Assessment of larval fish assemblages and nursery habitat in the St. Clair River delta

The St. Clair River delta, part of the St. Clair-Detroit River System (SCDRS), is the most fished coastal wetland area in the Laurentian Great Lakes and provides nursery habitat for a variety of fish species; however, few large-scale surveys of larval fish have been performed within the delta since the 1980s. Larval fish, zooplankton, and aquatic plants were sampled at 20 sites from May through July in 2010 and 2011 to characterize shallow channel and backwater delta habitats used by fish. The larval fish assemblage was sampled using active and passive gears (conical nets and light traps) and was dominated by Cyprinidae, Catostomidae, and Gobiidae. The microzooplankton assemblage was composed of rotifers, copepod nauplii, and Dreissena spp. veligers, while the macrozooplankton assemblage was composed of mostly cyclopoids and harpacticoids in May and cladocerans later in the season. Scirpus spp. dominated the plant assemblage in June and was replaced by Chara spp. in July. Seasonal compositional shifts were evident for larval fish, zooplankton, and plant assemblages, and greater densities of microzooplankton and cladocerans were typically found in backwater areas. Assemblage compositions were comparable to those in historical surveys but invasive Gobiidae and Dreissena spp. veligers now represent substantial proportions of the larval fish and zooplankton assemblages, respectively. Due to the high connectivity and advective nature of the SCDRS, understanding the larval fish assemblage dynamics of the delta can help inform estimates of system productivity.     

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.     

Telemetry reveals limited exchange of walleye between Lake Erie and Lake Huron: Movement of two populations through the Huron-Erie corridor

Immigration and emigration of individuals among populations influence population dynamics and are important considerations for managing exploited populations. Lake Huron and Lake Erie walleye (Sander vitreus) populations are managed separately although the interconnecting Huron-Erie Corridor provides an unimpeded passageway. Acoustic telemetry was used to estimate inter-lake exchange and movement within St. Clair River and Detroit River. Of 492 adult walleyes tagged and released during 2011 and 2012, one fish from Tittabawassee River (Lake Huron; 1 of 259, 0.39%) and one individual from Maumee River (Lake Erie; 1 of 233, 0.43%) exchanged lakes during 2011–2014. However, both fish returned to the lake where tagged prior to the next spawning season. The one walleye from Maumee River that moved to Lake Huron made repeated round-trips between Lake Erie and Lake Huron during three consecutive years. Of twelve fish tagged in the Tittabawassee River detected in the Huron-Erie Corridor, few (n = 3) moved south of Lake St. Clair to the Detroit River. Ten walleye tagged in the Maumee River entered the Huron-Erie Corridor, and five were detected in the St. Clair River. Our hypothesis that walleye spawning in Maumee River, Lake Erie, served as a source population to Lake Huron (“sink population”) was not supported by our results. Emigration of walleye to Lake Huron from other populations than the Maumee River, such as those that spawn on in-lake reefs, or from Lake St. Clair may contribute to Lake Huron walleye populations.     

Chlorinated Contaminants in Surficial Sediments of Lakes Huron,St. Clair,and Erie: Implications Regarding Sources Along the St. Clair and Detroit Rivers

Surficial sediments from southern Lake Huron, Lake St. Clair, and Lake Erie have been analyzed for a broad spectrum of chlorinated organics including PCBs, chlorobenzenes, and several pesticides. The differences between sediment contaminant concentrations in Lake Huron and Lake St. Clair indicated sources of hexachlorobenzene, hexachlorobutadiene, octachlorostyrene, and several other chlorinated benzenes along the St. Clair River. Similar differences between sediment PCB concentrations in Lakes Huron/St. Clair and Lake Erie indicated major PCB sources along the Detroit River. Specific PCB congener analysis revealed that PCBs discharged to the Detroit River contained especially high concentrations of highly chlorinated hexa-, hepta-, and octachloro-biphenyls which are major constituents of the industrial mixture Aroclor 1260. The analysis of individual PCB congeners made it possible to trace PCBs of Detroit River origin to the central and eastern basins of Lake Erie, and to estimate the contribution of the Detroit River to the PCB burden in sediments of these basins.     

Detroit River load estimation; the need for a new monitoring approach

The Great Lakes Water Quality Agreement (GLWQA) established new Lake Erie phosphorus loading targets, including a 40% total phosphorus load reduction to its western and central basins. The Detroit and Maumee rivers’ loads are roughly equal and contribute about 90% of the load to the western basin and 54% to the whole lake. They are key drivers of central basin hypoxia and western basin algal production. So, accurate estimates of the Detroit River load are important. Direct measurement of that load near its mouth is difficult due to requiring real-time knowledge of flows around islands and the influence of Lake Erie’s seiches. Consequently, most estimates sum the loads to the St. Clair/Detroit River system. But this approach is complicated by uncertainties in the Lake Huron load and load retention in Lake St. Clair. Routine GLWQA reassessments will confirm or adjust over time the goals, loading targets, and approaches based on evolving information. So, there is a need to improve monitoring approaches that ensure accurate Detroit River loads. New approaches should take into account both the characteristics of this dynamic connecting channel and the uses of monitoring results: 1) determining the Detroit River loads to drive models, develop mass balances, set load reduction targets, and track progress; and 2) assessing the sources and processing of the loads to help guide reduction strategies. Herein, we review temporal and spatial variability in the St. Clair/Detroit River system, and suggest adjustments to monitoring that address those variabilities and both uses.     

Macrozoobenthos of the Detroit and St. Clair Rivers with Comparisons to Neighbouring Waters

A comparison of the results from macrozoobenthic surveys of the Detroit River (1968 and 1980) showed spatial and temporal differences in the types and distribution of organisms recovered. Similar comparisons were also made from studies of the St. Clair River (1968 and 1977) and the western basin of Lake Erie (1967 and 1979). Results are also presented from a 1983 study of Lake St. Clair. These studies indicate a general improvement in the macrozoobenthos of the area, exhibited by a stronger representation of pollution sensitive organisms and an improved community structure. The studies demonstrate both the sensitivity of these large rivers and lakes and their recuperative capabilities following pollution abatement measures. Despite the documented improvements, large areas of impairment still exist, particularly in the St. Clair and Detroit rivers.     

Nutrient concentrations and loadings in the St. Clair River–Detroit River Great Lakes Interconnecting Channel

Long-term (2001–2015) water quality monitoring data for the St. Clair River are presented with data from studies in the Detroit River in 2014 and 2015 to provide the most complete information available about nutrient concentrations and loadings in the Lake Huron–Lake Erie interconnecting corridor. Concentrations of total phosphorus (TP) in the St. Clair River have reflected declines in Lake Huron. We demonstrate that St. Clair River TP concentrations are higher than offshore Lake Huron values. The recent average (2014 and 2015) incoming TP load from the upstream Great Lakes is measured here to be 980 metric tonnes per annum (MTA), which is roughly three times greater than previous estimates. Significant TP load increases are also indicated along the St. Clair River. We treat the lower Detroit River as three channels to sample water quality as part of a two year monitoring campaign that included winter sampling and SRP in the parameter suite. We found concentrations of many parameters are higher near the shorelines, with the main Mid-River channel resembling water quality upstream measured at the mouth of the St. Clair River. Comparison with past estimates indicates both concentrations and loadings of TP have dramatically declined since 2007 in the Trenton Channel, while those in the Mid-River and in the Amherstburg Channel have remained similar or have possibly increased. The data demonstrate that the TP load exiting the mouth of the Detroit River into Lake Erie is currently in the range of 3740 (in 2014) to 2610 (2015) MTA.     

Occurrence of Alkyllead Compounds in the Detroit and St. Clair Rivers

Environmental occurrence of alkyllead compounds, both of molecular species, e.g., tetraalkyllead, and ionic species, e.g., dialkyllead and trialkyllead, is believed to be derived mainly from anthropogenic sources such as effluents of alkyllead production plants and from slow degradation of tetraalkyllead in the environment. The present study describes a survey for the occurrence of tetraalkyllead, trialkyllead, dialkyllead, and Pb(II) (R = Me, Et) in water, surface microlayer, fish, and sediments from 29 stations in the St. Clair and Detroit rivers, including the western basin of Lake Erie. Results indicated that triethyllead and diethlylead compounds have been found for the first time in fish and surface microlayer in St. Clair River near Corunna where a production plant is located. About 48% of the surface microlayer samples contained various alkyllead compounds whereas only one water sample taken from the St. Clair River was found to contain alkyllead. Alkyllead compounds were found in several species of fish caught in the St. Clair River, with northern pike containing the highest concentration of alkyllead (0.173 μg/g) followed by white sucker, carp, and walleye. The concentrations of alkyllead in some individual fish reached the p.p.m. level which is considered highly hazardous for consumption although health criteria for alkyllead are not yet available. The ratios of alkyllead to total lead ranged from 0% for yellow perch and brown trout to 56% for carp.     

Updated phosphorus loads from Lake Huron and the Detroit River: Implications

The binational Great Lakes Water Quality Agreement (GLWQA) revised Lake Erie’s phosphorus (P) loading targets, including a 40% western and central basin total P (TP) load reduction from 2008 levels. Because the Detroit and Maumee River loads are roughly equal and contribute almost 90% of the TP load to the western basin and 54% to the whole lake, they have drawn significant policy attention. The Maumee is the primary driver of western basin harmful algal blooms, and the Detroit and Maumee rivers are key drivers of central basin hypoxia and overall western and central basin eutrophication. So, accurate estimates of those loads are particularly important. While daily measurements constrain Maumee load estimates, complex flows near the Detroit River mouth, along with varying Lake Erie water levels and corresponding back flows, make measurements there a questionable representation of loading conditions. Because of this, the Detroit River load is generally estimated by adding loads from Lake Huron to those from the watersheds of the St. Clair and Detroit rivers and Lake St. Clair. However, recent research showed the load from Lake Huron has been significantly underestimated. Herein, I compare different load estimates from Lake Huron and the Detroit River, justify revised higher loads from Lake Huron with a historical reconstruction, and discuss the implications for Lake Erie models and loading targets.     

First Evidence of Egg Deposition by Walleye (Sander vitreus) in the Detroit River

The importance of fish spawning habitat in channels connecting the Great Lakes to fishery productivity in those lakes is poorly understood and has not been adequately documented. The Detroit River is a reputed spawning and nursery area for many fish, including walleye (Sander vitreus) that migrate between adjacent Lakes Erie and St. Clair. During April–May 2004, near the head of the Detroit River, we collected 136 fish eggs from the bottom of the river on egg mats. We incubated the eggs at the Great Lakes Science Center until they hatched. All eleven larvae that hatched from the eggs were identified as walleye. These eggs and larvae are the first credible scientific evidence that walleye spawn in the Detroit River. Their origin might be a stock of river-spawning walleye. Such a stock of walleye could potentially add resilience to production by walleye stocks that spawn and are harvested in adjacent waters.     

Organochlorine and Mercury Residues in Young-of-the-Year Spottail Shiners from the Detroit River,Lake St. Clair,and Lake Erie

Young-of-the-year spottail shiners (Notropis hudsonius) were used as biomonitors to determine the spatial distribution (1982/83) and assess trend data for organochlorine and mercury residues. Significantly (p < 0.01) higher PCB residues were found in Detroit River spottail shiners than in collections from southwestern Lake St. Clair and northwestern Lake Erie. The highest PCB residues were found in the west bank collections from Michigan waters (912–2,997ng/g) compared to the mid-stream (96–290 ng/g) and east bank collections (153–316 ng/g). Chlordane residues were found to be elevated in all spottail shiner samples from urbanized areas. Octachlorostyrene and ∑ DDT residues were distributed uniformly within the study area, whereas mercury concentrations were found to be lower in spottail shiners from northwestern Lake Erie than in comparable samples from the Detroit River and southwestern Lake St. Clair. Residues for BHC, heptachlor, aldrin, and chlorinated benzenes were near their detection limits; mirex and chlorinated phenols were not detectable. Recent (1982/83) PCB residue levels in spottail shiners exceeded the IJC aquatic life objective (Great Lakes Water Quality Agreement of 1978) at all the sites sampled, except at Pike Creek in Lake St. Clair. PCB residues in spottail shiners from Pike Creek, Big Creek, and Leamington have declined significantly (p < 0.01) since the mid-seventies. Mercury and chlordane residues have decreased in spottail shiner samples from Leamington, but have remained virtually unchanged at Big Creek and Pike Creek.     

Temporal Effects of St. Clair River Dredging on Lakes St. Clair and Erie Water Levels and Connecting Channel Flow

A Great Lakes hydrologic response model was used to study the temporal effects of St. Clair River dredging on Lakes St. Clair and Erie water levels and connecting channel flows. The dredging has had a significant effect on Great Lakes water levels since the mid-1980s. Uncompensated dredging permanently lowers the water levels of Lakes Michigan and Huron and causes a transitory rise in the water levels of Lakes St. Clair and Erie. Two hypothetical dredging projects, each equivalent to a 10 cm lowering of Lakes Michigan and Huron, were investigated. This lowering is approximately half the effect of the 7.6 and 8.2 meter dredging projects. In the first case the dredging was assumed to occur over a single year while in the second it was spread over a 2-year period. The dredging resulted in a maximum rise of 6 cm in the downstream levels of Lakes St. Clair and Erie. The corresponding increase in connecting channel flows was about 150 m³s^?1. The effects were found to decrease over a 10-year period with a half-life of approximately 3 years. The maximum effects on Lake Erie lagged Lake St. Clair by about 1 year.     

Temporal and spatial trends of organochlorines and mercury in fishes from the St. Clair River/Lake St. Clair corridor,Canada

The temporal and spatial relationships of a suite of organochlorine contaminants and mercury were examined in various fish species of the St. Clair River/Lake St. Clair corridor, Canada, in order to evaluate the effectiveness of remediation efforts and to assess the risk to human and wildlife fish consumers. In Lake St. Clair, fish tissue concentrations of mercury, polychlorinated biphenyls (PCBs), octachlorostyrene (OCS), hexachlorobenzene (HCB), and dichlorodiphenyltrichloroethane (DDT) decreased consistently from the 1970s until the 1980s and 1990s, after which the rate of contaminant decline slowed or concentrations stabilized. This trend was consistent in up to 13 species (both young-of-the-year and adult fishes) comprising different trophic positions and dietary habits, suggesting that the changes were reflective of ambient conditions rather than food web processes. Elevated concentrations of mercury, PCBs, OCS, HCB, and DDT were detected in St. Clair River young-of-the-year spottail shiner compared with fish from Lake Huron, indicating that non-atmospheric inputs of these chemicals, likely originating from sediment, remain in the St. Clair River. Current concentrations of mercury and PCBs, and mercury, PCBs, and DDT remain of concern to human and wildlife fish consumers, respectively. Given that contaminant decreases have generally stabilized in fish, we suggest that further natural recovery of contaminants in St. Clair corridor fishes will be slow since contaminants will likely continue to be influenced by sediment levels.     

Distribution and Abundance of Zooplankton in the U.S. Waters of Lake St. Clair, 1973

Zooplankton were obtained in the U.S. waters of Lake St. Clair at 28 stations sampled monthly from July through September 1973. Distribution and abundance of zooplankton were compared with physicochemical data collected concurrently and with previous studies on Lake St. Clair zooplankton.Sixty five species of Rotifera were recorded. Brachionus angularis, Conochilus unicornis and Synchaeta stylata were the three most abundant species. Total rotifers, averaging 47.1 individuals per liter over the study period, were about 30 times more abundant than the micro-crustaceans. The Cladocera were represented by 28 species, while five species of cyclopoids, seven calanoids and four harpacticoids were recorded from the Copepoda. Bosmina longirostris was the predominant micro-crustacean.Spatial distribution of zooplankton was hypothesized to be primarily dependent on current patterns generated by prevailing winds. The Canadian portion of the lake has a persistent eddy structure which apparently allows build-up of nutrient levels encouraging high zooplankton biomass. The U.S. side, however, experiences more rapid flow-through of St. Clair River water which accounts for lower zooplankton abundance. Despite the fast flushing rate on the U.S. side, a localized patch of high zooplankton density and a community structure indicative of eutrophic situations was consistently observed off the Clinton River Cutoff Canal. This is presumably due to nutrient loading from the Clinton River watershed.     

Wind Stress Effects on Detroit River Discharges

Dynamic flow models are currently used to compute Detroit River discharges for hourly, daily, and monthly time scales. These models include the complete one-dimensional equations of continuity and motion, but neglect the effects of wind stress and ice. The effects of wind stress upon calculated daily and monthly Detroit River discharges are analyzed. The wind effects of several storms with wind setups and surges on Lake Erie were evaluated on an hourly time scale. Inclusion of wind stress terms into the Detroit River models was found to have no significant effect on the monthly flow calculations and on the majority of the daily flow calculations. However, the average monthly effect of ?47 m³ s^?1 is equivalent to 111 mm depth of water per month on Lake St. Clair, which may be significant for some Lake St. Clair water balance studies. The effect on Lake Erie is on the order of 5 mm of depth per month, which is not significant for water balance studies. The wind stress was found to be important for daily and hourly flow computations when wind velocities were in excess of about 6 m s^?1.     

Aromatic Hydrocarbons in Biota from the Detroit River and Western Lake Erie

Polynuclear aromatic hydrocarbons (PAHs) and PCBs in zebra mussels were elevated to concentrations greater than 5,000 ng/g lipid and 15,000 ng/g lipid, respectively, at the Ambassador Bridge in the Detroit River and concentrations gradually declined at downstream locations, which included three stations in the western basin of Lake Erie (Middle Sister Island, East Sister Island, Pelee Island). PCB concentrations in zebra mussels collected at the stations in western Lake Erie were elevated relative to the concentrations in mussels at the upstream end of the Detroit River (Stoney Point). There is no evidence that PAH contamination in the Detroit River elevated PAH concentrations in zebra mussels in western Lake Erie relative to mussels at Stoney Point. Fluorescent aromatic compounds (FACs) representing metabolites of PAHs were analyzed in the bile of gizzard shad (Dorosoma cepedianum) and freshwater drum (Aplodinotus grunniens) collected from several sites in the Detroit River and western Lake Erie. Mean FAC concentrations were >l,000 ng BaP equivalents per mL of bile in fish from the Trenton Channel and Boblo Island in the Detroit River, but FAC data provided no evidence that fish captured at two sites in western Lake Erie (East Sister Island, Pelee Island) were exposed to elevated concentrations of PAHs through ingestion of contaminated biota or exposure to contaminated sediments.     

Relative abundance,age structure,and body size in mudpuppy populations in southwestern Ontario

Little is known of mudpuppy (Necturus maculosus) population structure and ecology; some populations in the Great Lakes are thought to be in decline. Mudpuppies are the obligate hosts for the mudpuppy mussel (Simpsonaias ambigua), a species that is endangered in Canada and in many Great Lakes states. We surveyed mudpuppies from the Sydenham River, the only known Canadian locality of the mudpuppy mussel, in order to generate information on relative density, deformity rates and population age/size structure and used this information to compare them to known mudpuppy populations from Great Lakes sites in the Detroit River, Lake St. Clair and Long Point in Lake Erie. Deformity rates were elevated at some sites in the Sydenham River. The relative density of mudpuppies in the Sydenham River was lower than that of other Great Lakes sites and their age was skewed towards younger individuals. Although at lower densities than at other Great Lakes sites, the mudpuppy population in the Sydenham River appears stable and is showing signs of recruitment which bodes well for the future of the mudpuppy mussel population of the river.     

Flow Distribution in Selected Branches of St. Clair and Detroit Rivers

St. Clair and Detroit rivers, which are connecting channels between Lake Huron and Lake Erie in the Great Lakes basin, form part of the boundary between the state of Michigan and the province of Ontario. In 13 reaches, this flow divides locally around islands and dikes to form 31 branches. This study develops a set of simple linear regression equations for computing expected flow proportions in branches, generally as a function of the total flow within the reach. The equations are based on 533 acoustic Doppler current profiler measurements of flow obtained between 1996 and 2000. Root-mean-square errors of these regressions range from 0.00323 to 0.0895. In seven upstream reaches where flow is known because of flow specifications at the boundaries of the waterway and continuity constraints, the uncertainties of the flow proportions can be used to directly infer the uncertainties of the corresponding flows. In six downstream reaches, the uncertainties of flows are determined by both the uncertainties of the flow proportions and the uncertainties of the total flow in the reach. For these reaches, Monte Carlo simulations quantify the ratios of total uncertainty to flow proportion uncertainty, which range from 1.0026 to 13.984. To facilitate routine calculation, polynomial regression equations are developed to approximate these ratios as a function of flow. Results provide a mechanism for computing the magnitudes and uncertainties of steady-state flows within selected branches of the connecting channels by specifying inflows at the headwaters of St. Clair River, seven intervening tributaries, and Lake St. Clair.     

First Record of Corophium mucronatum Sars (Crustacea: Amphipoda) in the Great Lakes

Corophium mucronatum Sars, a small amphipod native to the Caspian and Black Sea basins, was discovered in September 1997 in Lake St. Clair. A single individual was collected using a bottom sled dredge in littoral waters adjacent to Seaway Island, Ontario. The specimen was found on silty-sand substrate in an area populated by submerged macrophytes. Because no other Corophium individuals were found despite repeated sampling over two years at a total of 60 sites in the corridor between the St. Clair River and western Lake Erie, it is highly unlikely that this species has established in the Great Lakes.     

Evidence of Lake Whitefish Spawning in the Detroit River: Implications for Habitat and Population Recovery

Historic reports imply that the lower Detroit River was once a prolific spawning area for lake whitefish (Coregonus clupeaformis) prior to the construction of the Livingstone shipping channel in 1911. Large numbers of lake whitefish migrated into the river in fall where they spawned on expansive limestone bedrock and gravel bars. Lake whitefish were harvested in the river during this time by commercial fisheries and for fish culture operations. The last reported landing of lake whitefish from the Detroit River was in 1925. Loss of suitable spawning habitat during the construction of the shipping channels as well as the effects of over-fishing, sea lamprey (Petromyzon marinus) predation, loss of riparian wetlands, and other perturbations to riverine habitat are associated with the disappearance of lake whitefish spawning runs. Because lake whitefish are recovering in Lake Erie with substantial spawning occurring in the western basin, we suspected they may once again be using the Detroit River to spawn. We sampled in the Detroit River for lake whitefish adults and eggs in late fall of 2005 and for lake whitefish eggs and fish larvae in 2006 to assess the extent of reproduction in the river. A spawning-ready male lake whitefish was collected in gillnets and several dozen viable lake whitefish eggs were collected with a pump in the Detroit River in November and December 2005. No lake whitefish eggs were found at lower river sites in March of 2006, but viable lake whitefish eggs were found at Belle Isle in the upper river in early April. Several hundred lake whitefish larvae were collected in the river during March through early May 2006. Peak larval densities (30 fish/1,000 m³ of water) were observed during the week of 3 April. Because high numbers of lake whitefish larvae were collected from mid-and downstream sample sites in the river, we believe that production of lake whitefish in the Detroit River may be a substantial contribution to the lake whitefish population in Lake Erie.