Decapods

Project

Summary

Project Summary

The purpose of this project was to demonstrate the utility of the existing National Estuarine Research Reserve System (NERRS) as a surveillance platform for invasive species. Decapod crustaceans were selected as test organisms that are relatively easy to sample, are currently known to be invading US estuaries and can capture the interest of the public to help educate the public at large about invasive species and invasion biology. The project was designed to establish biological baselines for both native and non-native decapod crab species in US estuaries.

Methods

Eight reserves and the South Carolina Department of Natural Resources Marine Resources Research Institute participated in the study.

ACE Basin NERR - Dr. Elizabeth Wenner, Research Coordinator
Elkhorn Slough NERR - Dr. Kerstin Wasson, Research Coordinator

Guana Tolomato Matanzas NERR - Dr. Richard Gleeson, Research Coordinator

North Inlet-Winyah Bay NERR - Dr. Erik Smith Research Coordinator

Padilla Bay NERR - Sharon Riggs, Stewardship Coordinator

Rookery Bay NERR - Dr. Michael Shirley, Research Coordinator

Sapelo Island NERR - Dorset Hurley, Research Coordinator

South Carolina Department of Natural Resources - Dr. Loren Coen, Senior Scientist

South Slough NERR - Dr. Steve Rumrill, Research Coordinator

Click on the site names below to view project data.

7 replicate plastic trays (60x50 cm) lined with mesh and filled with appropriate substrate for each area were placed intertidally at each reserve.

Trays were sampled quarterly: Fall, Winter, Spring, Summer (2002-2003).

All decapods within the trays were identified, measured and counted.

All data were sent to North Inlet-Winyah Bay (NIWB) NERR for analysis.

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Results

Only 2 invasive species were detected across reserves, Petrolisthes armatus on the East Coast, and Carcinus maenas on the West Coast.

P. armatus was detected at all participating Reserves located along the southeast coast of the US. Note that this project did not include Reserves located north of South Carolina.

Strong differences were observed across sites:

The highest crab diversity was observed at Padilla Bay, WA, ACE Basin, SC and SC DNR with 3-4 native species per tray on average. By comparison, all other sites had 1-2 species per tray. Other crabs are undoubtedly present in these reserves, but some crab species are not caught efficiently by the trays, i.e. Callinectes sapidus. Hence, these and other species such as Charybdis hellerii or Eriocheir sinensis may be missed with this method.

Invasion levels were relatively low on the West Coast and in Florida, medium at NIWB, SC, and high at other southeast sites. Strikingly, >60% of all crabs collected in the ACE, SC-DNR and Sapelo Island, GA, southeast sites were invasive.

Figure1. Summary Data on Southeastern Sites, Featuring Petrolisthes armatus and Eurypanopeus depressus

Petrolisthes armatus - this invasive species was abundant during winter 2002 (probably as a result of recruitment and growth during autumn), but it was not abundant the following summer at the northern sites. The species rebounded from winter early in the season at Rookery Bay, while populations at northern sites had not yet rebounded by summer. The invasion front is clearly visible, with North Inlet-Winyah Bay apparently north of the spread. Some site to site variability is evident, with most relatively similar, but densities are always highest at SC-DNR.

Eurypanopeus depressus - the numerically dominant native species in the southeast. Very little seasonal fluctuation is noted in Florida. Further north, population densities appear lower in winter than in the following summer.

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Conclusions

We documented the occurrence of two invasive crabs at several NERR sites along with information about native species at each site. The presence of P. armatus in GA and SC documents the invasion of this sub-tropical crab into new habitats north of its native range.

P. armatus is believed to be native to the Gulf of Mexico and Florida's Gulf Coast but was collected in Atlantic habitats well north of its range as of 1993 (Cape Canaveral, FL).

This study demonstrated the value of both the NERR sites and the NERR System, with data collected from nine reserves in six different states and is a unique model of a rigorous, quantitative monitoring program at a broad geographic scale.

Results from this pilot study provide valuable information about native and invasive decapods.

The NERR System network provided an excellent platform for collection, analysis and dissemination of invasive decapod information. Continued support provided throughout the network would provide valuable information for improving management and protection of estuarine resources.

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