North Carolina Sea Grant
Coastwatch Currents

Coastwatch Currents

January 20, 2015 | E-Ching Lee

By ANDREW GOFF

Posted Jan. 20, 2015

Born and raised in North Carolina, Andrew Goff is a biologist, adventurer, fisherman and environmentalist. He is pursuing a master’s degree in marine biology at the University of North Carolina Wilmington. His interests are related to coastal areas and the creatures that inhabit them. Goff currently is investigating the impact that land-use insecticides have on populations of blue crabs, primarily in North Carolinian estuaries. He hopes to develop better management strategies for regulating inputs of land-use compounds into the waterways that run through the state and empty into the ocean.

The project described below was funded by North Carolina Sea Grant. It also is featured in a UNC-TV NC Science Now story that looks at water quality issues in the mountains and the coast.

Two men with crab pot on pier.

Andrew Goff (left) and Nick Jernack deployed crab pots in the Cape Fear River in summer 2014. Photo courtesy Andrew Goff.

The blue crab fishery is North Carolina’s largest and most profitable, with more than 21 million pounds landed in 2013, according to N.C. Division of Marine Fisheries statistics. However, over the past decade, this fishery has declined from a high of about 42 million pounds in 2003.

The need to investigate the causes of this decline is important not only to the economy of North Carolina, but also to the health of marine and estuarine ecosystems along the southeastern Atlantic coast. In the lab run by Susanne Brander, an ecotoxicologist at the University of North Carolina Wilmington, we are investigating the health of blue crabs from different estuaries along the North and South Carolina coasts, incorporating analysis of water and sediment chemistry in those areas.

By doing so, we hope to provide insight into how pollutants can potentially affect these populations. Results from collections done between 2013 and 2014 indicate that crabs in more polluted estuaries are smaller and skew toward a male-biased sex ratio.

Compounds that enter waterways from agricultural, industrial and terrestrial uses are capable of exerting a wide range of negative influences on aquatic organisms. These compounds can mimic or interfere with naturally occurring substances in these organisms, such as hormones. They can cause complications that disrupt many of the biological processes within an organism, affecting growth, reproduction and/or the nervous system.

Blue crabs are aquatic invertebrates that are highly susceptible to chemicals used to kill insects on land. The extent of the damage wrought by these compounds as they enter aquatic environments is well documented for amphibians and fish, but is understudied and poorly understood for aquatic invertebrates. The importance of such an investigation is not restricted merely to impacts on aquatic organisms such as the blue crab, but rather applies to ecosystem-wide health.

Small crab under a stereoscope.

Goff is rearing juvenile crabs, such as this one viewed under a stereoscope at 10x magnification, to obtain preliminary data collection on growth rate and molting frequency in clean water. Photo courtesy Andrew Goff.

Currently, we are beginning to expose larval blue crabs to insecticides in the lab. Our goal is to establish relationships between exposure to insecticides, such as fipronil, detected in the eggs of females collected in 2013 and 2014 and determine how that affects proper growth and development.

Fipronil, an insecticide found in common pest-control products used for pets and in households, changes into the more toxic compound fipronil desulfinyl, when exposed to sunlight. My research involves exposing larval and juvenile blue crabs to different concentrations of these two compounds over a period of time and then using genetic markers to evaluate differences in development.

For some areas along the southeastern Atlantic coast, blue crabs occupy habitats that are sources of drinking water for municipalities, as well as recreational areas for boating and tourism. Very small concentrations of compounds entering waterways are capable of causing negative effects on a variety of aquatic invertebrates. Environmental concentrations of such substances also could threaten human populations over the long term. Therefore, establishing a link between concentrations of insecticides in coastal waters and the health of blue crab populations could provide us with an early indicator of human health problems that may occur in the future.

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