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Surveys Conducted on Lake Guardian (2019)

In 2019, the R/V Lake Guardian supported five Lake Erie CSMI surveys. This page presents summaries of the science and participating partners:

On this page:

Lower Food Web Surveys

Two lower food web CSMI surveys were conducted on Lake Erie using the R/V Lake Guardian in May and September 2019. These surveys addressed the Lake Erie Partnership’s Changing Food Web and In-lake Eutrophication science priorities.

The scientific objective of these surveys was to determine how water quality, hypoxia, and the pelagic lower food web vary spatially and seasonally in Lake Erie. As Lake Erie is a highly variable ecosystem, intensive surveys are required to understand the mechanisms controlling harmful algal blooms (HABs), hypoxia, and the lower food web.

Map of Sites sampled to monitor Lake Erie’s lower food webSites sampled to monitor Lake Erie’s lower food web.A total of 22 total stations were sampled during day and night over 3-4 days. The following samples were collected and analyzed at all sites or a subset of sites:

  • water quality nutrients
  • phytoplankton
  • zooplankton
  • larval fish
  • sediment

Samples were also collected to perform the following laboratory experiments:

  • primary productivity experiments
  • zooplankton nutrient excretion experiments

Photo of Research technician prepares an experiment to measure photosynthesis in Lake Erie Research technician prepares an experiment to measure photosynthesis in Lake Erie. Multiple technical instruments were deployed to measure the following optical parameters for validating water quality and HABs remote sensing models:

  • inherent optical properties
  • apparent optical properties

Numerous partners were involved on these surveys, including:

  • US EPA Great Lakes National Program Office
  • US EPA Office of Research and Development Mid-Continent Ecology Division
  • University of Michigan Cooperative Institute for Great Lakes Research
  • Michigan Technological Research Institute
  • The Ohio State University
  • University of Toledo
  • Cornell University

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Benthos Survey

Map of Sites sampled to monitor and map Lake Erie’s benthic organismsSites sampled to monitor and map Lake Erie’s benthic organisms.As part of the 2019 Cooperative Science and Monitoring Initiative (CSMI), teams of Great Lakes Restoration Initiative (GLRI) partners aboard the EPA research vessel Lake Guardian from July 15-23 monitored and mapped the distribution of bottom-dwelling organisms, known as benthos, to better understand the health of Lake Erie’s lower food web.
Benthic organisms are critical components of Lake Erie’s food web. They provide food for native fish such as yellow perch, white perch, burbot, white bass and lake whitefish in addition to non-native species including round goby, rainbow smelt and alewife. Benthic organisms include amphipods, which are small crustaceans, mollusks, annelid worms, and insect larvae.
Collecting data on the composition and health of the benthic community is essential to understanding how energy and nutrients are cycled throughout the lake, and whether changes to those cycles are occurring. Benthic organisms are also important indicators of ecosystem health, as many benthic species are sensitive to pollution.

Photo of marine technician collecting sediment from a Ponar samplerMarine technician collecting sediment from a Ponar sampler.

On the 2019 CSMI benthos survey, scientists collected underwater video footage and “grabbed” samples of the lake bottom sediment via a Ponar grab. Videos and samples allow the research team to estimate the presence and abundance of bottom-dwelling species, with a special emphasis on the distribution of invasive Quagga mussels. They compared 2019 data to results from past surveys to understand how the Lake Erie benthic community has changed over time and determine if Quagga mussel abundance, growth and health in Lake Erie are changing at different rates than in the other Great Lakes.

The teams conducting this research are made up of several GLRI partners:

  •     Environmental Protection Agency
  •     National Oceanic and Atmospheric Administration
  •     Buffalo State College
  •     Wright State University
  •     Cornell University
  •     Oak Ridge Institute for Science and Education
  •     Cooperative Institute for Great Lakes Research

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Lower Food Web Contaminants Survey

Photo of Preparing lists and labels for contaminant sampling Preparing lists and labels for contaminant sampling. In support of Lake Erie CSMI and the Great Lakes Fish Monitoring and Surveillance Program, researchers from Clarkson University, USGS, NOAA GLERL, SUNY-Fredonia, and SUNY-Oswego assessed the biomagnification of legacy contaminants and chemicals of emerging concern through the food chain at Western Basin and Eastern Bain sites in Lake Erie in June 2019. This survey sampled water, sediment, phytoplankton, zooplankton, and benthos for contaminant analyses, thus targeting the major components of the Lake Erie lower food web.

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Harmful Algal Blooms/Hypoxia Survey

The scientific objective of the survey is to examine how harmful algal blooms (HABS) and bottom hypoxia (lack of oxygen) are driving change in the structure, function and dynamics of Lake Erie’s food webs. The factors will be considered both separately and combined.

Map of General sampling plan to monitor Lake Erie’s food web in hypoxic, HAB, and hypoxic + HABs regions Targeted Lake Erie sampling zones for food web assessments in hypoxic areas, HAB areas, and areas where hypoxia and HABs overlapped

This research will examine how the presence of HABs and hypoxia can affect the quantity and quality of prey available to the ecosystem’s top predators (walleye and yellow perch). It will help us understand how toxins produced by HABs, such as microcystin, are distributed throughout the water column, as well as within the food web.

HABs/hypoxia cruises were conducted July and August 2019 using the RV Lake Explorer II (operated by the U.S. EPA Office of Research and Development) and the CCGS Limnos (operated by Environment and Climate Change Canada and Department of Fisheries and Oceans, Canada).

Photo of Launching the rosette water sampler at night in Lake Erie Launching the rosette water sampler at night in Lake Erie.This research involves intensively sampling inside and outside of:
  1. HABs
  2. hypoxic zones
  3. areas of combined HABs and hypoxia

Here are the questions this research is designed to answer:

  1. How does the composition of microbes, phytoplankton, zooplankton and fish differ among areas inside and outside of HABs, hypoxic zones and areas of combined HABs and hypoxia?
  2. How does the movement, behavior and distribution of higher consumers (zooplankton and fish) vary in the presence of one or both stressors? For example:
    1. Are these organisms “squeezed” between surface-dominated HABs and bottom hypoxia?
    2. Is diel vertical migration, or migration that happens between day and night, disrupted?
    3. Do higher consumers actively use HABs as a refuge from predation, or actively avoid them?)
  3. Do production and energy transfer between primary producers (microbes, algae), secondary consumers (zooplankton), and tertiary consumers (planktivorous fish) differ among areas?
  4. Does the quality of higher consumers decrease in the presence of one or both stressors?
  5. What role does food web transfer play in the accumulation of cyanotoxins (microcystin) in the edible tissue of fish?
Survey partners include:
  • U.S. EPA
  • Illinois-Indiana Sea Grant
  • Ohio State University
  • Department of Fisheries and Oceans, Canada

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