Microplastic pollutants in the coastal dunes of Lake Erie and Lake Ontario

Microplastic particles, often studied as aquatic pollutants, have been recovered from coastal dunes along the shores of Lake Ontario and Lake Erie in New York and Pennsylvania. Surface and shallow sub-surface sand samples were collected from coastal dunes in 1 m² areas from 5 locations along Lake Erie: Sunset Bay, Dunkirk Harbor, Point Gratiot, and Canadaway Creek in New York and Presque Isle State Park Beach #11 in Pennsylvania. Samples were also collected from coastal dunes on Lake Ontario at Sandy Island Beach State Park, NY. Abundances, shapes, sizes, textures, and degradation of microplastics were characterized. Twenty-one of 26 samples yielded a variety of microplastics: pellets, fragments, and fibers. Larger microplastics (5.0–1.0 mm) were dominated by spheroidal and disk-shaped pellets with fewer fragments. Smaller microplastics (≤1.0 mm) were predominantly fibers and small fragments. Some microplastic particles exhibited evidence of degradation and weathering as a consequence of transport and exposure to the elements. The presence of microplastics in coastal dunes is attributable to aeolian transport from the adjacent beach.     

Lake Sturgeon Waters and Fisheries in New York State

Historic and contemporary records of lake sturgeon (Acipenser fulvescens) occurrences in new York State have been assembled in this report to assist in planning and prioritizing the areas for restoration. This has become important because information about this threatened species is not easily assembled nor easily retrieved from the few remaining fishermen. Lake sturgeon were identified in 17 waters of New York State in the Great Lakes drainage including Lakes Erie, Ontario, Champlain, and the Niagara and St. Lawrence rivers. Two other rivers in the Laurentain Great Lakes drainage had self-sustaining populations, five others historically supported spawning runs, and five other waters had historical records of use or relict populations. Lake Erie provided the largest historic fishery for lake sturgeon in New York State (1,678 tonne reported in 1885) followed by Lake Ontario (292 tonne reported in 1890). All the major waters (the first five identified above) had large harvests, and two tributaries to the St. Lawrence River, the Grasse and Oswegatchie rivers, also provided commercial harvests. The Great Lakes fisheries were reduced to abandonment by the 1940s and the remaining ones were discontinued by the 1960s. Currently, lake sturgeon are self-sustaining at very low levels in the upper Niagara, St. Lawrence, and the Grasse rivers. The fish is protected from harvest in all areas but one.     

Within-stream release-site fidelity of steelhead trout from Lake Erie hatchery stocks

Straying of salmonids in Lake Erie is not well understood despite the economic importance of these recreational fisheries, which are sustained by stocking approximately 2 million steelhead trout (Oncorhynchus mykiss) yearlings annually. The occurrence of straying in hatchery-reared salmonid populations can be influenced by stocking strategies, such as within-stream stocking location. Conneaut Creek provides a unique opportunity to evaluate the extent of release-site fidelity of adult steelhead trout from Lake Erie, because it is equally stocked by Ohio and Pennsylvania at different distances from the stream mouth. Adult steelhead trout were collected from two Conneaut Creek sites, Conneaut Ohio (2 km from Lake Erie) and Albion Pennsylvania (61 km from Lake Erie), in spring and fall of 2009. Elemental signatures of yearling otoliths measured by laser-ablation-inductively-coupled-plasma-mass-spectrometry were used to identify hatchery stocks. The state-specific hatchery stocks were identified with high confidence using discriminant analysis (Sr and Ba concentrations in nine otolith regions; Ohio 100.0%, Michigan 86.1%, New York 92.4%, and Pennsylvania 93.2% using jackknifed mean correct assignment). Adult steelhead trout (N = 174) collected in spring and fall at Conneaut Ohio included both Ohio and Pennsylvania-stocked fish, but no Ohio-stocked steelhead trout were collected at the Pennsylvania site in either season. Of the classified adult steelhead trout, 13.8% were identified as strays from other states (New York and Michigan). These results confirm strong release-site fidelity between Ohio and Pennsylvania stocked steelhead trout and provides fishery managers with sound scientific data to refine their stocking practices.     

Range Expansion of the Exotic Zooplankter Cercopagis pengoi (Ostroumov) into Western Lake Erie and Muskegon Lake

Previously reported from Lakes Ontario and Michigan, the nonindigenous zooplankter Cercopagis pengoi was found for the first time in western Lake Erie, the Detroit River, and Muskegon Lake, Michigan, during summer 2001. A native of the Ponto-Caspian region, C. pengoi is currently expanding its range in North America. Analysis of mitochondrial gene ND5 sequences confirmed that the Lake Erie haplotype is identical to that reported previously from Lakes Ontario and Michigan and the Finger Lakes, New York. These findings support the hypothesis that C. pengoi's range expansion in the Great Lakes likely resulted from inter-lake transfer of ballast water, rather than from additional introductions from European locations. Pleasure-craft traffic operating between Lake Michigan and Muskegon Lake is likely responsible for this inland transfer of Cercopagis, a trend that likely will increase due to human activities.     

The Invasive New Zealand Mud Snail (Potamopyrgus antipodarum) in Lake Erie

The New Zealand mud snail (Potamopyrgus antipodarum) is an invasive species in Europe, Japan, Australia, and North America. In the western United States it is a species of special concern where population densities in some rivers and streams are very large (∼300,000 per m²) and considerable ecological effects of its presence have been reported. Much less about the effects of this species is known in the Great Lakes, where the snail was found in Lake Ontario and the St. Lawrence River in 1991. Here we report the occurrence of the snail in Lake Erie. Two P. antipodarum were collected in 18 m deep water (sampling range 5–18 m) in Lake Erie off shore of Presque Isle State Park near Erie, Pennsylvania in the summer of 2005 and others were collected off of Sturgeon Point in Lake Erie (sampling range 5–20 m) south of Buffalo, NY and in the central basin of Lake Erie (18 m) in 2006. This finding demonstrates that this species continues to expand its range in the Great Lakes. The range expansion increases the likelihood that it may become established in rivers and streams emptying into the Great Lakes where higher densities and greater ecological damage may result.     

Reappearance of Deepwater Sculpin in Lake Ontario: Resurgence or Last Gasp of a Doomed Population?

Deepwater sculpin (Myoxocephalus thompsonii) were abundant in Lake Ontario in the 1920s and at least common into the 1940s. By the 1960s they were rare and, thereafter, some considered the population extirpated even though a synoptic survey of the lake in 1972 produced three, relatively large (148–165 mm total length, TL), and presumably old, specimens from the northern half of the lake. Deepwater sculpin were absent from annual survey catches in the 1980s and did not reappear until 1996, when three were caught in northern Lake Ontario. Isolated collections of deepwater sculpin continued during 1998–2004. Catches during 1996–2004 included five smaller individuals, 89-118 mm TL. In 2005, catches increased sharply, with 18 deepwater sculpin collected from southern waters and one from northern waters. Moreover, young, small sculpin were dominant in 2005–16 of the 19 sculpins averaged 68 ± 12 mm total length (± 1 s.d.). The young fish observed since 1996 could have originated from reproduction by the small in-lake population, from downstream drift of planktonic larvae from Lake Huron, or both. The presence of juveniles is a clear sign that conditions for survival of young deepwater sculpin are becoming more favorable, perhaps because of reduced abundance of alewife (Alosa pseudoharengus), a pelagic planktivore linked to depression of deepwater sculpin in Lake Michigan, and also low bundances of burbot (Lota lota) and lake trout (Salvelinus namaycush), benthic piscivores     

Post-dreissenid Increases in Transparency During Summer Stratification in the Offshore Waters of Lake Ontario: Is a Reduction in Whiting Events the Cause?

Since the dreissenid invasion of the lower Great Lakes, calcium concentrations in the offshore waters of Lake Ontario have decreased by approximately 4–5 mg/L. This decline has coincided with a three-fold reduction in August turbidity values and nearly a doubling of Secchi depths, presumably due to reduced summer calcite precipitation events in the lake. The reductions in calcium have followed a dramatic reduction in alkalinity in the central and eastern basins of Lake Erie, which provides most of the inflow to Lake Ontario. This reduction in alkalinity in Lake Erie corresponds to a period of rapid dreissenid growth in that lake, strongly suggesting calcium uptake by dreissenid mussels as a causative factor. The mass of calcium resident in the dreissenid population in Lake Erie, estimated from published lake-wide census data, is sufficient to account for the observed decreases in alkalinity. In addition, observed changes in alkalinity in Lake Ontario closely match those expected to result from inflows from Lake Erie, based on mass balance considerations. Considered in sum, our data strongly suggest that calcium uptake by dreissenid mussels in Lake Erie has resulted in decreases in the calcium concentration in Lake Ontario, reducing the frequency and/or intensity of whiting events in the latter lake. We believe this is the first report of an increase in transparency that can be reasonably attributed to a chemical change brought about by Dreissena. These increases in transparency may have very different consequences than those of dreissenid filtration activities. For example, rather than decreasing phytoplankton populations, the improved light climate might increase summer phytoplankton populations, particularly sub-epilimnetic ones.     

Contaminants Associated with Suspended Sediments in Lakes Erie and Ontario, 1997–2000

Sediment traps were installed at individual index stations in the western basin of Lake Erie and the Mississauga (central) basin of Lake Ontario, and refurbished seasonally during the period 1997–2000. In Lake Ontario, sediment down flux rates and corresponding contaminant down flux rates were highest in winter and increased with depth due to the influence of resuspended bottom sediments. Sediment down flux rates in western Lake Erie (22 to 160 g m⁻² d⁻¹) were far greater than in Lake Ontario (0.19–3.0 g m⁻² d⁻¹). Suspended material in western Lake Erie was characterized as predominately resuspended bottom sediments; down flux rates were roughly 5- to 10-fold higher in spring and fall, compared to summer. Suspended sediment concentrations of PCBs and other organochlorine contaminants, represented by both annual means and individual seasonal values, were higher in Lake Ontario throughout the duration of the study, compared to Lake Erie. The mean annual concentration of PCBs in suspended sediments over the period 1997–2000 was 330 ng/g in western Lake Erie and 530 ng/g in Lake Ontario. Based on a comparison with historical data from Lake Ontario, mean contaminant concentrations over the period 1997–2000 for PCBs, hexachlorobenzene, and mirex corresponded to decreases of 38%, 74%, and 40%, respectively, since the mid-1980s. Corresponding down flux rates for PCBs, hexachlorobenzene, and mirex decreased by approximately 70%, 90%, and 80%, respectively, since the 1980s.     

Blueback Herring (Alosa aestivalis) in Lake Ontario: First Record,Entry Route,and Colonization Potential

Two juvenile blueback herring (Alosa aestivalis) were caught in Lake Ontario in October 1995, the first record of this anadromous marine clupeid in the Great Lakes. Blueback herring most likely gained entry to Lake Ontario via the Erie Barge Canal, a navigation canal that links the Mohawk-Hudson rivers, which drain to the Atlantic Ocean, to Oneida Lake, which drains to Lake Ontario through the Oneida-Oswego rivers. Blueback herring ascend the Hudson River to spawn and were first reported from the upper Mohawk River in 1978. They currently spawn in several of the upper Mohawk's tributaries, including one about 430 km from the ocean but only 25 km from Oneida Lake. They were first found in Oneida Lake in 1982 and, in fall 1994, large numbers of juvenile blueback herring were found moving down the Oswego River. In the southern United States, blueback herring established self-reproducing populations in several reservoirs, and thus they have the potential to colonize Lake Ontario. If blueback herring become established in Lake Ontario, they could spread to other Great Lakes and impede recovery of depressed populations of indigenous fishes, like lake herring (Coregonus artedi) and lake trout (Salvelinus namaycush), through competition with, or predation on, their larvae.     

Origins of Rainbow Smelt in Lake Ontario

The first rainbow smelt (Osmerus mordax) to enter Lake Ontario were probably migrants from an anadromous strain introduced into New York's Finger Lakes. Since the upper Great Lakes were originally stocked with a landlocked strain from Green Lake, Maine, subsequent migration to Lake Ontario from Lake Erie makes Lake Ontario unique among the Great Lakes in probably having received introductions from two distinct populations.     

Inshore-offshore Distribution of Larval Fishes in Lake Superior off the Western Coast of the Keweenaw Peninsula,Michigan

We surveyed the larval fish community in Lake Superior off the western coast of the Keweenaw Peninsula, Michigan, as a first component in understanding how the Keweenaw Current affects larval fish distribution and survivorship. On transects at Ontonagon, Houghton, and Eagle Harbor, we collected larval fishes with a 1-m diameter plankton net towed through surface and deep (below metalimnion) waters at an inshore location (1 km from shore) and an offshore location (5–9 km from shore) during day and night in 1998 and 1999. The most abundant larvae caught were lake herring (Coregonus artedii), rainbow smelt (Osmerus mordax), burbot (Lota lota), deepwater sculpin (Myoxocephalus thompsoni), and spoonhead sculpin (Cottus ricei). Lake herring was generally most abundant at the surface during the day, while the other four species avoided the surface by day but not at night. Overall, larval fish density was greater inshore than offshore, with exceptions for particular locations and seasonal periods (1.24x for lake herring, 12.93x for rainbow smelt, 1.27x for burbot, 1.25x for deepwater sculpin, and 4.26x for spoonhead sculpin). Differences in the sizes of larvae between inshore and offshore locations, in conjunction with density patterns, suggest a seasonal inshore to offshore movement. Despite the presence of the Keweenaw Current, the overall distribution patterns of larval fishes follow those of previous studies conducted in the Great Lakes, but with lower densities.     

Trends in Total Phosphorus in Canadian Near–Shore Waters of the Laurentian Great Lakes: 1976–1999

Beginning as early as 1976 at many locations, total phosphorus concentrations (TP) were measured weekly in samples collected year-round in the intake water of 18 municipal water treatment plants in Canadian (Ontario) waters of the Laurentian Great Lakes. No consistent long-term trends were evident at two north-shore Lake Superior sampling locations, but there were significant long-term declines in TP measured at all three Lake Huron locations; however, concentrations there have remained relatively constant during the past decade. Declines in TP averaging about 1 μg/L/yr during 1976 to 1990 were prevalent at lower Great Lakes sampling locations and by the early 1990s TP had declined to 15–25 μg/L in Lake Erie and 10–20 μg/L in Lake Ontario. Declines generally levelled out in Lake Ontario after 1990, but TP increased substantially at some Lake Erie locations in the late 1990s. Recent (1996 to 1999) total phosphorus concentrations in north-shore Lake Erie locations in the range of 20 to 30 μg/L were 2 to 3 times higher than at Lake Ontario near-shore locations in the 8 to 11 μg/L range. Rates of decline of TP were generally highest for the March–April period (−1.88, −1.61, and −1.34 μg/L/yr in Lakes Ontario, Erie, and Huron, respectively for 1976 to 1990). The March–April Lake Ontario near-shore rate of TP decline was nearly twice as high as that reported previously for off-shore Lake Ontario (attributed to proximity to P loading sources and to lower net sedimentation losses of P in the near-shore environment). There were substantial declines in chlorophyll-to-TP ratios and in the slopes and Y-intercepts of chlorophyll-TP regressions for both Lake Erie and Lake Ontario following the establishment of dreissenid mussels.     

A cross-lake comparison of crustacean zooplankton communities in the Laurentian Great Lakes, 1997–2016

Spring and summer open-water crustacean zooplankton communities were examined across all five Laurentian Great Lakes from 1997 to 2016. Spring communities were dominated by calanoid (lakes Superior, Huron and Michigan) or cyclopoid (lakes Erie and Ontario) copepods. Volumetric biomass of summer communities increased along an assumed trophic gradient (Superior, Huron, Michigan, Ontario; eastern, central and western Erie), as did dominance by cyclopoids and cladocerans. Over the time series of the study, summer communities in lakes Michigan, Huron and Ontario shifted towards greater dominance by calanoids and greater similarity with Lake Superior. Trajectories of changes were different; however, reductions in cladocerans accounted for most of the change in lakes Michigan and Huron while reductions in cyclopoids and increases in Leptodiaptomus sicilis were behind the changes in Lake Ontario. Shifts in the predatory cladoceran community in Lake Ontario from Cercopagis pengoi to occasional dominance by Bythotrephes longimanus, a species much more vulnerable to planktivory, as well as the appearance of Daphnia mendotae in a daphnid community previously consisting almost exclusively of the smaller Daphnia retrocurva, suggest impacts of reduced vertebrate predation. In contrast, strong correlations between cladocerans and chlorophyll in lakes Michigan and Huron point to the possible importance of bottom-up forces in those lakes. Large interannual shifts in cladoceran community structure in the central and eastern basins of Lake Erie suggest intense but variable vertebrate predation pressure. The zooplankton communities of lakes Huron, Michigan and Ontario may be approaching a historic community structure represented by Lake Superior.     

Hydroacoustic Estimates of Abundance and Spatial Distribution of Pelagic Prey Fishes in Western Lake Superior

Lake herring (Coregonus artedi) and rainbow smelt (Osmerus mordax) are a valuable prey resource for the recovering lake trout (Salvelinus namaycush) in Lake Superior. However, prey biomass may be insufficient to support the current predator demand. In August 1997, we assessed the abundance and spatial distribution of pelagic coregonines and rainbow smelt in western Lake Superior by combining a 120 kHz split beam acoustics system with midwater trawls. Coregonines comprised the majority of the midwater trawl catches and the length distributions for trawl caught fish coincided with estimated sizes of acoustic targets. Overall mean pelagic prey fish biomass was 15.56 kg ha⁻¹ with the greatest fish biomass occurring in the Apostle Islands region (27.98 kg ha⁻¹), followed by the Duluth Minnesota region (20.22 kg ha⁻¹), and with the lowest biomass occurring in the open waters of western Lake Superior (9.46 kg ha⁻¹). Biomass estimates from hydroacoustics were typically 2–134 times greater than estimates derived from spring bottom trawl surveys. Prey fish biomass for Lake Superior is about order of magnitude less than acoustic estimates for Lakes Michigan and Ontario. Discrepancies observed between bioenergetics-based estimates of predator consumption of coregonines and earlier coregonine biomass estimates may be accounted for by our hydroacoustic estimates.     

Distribution of the Ponto-Caspian Amphipod Echinogammarus ischnus in the Great Lakes and Replacement of Native Gammarus fasciatus

The gammarid amphipod Echinogammarus ischnus was found to be widespread from the south end of Lake Huron, downstream in the St. Clair River and across Lake Erie to the Niagara River outlet into Lake Ontario. The presence of this exotic species was first reported in the Detroit River, where it now dominates; this species has been common in western Lake Erie since the summer of 1995. The species has replaced the native amphipod Gammarus fasciatus on rocky habitats in the St. Clair, Detroit, and Niagara rivers, and is the dominant amphipod on rocky shores in western Lake Erie. In one year, E. ischnus became the dominant amphipod at the Lake Ontario end of the Welland Canal, although the fecundity of E. ischnus is less than G. fasciatus. E. ischnus has not yet been reported from the north shore of Lake Ontario or the outlet into the St. Lawrence River but occurs 100 km further downstream at Prescott.     

Distribution and Abundance of Larval Ciscoes,Coregonus Artedii,and Burbot,Lota Lota,in Oneida Lake

Surveys of pelagic fish larvae were made in Oneida Lake, New York, during 1965-1975 with high-speed samplers. In early May, larval ciscoes, Coregonus artedii, occurred only above 5.5 m and were actively concentrated near the surface in shallow bays. The largest larvae were found at the shallowest sites and almost half the ciscoes were taken in one small, protected bay. By late May, the larvae had moved offshore, although they remained near the surface. The largest ciscoes were then at the deepest sites. This offshore movement was not strongly related to limnological conditions - water temperature, dissolved oxygen, and food (zooplankton) were similar throughout the upper water column of Oneida Lake at this time - but may have been related to size and water currents. Successive estimates of larval cisco populations suggested that offshore recruitment exceeded total mortality during May. Densities of larval burbot, Lota lota, were homogeneous (even at depths greater than 5.5 m) during May. In June, as with ciscoes, greater densities of burbot were found near the surface of the offshore sites. In early May, the largest burbot tended to occur at intermediate depths. Few larval ciscoes or burbot were captured in late June. Populations of larval ciscoes and burbot appear to be disproportionately great in relation to the abundance of adults and may contribute to the persistence of these cold-water species in an eutrophic environment.     

Trends in Mysis diluviana abundance in the Great Lakes, 2006–2016

With the large Diporeia declines in lakes Michigan, Huron, and Ontario, there is concern that a similar decline of Mysis diluviana related to oligotrophication and increased fish predation may occur. Mysis density and biomass were assessed from 2006 to 2016 using samples collected by the Great Lakes National Program Office's biomonitoring program in April and August in all five Great Lakes. Summer densities and biomasses were generally greater than spring values and both increased with bottom depth. There were no significant time trends during these 10–11 years in lakes Ontario, Michigan, or Huron, but there was a significant increase in Lake Superior. Density and biomass were highest in lakes Ontario and Superior, somewhat lower in Lake Michigan, and substantially lower in Lake Huron. A few Mysis were collected in eastern Lake Erie, indicating a small population in the deep basin of that lake. On average, mysids contributed 12–18% (spring-summer, Michigan), 18–14% (spring-summer, Superior), 30–13% (spring-summer, Ontario), and 3% (Huron) of the total open-water crustacean biomass. Size distributions consisted of two peaks, indicating a 2-year life cycle in all four of the deep lakes. Mysis were larger in Lake Ontario than in lakes Michigan, Superior, and Huron. Comparisons with available historic data indicated that mysid densities were higher in the 1960s–1990s (5 times higher in Huron, 2 times higher in Ontario, and around 40% higher in Michigan and Superior) than in 2006–2016.     

The Zebra Mussel Dreissena polymorpha Found in North America in 1986 and 1987

The zebra mussel Dreissena polymorpha was first detected in the western basin of Lake Erie, Ontario, Canada, on natural gas wellheads and well markers between April and November 1986. It was found again in 1987 on the north shore of Lake Erie in a water treatment plant, and in vessel fouling. The population increased in Lake Erie in 1988. Dreissena may have spread from Lake Erie to Lake St. Clair, where it was then discovered on 1 June 1988.     

Hydrology influences generalist–specialist bird-based indices of biotic integrity in Great Lakes coastal wetlands

Marsh bird habitats are influenced by water levels which may pose challenges for interpreting bird-based indices of wetland health. We determined how much fluctuating water levels and associated changes in emergent vegetation influence the Index of Marsh Bird Community Integrity (IMBCI) using data collected in Great Lakes coastal wetlands by participants in Bird Studies Canada's Great Lakes Marsh Monitoring Program. IMBCI scores for 90 wetlands in Lake Erie and 131 wetlands in Lake Ontario decreased with decreasing water levels due to decreasing number of marsh-dependent species in Lake Erie and perhaps also in Lake Ontario. The average magnitude of the decrease in scores between extremely high and low water periods for wetlands with sufficient data was 15% in Lake Erie where water dropped 0.9 m on average (n = 11 wetlands) and 18% in Lake Ontario where water dropped 0.5 m (n = 7). Scores in Lake Erie increased with increasing Typha due to increasing numbers of marsh-dependent species and decreased with increasing Phragmites due to increasing numbers of generalist species. The opposite was observed in Lake Ontario, perhaps due to denser Typha and sparser Phragmites. Scores were explained by the naturally fluctuating water levels of Lake Erie, which favored Phragmites expansion and the regulated water levels of Lake Ontario which promoted Typha expansion. Scores were influenced by fluctuating water levels and associated changes in emergent vegetation. Inter-annual water level fluctuations should be considered when interpreting any indicator of wetland health that is based on marsh-dependent bird species.     

A New Biological Marker Layer in the Sediments of the Great Lakes: Bythotrephes cederstroemi (Schödler) Spines

The European cladoceran, Bythotrephes cederstroemi (Schödler), recently invaded the Laurentian Great Lakes. Based on recent zooplankton records, it most likely appeared first in 1984 in Lakes Ontario, Erie, and Huron, and in 1985 in Lake Michigan. It has yet to be reported from Lake Superior. This species is a relatively large-bodied predatory form that possesses a long, caudal, latterally barbed spine. B. cederstroemi spines and spine fragments were found in the upper fractions (predominantly 0–4 cm) of 35 sediment cores collected from seven areas of deposition in the eastern basin of Lake Erie. All remains were well preserved and easy to identify. Very few to 0 spines were found in core depths greater than 4 cm suggesting that the invasion of this species has resulted in a new, readily distinguishable time horizon marker.