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The Plight of the Ancient Horseshoe Crab

Written by The Two River Times. Posted in Letters & Commentary

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The Plight of the Ancient Horseshoe Crab

Published on August 17, 2012 with No Comments

By Michele S. Byers

It’s fitting that a sculpture of the horseshoe crab, which will become part of an artificial reef off the coast of Mantoloking in Ocean County, will be the world’s largest undersea artwork.

New Jersey artist, scuba diver and marine biologist Christopher Wojcik created the 47-foot-long, 25,000-pound concrete sculpture of this ancient animal to serve as a unique habitat for fish, crabs, lobsters, mussels and other marine life. Depending on weather and ocean conditions, it will be placed on the sea floor sometime this month.

It’s beyond cool that a Guinness Book of World Records-size artwork will serve a conservation purpose. But better still, it draws attention to the plight of the horseshoe crab, a prehistoric creature threatened by overharvesting.

The story of the horseshoe crab’s important role in the ecology is engagingly told in “Life Along the Delaware Bay,” a new book by Lawrence Niles, Joanna Burger and Amanda Dey, three Ph.D. scientists who have collectively spent more than 75 years studying shorebirds and other coastal birds in New Jersey.

The photo-packed book was published this summer by Rutgers University Press and details the “elegant relationship” between the prehistoric, helmet-shaped horseshoe crab and the shorebirds that depend on crab eggs for survival – especially the long-distance migratory sandpiper known as the “red knot.”

The horseshoe crab “has survived virtually unchanged for 445 million years,” explained the authors. It emerged as a species before the separation of the continents – millions of years before dinosaurs came along – and has survived ice ages and meteor strikes that wiped out other species.

Each spring, hundreds of thousands of horseshoe crabs mate along the Delaware Bayshore, where females deposit billions of eggs in the sand.

While the crabs mate, red knots make their incredible migration. Red knots spend our winter at the southern tip of South America, but breed each summer in the Canadian arctic – a journey of over 7,000 miles.

Red knots arrive at the Delaware Bayshore, thin and depleted, and fall upon what the authors describe as an “all-you-can-eat buffet” of rich horseshoe crab eggs. The birds must gain weight not only to fuel their flight to the arctic, but also to develop and incubate their eggs. The frozen tundra awaiting them is virtually devoid of food almost until the young hatch.

Red knots aren’t the only birds that depend on horseshoe crab eggs – others include ruddy turnstones, sanderlings and semipalmated sandpipers. Horse­shoe crab eggs and young are also eaten by small fish and eels, as well as loggerhead turtles.

Because of their importance, horseshoe crabs are known as a “keystone species” in the food web.

“Without keystone species, other species in the web may decline or collapse, causing cascading effects on even more animals,” wrote the authors.

But horseshoe crab populations have dropped precipitously during recent decades due to overharvesting of the crabs for bait.

In the spring of 2008, New Jersey banned the harvest of horseshoe crabs from its beaches and waters to ensure an abundance of crab eggs needed by the red knot for food. But unfortunately, other states that comprise the Atlantic States Marine Fisheries Council have not.

It’s not too late to restore horseshoe crab populations in the Delaware Bay, but it will take an end to what the authors call “human shortsightedness.”

For more information about what can be done to help horseshoe crabs, go to the Ecological Research and Develop­ment Group website at www.horseshoecrab.org. To learn more about “Life Along the Delaware Bay,” visit the Rutgers Uni­versity Press website at rutgerspress.rutgers.edu/acatalog/life_along_the_delaware_bay.html.

And to find out more about preserving New Jersey’s land and natural resources, visit the New Jersey Conservation Foundation website at www.njconservation.org or contact me at info@njconservation.org.

Michele S. Byers is the executive director of the New Jersey Conservation Foundation.

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