GLERL Publication Abstracts: FY 2003

ASSEL, R. A. An Electronic Atlas of Great Lakes Ice Cover, Winters 1973-2002. NOAA Atlas. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 CD-ROM Set or DVD pp. (2003).

This NOAA Atlas updates a previous atlas published in 1983. It contains a 30-winter set of original digitized ice charts (Vol. 1) and analysis products (Vol. 2). Further documentation and description of the dataset, analysis methods and products will supplement this atlas as a series of reports. The first report in that series, describing the original data set, is included here.

ASSEL, R. A. Great Lakes ice cover, first ice, last ice, and ice duration. NOAA Technical Memorandum GLERL-125. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 49 pp. (2003).

A 30-winter digital ice cover data set consisting of 1210 ice charts was established for the Great Lakes. The data set is an update of a 28-winter data set given in Assel et al. (2002). The temporal and spatial distribution patterns of the dates of first ice, dates of last ice, and ice duration over the 30-winter base period are analyzed for the combined Great Lakes and for each Great Lake over the 30-winter period. Average and the composite extremes over the 30 winters are presented. Analysis methods are described, and results are summarized in a series of plots, charts, and tables. The complete data set is available as part of an official National Oceanic and Atmospheric Administration Atlas (Assel, 2003).
ASSEL, R. A. Great Lakes ice cover - winter 2003 compared with GLERL's 30-winter ice cover climatology. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 1 pp. (2003).
The extent of Great Lakes ice cover on March 6, 2003 (top figure) is much greater than the normal defined by GLERL’s 30-winter median ice cover climatology (bottom figure). Lakes Superior, Huron, and Erie all have ice covers in excess of 90%. The last time that happened was during the winter of 1996.
ASSEL, R. A., K. CRONK and D. C. NORTON. Recent trends in Laurentian Great Lakes ice cover. Climatic Change 57:185-204 (2003).
A 39-winter (1963­2001) record of annual maximum ice concentration (AMIC), the maximum fraction of lake surface area covered by ice each year, is analyzed for each Great Lake. Lake Erie has the largest median AMIC (94%) followed by Lakes Superior (80%), Huron (63%), Michigan (33%), and Ontario (21%). The frequency distribution of AMICs is negatively skewed for Lakes Superior and Erie and positively skewed for Lakes Michigan and Ontario. Temporal and spatial patterns of typical and extreme AMICs is presented within the context of long-term average air temperatures and lake bathymetry. The variation of spatially averaged ice concentration with discrete depth ranges are discussed for each lake for the upper and lower end of the typical range of AMIC values. In general, ice concentration decreases with increasing depth ranges for a given winter. A decrease in the gradient of ice concentration with depths was also observed with an increase in the AMIC from winter 1983 to winter 1984. A temporal trend in the AMICs supports the hypothesis of three ice cover regimes over the past 39 winters. Approximately 44% of the highest quartile (10 highest) AMICs for the Great Lakes occurred during the 6-winter period: 1977­1982 providing evidence of a higher ice cover regime during this period relative to the 14 winters before them (1963­1976) and the 19 winters after them (1983­2001). Winter 1998 established new low AMIC extremes, and the AMIC averaged over the 1998­2001 winters is the lowest for the period of record on four of the five Great Lakes. These recent trends taken together are noteworthy as they may be harbingers of a period of even lower AMICs in the 21st Century.
ASSEL, R. A. and D. C. NORTON. Twentieth century trends in the ice cover of the Laurentian Great Lakes of North America. Ice in the Environment: Proceedings of the 16th IAHR International Symposium on Ice, Dunedin, New Zealand, December 2-6, 2002. International Association of Hydraulic Engineering and Research, 321-327 pp. (2002).
Trends in the annual maximum ice cover (i.e. the greatest fraction of the total surface area that is ice covered each winter) of the combined area of the five Laurentian Great Lakes of North America are analyzed over the 20th century. The extreme winters of anomalously low and anomalously high annual maximum ice cover extent over the past four decades are identified. An air temperature regression model of ice cover is used to reconstruct annual maximum ice cover over the first six decades of the 20th Century. Cumulative normalized and 5-year running averages of the annual maximum ice cover illustrate variations and trends in the ice cover regime over the 20th Century. Trends and variations are discussed within the context of a recent sequence of five consecutive mild winters.
BELETSKY, D., D. J. SCHWAB, R. P. Roebber, M. J. McCORMICK, G. S. MILLER and J. H. SAYLOR. Modeling wind-driven circulation during the March 1998 sediment resuspension event in Lake Michigan. Journal of Geophysical Research 108(C2):20-1 to 20-13 (2003).
A three-dimensional primitive equation numerical ocean model was applied to Lake Michigan to simulate hydrodynamic conditions during the March 1998 sediment resuspension event in southern Lake Michigan caused by a storm with winds up to 20 m/s. The hydrodynamic model is driven with surface winds derived from observed meteorological conditions at 18 land stations and a meteorological buoy and also with surface winds calculated using a mesoscale meteorological model. Current observations from 11 subsurface moorings showed that the model driven with observed winds was able to qualitatively simulate wind-driven currents but underestimated current speeds during the most significant wind event. In addition, a pronounced offshore flow in the area of observations was also underestimated. Hydrodynamic model results using the meteorological model winds as the forcing function showed significant improvement over model results which were based on observed winds proving the importance of mesoscale winds for current modeling in large lakes.
BRANDT, S. B. Editorial. A bold step forward: ecosystem forecasting, integrated observing systems, and International Field Years for the Great Lakes. Journal of Great Lakes Research 29(3):373-374 (2003).
By any measure, the Laurentian Great Lakes are one of the earth's greatest treasures and the Nation's single most important aquatic resource from an economic, geographic, international, ecological, and societal perspective. Many, increasingly complex challenges lie ahead for the Great Lakes. The Great Lakes continually face extremes in natural phenomena such as storms, erosion, high waves, high and low water levels, and climate variability. Further population growth will lead to an increase in conflicting user demands and complexity in management issues. The one thing that we can predict with near certainty is that the Great Lakes ecosystem will continue to change and the challenges for effective use and management will only increase. We should ask ourselves: Is the scientific and management community ready to meet these long-term challenges?
BRANDT, S. B. and D. M. MASON. Effect of nutrient loading on Atlantic Menhaden (Brevoortia tyrannus) growth rate potential in the Patuxent River. Estuaries 26(2A):298-309 (2003).
We linked a 2-dimensional water quality model of the Patuxent River with a spatially-explicit model of fish growth to simulate how changes in land use in the Patuxent River Basin would affect the growth rate potential (GRP) of Atlantic menhaden (Brevoortia tyrannus). Simulations of three land-use patterns that reflected current nutrient loadings, increased nutrient loadings, and decreased nutrient loadings were used to drive the water quality model. Changes in nutrient loadings caused changes in the timing and intensity of phytoplankton concentrations and the region of hypoxia increased during summer with increased nutrient loading. The spatial distribution of menhaden GRP was highly correlated with phytoplankton concentrations and localized in the middle one third of the Patuxent River. Menhaden growth rate was highest in early June and late summer. During June, menhaden GRP (and phytoplankton concentration) was lowest at the lower nutrient loading simulation. During late summer, mean menhaden growth rates were inversely pro-portional to nutrient loading rates and menhaden grew best when nutrient loadings were the lowest. Upriver to mid-river phytoplankton patches drove overall mean calculations. Model results suggest that more research is needed on water quality model predictions of phytoplankton levels at a high level of spatial and temporal resolution, menhaden foraging, and menhaden habitat selection.
Burton, G. A. and P. F. LANDRUM. Toxicity of sediments. In Encyclopedia of Sedments and Sedimentary Rocks. M. J. C. G.V. Middleton, M. Corigilo, L.A. Hardie, and F.J. Longstaffe (Eds.). Kluwer Academic Publishers, Dordrecht, 748-751 (2003).
As water quality has improved over the past three decades in North America, diffuse sources of pollution such as stormwater runoff and sediments are now recognized as long-term, widespread pollutant sources to aquatic systems. Substantial impacts on the ecosystem from sediment-associate contaminates ranage from direct effects on benthic communities to substantial contributions to contaminant loads and effects on upper trophic levels through food chain contamination (e.g., McCarty and Secord, 1999).
CAVALETTO, J. F., T. F. NALEPA, D. L. FANSLOW and D. W. Schloesser. Temporal variation of energy reserves in mayfly nymphs (Hexagenia spp.) from Lake St. Clair and western Lake Erie. Freshwater Biology 48:1726-1738 (2003).
1. We analysed changes in energy reserves (lipid and glycogen) and length­weight relationships of burrowing mayflies (Hexagenia spp.) in 1997­99 to compare an established population in Lake St Clair with a recovering population in western Lake Erie of the Laurentian Great Lakes. In addition, we measured changes in water temperature and potential food in both water columns and sediments.
2. Although overall mean values of lipid and glycogen levels of Hexagenia nymphs from Lake St Clair and western Lake Erie were not significantly different, there were differences in seasonal patterns between the two lakes. In Lake St Clair, levels were highest in early spring, declined throughout the year, and reached their lowest levels in fall during all 3 years of study. In contrast, levels in western Lake Erie were lower in spring, increased to a maximum in summer, then declined in fall. Seasonal patterns in length­weight relationships were similar to those for lipid and glycogen.
3. Total lipid as a percentage of dry weight did not increase with developmental stage of nymphs until just prior to metamorphosis and emergence from water. However, the major reserve lipid, triacylglycerols, increased systematically with development stage. In the final stage of development, triacylglycerols declined, probably as a result of energy consumption and its conversion to other biochemical components for metamorphosis and reproduction.
4. Indicators of potential food (algal fluorescence in the water column and chlorophyll a and chlorophyll a/phaeophytin ratio in sediments) suggest that Hexagenia in Lake St Clair have a food source that is benthic based, especially in early spring, whereas in western Lake Erie nymphs have a food source that is water column based and settles to the lake bottom during late spring and summer.
CLITES, A. H. and F. H. QUINN. The history of Lake Superior regulation: implications for the future. Journal of Great Lakes Research 29(1):157-171 (2003).
Lake Superior outflows have been regulated for the past 80 years. Lake Superior outflows have been regulated for the past 80 years. The last 15 years have encompassed both extremely high water supplies and lake levels and subsequent drastic declines in the levels of Lakes Superior and the lower lakes. The IJC is considering a study whose purpose would be the reexamination of the current Lake Superior regulation plan, which has been in use since 1990. In preparation for that discussion, several different aspects of past and potential future Lake Superior levels were analyzed. The stage-discharge equation representing natural flow conditions for the pre-1900 Lake Superior outlet was used to simulate "unregulated" Lake Superior outlet conditions, using actual water supplies. Net basin supplies developed for a climate change study were used to evaluate the potential effects of regulation on future levels. A 50,000 year set of stochastic net basin supplies, based upon the present climate, was also used to provide hypothetical upper and lower bounds. By comparing recorded Lake Superior levels to what might have happened in the absence of regulation and what may occur with future supplies, it is hoped that the development and/or evaluation of any future adjustments to the regulation criteria for Lake Superior might be aided.
Cook, P. M., J. A. ROBBINS, D. D. Endicott, K. Lodge, P. D. Guiney, M. K. Walker, E. W. Zabel and R. E. Peterson. Effects of Aryl Hydrocarbon receptor-mediated early life stage toxicity on Lake Trout populations in Lake Ontario during the 20th Century. Environmental Science and Technology 37(17):3864-3877 (2003).
Lake trout embryos and sac fry are very sensitive to toxicity associated with maternal exposures to 2,3,7,8-tetrachlorodibenzo -p-dioxin (TCDD) and structurally related chemicals that act through a common aryl hydrocarbon receptor (AHR)-mediated mechanism of action. The loading of large amounts of these chemicals into Lake Ontario during the middle of the 20th century coincided with a population decline that culminated in extirpation of this species around 1960. Prediction of past TCDD toxicity equivalence concentrations in lake trout eggs (TECeggs) relative to recent conditions required fine resolution of radionuclide-dated contaminant profiles in two sediment cores; reference core specific biota-sediment accumulation factors (BSAFs) for TCDD-like chemicals in lake trout eggs; adjustment of the BSAFs for the effect of temporal changes in the chemical distributions between water and sediments; and toxicity equivalence factors based on trout early life stage mortality. When compared to the dose response relationship for overt early life stage toxicity of TCDD to lake trout, the resulting TECeggs predict an extended period during which lake trout sac fry survival was negligible. By 1940, following more than a decade of population decline attributable to reduced fry stocking and loss of adult lake trout to commercial fishing, the predicted sac fry mortality due to AHR-mediated toxicity alone explains the subsequent loss of the species. Reduced fry survival, associated with lethal and sublethal adverse effects and possibly complicated by other environmental factors, occurred after 1980 and contributed to a lack of reproductive success of stocked trout despite gradually declining TEC eggs. Present exposures are close to the most probable no observable adverse effect level (NOAEL TEC egg ) 5 pg TCDD toxicity equivalence/g egg). The toxicity predictions are very consistent with the available historical data for lake trout population levels in Lake Ontario, stocking programs, and evidence for recent improvement in natural reproduction concomitant with declining levels of persistent bioaccumulative chemicals in sediments and biota.
CROLEY, T. E. II. Weighted-climate parametric hydrologic forecasting. Journal of Hydrologic Engineering:171-180 (2003).
The paper briefly summarizes an existing nonparametric method for using meteorology probability forecasts in operational hydrology and extends it for parametric estimation. The methodology builds a sample of possibilities for the future, of climate series from the historical record, which is weighted to agree with selected forecasts of meteorlogy probabilities. The nonparametric method concentrates on isolated event probabilities rather than on the entire probability distribution for various variables. It sometimes assigns the same weight to all climate series in selected categories, resulting in the same relative frequency for those climate series. By changing to a parametric approach, one determines entire probability distributions that match available forecast meteorology probabilities. This allows a continuous distribution of probability across a variable, not always possible with the nonparametric approach. This paper illustrates both the nonparametric and the parametric methods with an example, comments on both approaches, and evaluates both in a selected comparison.
CROLEY, T. E. II. Great Lakes climate change hydrologic impact assessment: IJC Lake Ontario-St. Lawrence River Regulation Study. NOAA Technical Memorandum GLERL-126. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 77 pp. (2003).
Climatic change will impact on many aspects of the hydrological cycle with consequences for mankind that are interrelated and often difficult to discern. Climate warming will have impacts on Great Lakes water supply components and basin storages of water and heat that must be understood before lake level impacts can be assessed. Because the Laurentian Great Lakes possess tremendous water and heat storage capacities, they respond slowly to changed meteorological inputs. This memory damps short-term meteorological fluctuations, but allows response to longer-period fluctuations characteristic of climate change. Thus the large Great Lakes system is ideal for studying regional effects of climate changes. This project estimates hydrological impacts of changed climates over the Great Lakes from the latest general circulation model (GCM) results for the International Joint Commission’s five-year study of Lake Ontario-St. Lawrence regulation. This report concerns the US study of climate change performed by The Great Lakes Environmental Research Laboratory (GLERL). They extracted GCM output changes between a baseline period of 1961-1990 and a future 30-year period (2040-2069). GLERL adjusted historical meteorology data for the Great Lakes basin with the GCM climate changes. GLERL used a base climate (observed data) time series over 1950-1999 to define the reference of 1960-1990 suggested by the Intergovernmental Panel on Climate Change. GLERL simulated Great Lakes hydrology to estimate net water supply scenarios for each lake under each climate scenario. This report provides background on earlier Great Lakes climate change impact studies, describes the Great Lakes and their climate, presents hydrological models used in assessing climate change, and summarizes results. Detailed time series of net basin supplies to all of the Great Lakes are available for an unchanged climate scenario and four GCM-generated changed-climate scenarios. The higher air temperatures under the changed-climate scenarios lead to higher over-land evapotranspiration and lower runoff to the lakes with earlier runoff peaks since snow pack is reduced and the snow season is greatly reduced. This also results in a reduction in available soil moisture. Water temperatures increase and peak earlier; heat resident in the deep lakes increases throughout the year. Mixing of the water column diminishes, as most of the lakes become mostly monomictic, and lake evaporation increases. Ice formation is greatly reduced over winter on the deep Great Lakes, and lake evaporation increases; average net supplies drop most where precipitation increases are modest.
CROLEY, T. E. II. Weighted parametric operational hydrology forecasting. Proceedings, World Water and Environmental Resources Congress 2003, Philadelphia, PA, June 23-26, 2003. Environmental Water Resources Institute, American Society of Civil Engineers, 10 pp. (2003).
An existing non-parametric method for using meteorology probability forecasts in operational hydrology builds a sample of possibilities for the future, of climate series from the historical record, which is weighted to agree with selected forecasts of meteorology probabilities. It concentrates on isolated event probabilities rather than on the entire probability distribution of various variables. It sometimes assigns the same weight to all climate series in selected categories, resulting in the same relative frequency for those climate series. This results in a discontinuity in the probability distribution at interval boundaries. By changing to a parametric approach, one determines entire probability distributions that match available forecast meteorology probabilities. This allows a continuous distribution of probability across a variable, allowing more meaningful interpretations for all values of the variable, such as avoiding too much probability in the tails. However, a parametric method is difficult to apply when multiple variables are considered because the assumption of a distribution(s) further constrains the matching of probabilistic meteorology forecasts. The existing non-parametric method provides useful elimination of conflicting probability constraints until a feasible solution exists. The non-parametric method can be extended into a new weighted parametric hydrological forecasting technique to allow the specification of probability distributions for the meteorological variables of interest. Extended forecast comparisons reveal that the old non-parametric method utilizes more meteorological forecast information in a hydrological forecast then the new parametric method, but the new may be doing a more reasonable job in that the derived distributions are more intuitive.
CROLEY, T. E. II. and C. L. Luukkonen. Potential effects of climate change on ground water in Lansing, Michigan. Journal of the American Water Resources Association 39(1):149-163 (2003).
Computer simulations involving general circulation models, a hydrologic modeling system, and a ground water flow model indicate potential impacts of selected climate change projections on ground water levels in the Lansing, Michigan, area. General circulation models developed by the Canadian Climate Centre and the Hadley Centre generated meteorology estimates for 1961 through 1990 (as a reference condition) and for the 20 years centered on 2030 (as a changed climate condition). Using these meteorology estimates, the Great Lakes Environmental Research Laboratory's hydrologic modeling system produced corresponding period streamfiow simulations. Ground water recharge was estimated from the streamfiow simulations and from variables derived from the general circulation models. The U.S. Geological Survey developed a numerical ground water flow model of the Saginaw and glacial aquifers in the Tri-County region surrounding Lansing, Michigan. Model simulations, using the ground water recharge estimates, indicate changes in ground water levels. Within the Lansing area, simulated ground water levels in the Saginaw aquifer declined under the Canadian predictions and increased under the Hadley.
FAHNENSTIEL, G. L., C. Beckmann, S. E. Lohrenz, D. F. MILLIE, O. M. E. SCHOFIELD and M. J. McCORMICK. Standard Niskin and Van Dorn bottles inhibit phytoplankton photosynthesis in Lake Michigan. Verh. Internat. Verein. Limnol. 28:376-380 (2002).
The routine collection of water for primary production experiments may result in contamination 0f the water sample through the introduction of metals or other contaminants (FITZWATER et al. 1982, CHAVEZ & BARBER 1987, WILLIAMS & ROBERTSON 1989). These problems were first discovered in the early 1980s, and focused on the possibility of metal contamination (FITZWATER et al. 1982). Other investigators noted reduced photosynthetic rates when water was collected with standard Niskin bottles (CHAVEZ & BARBER 1987, WILLIAMS & ROBERTSON 1989), and suggested that the problem may not be metal contamination. WILLIAMS & ROBERTSON (1989) suggested that the central rubber cord of the Niskin bottle was the source of contamination. Since these studies, it has been customary for many scientists to use modified Niskin (all rubber parts replaced with silicone or Tefloncoated parts) or GoFlo bottles for collecting water in primary production studies. While these precautions are common in oceanic research, many limnologists continue to collect water samples for primary production experiments with standard Niskin (e.g. SMITH et al. 1998, MARWOOD et al. 2000) or Van Dorn bottles (e.g. LAMPMAN & MAKAREWICZ 1999, CARIGNAN et al. 2000). A relatively recent text on limnological methods suggests that Van Dorn bottles are well suited for collecting water for primary productivity experiments (WETZEL & LIKENS 1991). The purpose of this study was to compare standard or conventional techniques of water collection with so called 'clean' techniques that involve the use of GoFlo or modified Niskin bottles in a freshwater environment.
HAWLEY, N. Observations of the intermediate and benthic nepheloid layers in southern Lake Michigan during the summer of 1995. NOAA Technical Memorandum GLERL-124. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 30 pp. (2003).
During the summer of 1995 time series measurements of water transparency, water temperature, and current velocity were made at stations located in 28, 58, and 100 m of water in southern Lake Michigan. Inertial internal waves were the dominant feature of the lake circulation. These waves caused variations in the thickness and in the vertical distribution of suspended sediment in the benthic nepheloid layer. An intermediate nepheloid layer located at the base of the thermocline was also affected by the inertial waves. This layer moves up and down in response to movement of the thermocline due to both inertial waves and to upwelling and downwelling events. Although a direct link between inertial wave action and changes in the benthic nepheloid layer could not be established, the data strongly suggest that the layer is maintained by local resuspension due to a combination of inertial wave action and longer-term processes.
HAWLEY, N. and R. W. MUZZI. Observations of nepheloid layers made with an autonomous vertical profiler. Journal of Great Lakes Research 29(1):124-133 (2003).
An autonomous vertical profiler was deployed at a site in 55 m of water in southern Lake Michigan during the late summer of 2001. Profiles of temperature and water transparency were made hourly between I and 40 meters above the bottom for about 23 days (568 profiles). The temperature observations show that the depth of the thermocline changed in response to both near-inertial internal waves and to upwelling and downwelling events. The transparency measurements show the presence of both an intermediate nepheloid layer located near the base of the thermocline and a benthic nepheloid layer at the bottom. The layers were usually separated by a region of clearer water, but during one upwelling event they merged together. Changes in both the intermediate nepheloid layer and the benthic nepheloid layer occurred in response to changes in the thermocline depth. The total amount of material suspended in both the bottom 40 m and in the benthic nepheloid layer varied by over 50%. The source of the additional material appears to be local resuspension events caused either directly or indirectly by near-inertial internal waves.

Hook, T. O., E. S. Rutherford, S. J. Brines, D. M. MASON, D. J. SCHWAB, M. J. McCORMICK, G. W. Fleischer and T. J. DeSorcie. Spatially explicit measures of production of young alewives in Lake Michigan: linkage between essential fish habitat and recruitment. Estuaries 26(1):21-29 (2003).

The identification and protection of essential habitats for early life stages of fishes are necessary to sustain fish stocks. Essential fish habitat for early life stages may be defined as areas where fish densities, growth, survival, or production rates are relatively high. To identify critical habitats for young-of-year (YOY) alewives (Alosa pseudoharengus) in Lake Michigan, we integrated bioenergetics models with GIS (Geographic Information Systems) to generate spatially explicit estimates of potential population production (an index of habitat quality). These estimates were based upon YOY alewife bioenergetic growth rate potential and their salinonine predators' consumptive demand. We compared estimates of potential population production to YOY alewife yield (an index of habitat importance). Our analysis suggested that during 1994-1995, YOY alewife habitat quality and yield varied widely throughout Lake Michigan. Spatial patterns of alewife yield were not significantly correlated to habitat quality. Various mechanisms (e.g., predator migrations, lake circulation patterns, alternative strategies) may preclude YOY alewives from concentrating in areas of high habitat quality in Lake Michigan.
Hwang, H., S. W. Fisher, K. Kim, P. F. LANDRUM, R. J. Larson and D. J. Versteeg. Assessing the toxicity of dodecylbenzene sulfonate to the midge Chironomus riparius using body residues as the dose metric. Environmental Toxicology and Chemistry 22(2):302-312 (2003).
Dodecylbenzene sulfonate (DBS) is a component of linear alkylbenzene sulfonate (LAS), an anionic surfactant, mainly used in household detergents. Due to the large quantity of DBS in use, there is concern over adverse environmental effects. This work examined the toxicokinetics and toxicity of the 2-phenyl isomer of dodecylbenzene sulfonate in 4-d, lO-d, and partial life-cycle tests on the midge, Cltironamus riparius, exposed to aqueous solutions. Toxicokinetics were determined in l0-d uptake and 5-d elimination tests. The toxicokinetics were based on parent compound concentration in water and yielded an uptake coefficient (k0) of 17.5 (14.87-20.20) ml/g/h, an elimination rate constant (k,) of 0.073 (0.062-0.085) per h, a bioconcentration factor (BCF) of 56 to 240, and a half-life (11,2) of 9.5 (8.0-11.0) h. Biotransformation measurements did not reveal evidence for DBS metabolism. Thus, body residues, determined in the toxicity study, represent parent compound. In toxicity tests. 4- and lO-d LR5Os (the body residue required to cause 50% mortality) in live midges were 0.72 (0.65-0.79) and 0.18 (0.08-0.42) mmol/kg, respectively. Thirty-day LR5Os were 0.18 (0.09-1.64) and 0.21(0.15-0.39) mmol/kg in duplicate studies. Of the sublethal endpoints, only developmental time increase was significant, with the lowest-observed-effect residues of 0.085 (0.067-0.105) and 0.100 (0.087-0.114) mmol/kg for male and female midges, respectively. Deformities in surviving larvae were also observed as chronic responses for body residues exceeding the 30-d LR5O. The body residues required for mortality suggest that DBS acts like a polar narcotic in the midge.
Ingersoll, C. G., E. L. Brunson, N. Wang, F. J. Dwyer, G. T. Ankley, D. R. Mount, J. Huckins, J. Petty and P. F. LANDRUM. Uptake and depuration of nonionic organic contaminants from sediment by the oligochaete, Lumbriculus variegatus. Environmental Toxicology and Chemistry 22(3):872-885 (2003).
Uptake of sediment-associated contaminants by the oligochaete Lumbriculus variegatus was evaluated after 1, 3, 7, 14, 28, and 56 d of exposure to a field-collected sediment contaminated with DDT and its metabolites, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE), or to a field-collected sediment contaminated with polycyclic aromatic hydrocarbons (PAHs). Depuration of contaminants by oligochaetes in a control sediment or in water was also evaluated over a 7-d period after 28 d of exposure to the field-collected sediments. Accumulation of PAHs with a log octanol-water partitioning coefficient (log K,j <5.6 typically reached a peak at day 3, followed by a lower plateau between days 7 and 56 of the sediment exposure. Similarly, 4,4'-DDT exhibited a peak in accumulation at day 14 followed by a decline at days 28 and 56. In contrast, accumulation
Kerfoot, W. C., S. L. Harting, R. Rossmann and J. A. ROBBINS. Elemental mercury in copper, silver, and gold ores: an unexpected contribution to Lake Superior sediments with global implications. Geochemistry: Exploration, Environment, Analysis 2:185-202 (2003).
Mercury and copper inventories are low in central Lake Superior and increase markedly towards the Keweenaw Peninsula. Total copper flux to Lake Superior sediments averages 5.0 + 2.5 ug cm 2 year (mean + 95% confidence limits), whereas mercury flux averages 7.5 ± 4.2 ng cm-2 year-1. In the Keweenaw Peninsula region, copper, mercury and silver inventories are elevated and highly correlated. High copper, silver and mercury inventories can be traced back to shoreline stamp sand piles, the parent ores and to smelters. Mercury occurs in elemental form, probably as a natural amalgam, in native metal (copper, silver, gold) deposits and was liberated as volatile Hg° during on-site copper smelting. Stamp mills discharged at least 364 Mt of 'stamp sand' tailings, whereas smelters refined 5 Mt of native copper, liberating together at least 42 t of mercury. The Keweenaw situation is not unique, as mineral-bound mercury is commonplace in US and Canadian Greenstone Belts and is of worldwide occurrence in massive base metal ores.
LANDRUM, P. F., G. R. Lotufo, D. C. GOSSIAUX, M. L. GEDEON and J.-H. Lee. Bioaccumulation and critical body residue of PAHs in the amphipod, Diporeia spp.: Additional evidence to support toxicity additivity for PAH mixtures. Chemosphere 51:481-489 (2003).
Polycyclic aromatic hydrocarbons (PAHs) are considered to act additively when exposed as congener mixtures. Additive internal concentrations at the site of toxic action is the basis for recent efforts to establish a sum PAH guideline for sediment-associated PAH toxicity. This study determined the toxicity of several PAH congeners on a body residue basis in Diporeia spp. These values were compared to the previously established LR50 value for a PAH mixture based on the molar sum of PAH congeners and demonstrated similar LR50 values for individual PAH. These results support the contention that the PAH act at the same molar concentration whether present as individual compounds or in mixture. Aqueous exposures were conducted for 28 d, and the water was exchanged daily to maintain the exposure concentration. The concentration in the exposures declined by an average of 22% between water exchanges across all compounds, and ranged from 11% to 32%. The toxicokinetics were determined using both time-weighted-average (TWA) and time-variable water concentrations and were not statistically different between the two source functions. Toxicity was determined for both mortality and immobility (failure to swim on prodding) and on both a TWA water concentration and a body residue basis. The LC50 values ranged from 1757 ug L-1 for naphthalene after 10 d exposure to 79.1 ug L-1 for pyrene after 28 d exposure, and the EC50 ranged from 1587 ug L-1 for naphthalene after 10 d exposure to 38.2 ug L-1 for pyrene after 28 d exposure. The LR50 values for all congeners at all lengths of exposure were essentially constant and averaged 7:5 - 2:6 umol g-1, while the ER50 for immobility averaged 2:6 - 0:6 lumol g-1. The bioconcentration factor declined with increasing exposure concentration and was driven primarily by a lower uptake rate with increasing dose, while the elimination remained essentially constant for each compound.
LANDRUM, P. F., L. L. SANO, M. A. MAPILI, E. GARCIA, A. M. KRUEGER and R. A. Moll. Degradation of chemical biocides with application to ballast water treatment. NOAA Technical Memorandum GLERL-123. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 37 pp. (2003).
Biocide treatment of ballast tanks has been proposed as one possible method for reducing the number of nonindigenous species released into the Laurentian Great Lakes. One of the more widely cited drawbacks of biocide use is the potential for environmental effects to native organisms when the biocide is released into receiving waters. This report describes results from studies evaluating the degradation rates of three different biocides that could be used for treating the ballast water of transoceanic NOBOB (no ballast on board) vessels that trade on the Great Lakes. The three biocides tested were glutaraldehyde, Disinfekt 1000® (a glutaraldehyde-surfactant adjuvant mixture), and sodium hypochlorite (NaOCl). The data were collected as part of a larger study examining the efficacy of utilizing these biocides for ballast water treatment.
LANG, G. A. and D. J. SCHWAB. Episodic Events: Great Lakes Experiment Data Archive. NOAA, Great Lakes Environmental Research Laboratory, Ann Arbor, MI, 2 CD-ROM Set pp. (2003).
The Episodic Events - Great Lakes Experiment (EEGLE) combined an integrated observational program and a numerical modeling effort to identify, quantify, and develop prediction tools for the winter-spring coastal sediment resuspension event in Lake Michigan and to assess the impact of this event on the transport and transformation of biogeochemically important materials (BIMS) and on lake ecology. The program, which lasted 5 years, was jointly funded by NOAA Coastal Ocean Program and NSF Division of Ocean Sciences. The program was developed in response to the NOAA Coastal Ocean Program and NSF Division of Ocean Sciences Joint Announcement of Opportunity for Coastal Studies in the Great Lakes (NSF Publication 97-38). The first three years (1998-2000) were devoted to fieldwork, with the final two years (2001-2002) dedicated to modeling and synthesis. All data on this 2 CD-ROM set are in HTML or ASCII flat files. A small number of files are also available in EXCEL format. A standard web browser is recommended to navigate within the data set.
LESHKEVICH, G. A. and S. LIU. Environmental monitoring of the Great Lakes using CoastWatch data and JAVA GIS. Backscatter Magazine Spring 2003:13-16 (2003).
Many of the issues and problems that coastal and ecosystem managers address don't stop at the land's edge. Just as the land side of the coastal zone can affect nearshore and offshore areas, lake-wide or localized events can impact near shore and shore areas. Examples include erosion caused by wind driven waves, ice damage to shore structures, toxic blooms that can close beaches, nutrient and sediment laden plumes that can redistribute toxic materials, and exotic species, such as the zebra mussel, tha can change the ecosytem and cause great socio-economic loss. As coastal and lake management becomes a higher priority for state coastal programs and regulatory agencies, geospatial technology, such as geographic information systems (GIS), the Global Positioning System (GPS), remote sensing information (especially from satellite), and the internet, will provide more and more data and tools that can aid in timely, integrated analysis and decision making for coastal and basin-wide management.
LOFGREN, B. M. Coupled atmospheric-land-lake climate simulation using a regional model. Verh. Internat. Verin. Limnol. 28:1745-1748 (2002).
The use of general circulation models (GCM) is standard practice for simulating the effects of an increase in atmospheric greenhouse gases or other climate forcings at the global scale. Their coarse resolution, usually dividing the globe into cells with an extent of at least 2° of latitude or longitude on a side, renders them of limited use when considering the influence of inland water bodies of much smaller scale, or when directly simulating the effects on the temperature profiles and evaporation rates of those water bodies. One way to improve the spatial resolution of climate models is to nest a regional model within a GCM. This method has been applied for short periods of time (10 days) specifically ovd the Laurentian Great Lakes (BATES et al. 1993) and for longer periods over different portions of the world (e.g. DAt et al. 1999, LIsT0N & PIELKE 2000). A long-term regional climate model simulation keying on the sensitivity of the surface-atmosphere energy and moisture exchange to the areal extent of the Aral Sea by SMALL et al. (2001) was most similar to the work of the present study. The results of the present study come from simulations of the climate of the Lauren-tan Great Lakes Basin in scenarios with different greenhouse gas concentrations. Because the future scenario, centered about the year 2030, has been run for a period of only 1.5 years, the results presented here should be regarded as preliminary.
LOFGREN, B. M. Simulation of possible future effects of Greenhouse Warming on Great Lakes water supply using a regional climate model. Proceedings, 17th Conference on Hydrology, Long Beach, CA, February 8-13, 2003. American Meteorological Society, Boston, MA, 4 pp. (2003).
The Laurentian Great Lakes contain about 20% of the world’s surface freshwater and cover a total area of 247,000 km2. The land portion of their drainage basin covers 534,000 km2. Because of their large surface area, the lakes exert a strong influence on the climate of neighboring regions. They also represent a major resource for various water uses, including consumptive use, ecological habitats, shipping, hydroelectric, and recreational
LOFGREN, B. M., F. H. QUINN, A. H. CLITES, R. A. ASSEL, A. J. Eberhardt and C. L. Luukkonen. Evaluation of potential impacts on Great lakes water resources based on climate scenarios of two GCMs. Journal of Great Lakes Research 28(4):537-554 (2002).
The results of general circulation model predictions of the effects of climate change from the Canadian Centre for Climate Modeling and Analysis (model CGCM1) and the United Kingdom Meteorological Office's Hadley Centre (model HadCM2) have been used to derive potential impacts on the water resources of the Great Lakes basin. These impacts can influence the levels of the Great Lakes and the volumes of channel flow among them, thus affecting their value for interests such as riparians, shippers, recreational boaters, and natural ecosystems. On one hand, a hydrological modeling suite using input data from the CGCM1 predicts large drops in lake levels, up to a maximum of 1.38 m on Lakes Michigan and Huron by 2090. This is due to a combination of a decrease in precipitation and an increase in air temperature that leads to an increase in evaporation. On the other hand, using input from HadCM2, rises in lake levels are predicted, up to a maximum of 0.35 m on Lakes Michigan and Huron by 2090, due to increased precipitation and a reduced increase in air temperature. An interest satisfaction model shows sharp decreases in the satisfaction of the interests of commercial navigation, recreational boating, riparians, and hydropower due to lake level decreases. Most interest satisfaction scores are also reduced by lake level increases. Drastic reductions in ice cover also result from the temperature increases such that under the CGCM1 predictions, most of Lake Erie has 96% of its winters ice-free by 2090. Assessment is also made of impacts on the groundwater-dependent region of Lansing, Michigan.
LOZANO, S. J., M. L. GEDEON and P. F. LANDRUM. The effects of temperature and organism size on the feeding rate and modeled chemical accumulation in Diporeia spp. for Lake Michigan sediments. Journal of Great Lakes Research 29(1):79-88 (2003).
Diporeia spp. are one of the most important benthic organisms in the Great Lakes. These amphipods represent a major prey item for most fish at some stage in the fish life cycle. Understanding of the physiology, energetics, and exposure to sediment-associated contaminants of Diporeia requires studies of their feeding behavior. This work examined the role of temperature and organism size on the feeding rate, measured as fecal pellet output, for lake sediments. The feeding rate was measured at 2, 4, 8, and 12°C after 3- and 7-d exposure in sieved Lake Michigan sediment. Amphipod feeding rates declined exponentially with increasing mass and increased exponentially with temperature. The relationship between feeding rate, temperature (C), and size (mg) is described by the following equation: FRt,s = 10-1.22(±0.08) . T0.83(±0.09) . W-0.84(± 0.08), r2=0.63 where FR =feeding rate, T = temperature CC), W = size (mg), and standard errors in parentheses. The relationship between feeding rate, temperature, and size allowed for improved parameterization of a contaminants uptake model for Diporeia. Model results show that the concentration of a contaminant in Diporeia biomass was lowest in April at 100 m and highest in June at 15 m and 45 m. The concentration was 2.3 and 2.9 times greater at 15 m and 45 m compared to the concentration at 100 m.
MERKEY, D. H. Restoration monitoring of freshwater coastal habitats. Proceedings of the 13th Biennial Coastal Zone Conference, Baltimore, MD, July 13-17, 2003. NOAA Coastal Services Center, Charleston, SC, 6 pp. pp. (2003).
The Estuary Restoration Act of 2000 calls for the restoration of 1 million acres of estuarine habitats by 2010 (ERA 2000). Included in the ERA's jurisdiction are all coastal areas that have "unimpaired connections with the open sea and where the seawater is measurably diluted with fresh water derived from land drainage". Also included under the definition of estuaries are near coastal waters and wetlands of the Great Lakes similar in form and function to estuaries (i.e. wetlands and riparian areas associated with drown river mouths) (ERA 2000). The inland boundary where saltwater and freshwater mixes, changes over time depending on the relative amount of freshwater drainage and recent storm activity. Therefore, the inland limit of estuaries has been extended to the head of tide in marine coastal systems (Federal Register 2002).
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 diel 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 persisted throughout the summer. This layer, constrained between the 6°C and 10°C isotherms, generally followed the internal thermocline fluctuations. These backscatter data demonstrate that determining characteristics of diel migration, and monitoring zooplankton temporal and spatial variability are possible using ADCPs.
MILLER, G. S., M. J. McCORMICK, J. H. SAYLOR, R. C. Murthy and Y. R. Rao. Temporal and spatial variability of the resuspension coastal plume in southern Lake Michigan inferred from ADCP backscatter. Verh. Internat. Verein. Limnol. 28:513-518 (2002).
In August 1997, the National Oceanic and Atmospheric Administration (NOAA) -Coastal Ocean Program (COP) and National Science Foundation Coastal Ocean Process (CoOP) funded a 5-year program to study 'the impact of episodic events on the nearshore-offshore transport and evolution of bio-geochemically important materials in the Great Lakes'. This program, Episodic Events: Great Lakes Experiment (EEGLE), being coordinated by the NOAAs Great Lakes Environmental Research Laboratory (GLERL) in Ann Arbor, Michigan, is a 5-year study involving 17 government and academic research institutions and over 40 scientists. A 10-km wide plume of suspended material extending over 300 km along the southern shores of Lake Michigan was first observed in satellite imagery (MORTIMER 1988). Satellite observations during the last decade have shown annually recurrent plumes in southern Lake Michigan initiated by major winter-spring storms. Unfortunately, AVHRR satellite images suitable for observing the plume are visual images captured only during cloudless days, an infrequent occurrence during winter over the Great Lakes. The maximum plume events for the last 3 years, as determined from satellite images, are shown in Fig. 1. The plume often veers offshore along the eastern shore, which also coincides with the region of maximum long-term sediment accumulation in the lake (LINEBACK & GROSS 1972, EDGINGTON & ROBBINS1990, EADIE et al. 1996). Preliminary estimates suggest that the particulate matter in the plume is in the range of 4 MMT, greater than the total annual load of fine sediments into Lake Michigan. These resus- pension events also resuspend and transport large quantities of nutrients and contaminants. Therefore, southern Lake Michigan is an ideal location for studying internal recycling of biogeochemically important materials, ecosystem responses, and the cross-shore transport of these materials in the Great Lakes.
Mora, C., P. M. Chittaro, P. F. Sale, J. P. Kritzer and S. A. LUDSIN. Patterns and processes in reef fish diversity. Nature 421:933-936 (2003).
A central aim of ecology is to explain the heterogeneous distribution on biodiversity on earth. As expectations of diversity loss grow, this understanding is also critical for effective management and conservation. Although explanations for bio-diversity patterns are still a matter for intense debate, they have often been considered to be scale-dependent. At large geographical scales, biogeographers have suggested that variation in species richness results from factors such as area, temperature, environmental stability, and geological processes, among many others. From the species pools generated by these large-scale processes, commmunity ecologists have suggested that local-scale assembly of communities is achieved through processes such as competition, predation, recruitment, disturbances, and immigration. Here we analyze hypotheses on speciation and dispersal for reef fish from the Indian and Pacific Oceans and show how dispersal from a major centre of origination can simultaneously account for both large-scale gradients in species richness and the structure of local communities.
Murthy, C. R., Y. R. Rao, M. J. McCORMICK, G. S. MILLER and J. H. SAYLOR. Coastal exchange characteristics during unstratified season in southern Lake Michigan. Verh. Internat. Verein. Limnol. 28:299-302 (2002).
In the Great Lakes, as well as in the coastal oceans, the gradients of many biogeochemically important materials (BIMs) are considerably higher in the off-shore direction than in the alongshore direction (BRINK et al. 1992). In the presence of these large gradients, cross-isobath circulation is a primary mechanism for the exchange of material between nearshore and offshore waters. In the coastal regions of the Great Lakes it has been observed that the mean alongshore transport is much larger than the cross-shore transport. However, both the alongshore and cross-shore current components exhibit strong episodic behavior due to wind forcing. In order to understand the cross-shore transport of BIMs, and to quantify the physical processes that are responsible for the nearshore-offshore mass exchange, a multidisciplinary research program, EEGLE (Episodic Events Great Lakes Experiment) was recently initiated by NOAA (National Oceanic and Atmospheric Administration) and NSF (National Science Foundation) in Lake Michigan.
Murthy, R. C., R. Y. Rao and M. J. McCORMICK. Circulation in southern Lake Michigan during winter season and during northerly storm episodes. Proceedings of the Fourth International Lake Ladoga Symposium 2003, University of Joensuu, Joensuu, Finland, Publications of Karelian Institute, 138:84-89 pp. (2003).
Satellite imagery from early 1996 captured the initiation, development, and decay of a recurrent coastal plume in southern Lake Michigan (Eadie et al. 1996). A 10 km wide plume of resuspended material extending over 100 km along the southern shore of Lake Michigan coincided with the disappearance of the ice in the southern basin in late March, and with occurrence of a major storm with strong northerly winds. Circulation in the lakes is driven by wind, but the effects of earth's rotation, basin topography, and vertical density structure are also important. During the unstratified season, the higher wind speeds and the absence of the thermocline allow the effects of wind action to penetrate deeper into the water column. In shallow water the entire water mass moves in the direction of the wind, while return flow occurs in the deeper parts of the lake with a relatively uniform over-lake wind field. This forms two counter-rotating closed gyres, a cyclonic gyre to the right of the wind and an anticyclonic gyre to the left (Saylor et al. 1980). These rotary motions or vorticity waves have been suggested as one of the important mechanisms for nearshoreoffshore transport in the Great Lakes. In order to understand the cross-shore transport of material and quantify the physical processes that are responsible for the nearshore-offshore mass exchange, a multidisciplinary research program, EEGLE (Episodic Events Great Lakes Experiment) was initiated in Lake Michigan by US National Science Foundation (NSF) and National Oceanic and Atmospheric Administration (NOAA).
NALEPA, T. F., D. L. FANSLOW, M. B. LANSING and G. A. LANG. Trends in the benthic macroinvertebrate community of Saginaw Bay, 1987-96: Responses to phosphorus abatement and Dreissena polymorpha. Journal of Great Lakes Research 29(1):14-33 (2003).
Trends in benthic macroinvertebrate populations were examined in inner and outer Saginaw Bay, Lake Huron, from 1987 to 1996. These years represent the time period after phosphorus abatement, but immediately before (1987 to 1990) and after (1991 to 1996) colonization of the bay by the zebra mussel, Dreissena polymorpha. In 1987 to 1990, densities of the major macroinvertebrate groups in the inner and outer bay were not significantly different from, or were greater than, densities reported just
Nghiem, S. V. and G. A. LESHKEVICH. Great Lakes ice mapping with satellite scatterometer data. Final Technical Report, JPL Task Plan 70-6362, JPL Task Order 15407. NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 26 pp. (2003).
We develop algorithms for Great Lakes ice cover mapping with satellite scatterometer data acquired by NASA satellite Ku-band scatterometers. The wide-swath scatterometers provide a large spatial coverage with high temporal resolution data to map Great Lakes ice cover for applications to marine resource management, lake fisheries and ecosystem studies, and Great Lakes climatology. This project can provide important ice cover information derived from scatterometer data to the NOAA Great Lakes CoastWatch node for public distribution via the Internet through the Great Lakes CoastWatch web site. The approach is to use in-situ and ground truth measurements from our 1997 Great LAkes Winter EXperiments (GLAWEX 1997) and from the Great Lakes Marine Weather Network in conjunction with concurrent satellite SAR data from ERS and RADARSAT and scatterometer data to determine scatterometer backscatter signatures of different lake ice types. The backscatter signatures are used to develop the ice-mapping algorithm using NSCAT and SeaWinds data. The verification of ice mapping results is carried out with in-situ observations from US Coast Guard (USCG) icebreaker vessels. In addition, we installed and operated a web camera on Granite Island to monitor ice cover over an area in Lake Superior to verify time-series scatterometer results. Potential users of the ice mapping results include the National Oceanic and Atmospheric Administration (NOAA) CoastWatch, National Weather Service (NWS), US National Ice Center (NIC), US Coast Guard (USCG), Canadian Ice Service (CIS), Canadian Coast Guard (CCG), and the Great Lakes Research Consortium.
Nghiem, S. V. and G. A. LESHKEVICH. Great Lakes Winter Experiment 2002 (GLAWEX 2002). Synthetic aperture radar applications to ice-covered lakes and rivers. JPL D-26226. NASA, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, 10 pp. (2003).
The Laurentian Great Lakes with its vast natural resource contribute significantly to economic and social activities of North America. This area provides 20% of the United States gross national product, 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. Information on ice concentration, the areal percentage of ice coverage on the lake surface, is valuable to the shipping industry and to all involved in winter navigation. Extending the winter navigation season can save millions of dollars in coal and ore shipping. Ice can impose navigation hazards in marine ports such as Duluth and Chicago and important waterways such as the St. Mary River and the St. Lawrence Seaway.
Nuurinen, S., P. F. LANDRUM, L. J. Schuler, J. V. K. Kukkonen and M. J. Lydy. Toxicokinetics of organic contaminants in Hyalella azteca. Archives of Environmental Contamination and Toxicology 44:467-475 (2003).
Uptake, biotransformation, and elimination rates were determined for pentachiorophenol (PCP), methyl parathion (MP), fluoranthene (FU), and 2,2' ,4,4' ,5,5 '-hexachiorobiphenyl (HCBP) using juvenile Hyalella azteca under water-only exposures. A two-compartment model that included biotransformation described the kinetics for each chemical. The uptake clearance coefficients (ku) were 25.7 ± 2.9, 11.5 ± 1.1, 184.4 ± 9.3, and 251.7 ± 9.0 (ml g' h') for PCP, MP, FU, and HCBP, respectively. The elimination rate constant of the parent compound (kep) for MP was almost an order of magnitude faster (0.403 ± 0.070 h') than for PCP and FU (0.061 ± 0.034 and 0.040 ± 0.008 h). The elimination rate constants for FU and PCP metabolites (kern) were similar to the parent compound elimination 0.040 ± 0.005 h and 0.076 ± 0.012 h , respectively. For MP, the metabolites were excreted much more slowly than the parent compound (0.021 ± 0.001 h-'). For PCP, FU, and MP whose metabolites were measured, the biological half-life (t112) of the parent compound was shorter than the half-life for metabolites (tii2m) because the rate is driven both by elimination and biotransformation processes. Thus, H. azteca is capable of metabolizing compounds with varying chemical structures and modes of toxic action, which may complicate interpretation of toxicity and bioaccumulation results. This finding improves our understanding of H. azteca as a test organism, because most biomonitoring activities do not account for biotransformation and some metabolites can contribute significantly to the noted toxicity.
PEACOR, S. D. Phenotypic modifications to conspecific density arising from predation risk assessment. Oikos 100(2):409-415 (2003).
Organisms often perceive predation risk through visual, auditory, or chemical cues that accompany or persist after an attack on other prey individuals. In this paper an argument is developed that suggests that it is adaptive for species that use such indirect cues to include conspecific density in the assessment of predation risk, and to respond to conspecific density by modifying phenotype (e.g. behavior, morphology of life history). A model based on this argument predicts that at equivalent (including negligible) indirect cue levels an organism should adopt less vulnerable phenotypes at lower conspecific density. Further, the phenotypic modifications to differences in conspecific density are predicted to be on the same order of magnitude as phenotypic responses to differences in predator density, to be more pronounced at higher indirect cue levels, and can be extended to responses to differences in the density of heterospecific species that share predators. This ‘‘risk assessment’’ mechanism is qualitatively different from other mechanisms, such as the dilution and ‘‘many eyes’’ effects that predict behavioral responses to conspecific density. If species use conspecific or heterospecific density to assess predation risk as predicted, there may be implications for the role and evolution of traits used to perceive conspecific and heterospecific densities, species aggregation, and population dynamics, and should be considered in the design of experiments of nonlethal effects of predators.
Pfister, C. A. and S. D. PEACOR. Variable performance of individuals: the role of population density and endogenously formed landscape heterogeneity. Journal of Animal Ecology 72:725-735 (2003).
1. Individuals can show positive correlations in performance (e.g. growth and repro-duction) through time beyond the effects of size or age. This ‘performance auto-correlation’ has been attributed previously to traits that differ among individuals or to extrinsic generators of environmental heterogeneity. 2. A model of mobile consumers on a dynamic resource showed that consumer foraging gave rise to resource heterogeneity that in turn generated autocorrelation in growth in consumers. 3. Resource heterogeneity and growth autocorrelation were most pronounced when consumers were poorer foragers, moving locally and with an imperfect ability to identify the highest resource cells. 4. The model predicted that lowered population density enhanced resource hetero-geneity and the strength of growth autocorrelation. 5. Consistent with model predictions, an experiment with tidepool limpets demonstrated that autocorrelation in growth changed with population density, with individuals in lower density tidepools showing stronger temporal correlations in growth. 6. Our model and empirical results contrast with those of previous studies with plants, where dominance and suppression increases with increasing density. 7. Our results suggest that growth autocorrelation can occur without invoking size-dependent advantages, intrinsic trait differences or extrinsic generators of environmental heterogeneity.
POTHOVEN, S. A., G. L. FAHNENSTIEL and H. A. VANDERPLOEG. Population characteristics of Bythotrephes in Lake Michigan. Journal of Great Lakes Research 29(1):145-156 (2003).
The population characteristics of Bythotrephes were evaluated at seven nearshore (45 m) and eight offshore (80 to 150 m) stations in Lake Michigan during July and September 2000. Bythotrephes was generally most abundant at offshore stations, but mean density was patchy (4 to 1,326/m2) among locations. During the year, there was a shift from reproduction by mainly instar III females. The shift generally reflected a change in the population structure of Bythotrephes at most sites during the same period. Bythotrephes populations in July were generally characterized by small body size at reproduction (instar II and III), large clutch size, and small neonates. Later in the season, body size at reproduction and neonates were larger and clutch size was smaller. Most growth (body length) of Bythotrephes occurred between instar I and II whereas little growth occurred between instar II and III. Spine length of Bythotrephes increased between July and September. The population characteristics and reproductive strategies of Bythotrephes appear to be adaptations to fish predation and food limitations.
PRICE, H., S. A. POTHOVEN, M. J. McCORMICK, P. C. Jensen and G. L. FAHNENSTIEL. Temperature influence on commercial Lake Whitefish harvest in eastern Lake Michigan. Journal of Great Lakes Research 29(2):296-300 (2003).
Lake whitefish (Coregonus clupeaformis) support the largest commercial fishery in Lake Michigan, yet relatively little is known of the thermal ecology of free-ranging lake whitefish. In 2000 six commercial trap nets were instrumented with self-recording temperature data loggers to examine the relationship between lake whitefish harvest, water temperature statistics, and fishing effort. Several variables including surface water temperature (SWT), bottom water temperature (BWT), difference between SWT and BWT, and fishing effort were used in both a backward and forward stepwise regression model against fishing harvest. Both the backward and forward results generated similar R2 statistics of 0.62 and 0.58 respectively, with the backward model suggesting BWT, variance of BWT, and the difference between SWT and BWT as the best regression model. The forward regression results suggested that SWT alone was the best model. Subsequent ANOVA tests support selecting the simpler model for describing the lake whitefish dependence on temperature, which was:
RAUDSEPP, U., D. BELETSKY and D. J. SCHWAB. Basin scale topographic waves in the Gulf of Riga. Journal of Physical Oceanography 33:1129-1140 (2003).
A two-dimensional circulation model has been used to test the hypothesis of whether the observed low-frequency current variations in the central Gulf of Riga, Baltic Sea, can be explained by basin-scale topographic wave response. A comparison of two-dimensional model results with measurements from a single current meter in the gulf showed good correlation. More sophisticated three-dimensional barotropic and baroclinic models provided only marginal improvement over the two-dimensional model. The model results indicate that wind-
Rodionov, S. and R. A. ASSEL. Winter severity in the Great Lakes region: A tale of two oscillations. Climate Research 24:19-31 (2003).
The effects of Pacific Decadal Oscillation (PDO) and the El Niño-Southern Oscillation (ENSO) on Laurentian Great Lakes regional winter air temperature and, more generally, surface-air temperatures (SAT) over North America are examined. The relationship between ENSO and winter severity in the Great Lakes is highly nonlinear and depends on the strength of El Niño events. Significant positive correlation between the winter severity and ENSO indices noted in earlier works is limited to strong El Niño events and is associated with an expansion of positive temperature anomalies in NW North America inland toward the Great Lakes. Although both ENSO and PDO are positively correlated with the Pacific-North American (PNA) teleconnection index, a closer look at the large-scale atmospheric circulation associated with the 2 oscillations reveals a substantial difference. During warm PDO phases (not coincident with strong El Niño events), atmospheric circulation resembles the classical PNA pattern, with a strong Aleutian Low at the surface and amplified ridges and troughs in the mid-troposphere. During strong El Niflo events the Aleutian Low is also stronger than normal, but shifted eastward, to the Gulf of Alaska. Over North America, an upper atmospheric ridge on the west is not accompanied with a deep trough on the east as in the classical PNA pattern. As a result, outbreaks of cold Arctic air over the eastern US are rare and winters in the Great Lakes region are abnormally mild.
Werner, E. E. and S. D. PEACOR. A review of trait-mediated indirect interactions in ecological communities. Ecology 84(5):1083-1100 (2003).
In this paper we review the empirical studies documenting trait-mediated indirect interactions (TMIIs) in food webs. Basic models and empirical approaches that form the foundation of our conceptualization of species interactions generally assume that interactions are all intrinsic property of the two interacting species and therefore are governed by their respective densities. However, if a species reacts to the presence of a second species by altering its phenotype, then the trait changes in the reacting species can alter the per capita effect of the reacting species on other species and, consequently, population density or fitness of the other species. Such trait-mediated indirect interactions can reinforce or oppose density-mediated effects and have been largely overlooked by community ecologists. We first briefly develop the case for the broad mechanistic basis for TMIIs and then review the direct evidence for TMIIs in various permutations of simple three- to four-species food webs. We find strong evidence for quantitatively significant effects of TMIIs in a variety of aquatic and terrestrial systems. We further highlight those few studies that address the question of the relative magnitudes of density- and trait-mediated effects and the role of species densities in their transmission. These studies indicate that trait effects are often as strong or stronger than density effects. We conclude that ecological communities are replete with TMIIs arising from trait plasticity and that these effects are quantitatively important to community dynamics. Finally, we synthesize our results and indicate profitable directions for future research.
WILCOXEN, S. E., P. G. Meier and P. F. LANDRUM. The toxicity of fluoranthene to Hyalella azteca in sediment and water-only exposures under varying light spectra. Ecotoxicology and Environmental Safety 54:105-117 (2003).
In the US Environmental Protection Agency methods for sediment toxicity testing, the light regimen is specified as a 16:8 light dark cycle with 500-1000 lx. The potential for photoinduced toxic effects from this requirement is evaluated. Hyalella azteca were exposed to fluoranthene in both water only and sediment to examine the impact of light spectra on the toxicity of fluoranthene. The light sources included gold fluorescent light 500 nm), cool white fluorescent light, and UV-enhanced fluorescent light. Toxicity was determined as mortality after 10 days of exposure. The extent of mortality was determined both as LC50 and LR50 (median lethal body residue). In water-only exposures, the toxicity of fluoranthene was greatest under the UV-enhanced spectra, followed by fluorescent light, and least toxic under the gold light. Both the LC50 and LR50 values exhibited the same pattern. The toxicity under gold light gave an LR50 of 0.81 mmol kg (0.82-0.79, 95% CI) similar to values expected for the acute toxicity of nonpolar narcotic (anesthetic) compounds. The LR50 values under the other two light sources were substantially lower, 4 and 58 times lower for the fluorescent and UV-enhanced exposures, respectively. In sediment, toxicity was not significantly affected by the light source. Toxicity occurred only when the body residue concentration approached that of the LR50 under gold light from the water-only exposures. Thus, H. azteca were significantly protected from the light by burrowing into the sediment.
Yoo, L. J., J. A. Steevens and P. F. LANDRUM. Development of a new bioaccumulation testing approach: The use of DDE as a challenge chemical to predict contaminant bioaccumulation. EEDP Technical Notes Collection, ERDC/TN EEEDP-01-50. U.S. Army Engineer Research and Development Center, Vicksburg, MS, 11 pp. (2003).
This technical note describes the continued development of an alternative approach to bioaccumulation testing. It employs an effects-based approach to assess contaminant bioaccumulation in organisms while limiting the analytical chemistry requirements associated with traditional bioaccumulation tests.

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