Geology topics

Robin DeBruyne

Publications and source records attributed to Robin DeBruyne.

6 recordsLinked to original sources

USGS2022

Predicting physical and geomorphic habitat associated with historical lake whitefish and cisco spawning locations in Lakes Erie and Ontario

The Great Lakes basin was historically populated by multiple, coevolved coregonine species, but much of that diversity has been lost. In Lakes Erie and Ontario, both lake whitefish ( Coregonus clupeaformis ) and cisco ( Coregonus artedi ) occurred in high numbers before habitat degradation, overfishing, invasive species, and other factors caused significant declines. There is growing interest in restoring these populations, and suggested actions include restoration of critical habitats such as spawning habitat. Unfortunately, our current understanding of lake whitefish and cisco spawning habitat characteristics and locations in these lakes is limited. To highlight areas of potential importance for conservation and restoration, we used random forest models and data on historical spawning locations to predict lake whitefish and cisco spawning habitats based on hypothesized key factors including wind fetch, ice cover duration, distance from 1st and 6th order tributaries, and lake bottom substrate. Our model accurately predicted spawning habitat locations for 71% and 54% of cases for lake whitefish and cisco, respectively. Fetch was the most important variable in the lake whitefish model, with spawning habitats being most likely to occur in regions of low to moderate fetch. Cisco spawning habitats were most likely to occur in areas of relatively low fetch near a 1st order stream. We used these models to predict spawning habitat locations for both species across Lakes Erie, Ontario, and St. Clair. Our results improve our understanding of lake whitefish and cisco spawning habitat characteristics and will aid in the spatial prioritization of actions to restore these native fishes.

Lake Erie, Lake Ontario↗

USGS2021

A structured approach to remediation site assessment: Lessons from 15 years of fish spawning habitat creation in the St. Clair‐Detroit River system

Ideally, restoration re‐establishes natural processes in degraded habitats (e.g., flow and sediment regimes). However, in altered systems where process‐based restoration is not feasible, habitat construction is another approach to mitigate degradation. Because habitat construction does not directly focus on restoring processes that build and maintain desired habitats, projects must be developed and placed within the contemporary regulatory, ecological, and hydrogeomorphic context of a system, to maximize effectiveness. Here, we develop a framework for evaluating the regulatory, ecological, and hydrogeomorphic components using 15 years of fish spawning habitat construction in the St. Clair‐Detroit River System. The process began by identifying regulatory requirements at a coarse resolution to quickly focus on locations where ecological potential and hydrogeomorphic constraints could be assessed at finer resolutions. Next, ecological potential was assessed using a lithophilic fish spawning habitat suitability index. The suitability index identified five sites for habitat construction and Lake sturgeon spawning was documented at each site following construction. However, qualitative monitoring showed fine sediments accumulated at older sites. Thus, geomorphic assessments were incorporated to identify sediment sources and model flow within targeted areas. Since geomorphic assessments required the finest resolution and had the most uncertainty, they were conducted after broad‐scale regulatory considerations and ecological assessments narrowed focus to a few candidate sites. The order of operations identified in this case study evolved from the iterative approach of the restoration team, but in retrospect, it helped develop a framework that directed project development resources to aspects with more uncertainty, where learning is most critical.

Michigan, Ontario↗

USGS2021

Export of pelagic fish larvae from a large Great Lakes connecting channel

The St. Clair-Detroit River System is located in the heart of the North American Laurentian Great Lakes, connecting lakes Huron and Erie, contributing over 90% of the inflow to Lake Erie, and providing spawning habitat for many fishes including walleye (Sander vitreus), yellow perch (Perca flavescens), and lake whitefish (Coregonus clupeaformis). Dredging and channelization have greatly altered the Detroit River thereby reducing available spawning habitat and redirecting a majority of river discharge through deep canal-like channels to offshore areas of western Lake Erie at high velocities. Fish reproduction has been measured in the Detroit River using larval surveys for over 10 years. However, quantitative estimates of contributions from spawning in the system to Lake Erie fish populations have not been determined. We use long-term biological sampling and physical habitat surveys to characterize larval drift patterns and a Bayesian approach to quantify larval export from the Detroit River. Larval export from the Detroit River into Lake Erie varied by species, across years (2006–2015), and spatially among the multiple navigational channels in the lower Detroit River. Total annual export of walleye larvae ranged from 12 million in 2013 to 114 million in 2014, yellow perch larvae ranged from 319 million in 2014 to 690 million in 2013, and lake whitefish larvae ranged from 29 million in 2010 to 84 million in 2011. Given the widespread spawning, large numbers of larvae produced, and continued system-wide water quality and aquatic habitat improvements, the Detroit River provides valuable habitat and added resilience to Lake Erie fisheries despite suffering from severe anthropogenic disturbances.

Michigan, Ontario↗

USGS2021

Spatial extent of contemporary lake whitefish spawning in western Lake Erie

Degradation of lake whitefish (Coregonus clupeaformis) spawning areas in the Detroit River, Maumee Bay, and western Lake Erie reefs and shoals has been identified as a contributing factor to Lake Erie’s population collapse in the 1950s. This decline prompted the United States and Canada to take steps to improve the aquatic ecosystem of Lake Erie. A recent increase in commercial fish harvest and catch of early-life stages of lake whitefish in the western basin of Lake Erie provide evidence that lake whitefish are once again spawning in some of their historical spawning areas, however the extent of use is unknown. To investigate the contemporary distribution of lake whitefish spawning within western Lake Erie, 31 potential spawning locations were sampled for eggs in 2016 and 2017. A subset of sites within Maumee Bay and an open lake reef complex were sampled repeatedly each year to determine the onset of spawning and 17 sites outside these two areas were each sampled once to describe the spatial extent of spawning. Spawned eggs were first detected on 22 November in 2016 and on 18 November in 2017. Viable eggs were collected at 27 of 31 sampled locations, verifying that lake whitefish spawned in Maumee Bay, on the mid-lake reefs, and other locations in 2016 and 2017. These findings confirm that lake whitefish are using historical spawning areas and available spawning habitat in western Lake Erie. The extensive use of available spawning habitat adds spawning stock diversity that is vital for generating population stability and resilience.

Lake Erie↗

USGS2021

Contemporary and historic dynamics of lake whitefish (Coregonus clupeaformis) eggs, larvae, and juveniles suggest recruitment bottleneck during first growing season

To determine if a survival bottleneck occurs in Lake Erie's lake whitefish ( Coregonus clupeaformis ) population and explore possible mechanisms responsible, we examined contemporary and historical dynamics of lake whitefish eggs, larvae and juveniles. Widespread spawning and low overwinter egg retention were observed in 2016–2018, however subsequent larval CPUE remained consistent with historical observations when regular recruitment occurred. Highest larval CPUE was consistently observed in nearshore areas 3–11 km from mid-lake spawning locations. Fall age-1 juvenile presence was predicted by fall age-0 catches, indicating the bottleneck occurs during the first growing season. Our results suggest the following: (1) factors limiting recruitment affect survival during or after the pelagic larval stage to fall age-0, and (2) physical and biological processes underlying connectivity between spawning and nearshore nursery habitats may be limiting recruitment. Future research focusing on larval nursery habitat characterization and lake whitefish growth and survival may reveal mechanisms affecting recruitment.

Michigan, Ohio↗

USGS2020

Review of methods to repair and maintain lithophilic fish spawning habitat

Rocky reefs provide important spawning and refuge habitats for lithophilic spawning fishes. However, many reefs have been lost or severely degraded through anthropogenic effects like dredging, channelization, or sedimentation. Constructed reefs have been used to mitigate these effects in some systems, but these reefs are also subject to degradation which may warrant custodial maintenance. Monitoring and maintenance of natural or constructed spawning reefs are not common practices; therefore, few methodologies have been created to test the effectiveness of such tools. We conducted a literature review to assess available information on maintenance of rocky spawning habitats used by lithophilic fishes. We identified 54 rocky spawning habitat maintenance projects, most of which aimed to improve fish spawning habitats through the addition of spawning substrate ( n = 33) or cleaning of substrate ( n = 23). In comparison to shallow riverine studies focused on salmonids, we found little information on deep-water reefs, marine reefs, or other fish species. We discuss the possible application of potential spawning habitat cleaning methods from other disciplines (e.g., treasure hunting; archeology) that may provide effective means of reef maintenance that can be used by restoration practitioners.

Water↗