Annual Horseshoe Crab Census – Citizen-Scientist Opportunity
Since 1991, the Wetlands Institute has brought scientists and volunteer citizens together to conduct censuses of the ecologically vital horseshoe crab population on the New Jersey side of Delaware Bay. These censuses take place during May and June and are central to our understanding and responsible management of this ancient marine creature. We welcome members of the public to join us as we contribute to the critical effort to monitor Delaware Bay’s spawning horseshoe crab population.
Spawning horseshoe crabs on a Delaware Bay beach
Horseshoe crabs are ‘living fossils’, the last survivors of a group of organisms that first appeared in the fossil record some 300 million years ago. Delaware Bay has the largest population of horseshoe crabs (Limulus polyphemus) in the world.
Besides their extraordinary antiquity, horseshoecrabs are also of paramount importance to human health. Their blood contains a clotting agent, LAL (Limulus Amoebocyte Lysate), which provides a fast, reliable test for the presence of infectious bacteria in drugs, as well as prosthetic devices such as heart valves and hip replacements.
Horseshoe crab eggs
And their eggs, deposited along the high tide line of Delaware Bay beaches, provide food for vast flocks of shorebirds, such as red knots, which every spring make long distance migrations from the southern tip of South America to Arctic nesting grounds (around 9,000 miles). Some studies suggest that nearly 80% of the red knot population stops at Delaware Bay to refuel on horseshoe crab eggs before continuing on their epic journey north. It is no wonder Delaware Bay is recognized as a “Site of Hemispheric Importance to Shorebirds.”
Unfortunately, overharvesting of female horseshoe crabs by commercial fishermen, coupled with loss of spawning habitat resulting from beach erosion associated with sea level rise, has resulted in a precipitous decline in the Delaware Bay horseshoe crab population, and therefore the number of eggs available to feed migratory birds. This, in turn, has led to a dramatic decrease in the size of annual red knot migrating populations, to the point that red knots have been proposed for federally endangered status.
Horseshoe crabs occupy a critical niche in both the ecology of Delaware Bay and human pharmacology. They provide incalculable services and their population decline has catastrophic implications.
Despite the horseshoe crab’s importance, scientists did not know much about its population status until relatively recently. In 1990, Delaware Sea Grant organized the first census of breeding horseshoe crabs in Delaware Bay. Now, every spring on several peak spawning days (in May and June), volunteers donate their time to count crabs on twenty five key Delaware Bay beaches in Delaware and New Jersey. The Wetlands Institute is annually responsible for monitoring two of these beaches.
Occurring during new and full moons, at high tide and at night, horseshoe crab spawning is a remarkable spectacle. Scientists and student research interns from The Wetlands Institute, together with volunteers from the general public, gather the required data using protocols adopted bay-wide for this census.
Counting spawning horseshoe crabs using protocols adopted for the baywide census
Partaking in this activity acquaints participants with a spectacular display of breeding activity in an extraordinary species that they could not see anywhere else in the world. It also provides them with an exceptional example of a complex conservation issue whose outcome remains uncertain. By collaborating with efforts of the general public, the benefits of citizen-based conservation activities become clear. Education and public involvement are key components to the most effective wildlife conservation programs. Everyone can play a part. It is as easy as joining us for an evening stroll on the shores of Delaware Bay.
Sunset on Delaware Bay during a horseshoe crab survey
The crew will meet at The Wetlands Institute at the times listed below. If you plan to attend, or would like more information, please contact Research and Conservation Coordinator Katie Sellers at conservation@wetlandsinstitute.org or by calling the Institute at (609) 368-1211.
2013 Meeting Dates and Times:
May 7, 2013 – 7:00 pm
May 9, 2013 – 8:20 pm
May 11, 2013 – 9:35 pm
May 23, 2013 – 7:00 pm
May 25, 2013 – 8:45 pm
May 27, 2013 – 10:30 pm
June 6, 2013 – 7:15 pm
June 8, 2013 – 8:30 pm
June 10, 2013 – 9:45 pm
June 21, 2013 – 6:40 pm
June 23, 2013 – 8:30 pm
June 25, 2013 – 10:17 pm
