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In 2017, we conducted a lake-wide benthic survey at 129 stations to assess the status of the benthic macroinvertebrate community in all major basins of Lake Huron, with a primary focus on the invasive zebra mussels (Dreissena polymorpha) and quagga mussels (D. rostriformis bugensis), and to compare the current benthic community with historic data. We found that quagga mussels were most abundant in the main basin, less common in Georgian Bay and almost absent in North Channel. Comparing the 2017 findings to 2012 data, Dreissena density in the main basin in the shallowest (<30 m) depth zone declined by a factor of seven, remained stable at 30-90 m, and more than doubled at depths greater than 90 m. As a result, the bulk of population is now found deeper than 50 m. Diporeia and Sphaeriidae densities continued to decline in all basins including North Channel, where almost no quagga mussels were found. In contrast, in 2017 there was a substantial increase in oligochaetes in all regions compared to the 1970s and 2000s, likely due to an increase in their food resources as associated with quagga mussel feeding activities. These data were recently submitted to GLNPO; data analysis is ongoing and will be summarized in a report and a publication. (2017-2019)
Lake Huron Benthos Survey report 2017 (PDF, 1MB)
Photo gallery: CSMI Lake Huron 2017
In September 2016, the GLC conducted a lake-wide nearshore benthic survey of Lake Superior as part of the CSMI to assess the status of the macroinvertebrate community with a focus on temporal trends. Benthic samples were collected at 59 nearshore stations, 25 of which were previously sampled in 1994, 2000, and 2003 (Scharold et al., 2009), and the rest were new locations selected using a GRTS sampling design. The most common benthic taxon by density in 2016 was Diporeia, followed by Oligochaeta, Sphaeriidae, and Chironomidae, comparable to the structure found in previous studies. Lake-wide, 94% of the 59 sampling stations in 2016 had high Diporeia densities. However, we found a significant decline of Diporeia densities in 2016 compared to 1994 at 95% of the 25 previously sampled stations, and Diporeia were not collected at three of these stations. In contrast to other Great Lakes, Dreissena spp. have not established a sizable population in Lake Superior and therefore cannot account for the decline in Diporeia abundance, suggesting that benthivorous fish predation or other environmental factors might have caused the changes. This apparent decline in nearshore Diporeia density could be an indication of a long-term trend of decreasing their densities or could be a result of inter-annual variation, reinforcing the importance of frequent monitoring to detect statistically significant temporal trends. Oligochaeta, Sphaeriidae and Chironomidae declined at some of the stations in 2016 compared to 1994, but the changes were not significant. The survey was conducted with the assistance of EPA GLNPO and in collaboration with EPA Mid-Continent Ecology Division (Duluth). This effort was funded by EPA through USGS (PIs Karatayev and Burlakova). (2016-2018)
Lake Superior Benthos Final Report (PDF, 1MB)
Photo galleries: Great Lakes Benthos Monitoring 2016
In 2015, in collaboration with the U.S. EPA, University of Michigan, and NOAA, we conducted the first lake-wide survey of the benthic community of Lake Michigan after the Dreissena spp. invasion. We collected and analyzed 421 PONAR samples from 143 sites located in all basins of the lake, and depths ranged from 10 to 196 m. Over 110 different macroinvertebrate taxa were found in the lake, with Chironomidae and Oligochaeta being the most diverse taxonomic groups. Perhaps the most significant finding in 2015 was the decline in densities of D. r. bugensis at depths < 90 m, while the biomass remained stable or slightly increased compared to 2010. In contrast, both density and biomass of Dreissena at > 90 m increased. Dreissena polymorpha has essentially been displaced by D. r. bugensis and was not found in 2015. The amphipod Diporeia continued to disappear. It was not collected at any sites < 90 m and only at 9 sites > 90 m. Molluscs Sphaeriidae progressively declined as well all depth intervals between 1992 and 2015. Based on comparisons to data collected in the southern basin in 1992-1993 and 1998-1999, densities of oligochaetes have progressively increased in shallower and mid-depth regions likely due to the increased amount of food resulting from the biodeposition of organic material by Dreissena. (2015-2018)
Lake Erie and Michigan Benthos Final Report (PDF, 3MB)
We collected and analyzed samples at different trophic levels to determine the prevalence of contaminants in the Niagara River’s fish and wildlife, in particular those that contain halogenated compounds with a tendency to bioaccumulate. These contaminants are analyzed in water collected near wastewater treatment plants’ outflow into the river, and in predatory fish and avian and mammal wildlife. In particular, we are focusing on pharmaceuticals that enter the river routinely and may affect animal behavior. Our focus will include one of the most commonly prescribed antidepressants, selective serotonin reuptake inhibitors (SSRIs), which may cause impairments in fish and wildlife. (2015-2018)
News article: In the News: Alicia Pérez-Fuentetaja
During the last 50 years the ecosystem of Lake Erie has experienced major environmental changes, from anthropogenic eutrophication in 1930-1960s, to nutrient and pollution abatement in the 1970s, and then the introduction of exotic dreissenids in the 1980s. Currently, the lake-wide benthic community is dominated by dreissenids. The number of exotic species increases every decade, and their impact has had enormous consequences for the whole ecosystem. In the summer of 2014, within the project “Lake Erie & Lake Michigan Benthos: Cooperative Science & Monitoring Initiative,” we conducted a lake-wide survey of the benthic community using traditional (PONAR grabs, SCUBA) and modern (underwater video) methods, and we are currently working on data analysis. Data from this wide-lake survey will be compared to historical data to assess changes in the benthic community and trends in dreissenid populations that have important management implications.
We are using data collected during the last two decades of Great Lakes benthic monitoring conducted by the U.S. EPA’s Great Lakes National Program Office to describe the spatial and temporal patterns of benthic communities, assess their status, trends, and main drivers, and to infer the potential impact of these community changes on ecosystem functioning. Analysis of temporal trends revealed that the largest changes occurred in profundal communities, apparent in significant shifts in dominant taxa across all lakes except Lake Superior. In lakes Michigan, Huron, and Ontario, the former dominant Diporeia was replaced with Dreissena and Oligochaeta. Profundal species, with the exception of dreissenids, became less abundant, and their depth distribution has shifted. In contrast, density and diversity of native littoral and sublittoral communities increased. The invasion of dreissenids was among the most important drivers of changes in benthic communities. Continued monitoring is critical for tracking unprecedented changes occurring in the Great Lakes ecosystem. (2013-2018)
Burlakova et al., 2018. The benthic community of the Laurentian Great Lakes: analysis of spatial gradients and temporal trends from 1998 to 2014. Journal of the Great Lakes Research. In print. DOI 10.1016/j.jglr.2018.04.008. Open Access.
Great Lakes Center researchers were awarded a grant for $835,829 by the Niagara Greenway Ecological Fund to investigate lake sturgeon habitat use, feeding ecology and benthic resource availability in the Lower Niagara River for 2014-2018 (principal investigators Alexander Karatayev, Lyubov Burlakova from Buffalo State, and Dimitry Gorsky from USFWS).
The lower Niagara River provides habitat to one of the few remnant populations of lake sturgeon (Acipenser fulvescens) in the lower Great Lakes. Evidence shows that this population may be in recovery (Buffalo News), but information about sturgeon ecology in this unique system is lacking. In this project, we studied the diversity, distribution and density of benthic forage resources and the biology and ecology of lake sturgeon in the lower Niagara River. We also determined lake sturgeon movement patterns, habitat use, and diet and related it to our benthic habitat analysis to determine substrate and habitat preferences and to predict a carrying capacity for lake sturgeon in the lower Niagara River. To date, we collected over 250 benthic samples and produced a habitat map which will be the basis for future habitat restoration projects in the river. Our study produced an assessment of food availability and habitat preferences of lake sturgeon in relation to restoration of the local population to aid researchers and managers in developing measures to protect and enhance habitat to advance lake sturgeon recovery in the lower Niagara River.
An interesting finding of this study was that two non-native species dominated the diet of lake sturgeon: the amphipod Echinogammarus ischnus and the round goby (Neogobius melanostomus). Stable isotopes revealed that round goby was the primary contributor to the long-term (i.e., fin) average diet whereas short-term (i.e. blood) diet was more diverse. In contrast to findings from other systems, adult lake sturgeon in the lower Niagara River were primarily piscivorous, actively targeting live fish prey. The recovery of this population is potentially supported by high availability of energetically-rich, but non-native food resources. This work has resulted in three publications and numerous talks presented at national and international meetings. (2013-2018)
Starting in 2008, the Great Lakes Center monitored two sites in eastern Lake Erie for the Lower Trophic Level Assessment, a multiagency effort begun in 1999 by the Forage Task Group of the Great Lakes Fisheries Commission. This long-term project coordinates the efforts of state and federal agencies at sampling stations throughout Lake Erie to build a database of biotic and abiotic information and describe annual trophic conditions. From May through October we collect physical limnology data, water samples, and plankton samples biweekly, and take benthic samples three times a year. Because of human resource limitations, 2018 was our last field season for the Long-term monitoring of Lake Erie.
A poster from this project was presented at the 13th Annual Faculty/Staff Research and Creativity Fall Forum in Fall 2012. (2008-2018)
Almost every study of Dreissena in the Great Lakes has relied on bottom grabs to characterize mussel presence and biomass, but until now, the scale at which mussel cover varies has largely been unknown. In 2015, in collaboration with the U.S. EPA, University of Michigan, and NOAA, we collected 421 PONAR grab samples from 143 sites, and 429 underwater video images to estimate the spatial distribution of quagga mussels in Lake Michigan. We developed a novel method, which analyses video footage recorded from a GoPro camera on a towed benthic sled, to estimate dreissenid cover and biomass. We compared quagga mussel cover and biomass estimates based on 3 replicate PONARs versus 500-meter-long video transects.
Overall, replicate PONAR samples yielded very high errors in estimates of quagga mussel presence, especially at sites with low to moderate mussel cover, because mussel cover heterogeneity typically occurs at spatial scales much larger than the sample size collected by replicate bottom grabs (0.052 m2). As a result, this method offers a straightforward, inexpensive method to drastically reduce uncertainty in lake-wide estimates of Dreissena presence, especially in regular monitoring surveys which study a small (<50) number of sites.
We hypothesize that, in the shallow littoral zone, quagga mussels have an abundant food supply but are limited by wave activity and therefore will form large aggregations on hard substrates, but almost no mussels will be found on soft and unconsolidated sediments, resulting in high heterogeneity in their distribution. In contrast, in the deep stable profundal zone with no wave action, mussels are food limited and will form small loose aggregations, which maximizes food consumption and results in low heterogeneity in distribution. The largest Dreissena density will therefore be observed in the intermediate depth zone, where sediment deposition is highest and wave activity does not reach the bottom. Based on these data we have made 8 presentations at various meetings and conferences and submitted a manuscript for publication in the Journal of the Great Lakes Research. (2015-2017)
Lake Erie has the longest history of colonization by both Dreissena polymorpha and D. rostriformis bugensis in North America and is therefore optimal for the study of long-term dynamics of dreissenid species. Distribution of dreissenid species in Lake Erie varied depending on the time since the initial invasion, depth, and lake basin. During 2014, quagga mussels were found at various depths and in all basins, while zebra mussels were common in the western basin only and were limited in the central and eastern basins to a very few spots in shallow depths, resulting in almost complete replacement of D. polymorpha with D. r. bugensis. We found that a deep, offshore hypoxic zone restricts Dreissena population to shallow areas of the central basin. Deeper than 20 m, where bottom hypoxia routinely develops, only a small number of young of the year mussels were found, indicating restricted survival of >1 year old mussels. In the western basin of Lake Erie, with occasional episodes of severe oxygen depletion, all mussels were < 3 years old, suggesting die-offs once every 2-3 years. We suggest that monitoring of Dreissena occurrence and length-frequency distribution can be a cheap and effective tool in mapping of the extent and frequency of hypoxia in freshwater.
In the Laurentian Great Lakes, the most severe hypoxia routinely develops in the central basin of Lake Erie, causing strong negative ecological impacts. In collaboration with scientists from University of Michigan, Purdue University, U.S. EPA, and USGS, we measured bottom dissolved oxygen using 19 high frequency data loggers distributed throughout the central basin to validate a three-dimensional hydrodynamic-ecological model simulating dissolved oxygen distribution, and compared predicted values with the distribution of Dreissena. We found that a deep, offshore hypoxic zone was formed by early August, and expanded into nearshore waters by late September, restricting Dreissena population to shallow areas of the central basin. Deeper than 20 m, where bottom hypoxia routinely develops, only young of the year mussels were found in small numbers, indicating restricted recruitment and survival of young Dreissena. Monitoring Dreissena occurrence and length-frequency distribution can be an effective tool for mapping the extent and frequency of hypoxia in freshwater. In addition, our results suggest that an anticipated decrease in the spatial extent of hypoxia resulting from nutrient management has the potential to increase the spatial extent of profundal habitat in the central basin available for Dreissena expansion. Based on these data we have made 4 presentations at various meetings and conferences and submitted a manuscript for publication in the Journal of the Great Lakes Research. (2014-2017)
This project compared fish and macroinvertebrate communities in Elton Creek before and after an in-stream and riparian zone restoration project. The original restoration work was intended to improve trout habitat along a 1 km reach. We sampled fish and invertebrates several months prior to the project onset, and six- and 12-months post-project. Sculpins did not respond to the restoration, but trout numbers in the restoration section improved slightly. Macroinvertebrate community response was also assessed. (2014-2016)
The round goby (Neogobius melanostomus) has been implicated in the alteration of both macroinvertebrate and fish communities in tributary streams to the Great Lakes. Initial work in this project assessed whether an invasive invertivorous, benthic fish-mediated trophic cascade (fish predator to insect shredders/grazers to microbial communities to leaf breakdown) influences microbial community structure. This was the first application of community respiration profiling to assess a possible cascade effect on microbes in a stream ecosystem.
Later work in this project assessed whether the round goby impacted crayfish foraging, leading to a change in leaf litter decomposition. We used a field mesocosm manipulation to assess whether round gobies or crayfish had different impacts on the benthic macroinvertebrate community and then, indirectly, on leaf mass loss. (2011-2016)
The Texas Hornshell (Popenaias popeii) is listed as a Species of Greatest Conservation Need in Texas and New Mexico, as Endangered in both states, and is a candidate for listing in both states under the federal Endangered Species Act. Using an opportunity provided by the U.S. Fish and Wildlife Service for bilateral species conservation effort in New Mexico and Texas, we assessed the current distribution and habitat requirements of P. popeii in Texas, evaluating existing populations and their trends, and studying the species’s biology to develop the recovery plan and management options for P. popeii in Texas. In 2011-2014, we studied the current distribution and population densities in the Devils River and the Rio Grande River near Laredo using mark-recapture methods. We found the largest known population of P. popeii between Laredo and Eagle Pass, which is healthy and reproducing. However, probably due to pollution, the species has not been found downstream from Laredo. We analyzed all historical data and documented long-term changes in the distribution of P. popeii in Texas including range fragmentation and local extirpations to evaluate changes in the population’s size and distribution range over the last 100 years. Sampling over 250 sites in four rivers, constituting the entire historical range of P. popeii in Texas, we found that the species has been extirpated from two rivers, a 75% decrease in the combined total length of the rivers populated by the mussel, and an 72% overall decline in the population size of P. popeii. The results of this project are published in two papers and presented at national and international scientific meetings, and were recently used by U.S. FWS for Species Status Assessment under the Endangered Species Act. (2011-2016)
News article: 2012 update
Lake Erie has the longest history of colonization by both Dreissena polymorpha and D. rostriformis bugensis in North America and is therefore optimal for the study of long-term dynamics of dreissenid species. Distribution of dreissenid species in Lake Erie varied depending on the time since the initial invasion, depth, and lake basin. During 2009-2012, quagga mussels were found at all depths and in all basins, while zebra mussels were common in the western basin only, and in the central and eastern basins were limited to shallow depths, resulting in an almost complete replacement of D. polymorpha with D. r. bugensis in the deep parts of the lake. In the shallow western basin of Lake Erie, zebra mussels represented >30% of the combined dreissenid density even after more than 20 years of coexistence. We found a sharp and significant decline in quagga mussel density and biomass in 2009-2012 that could be explained by Dreissena density-dependent processes, predation, or by a geographical sampling bias. Patterson et al. (2005) sampled the northern littoral zone of the eastern basin with extensive limestone outcroppings and high Dreissena density, while in 2009-2012 we sampled the southern littoral zone dominated by sand with low Dreissena density. In summer of 2014, we are going to collect over 300 Dreissena samples to determine the current status of zebra and quagga mussel populations in Lake Erie.
During 2014, quagga mussels were found at various depths and in all basins, while zebra mussels were common in the western basin only and were limited in the central and eastern basins to a very few spots in shallow depths, resulting in almost complete replacement of D. polymorpha with D. r. bugensis. In the shallowest western basin of Lake Erie, zebra mussels distributed as widely as quagga mussels, but represented <15% of the combined dreissenids density and wet biomass. In addition, to further elucidate the relationship between hypoxia and dreissenid abundance, an exploratory dreissenid abundance/habitat mapping approach was conducted with both underwater cameras mounted on a Ponar grab and on a benthic sled towed by U.S. EPA Great Lakes National Program Office R/V Lake Guardian. Preliminary video footage analysis verified by Ponar grab samples revealed that Dreissena spp. avoid the central basin hypoxic zone and that monitoring dreissenid distribution and size structure can be an effective tool in mapping of the extent and frequency of hypoxia in a large waterbody. (2013-2015)
Since the introduction of dreissenid mussels into the Laurentian Great Lakes in the late 1980s, the diverse native mussel communities of the region have declined sharply. However, there have been several locales identified as refuges in coastal and nearshore areas. Although these have existed with the ongoing threat of dreissenid mussels in nearby offshore waters for over 20 years, the long-term survival of unionids in these habitats remains in question.
During this large collaborative project funded by the U.S. Fish and Wildlife Service, we surveyed over a total of 198 sites at 88 locations in bays, coastal wetlands, and drowned river mouths in the lower Great Lakes region and collected 4,329 individual unionids of 26 species. This information will help managers develop conservation strategies to sustain existing populations in these refuges. This expansive project also trained multiple undergraduate and graduate students, creating a cadre of future scientists and managers who will work to protect this imperiled resource, including graduate student Isabel Hannes (University at Buffalo) studying the phylogenetic relationship between Lampsilis radiata and L. siliquoidea, the levels of intermixing, and gene flow at different spatial scales. While species assemblages in the lakes have shown major shifts, these findings are especially encouraging given that surveys shortly after the dreissenid invasion pointed toward total extirpation of the unionid fauna. The number and weight of dreissenids attached to unionid shells was found to be tenfold fewer than in the early stages of invasion, indicating that the adverse impact of dreissenids on unionids has declined. We also found that the rate of infestation depends on the dominant Dreissena species in the lake: zebra mussels infested unionids much more often and in greater numbers. Consequently, the proportion of infested unionids, as well as the number and weight of attached dreissenids were lower in waterbodies dominated by quagga mussels. This was the first large-scale systematic study that revealed how minor differences between two taxonomically and functionally related invaders may have large consequences for native communities they invade (Burlakova et al. 2014). Results of the study were published in seven papers and presented at multiple meetings in the US and abroad. Great Lakes Unionid Refuge Project (2010-2015)
Most of the invasive species discovered in the Great Lakes since 1994 are native to the Ponto-Caspian region, including species that have had strong negative impacts in the Great Lakes (for example, dreissenid mussels and the round goby). The rich biota of the Ponto-Caspian region coupled with a high volume of commercial shipping traffic strongly suggests that this region will continue to be a major source of invasive species to the Great Lakes. We worked on two projects to assess invasion risk in Ponto-Caspian fishes that had not been included in previous studies, “Evaluating Ponto-Caspian Fishes for Risk of Great Lakes Invasion” from 2010–2011 and “Enhanced Early Detection of Invasive Ponto-Caspian Fishes in the Great Lakes” from 2012–2014.
In the first study, we developed biological profiles and a complete listing of high-risk invasive fishes from the Ponto-Caspian region and evaluated the likelihood that current ballast water regulations would prevent invasion of the Great Lakes by these high-risk species based on physiological and ecological data. We reviewed English-language publications and untranslated European literature (published primarily in Russian) to analyze invasion risk for over 40 Ponto-Caspian fishes for which data had previously been incomplete or unavailable. We identified four new species of Ponto-Caspian fishes as having a high risk of invading, spreading, and causing significant harm in the Great Lakes. Those four species are the black-striped pipefish (Syngnathus abaster), Caspian tyulka (Clupeonella caspia), Volga dwarf goby (Hyrcanogobius bergi), and Caspian bighead goby (Ponticola gorlap). Our analysis indicated that current regulations regarding ballast water exchange are likely to be effective in preventing introductions of high-risk Ponto-Caspian fishes based on salinity tolerances and dilution effects. However, more information was needed on larval and egg densities in European ports to fully predict efficiencies of ballast water exchange.
In the second project, we studied the geographic distributions, habitat use, and reproductive biology of high-risk Ponto-Caspian fishes identified in our earlier project and the work of others (e.g. Kolar and Lodge 2002), focusing on areas in and around key European ports. We then used discriminant analysis to identify fishes that had a high probability of becoming established, spreading, and having significant negative impacts in the Great Lakes. Our updated listing of high-risk Ponto-Caspian fishes includes five species identified previously (the Black and Caspian Sea sprat, Eurasian minnow, big-scale sand smelt, European perch, and monkey goby) and five additional species (the Black sea shad, Caspian tyulka, Volga dwarf goby, Caspian bighead goby, and black-striped pipefish). Of these ten species, four (the monkey goby, big-scale sand smelt, Caspian tyulka, and black-striped pipefish) are likely to survive ballast water exchange as eggs, larvae, or adults based on salinity tolerances. We used a variety of sources of information (primarily European literature available in English and Russian) to more accurately assess fine-scale geographic distributions and “propagule pressure” in European shipping ports associated with high-risk Ponto-Caspian fishes to identify spatial and seasonal “hot spots” in and around Great Lakes ports that should be the focus of future surveillance and early detection efforts. The results of the project will improve our estimates of invasion risk by examining not only species characteristics, but also the likelihood of successful introductions based on current geographical distributions and seasonal variation in occurrences in Europe. As a part of the project, we also integrated species identification information and other outreach products in development from our previous GLRI project that target fisheries managers, recreational water users and coastal educators, and made this information easily available. (2010–2015)
News article: Spring 2013 Newsletter (PDF, 2MB)
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