have an influence on the water budget of the Great Lakes—the runoff of the drainage basin, direct precipitation onto the lakes, and evaporation from the lake surfaces. Global Climate Models generally show increased precipitation due to global warming, but the warming itself leads to increased evaporation from both land and lake. Whether increased precipitation or increased evaporation dominates determines the net effect on lake water supply and lake levels.There are two different modeling approaches that have been used by GLERL scientists for determining this net effect.

HAWLEY, N. A comparison of suspended sediment concentrations measured by acoustic and optical sensors. Journal of Great Lakes Research 30(2):301-309 (2004).

Simultaneous acoustic and optical measurements of suspended sediment concentration were made during five deployments in southern Lake Michigan. The sensors gave similar results when bottom resuspension was the main cause of changes in suspended sediment concentration, but during the stratified period, when a nepheloid layer was present and large-scale zooplankton movement occurred, the sensors gave quite different results. Since the two types of sensors are most sensitive to particles of different sizes, the simultaneous deployment of acoustic and optical sensors may allow the response of different sized particles to similar forcings to be identified. Care, however, must be taken when comparing suspended sediment concentrations derived from optical and acoustic observations.

HAWLEY, N. Response of the benthic nepheloid layer to near-inertial waves in southern Lake Michigan. Journal of Geophysical Research 109(C04007):14 (2004).

Time series measurements of water transparency, water temperature, and current velocity were made at a station located in 58 m of water in southern Lake Michigan during the summer of 1995. Currents generated by near-inertial internal waves are correlated with variations in the thickness and in the vertical distribution of suspended sediment in the benthic nepheloid layer. Although a direct causal link between internal wave action and changes in the nepheloid layer could not be established, the data suggest that local resuspension by shoaling internal waves maintains the layer during the stratified period. The origin and maintenance of the benthic nepheloid layer is most likely the result of local resuspension due to a combination of internal wave action and longer-term processes.

HAWLEY, N., B. M. Lesht, and D. J. SCHWAB. A comparison of observed and modeled surface waves in southern Lake Michigan and the implications for models of sediment resuspension. Journal of Geophysical Research 109(C10S03):11 (2004).

Subsurface pressure sensors were used to make measurements of surface waves during 18 deployments in southern Lake Michigan between 1998 and 2000. Most of the observations were made during the unstratified period (November–May) in water depths between 10 and 55 m. The observations (as well as those obtained from the National Data Buoy Center (NDBC) buoy 45007, which is located in the middle of the southern basin of the lake) were compared to the results obtained from the Great Lakes Environmental Research Laboratory (GLERL)-Donelan wave model implemented on a 2-km grid. The results show that the wave model does a good job of calculating the wave heights, but consistently underestimates the wave periods. In over 80% of the cases the bottom stresses calculated from both the observations and the wave model results agree as to whether or not resuspension occurs, but over 70% of this agreement is for cases when resuspension does not occur; both stresses predict resuspension about 6% of the time. Since the bottom stresses calculated from the model results are usually lower than those calculated from the observations, resuspension estimates based on the wave model parameters are also lower than those calculated from the observed waves.

Hedges, K. J., S. A. LUDSIN, and B. J. Fryer. Effects of ethanol preservation on otolith microchemistry. Journal of Fish Biology 64:923-937 (2004).

Solution-based inductively coupled plasma-mass spectrometry was used to examine the effects of exposure time to ethanol (0, 1, 3, 9, 27 and 81 days) and ethanol quality (ACS- v. HPLC grade) on strontium (Sr) and barium (Ba) concentrations in sagittal otoliths of hatchery-raised and wild-caught young-of-the-year walleye Stizostedion vitreum. No effect of either attribute on Sr and Ba concentrations were detected, indicating that metabolically inert elements that replace calcium in the calcium carbonate matrix (e.g. Sr and Ba) are not influenced by storage in 95% ethanol.

Holcombe, T. L., L. L. Taylor, D. F. REID, J. S. Warren, P. A. VINCENT, and C. E. Herdendorf. Revised Lake Erie postglacial lake level history based on new detailed bathymetry. Journal of Great Lakes Research 29(4):681-704 (2003).

Holocene lake level history and paleogeography of Lake Erie are re-interpreted with theaid of new bathymetry, existing water budget data, and published information. Morphology and elevation of present and former shoreline features (sand ridges, forelands, spits, bars, and fans) record the waterlevel at which they were formed. Of eighteen such features observed in Lake Erie, six occur nearshore and were formed at or near present lake level, and twelve features apparently formed at lower lake levels. It seems likely that lake level fell below the level of the outlet sill during the 9-6 ka climate optimum, when warmer and drier conditions prevailed. During such times lake level likely rose and fell as controlled by the water budget, within a window of constraint imposed by increases and decreases in evaporation, which would have varied directly with lake surface area. Near Buffalo, possible shoreline features occurring 3-6 km offshore at depths of 9-12 m could have formed at lower lake levels. Annual water volumes in each term of the water budget, (runoff, precipitation, and evaporation) are large relative to the volumetric capacity of Lake Erie itself. Such events as introduction of even a modest amount of upper Great Lakes water, or the onset of cooler and less dry climate conditions, could cause significant, rapid, lake level rise. Schematic reconstructions illustrate changing paleogeography and a Holocene lake level history which has varied with: blocking! unblocking of outlet sills; erosion of outlet sills; distance from outlet sills; differential isostatic rebound; upper Great Lakes drainage flowing into or bypassing the lake;and climate-driven water budget of the Lake Erie drainage basin.

Hornbuckle, K. C., G. L. Smith, S. M. Miller, B. J. EADIE, and M. B. LANSING. Magnitude and origin of polychlorinated biphenyl (PCB) and dichlorodiphenyltrichloroethane (DDT) compounds resuspended in southern Lake Michigan. Journal of Geophysical Research 109(C05017):10 (2004).

Polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) compounds are introduced into the water as a result of large-scale storms and sediment resuspension in the southern basin of Lake Michigan. Settling and suspended sediments, as well as air and water samples, were collected in southern Lake Michigan over a 12 month period. Analysis of contaminant fluxes on settling particles shows that approximately 370 kg of PCBs and 110 kg of DDT compounds are resuspended in southern Lake Michigan during a single basin-wide event (January 1999). Examination of contaminant signals indicates strong regional and temporal source-receptor relationships between settling, suspended, and surficial sediments. The settling, suspended, and bottom surficial sediments in the shallow waters of the southern coastal region are enriched in lower molecular weight PCBs. The sediments in the water column and on the lake bottom in the deeper regions are enriched in higher molecular weight PCBs. Furthermore, falling sediments collected in the deeper regions of the lake are enriched in 4,40-DDT. The unique contaminant signal in deep water regions is surprising and suggests a source/receptor relationship among the bottom sediments and the sediments suspended and settling above them.

Hook, T. O., E. S. Rutherford, S. J. Brines, D. J. SCHWAB, and M. J. McCORMICK. Relationship between surface water temperature and Steelhead distributions in Lake Michigan. North American Journal of Fisheries Management 24:211-221 (2004).

Salmonines support valuable recreational fisheries and are the predominant predatorsin the open waters of the Great Lakes, yet the spatial distributions of salmonines in these systemshave not been fully documented. We analyzed the horizontal distributions of steelhead Oncocrhynchus mykiss in Lake Michigan from 1992 to 1997 and related these distributions to mean surface temperature and temperature variation. We used angler catch rate data from Lake Michigan natural resources agencies to index the spatial and temporal distributions of steelhead and obtained surface water temperature data from advanced very-high-resolution radiometer satellite imagery through the National Oceanic and Atmospheric Administration's CoastWatch Program. During most months, steelhead catch rates were negatively related to surface temperature and were highest in areas of high temperature variation (i.e., vertical thermal fronts and upwelling zones) where thermal conditions and prey densities may have been optimal for growth. Our results demonstratehow remotely sensed and creel survey data can be integrated to allow for more effective exploitation and management of lakewide fish stocks while enabling researchers to generate and test hypotheses regarding the spatial distributions of fish populations.

Hwang, H., S. W. Fisher, K. Kim, and P. F. LANDRUM. Comparison of the toxicity using body residues of DDE and select PCB congeners to the midge Chironomus riparius, in partial-life cycle tests. Archives of Environmental Contamination and Toxicology 46:32-42 (2004).

Due to the long time course required to achieve steady state with highly lipophilic contaminants such as PCBs (polychlorinated biphenyls), data derived from short-term toxicity tests may lead to an erroneous interpretation of hazard. In addition, PCBs bioaccumulated over time can cause sublethal impairments in organisms at concentrations much lower than required for mortality. Here, the body residues of 1,1 -dichloro-2,2-bis-p-chlorophenyl ethane (DDE) and select PCB congeners associated with a spectrum of chronic effects in the midge, Chironomus riparius, were evaluated. The route of exposure was ingestion of the PCB-contaminated alga, Chiorella vulgarus, and trout chow loaded with the selected test compound. Two separate exposures of midges were performed. In the first experiment, midges were exposed from the second instar to the pupal stage. In the second exposure, midges were exposed from the second instar to the adult stage. A variety of sublethal endpoints was monitored, including developmental time within a stadium, body weight, and fecundity for the female adult. The dose was assessed as the whole body residue concentration of the contaminant. Overall, the midge concentration increased with increasing exposure concentration in algae and trout chow. Body weight at the end of each stadium was the assessment parameter that was least significantly affected among the test endpoints monitored. In contrast, a significant increase in development time was the endpoint that was most frequently observed in response to contaminant exposure. Reduction in fecundity was found only for DDE-exposed midges. These data, in which chronic endpoints are related to body residues, suggest that body residues will be useful in defining sublethal hazards of DDE and some PCB congeners.

Kerfoot, W. C., J. W. Budd, B. J. EADIE, H. A. VANDERPLOEG, and M. AGY. Winter storms: sequential sediment traps record Daphnia ephippial production, resuspension, and sediment interactions. Limnology and Oceanography 49(4, part 2):1365-1381 (2004).

For species that do not over-winter, an essential part of the life cycle is the production of diapausing eggs. We use sequential sediment traps in southern Lake Michigan (1997–2000) to capture settling Daphnia ephippia and sediments, characterizing ephippial production and sediment interactions during hazardous conditions. Each year, there was an enormous pulse of D. mendotae ephippia (ca. 7.2 3 1013 ephippia, 1.2 3 1014 diapausing eggs) that coincided with autumn population decline. Most ephippia settled through the water column, although a few were captured at the water surface and blown shoreward. The duration and amplitude of the autumn ephippial fluxes were similar among years. Ephippial production was positively correlated with water column depth, a consequence of Daphnia spatial abundance. In contrast, resuspension of ephippia was inversely related to water column depth and spatially complex, influenced by waves, coastal currents, and offshore gyre circulation. Large winter storms created nearshore sediment plumes, could resuspend vast numbers of ephippia (e.g., 10 March 1998 storm; 1.9 3 1012 ephippia and 3.1 3 1012 diapausing eggs), and were important in the formation of ‘‘egg banks.’’ Almost all newly produced and resuspended diapausing eggs came from D. mendotae, with very few from two other species (D. retrocurva, D. dentifera) that dominated waters 12 yr ago. These observations suggest a relatively short relaxation time for species cycling out of egg banks in Lake Michigan (10 yr), due in part to (1) differential resuspension of unconsolidated versus consolidated sediments and (2) the spatially restricted nature of ‘‘high-sedimentation’’ zones. Our study is the first use of sequential sediment traps to document diapause egg production.

Krause, A. E., K. A. FRANK, D. M. MASON, R. E. Ulanowicz, and W. W. Taylor. Compartments revealed in food-web structure. Nature 426:282-285 (2003).

Compartments in food webs are subgroups of taxa in which many strong interactions occur within the subgroups and few weak interactions occur between the subgroups. Theoretically, compartments increase the stability in networks1–5, such as food webs. Compartments have been difficult to detect in empirical food webs because of incompatible approaches or insufficient methodological rigour. Here we show that a method for detecting compartments from the social networking science identified significant compartments in three of five complex, empirical food webs. Detection of compartments was influenced by food web resolution, such as interactions with weights. Because the method identifies compartmental boundaries in which interactions are concentrated, it is compatible with the definition of compartments. The method is rigorous because it maximizes an explicit function, identifies the number of nonoverlapping compartments, assigns membership to compartments, and tests the statistical significance of the results. A graphical presentation reveals systemic relationships and taxaspecific positions as structured by compartments. From this graphic, we explore two scenarios of disturbance to develop a hypothesis for testing how compartmentalized interactions increase stability in food webs.

Kukkonen, J., P. F. LANDRUM, S. Mitra, D. C. GOSSIAUX, J. Gunnarson, and D. Weston. The role of desorption for describing the bioavailability of select PAH and PCB congeners for seven laboratory-spiked sediments. Environmental Toxicology and Chemistry 23(8):1842-1851 (2004).

Lumbriculus variegatus and Diporeia spp. were exposed to two contaminant pairs 3H-benzo[a]pyrene (BaP) and 14C-2,4,5,2949,59-hexachlorobiphenyl (HCBP), and 3H-pyrene (PY) and 14C-3,4,39,49-tetrachlorobiphenyl (TCBP) sorbed to each of seven field-collected sediments of varying composition. Toxicokinetic coefficients, bioaccumulation factors (BAF), and biota-sediment accumulation factors ([BSAF], BAF normalized to the organism lipid content and sediment organic carbon content) were determined. The contaminant desorption rates from sediments were measured with a Tenax resin extraction technique. The desorption rate constants for rapid, slow, and very slow contaminant compartments and the fractions of contaminant in each compartment were compared with the toxicokinetic coefficients, BAF, and BSAF to describe contaminant behavior across sediments, among compounds, and between species. The best description of the bioavailability was the log BSAF regressed against the fraction rapidly desorbed (Frapid) across all sediments and compounds for both species, r2 5 0.67 and 0.66 for L. variegatus and Diporeia, respectively. Use of a calculated fraction desorbed in 6 h or 24 h, which has been suggested as a surrogate for Frapid, did not produce as predictive a regression because of uneven desorption in a fixed duration for each compound among the sediments. Thus, Frapid provided a good surrogate for the bioavailability of the sediment-sorbed contaminant as represented by BSAF across seven sediments and four compounds with predictions within a factor of approximately two of the measured value.

Kukkonen, J. V. K., P. F. LANDRUM, S. Mitra, D. C. GOSSIAUX, J. Gunnarson, and D. Weston. Sediment characteristics affecting the desorption kinetics of select PAH and PCB congeners for seven laboratory-spiked sediments. Environmental Science and Technology 37:4656-4663 (2003).

Measures of desorption are currently considered important as potential surrogates for bioaccumulation as measures of the bioavailability of sediment-sorbed contaminants. This study determined desorption rates of four laboratory spiked compounds, benzo[ a]pyrene (BaP), 2,4,5,2',4',5'- hexachlorobiphenyl (HCBP), 3,4,3',4'-tetrachlorobiphenyl (TCBP), and pyrene (PY), to evaluate the effect of sediment characteristics. The compounds were sorbed onto seven sediments with a broad range of characteristics. Desorption was measured by Tenax-TA extraction from aqueous sediment suspensions. Desorption rates were modeled using an empirical three compartment model describing operationally defined rapid, slow, and very slow compartments. The sediments were characterized for plant pigments, organic carbon (OC), total nitrogen (TN), lipids, NaOH extractable residue, lignin, amino acids, soot carbon, andparticle size fractions. Desorption from the rapid compartment for each of the planar compounds BaP, PY, and TCBP was significantly correlated to sediment characteristics that could be considered to represent younger (i.e., less diagenetically altered) organic matter, e.g., plant pigment, lipid, and lignin contents. However, for these compounds there were no significant correlations between desorption and OC, TN, soot carbon, or amino acid contents. HCBP desorption was different from the three planar molecules. For HCBP, the flux from the rapid compartment was negatively correlated (0.1 > p> 0.05) with the OC content of the sediment. Overall, HCBP desorption was dominated by the amount of OC and the particle size distribution of the sediments, while desorption of the planar compounds was dominated more by the compositional aspects of the organic matter.

LANDRUM, P. F., M. Leppanen, S. D. ROBINSON, D. C. GOSSIAUX, G. A. Burton, M. Greenburg, J. V. K. Kukkonen, B. J. EADIE, and M. B. LANSING. Effect of 3,4,3',4'-tetrachlorobiphenyl on the reworking behavior of Lumbriculus variegatus exposed to contaminated sediment. Environmental Toxicology and Chemistry 23(1):178-186 (2004).

The reworking response (bioturbation) of the oligochaete Lumbriculus variegatus was measured by following the burialrate and spread of a 137Cs marker layer translating worm activity into a biological burial rate (Wb) and a biological diffusion rate constant (Db) for surficial sediment mixing. Reworking was measured at 10 and 22°C in two sediments: a reference site sediment dosed with 3,4,3',4'-tetrachlorobiphenyl (TCBP) and a field-collected sediment from a polychlorinated biphenyl (PCB)-contaminated site in Dicks Creek (DCC, Middletown, OH, USA). The body residue associated with response to TCBP also was determined. Reduction in the temperature from 22 to 10°C reduced both W5 and Dh by a factor of approximately two. The internal TCBP concentration to reduce the Wh by 50% was 96 nmol/g (95% CI 45-225 nmol/g) and 124 nmollg (40-547 nmol/g) (28 and 36 pg/g) wet weight at 22 and 10°C, respectively, and was independent of temperature. The Wb for the DCC sediment was lower than observed for the highest TCBP treatment. The internal body residue for total PCB for worms exposed to DCC sediment was 20-fold lower than TCBP in worms exposed to the lowest TCBP treatment on a molar basis. Comparing body residues of total PCB to TCBP assumes that the PCB congeners act additively on a molar basis. The DCC site contained a higher proportion of coarse material and a lower organic carbon concentration. The difference in sediment characteristics was assumed to be responsible for differences in the Wb.

LANDRUM, P. F., J. A. Steevens, D. C. GOSSIAUX, M. McELROY, S. ROBINSON, L. Begnoche, S. Chernyak, and J. Hickey. Time-dependent lethal body residues for the toxicity of pentachlorobenzene to Hyalella azteca. Environmental Toxicology and Chemistry 23(5):1335-1343 (2004).

The study examined the temporal response of Hyalella azteca to pentachlorobenzene (PCBZ) in water-only exposures. Toxicity was evaluated by calculating the body residue of PCBZ associated with survival. The concentration of PCBZ in the tissues of H. azteca associated with 50% mortality decreased from 3 to 0.5 umol/g over the temporal range of 1 to 28 d, respectively. No significant difference was observed in the body residue calculated for 50% mortality when the value was determined using live or dead organisms. Metabolism of PCBZ was not responsible for the temporal response because no detectable PCBZ biotransformation occurred over an exposure period of 10 d. A damage assessment model was used to evaluate the impact and repair of damage by PCBZ on H. azteca. The toxicokinetics were determined so that the temporal toxicity data could be fit to a damage assessment model. The half-life calculated for the elimination of PCBZ averaged approximately 49 h, while the value determined for the half-life of damage repair from the damage assessment model was 33 h.

LANDRUM, P. F., M. Leppanen, S. D. ROBINSON, D. C. GOSSIAUX, G. A. Burton, M. Greenberg, J. V. K. Kukkonen, B. J. EADIE, and M. B. LANSING. Comparing behavioral and chronic endpoints to evaluate the response of Lumbriculus variegatus to 3,4,3',4',-terachlorobiphenyl sediment exposures. Environmental Toxicology and Chemistry 23(1):187-194 (2004).

The response of Lumbriculus variegatus to 3,4,3',4-tetrachlorohiphenyl (TCBP) was examined with feeding behavior and changes in carbon assimilation by using stable carbon isotopes at 22 and 10°C. The classical measure of feeding behavior determined on a subset of sediment for which the biological burial rate was determined in a companion study allowed direct method comparison. This comparison helped address relationships between biological burial rate, feeding rate, and bioaccumulation. The change in stable isotope composition reflects the total metabolic activity by measuring carbon assimilation rate and was compared to feeding rate, biological burial rate (as determined in the companion study), and reproduction. Decreasing the temperature from 22 to 10°C resulted in a twofold reduction in feeding rate and carbon assimilation. The fractional decline in feeding rate relativeto the control mimicked the decline in the biological burial rate with increasing TCBP concentration that was found in the companion study. The bioaccumulation factor declined with increasing TCBP sediment concentration, tracking the feeding rate decline. Stable isotope measures showed differences in metabolic rates between the exposure temperatures but did not distinguish a metabolic ratechange at 22°C among TCBP treatments. Likewise, reproduction declined from 22 to 10°C, with no reproduction at 10°C. Like the stable isotope measure, no dose response was found among TCBP treatments at 22°C. The reduction in carbon assimilation ratetracked the reduction in reproduction with lower temperature.

Leppanen, M. T., P. F. LANDRUM, J. V. K. Kukkonen, M. S. Greenerg, G. A. Burton Jr., S. D. ROBINSON, and D. C. GOSSIAUX. Investigating the role of desorption on the bioavailability of sediment-associated 3,4,3',4'-tetrachlorobiphenyl in benthic invertebrates. Environmental Toxicology and Chemistry 22(12):2861-2871 (2003).

Only a fraction of all sediment-associated hydrophobic organic contaminants are bioavailable, and a simple Tenax® extraction procedure may estimate this fraction. Bioavailability is assumed to coincide with the rapidly and, possibly, slowly desorbing sediment-associated contaminant. River sediment was spiked with radiolabeled ('4C) and nonradiolabeled ('2C) 3,4,3',4'-tetraehlorobiphenyl (TCBP), and desorption kinetics using Tenax extraction were obtained at 10°C and 22°C. Bioaccumulation was measured in Lumbriculus variegatus, Chironomus tentans, and Hyalella azteca. Desorption of TCBP was triphasic at 22°C and slowed at 10°C to show only biphasic kinetics. The rapidly desorbing fractions decreased with increasing TCBP sediment concentration. The biota sediment accumulation factors, biota accumulation factors, and sediment clearance coefficients (ks) also decreased with increasing sediment TCBP concentration. The rapidly plus slowly desorhing fractions and the total TCBP desorbed when 99.9% of the rapidly desorbing fraction had desorbed were used to estimate bioavailable TCBP. These Tenax-based fractions didnot explain the decreasing bioavailability with increasing TCBP load. Several factors, such as animal behavior and TCBP water solubility limitations, were evaluated to explain the concentration effect, but the most likely cause was severe diffusion limitations in whole sediment that were not predicted by the fully mixed Tenax extraction. Therefore, desorbing fractions determined by Tenax extraction overestimated the bioavailable fractions in sediments.

LESHKEVICH, G. A., and S. V. Nghiem. Recent anomalies in Great Lakes ice cover based on statistical analysis and observation. 2004 IEEE International Geoscience and Remote Sensing Symposium, Anchorage, AK, September 20-24, 2004. IEEE, 1 pp. (2004).

The Laurentian Great Lakes, the world's largest freshwater surface with a drainage basin extending 1110 km north-south and 1390 km east-west, have a combined surface area of about 245,000 km2, a combined volume of approximately 22,800 km2, and contribute significantly to economic and social activities of North America. The Great Lakes region provides 20% of the United States gross national product and is where one in eight Americans live. Ice cover in the Great Lakes, the most obvious seasonal transformation in the physical characteristics of the lakes, has a major impact on the regional climate, local commerce, and public safety. Lake ice is a sensitive index of regional winter climate.

LIU, P. C., and U. F. Pinho. Freak Waves -- More frequent than rare! Annales Geophysicae 22:1839-1842 (2004).

Contrary to the widely held notion that considers the occurrence of freak waves in the ocean as being rare, from an examination of five years of wave measurements made in the South Atlantic Ocean, we found the occurrence of freak waves is actually more frequent than rare.

LOFGREN, B. M. Global warming effects on Great Lakes water: More precipitation but less water? Proceedings, 18th Conference on Hydrology, 84th Annual Meeting of the American Meteorological Society, Seattle, WA, January 11-15, 2004. American Meteorological Society, 3 pp. (2004).

The question of the net effect of global warming, and of other changes in climate on water resources can often be more complex than is indicated by individual simple measures. The dimensions of total precipitation, evapotranspiration, soil moisture, runoff, and net basin supply can interact in ways that are not related at a simple intuitive level. Different methodologies of modeling these variables can yield different results. But some simple conservation laws can help in creating a qualitative sense of how the water cycle of continents and oceans are constrained, how this is likely to change with increased greenhouse gas concentrations, and how this might play out in the case of the water supply of the Laurentian Great Lakes. Some simple conservation laws will be presented in qualitative form in section 2. Section 3 will summarize some contrasting results derived from different methods for determining the effect of global warming on Great Lakes net basin supply and water levels. Relations will be drawn using the simple conservation laws to help explain the different results that come of using different methodologies.

LOZANO, S. J., and T. F. NALEPA. Disruption of the benthic community in Lake Ontario. In State of Lake Ontario (SOLO) - Past, Present, and Future. M. M. (Ed.). Aquatic Ecosystem Health and Management Society, 305-322 (2003).

The benthic macroinvertebrate community of the Great Lakes is dominated by a few species of organisms. The cold-stenotherm association includes Oligochaeta, Sphaeriidae, and Diporeia spp. (Cook and Johnson, 1974), an association that reflects an oligotrophic condition. In general, total abundance of invertebrates declines with depth and distance from shore (Nalepa and Thomas, 1976). Two species of oligochaetes, Stylodrilus heringianus and Limnodrilus hoffmeisteri, are found throughout the offshore regions and may account for 10-20% of the total benthic population density (Mozley and Howmiller, 1977). Members of the bivalve family Sphaeriidae are usually found in waters less than 90 meters and account for 5-15% of the total benthic population density. The amphipod, Diporeia spp. (formerly Pontoporeia hoyi), is the most abundant macroinvertebrate (Mozley and Howmiller, 1977; Nalepa, 1991) in the Great Lakes. In deeper water habitats, it accounts for 40-70% of the total density of benthic organisms below the summer thermocline (Nalepa, 1991), reaching greatest densities at depths of 30 to 60 m.

Marvin, C., S. Painter, D. Williams, V. Richardson, R. Rossmann, and P. L. VAN HOOF. Spatial and temporal trends in surface water and sediment contamination in the Laurentian Great Lakes. Environmental Pollution 129:131-144 (2004).

Data from recent sediment and surface water surveys have been collated and mapped to illustrate the spatial distribution of contaminants across the entire Great Lakes basin. Information from historical surveys, together with data from surface water monitoring programs in three major connecting channels, has also been collated in order to evaluate temporal trends. In general, Lakes Superior and Michigan exhibited the lowest levels of sediment contamination while Lake Ontario had the highest. Contaminants such as y-HCH (lindane) and dieldrin were ubiquitous in surface waters across the entire basin, which was indicative of atmospheric sources. The distribution of other compounds including hexachlorobenzene, octachlorostyrene and mirex indicated the presence of local sources within the watersheds of the connecting channels. Surficial sediment contamination was found to have decreased markedly since the late 1960s and 1970s. Similarly, surface water contamination decreased over the period 1986-1997 with concentrations of dieldrin, hexachlorobenzene, octachlorostyrene and mirex reduced by over 50%. However, the spatial distributions of both sediment and surface water contamination indicate that further effort is warranted in reducing local sources of contaminants, particularly in Lake Ontario.

McCarty, H. B., J. Schofield, K. Miller, R. N. Brent, P. L. VAN HOOF, and B. J. EADIE. Results of the Lake Michigan Mass Balance Study: Polychlorinated biphenyls and trans-nonachlor data report. EPA 905 R-01-011. U.S. EPA Great Lakes National Program Office, Chicago, IL 60604, 300 pp. (2004).

The U.S. Environmental Protection Agency’s Great Lakes National Program Office (GLNPO) and its partners instituted the Lake Michigan Mass Balance (LMMB) Study to measure and model the concentrations of representative pollutants within important compartments of the Lake Michigan ecosystem. The goal of the LMMB Study was to develop a sound, scientific base of information to guide future toxic load reduction efforts at the Federal, State, Tribal, and local levels. Objectives of the study were to: 1. Estimate pollutant loading rates, 2. Establish a baseline to gauge future progress, 3. Predict the benefits associated with load reductions, and 4. Further understand ecosystem dynamics. The LMMB Study measured the concentrations of mercury, polychlorinated biphenyls (PCBs), transnonachlor, and atrazine in the atmosphere, tributaries, lake water, sediments, and food webs of Lake Michigan. This document summarizes the PCB and trans-nonachlor data collected as part of the LMMB Study, and is one in a series of data reports that documents the project.

McGeehin, J., G. S. burr, G. Hodgins, S. J. Bennett, J. A. ROBBINS, N. R. MOREHEAD, and H. Markewich. Stepped-combustion 14C dating of bomb carbon in lake sediment. Radiocarbon 46(2):893-900 (2004).

In this study, we applied a stepped-combustion approach to dating post-bomb lake sediment from north-central Mississippi. Samples were combusted at a low temperature (400 °C) and then at 900 °C. The CO, was collected separately for both combustions and analyzed. The goal of this work was to develop a methodology to improve the accuracy of 14C dating of sediment by combusting at a lower temperature and reducing the amount of reworked carbon bound to clay minerals in the sample material. The 4C fraction modem results for the low and high temperature fractions of these sediments were compared with well-defined '37Cs determinations made on sediment taken from the same cores. Comparison of "bomb curves" for '4C and '37Cs indicate that low temperature combustion of sediment improved the accuracy of 4C dating of the sediment. However, fraction modem results for the low temperature fractions were depressed compared to atmospheric values for the same time frame, possibly the result of carbon mixing and the low sedimentation rate in the lake system.

Messick, G. A., H. A. VANDERPLOEG, J. F. CAVALETTO, and S. S. Tyler. Histological characteristics of abnormal protrusions on copepods from Lake Michigan. Zoological Studies 43(2):314-322 (2004).

Abnormal protrusions have been observed on crustacean zooplankton species from Lake Michigan since 1994. Copepods collected from 1994 to 2000 were assayed for the prevalence of protrusions, and histologically characterized for various morphologies. Protrusions occurred more frequently on nauplii than on copepodites or adults. Most protrusions were located laterally on the copepod body. External shapes and surfaces of the protrusions varied from smoothly rounded to bossulated and amorphous. Protrusions had diverse histological characteristics. Necrotic tissue was present in 58% of protrusions. Some protrusions had hyaline, crystal-like structures either on the surface or embedded within tissues of the protrusion. Nearly 40% contained what appeared to be herniated host tissue. A few copepods (3%) had elongated, symmetrical, somewhat transparent gross protrusions that were histologically identified as ellobiopsid parasites. Other protrusions had a histology that suggested ellobiopsid parasites such as a bossulated, bud-like external morphology or a smoothly rounded covering. Additionally, round structures observed within protrusions were similar to sporulation bodies of ellobiopsid parasites. It is unlikely that these protrusions were due to fixation artifacts or were caused by diatoms puncturing copepods in the collection devices. A few protrusions were obvious ellobiopsid parasites, but the histology of most protrusions is not consistent or obvious enough to allow identification of a plausible etiological agent.

Messick, G. A., R. M. Overstreet, T. F. NALEPA, and S. Tyler. Prevalence of parasites in amphipods Diporeia spp. from Lakes Michigan and Huron, USA. Diseases of Aquatic Organisms 59:159-170 (2004).

Amphipods of Diporeia spp. have declined considerably during the last decade in the Great Lakes. We examined the possibility that disease may be affecting these populations. A histological survey assessed the parasites in species of Diporeia within Lakes Huron and Michigan, USA, and the host response to some of them and to unknown factors. Amphipods were found to have an intranuclear inclusion body, and were hosts to a rickettsia-like organism, fungi, a haplosporidian, a microsporidian, epibiotic ciliates, a gregarine, a cestode, acanthocephalans and nodule formations. Epibiotic ciliates were most common (37% prevalence of infection), but a microsporidian (3.8%), a rickettsia-like organism (1.6%), fungi, including a yeast-like organism (1.3%), worms (1.3%), and a haplosporidian (0.7%) are likely associated with mortalities or detrimental effects on the host. The role these agents may have played in the decline of Diporeia spp. in the Great Lakes over the last decade is not clear. Interrelationships with the dynamics of various physical and biological factors such as high sedimentation, diminished food supplies, and virulent parasites could synergistically cause the decline in Diporeia spp. populations in Lakes Michigan and Huron.

MILLER, G. S. Mysis vertical migration in Grand Traverse Bay, Lake Michigan, observed by an Acoustic Doppler Current Profiler. Journal of Great Lakes Research 29(3):427-435 (2003).

The acoustic return signal from Acoustic Doppler Current Profilers (ADCP) moored in Traverse Bay during a 90-day summer period showed a rapid 5-10 dB increase about 1/2 hour after sun-set and a similar decrease 1/2 hour before sunrise. The pattern is characteristic of zooplankton die! vertical migration, most likely Mysis relicta. These are the first reported observations of freshwater invert-ibrate migrations using ADCP backscatter. A 15-20 m thick sound scattering layer also persistedthroughout the summer. This layer, constrained between the 6°C and 10°C isotherms, generally followedthe internal thermocline fluctuations. These backscatter data demonstrate that determining characteristics of diel migration, and monitoring zooplankton temporal and spatial variability are possible using ADCPs.

Millie, D. F., G. L. FAHNENSTIEL, S. E. Lohrenz, H. J. Carrick, T. H. JOHENGEN, and O. M. E. Schofield. Physical-biological coupling in southern Lake Michigan: Influence of episodic sediment resuspension on phytoplankton. Aquatic Ecology 37:393-408 (2003).

The influence of episodic, sediment resuspension on phytoplankton abundance/volume and composition, the photosynthetic maximum rate (PBmax) and efficiency (aB), and chlorophyll-specific growth (uChl) was evaluated during the spring isothermal period in southern Lake Michigan (Laurentian Great Lakes, USA). Resuspension altered the nutrient and light climate of nearshore waters; light attenuation (Kd) and phosphorus concentrations corresponded (p <- 0.0001 and p <- 0.001, respectively) with concentrations of suspended particulate matter SPM. Phytoplankton cell volume and diatom cell abundance and volume were not associated with SPM concentrations (p > 0.05). Diatom composition displayed spatial dissimilarities corresponding with resuspension (p <- 0.001); small centric diatoms exhibiting meroplanktonic life histories and pennate diatoms considered benthic in origin were most abundant within SPM-impacted, nearshore waters whereas taxa typically comprising assemblages in optically-clear, offshore waters and the basin-wide, spring bloom were not. Values of PBmax and aB corresponded (p <- 0.0001) with both Kd coefficients and SPM concentrations, potentially reflecting increased light harvesting/utilization within impacted assemblages. However, integral production was inversely associated with Kd coefficients and SPM concentrations (p < 0.0001) and photosynthesis was light-limited or nearly so for most assemblages. Although uChl values corresponded with Kd coefficients (p <- 0.05), values were quite low (x¯ +- S.E., 0.10 +- 0.004 d–1) throughout the study. Most likely, distinct rate processes between SPM- and nonimpacted assemblages reflected short-term compositional and corresponding physiological variations due to infusion of meroplankton and/or tributary-derived phytoplankton. Overall, resuspension appears to have little, if any, long-term impact upon the structure and function of the lake’s phytoplankton.

Neilson, M. A., D. S. Painter, G. Warren, R. A. Hites, I. Basu, D. V. C. Weseloh, D. M. Whittle, G. Christie, R. Barbiero, M. Tuchman, O. E. Johannsson, T. F. NALEPA, T. A. Edsall, G. Fleischer, C. Bronte, S. B. Smith, and P. C. Baumann. Ecological monitoring for assessing the state of the nearshore and open waters of the Great Lakes. Environmental Monitoring and Assessment 88:103-117 (2003).

The Great Lakes Water Quality Agreement stipulates that the Governments of Canada and the United States are responsible for restoring and maintaining the chemical, physical, and biological integrity of the waters of the Great Lakes Bain Ecosystem. Due to varying mandates and areas of expertise, monitoring to assess progress towards this objective is conducted by a multitude of Canadian and U.S. federal and provincial/state agencies, in cooperation with academia and regional authorities. This paper highlights selected long-term monitoring programs and discusses a number of documented ecological changes that indicate the present state of the open and nearshore waters of the Great Lakes.

Nghiem, S. V., G. A. LESHKEVICH, and B. W. Stiles. Wind fields over the Great Lakes measured by the SeaWinds scatterometer on the QuikSCAT satellite. Journal of Great Lakes Research 30(1):148-165 (2004).

This paper demonstrates the utility of satellite scatterometer measurements for wind retrieval over the Great Lakes on a daily basis. We use data acquired by the Sea Winds Scatterometer on the QuikSCAT (QSCAT) satellite launched in June 1999 to derive wind speeds and directions over the lakes at a resolution of 12.5 km, which is two times finer than the QSCAT standard ocean wind product at a resolution of 25 km. To evaluate QSCAT performance for high-resolution measurements of lake wind vectors, we compare QSCAT results with Great Lakes Coastal Forecasting System (GLCFS) nowcast wind fields and with standard QSCAT measurements of ocean wind vectors. Although the satellite results over the Great Lakes are obtained with an ocean model function, QSCAT and GLCFS wind fields compare well together for low to moderate wind conditions (4-32 knots). For wind speed, the analysis shows a correlation coefficient of 0.71, a bias of 2.6 knots in mean wind speed difference (nowcast wind is lower) with a root-mean-square (rms) deviation of 3.8 knots. For wind direction, the correlation coefficient is 0.94 with a very small value of 1.3° in mean wind direction bias and an rms deviation of 38° for all wind conditions. When excluding the low wind range of 4-12 knots, the rms deviation in wind direction reduces to 22°. Considering QSCAT requirements designed for ocean wind measurements and actual evaluations of QSCA Tperformance over ocean, results for high-resolution lake wind vectors indicate that QSCA T performs well over the Great Lakes. Moreover, we show that wind fields derived from satellite scatterometer data before, during, and after a large storm in October 1999, with winds stronger than 50 knots, can monitor the storm development over large scales. The satellite results for storm monitoring are consistent with GLCFS nowcast winds and lake buoy measurements. A geophysical model function can be developed specifically for the Great Lakes using long-term data from satellite scatterometers, to derive more accurate wind fields for operational applications as well as scientific studies.

PICHLOVA, R., and Z. Brandl. Predatory impact of Leptodora kindtii on zooplankton community in the Slapy Reservoir. Hydrobiologia 504:177-184 (2003).

The predatory impact of Leptodora kindtii on the zooplankton community of Slapy Reservoir (Czech Republic) was studied using data from regular sampling carried out in 1996-1997. Seasonal changes of abundance and biomass of Leptodora, that directly influence predatory impact, were analyzed and related to both abiotic and biotic parameters. The data suggest that Leptodora can influence the zooplankton community, but only in limited periods during the summer season, with the most pronounced impact in August. Leptodora can apparently accelerate the summer decline of spring cladoceran species, although it does not trigger the shift to summer species.

POTHOVEN, S. A., G. L. FAHNENSTIEL, and H. A. VANDERPLOEG. Spatial distribution, biomass, and population dynamics of Mysis relicta in Lake Michigan. Hydrobiologia 522:291-299 (2004).

The abundance, biomass, and life history traits of Mysis relicta were evaluated in the spring, summer, and autumn of 2000 at 8 nearshore (45 m) and 8 offshore (75-110 m) stations throughout central and southern Lake Michigan. Abundance was also evaluated on a smaller scale during June 2000 at 4 nearshore and 4 offshore stations in southeastern Lake Michigan. For large-scale sampling, the abundance of M. relicta did not differ among locations in the spring. In the summer and autumn the abundance of M. relicta was similar among offshore stations withthe exception of one station each season; for nearshore stations, abundance was generally highest off Pentwater, Michigan. The abundance of mysids was not consistently high for central or southern basin sites, although overall biomass was higher in the southern basin each season. Abundance of Mysis was positively correlated with bottom depth, but not with bottom water temperature, surface water temperature, or mean chlorophyll concentration. Within the smaller region in southeast Lake Michigan, the abundance of M. relicta differed among locations for both nearshore and offshore stations. Brood size and size of reproductive females did not differ among lake widelocations, but the proportion of females with broods and the size distribution of M. relicta did.

RAIKOW, D. F. Food web interactions between larval bluegill (Lepomis macrochirus) and exotic zebra mussels (Dreissena polymorpha). Canadian Journal of Fisheries and Aquatic Sciences 61(3):497-504 (2004).

Food web interactions between native larval bluegill (Lepomis macrochirus), exotic invasive zebra mussels
(Dreissena polymorpha), and zooplankton were examined with a mesocosm experiment. Hatchling larval bluegill collected from nests were reared in the presence of size-structured populations of zebra mussels in 1500-L limnocorrals suspended in an artificial pond for 2 weeks. Chlorophyll a, other limnological variables, and zooplankton abundance and biomass (including copepod nauplii and rotifers) were monitored over time. During their first 2 weeks of life, larval fish reared in the presence of mussels grew 24% more slowly than fish reared alone. Differential growth rates can be explained by competition between mussels and bluegill for food in the form of microzooplankton. Also likely was an indirect competition via starvation of the zooplankton community as zebra mussels consumed phytoplankton. Either direct or indirect trophic competition between zebra mussels and obligate planktivores may result in ecological harm as zebra mussels spread throughout inland lakes of North America.

Rao, Y. R., M. J. McCORMICK, and C. R. Murthy. Circulation during winter and northerly storm events in southern Lake Michigan. Journal of Geophysical Research 109(C1):C01010 (2004).

Moored observations of winds, currents, and temperature made off the southeastern Lake Michigan shore during 1998 to 2000 winter-spring periods are studied to describe the mean winter circulation and episodic circulation during northerly storms in Lake Michigan. Late winter-spring sediment plumes in southeastern Lake Michigan were attributed to these episodic circulation features. The winter-spring currents in southeastern Lake Michigan are quite depth independent, and the mean currents flow predominantly alongshore and toward the north. The observed currents show the signature of a forced two-gyre circulation in the southeastern basin. The interannual variability of mean and fluctuating currents is mainly due to the variability of prevailing wind-forcing. The intermittent episodic circulation influenced by northerly storms causes significant asymmetry to the mean circulation. During northerly storm episodes, the mean current speeds increased significantly, and the currents within 10 km of shore followed the surface wind stress, while farther offshore the circulation was oppositely directed. During these episodes it is also observed that the combination of directly wind-forced currents and northward propagating vorticity wave generates significant offshore transport in this region.

REID, D. F. NOAA National Center for Research on Aquatic Invasive Species. NOAA Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (color brochure) 2 pp. (2003).

Aquatic invasive species (AIS) are a global problem that threaten the economic security of the United States by changing and reducing the beneficial uses that society makes of coastal ecosystems and by adding to the time and cost of conducting commerce and trade related to coastal ecosystems. AIS will frustrate NOAA’s strategic goal of developing ecosystem forecast capabilities and improving ecosystem-based management. In order to maximize the effectiveness and benefits of NOAA’s research investments towards understanding, preventing, responding to, and managing AIS invasions in U.S. coastal ecosystems, the NOAA National Center for Research on Aquatic Invasive Species was established in July 2003. The Center is administratively housed at the Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor, Michigan, and functions in conjunction with the newly created NOAA Invasive Species Program managed at NOAA headquarters in Silver Spring, Maryland.

Rohli, R. V., S. A. Hsu, B. M. LOFGREN and M. R. Binkley. Bowen ratio estimates over Lake Erie. Journal of Great Lakes Research 30(2):241-251 (2004).

Estimates of the ratio of sensible heat flux to latent heat flux (the Bowen ratio) are derived for Lake Erie based on the method introduced by Roll (1965), using hourly automated observations of lake and air temperatures for Buoy 45005 for the period 1992-1997 (May through November). Roll's method computes B as the product of the drag coefficient (which varies by atmospheric stability class) and the ratio of the difference between lake temperature (Tea) and air temperature (Tair), to the sea-air vapor pressure difference. diurnal latter can be estimated empirically as a function of Tsea and dew point temperature (Td). In the diurnal cycle, B usually peaks in the afternoon hours and tends to increase as the warm season proceeds. Specifically, during unstable atmospheric conditions, ? varies from approximately .15 to .30, and during times of high static stability, B tends to have near-zero to slightly negative values. Results allow for an improved understanding of turbulent energy fluxes from a large water body, which may affect other processes, such as ice cover, evaporation rates, and contaminant advection.

Roy, D., G. D. Haffner, and S. B. BRANDT. Estimating fish production potentials using a temporally explicit model. Ecological Modeling 173:241-257 (2004).

A temporally explicit model is developed to predict the growth rate potential of fish in response to temporal fluctuations in both prey availability and temperature structure of the water column at both long (seasonal) and short (daily) time scales. The model was tested in a 20m water column in Lake Ontario using chinook salmon (Oncorhynchus tshawytcsha) and alewife (Alosa pseudoharengus) as predator and prey species, respectively. Prey availability was assessed using acoustic techniques, while temperature was measured with a temperature–depth profiler. Chinook growth rate potential was significantly greater during June than during other sampled months. The latter months supported little to no chinook growth potential as a result of low overlap in conditions supporting growth. On a diel scale, chinook growth rate potential was typically greater during crepuscular and night periods than during the day. Results reveal that both short and long term variability of prey density and thermal structure impose stringent limits to fish growth potential and production, and that fish grow well only over finite periods. The temporally explicit model provides quantitative predictions of fish production potential as influenced by temporal changes in habitat quality and/or climatic conditions. In light of recent modifications to both local and regional climate conditions, and the localised nature of fish harvesting practices, this model can assist in setting realistic production estimates and future potential harvesting quotas.

SANO, L. L., M. A. Mapili, A. Krueger, E. Garcia, D. C. GOSSIAUX, K. Phillips, and P. F. LANDRUM. Comparative efficacy of potential chemical disinfectants for treating unballasted vessels. Journal of Great Lakes Research 30(1):201-216 (2004).

The release of ballast water from transoceanic vessels is a major vector for the introduction of nonindigenous species into the Laurentian Great Lakes. This study assessed the effectiveness of treating unballasted transoceanic vessels using three different biocides: glutaraldehyde plus a surfactant adjuvant (Disinfekt 1000®), sodium hypochiorite (NaOCl), and SeaKleenTM (menadione and menadione metabisulfIte 2:8). Efficacy against several classes of aquatic organisms was evaluated using 24 h acutetoxicity experiments and 11 day ballast tank simulation experiments. The results indicate substantial, compound-specific variations in organism sensitivity. For water-only exposures, NaOCZ and SeaKleenTM were most effective: NaOC1 had the lowest LC90 (90% lethal concentration value) for the oligochaete Lumbriculus variegatus (1.0 mg L-1), while SeaKleenTM had the lowest LC90 for the amphipod Hyalella azteca (2.5 mg L-1). Sediments profoundly affected efficacy, particularly for NaOC1: At a 1:4 sediment-water ratio, the estimated LC90 for L. variegatus was > 2,000 mg L-1. Sediment quality also impacted efficacy: Sediments with higher organic carbon content typically required greater biocide concentrations to achieve comparable toxicity. Efficacy was further evaluated with 11 day bioassays using sedimentsfrom unballasted vessels. Results indicated that NaOCl and Disinfekt 1000® were more effective than predicted based on small scale sediment-water exposures. Overall, the data suggest that although NaOC1 may be effective under water-only conditions, the higher concentrations required in the presence of sediments may cause corrosion problems for ballast tanks. Because of this, less reactive, non-oxidizing biocides such as SeaKleenTM and Disinfekt 1000® may be better candidates for treating sedimented tanks.

SANO, L. L., R. A. Moll, A. M. KRUEGER, and P. F. LANDRUM. Assessing the potential efficacy of Glutaraldehyde for biocide treatment of un-ballasted transoceanic vessels. Journal of Great Lakes Research 29(4):545-557 (2003).

Treating the ballast water of oceanic vessels with a biocide is one potential management strategy to reduce the number of nonindigenous species released into the Laurentian Great Lakes from NOBOB (no ballast on board) vessels. To evaluate biocide effectiveness, glutaraldehyde, a five-carbon dialdehyde widely used for its antimicrobial properties, was investigated. Biocide effectiveness was assessed for various organisms using 24 h acute toxicity bioassays in water-only and water-sediment environments. Acute studies indicate a 24 h LC90 value of 100 mg glutaraldehyde L-1 or less for most of the freshwater organisms tested. The main exception was the freshwater amphipod, Hyalella azteca, which was much more resistant to glutaraldehyde (24 h LC90 = 550 mg glutaraldehyde 1r1; 95% CI: 476-681). Biocide efficacy was also evaluated in water-sediment exposures. The presence of a test sediment (3% organic carbon) greatly increased lethal concentration estimates for the oligochaete Lumbriculus variegatus, but not for H. azteca. The 24 h LC90 for L. variegatus varied depending on the water-sediment ratio, and ranged from 61 mg glutaraldehyde L-1 (95% CI 52-78) for an 8:1 water-sediment ratio to 356 mg glutaraldehyde L-1 (95% CI 322-423) for a 2:1 water-sediment ratio. This indicates that the amount of sediments present in NOBOB vessels may have a significant impact on biocide efficacy. Experiments using material from actual NOBOB vessels generally corroborated data from the water-sediment experiments and suggest a potential treatment concentration of approximately 500 mg glutaraldehyde L-1for short exposure periods (e.g., 24 h).

SCHWAB, D. J., and D. BELETSKY. Relative effects of wind stress curl, topograph, and stratification on large scale circulation in Lake Michigan. Journal of Geophysical Research 108(C2):26-1 to 26-6 (2003).

This paper uses the results from two multiseason numerical model simulations of Lake Michigan hydrodynamics to examine the relative effects of wind stress curl, topography, and stratification on large-scale circulation. The multiseason simulations provide a period long enough to encompass the full range of atmospheric and thermal conditions that can occur in the lake. The purpose of this paper is to diagnose the relative importance of various mechanisms responsible for the large-scale circulation patterns by analyzing the vorticity balance in the lake on a monthly timescale. Five different model scenarios are used to isolate the predominant mechanisms: (1) baroclinic lake, spatially varible wind stress; (2) barotropic lake, spatially variable wind stress; (3) baroclinic lake, spatially uniform wind stress; (4) baritropic lake, spatially uniform wind stress; and (5) barotropic lake, linearized equations, spatially uniform wind stress. By comparing the results of these five model scenarios it is shown that the cyclonic wind stress curl in the winter and the effect of baroclinicity in the summer are primarily respnsible for the predominantly cyclonic flow in the lake. Topographic effects are as important but are not as significant as wind stress curl and baroclinic effects. Nonlinear effects are much smaller.

Thayer, G. W., T. A. McTigue, R. J. Bellmer, F. M. Burrows, D. H. MERKEY, A. D. Nickens, S. J. LOZANO, P. F. Gayaldo, P. J. Polmateer, and P. T. Pinit. Science-based restoration monitoring of coastal habitats. Volume One: A framework for monitoring plans under the Estuaries and Clean Waters Act of 2000 (Public Law 160-457). NOAA Coastal Ocean Program, Decision Analysis Series No. 23, Volume 1. NOAA, Coastal Ocean Program, Silver Spring, MD, 116 pp. (2003). or

Science-Based Restoration Monitoring of Coastal Habitats, Volume One: A Framework for Monitoring Plans Under the Estuaries and Clean Waters Act of 2000 (Public Law 160-457), is a guidance manual that provides technical assistance, outlines necessary steps, and provides useful tools for the development and implementation of sound scientific monitoring of coastal restoration efforts. This document is a result of the Estuary Restoration Act (ERA), Title I of the Estuaries and Clean Waters Act of 2000. The National Oceanic and Atmospheric Administration (NOAA) was tasked with providing guidance for the development and implementation of restoration monitoring for projects funded under the Act. In addition to it’s usefulness to restoration practitioners undertaking ERA projects, this document has broad application and will assist in the monitoring of coastal restoration projects regardless of their funding source.The manual represents the first of a two volume series. This first volume contains a background on restoration and monitoring, stages of a restoration and monitoring plans, how to create a monitoring plan, and important information that should be considered when monitoring specific habitats. The second volume, to be published in 2004, provides detailed information on the habitats, an inventory of coastal restoration monitoring programs, a review of monitoring techniques manuals and quality control/quality assurance documents, an overview of governmental acts affiliated with monitoring, a cost analysis of monitoring expenses, a glossary of terms, and a discussion of socioeconomic issues affiliated with coastal habitat restoration.

VANDERPLOEG, H. A. Ecological forecasting of impacts of ponto-caspian species in the Great Lakes: Describing, understanding, and predicting a system in transition. In Ecological Forecasting: New Tools for Coastal and Marine Ecosystem Management. N. Valette-Silver and D. Scavia (Eds.). NOAA Technical Memorandum NOS NCCOS 1, Silver Spring, MD, 81-84 (2003).

This paper summarizes results relevant to ecological forecasting from a study that described, explained, and predicted Great Lakes ecosystem impacts of six Ponto-Caspian (the region including the Caspian, Black, and Azov Seas) endemic species of mussels, crustaceans, and fishes that recently invaded the Great Lakes via ballast water (Vanderploeg et al. 2002). These are the zebra mussel (Dreissena polymorpha), the quagga mussel (D. bugensis), the predatory cladoceran (Cercopagis pengoi), the benthic amphipod (Echinogammarus ischnus), the round goby (Neogobius melanostomus), and the tubenose goby (Proterorhinus marmoratus). The ecology, and possible mechanisms of ecosystem impact were reviewed for each species using information from a variety of studies and sites, including the Great Lakes. This information was combined with experiments and monitoring on the Great Lakes to describe ecosystem change, the underlying invader species mechanisms of impact, and predict future changes.

Zhulidov, A. V., D. F. Pavlov, T. F. NALEPA, G. H. Scherbina, D. A. Zhulidov, and T. U. Gurtovaya. Relative distributions of Dreissena bugensis and Dreissena polymorpha in the lower Dan River, Russia. International Review of Hydrobiology 89(3):326-333 (2004).

A survey was conducted in the lower Don River system in Russia to confirm the presence of Dreissena bugensis, and to compare its distribution relative to that of Dreissena polymorpha. In 1999 and 2001–2002, dreissenid mussels were collected at 15 sites in the main river, in connecting reservoirs, and in a major tributary, the Manych River. Collections were made near stations where long-term monitoring data on total mineral (sum of principal ions) and calcium content were available. Both dreissenid species were found at all sites, with D. bugensis comprising 4–75% of all dreissenids at individual sites. D. bugensis was relatively more abundant than D. polymorpha in the Manych River where total mineral and calcium content was significantly higher than in the Don River, suggesting the two species may have different calcium requirements. Examination of archived samples indicated that D. bugensis was present in the Don River system as early as the 1980s, presenting the unresolved enigma of why D. bugensis has not displaced D. polymorpha as the dominant species as typically found over shorter time periods in other water bodies.

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