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CIB Horseshoe Crab Survey to begin in May

April 11, 2019

The Delaware Center for the Inland Bays is preparing for its Annual Horseshoe Crab Survey and tagging citizen science project. The project sends hundreds of volunteers to survey the number of horseshoe crabs found around the sandy beaches of the Inland Bays on each full and new moon in May and June. A training session for volunteers was held April 10.

Data from the center’s horseshoe crab survey is used by researchers to better understand the horseshoe crab, and to help measure the importance of Delaware’s Inland Bays to the stability of this iconic living fossil. Andrew McGowan, environmental scientist for the center, had an article published last spring in the national scientific journal Estuaries and Coasts, titled “Horseshoe Crab (Limulus polyphemus) Movements Following Tagging in the Delaware Inland Bays, USA.”

McGowan explored a new question about the movements of horseshoe crabs within the Delaware Inland Bays region, and recognized the importance of citizen scientists to the results of this study: “We could not have done this research without the dedicated citizen scientists who come out every year to tag and record crabs. It’s their efforts that have made this work possible.”

Horseshoe crabs can be found in many regions along the Atlantic Coast, including the Delaware Bay region, which spans from Barnegat Bay, N.J., to Chincoteague, Va. In all regions, horseshoe crabs are a regular sight each spring near sandy beaches that they use for spawning, but their long-term movements after the end of the spawning season are not well-studied.

Using data collected by citizen scientists, McGowan was able to confirm previous studies which demonstrated that long-distance migrations between neighboring regions are rare. “Only two of the more than 1,000 tracked crabs moved from the Inland Bays to the Long Island Sound region, even though the two regions are next to each other,” he said.  

McGowan also completed an original study which focused on the movement of crabs within the Delaware Bay region. The results showed a large amount of movement between bays within this area. The horseshoe crabs in the study stayed close to spawning beaches for about five days, but then often moved from one bay to another in a single year. It was common to see horseshoe crabs that were tagged in the Inland Bays move to the Delaware Bay and occasionally the coastal bays of Maryland, Virginia or New Jersey. This movement shows how important connected neighboring bays are to the population of horseshoe crabs within a region. Protecting natural shorelines of the Inland Bays will also help support the health of the larger regional populations.

For more information, call Amy Barra at 302-226-8105, Ext. 103, email abarra@inlandbays.org, or go to www.inlandbays.org.

 

 

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