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Females begin reproduction later than many other species.
© Robert Barlow |
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This species matures slowly, and doesn't begin to reproduce until around age ten. It's also long-lived. These factors lessen the effect of a single or several poor spawning years, so horseshoe crab populations tend to be fairly stable. It also means that serious, long-term impacts on the population will take a decade to become fully apparent.
Habitat Degradation
It is the absence of inlets or other breaks in the Delaware Bay shorefront that makes it an ideal habitat for horseshoe crabs. Environmentalists and researchers now believe that much of the recent population decline can be attributed to severe habitat degradation on the New Jersey side of the Delaware Bay, in the form of man-made inlets and sandbars. These artificial breaks reduce beach sand deposits, and large areas of mud flats form behind the breached shorefronts. Huge numbers of horseshoe crabs--three hundred thousand by some estimates--have been observed entrapped in these back-marsh mud areas. The adult crabs are stranded and die, and their eggs do not develop in the mud.
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