Posts Tagged ‘crabs’

Skidaway Institute scientists study long-term effects of Gulf oil spill

October 1, 2013

As the Gulf Coast continues to recover from the effects of the 2010 Deepwater Horizon oil spill, scientists from the University of Georgia Skidaway Institute of Oceanography are continuing to look into the long-term effects of the spill on coastal marine life. A team led by Skidaway Institute professor Richard Lee recently completed preliminary work into the effect dispersed and emulsified oil has on blue crabs and shrimp. The project includes vital information from fishermen and crabbers in the Gulf.

Lee and his research associate, Karrie Bulski, are exposing blue crabs and grass shrimp to emulsified oil in sediment and then determining how this oil affects molting, or periodic shedding that allows shrimp and crabs to grow. To test this, emulsified oil is added onto sediment inside the tanks that house the crabs. The crabs are also fed squid that has been contaminated by the emulsified oil. Preliminary research results show egg and embryo production was reduced in female grass shrimp exposed to food and sediment infused with emulsified oil.

 Working with Anna Walker, a pathologist at the Mercer University School of Medicine, they found that blue crabs exposed to emulsified oil showed changes in their blood cells, especially cells related to the immune system. Lee and his team speculate that the immune systems of those crabs may be compromised, making the crabs more susceptible to infection and disease.

Researchers are also testing effects of oil treated with dispersants. In the case of the Deepwater Horizon blowout, millions of gallons of chemical dispersants were sprayed over the surface and subsurface of the Gulf. These chemicals disperse the oil into micro-droplets. In this project, dispersed oil droplets are added to petri dishes containing embryos of crabs and shrimp to test their effects on development.

Preliminary results show grass shrimp embryos exposed to suspensions of dispersed oil affected the hatching and molting of the shrimp embryos. Work on this project by Sook Chung at the University of Maryland indicates that molting hormones and molting regulating genes are affected in grass shrimp embryos exposed to dispersed oil.

Lee is working with scientists at the University of Southern Mississippi to provide the outreach portion of the project, which includes working with crabbers, fishermen and others in the Gulf ecosystem to understand the long-term effects of the spill and discover ways to manage them.

Richard Lee works with the tanks containing crabs and grass shrimp in his laboratory at Skidaway Institute of Oceanography.

Richard Lee works with the tanks containing crabs and grass shrimp in his laboratory at Skidaway Institute of Oceanography.

“In the outreach part of the project, scientists at the University of Southern Mississippi are going to some of the affected communities and recruiting people to participate in a series of one-day workshops,” said Lee. “At these workshops, scientists are explaining the effects of the oil on crabs and shrimp.”

So far, workshops have been held in Ocean Springs, Miss. and included charter boat captains, crab and shrimp fishermen, eco-tourism operators, and even teachers and artists from Biloxi, Miss. and Bayou La Batre, Ala.

“It was very interesting,” said Lee. “From the scientific and economic standpoints, there are many aspects as to how oil is affecting these communities.”

According to Lee, one issue facing the Gulf coast communities is rumors about seafood safety are often much worse than reality. In Louisiana and parts of Mississippi, where a lot of the oil came ashore, there is a perception that people should not eat the seafood there. But, there is very little evidence of any contamination in commercial shellfish.

Lee describes the people who attended the workshops as passionate, involved and worried about their communities. “They are worried that the oil will change things, but most agree that the ecology was not destroyed and it’s not the end of a way of living,” he said. “It’s my opinion that the Gulf will recover.”

Lee and his team plan to complete their project and publish their results early next year.  

 The study is funded through a $500,000 grant from the Environmental Protection Agency. The team includes Chung from the Institute of Marine and Environmental Technology at the University of Maryland, Harriet Perry and Christopher Snyder from the University of Southern Mississippi’s Gulf Coast Research Laboratory, and Walker, at the Mercer University School of Medicine.

 

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Deepwater Horizon oil spill prompts Skidaway Institute research

December 11, 2012

The 2010 Deepwater Horizon oil spill in the Gulf of Mexico is the impetus behind a research project at the Skidaway Institute of Oceanography to study the effects of spilled oil on blue crabs and grass shrimp.

The Deepwater Horizon oil spill as viewed from space./ NASA Photo

The Deepwater Horizon oil spill as viewed from space./ NASA Photo

The project is looking at two forms of oil. The first, emulsified oil, is an oil-water mixture produced by wave turbulence.  The oil doesn’t change chemically, but the emulsification produces a thicker, more viscous mixture.

“Because the emulsified oil is so much thicker, it becomes a much more difficult clean-up issue, especially if it is washed ashore,” said Skidaway Institute professor Richard Lee, the chief scientist on the project.

Lee and his team are exposing blue crabs and grass shrimp to emulsified oil in sediment and then watching to see how this affects their molting, which is the way the shrimp and crabs grow.

The second focus is on oil that has been treated with dispersants. In the case of the Deepwater Horizon spill, millions of gallons of chemical dispersants were sprayed over the surface of the Gulf to disperse the oil slick. These break the oil down into micro-droplets. Dispersed oil forms a underwater plume that can extend for many miles.

Richard Lee works with the tanks containing crabs and grass shrimp in his laboratory at Skidaway Institute of Oceanography.

Richard Lee works with the tanks containing crabs and grass shrimp in his laboratory at Skidaway Institute of Oceanography.

In the laboratory, the researchers are adding emulsified oil into the tanks containing the crabs and also feeding the crabs squid that has been contaminated by the emulsified oil. Dispersed oil droplets are added to tanks containing embryos of crabs and shrimp.

“What we are trying to determine here is just how the exposure to dispersed or emulsified oil affects the growth and molting crabs and shrimp,” said Lee.

The scientists selected grass shrimp and blue crabs for the study because of the important places they occupy in the marine food web. Although grass shrimp are not typically harvested as a commercial product, they are abundant in salt marshes and estuaries, and are an important food source for many fish. Blue crabs are also a food source for many fish in addition to having value as a commercial catch.

The study is funded by a $500,000 grant from the Environmental Protection Agency.

Lee is working with research associate Karrie Bulski at Skidaway Institute. The team also includes Sook Chung from the institute of Marine and Environmental Technology at the University of Maryland, and Harriet Perry and Christopher Snyder from the University of Southern Mississippi’s Gulf Coast Research Laboratory.

Sook is looking at the crab and shrimp at a molecular level. “We believe that the genes that regulate molting will be affected, and the crab and shrimp will not molt properly,” said Lee. “Hormone regulation and its relationship to contaminant exposure is something we need to learn more about, and Dr. Sook carries out that kind of research.”

The researchers will also send tissue samples, primarily from the shrimp and crab’s endocrine organs, to another researcher, Anna Walker, at Mercer University School of Medicine to look for physiological or pathological changes.

Another major part of the project will be to explain the results of the study to the public, especially the fishermen whose livelihood depends on a healthy marine ecosystem.  A significant part of the grant, $80,000, is designated for the establishment and implementation of a Community Outreach for Accurate Science Translation teams in four communities along the north central Gulf of Mexico coast.

“This is primary role for the team from the University of Southern Mississippi,” said Lee. “They will develop public presentations on the project and the results to educate them on what this all means to them.”

The project will run through 2013.

Skidaway scientists study drought effects on salt marshes, crabs

October 19, 2011

The Savannah Morning News had a nice story over the weekend on the effect of the regional drought on salt marshes. A couple of our scientists’ work was included. Credit environmental reporter Mary Landers.