Changes in the Dreissenid Community in the Lower Great Lakes with Emphasis on Southern Lake Ontario

A field study was conducted in the lower Great Lakes to assess changes in spatial distribution and population structure of dreissenid mussel populations. More specifically, the westward range expansion of quagga mussel into western Lake Erie and toward Lake Huron was investigated and the shell size, density, and biomass of zebra and quagga mussel with depth in southern Lake Ontario in 1992 and 1995 were compared. In Lake Erie, quagga mussel dominated the dreissenid community in the eastern basin and zebra mussel dominated in the western basin. In southern Lake Ontario, an east to west gradient was observed with the quagga mussel dominant at western sites and zebra mussel dominant at eastern locations. Mean shell size of quagga mussel was generally larger than that of zebra mussel except in western Lake Erie and one site in eastern Lake Erie. Although mean shell size and our index of numbers and biomass of both dreissenid species increased sharply in southern Lake Ontario between 1992 and 1995, the increase in density and biomass was much greater for quagga mussels over the 3-year period. In 1995, zebra mussels were most abundant at 15 to 25 m whereas the highest numbers and biomass of quagga mussel were at 35 to 45 m. The quagga mussel is now the most abundant dreissenid in areas of southern Lake Ontario where the zebra mussel was once the most abundant dreisenid; this trend parallels that observed for dreissenid populations in the Dneiper River basin in the Ukraine.     

Dreissenid mussels are not a “dead end” in Great Lakes food webs

Dreissenid mussels have been regarded as a “dead end” in Great Lakes food webs because the degree of predation on dreissenid mussels, on a lakewide basis, is believed to be low. Waterfowl predation on dreissenid mussels in the Great Lakes has primarily been confined to bays, and therefore its effects on the dreissenid mussel population have been localized rather than operating on a lakewide level. Based on results from a previous study, annual consumption of dreissenid mussels by the round goby (Neogobius melanostomus) population in central Lake Erie averaged only 6 kilotonnes (kt; 1 kt = one thousand metric tons) during 1995–2002. In contrast, our coupling of lake whitefish (Coregonus clupeaformis) population models with a lake whitefish bioenergetics model revealed that lake whitefish populations in Lakes Michigan and Huron consumed 109 and 820 kt, respectively, of dreissenid mussels each year. Our results indicated that lake whitefish can be an important predator on dreissenid mussels in the Great Lakes, and that dreissenid mussels do not represent a “dead end” in Great Lakes food webs. The Lake Michigan dreissenid mussel population has been estimated to be growing more than three times faster than the Lake Huron dreissenid mussel population during the 2000s. One plausible explanation for the higher population growth rate in Lake Michigan would be the substantially higher predation rate by lake whitefish on dreissenid mussels in Lake Huron.     

Distribution,seasonality and putative origin of the non-native red alga Bangia atropurpurea (Bangiales,Rhodophyta) in the Laurentian Great Lakes

Bangia atropurpurea was first observed in Lake Erie in 1964 and subsequently spread to the lower Laurentian Great Lakes by the mid to late 1970s. The present study was initiated to examine the recent distribution of B. atropurpurea in the Great Lakes, the seasonal variation of the alga and the putative origin of this species based on DNA sequence analysis. From surveys in 1995 and 2002, this species has clearly spread, with newly identified populations observed in Lakes Huron, Michigan, Georgian Bay and the St. Lawrence River. Morphological analyses showed that Great Lakes populations from individual lakes or neighboring populations did not group together in cluster analyses. Correlation analysis, however, revealed significant relationships between the presence or absence of Bangia among the studied sites with pH and specific conductance as those locations that had stable populations had a mean pH and conductance of 8.2 and 353 μS·cm^− 1 respectively. Seasonal variation in morphology of a population from Burlington, Ontario (Lake Ontario, Canada) was examined monthly for one year. Maximum filament length occurred in April, with the greatest diameter and archaeospore production observed in May. Significant correlations were also noted for many morphological characteristics with water temperature, population height on the shoreline relative to the waterline and total phosphorus. Collections of B. atropurpurea analyzed from the Great Lakes were observed to be identical in sequence to collections of European freshwater Bangia in the cox2–3 gene spacer, the nuclear internal transcribed spacers (ITS 1 and 2) and the 5.8S rRNA gene (between the small and large subunits of the rRNA gene). These results suggest a recent European origin; however, further global collections of B. atropurpurea and microsatellite analyses are necessary to confirm this hypothesis.     

Genetic population structure of cisco,Coregonus artedi,in the Laurentian Great Lakes

Management of a widely distributed species can be a challenge when management priorities, resource status, and assessment methods vary across jurisdictions. For example, restoration and preservation of coregonine species diversity is a goal of management agencies across the Laurentian Great Lakes. However, management goals and the amount of information available varies across management units, making the focus for management efforts challenging to determine. Genetic data provide a spatially consistent means to assess diversity. Therefore, we examined the genetic stock structure of cisco (Coregonus artedi) in the Great Lakes where the species is still extant. Using genotype data from 17 microsatellite DNA loci, we observed low levels of population structure among collections with most contributions to overall diversity occurring among lakes. Cisco from lakes Superior, Michigan, Ontario, and the St. Marys River could be considered single genetic populations while distinct genetic populations were observed among samples from northern Lake Huron. Significant within-lake diversity in Lake Huron is supported by populations found in embayments in northern Lake Huron. The Grand Traverse Bay population in Lake Michigan represents a distinct population with reduced levels of genetic variation when compared to other lakes. The different levels of within lake population structure we observed will be important to consider as future lake-specific management plans are developed.     

Population genetic diversity and phylogeographic divergence patterns of the yellow perch (Perca flavescens)

Great Lakes populations of yellow perch have fluctuated throughout past decades to the present due to unstable recruitment patterns and exploitation. Our study analyzes genetic diversity and structure across the native range in order to interpret phylogeographic history and contemporary patterns. We compare complete mitochondrial DNA control region sequences (912 bp) from 568 spawning individuals at 32 sites, encompassing all 5 Great Lakes and outlying watersheds from the upper Mississippi River, Lake Winnipeg, Lake Champlain, and Atlantic and Gulf coastal relict populations. These broad-scale divergences additionally are compared with fine-scale patterns from 334 individuals at 16 spawning sites across Lake Erie's 4 fishery management units. We identify 21 mtDNA haplotypes, including a widespread type that totals 87% of individuals across the Great Lakes. Overall genetic diversity is relatively low in comparison with other Great Lakes fishes, congruent with prior allozyme and microsatellite studies. The largest genetic demarcation separates 2 primary population groups: one in the Great Lakes, Lake Winnipeg, and upper Mississippi River watersheds and the other along the Atlantic and Gulf coasts, together with Lake Champlain; which diverged ∼ 365,000 years ago. In addition, the watersheds house genetically separable groups, whose patterns reflect broad-scale isolation by geographic distance. A few spawning groups show some fine-scale differentiation within Lake Erie, which do not reflect fishery management units and need further study with higher-resolution markers.     

Diets,population structure,and seasonal activity patterns of mudpuppies (Necturus maculosus) in an urban,Great Lakes coastal habitat

Freshwater species native to the Laurentian Great Lakes region face numerous environmental stressors, and the conservation status and ecological relationships of many remain poorly understood. One such species, the mudpuppy (Necturus maculosus), is declining, but better information on their natural history and development of more effective population monitoring techniques is needed. We assessed seasonal variation in capture success, biases in capture techniques, and feeding ecology of mudpuppies in Wolf Lake, a highly perturbed and urban former estuarine wetland complex to Lake Michigan. Trapping periods of ≥ 3 consecutive nights occurred from January to May 2015, and October 2015 to March 2016. Overall trapping success differed among trapping periods (p = 0.01) and declined precipitously at water temperatures above 14.1 °C (p < 0.001). Mudpuppies in traps (mean 26.9 ± 0.5 cm) were larger than those caught with hand nets (mean 14.7 ± 0.8 cm, p < 0.0001), suggesting that multiple methods may be needed to accurately assess demographics. Stomach contents obtained through gastric lavage included mollusks, leeches, insects, isopods, amphipods, crayfish, fish, a frog, and a juvenile conspecific. Invasive species, including rusty crayfish (Orconectes rusticus), round gobies (Neogobius melanostomus), and zebra/quagga mussels (Dreissena spp.) were present in guts, suggesting mudpuppy foraging has changed along with aquatic communities in the region. Prey community analyses revealed differences in overall diet among size classes of mudpuppies (p = 0.001), but relatively weak similarity within size classes. Results suggest that mudpuppies in lake ecosystems occupy a broad niche that changes as they grow.     

Lake-wide Distribution of Dreissena in Lake Michigan, 1999

The Great Lakes Science Center has conducted lake-wide bottom trawl surveys of the fish community in Lake Michigan each fall since 1973. These systematic surveys are performed at depths of 9 to 110 m at each of seven index sites around Lake Michigan. Zebra mussel (Dreissena polymorpha) populations have expanded to all survey locations and at a level to sufficiently contribute to the bottom trawl catches. The quagga (Dreissena bugensis), recently reported in Lake Michigan, was likely in the catches though not recognized. Dreissena spp. biomass ranged from about 0.6 to 15 kg/ha at the various sites in 1999. Dreissenid mussels were found at depths of 9 to 82 m, with their peak biomass at 27 to 46 m. The colonization of these exotic mussels has ecological implications as well as potential ramifications on the ability to sample fish consistently and effectively with bottom trawls in Lake Michigan.     

Abundance and distribution of benthic macroinvertebrates in offshore soft sediments in Western Lake Huron, 2001–2007

Invasive species have had major impacts on the Great Lakes. This is especially true of exotic dreissenid mussels which are associated with decreased abundance of native macroinvertebrates and changes in food availability for fish. Beginning in 2001, we added a benthic macroinvertebrate survey to the USGS-Great Lakes Science Center's annual fall prey fish assessment of Lake Huron to monitor abundance of macrobenthos. Mean abundance of Diporeia, the most abundant benthic taxon in Lake Huron reported by previous investigators, declined greatly between 2001 and 2007. Diporeia was virtually absent at 27-m sites by 2001, decreased and was lost completely from 46-m depths by 2006, but remained present at reduced densities at 73-m sites. Dreissenids in our samples were almost entirely quagga mussels Dreissena bugensis. Zebra mussels Dreissena polymorpha were virtually absent from our samples, suggesting that they were confined to nearshore areas shallower than we sampled. Loss of Diporeia at individual sites was associated with arrival of quagga mussels, even when mussel densities were low. Quagga mussel density peaked during 2002, then decreased thereafter. During the study quagga mussels became established at most 46-m sites, but remained rare at 73-m sites. Length frequency distributions suggest that initial widespread recruitment may have occurred during 2001–2002. Like other Great Lakes, Lake Huron quagga mussels were associated with decreased abundance of native taxa, but negative effects occurred even though dreissenid densities were much lower. Dreissenid effects may extend well into deep oligotrophic habitats of Lake Huron.     

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.     

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.     

Replacement of Zebra Mussels by Quagga Mussels in the Canadian Nearshore of Lake Ontario: the Importance of Substrate,Round Goby Abundance,and Upwelling Frequency

The invasion of the Great Lakes by zebra mussels (Dreissena polymorpha) and quagga mussels (Dreissena bugensis) has been accompanied by tremendous ecological change. In this paper we characterize the extent to which dreissenids dominate the nearshore of the Canadian shoreline of Lake Ontario and examine mussel distribution in relation to environmental factors. We surveyed 27 5-m sites and 25 20-m sites in late August 2003. Quagga mussels dominated all sites (mean: 9,404/m²; range 31–24,270), having almost completely replaced zebra mussels. Round gobies (Neogobius melanostomus) were associated with quagga populations dominated by large mussels. Quagga mussel total mass was low at 5-m sites with high upwelling frequency; we believe this is the first documentation of reduced benthic biomass in areas of upwelling in Lake Ontario. Overall, we estimated 6.32×10¹² quagga mussels weighing 8.13×10¹¹ g dry weight and carpeting ∼66% of the nearshore benthic habitat. Quagga mussels are a dominant and defining feature of the Lake Ontario nearshore, and must be accounted for in management planning.     

Trends in Diporeia populations across the Laurentian Great Lakes, 1997-2009

Benthic communities in the Laurentian Great Lakes have been in a state of flux since the arrival of dreissenid mussels, with the most dramatic changes occurring in population densities of the amphipod Diporeia. In response, the US EPA initiated an annual benthic macroinvertebrate monitoring program on all five Great Lakes in 1997. Although historically the dominant benthic invertebrate in all the lakes, no Diporeia have been found in Lake Erie during the first 13 years of our study, confirming that Diporeia is now effectively absent from that lake. Populations have almost entirely disappeared from our shallow (< 90 m) sites in lakes Ontario, Huron, and Michigan. In Lake Ontario, three of our four deep (> 90 m) sites still supported Diporeia populations in 2009, with densities at those sites ranging between 96 and 198/m². In Lake Michigan, populations were still found at six of our seven deep sites in 2009, with densities ranging from 57 to 1409/m². Densities of Diporeia in 2009 at the four deep sites in Lake Huron were somewhat lower than those in Lake Michigan, ranging from 191 to 720/m². Interannual changes in population size in Lake Huron and Lake Michigan have shown a degree of synchrony across most sites, with periods of rapid decline (1997-2000, 2003-2004) alternating with periods of little change or even increase (2001-2002, 2005-2009). There has been no evidence of directional trends at any sites in Lake Superior, although substantial interannual variability was seen.     

NOTE: First record of natural reproduction by Atlantic salmon (Salmo salar) in the St. Marys River,Michigan

Atlantic salmon (Salmo salar) are native to Lake Ontario; but their populations severely declined by the late 1800s due to human influences. During the early to mid-1900s, Atlantic salmon were stocked throughout the Great Lakes in effort to reestablish them into Lake Ontario and introduce the species into the upper Great Lakes. However, these efforts experienced minimal success. In 1987, Lake Superior State University and the Michigan Department of Natural Resources began stocking Atlantic salmon in the St. Marys River, Michigan, which has resulted in a successful, self-supporting hatchery operation and stable recreational Atlantic salmon fishery. Possibly due to a combination of competition with other salmonid species for spawning habitat, prey selection causing detrimental effects on early life stages and high rates of early mortality syndrome, Atlantic salmon appeared to be severely limited in their ability to naturally reproduce within the upper Great Lakes. In 2012, the first unequivocal documentation of naturally reproduced Atlantic salmon in the St. Marys River was recorded, downstream from the compensation works and parallel to the Soo Locks in Sault Ste. Marie, Michigan.     

Distribution of nuisance Cladophora in the lower Great Lakes: Patterns with land use, near shore water quality and dreissenid abundance

Selected shorelines and offshore shoals in Lakes Erie, Huron and Ontario were surveyed with a high frequency hydroacoustic system to investigate current spatial patterns of nuisance benthic filamentous algal (e.g., Cladophora) cover and stand height. Cladophora reached nuisance levels at all sites in Lakes Erie and Ontario, but not in Lake Huron or Georgian Bay. Despite clear gradients in coastal land cover, near shore water quality gradients were generally weak, and for Lakes Erie and Ontario, measures of near shore water quality were similar to that at offshore shoals. Hierarchical partitioning analysis suggested that while dreissenid mussel abundance appeared to be important in determining the magnitude of Cladophora standing crop, the joint contribution of catchment land cover, near shore water quality (nutrient levels and suspended matter) and dreissenid mussel abundance explained nearly 95% of the total variance in nuisance Cladophora standing crop observed in this study. Although the results from this study are necessarily correlative in nature and definition of causal relationships is not possible, these results provide corroborating evidence from sites across a gradient within and across the lower Great Lakes that is consistent with the operation of the near shore shunt model.     

European Valve Snail Valvata piscinalis (Müller) in the Laurentian Great Lakes Basin

Previously reported from the lower Great Lakes basin and St. Lawrence and Hudson rivers, the nonindigenous gastropod Valvata piscinalis was found for the first time in Superior Bay (Minnesota) of Lake Superior, Lake Michigan (Wisconsin), and Oneida Lake (New York) of the Lake Ontario basin. This snail was not abundant in Lakes Superior and Michigan, whereas in eutrophic Oneida Lake it reached a maximum density of 1,690 individuals/m² (mean density = 216 individuals/m²). Human-mediated disturbances could facilitate the range extension of this snail by providing dispersal opportunities (e.g., canals, shipping traffic) or increasing nutrients (e.g., eutrophication). A native of the Palaearctic region, V. piscinalis has colonized sites across the Great Lakes basin, suggesting that it will likely become common in disturbed Great Lakes areas.     

Environmental exposure of freshwater mussels to contaminants of emerging concern: Implications for species conservation

Contaminants of emerging concern (CECs) are prevalent in aquatic landscapes and may be a factor in population declines of aquatic and terrestrial fauna. Yet, there are limited data to assess the impacts of CECs to species. Understanding CEC impacts is particularly important for imperiled freshwater mussels which provide valuable ecosystem services. CEC exposure of freshwater mussels was characterized by evaluating sites with and without the federally endangered mussel (Villosa fabalis) in three subwatersheds of the Maumee River, Ohio, USA, a tributary of the Great Lakes Basin. Analyses of water, sediment, and tissue concentrations of two common mussels (Eurynia dilatata and Lampsilis cardium) indicated different CEC exposures across all 6 sites. Distinct CEC signatures were found across the three media types suggesting as mussels interact with water and sediment they may be experiencing different exposure concentrations and mixtures of CECs at different life stages. Of the 83 CECs which were detected, agricultural CECs dominated sediments, pharmaceuticals were common in tissues and water, and 16 of the 83 CECs were found co-occurring in mussel tissue, water, and sediment. There were no species differences in the CEC signatures indicating all mussels, including species of concern, may be experiencing similar exposure. Comparisons to known CEC standards indicate some exceedances in the Maumee watershed including locations of federally listed mussel species. This study provides evidence of the complexity of CEC mixes in a Great Lakes watershed and the need to understand how CECs impact declining aquatic fauna.     

Impacts of predation by the Eurasian round goby (Neogobius melanostomus) on molluscs in the upper St. Lawrence River

An invasive Eurasian fish, the round goby Neogobius melanostomus, has recently spread from the Great Lakes into the St. Lawrence River. We quantified prey preferences of this benthivore and determined whether its predatory impacts on molluscs in the river are similar to those in the Great Lakes. We measured the size structure of gastropods and dreissenid mussels at 13 St. Lawrence River sites where round goby densities ranged from 0 to 6 m^− 2. For four of these sites, data were available for multiple years before and after invasion. Contrary to studies in the Great Lakes, there were no consistent effects of round goby density on the size structure of dreissenids, although there was an ontogenetic diet shift toward dreissenids. However, the abundance and richness of small gastropods (≤ 14 mm) was negatively correlated with round goby density across all sites, and declined over time at three of four sites sampled before and after invasion. Median gastropod size also declined across sites with increasing round goby density. Gastropods (as well as chironomid larvae, caddisfly larvae, and ostracods) were consistently among the most preferred prey items consumed by gobies, whereas dreissenids (as well as leeches and freshwater mites) were consistently avoided. These results indicate the major role of the round goby in structuring gastropod populations in the St. Lawrence River, and highlight large-scale spatial variation in its predatory impact on dreissenid populations.     

Status of the major aquaculture carps of China in the Laurentian Great Lakes Basin

There is concern of economic and environmental damage occuring if any of the four major aquacultured carp species of China, black carp Mylopharyngodon piceus, bighead carp Hypophthalmichthys nobilis, silver carp H. molitrix, or grass carp Ctenopharyngodon idella, were to establish in the Laurentian Great Lakes. All four are reproducing in the Mississippi River Basin. We review the status of these fishes in relation to the Great Lakes and their proximity to pathways into the Great Lakes, based on captures and collections of eggs and larvae. No black carp have been captured in the Great Lakes Basin. One silver carp and one bighead carp were captured within the Chicago Area Waterway System, on the Great Lakes side of electric barriers designed to keep carp from entering the Great Lakes from the greater Mississippi River Basin. Three bighead carp were captured in Lake Erie, none later than the year 2000. By December 2019, at least 650 grass carps had been captured in the Great Lakes Basin, most in western Lake Erie, but none in Lake Superior. Grass carp reproduction has been documented in the Sandusky and Maumee rivers in Ohio, tributaries of Lake Erie. We also discuss environmental DNA (eDNA) results as an early detection and monitoring tool for bighead and silver carps. Detection of eDNA does not necessarily indicate presence of live fish, but bigheaded carp eDNA has been detected on the Great Lakes side of the barriers and in a small proportion of samples from the western basin of Lake Erie.     

Changes in Benthic Invertebrate Communities of South Bay,Lake Huron Following Invasion by Zebra Mussels (Dreissena polymorpha), and Potential Effects on Lake Whitefish (Coregonus clupeaformis) Diet and Growth

In this study we evaluated changes in benthic invertebrate communities of South Bay, Lake Huron following the invasion of zebra mussels (Dreissena polymorpha) and considered the implications for diets and growth of whitefish (Coregonus clupeaformis), a commercially important fish in the Great Lakes. Of the ten benthic invertebrate groups identified prior to invasion (1980–81), only densities of Diporeia and Oligochaeta have changed since the appearance of the zebra mussel, and only Diporeia and Chironomidae changed in relative abundance. These changes are similar to those observed in other areas of the Great Lakes, with the exception of an increase in Oligochaeta density. Post-invasion (2002–03) shallow-water communities appear to be more homogeneous, dominated by zebra mussels and Isopoda, whereas deep-water sites are more heterogeneous due to the loss of Diporeia. Additional data on Diporeia density for several years between 1959 and 2004 indicated that current low densities are not typical of South Bay. Based on changes in the benthic communities and published literature on whitefish diets, we predict that unless whitefish are able to switch to Mysis as an alternative to Diporeia, post-invasion whitefish diets will only contain a maximum of 57 to 84% of their former energy content. These predictions are likely underestimates, as they do not take into account increased energy costs associated with reductions in total invertebrate density at historical foraging depths.