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2014-2016 Research Projects: Sustainable Fisheries and Aquaculture

Project: Vibrio parahaemolyticus virulence and its magnification in the Eastern Oyster, Crassostrea virginica

Principal Investigator

Charles Lovell, University of South Carolina

Project Number

R/CF-20

Research Description

Vibrio parahaemolyticus is a growing problem for seafood safety. Increasingly, human exposure to V. parahaemolyticus has led to an increasing number of cases of seafood-associated gastroenteritis. Increasing coastal water temperatures are producing more frequent and more widespread outbreaks of this pathogen worldwide and in the southeast. The conditions leading to the magnification of virulent strain bacterial populations in oysters are unknown and the extent of this magnification has not been quantified. The researchers will use PCR (polymerase chain reaction) to quantify virulent V. parahaemolyticus in thermally stressed Eastern Oysters, Crassostrea virginica. This will aid researchers in determining if virulent strains are selected in oysters, and if this is impacted by elevated in-shell oyster body temperature.

Determining the impacts of thermal stress on oyster V. parahaemolyticus burdens is essential to assuring oyster safety to consumers. The results will also provide the necessary quantitative evidence for adoption or modification of policies for regulating the oyster harvest.

The objectives of this study are to determine (1) if selection within oysters increases V. parahaemolyticus population sizes and thus potential for transmission to humans of virulent V. parahaemolyticus strains and (2) if high environmental temperatures and aerial exposure of oysters, which have direct effects on in-shell oyster body temperature, result in increased V. parahaemolyticus population sizes and potential for transmission of virulent V. parahaemolyticus strains.

Research Results

Klein SL and Lovell CR. “The hot oyster: levels of virulent Vibrio parahaemolyticus strains in individual oysters ,” 2017, FEMS Microbiology Ecology.

Klein, SL. Doctoral dissertation, “Ecology and Virulence Capabilities of Vibrios Isolated From the Pristine North Inlet Estuary ,” May 2018, University of South Carolina.

Contact for Questions

Charles Lovell (lovell@biol.sc.edu)

Project: Pilot deployment of a novel substrate to create oyster habitat in Port Royal Sound and the ACE Basin National Estuarine Research Reserve (NERR), South Carolina, USA

Principal Investigator

Peter Kinglsey-Smith, S.C. Department of Natural Resources (SCDNR)

Research Description

In South Carolina, research has shown that the oyster (Crassostrea virginica) population is limited by the availability of hard substrate suitable for settlement.  In recent years, the SCDNR has experimented with alternative substrates. A cement-coated crab trap method has proven to work extremely well at recruiting oysters. The SCDNR collects abandoned and donated crab traps and coats them with a thin layer of cement in order to create a hard substrate that larval oysters require for settlement, recruitment, and growth.  

In the current project a potential method of introducing a larger-scale, intentionally fabricated, and more cost-effective structure, using cement-coated mesh materials was evaluated as a viable option for future oyster reef restoration by private residents. Thirty modified crab traps were deployed in the spring of 2016 at each of the two sites; the Ashepoo-Coosaw Cut in the ACE Basin NERR and the Chechessee River in Port Royal Sound.  This created 480 square feet of new reef surface and served to increase oyster reef habitat in these watersheds. This was performed by SCDNR researchers, but would be feasible by an individual home owner wishing to adopt this strategy to create a living shoreline adjacent to his/her property to address erosion concerns, as an alternative to a bulkhead or seawall.  Installation of the reef structures required manual efforts but no machinery.  One person could easily pick up and move a cement-coated modified crab trap. 

Oyster larvae settled onto and attached to the modified traps at both the ACE Basin and Port Royal sites showing that they work at attracting larval oysters. Continued monitoring of these structures will better inform researchers and interested homeowners as to their effectiveness to serve not only as reef habitat but also to support shoreline protection as living shorelines.

Contact for Questions

Peter Kingsley-Smith (kingsleysmithp@dnr.sc.gov)

Project: A marine larval culture facility for the Okeanos Research Laboratory

Principal Investigator

Andrew S. Mount, Clemson University

Research Description

The initial aim of the project was to condition brood stock oysters for both control and ocean acidification treatment scenarios. Unfortunately, Clemson University’s Okeanos Research Laboratory’s pre-existing aquaria and holding facilities were not sufficient for this task and the effort resulted in failure. At this point, we realized that our first priority was to build the holding and larval culture facility. All subsequent efforts were directed to the building of a larval culturing facility.

Funding enabled the laboratory to obtain the necessary parts and components to build and an in-house marine invertebrate larval culture facility which will enable cellular biology based ocean acidification experiments on early-stage larval marine invertebrate animals including oysters. With the completion of the facility, the lab now has the capability to maintain oyster broodstock, grow algal cultures for feeding, perform larval spawning and growth and set up ocean acidification experiments that with have both control and two different CO2 treatment levels.

Contact for Questions

Andrew S. Mount (mount@clemson.edu)