Anna Sorgie

Abstract:

Horseshoe crabs Limulus polyphemus range along the East Coast of the United States and are facing declining populations throughout New England. The project “Assessing Atlantic Horseshoe Crab (Limulus polyphemus) Population Structure within Southern New England” involves tagging and taking a tissue sample for genetic analysis as a metric to determine the discreteness of several local populations. It has been assumed that genetic sampling does not harm the animals. We investigated whether tissue sampled adult horseshoe crabs would exhibit higher short-term mortality rates than unsampled adults, as well as monitored their recovery and behavior over the course of 4 weeks. All crabs were obtained from a commercial fish trap operation in Rhode Island and then were transported to a laboratory for the experiment. Genetic sampling involved amputating the first segment of a left walking leg with shears. Overall mortality of tagged and untagged crabs held in flow-through tanks for 38 d was nonexistent with a (0% mortality among 18 genetically sampled crabs; 0% mortality among 4 unsampled crabs). Bleeding ceased in all but one crab within one week. Normal behavior, involving mating and feeding, were observed. Our results indicate that genetically sampled adult horseshoe crabs have the same potential to survive as unsampled crabs through the spawning season (∼30–45 d).