GLERL Publication Abstracts: FY 2000

ASSEL, R. A., J. E. Janowiak, D. Boyce, C. O'Connors, F. H. QUINN, and D. C. NORTON. Laurentian Great Lakes ice and weather conditions for the 1998 El Nino winter. Bulletin of the American Meteorological Society 81(4):703-717 (2000). http://www.glerl.noaa.gov/pubs/fulltext/2000/2000001.pdf

Winter 1997/98 occurred during one of the strongest warm El Nino events, and the Great Lakes experienced one of the least extensive ice covers of this century. Seasonal maximum ice cover for the combined area of the Great Lakes was the lowest on record (15%) relative to winters since 1963, a distinction formerly held by winter 1982/83 (25%), which was also an exceptionally strong E1 Nino winter. Maximum ice covers set new lows in winter 1997/98 for Lakes Erie (5%), Ontario (6%), and Superior (11%), tied the all-time low for Lake Huron (29%), and came close to tying the all-time low on Lake Michigan (15%; all-time low is 13%). Here the authors compare seasonal progression of lake-averaged ice cover for winter 1982/83, winter 1997/98, and a 20-winter normal (1960-79) derived from the NOAA Great Lakes Ice Atlas and discuss the 1997/98 ice cover in detail. Winter air temperatures in the Great Lakes were at or near record high levels, storms were displaced farther to the south over eastern North America, and precipitation was below average in the northern portion of the Great Lakes region. The Northern Hemispheric synoptic flow patterns responsible for this winter weather, the Great Lakes winter severity over the past two centuries, and impacts of this mild winter are briefly discussed.

BEETON, A. M., C. E. SELLINGER, and D. F. REID. An introduction to the Laurentian Great Lakes ecosystem. In Great Lakes Fisheries Policy and Management: A Binational Perspective, W.W. Taylor and C.P. Ferreri (Eds.), Michigan State University, East Lansing, MI, pp. 3-54 (1999).

Physical processes that occur in the Great Lakes influence the distribution of nutrients, geographic location, and relative abundance of the biological communities. Processes such as water movement, which are important to the distribution of benthos and plankton, are ultimately responsible for the location of Great Lakes fish, which feed heavily on these biota. Additional physical processes, such as light penetration and water temperature are also responsible for the locadon and abundance of Great Lakes biota. Since light is the important factor in photosynthesis, the quantity and quality of light penetrating the water column controls the nourishment and growth of phytoplankton. Light is also important for distribution of zooplankton (e.g., vertical migrations). Temperature, which varies due to latitude and depth of a particular lake, influences the distribution and abundance of Great Lakes invertebrate fauna. Simply put, the upper deep Great Lakes have different zooplanktonic and zoobenthic fauna than the shallow waters of Green Bay, Saginaw Bay, and Lake Erie due partially to cooler temperatures. Water level changes, although not as dynamic as water movement, indirectly affect the biota's habitats. Variations in water levels on a seasonal, long period. or geologic-time-scale basis affect coastal wetlands, shore erosion, resuspension of sediments, and the depth in the water column. Underlying these physical processes is the basin morphology. Not only do latitude and depth determine water temperature, but climatic patterns and water abundance are geographically specific. Therefore, this section will briefly describe basin morphology, or watershed dimensions; provide an explanation of how water is maintained in the Great Lakes; ti.e., the water budget) describe the optical properties of the water column; and conclude with examples of processes that are responsible for water movement.

BELETSKY, D., D. J. SCHWAB, M. J. McCORMICK, G. S. MILLER, J. H. SAYLOR, and P. J. Roebber. Hydrodynamic modeling for the 1998 Lake Michigan coastal turbidity plume event. Proceedings of the Conference on Estuarine and Coastal Modeling, New Orleans, LA, November 3-5, 1999. American Society of Civil Engineers, Reston, VA, pp. 597-613 (2000).

A three-dimensional primitive equation numerical ocean model, the Princeton model of Blumberg and Mellor (1987), was applied to Lake Michigan to simulate hydrodynamic conditions during the 1998 coastal turbidity plume event. A massive turbidity plume in southern Lake Michigan was caused by a strong storm with northerly winds up to 17 m/s during this period. The hydrodynamic model of Lake Michigan has 20 vertical level Is, and a uniform horizontal grid size of 2 km. The model is driven with surface momentum flux derived from observed meteorological conditions at 12 land stations in March 1998 and also with surface winds calculated using the mesoscale meteorological model MMS (Dudhia, 1993)on a 6 km grid. Current observations from 11 subsurface moorings showed that while the model was able to qualitatively simulate wind-driven currents, it underestimated current speeds during strong wind events and in particular an onshore-offshore component of the flow in the area of observations. This may be due at least in part to the significant decrease of modeled current speeds with depth during strong wind events while observed currents showed almost no vertical shear. Hydrodynamic model results using MMS winds as the forcing function were slightly better than results which were based on objectively analyzed winds.

BRIDGEMAN, T. B., G. Messick, and H. A. VANDERPLOEG. Sudden appearance of cysts and ellobiopsid parasites on zooplankton in a Michigan lake: a potential explanation of tumor-like anomalies. Canadian Journal of Fisheries and Aquatic Science 57(8):1539-1544 (2000). http://www.glerl.noaa.gov/pubs/fulltext/2000/20000002.pdf

Cysts on calanoid and cyclopoid copepods, previously reported as tumor-like anomalies (TLAs) in Lake Michigan and Europe, appeared briefly in Patterson Lake, a small Michigan inland lake. Cysts were rare (4% maximum) in samples collected on September 11, 1999, but appeared with high frequency on calanoid adults (49%) and cyc1opoid nauplii (73%) in samples collected on October 16. By October 30, cysts were again rare(0.4% maximum). Cysts most commonly appeared on the lateral surface of the animal at the articulation of the 1st and 2nd prosomal segments and often consisted of herniated copepod tissues. Transparent, pyriform cysts co-occurred in low frequency with other types of cysts and are believed to be the trophomeres and gonomeres of ellobiopsid parasites. Histologic manifestations of cysts were diverse; herniations consisted of acellular yolk-like material and apparent host tissue, while cysts thought to be Ellobiopsis contained cells with different degrees of nuclear staining and unusual spherical bodies. Hernias were experimentally induced on live calanoid copepods by piercing the carapace with a fine needle, suggesting that ellobiopsid parasites may cause the hernias by puncturing the carapace of their hosts. Ellobiopsid parasites are common on marine crustacean zooplankton but have been recorded only once before in freshwater.

CROLEY, T. E. II. Adjusting storm frequencies for climate forecasts. Proceedings, American Water Resources Annual Spring Specialty Conference, Anchorage, Alaska, May 3, 2000. pp. 269-274 (2000).

Storm frequency estimates (e.g., maximum precipitation or flow probabilities) allow engineers and hydrologists to assess risks associated with their decisions during the design, construction, and operation of water resource projects. Storm frequencies for the future are often estimated directly from past historical records of sufficient length. The estimation requires no detailed knowledge of the area's meteorology, but presumes it remains unchanged in the future. However, the climate seldom remains static. Numerous climate forecasts of meteorology probabilities over extended periods are now available to the water resource engineer and hydrologist. It is possible to use these meteorology forecasts directly in the estimation of storm frequencies from the historical record. It is more desirable to do so now than at any time past, since meteorology forecasts have been improving and are now better than their predecessors. A heuristic approach is defined here to estimate storm frequencies that recognize forecasts of extended weather probabilities. Basically, those groups of historical meteorology record segments matching forecast meteorology probabilities are weighted more than others, during the estimation of storm frequencies. (Affiliated groups of hydrology record segments may be similarly weighted for hydrological estimation; e.g., flood frequency estimation.) An example frequency estimation of maximum flow is made using currently available agency meteorology forecasts in the US and Canada.

CROLEY, T. E. I. Climate-corrected storm-frequency examples. NOAA Technical Memorandum GLERL-118, NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (NTIS# not yet available) 27 pp. (2000). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-118/tm-118.pdf

Storm frequency estimates (e.g., maximum precipitation or flow probabilities) allow engineers and hydrologists to assess risks associated with their decisions during the design, construction, and operation of water resource projects. Storm frequencies for the future are often estimated directly from past historical records of sufficient length. The estimation requires no detailed knowledge of the area's meteorology, but presumes it remains unchanged in the future. However, the climate seldom remains static. Numerous climate forecasts of meteorology probabilities over extended periods are now available to the water resource engineer and hydrologist. It is possible to use these meteorology forecasts directly in the estimation of storm frequencies from the historical record. It is more desirable to do so now than at any time past, since meteorology forecasts have been improving and are now better than their predecessors. A heuristic approach is defined here to estimate storm frequencies that recognize forecasts of extended weather probabilities. Basically, those groups of historical meteorology record segments matching forecast meteorology probabilities are weighted more than others, during the estimation of storm frequencies. (Affiliated groups of hydrology record segments may be similarly weighted for hydrological estimation; e.g., flood frequency estimation.) Examples include frequency estimation of maximum daily precipitation and maximum flow, using currently available agency meteorological forecasts in the US and Canada as well as El Niño and La Niña conditional probabilities.

CROLEY, T. E. II. Using Meteorology Probability Forecasts in Operational Hydrology. American Society of Civil Engineers, Reston, VA, 206 pp. (2000).

The first of its kind, this book simplifies atmospheric predications enabling laypersons to make their own derivative forecasts immediately. Scientists and engineers can learn to predict weather-dependent phenomena to assess the risks associated witah decisions in the construction and operation phases of water resource planning. This self-educating method simultaneously uses probabilistic meteorology forecasts over different time scales, time periods, spatial domains, probability statements, and meteorology variables. Using Meteorology Probability Forecasts in Operational Hydrology is a practical hands-on guide filled with comprehensive and straighforward theory, procedures, and examples for using short-term, seasonal, and interannual forecasts of meteorology probabilities, available from the National Oceanic and Atmospheric Administration, Environment Canada, and other agencies. The examples use different hydrology models; employ both user-defined and agency produced meteorology probability forecasts in the United States and Canada; illustrate El Nino and La Nina conditional probabilities and examples of their derivation; and provide sufficient information for the reader's own applications. An extensive appendix describes the acquisition, installation, and use of freely available software to prepare historical files for individualized applications, to input forecast meteorology probabilities of a specific site, to extract reference quantile estimates, to prioritize forecasts, and to solve the resulting set of equations for derivative forecasts.

DEMERS, E., S. B. BRANDT, K. L. BARRY, and J. M. JECH. Spatially-explicit models of growth rate potential: linking estuarine fish production to the biological and physical environment. In Estuarine Synthesis: A Synthetic Approach to Research and Practice, J.E. Hobbie (Ed.), Island Press, Washington, DC, pp. 405-425 (2000).

Estuaries are high-yield fishing areas that are characterized by spatial heterogeneiq in physical and biological conditions. Models of fish production have traditionally been based on systemwide averages of environmental conditions, but habitat heterogeneity can substantially infiuence fish growth. Growth rate potential (GRP) provides a spatially explicit approach that integrates the heterogeneous nature of estuaries into a simple modeling framework. In this chapter, we describe and illustrate the application of GRP to compare potential growth of two piscivQres and to determine the potential growth of a non-native species introduced into an estuary. Acoustically derived prey distributions and temperature profiles were merged in a spatially explicit analysis to estimate and compare GRP of striped bass and bluefish in Chesapeake and Delaware Bays. In this analysis, bluefish grew better in the thermal regimes and prey biomass available during midsummer while striped bass had higher potential growth during fall. This suggests that, although striped bass and bluefish use similar prey resources, they may be thermally and temporally segregated, thereby reducing competitive overlap. In our second example, GRP results indicate that the suitability of Chesapeake Bay for the growth of chinook salmon (a non-native, hypothetical invader) was very low during summer, whereas in October, water temperature and prey availability could possibly support chinook salmon growth. This spatially explicit approach proved to be a valuable tool to study fish production in estuarine systems where heterogeneous conditions can affect populations at systems levels.

EADIE, B. J., G. S. MILLER, M. B. LANSING, and A. G. WINKELMAN. Settling particle fluxes and current and temperature profiles in Grand Traverse Bay, Lake Michigan. NOAA Technical Memorandum GLERL-116, NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (NTIS# PB2000-103355/XAB) 25 pp. (2000). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-116

Settling particle fluxes and mass flux profiles are reported for trap samples collected at five stations in Grand Traverse Bay, Lake Michigan during 1997-1999. Trap collection precision is estimated, and 10 cm and 20 cm diameter sequencing traps are inter-calibrated using data from traps deployed in replicate on specially constructed brackets. Temperature data is reported for two stations (during June-September 1997). Acoustic Doppler Current Profilers (ADCP) current meter data and contours of backscatter strength, U and V current components, and water temperature are included for the 95 m station. All data is available online in ASCII and MS Excel formats at ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-116.

Gardner, W. S., P. J. Lavrentyev, H. A. Bootsma, J. F. CAVALETTO, F. Troncone, and J. B. Cotner. Effects of natural light on nitrogen dynamics in diverse aquatic environments. Verh. International Verein. Limnology 27:64-73 (2000).

Solar radiation is a major force affecting the ecosystem dynamics of aquatic and terrestrial ecosystems. As the source of energy for photosynthesis, it allows plants to assimilate nutrients into energy-rich organic material at the base of food webs and provides energy for biogeochemical processes. The importance of the quality and quantity of light has been studied extensively in terms of its relationship to photosynthetic processes (e.g. KIRK 1994). The effect of light on nitrogen cycling in aquatic ecosystems has been less studied and has not been defined clearly, except for several studies of nutrient uptake as related to primary production processes (e.g. COCHLAN et al. 1991 and references cited therein) . Light provides energy for photosynthesis and increases inorganic nutrient uptake, but excess light can also inhibit phytoplankton growth and nutrient uptake. These effects depend not only on the intensity of the light but also on its spectral characteristics and the physiology of component organisms. The effects of light on heterotrophic nutrient regeneration processes are less apparent than are those for phytoplankton uptake processes because heterotrophic organisms do not usually depend on light for energy. For this reason, metabolic studies of heterotrophic aquatic organisms are usually conducted under dark conditions. However, light could affect biological nutrient regeneration mechanisms and rates in a variety of indirect ways. To develop an understanding of these effects, we must define the mechanisms of food web interactions and photochemical stimuli that may affect them. Additionally, ultraviolet light may affect nitrogen regeneration by photochemically converting dissolved organic nitrogen (or complexed inorganic forms) to ammonium or nitrate in surface waters (Bushaw et al.1996).

Great Lakes Environmental Research Laboratory. Great Lakes Water Levels. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2000). http://www.glerl.noaa.gov/pubs/brochures/broch.html

If you wander down the shores of Lake Michigan nowadays, it's difficult not to notice that beaches seem curiously wide: rocks that were once arely visible now jut from the waves. Marina docks seem built too high for the boats that pull up to them. A glance at the pilings tells why: the dark line marking the lake levels of previous years is three feet about the water. Since 1998, the level of Lakes Michigan and Huron has dropped at the fatest pace ever recorded. Long-time residents have been reminded of the droughts of the 1930s and 1960s, when water levels also fell dramaticaly. Many more have grown concerned about the impact upon both the shipping industry and the environment.

HAWLEY, N., and C.-H. Lee. Sediment resuspension and transport in Lake Michigan during the unstratified period. Sedimentology 46:791-805 (1999).

Instrumented moorings were deployed during the winter of 1994-95 at three depths (28, 58 and 101 m) in southern Lake Michigan. Storms during the observation period were not unusually severe, so the processes observed are typical of those that occur during an average winter. Time series observations of water temperature, beam attenuation coefficient (a measure of water transparency) and current velocity show that local resuspension of bottom sediment occurred frequently after the breakdown of the thermocline. Resuspension was most frequent close to the shore but was also observed at the 58 m station. Local resuspension did not occur at the 101 m station, but advection to the site of material resuspended at shallower sites was observed. These observations do not support the hypothesis proposed by previous investigators that local resuspension at depths of 100 m or greater occurs during the unstratified period. It is more likely that fine-grained material resuspended by storm action in intermediate water depths (= 30-60 m) is transported into the deeper parts of the lake by the general lake circulation.

HORNE, J. K., P. E. Smith, and D. C. Schneider. Comparative examination of scale-explicit biological and physical processes: recruitment of Pacific hake (Merluccius productus). Canadian Journal of Fisheries and Aquatic Sciences 56(1):170-179 (1999). http://www.glerl.noaa.gov/pubs/fulltext/1999/19990010.pdf

The creation, maintenance, and destruction of aquatic organism distributions result from biological and physical processes that operate at different spatial and temporal scales. Rate diagrams plot and contour ratios of process rates as a function of spatial and temporal scale to summarize the relative importance of demographics, growth, and kinematics. We demonstrate the utility of this approach by examining physical and biological processes that influence the distribution and survival of larval and juvenile Pacific hake (Merluccius productus) in the California Current region. Processes that influence changes in hake biomass switch from mortality and drift among larvae to somatic growth and active locomotion among juveniles: Comparison of hake rate diagrams with those of capelin (Mallotus villosus) and Atlantic cod (Gadus morhua) show that dominant processes differ across scales, across life history stages, and across species.

Houde, E. D., S. Jukic-Peladic, and S. B. BRANDT. Fisheries: Trends in Catches, Abundance and Management. In Ecosystems at the Land-Sea Margin, T. Malone et al. (Eds.), 341-366 (1999).

Fisheries of the Chesapeake Bay (CB) and Northern Adnatic Sea (NA) are reviewed and compared with respect to constituents ofthe catch, trends, and management issues. Recent nnnual landings have been approximately 100,000 and 275,000 tons in the NA and CB, respectively. Clupeoid fishes (anchovies, sardines or menhaden) dominate the fish biomasses and catches in both ecosystems. Fishenes on anadromous and estuarine dependent species are more important in CB, and diverse, demersal fisheries are relatively more important in NA. Although total catches have remained high, anchovy stocks in the NA collapsed in the 1980s, and oysters and shad/ever herring stocks in CB declined to collapses duriug the past three decades. Eutrophication, overfishing, and problems of interjurisdictional management are common to the two ecosystems. The co-management of commercial and recreational fisheries is an issue in CB. Fish productivity and catches are higher in CB than in the NA on a per unit volume, area, and nutrient input basis. Yield per unit of prunary production is slightly higher in the NA. A part of the difference between the two systems is accounted for by the dominance of landings and production of menhaden, a phytoplanktivore, from Chesapeake Bay. Recent progress in development of national and international management accords (Slovenia, Croatia, Italy) is evident in the NA, and interstate plans are now required in the CB. In both systems, prospects for continued high fisheries productivity depend upon effective ecosystem and fisheries management.

JECH, J. M., and J. Luo. Digital Echo Visualization and Information System (DEVIS) for processing spatially-explicit fisheries acoustic data. Journal of Fisheries Research 27:115-124 (2000).

Spatially explicit analysis of fisheries acoustic data preserves heterogeneity observed in spatial distributions of fish. A software system–Digital Echo Visualization and Information System (DEVIS)–has been developed to process digital underwater acoustic data for spatially-explicit fisheries acoustic research. This system can be used to obtain spatial and temporal distributions of fish density, fish abundance, and fish lengths for management applications and for ecological modeling. DEVIS first reads digital data, corrects the data according to the sonar equation, discriminates individual targets, and vertically and horizontally integrates the data into a two-dimensional array of mean volume backscattering strength. Individual target information (TS, spatial location) is meshed with the volume backscattering array, and representative acoustic sizes are estimated in array cells with missing target information. Estimation methods for acoustic sizes and potential biases in abundance estimates are introduced and discussed. The final output is the spatial distribution of numeric density and fish length by length classes and for all fish. Data obtained on Lake Erie in September 1994 and on Chesapeake Bay in July 1995 were processed using DEVIS and are shown graphically. Steps required to process digital data are described and how these data can be applied to fish ecology is shown.

JOHENGEN, T. H., T. F. NALEPA, G. A. LANG, D. L. FANSLOW, H. A. VANDERPLOEG, and M. A. AGY. Physical and chemical variables of Saginaw Bay, Lake Huron in 1994-1996. NOAA Technical Memorandum GLERL-115, NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (NTIS# PB2000-102421/XAB) 39 pp. (2000). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-115

Physical and chemical data were collected in Saginaw Bay, Lake Huron over the period 1991—1996 as part of a monitoring program to assess the ecological impact of the zebra mussel, Dreissena polymorpha. This report presents monitoring results for the years 1994—1996 and builds upon the previous technical memorandum GLERL-91 (ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-091/) that described results for the years 1991—1993. Detailed accounts of sampling times, locations, and methods, and analytical procedures are included in each of the reports.

LANDRUM, P. F., S. W. Fisher, H. Hwang, and J. Hickey. Hazard evaluation of ten organophosporous insecticides against the Midge, Chironomus riparius via QSAR. SAR and QSAR in Environmental Research 10:423-450 (1999).

Toxicities of ten organophosphorus (OP) insecticides were measured against midge larvae (Chironomus riparius) under varying temperature (11,18, and 25°C) and pH (6,7, and 8) conditions and with and without sediment. Toxicity usually increased with increasing temperature and was greater in the absence of sediment. No trend was found with varying pH. A series of unidimensional parameters and multidimensional models were used to describe the changes in toxicity. Log Kow was able to explain about 40-60% of the variability in response data for aqueous exposures while molecular volume and aqueous solubility were less predictive. Likewise, the linear solvation energy relationship (LSER) model only explained 40-70% of the response variability, suggesting that factors other than solubility were most important for producing the observed response. Molecular connectivity was the most useful for describing the variability in the response. In the absence of sediment, 1x^v and ³K were best able to describe the variation in response among all compounds at each pH (70-90%). In the presence of sediment, even molecular connectivity could not describe the variability until the partitioning potential to sediment was accounted for by assuming equilibrium partitioning. After correcting for partitioning, the same molecular connectivity terms as in the aqueous exposures described most of the variability, 61-87%, except for the 11°C data where correlations were not significant. Molecular connectivity was a better tool than LSER or the unidimensional variables to explain the steric fitness of OP insecticides which was crucial to the toxicity.

LANDRUM, P. F., J. Kukkonen, M. J. Lydy, and H. Lee II. Measuring absorption efficiencies: Some additional considerations. Environmental Toxicology and Chemistry 18(11):2403-2405 (1999).

No abstract.

LAVRENTYEV, P. J., W. S. GARDNER, and L. Yang. Effects of the zebra mussel on nitrogen dynamics and the microbial community at the sediment-water interface. Aquatic Microbial Ecology 21:187-194 (2000).

A flow-through experiment was conducted on intact cores of sediments from Saginaw Bay, Lake Huron, to examine how trophic interactions between filter-feeding bivalve mussels and microbial populations could affect nitrogen dynamics at the sediment-water interface. The zebra mussels used in this experiment removed a large proportion of protozoa and phytoplankton from the overlying water, particularly heterotrophic nanoplankton (up to 82%), while bacterial populations showed less change. A 3-fold decrease in the protozoan to bacterial carbon ratio corresponded to a 2.5-fold increase in relative ammonium removal rates as estimated from the dark loss of i5N-ammonium. Excretion by the bivalves also increased net ammonium flux to the water, thus elevating the total calculated areal ammonium removal rates to about 6-fold over rates observed in the control treatment. These data suggest that filter-feeding bivalves may significantly affect nitrogen transformation rates near the sediment-water interface by excreting ammonium and altering the microbial food web structure at the sediment-water interface.

LEE, D. H., and L. M. Abriola. Use of the Richards equation in land surface parameterizations. Journal of Geophysical Research 104(D22):27,519-27,526 (1999).

Accurately modeling infiltration and soil moisture within land surface parameterization schemes (LSPs) of coupled land surface-atmosphere models is essential for producing realistic simulations of energy and moisture fluxes and for partitioning precipitation into infiltration, surface runoff, and drainage to groundwater. This report compares simulations of soil moisture, runoff, infiltration, and drainage to groundwater for a bare clay loam using three approaches: a finite difference solution of the vertically integrated Richards equation (an approach commonly used in LSPs), a highly resolved (spatially and temporally) finite element solution of Richards equation, and an analytical kinematic wave solution of Richards equation. Comparisons show that depth-averaged soil moisture simulated using the vertically integrated Richards equation is only similar to those of the finite element solution for vertical spatial discretizations finer than those employed by most state-of-the-art land surface-atmosphere transfer schemes. The vertically integrated Richards equation overpredicts soil moisture in the near-surface soil column and underpredicts drainage to groundwater. The infiltration formulation is found to be critical in partitioning precipitation into runoff, soil moisture, and drainage. Different infiltration formulations and vertical spatial discretizations may partly explain the very different land surface moisture and energy fluxes reported by the LSPs evaluated as part of the Project for Intercomparison of Land Surface Parameterization Schemes (PILPS) Phase 2(b) experiment.

LESHKEVICH, G. A., and S. Liu. Internet access to Great Lakes CoastWatch remote sensing information. Proceedings, IEEE 2000 International Geoscience and Remote Sensing Symposium, Honolulu, HI, July 24-28, 2000. IEEE (2000).

CoastWatch is a nationwide National Oceanic and Atmospheric Administration (NOAA) program started as the result of an occurrence of Red Tide off the North Carolina coast in 1987. Within this program, the Great Lakes Environmental Reseach Laboratory (GLERL) functions as the Great Lakes CoastWatch regional node. In this capacity, GLERL obtains, produces, and delivers environmental data and products for near real-time monitoring of the Great Lakes to support environmental science, decision making, and supporting research. This is achieved by providing Internet observations, in-situ Great Lakes data, and derived products to Federa, state, and local agencies, academic institutions, and the public via the Great Lakes CoastWatch web siste (http:coastwatach.glerl.noaa.gov). To make Great Lakes CoastWatch imagery and in situ data more useful, a new tool utilizing a JAVA applet is implemented on the web site. The JAVA applet (JAVA GIS) allows the interactive viewing and analysis of satellite surface temperature and visible imagery with data overlays such as bathymetry, gridded wind fields, and marine observation (buoy, CMAN, CoastGuard) data.

LESHKEVICH, G. A., S. V. Nghiem, and R. Kwok. Monitoring Great Lakes ice cover with satellite synthetic aperture radar (SAR). Proceedings, IEEE 2000 International Geoscience and Remote Sensing Symposium, Honolulu, HI, July 24-28, 2000. IEEE (2000).

During the 1997 winter season, shipborne polarimetric backscatter measurement of Great Lakes ice types using the Jet Propulsion Laboratory (JPL) C-band scatterometer, together with surface-based ice physical characterization measurements and environmental parameters were acquired concurrently with RADARSAT and ERS-2 SAR data. Using a supervised classification algorithm, measured backscatter values (converted to dB) for three ice types and calm water were applied to an 8 x 8 pixel averaged ERS-2 calibrated SAR image. Certain assumptions were made on the local incidence angle across a distributed target was neglected, i.e. a distributed target corresponds to one average value of the incidence angle (23^o was used). Although the calculated overall uncertainty was about +/- 1 dB as a result of the averaging and indicence angle effect, an algorithm to correct for power loss and local incidence angle effect is applied in this study to the ERS-2 image, resulting in a more accurate classification.

LESHKEVICH, G. A., D. J. SCHWAB, G. C. MUHR, and S. LIU. World Wide Web access to Great Lakes CoastWatch environmental data. Proceedings, AWRA Symposium on Water Resources and the World Wide Web, Seattle, WA, December 5-9, 1999. American Water Resources Association, 10 pp. (2000).

CoastWatch is a nationwide National Oceanic and Atmospheric Administration (NOAA) program within which the Great Lakes Environmental Research Laboartory (GLERL) funcations as the Great Lakes regional node. In this capacity, GLERL obtains, produces, and delivers environmental data and products for near real-time monitoring of the Great Lakes to support environmental science, decision making, and supporting research. This is achieved by providing Internet access to near real-time and retrospective satellite observations, in-situ Great Lakes data, and derived products to Federal, state, and local agencies, acedemic institutions, and the public via the Great lakes CoastWatch web site (http:/coastwatch.glerl.noaa.gov). The goals and objectives of the CoastWatch Great Lakes Program directly support agency statutory responsibilities in estuarine and marine science, living marine resource protection, and ecosystem monitoring and management. Great Lakes CoastWatch data are used in a variety of ways including monitoring of algal blooms, plumes, ice cover and water temperatures, two and three dmeinsional modeling of Great Lakes pnysical parameters such as wave height and currents, damage assessment modeling, research, and for educational and recreational activities.

LIU, P. C. A fifteen minute introduction of wavelet transform and application. Proceedings, 1999 International Water Resources Engineering Conference, Seattle, WA, August 7-12, 1999. American Society of Civil Engineers, 7 pp. (1999).

This is a very brief introduction on the basic concepts of wavelet transform and its applications. It is certainly not possible to present comprehensive details for wavelets in a short time, only an attempt to interject some underlying features to engineers who are not yet familiarize with wavelet transform on what makes wavelet one of the most exciting useful tools as well as research areas today. Topics introduced include the why, what and how of wavelets, continuous wavelet transforms, time-frequency analysis, stationary and nonstationary processes, and available tools for engineering applications.

LIU, P. C. Is the wind wave frequency spectrum outdated? Ocean Engineering 27:577-588 (1999).

This paper presents a detailed examination of the practice of using the frequency spectrum to characterize wind waves. In particular, the issue of stationarity and Gaussian random process in connection with wind wave studies is addressed. We describe a test for nonstationarity based on the wavelet spectrum. When this test is applied to wind wave time series, the results significantly diverge from those expected for a Gaussian random process, thus casting critical doubts on the conventional concept of the wind wave frequency spectrum.

LIU, P. C. Wave grouping characteristics in nearshore Great Lakes. Ocean Engineering 27:1221-1230 (2000).

The recently advanced approach of wavelet transform is applied to the analysis of wave data measured in the nearshore areas of the Great Lakes. The conventional spectrum analysis of wave time series in the frequency domain can be readily generalized to the frequency and time domain using the wavelet transform. The traditional Fourier transform approach has not been able to directly assess the time localized nature of wave groups. With the application of wavelet transformation, the relatively unexplored wave grouping characteristics come to light as the predominant feature of wave processes.

LIU, P. C. Wavelet transform and new perspective on coastal and ocean engineering data analysis. In Advances in Coastal and Ocean Engineering, P.L-F. Liu (Ed.), World Scientific, Singapore, pp. 57-101 (2000).

Wavelets and wavelet transforms, which were considered novel approaches only a few years ago, have rapidly emerged as common subjects of research and applications in scientific and engineering investigations.

LIU, P. C., and N. Mori. A wavelet transform analysis of freak waves in the ocean. Proceedings, 1999 International Water Resources Engineering Conference, Seattle, WA, August 7-12, 1999. American Society of Civil Engineers, 7 pp. (1999).

A wavelet transform analysis of continuous wave recordings in the Sea of Japan during 1986-1990 is carried out to study the incidents of freak waves. It is found that a well-defined freak wave can be readily identified from the wavelet spectrum where strong energy density in the spectrum is instantly surged and seemingly carried over to the high frequency components at the instant the freak wave occurs. Therefore, for a given freak wave, there appears a clear corresponding signature shown in the time-frequency wavelet spectrum. As freak waves are primarily transient events occurring unexpectedly, an application of wavelet transform analysis on continuous, long duration wave measurements would be the most ideal approach to discern the unexplored characteristics of freak waves.

LOFGREN, B. M. Cloud and vertical resolution issues in the Coupled Hydrosphere-Atmosphere Research Model (CHARM). Proceedings, 14th Conference on Hydrology, American Meteorological Society, Dallax, TX, January 10-15, 1999. American Meteorological Society, pp. 380-383 (1999).

The Great Lakes are important hydrologically because they store 80% of the fresh water in North America and supply water for many municipal, industrial, recreational, and transportation functions. They are also of great meteorological interest because they are strong thermal reservoirs that can induce mesoscale episodic events along their shorelines, and can induce lake-aggregate effects that span a spatial scale that verges into the synoptic scale (e.g. Sousounis 1997). The hydrologic and atmospheric components of the system can interact through budgets ot water and energy in the lakes themselves and the land areas of the surrounding basin.

LOFGREN, B. M. Precipitation, soil, and evaporation validation of the coupled hydrosphere-atmosphere research model. Preprints, 15th Conference on Hydrology, Long Beach, CA, January 9-14, 2000. American Meteorological Society, Boston, MA, pp. 275-278 (2000).

Climate change and its effects on water resources are of concern in a great many regions. Not the least of these is the North American Great Lakes Basin. The water depth within channels, harbors, and marinas can have a great effect on the economic sectors of commercial shipping and recreational boating. The concerns of shoreline residents and for the maintenance of healthy shoreline wetland ecosystems can be affected in different ways by fluctuations and trends in lake level. A number of studies (e.g. Ouinn and Lofgren 2000) have used the output of general circulation models (GCMs) as a driver of local hydrologic models. These have used various means of downscaling the coarse-gridded output of GCMs to the size of drainage basins of interest, but generally have not included two-way interaction in which the lakes are not only affected by the atmosphere, but the atmosphere is also affected by the lakes. Bates et al. (1993, 1995) introduced the concept of running nested regional climate models over the Great Lakes Basin. These works accomplished a proof of concept for this method, but did not apply the method to scenarios such as greenhouse warming. The Coupled Hydrosphere-Atmosphere Research Model (CHARM) is being developed as a regional climate model for the Great Lakes Basin. It is based on the Regional Atmospheric Modeling System (RAMS, version 3a) along with the Large Basin Runoff Model of the Great Lakes Basin, developed at the Great Lakes Environmental Research Laboratory (GLERL), and a vertical diffusion model of lake temperature which also calculates lake evaporation and other surface heat fluxes, also developed at GLERL. Because RAMS was not originaJlydesigned as a model for climate simulation (I.e. for simulation over periods of multiple months or years), some modification was necessary. The subject of this paper is the implementation of a few of these modifications and their effect onthe model's agreement with observed near-surface air temperature and precipitation.

Lotufo, G. R., P. F. LANDRUM, M. L. GEDEON, E. A. TIGUE, and L. R. HERCHE. Comparative toxicity and toxicokinetics of DDT and its major metabolites in freshwater amphipods. Environmental Toxicology and Chemistry 19(2):368-379 (2000).

The toxicity and toxicokinetics of radiolabeled DDT and its major degradation products, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), were determined for the amphipods Hyalella azteca and Diporeia spp. in water-only static renewal exposures. Comparison of the water and tissue concentrations associated with decreased survival revealed large differences in toxicity among the three compounds. In H. azteca, the ratio of the 10-d LR50 values (median lethal tissue residue) for DDT:DDD:DDE was 1:24:195. In Diporeia spp., the 28-d LR50 for DDT was higher than that for DDD by a factor of six, and DDE did not cause sign)ficant mortality even at concentrations approaching the solubility limit. Based on the toxicity data, the hazard from exposure to mixtures of DDT and its degradation products should be evaluated on a toxic-units basis and not as a simple summation of the individual concentrations, which ignores the toxicity of specific compounds. Differences in species sensitivity were also detected. The 10-d LR50 values were higher in Diporeia spp. than in H. azteca by a factor of 40 for DDT and eight for DDD. This difference can be only partly attributed to differences in lipid content between H. arteca (7% dry wt) and Diporeia spp. (24% dry wt). The uptake clearance and elimination rate constants were similar among the various compounds in both species. Uptake clearance was typically fourfold greater for H. arteca than for Diporeia spp., however, and the experimentally measured elimination rate was approximately 30-fold greater in H. azteca than in Diporeia spp. The larger rates of uptake and elimination were attributed to the higher exposure temperature, greater surface area-to-volume ratio, and lower lipid content for H. azteca compared with Diporeia spp. In addition, extensive biotransformation of DDT by H. azteca may have contributed to a more rapid compound elimination.

LOU, J., D. J. SCHWAB, D. BELETSKY, and N. HAWLEY. A model of sediment resuspension and transport dynamics in southern Lake Michigan. Journal of Geophysical Research 105(C3):6591-6610 (2000).

A quasi-three-dimensional suspended sediment transport model was developed and generalized to include combined wave-current effects to study bottom sediment resuspension and transport in southern Lake Michigan. The results from a threedimensional circulation model and a wind wave model were used as input to the sediment transport model. Two effects of nonlinear wave-current interactions were considered in the sediment transport model: the changes in turbulence intensity due to waves and the enhancement of induced bottom shear stresses. Empirical formulations of sediment entrainment and resuspension processes were established and parameterized by laboratory data and field studies in the lake. In this preliminary application of the model to Lake Michigan, only a single grain size is used to characterize the sedimentary material, and the bottom of the lake is treated as an unlimited sediment source. The model results were compared with measured suspended sediment concentrations at two stations and several municipal water intake turbidity measurements in southern Lake Michigan during November-December 1994. The model was able to reproduce the general patterns of high-turbidiby events in the lake. A model simulation for the entire 1994-1995 two-year period gave a reasonable description of sediment erosion/deposition in the lake, and the modeled settling mass fluxes were consistent with sediment trap data. The mechanisms of sediment resuspension and transport in southern Lake Michigan are discussed. To improve the model, sediment class)fications, spatial bottom sediment distribution, sediment source function, and tributary sediment discharge should be considered.

Lydy, M. J., J. L. Lasater, and P. F. LANDRUM. Toxicokinetics of DDE and 2-Chlorobiphenyl in Chironomus tentans. Archives of Environmental Contamination and Toxicology 38:163-168 (2000).

Uptake, biotransformation, and elimination rates for DDE and 2-chlorobiphenyl (2-CB) were examined using fourth instar midge larvae (Chironomus tentans) under a water-only exposure. A two-compartment model that included biotransformation described the kinetics for2-CB and a one-compartment model was used for DDE. The uptake clearance coefficient (ku) was 65.96 +- 2.09 ml • g^-1 midge h ^-1 for 2-CB and 84.1 + 2.7 ml • g^-1 midge h^-1 for DDE. DDE demonstrated no measurable elimination, while 2-CB showed elimination with faster elimination of parent compound (kcp = 0.100 + 0.008 h^-1) compared to the polar metabolites (kem = 0.073 + 0.016 h^-1). The biotransformation rate for 2-CB (km = 0.031 + 0.005 h^-1) appeared to be time-dependent with faster rates at the beginning of the accumulation process slowing to a constant once the midge was loaded with chemical. Experimental results indicate a difference in the ability of C. tentans to eliminate 2-CB and its metabolites more quickly than DDE, and these differences were related to the bioconcentration potential of the compounds.

Magnuson, J. J., D. M. Robertson, B. J. Benson, R. H. Wynne, D. M. Livingstone, T. Arai, R. A. ASSEL, R. G. Barry, V. Card, E. Kuusisto, N. G. Granin, T. D. Prowse, K. M. Stewart, and V. S. Vuglinski. Historical trends in lake and river ice cover in the Northern Hemisphere. Science 289:1743-1746 (2000).

Freeze and breakup dates of ice on lakes and rivers provide consistent evidence of later freezing and earlier breakup around the Northern Hemisphere from 1846-1995. Over these 150 years, changes in freeze dates averaged 5.8 days per 100 years later, and changes in breakup dates averaged 6.5 days per 100 years earlier; these translate to incresing air temperatures of about 1.2^oC per 100 years. Interannual variability on both freeze and breakup dates has increased since 1950. A few longer time series reveal reduced ice cover (a warming trend) begining as early as the 16th century, with increasing rates of change after about 1850.

Mortsch, L., H. Hengeveld, M. Lister, B. M. LOFGREN, F. H. QUINN, M. Slivitzky, and L. Wenger. Climate change impacts on the hydrology of the Great Lakes-St. Lawrence System. Canadian Water Resources Journal 25(2):153-179 (2000).

A review of the current state of knowledge on climate change due to an 'enhanced greenhouse effect' and the response of the climate and hydrologic systems to a changing atmosphere is provided. In particular, the survey presents historic trends in and the impacts of climate change on temperature, precipitation, evapotranspiration, runoff and Great Lakes levels. While much of the impacts research in the Great Lakes-St. Lawrence basin has usud equilibrium 2xCO2 scenarios, the transient scenarios tor 2030 and 2050 from the Canadian Centre for Climate Modelling and Analysis and the United Kingdom Hadley Centre coupled atmosphere-ocean global circulation models are also described. If the significant declines in runoff and lakes levels suggested by climate change scenarios are realized, there could be serious supply-demand mismatches and water allocation issues. The issue of climate change reinforces the need tor continued cooperative planning and management of the water resources ot'the Great Lakes-St. Lawrence basin.

NALEPA, T. F. Changes in mussel populations in the Great Lakes: Native mussels eliminated from Lake St. Clair. Color Brochure, NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 pp. (2000). http://www.glerl.noaa.gov/pubs/brochures/brochures.html

NALEPA, T. F., G. L. FAHNENSTIEL, and T. H. JOHENGEN. Impacts of the zebra mussel (Dreissena polymorpha) on water quality: A case study in Saginaw Bay, Lake Huron. In Non-Indigenous Freshwater Organisms: Vectors, Biology, and Impacts, R. Claudi and J.H. Leach (Eds.), CRC Press, Lewis Publishers, Boca Raton, FL, pp. 255-271 (1999).

Impacts of benthic, suspension-feeders on pelagic measures of water quality (i.e., phytoplankton, water clarity, nutrients) have been well-documented in both freshwater and marine environments (Cloern 1982; Officer et al. 1982; Wright et al. 1982; Cohen et al. 1984; Dame et al. 1991). These organisms filter particles from the water and ingest material that is either assimilated and incorporated into biomass, or rejected and deposited as feces and pseudofeces. As a result, energy is shifted from the pelagic region to the benthic region, and changes occur in the normal pathways by which nutrients are utilized and cycled. Impacts of these feeding activities depend on the characteristics of the particular system, and on the density of the suspension-feeding population. Greatest impacts generally occur in productive, shallow water systems with high population densities. Under these conditions, the population can be capable of filtering water at a time rate constant that is much greater than the water residence time within the system, and at a rate greater than, or comparable to, phytoplankton growth.

NALEPA, T. F., D. J. HARTSON, J. Buchanan, J. F. CAVALETTO, G. A. LANG, and S. J. Lozano. Spatial variation in density, mean size, and physiological condition of the holoarctic amphipod Diporeia spp. in Lake Michigan. Freshwater Biology 43:107-119 (2000).

We examined spatial patterns in population characteristics (density, biomass, mean body length) and physiological condition (lipid content, length-weight) of the amphipod Diporeia spp. in Lake Michigan by collecting samples at up to 85 sites in late summer 1994 and 1995. Variables were examined relative to water depth and three lake regions: south, central and north. Most major river systems are found in the south, and this region is more nutrient-enriched compared to the north. Over all sites, mean density was 5240 m-2, biomass was 4.1 g dry wt m-2, and mean body length was 5 mm. While maximum densities were related to depth, with a peak at 30-70 m, greatest densities occurred on the west side of the lake, and low densities were found in the south-east, north-east and lower Green Bay. High densities in the west probably resulted from upwelling, and reduced densities in the south-east may reflect food competition with Dreissena polymorpha (zebra mussel). Lipid content, weight per unit length, and mean length declined with increased water depth, but depth-related trends were most evident in the south. Overall, mean lipid content and weight per unit length were significantly lower in the south (16.6% dry wt, 0.59 mg at 5 mm body length) compared to the north (23.7% dry wt, 0.78 mg at 5 mm body length). These regional differences may have resulted from greater diatom availability in the north and competition from D. polymorpha in the south. Triacylglycerols and phospholipids were the dominant lipid classes in all three regions. Although the mean proportion of triacylglycerols, the energy-storage lipid, was lower in the south than in the north, regional differences in proportions of lipid classes were not sign)ficant. Mean lipid content and weight per unit length of Diporeia in the south were lower than values found in the late 1980s prior to the establishment of Dreissena. Mean lipid content of mature individuals is now at levels considered a minimum for successful reproduction.

NORTON, D. C., R. A. ASSEL, D. MEYERS, B. A. HIBNER, N. MORSE, P. J. TRIMBLE, K. CRONK, and M. RUBENS. Great Lakes ice data rescue project. NOAA Technical Memorandum GLERL-117, NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (NTIS# not yet available) 63 pp. (2000). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-117

Great Lakes ice cover is important because it affects the aquatic system of the Great Lakes (Lam and Schertzer,1999; Magnuson et al.,1997), the regional weather (Petterssen and Calabrese,1959; Sousounis,1997),and the regional economy. In an earlier project, over 2800 historical ice charts spanning the winters of 1960-1979 were digitized (Assel, 1983). The project described here updates that earlier Great Lakes ice cover data base,with the following important differences: (1) the ice charts digitized contain some extrapolated data and cover the entire surface area of the Great Lakes;the earlier ice charts did not cover the entire surface of the Great Lakes and contained original observations only, (2) the updated data base contains information on ice concentration, ice age (thickness)and ice form (flow size); the earlier ice cover data base only contains information on ice concentration, and (3) the earlier data base has a spatial precision of 5 km, the updated data base has a spatial precision of 2.56 km. This project has its origins in the Environmental Research Laboratories’ Endangered Data and Increased Access Program, and NOAA’s National Environmental Satellite and Data Information Service’s (NESDIS)Earth System Data and Information Management (ESDIM) Program. The purpose of this report is to document the methods and procedures used to update the ice cover database. The methods and computer algorithms described here may serve a secondary purpose:to provide guidance to others in researcher, academia,and private industry who have developed, or plan to develop, similar projects to digitize historical graphically based data sets. The objective of the project was to develop an updated ice cover data set.These data will then be used to update the existing Great Lakes Ice Atlas, Assel et al. (1983) and to provide historical ice cover data in an electronic form to make it more easily accessible for others (researchers, operational users, private industry, and to the public at large) who have need of such data in their applications. The general Standard Operating Procedure (SOP) for digitizing ice charts,quality control of the digital data, and interim and final products is summarized in the main body of this report. Additional information of a technical nature with much greater detail of the step-by-step procedures and computer algorithms are given in a series of appendices for those interested in the ‘nuts and bolts’ of the SOP. The SOP along with the appendices provides the user with a synergistic encapsulation of this project.

Pakulski, J. D., R. Benner, T. Whitledge, R. Amon, B. J. EADIE, L. Cifuentes, J. Ammerman, and D. Stockwell. Microbial metabolism and nutrient cycling in the Mississippi and Atchafalaya River plumes. Estuarine, Coastal and Shelf Science 50:173-184 (2000).

Spatial distributions of chlorophyll, bacterial abundances and production, community respiration, and dissolved C, N, P and Si were measured in the Mississippi River (MRP) and Atchafalya River (ARP) plumes during July 1993. Dark bottle incubations were used to estimate net flux rates of inorganic nunients, community respiration, and changes in chlorophyll concentrations in unfiltered water samples. Concenuranons of total dissolved N (TDN) and soluble reactive P (SRP) in the Mississippi River were 55 M and 3 M higher, respectively, compared with those in the Atchafalaya River. Concenurations of dissolved organic carbon (DOC) and nitrogen (DON) in the Atchafalaya River, however, were 35 and 11 M higher, respectively than in the Mississippi River. Elevated chlorophyll concentrations, bacterial abundances and production, and community respiration rates were observed at intermediate (5-25) salinities of both plumes. Propertysalinity plots indicated net sinks of dissolved N, P and Si at intermediate salinities consistent with photosynthetic utilization of these substances within the plumes. The distribution of dissolved P, N and chlorophyll suggested phytoplankton-mediated transformation of riverine-NO₃ to DON at intermediate salinities of the MRP, and a similar transformation of riverine SRP to dissolved organic P (DOP) at intermediate salinines of the ARP. Net regeneration of dissolved Si and NH4 was observed in regions of elevated chlorophyll concenurations and net removal rates in both plumes. Nitrification rates in the MRP were c. 10-fold higher than in the ARP. Estimates of C fixation by nitrifying bacteria equalled or exceeded heterourophic bacterial C production in the low salinity region of the MRP, but were negligible compared to heterotrophic bacterial production in the ARP. Dissolved inorganic N:P, Si:P and DOC:DON:DOP ratios suggested the potential for P limitation in both plume systems during the period investigated.

POTHOVEN, S. A., T. F. NALEPA, and S. B. BRANDT. Age-0 and age-1 yellow perch diet in southeastern Lake Michigan. Journal of Great Lakes Research 26(2):235-239 (2000). http://www.glerl.noaa.gov/pubs/fulltext/2000/20000006.pdf

Age-0 yellow perch (Perca flavescens) were collected during October 1998 and age-1 yellow perch were collected during June 1999 from southeastern Lake Michigan off St. Joseph and Muskegon, Michigan, to evaluate diets relative to recent ecosystem changes. Size range of yellow perch examined was 72 to 118 mm. In October at a 15-m site off Muskegon, both Gammarus spp. and Isopoda were found in nearly 71% of age-0 yellow perch stomachs, and accounted for 71 and 26% of the diet by weight respectively. The following spring at the 15-m site (June 1999), Gammarus spp. and Isopoda were only a small part of age-l yellow perch diet, and Chironomidae and Mysis relicta dominated the diet. In October at depths of 25 to 35 m, M. relicta, was found in 100 and 80% of the age-0 yellow perch containing food off Muskegon and St. Joseph, respectively, and comprised over 96% of the diet by weight. Gammarus spp., Isopoda, and M. relicta were eaten in higher numbers than would be expected based on their low abundance in the environment. The high occurrence of Gammarus spp. and Isopoda in yellow perch diet may indicate ongoing changes in the nearshore benthic community.

POTHOVEN, S. A., B. Vondracek, and D. L. Pereira. Effects of vegetation removal on Bluegill and Largemough Bass in two Minnesota lakes. North American Journal of Fisheries Management 19:748-757 (1999).

Abundance and growth of bluegill, Lepomis macrochirus, diet and growth of largemouth bass, Micropterus salmoides, and abundance of age-0 largemouth bass were evaluated in two treatment and three reference lakes in Minnesota to assess the effects of whole-lake herbicide treatments. Lakes were evaluated 1 year prior (1993), during (1994), and after (1995) treatment. In reference lakes, vegetation, fish growth, abundance, and diet remained relatively unchanged throughout the study. Herbicide applications in May 1994 decreased the percentage of sampling stations with vascular vegetation from 100% to 33% in Parkers Lake and 63% in Zumbra Lake betvveen August 1993 and 1994. Vegetation returned to some areas of Parkers Lake in 1995 (77%) but continued to decline in Zumbra Lake (43%). Purse-seine catch per effort (CPE) of small bluegill (60-100 mm) decreased following treatment but returned to pretreatment levels the following year, whereas CPE of large bluegill (> 100 mm) increased in 1994 in trap nets and remained constant in gill nets and large bag seines. Age-0 largemouth bass abundance was not affected by vegetation removal. Growth of bluegills and largemouth bass was greater in 1994 than in the previous 4-5 years. Largemouth bass stomachs contained more fish prey and were empty in fewer instances only during 1994 in Zumbra Lake. Because few treatment effects were sustained during the posttreatment year, whole-lake treatments with herbicide may not be a useful tool for longterm management of bluegills or largemouth bass unless annual or semiannual treatments are an acceptable social, biological, and economic strategy.

QUINN, F. H. Low water: should we get used to it? In Great Lakes SeaWay Review, Volume 29, Number 1, Harbor House, Great Lakes Seaway Review, Boyne City, MI, pp. 33-35 (2000).

The precipitous drop in Great Lakes water levels experienced over the past two years has had widespread impact within the basin, economically and otherwise. Is this a short-lived phenomenon, or portentous of a new, long term regime?

QUINN, F. H., and T. E. CROLEY II. Potential climate change impacts on Lake Erie. In State of Lake Erie (SOLE) Past, Present and Future, M. Munawar, T. Edsall and I. F. Munawar, Backhuys Publishers, Leiden, The Netherlands, pp. 23-30 (1999).

Lake Erie is one of the most intensively used large freshwater lakes in the world serving multiple interests including fisheries, navigation, ydropower, riparian, and recreation. In addition, its present aquatic and coastal ecosystems have developed based upon a fairly stable climate. Scenarios of global warming and changed climate variability have indicated a number of potentially significant impacts of a changing climate on Lake Erie's ecosystem and interests. Impacts include higher air and water temperatures, increased precipitation, decreased riverine runoff, decreased snowfall and snowpack accumulation, decreased ice cover, increased evapotranspiration, and a major reduction in lake levels and connecting channel flows. These impacts would affect the quantity and quality of wetland and aquatic habitats, change the timing of lake turnover resulting in increased anoxia and a changed fish community composition and dynamics.

QUINN, F. H., and B. M. LOFGREN. The influence of potential greenhouse warming on Great Lakes hydrology, water levels, and water management. Preprints, 15th Conference on Hydrology, Long Beach, CA, January 9-14, 2000. American Meteorological Society, Boston, MA, pp. 271-274 (2000).

The Great Lakes are one of North America's largest water resource systems with a basin area of about 770,000 km2. It is one of the most intensively used fresh water systems in the world, serving multiple interests including navigation, hydropower, recreation, water supply, food supply, and riparian. Great Lakes water levels change slowly due to the large lake surface areas and constricted outlet channels, which integrate short-term climate fluctuations. Because the Great Lakes have historically had a very limited range in water levels, the impacts of potential climate change are significant. As part of the U.S. National Climate Change Assessment, estimates were made of changes in net basin water supply (precipitation plus runoff minus lake evaporation) for the drainage basin of the Laurentian Great Lakes due to the influence of increased greenhouse gases. Data generated by general circulation models from the Canadian Climate Centre, CGCM1, and the Hadley Centre, HadCM2, were used to make adjustments to observed data for temperature, precipitation, cloud cover, relative humidity, and wind speed. The adjusted and unadjusted data were then used to drive a system of rainfall/runoff, lake evaporation, hydrologic routing, and water management models for the Great Lakes system to assess hydrologic and water management changes.

REID, D. F., and G. A. Meadows. Proceedings of the Workshop The Environmental Implications of Cargo Sweeping in the Great Lakes. NOAA Technical Memorandum ERL GLERL-114. Great Lakes Environmental Research Laboratory, Ann Arbor, MI, (NTIS # not yet available) 66 pp. (1999). ftp://ftp.glerl.noaa.gov/publications/tech_reports/glerl-114

"Cargo sweeping" is the practice of removing the residues of dry bulk cargoes, such as iron ore, coal, grain, and various rock materials, from the deck and holds of cargo vessels. Such residues occur after most loading or unloading operations. Cleanup is accomplished by washing the decks and cargo spaces with water, which is then discharged over the side, usually while underway. Coast Guard regulations proposed in 1989 would have made the discharge of cargo residues illegal on the Great Lakes, which would have disrupted the continued operations of the U.S. Great Lakes shipping industry. In September 1994 a workshop was held to identify the research needed to provide a scientific basis for regulatory decisions. Three separate work groups, Risk to Fisheries & Habitat, Sediment Accumulation & Toxicity, and Water Column Impacts, were convened. Each group was asked to consider and identify what we already know and what gaps there are in our knowledge and understanding related to cargo sweeping, what further information or studies are needed, and how best to obtain the requisite information.
- All three groups identified the need for comprehensive information on the composition of the commodities, especially relative to impurities and added chemicals that might prove environmentally harmful. Such information should be obtained by literature searches and direct analyses of the composition.
- Each group indicated the need for studies to determine the bioavailability and bioaccumulation of cargo components and impurities that may be toxic.
- Each group identified a series of other information gaps and questions in need of answers, and recommended various approaches to obtain needed information.

Richardson-Heft, C. A., A. A. Heft, L. Fewlass, and S. B. BRANDT. Movement of Largemouth Bass in Northern Chesapeake Bay: Relevance to sportfishing tournaments. North American Journal of Fisheries Management 20:493-501 (2000).

Largemouth bass Micropterus salmoides have been displaced as far as 50 km from where they were caught in Chesapeake Bay tidewater angling tournaments. Two concerns are whether largemouth bass return to capture areas or whether they stockpile at tournament release sites. To answer these questions, movements of 82 largemouth bass tagged with radio transmitters and 146 largemouth bass tagged with streamer tags were observed during 1991-1995. Fish were collected by boat electrofishing near two disparate tournament weigh-in stations on the eastern and western shores of northern Chesapeake Bay. Some largemouth bass (43 radio-tagged, 58 streamer-tagged) were displaced 15-21 km to the other station; controls (39 radio-tagged, 88 streamer-tagged) were released where they were caught. Movement patterns were similar for displaced largemouth bass: 43% from the Susquehanna River (western shore) and 33% from the Northeast River (eastern shore) exhibited directed movement towards initial capture areas by returning to their original capture areas. Among the controls, only 4% of Susquehanna River and 6% of Northeast River fish traveled to the opposite shore, demonstrating that return movement was not random. For displaced bass that returned to original capture areas, those released in the spring tended to return within 3 months, whereas bass released in the fall returned within 7-12 months. For both groups, this typically occurred when water temperatures were between 12.0°C and 22.5°C. Most radio-tagged largemouth bass (64%) were located more than 0.5 km from their release sites (i.e., the designated stockpiling zone) 7 d after release. The final located positions for radio-tagged largemouth bass averaged 9.6 km from the release sites, and 95% were at least 0.5 km from the release sites. Results from our study demonstrate that displaced largemouth bass tend to return to their capture areas and that short-term stockpiling of largemouth bass at tournament release areas was possible, but that long term stockpiling did not occur.

RUBERG, S. A., and B. J. EADIE. Remotely deployable water sampler. Proceedings, Oceans 2000 Marine Technology Society/IEEE Conference, Providence, RI, September 12, 2000. Marine Technology Society, Washington, DC, pp. 113-117 (2000).

Episodic events can exert major influences on ecosystems. Paradoxically, it is during these major events when it is least possible to collect samples from ships, thus unreliable extrapolations of system dynamics have been made, In order to collect samples for constituent analyses during these critical times, a remotely deployable water sampler has been designed, built, and is currently being tested by NOAA/GLERL in Lake Michigan to meet this need. The system can be configured to sample from various depths and has the capacity to collect up to 24 discrete, one-liter samples. Individual samples are collected based on a programmed schedule driven by a real-time clock or will be collected based on external events such as changes in temperature, turbidity, fluorescence, or wave height.

SCHWAB, D. J., and K. W. Bedford. The Great Lakes Forecasting System. In Coastal Ocean Prediction, Coastal and Estuarine Studies 56, C.N.K. Mooers (Ed.), American Geophysical Union, Washington, DC, pp. 157-173 (1999).

The Great Lakes Forecasting System is a coastal forecasting system designed to make nowcasts and two day forecasts of the important physical parameters for each lake including water levels, waves, currents, and temperatures. Observed and forecast surface meteorological data are used as input to a three dimensional circulation model and a parametric wave prediction model. Output includes maps of physical parameters in computer-readable form. The system is currently operational for Lake Erie. This chapter describes system design, data acquisition and analysis, the hydrodynamic model, products, and evaluation of results.

SCHWAB, D. J., D. BELETSKY, and J. LOU. The 1998 Coastal turbidity plume in Lake Michigan. Estuarine, Coastal and Shelf Science 50:49-58 (2000).

In this paper, numerical models of coastal circulation, wind-waves, and sediment transport are applied to the March 1998 turbidity plume event in Lake Michigan to investigate the role of wind-induced circulation in the offshore transport of sedimentary material in Lake Michigan. Computer visualization is used to compare model results to the evidence of cross-isobath transport suggested in satellite imagery. Model results showed that circulation in Lake Michigan is highly episodic since it is almost entirely wind-driven in early spring. The characteristic wind-driven circulation pattern in the lake consists of two counter-rotating gyres, a counterclockwise-rotating gyre to the right of the wind, and a clockwise-rotating gyre to the left. The gyres are separated by a convergence zone along the downwind shore with resulting offshore flow and a divergence zone along the upwind shore with onshore flow. This two-gyre circulation pattern with offshore flow was very clearly seen during a northerly wind event in March 1998 in southern Lake Michigan. The strongest sediment resuspension occurred in the southern lake and the shallow waters along the coastline. This is because of the larger waves in southern Lake Michigan due to the dominant northerly wind in this early spring period. The two most significant sediment resuspension events were detected in the model results during the two storm events. Although results from the sediment transport model agree qualitatively with satellite imagery, they fail to simulate the initial eddy-like structure of the plume. Visualization is shown to be an effective tool for interpreting the complex turbidity patterns in the satellite imagery of the turbidity plume.

SCHWAB, D. J., G. A. LANG, K. W. Bedford, and Y. F. P. Chu. Recent developments in the Great Lakes Forecasting System (GLFS). Preprints, Third Conference on Coastal Atmospheric and Oceanic Prediction and Processes, New Orleans, LA, November 3-5, 1999. American Meteorological Society, Boston, MA, pp. 201-206 (1999).

The Great Lakes Forecasting System (GLFS) is a real-time coastal prediction system that was developed for daily forecasting of surface water tevel fluctuations, horizontal and vertical structure of temperature and currents, and wind waves in the Great Lakes (Schwab and Bedford, 1994). The system uses surface meteorological observations and forecasts from numerical weather prediction models as input. Lake circulation and thermal structure are calculated using a three-dimensional hydrodynamic prediction model (Blumberg and Mellor, 1987). Wind waves are calculated with a parametric wave prediction model (Schwab et al., 1984). Output from the models is used to provide information on the current state of the lake and to predict conditions for the next several days. A full report on the status of the system was presented at the 1996 Conference on Coastal Oceanic and Environmental Prediction (Schwab and Bedford, 1996).

SCHWAB, D. J., G. A. LESHKEVICH, and G. C. MUHR. Automated mapping of surface water temperature in the Great Lakes. Journal of Great Lakes Research 25(3):468-481 (1999). http://www.glerl.noaa.gov/pubs/fulltext/1999/19990006.pdf

A procedure for producing daily cloud-free maps of surface water temperature in the Great Lakes has been developed. It is based on satellite-derived AVHRR (Advanced Very High Resolution Radiometer) imagery from NOAA's CoastWatch program. The maps have a nominal resolution of 2.6 km and provide as complete as possible coverage of the Great Lakes on a daily basis by using previous imagery to estimate temperatures in cloud covered areas. Surface water temperature estimates derived from this procedure compare well with water temperatures measured at the eight NOAA weather buoys in the lakes. The mean difference between the buoy temperature and the satellite-derived temperature estimates is less than 0.5°C for all buoys. The root mean square differences range from 1.10 to 1. 76°C. As one example of the possible applications of this product, the daily surface water temperature maps for 1992 to 1997 were analyzed to produce daily estimates of average surface water temperature for each lake. Results are compared to the long-term (28 year) mean annual cycle of average surface water temperatures. The average surface water temperatures vary from as much as 4°C below climatology in 1993 to 2 to 3°C above climatology in 1995. The new analysis procedure also provides a more realistic depiction of the spatial distribution of temperature in the springtime than the climatological maps.

Simenstad, C. A., S. B. BRANDT, A. Chalmers, R. Dame, L. A. Deegan, R. Hodson, and E. D. Houde. Habitat-biotic interactions. In Estuarine Science: A Synthetic Approach to Research and Practice, J.E. Hobbie (ed.), Island Press, Washington, DC, pp. 427-455 (2000).

Conventional concepts of estuarine and near-shore coastal habitac are generally inadequate descriptions of processes and organisms that respond to habitat variability and change or integrate far larger and more complex "habitat landscapes." In particular, the role of structure within and among habirats, networks through which organisms and critical processes that influence secondary production operate, and the role of estuarine circulation "control point" features in shaping food-web structure and variability are poorly known. In response to these gaps, the Habitat-Biotic Interactions Working Group established as their goal to identify approaches needed to synthesize a mechanistic understanding of how habitat structure influences estuarine secondary production and food web. We recommend eight major steps to enhance synthesis of natural and anthropogenic changes in estuarine production related to habitat-biotic interactions: (1) develop an estuarine habitat classification scheme that relates habitat structure to estuarine producrion and food-web processes; (2) examine existing long-term data sets to identify the scope and frequency of variability in habitat strucuire; (3) implement comparative studies of habitat function; (4) develop and link habitat and landscape models that capture the dynamics of biota and process interactions over large estuarine scales; (5) develop indicators of ecosystem habitat integrity, dynamics, and variability; (6) link site-specific field experiments and modeling approaches to scale processes and process understanding across ecosystems and landscapes; (7) apply advanced measurement technologies to give details of distributions and abundances of secondary consumers not now achievable; and (8) link habitat structure to assessment and prediction of resource management scenarios. Addressing ecosysrem change in response to habitat structure, as well as the impacts of coastal zone managemenr impacts upon ecosystems will require innovative syntheses at much more expanded time and space scales than heretofore considered.

Virden, W., J. Warren, T. Holcombe, D. REID, and T. Berggren. Bathymetry of Lake Ontario. A color poster with descriptive text. U.S. Dept. of Commerce, NOAA, National Geophysical Data Center, Boulder, CO, (Data Announcement 2000-MGG-01) (1999). http://www.ngdc.noaa.gov/mgg/mggd.html

Walline, P. D., J. A. TYLER, S. B. BRANDT, I. Ostrovsky, and J. M. JECH. Lavnun abundance: how changes may affect consumption of Lake Kinneret zooplankton. Arch. Hydrobiol. Spec. Issues Advances in Limnology 55:493-511 (2000).

The Israeli Water Commissioner has subsidized the removal from Lake Kinneret of lavnun, the endemic cyprinid Acanthobrama terraesanctoe, since the 1994-1995 fishing season. One of the rationales for the removal program is that reduced consumption of zooplankton by lavnun will increase production of zooplankton and their subsequent consumption of phytoplankton. Here, we use acoustic measures of fish population distribution and abundance, and bioenergetic and spatial modeling to assess the effect of lavnun removal on potential consumption of zooplankton in Lake Kinneret. Two lakewide acoustic surveys were made (in April and June 1998) with a dual-beam acoustic system to measure the fish population. On each survey a salinity and temperature profiler was used to measure the water temperature field in the lake. We used these data and spatially explicit bioenergetic models to determine potential consumption by fish. The size distribution and abundance of the measured fish population were manipulated to calculate potential consumption under various scenarios. Geostatistical interpolation of spatial models provided lakewide measures of fish abundance and potential consumption. Our analysis suggests that the lavnun dilution program has the desired effect of substantially reducing potential zooplankton consumption by lavnun. Further, model scenarios indicated that targeting smaller fish in the removal program could produce an even greater decrease in potential zooplankton consumption than that so far achieved by either the dilution program or by commercial fishing.

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