Low ambient concentrations of trace metals including Zn may limit phytoplankton productivity in the North American Great Lakes. The microalgae Chlorella sp. UTCC 522 (Chlorophyta) and Cyclotella sp. UTCC 520 (Heterokontophyta), indigenous to the Great Lakes, were assayed for their Zn requirement and the ability for Co and Cd to metabolically substitute for Zn under conditions in which Zn bioavailability was limiting cell growth. Bioassays were conducted in the laboratory using chemically defined media and the metal buffer EDTA to control the free-ion concentrations of Zn² (10^−15.3–10⁻¹⁰ mol/L), Cd² (10^−15.1–10⁻¹⁰ mol/L), and Co² (10⁻¹⁴–10⁻¹⁰ mol/L). Influence of the metals on the phytoplankton was measured by the effect on specific growth rate. Both microalgae required Zn and could use Co and Cd as Zn substitutes; Cd was used less-effectively, although to a greater extent by the diatom Cyclotella than by the chlorophyte, Chlorella. The observed ability of the phytoplankton to use Cd and Co as Zn substitutes suggests that microalgae play an important role in the geochemical cycling of Zn, Cd and Co in large lakes, and the mobilization of Cd in lake ecosystems impacted by pollution.

Although widely promoted, the importance of science as the basis of natural resources policy-making has proven difficult to both implement and evaluate compared to the many other inputs to creating public policy. Our goals were to bring together a diverse group of stakeholders in Michigan and develop means to create a dialogue on the use of water science in policy-making and to address the disconnect between the science and water policy at the state and regional levels. To achieve these goals, we developed a series of workshops and facilitated discussions to encourage active, productive discussion with a group of 35 Water Resource Fellows (Fellows). The discussions examined the role of science in Michigan water policy. The Fellows were representatives from academia, local governments, state agencies, environmental groups, industry, agriculture, and business. We surveyed the Fellows about their views on the role of science and water issues in Michigan. Nearly half (45%) of the Fellows stated that not enough science is currently being used in water policy decisions. Several themes emerged from the facilitated discussions. The Fellows recommended a recursive decision-making approach to using science in policy making. The Fellows also expressed the need for science to be accessible, relevant to the policy community, and communicated to regulators and the general public on an ongoing basis. The workshop series process for encouraging discussion among stakeholders can be used in other collaborative decision-making efforts.

Recent invasion theory has hypothesized that newly established exotic species may initially be free of their native parasites, augmenting their population success. Others have hypothesized that invaders may introduce exotic parasites to native species and/or may become hosts to native parasites in their new habitats. Our study analyzed the parasites of two exotic Eurasian gobies that were detected in the Great Lakes in 1990: the round goby Apollonia melanostoma and the tubenose goby Proterorhinus semilunaris. We compared our results from the central region of their introduced ranges in Lakes Huron, St. Clair, and Erie with other studies in the Great Lakes over the past decade, as well as Eurasian native and nonindigenous habitats. Results showed that goby-specific metazoan parasites were absent in the Great Lakes, and all but one species were represented only as larvae, suggesting that adult parasites presently are poorly-adapted to the new gobies as hosts. Seven parasitic species are known to infest the tubenose goby in the Great Lakes, including our new finding of the acanthocephalan Southwellina hispida, and all are rare. We provide the first findings of four parasite species in the round goby and clarified two others, totaling 22 in the Great Lakes—with most being rare. In contrast, 72 round goby parasites occur in the Black Sea region. Trematodes are the most common parasitic group of the round goby in the Great Lakes, as in their native Black Sea range and Baltic Sea introduction. Holarctic trematode Diplostomum spathaceum larvae, which are one of two widely distributed species shared with Eurasia, were found in round goby eyes from all Great Lakes localities except Lake Huron proper. Our study and others reveal no overall increases in parasitism of the invasive gobies over the past decade after their establishment in the Great Lakes. In conclusion, the parasite “load” on the invasive gobies appears relatively low in comparison with their native habitats, lending support to the “enemy release hypothesis.”

The difference in 700 hPa height patterns was examined on a seasonal basis between years with high numbers and low numbers of cyclone passages through Lake Erie, and high and low numbers of strong wind events at Cleveland Hopkins Airport. These show that both cyclones and strong wind events often are associated with atmospheric patterns resembling the negative phase of the North Atlantic Oscillation, or the negative phase of the Arctic Oscillation. Custom teleconnection indices were derived from these maps of 700 hPa height differences, and the seasonal means of each of these indices were linearly regressed against the number of cyclones and the number of strong wind events in that season for each year. This procedure led to moderate, but statistically significant, correlation coefficients. This gives some basis for probabilistic prediction of cyclone passages and strong wind events at Lake Erie. Actual application in prediction will require skill also in predicting the geopotential heights, and predictions generalized over larger areas may have greater significance and robustness.

Although numbers of buffleheads (Bucephala albeola), common goldeneyes (Bucephala clangula) and long-tailed ducks (Clangula hyemalis) over-wintering on Lake Ontario have increased substantially over the past two decades, factors influencing habitat use and the potential for competition have not been investigated. The purpose of this study was to determine the relationship between prey availability and community structure of diving ducks during winter on northeastern Lake Ontario. Benthic and nektonic samples collected during fall, winter, and spring 2002–2004 indicated that macroinvertebrate numbers differed by location but generally did not decline throughout winter. Large accumulations of macroinvertebrates, apparently moved by wave action and currents, were documented in nearshore areas. Surveys showed that diving ducks congregated in mixed species flocks within areas of higher food abundance. Mixed species flocks were common in nearshore areas, likely because energy-dense foods (Amphipoda and Chironomidae) were abundant in the narrow zone of shallow water, close to shore. Although macroinvertebrate numbers likely affected habitat use by diving ducks, birds did not greatly reduce abundance of macroinvertebrates. It is unlikely that exploitative competition was occurring and interference competition appeared below threshold levels that would cause species to spatially segregate. Overall, our results suggest that food availability is not a limiting factor for buffleheads, common goldeneyes, or long-tailed ducks wintering on northeastern Lake Ontario.

Sediments of the St. Lawrence River at Cornwall, Ontario, Canada, are contaminated with mercury (Hg) due to industrial pollution. To better understand the risk to fish-consumers of Hg poisoning, patterns of Hg bioaccumulation in yellow perch were described at small spatial and temporal scales within a 10 km stretch of the river. Yellow perch (mathematically standardized to the average length of capture, 13.8 cm) from a contaminated upstream zone contained 2.3–3.6 times more mercury than fish from reference zones and a more contaminated zone only 2–3 km downstream. This was confirmed in two consecutive field seasons and with other fish species. Mercury concentrations in fish could not be accounted for by differences among study sites in fish length, age, condition factor, or growth rate. However, there were seasonal changes in the variance of the log(Hg)-size relationship and in fish size and total Hg concentrations. Possible reasons for the observed patterns could include differences among sites in: food web complexity, prey contamination, fish bioenergetics and competition, local sources of Hg, or fish movements into and out of the areas of contamination. This study demonstrated that Hg in sediments is not a reliable basis for estimating human or ecological risks. Fish tissue analysis provides a clearer and more direct measure of exposure of human consumers. Similarly, annual programs of regional-scale monitoring may overlook local-scale contamination and the change in risks of Hg exposure due to seasonal fish movements.

Adaptive cluster sampling (ACS) provides researchers with an alternative technique to estimate the abundance of rare or spatially clustered organisms, but its application in field investigations has been limited to relatively few studies. We used ACS to estimate parameters of a spatially autocorrelated population of larval sea lampreys, Petromyzon marinus, in Wilmot Creek, a Lake Ontario tributary. When compared with simple random sampling (SRS), ACS significantly increased catch per sample as well as the percentage of samples that contained larvae. Although ASC-generated samples are spatially biased, the use of established formulae enabled us to calculate unbiased estimators of mean larval density and variance. With ACS, variance was reduced, improving the precision around estimates of mean density, however; increased precision came at the price of greater sampling effort. When variance was adjusted for effort, ASC provided equal or greater efficiency than SRS in 33% of sampling events, with no apparent site or seasonal bias. Based on the knowledge that larval sea lampreys are spatially aggregated, we anticipated that ACS would result in higher precision for a greater proportion of sampling events. Nonetheless, we consider ACS to be a useful technique for evaluating larval sea lamprey populations and anticipate increased application for investigating other spatially over-dispersed species.

This study reports the results of a baseline study for COSEE (Centers for Ocean Sciences Education Excellence) Great Lakes' attempts to facilitate collaboration between scientists and educators. To characterize Great Lakes scientists' involvement in K-12 education and identify factors related to scientists' potential for the role of education partner, marine and aquatic scientists were recruited to complete a survey at a conference on the Great Lakes in 2006. Three research questions guided the study: 1) how are Great Lakes scientists involved in K-12 education, 2) what barriers may deter their participation in educational outreach, and 3) which factors are related to scientists' potential for the role of education partner. Through 94 survey responses, scientists reported their familiarity with terms in education, attitudes toward involvement, experiences, barriers and motivating factors in educational outreach. Regression analysis shows that four predictor variables account for a majority of the variance in explaining scientists' experience in collaboration with teachers (a combined predictive ability of 42%): familiarity with terms in education, professional training (educational competencies and collaborative cultures), and age. Results imply that professional training programs for research scientists may be needed to improve scientists' educational outreach capacity. Such information will be of particular value to programs such as COSEE Great Lakes whose focus is on facilitating scientist-educator interactions and improving scientists' educational outreach capacity for ocean and Great Lakes science literacy.

The exotic predatory cladoceran Bythotrephes longimanus was first observed in Lake Erie on 19 September, 1985. During the early summer immediately prior to its appearance, the cladoceran community in the central basin of Lake Erie was characterized by large populations of Bosmina longirostris, Eubosmina coregoni, Daphnia mendotae, and Daphnia retrocurva, with the latter three species persisting throughout August and September, along with Diaphanosoma spp. Community composition during early summer 1986 was similar to that of the previous year, but densities of all cladocerans decreased dramatically coincident with the appearance of Bythotrephes in mid-July, and remained suppressed throughout August and September. Only D. mendotae was present in appreciable numbers during this period; from mid-July through the end of August, 86–98% of cladoceran biomass (exclusive of Bythotrephes and Leptodora) was contributed by D. mendotae. Densities of Leptodora and Bythotrephes showed a strikingly inverse relationship, both temporally and spatially, during 1986. Size frequency distributions of D. mendotae exhibited an immediate shift towards extremely large (> 2.5 mm) individuals coincident with Bythotrephes' appearance in 1986, suggesting an upper size limit to efficient prey utilization by Bythotrephes. These results suggest that Bythotrephes can have substantial impacts both on cladoceran community composition, and on the size distributions of individual species.

Colonial waterbirds are an important component of Great Lakes ecosystems. In order to investigate the role these birds play in an aquatic food web, bioenergetics models, using allometric equations, were applied to breeding double-crested cormorants (Phalacrocorax auritus) and their offspring in the Beaver Archipelago, northern Lake Michigan. These models were parameterized using detailed information collected during the 2000 and 2001 breeding seasons, as well as literature values. Each breeding season was divided into stages in the models to reflect changes in cormorant diet and population size documented in the study area. The models estimated the total prey biomass consumed as 1,445 metric tonnes (mt) of prey in 2000, and 1,585 mt of prey in 2001. Each year, the majority of the prey biomass was alewife (Alosa pseudoharengus), with these fish comprising a greater percentage of prey biomass consumed in 2001. An increase in cormorant reproductive success in 2001 may be linked to this increase in alewife biomass consumed; the breeding bird population size, however, declined in 2001 as compared to 2000. The other prey items, which are not considered to be species of commercial or sport value, were also important contributors to bird diet and consumption of these species did tend to vary from year-to-year. Overall, the application of bioenergetics models allows for greater understanding of the role of cormorants as predators and as energy links in the system.

Alewife, Alosa pseudoharengus, have been recognized for several decades as one of the most important forage fish in the Laurentian Great Lakes. Although massive alewife die-offs have regularly been observed throughout the Great Lakes and other inland lakes, little substantive information is available regarding physiological mechanisms associated with adult alewife mortality. Long-term field surveys have shown a correlation between cold winter temperatures, poor condition and adult alewife mortality. In this study, adult alewife were raised in replicate pond systems and subjected to contrasting cold temperatures (4 and < 2°C) representing mild and severe winter conditions. We evaluated alewife mortality, condition and immune response to these temperatures. In contrast to our expectations, alewife exposed to mild and severe winter temperatures showed no difference in mortality or condition (measured as the ratio of dry to wet weight). Survival of alewife held in ponds with mild winter conditions (~ 4°C) was similar to that of alewife exposed to prolonged periods (more than six weeks) of temperatures < 2°C. This result contrasts with previous observations indicating that alewife cannot tolerate temperatures < 3°C. Circulating lymphocytes from alewife exposed to severe winter temperatures were significantly lower in number (~40%) compared to fish experiencing milder winter conditions, suggesting sub-lethal immunosuppression in response to the colder winter temperatures. Although colder winter temperatures did not directly induce alewife mortality, these results suggest that winter conditions that result in colder water temperatures can produce immunosuppression, thereby increasing alewife susceptibility to disease and mortality.

Fatty acids are potential trophic markers to trace feeding relationships in aquatic ecosystems primarily because lipid reserves of organisms broadly reflect dietary sources of lipids and can therefore provide information on the availability of key fatty acids in the food web. However, the use of fatty acids for such applications may be constrained by the degree to which the fatty acid composition of organisms is obscured by factors other than straightforward uptake from the diet. Thus, we studied the effect of long-term fasting, under controlled laboratory conditions, on the lipid content and fatty acid composition of field-caught Mysis relicta. Periods of 3 to 6 weeks are required to induce clear effects of fasting in M. relicta. Relative proportions of docosahexaenoic acid (DHA; 22:6n-3) and arachidonic acid (ARA; 20:4n-6) increased with decreasing lipid contents during fasting. DHA proportions in the total fatty acid composition of fasting M. relicta were significantly higher in comparison to field-caught animals. M. relicta with high proportions of DHA (> 25%) and with low lipid contents (< 14% of dry weight) can be clearly identified as fasting animals. Such thresholds will help to improve the validity of fatty acids in trophic studies.

The sediments of Lake Superior, Lake Huron, and Georgian Bay were sampled in 2001 and 2002 in order to evaluate the extent of surficial sediment contamination of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCs), polycyclic aromatic hydrocarbons (PAHs), and metals. Sediment concentrations of PCBs, OCs, PAHs, and mercury were generally low and up to 2 orders of magnitude less than in Lakes Erie and Ontario. In contrast, concentrations of metals such as arsenic, copper, and nickel were comparable to those in Lakes Erie and Ontario. These elevated Lakes Superior and Huron metal concentrations were attributed to naturally occurring metals within the bedrock, soil, and sediment of the study region. Concentrations of all contaminants were typically below the Canadian Sediment Quality Probable Effect Level (PEL) guidelines. With regard to spatial patterns, most contaminants were focused primarily in the depositional basins and atmospheric deposition was likely the major source of these chemicals to the lakes. The major exception was for metals (not including mercury) whose patterns were also influenced by natural sources as well as extensive mining activity. A comparison between surficial sediment contamination of samples collected as part of this survey and those collected in the late 1960s/early 1970s using similar methods showed that concentrations of DDT, PCB, lead, and mercury were generally similar between these two time periods. These results are not consistent with production and usage patterns that have declined substantially in the past 3 decades. We hypothesize that the lack of temporal trends is an artifact due to slow sediment accumulation rates as well as differences in analytical protocols between the two time periods.

A long-term monitoring program was initiated in 2003 to determine the ecological status of Muskegon Lake, a Great Lakes Area of Concern. This paper presents data generated from the first 3 years of the monitoring program, discusses how the data are being used to establish and justify lake restoration targets, and assesses how water quality conditions have changed over time. Between 1972 and 2005, lake-wide averages of total phosphorus and soluble reactive phosphorus from the water surface have declined from 68 to 27 μg/L and from 20 to 5 μg/L, respectively. In addition, average chlorophyll α concentrations have declined from 25 to 6 μg/L over this period, while Secchi disk depths have increased from 1.5 to 2.2 m. Wastewater diversion, and perhaps dreissenid filtering activity, is most likely responsible for these changes. However, nitrate concentrations have increased from 70 to 270 μg/L over the same time period. During 2003–2005, phytoplankton abundance and fish catch were lower in the spring compared to the summer and fall. Microcystis was the most abundant phytoplankton genus; the fish community generally was dominated by round goby (Neogobius melanostomus) in spring and summer, and sunfishes (Centrarchidae) in the fall. Dreissenid abundance was highly variable over time, but densities were low relative to Saginaw Bay. Approximately 65% of the Muskegon Lake shoreline has been hardened (i.e., physically altered). Overall, the water quality of Muskegon Lake has improved over the past 30 years, but environmental challenges still exist, including contaminated sediments, loss of natural habitat, and invasive species.

Observations and modeling results are presented to explore the response of a multi-basin, fjord-type lake to episodic wind forcing. Field observations show that abrupt cooling and warming events (magnitude greater than 5°C d-1) lasting 3–6 days in a large, salmon-bearing river (Quesnel River) are due to upwelling in its upstream lake (Quesnel Lake) during the summer, stratified season. Within the lake, vertical displacement of isotherms in the vicinity of the river mouth associated with this upwelling is shown to be forced by wind events longer than one quarter of the fundamental seiche period and of sufficient magnitude that the Wedderburn number approaches one. Upwelling occurs nearly-simultaneously throughout a smaller basin adjacent to the outflow (West Basin) that is separated from the Main Basin of Quesnel Lake by a sill and contraction. Wind-driven water fluxes across the sill are estimated using a conceptual model based on volume and heat budgets. These estimates provide an upper bound for flow across the sill and suggest that exchange flow may at times be internally hydraulically controlled, with epilimnetic velocities of up to ~25 cm/s. Computed fluxes suggest the West Basin hypolimnion has a residence time of 6–8 weeks during the summer stratified period with each upwelling episode irreversibly exchanging 25–30% of the hypolimnetic volume with the rest of the lake. Implications of such events are profound for salmon bearing rivers wherein the thermal habitat is critical to migration success.

Population structure and fecundity of freshwater mussels can be difficult to assess due to the benthic habitat and complex life cycles of these organisms. However, rapid and reliable classification of unionids can be accomplished with polymerase chain reaction if species-specific DNA primers are established. In this report we describe the sequence analysis of the ITS1 and ITS2 regions from five mussel species (Amblema plicata, Fusconia flava, Lampsilis siliquoidea, Ligumia nasuta, and Pyganodon grandis) isolated from a refuge in Lake Erie. Sequence comparison revealed strong similarities between A. plicata and F. flava and between L. siliquoidea and L.nasuta. P. grandis contained regions of additional DNA not present within the other species. Our study confirmed the placement of Ligumia nasuta within the Lampsilinae. The analysis also revealed DNA sequences within the ITS1 and ITS2 regions that are species-specific. Thus, the development of species-specific PCR primers can be utilized for analysis of adult populations and for glochidia on host fish.