Horseshoe crabs as a flagship species for the conservation and restoration of estuarine, beach and mangrove habitats

Horseshoe crabs (HSC’s) have a 445 million year fossil record, but the four living species face multiple threats including the loss of spawning and nursery habitats through coastline development and overharvesting for use as food, bait and biomedical purposes. Mangrove HSC’s (Carcinoscorpius rotundicauda) are imperiled by the decimation of mangroves throughout Asia. Sandy estuarine beaches are spawning sites for Tachypleus tridentatus, T. gigas, and Limulus polyphemus, and shoreline armoring degrades or eliminates suitable habitat. Likewise, mudflats and salt marsh pans, recognized as important juvenile nursery habitats, are also threatened by anthropogenic factors. With global sea level rise exacerbating coastal habitat loss, it is imperative that we find sustainable solutions. The IUCN HSC Specialist Group has promoted the concept of HSC’s as a flagship species for wise management and restoration of the coastal zone. We discuss examples from Asia and North America demonstrating how HSC’s have helped increase public support for the conservation of coastal habitats and HSC themselves. Recent research and restoration activities involve alternative shore-protection approaches, such as ‘living shorelines’ that dampen wave energy while maintaining viable habitat. Captive breeding programs in the US (e.g. Molloy College), India, Hong Kong and elsewhere will further augment possible HSC restoration efforts.