USF researchers study ghost crabs to find out more about impacts of Gulf oil spill

07/20/11 Andrea Lypka
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Questions about the impact of last year’s Deepwater Horizon oil disaster and the effectiveness of the beach cleanups remain to be answered by researchers. A team of researchers from the University of South Florida say that their study on ghost crab populations and sediments of Gulf beaches might answer these questions.

Susan Bell, professor of biology and chair of the Department of Integrative Biology, and her research team will start to document the Deepwater Horizon spill’s impact on the beaches and their inhabitants.

“This project is a continuation of the work that we have been doing on the beaches up in the Florida Panhandle and in Alabama, many of which were oiled by the Deep Water Horizon oil spill which we all have seen pictures of. We have been working on the environmental impacts of the oil and on the animals that have been living on the beach sands and we also take a closer look at the food webs of those sandy beaches,” Bell said.

Her students have been monitoring the beaches for a year from Florida’s Atlantic Coast to North Carolina to find out whether the oil spill has affected populations of animals living on beach shores. This time, they will examine whether the food web or feeding relationships of plants, small crabs, clams, and other critters have been altered on beaches.

“And or if we see any kind of shifts in the feeding relationships that normally exist on the beach have changed once the oil comes in because of some environmental impacts that are displayed by it. We also have been doing work on non oiled beaches and we used them as comparisons to the oiled beaches,” she said.

Bell was awarded one of seventeen grants from the BP-funded Gulf of Mexico Research Initiative. She says key players in this research are students and faculty, including post-doctoral researcher, Alex Tewfik and USF geologist Ping Wang.

“We will be sending a team up on Thursday this week, a group of undergraduate and graduate students to do work in the Panhandle over the next month and a half additional samplings will be done on other beaches, too,” she said.

Starting this week, researchers will study ghost crabs. These organisms live in burrows on the beach during the day and they come out at night to feed on other invertebrates, including some insects, small clams, and mole crabs.

“Because they are relatively easy to see, we can also do some chemical analysis of their muscles and we can tell what they have been eating based on some signatures we have been using. Ghost crabs serve as food for birds and raccoons, thus they are an important link on the food chain,” she said.

These critters feed off of seaweed and other material that washes up on the beach, called wrack. During beach cleanups, some of the wrack was removed because it was contaminated with oil. Bell says that their study will answer whether removal of the wrack negatively impacted the food web. Researchers will also study sediments in which mole crabs and clams live in the swash zone where the waves wash back and forth on the beach.

“We have been noticing and trying to quantify the presence or absence of small tar balls in those sediments,” Bell said.

However, research might difficult to accomplish in hurricane season.

“We are concerned whether during these storm events we will see oil that has been sitting offshore or maybe in the near shore area buried in the shallow sediments, whether when the storms come this oil will be redeposited on the beach,” she said.

Bell’s research results will be available at the end of the fall.

Full disclosure: Dr. Bell was a dissertation adviser for WMNF's assistant news & public affairs director Seán Kinane.

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