Status of the tidewater mucket, Leptodea ochracea (Say, 1817) (Bivalvia : Unionidae), in Halfway Pond, Massachusetts, USA

The tidewater mucket, Leptodea ochracea (Sav, 1817), is distributed along t he Atlantic coast of North America and is often found on sandy substrates w ith little or no flow. Halfway Pond, in Plymouth, Massachusetts, is one of the few remaining habitats in Massachusetts for this species, but live spec imens have not been collected there since 1981. In summer 1995, the pond wa s surveyed in an attempt to determine if the tidewater mucket had been exti rpated. Of 213 live unionids collected. comprising 6 different species, onl y 1 specimen was identified as L. ochracea. The single specimen was found i n the Agawam River outflow area in the southwest center of the pond along w ith 4 of the 5 other species of unionids occuring in the pond. This high fl ow area had a high proportion of benthic macrophytes in a sandy substrate-t ypical habitat for L. ochracea. Other species found in the pond include Ell iptio complanata (Lightfoot, 1786), Lampsilis radiata radiata (Gmelin, 1791 ), Alasmidonta undulata (Say, 1817), Strophitus undulatus (Say, 1817), and Pyganodon cataracta (Say, 1817). This study confirms the decline of L. ochr acea in Halfway Pond, Massachusetts, over the last 15 years. If not already gone, this species may disappear from the pond once the remaining individu als die.