Views from theTower NEWSLETTER
SUMMER 2018 | VOLUME 46 | NO. 2
Crazy about Horseshoe Crabs The Atlantic Horseshoe Crab (Limulus polyphemus) is an important keystone species of the Delaware Bay. As such, the horseshoe crab is depended upon by many other species participating in the ecosystem. Shorebirds such as the Red Knot (Calidris canutus), Ruddy Turnstone (Arenaria interpres), and the Sanderling (Calidris alba) depend upon the horseshoe crab’s tiny, green, protein-rich eggs deposited along the banks of the Delaware Bay for their own nutritional welfare. Some of these shorebirds make a 9,000 mile migration from their wintering grounds along the southern tip of South America to their breeding grounds in the Arctic tundra. Their journey is timed so they can take a rest along the shore of the Delaware Bay in order to feast upon this large concentration of horseshoe crab eggs. Unfortunately, the Delaware Bay’s horseshoe crab population has declined by 90% over the last 15 years mostly due to overharvesting and habitat degradation. As the number of horseshoe crabs have decreased, so have the number of eggs available for consumption by migrating shorebirds. Shorebird population numbers are therefore plummeting as well, as many cannot gain the amount of energy needed to complete their migrations.
by Shelby Schmeltzle
In an effort to address the Delaware Bay horseshoe crab situation, with proper permitting, The Wetlands Institute (TWI) collects fertilized horseshoe crab eggs from spawning beaches along the Delaware Bay and rears the eggs under controlled Photo by conditions in our aquarium. CariAnne Slotterback After about a month, joint initiative between TWI and the NJ eggs hatch and newly born horseshoe Division of Fish and Wildlife’s Aquatic crabs are maintained in their specially Education program. This program allows designed culture tanks consisting of two teachers across New Jersey to raise large chambers with netted lids that keep horseshoe crab hatchlings in specialized eggs inside the chambers while allowing tanks in their classrooms. In only its them to receive oxygenated seawater second year, the program currently and prevent unwanted fungal growth. has eight participating teachers, each The lower part of the system contains taking approximately 25 horseshoe fine-medium grain sand where larger crab hatchlings and 25 fertilized eggs, hatchlings reside for public viewing. resulting in approximately 400 horseshoe Enclosed in this cultured environment crabs going into classrooms throughout and free of predation, aquaculture New Jersey, more than doubling efforts dramatically increases horseshoe crab from the first year. In the coming weeks, survival both before and after the first the teachers will return their grown molts. These small crabs are kept in horseshoe crabs to TWI so we can release culture tanks until they are ready to begin them back into their natural habitat. feeding. From there, some are released at Want to join in a horseshoe crab release, their respective egg collection locations learn more about the Horseshoe Crabs and others enroll in the Horseshoe Crabs in the Classroom program or see the in the Classroom program, which is a horseshoe crab hatchery display? Then come on over to The Wetlands Institute every Thursday evening for Horseshoe Crab Mania Thursday where our educators give presentations focusing on horseshoe crabs, their conservation, and we release one of our larger horseshoe crab hatchlings. We look forward to seeing you!
wetlandsinstitute.org | 1075 Stone Harbor Blvd, Stone Harbor, NJ 08247 | 609.368.1211