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Peter C. Esselman

Publications and source records attributed to Peter C. Esselman.

At least 37 records · Page 2Linked to original sources

Paired comparisons with quiet surface drones show evidence of fish behavioral response to motorized vessels during acoustic surveys in Lake Superior

Acoustic surveys are important for fish stock assessments, but fish responses to survey vessels can bias acoustic estimates. We leveraged quiet uncrewed surface vessels (USVs) to characterize potential bias in acoustic surveys. Five conventional motorized ships overtook USVs from astern over 2 km transects at night in Lake Superior in 2022. We examined the difference in acoustic backscatter, average target depth, and average target strength (TS) between USV and motorized vessels. Although sound level measurements from the motorized vessels sometimes exceeded recommendations for scientific vessels, we did not detect differences in acoustic measures among survey vessels. However, the USVs recorded 2 dB higher acoustic backscatter and TS than motorized vessels, leading to ~15% higher fish densities with drones when using in situ TS and echo integration. Differences in fish density would increase to 30-60% if a standard TS value was applied. Target depth did not differ between USVs and motorized ships. These results are consistent with a change in orientation but not depth of insonified fish and limited horizontal avoidance of motorized survey vessels.

Lake Superior↗

Status and trends of the Lake Huron prey fish community, 1976-2023

The U. S. Geological Survey-Great Lakes Science Center has monitored annual changes in the offshore (depth >9m) prey fish community of Lake Huron since 1973. Monitoring of prey fish populations in Lake Huron is based on a bottom trawl survey that targets demersal (benthic) species and an acoustic-midwater trawl survey that targets pelagic species and life stages. In 2023, Bloater ( Coregonus hoyi ) accounted for 77% of the main basin biomass in bottom trawls and 86% of the main basin biomass in the acoustics survey. Despite this sustained importance of native species in the main basin, species diversity is below desired levels. Bloater in the main basin has exhibited population growth and strong recruitment in recent years, and Cisco ( Coregonus artedi ) has exhibited increased biomass in the North Channel since 2015. In contrast non-native Alewife ( Alosa pseudoharengus ), whose population collapsed in 2004 and has not recovered, were less than 1% of fish biomass in 2023. Rainbow Smelt ( Osmerus mordax ) accounted for 7% of the main basin biomass in bottom trawls and 22% of the main basin biomass in the acoustics survey. Despite remaining the second-most abundant prey species in the main basin, Rainbow Smelt has not shown appreciable increases in biomass despite recent strong year classes. Deepwater Sculpin ( Myoxocephalus thompsonii ) increased by 47% in 2023 and were 33% of the long-term average. Slimy Sculpin ( Cottus cognatus ) increased to 60% of the long-term average but remained rare in bottom trawl catches. In contrast, biomass of Round Goby ( Neogobius melanostomus ), a non-native species similar ecologically to the sculpin species, remained near the record high biomass reached in 2022. Current lake conditions characterized by ongoing oligotrophication seem to favor native coregonines over non-native fishes. Use of complementary surveys (bottom trawl, acoustics) remains important for evaluating prey fish status in Lake Huron, where prey fish community dynamics vary by basin and prey fish responses to changing environmental conditions depend on species and/or habitat.

Lake Huron↗

Using multiscale environmental and spatial analyses to understand natural and anthropogenic influence on fish communities in four Canadian rivers

Science-based conservation of riverine fishes can be best targeted with specific information about spatial-ecological controls on the community, including anthropogenic stressors. Because anthropogenic stressors can originate at multiple spatial scales, we investigated the influence of natural and anthropogenic variables summarized within the reach, valley, and catchment on fish community composition along four river mainstems in Ontario, Canada. We used Redundancy Analyses (RDA) to explore models with multi- and single-scale variables on fish community composition. We used partial RDAs to differentiate the relative effects of variable types in multiscale models and to determine if spatial variables explained additional variation in fish community composition. Catchment variables accounted for the majority of explained variation in fish community composition in three of the four rivers, but instream habitat variables accounted for considerable variability in fish community composition in the two rivers that are highly fragmented by dams or naturally occurring rapids. Natural and human-derived fragmentation in rivers may reduce the influence of catchment controls, disrupt longitudinal gradients, and increase the influence of local instream habitat. Environmental variables that explained fish distribution had longitudinal or patchy spatial pattern within rivers, but spatial variables representing impediments to fish dispersal and proximity to receiving waterbodies failed to explain additional variation in fish community composition.

Ontario↗

Large-scale variation in lakebed properties interpreted from single-beam sonar in two Laurentian Great Lakes

Acoustic seabed classification (ASC) is an important method for understanding landscape-level physical and biological patterns in the aquatic environment. Bottom habitats in the Laurentian Great Lakes are poorly mapped to date, and will require a variety of contributors and data sources to complete. We repurposed a long-term split-beam echosounder dataset gathered for purposes of fisheries assessment to estimate lakebed properties utilizing unsupervised classification of echo return data. We interpreted first echo properties representing lakebed hardness and roughness to define and map three statistically supported lakebed classes revealed through cluster analysis. Our results indicate coherent and logical class boundaries and suggest that the dataset has promise for expanded use in ASC. To improve inferences using repeated measures, future work should focus on collecting ground truth information for areas previously surveyed and on collecting concurrent ground truth information when sampling acoustic data moving forward.

Michigan, Ontario, Wisconsin↗

Model-based assessment and mapping of total phosphorus enrichment in rivers with sparse reference data

Water nutrient management efforts are frequently coordinated across thousands of water bodies, leading to a need for spatially extensive information to facilitate decision making. Here we explore potential applications of a machine learning model of river low-flow total phosphorus (TP) concentrations to support landscape nutrient management. The model was trained, validated, and then applied for all rivers of Michigan, USA to identify potential drivers of nutrient variation, predict alteration in nutrient concentrations from minimally disturbed conditions, and explore reach specific sensitivity to riparian agricultural change. A boosted regression tree model of low-flow TP concentrations trained on natural and anthropogenic landscape predictors accounted for 53 % of variation in cross-validation data, had good accuracy, little bias, and plausible relationships between predictors and response. Percent riparian agricultural cover accounted for the greatest root mean square error reduction in the modeled response (33.2 %), followed by riparian soil permeability (12.9 %), watershed slope (9.6 %), and percent urban cover (9.6 %). An apparent non-linear relationship between TP concentrations and percent riparian agricultural cover suggested steep positive increases in stream TP concentrations between 10 and 30 % upstream riparian agricultural cover. Predicted minimally disturbed TP concentrations were spatially variable and ranged from 7.0 to 48.5 μg l −1 , with the highest concentrations in watersheds draining low-permeability lake plain soils. Comparison of minimally disturbed predictions to those from the early 2000s suggested that much of northern Michigan existed close to the reference condition, while lower Michigan streams were often substantially enriched. Our predicted values of minimally disturbed condition generally agree with previous studies but offer greater geographic specificity. Expanded application of machine learning modeling with landscape predictor data have great potential to inform large scale strategy development in landscapes with sparse reference data.

Michigan↗

Status and trends of the Lake Huron prey fish community, 1976-2021

The U.S. Geological Survey Great Lakes Science Center has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October of each year and an acoustics-midwater trawl survey, which began in 2004 and is conducted in September-October. Due to weather delays and continued travel restrictions during 2021, there were no bottom trawl samples off the port of Goderich, Ontario and two acoustic transects were cancelled in Georgian Bay. Prey fish biomass in Lake Huron in 2021 was dominated by two species, Bloater (Coregonus hoyi) and Rainbow Smelt (Osmerus mordax). In the main basin, prey fish biomass remained below levels observed prior to community-wide declines that began in the early to mid 1990s. Bloater was the most abundant prey fish species in the main basin, whereas Rainbow Smelt was the most abundant prey species in the North Channel and in Georgian Bay. Both surveys suggested that Bloater biomass is increasing in the main basin. Low biomass of invasive species like Alewife (Alosa pseudoharengus) and Rainbow Smelt is consistent with fish community objectives focused on restoration of native fish communities. Abundance of invasive Round Goby (Neogobius melanostomus) increased in 2021 relative to 2019-2020. Biomass of the native Cisco (Coregonus artedi) increased in the North Channel in 2021 but remained low in Georgian Bay, possibly as an artifact of reduced sampling. Biomass of Slimy Sculpin (Cottus cognatus) and Deepwater Sculpin (Myoxocephalus thompsoni) in 2021 remained low but within the range observed over the past decade. Reduced lake productivity, predation by a recovering piscivore community, and shifts in food web dynamics that favor fish production in nearshore environments may prevent prey fish biomass in offshore areas from returning to levels observed prior to the early 1990s. However, increased biomass of Bloater and Cisco suggests that lake conditions may favor recovery of native corgonines.

Lake Huron↗

Status and trends of the Lake Huron prey fish community, 1976-2022

The United States Geological Survey-Great Lakes Science Center has monitored annual changes in the offshore prey fish community of Lake Huron since 1973. Monitoring of prey fish populations in Lake Huron is based on a bottom trawl survey that targets demersal (benthic) species and an acoustic-midwater trawl survey that targets pelagic species and life stages. Status of the main basin prey fish community in 2022 was considered ‘Fair’ due to sustained improvements in native species status but species diversity that remains below desired levels. Current lake conditions, characterized by ongoing oligotrophication, seem to favor native coregonines like Bloater ( Coregonus artedi ), which in the main basin has exhibited signs of population growth and strong recruitment in recent years, and Cisco ( Coregonus artedi ), whose biomass in the North Channel increased for the second consecutive year in 2022. In contrast, conditions in the main basin are less favorable for exotic prey fish such as Alewife ( Alosa pseudoharengus ), whose population collapsed in 2014 and has not recovered, and Rainbow Smelt ( Osmerus mordax ), which remains the second-most abundant prey species in the main basin but has produced multiple weak year classes over the past decade including in 2022. Status of benthic prey fish in the main basin in 2022 depended on species. As in prior years, the native sculpin community in 2022 consisted primarily of Deepwater Sculpin ( Myoxocephalus thompsoni ) because Slimy Sculpin ( Cottus cognatus ) has become exceedingly rare. In contrast, biomass of the ecologically similar Round Goby ( Neogobius melanostomus ), an exotic species, reached an all-time high in 2022. Use of complementary surveys (bottom trawl, acoustics) remains important for evaluating prey fish status in Lake Huron, where prey fish community dynamics vary by basin and prey fish responses to changing environmental conditions depend on species and/or habitat.

Lake Huron↗

Gap analysis: A proposed methodology to describe and map historical and contemporary populations and habitats

This is a methodology paper that describes an approach for modeling and mapping historical and contemporary spawning areas for coregonine fishes in the Laurentian Great Lakes. Coregonines are a family of native whitefishes and ciscoes that are now greatly reduced or extirpated, but once served important roles for both the food web and society. This method can illustrate where habitats once existed and where they are today - critical information for restoration and conservation actions.

Great Lakes↗

Great Lakes spatial priorities study

Spatial data about the bathymetry, habitat characteristics, underlying geology, and other features of the ocean and inland seas are essential for decision-making. Marine research and management organizations use these data to help ensure safe navigation, promote sustainable fisheries, extract energy, and protect marine habitats in the coastal and ocean waters of the U.S. Exclusive Economic Zone (EEZ) and Laurentian Great Lakes. Many of these organizations may have overlapping or shared mapping interests without knowing it. In a multi-jurisdictional planning environment, it can be challenging and cumbersome to determine where other entities have shared or overlapping mapping interests, especially across a transnational region such as the Great Lakes. State and provincial governments, federal governments, academia, tribes and First Nations, and other stakeholders from both the U.S. and Canada all have mapping interests across Great Lakes waters. Identifying and communicating target geographies for new data collection that are shared among multiple organizations can both help to avoid redundancy of new mapping efforts, and create opportunities for greater efficiency through collaboration. To address this issue, a spatial priorities study was conducted using a geospatial tool developed by the National Ocean Services National Centers for Coastal and Ocean Science (NCCOS). The tool provided an easy-to-use online interface in which programs can identify their priorities in a simple and straightforward way. This study asked representatives of Great Lakes management and science organizations to identify the areas for which they needed maps of lakebed features on a near-term, mid-term, and long-term timeframe, and why. Then, the responses were analyzed and overlaid to determine areas of shared mapping need and opportunity and to determine the types of map products needed. The analysis revealed high interest among multiple organizations in discrete geographies including the Minnesota and Wisconsin shoreline from Duluth to the eastern extent of the Bayfield Peninsula, Green Bay in Lake Michigan, and the southern coastlines of Lake Erie and Lake Ontario, the St. Marys River, and the northern Lake Superior coastal waters near Grand Portage, MN. Lower priority mapping interest were distributed widely across all lakes, but tended to be concentrated in nearshore areas (<30 m depth). The analysis also indicated that the top mapping justifications were Habitat/biota/natural area, Benthic exploration, Commercial and recreational fishing, and Scientific research. The top desired map product types were Elevation, Substrate/sub-bottom geologic characterization, and Habitat map/characterization, although participants on some lakes noted other less prevalent product types. Following from previously conducted NOAA and non-NOAA Federal spatial prioritization exercises, the results of this regional focus can help mapping organizations better understand how their priorities align with the needs of regional organizations, allow for more efficient coordination and funding, and enable partners to leverage assets and resources to fill their most pressing data and information gaps across Great Lakes waters. The U.S. Mapping Coordination Site hosts the results of this study and other spatial prioritization studies. Through this website, one can interact with the study results along with recent and planned mapping efforts. NOAA intends to update their spatial priorities on a three- to five-year basis. Future studies should strive to expand participation of federal agencies, state and local governments, federally-recognized tribes, academia, and private industry (among other stakeholders) to seek out ocean mapping partnerships in conjunction with the National Ocean Mapping, Exploration and Characterization (NOMEC) goals map once, use many times.”

Great Lakes↗

Status and trends of the Lake Huron prey fish community, 1976-2019

The USGS Great Lakes Science Center has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October of each year and an acoustics-midwater trawl survey, which began in 2004 and is conducted in September-October. Both surveys were completed in their entirety in 2019. Prey fish biomass in Lake Huron in 2019 was dominated by two species, Bloater ( Coregonus hoyi ) and Rainbow Smelt ( Osmerus mordax ). In the main basin, prey fish biomass remained below levels observed prior to community-wide declines that began in the early to mid 1990s. Bloater was the most abundant prey fish species in the main basin, whereas Rainbow Smelt was the most abundant prey species in the North Channel and in Georgian Bay. Both surveys suggested that Bloater biomass is increasing in the main basin. Low biomass of invasive species like Alewife ( Alosa pseudoharengus ) and Rainbow Smelt is consistent with fish community objectives focused on restoration of native fish communities. Abundance of invasive Round Goby (Neogobius melanostomus) in 2019 was low relative to 2018. Biomass of the native Cisco ( Coregonus artedi ) continued to increase in the North Channel and Georgian Bay. Biomass of slimy sculpin ( Cottus cognatus ) and Deepwater Sculpin ( Myoxocephalus thompsoni ) in 2019 was down from 2018 but within the range observed over the past decade. Reduced lake productivity, predation by a recovering piscivore community, and shifts in food web dynamics that favor fish production in nearshore environments may prevent prey fish biomass in offshore areas from returning to levels observed prior to the early 1990’s. However, increased biomass of Bloater and Cisco suggests that lake conditions may favor recovery of native coregonids.

Lake Huron↗

Status and trends of the Lake Huron prey fish community, 1976-2020

The USGS Great Lakes Science Center (GLSC) has assessed annual changes in the offshore prey fish community of Lake Huron since 1973. Assessments are based on a bottom trawl survey conducted in October and an acoustics-midwater trawl survey conducted in September-October. In 2020, USGS-GLSC vessels were not permitted to cross into Canada due to the COVID-19 pandemic, so prey fish surveys sampled only sites in U.S. (Michigan) waters of Lake Huron. This prevented USGS from providing information about the current status and trends of prey fish communities in Georgian Bay and the North Channel. Prey fish biomass in U.S. waters of Lake Huron in 2020 remained below levels observed prior to community-wide declines that began in the early to mid-1990s. Fish community biomass was dominated by two species, Bloater (Coregonus hoyi) and Rainbow Smelt (Osmerus mordax). While both surveys found Bloater biomass in the main basin had declined from levels observed in 2019, Bloater still comprised over three-quarters of prey fish biomass in Lake Huron in 2020. Biomass and abundance for other prey fish species were within the range observed over the past five years. Current low biomass of invasive species like Alewife (Alosa pseudoharengus) and Rainbow Smelt is consistent with fish community objectives focused on restoration of native fish communities. Reduced lake productivity, predation by a recovering piscivore community, and shifts in food web dynamics that favor fish production in nearshore environments may prevent prey fish biomass in offshore areas from returning to levels observed prior to the early 1990’s. However, the dominance of Bloater in bottom trawl catches and acoustic surveys suggests that current lake conditions are conducive to the recovery of some native species.

Lake Huron↗

The species–area relationship for a highly fragmented temperate river system

Despite the importance of species–area relationships (SARs) to conservation, SARs in human‐fragmented rivers have received little attention. Our aim was to test for the presence and strength of SARs for littoral fish assemblages of an extensively dammed river in south‐central Ontario, Canada, and to examine long‐running hypotheses for the drivers of SARs. Twenty‐six navigational dams with locks built between 1837 and 1913 occur along the 160 km length of the Trent River examined in this study. We evaluated the relationship between richness and fragment area, and then used linear models to test whether the area per se, habitat diversity, or other hypotheses were best supported by the data. A power–function relationship with area explained 46% of the variation in fish species richness, and the slope ( z = 0.4) was high compared with SARs reported from other ecosystems, indicating that species accumulated rapidly with an increase in fragment area. Multi‐predictor models suggested that area was significantly related to richness, but that vegetation cover diversity had a stronger relative effect. The slope of our SAR may indicate that there is a high degree of isolation between populations in different fragments, even though the lock system reportedly allows some passage of organisms. Our findings also suggest that mitigating against local extinction due to small population sizes (i.e., area effects), and enhancing aquatic vegetation cover may be viable strategies for promoting species diversity in the study river. Studies of SARs in fragmented rivers may offer additional benefits to supporting restoration planning where efforts are being made to increase species diversity.

Ontario↗

Hydrogeomorphological controls on reach‐scale distributions of cichlid nest sites in a small neotropical river

The Cichlidae are among the most diversified families of fish in the Neotropics and represent an important component of aquatic biodiversity. Understanding cichlid nest‐site selection is important for assemblages facing uncertain futures due to species invasions and environmental change. This information could be used to predict how inter‐ and intraspecific competition for reproductive space may affect populations with changing community dynamics or to identify areas as targets for conservation. We investigated which hydrogeomorphological factors correlated to preferred nest sites of four native cichlid species in the Bladen River, Belize. We recorded the locations of nest sites and collected habitat data through the study reach, including flow velocity, depth, sediment type, fish cover type richness and distance to the bank. Nest locations and physical habitat data were used to construct spatially explicit habitat models using boosted regression trees (BRTs). The models provided statistically significant evidence that physical habitat variables influence the distribution of the nest sites. We found that all species except Archocentrus spilurus were associated with substrate, specifically sand. Thorichthys meeki was also associated with lower water velocities, whereas Cichlasoma salvini was influenced by all five variables. Vieja maculicauda and Archocentrus spilurus were both influenced by flow velocity, distance to bank and depth, although A. spilurus preferred deeper, slightly faster locations about the same distance to the bank. This study suggests that the spatial distribution of nest sites within this cichlid community is significantly different than random and is at least partially governed by physical controls.

Monkey River Basin↗

Outsized nutrient contributions from small tributaries to a Great Lake

Excessive nutrient inputs from tributary streams and rivers contribute to harmful algal blooms and coastal ecosystem degradation worldwide. However, the role that small tributaries play in coastal nutrient dynamics remains unknown because most monitoring and regulatory efforts focus only on the largest tributaries. We combined a 6-d sampling effort with discharge modeling to characterize nutrient inputs from nearly all watersheds draining to the world’s fifth largest lake. We found that streams are particularly likely to promote eutrophication in coastal ecosystems because they deliver water with higher concentrations of nutrients that are readily available to algae. Thus, our findings indicate that efforts to control nutrient loading could be enhanced by looking beyond the largest tributaries to include smaller streams.

Lake Michigan↗

A conceptual framework for the identification and characterization of lacustrine spawning habitats for native lake charr Salvelinus namaycush

Lake charr Salvelinus namaycush are endemic to the formerly glaciated regions of North America and spawn primarily in lakes, unlike most other Salmoninae. Spawning habitats for lake charr are thought to be characterized by relatively large substrate particle sizes which provide sufficient interstitial spaces for egg incubation, but little is known about the physical processes that create or maintain suitable habitats. We review the literature on lake charr spawning habitat and present a conceptual framework that examines the roles of physical variables in creating the appropriate conditions for egg incubation. A critical underlying assumption of this framework is that lake charr will select spawning habitats that provide suitable hypolentic flows for egg incubation. We suggest that the characterization of lakebed surface roughness, current patterns, substrate particle size, and groundwater flows at multiple spatial scales may yield significant insight into the physical mechanisms supporting lacustrine spawning habitats for lake charr and will be useful in creating predictive models of these habitats. This framework may also apply to other lake-spawning lithophilic fish species.

Environmental Biology of Fishes↗

Seasonal fluxes of dissolved nutrients in streams of catchments dominated by swidden agriculture in the Maya Forest of Belize, Central America

The biogeochemistry of nitrogen (N) and phosphorus (P) in tropical streams and rivers is strongly regulated by the pronounced seasonality of rainfall and associated changes in hydrology. Land use and land cover change (LULCC) can also be a dominant driver of changes in stream biogeochemistry yet responses are not fully understood and vary across different LULCC scenarios. We measured dissolved and total nitrogen (N) and phosphorus (P) concentrations in four tributary streams of the Temash River watershed in southern Belize, Central America. The dominant land use practice in each of the four study catchments was swidden agriculture. We documented a strong seasonal control on the export of nutrients from these study systems with daily N fluxes increasing approximately 10-fold during the onset of the rainy season. P fluxes increased almost 4-fold during the same time period. Comparisons with nutrient export coefficients from other tropical streams suggest that nutrient export in streams of the Temash River watershed is similar or slightly lower. Establishing improved understanding of the terrestrial and hydrologic controls of N and P transport across the terrestrial-aquatic boundary and developing a comprehensive nutrient budget that includes inputs and outputs associated with crop production is warranted in future work.

Water↗

Evidence for interactions among environmental stressors in the Laurentian Great Lakes

Co-occurrence of environmental stressors is ubiquitous in ecosystems, but cumulative effects are difficult to predict for effective indicator development. Individual stressors can amplify (synergies) or lessen (antagonisms) each other's impacts or have fully independent effects (additive). Here we use the Laurentian Great Lakes, where a multitude of stressors have been studied for decades, as a case study for considering insights from both a systematic literature review and an expert elicitation (or structured expert judgment) to identify stressor interactions. In our literature search for pairs of stressors and interaction-related keywords, relatively few studies (9%, or 6/65) supported additive interactions with independent stressor effects. Instead, both antagonisms (42%, or 27/65) and synergies (49%, or 32/65) were common. We found substantial evidence for interactions of invasive dreissenid mussels with nutrient loading and between pairs of invasive species (predominantly dreissenids × round goby), yet both sets of records included mixtures of synergies and antagonisms. Complete quantification of individual and joint effects of stressors was rare, but effect sizes for dreissenid mussels × nutrient loading supported an antagonism. Our expert elicitation included discussion in focus groups and a follow-up survey. This process highlighted the potential for synergies of nutrient loading with dreissenid mussels and climate change as seen from the literature review. The elicitation also identified additional potential interactions less explored in the literature, particularly synergies of nutrient loading with hypoxia and wetland loss. To stimulate future research, we built a conceptual model describing interactions among dreissenid mussels, climate change, and nutrient loading. Our case study illustrates the value of considering results from both elicitations and systematic reviews to overcome data limitations. The simultaneous occurrence of synergies and antagonisms in a single ecosystem underscores the challenge of predicting the cumulative effects of stressors to guide indicator development and other management and restoration decisions.

Ecological Indicators↗