What is the project about?
Red swamp crayfish (Procambarus clarkii) are a species native to the southern U.S. and northern Mexico. However, they are a worldwide invader, and are established on every continent besides Australia and Antarctica. In July of 2017, the Michigan DNR received multiple reports of red swamp crayfish in two separate locations in Michigan. Since this time, we have worked closely with the Michigan DNR to develop control and eradication plans for this species. As of September 2024, we have found red swamp crayfish in more than 46 waterbodies around the state focused on four epicenters--three in southeast Michigan, and one in southwest Michigan. The Roth lab seeks to quantify the distribution of red swamp crayfish in Michigan and implement control and eradication strategies. In addition, we work with the molecular ecology lab led by Dr. Kim Scribner to determine the sources and relatedness of the Michigan populations to further understand the invasion dynamics of this species.
What kind of data do we collect? |
We collect trapping, telemetry, ecological monitoring, chemical treatment, burrow scoping, soil characteristic, and other site biological and physical data to better understand the red swamp crayfish's life habits. We want to know what their impact is to ecosystem services and communities, and how they are using it.
Telemetry is used to track the movement of crayfish.
Our master's student, Colin Assenmacher, is looking into soil characteristics as a way to determine burrowing behaviors of the red swamp crayfish. Check out the grad projects page for his results!
Ecological monitoring sample bottles
Along with our ecological monitoring, we also collect macrophyte cover data to compare to aerial imagery. We are curious how the macrophyte cover is changing over time with red swamp crayfish presence.
We use a borescope in the burrows to try and measure occupancy.
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The reason we get to do this work:
the red swamp crayfish! 
Soil characteristics equipment
Part of our ecological monitoring is macrophyte collection. We use a rake head to collect the submersed vegetation and then we identify it!
That's a lot of crayfish! This trap is called a Gee Minnow trap. It is baited and used around the world to collect crayfish.
We use HOBOware's dissolved oxygen loggers (above) and light/temperature pendants (right) to collect site data every 15 minutes when we can't be in the field!
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Trapping gives us an idea what the population looks like. It also helps us remove a large number of crayfish! 
Trapping
Fish surveys do exactly that: survey fish! These surveys help us understand the fish communities at our field sites.
Our undergraduates hard at work doing some ecological monitoring! We use a ponar dredge, dipnet, and rake head to collect macroinvertebrate and macrophyte samples.
This is an Additional Partition Artificial Refuge Trap, or APART for short. We use them in conjunction with the Gee Minnow traps to collect a more representative sample of the crayfish population.
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How are we adapting our management?
Chemical treatments
As with any aquatic invasive species, red swamp crayfish are hard to manage. We've put years of work into trapping these guys, so now we're trying new things. In the past few years, we've shifted our management to a combined approach of trapping and chemical treatments. We want to kill the largest number of crayfish in one go, and trap for surveillance afterwards. We use an ExciteR chemical (with special permissions from EGLE and EPA) to treat our landlocked sites. While the chemical can be effective at killing the crayfish, we are still learning how to reach the crayfish in burrows or deep in the macrophytes.
(Check out our blog post in 'What's new in the Roth lab' for more information.)
As with any aquatic invasive species, red swamp crayfish are hard to manage. We've put years of work into trapping these guys, so now we're trying new things. In the past few years, we've shifted our management to a combined approach of trapping and chemical treatments. We want to kill the largest number of crayfish in one go, and trap for surveillance afterwards. We use an ExciteR chemical (with special permissions from EGLE and EPA) to treat our landlocked sites. While the chemical can be effective at killing the crayfish, we are still learning how to reach the crayfish in burrows or deep in the macrophytes.
(Check out our blog post in 'What's new in the Roth lab' for more information.)
Dr. Brian Roth even comes out to help with treatments! It's an all-hands-on-deck situation. Here he is taking a selfie with the lead field technician, Mackenzie Thompson.
Carcass crew making their rounds (above) and recording species data (below).
Pulling the deployment setup for triple rinse.
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Per state and federal requirements, we set up signs around the treated waterbodies to inform the public of our efforts for safety and informational reasons.
Wand crew (pictured on the left/below) gets in the hard to reach areas while deployment crew (pictured on the right) deploys the set ups.
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Bioassay/water sample crew taking YSI readings, water samples, and checking bioassay crayfish to see if they survived the treatment (above and below).
Water refill crew awaiting a call from the triple rinse crew to deliver water.
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Habitat modification and stocking
We are brainstorming ideas for habitat modification and stocking native fish and crayfish species back into the waterbodies. Our hope is to make the habitat unsuitable for red swamp crayfish re-establishment, but suitable for our native crayfish and fish species. Check back in later to see what we do!
Habitat modification and stocking
We are brainstorming ideas for habitat modification and stocking native fish and crayfish species back into the waterbodies. Our hope is to make the habitat unsuitable for red swamp crayfish re-establishment, but suitable for our native crayfish and fish species. Check back in later to see what we do!
How are we funded?
This project is funded through the Great Lakes Restoration Initiative and the Michigan DNR, and supports undergraduate and graduate students, technicians, research supplies, and travel to invaded sites.
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