P3.55 Friday, Jan. 6 Response to adult conspecific odor is modulated by salinity in metamorphosing megalopae of the fiddler crab Uca minax KAINI, P*; SHRESTHA, S; ROBERTS, B; ZHU, N; BRODIE, R; Mount Holyoke College; Mount Holyoke College; Mount Holyoke College; Mount Holyoke College; Mount Holyoke College email@example.com
The complex lifecycle of decapod crustaceans involves a free swimming larval stage and a benthic adult stage. Larvae of the fiddler crab Uca minax are spawned in freshwater and low salinity adult habitats along tidal rivers, then travel downstream to the coast where they complete larval development in the marine plankton. After metamorphosing to the megalopal stage, they return to inland tidal creeks where they metamorphose again into juvenile crabs and remain as adults. Previous studies have demonstrated that adult conspecific odor is a potent metamorphic cue for megalopae. However, in natural environments, adult odors could be advected downstream during ebb tides into high salinity areas. Because a response to odor alone could lead megalopae to settle and metamorphose in inappropriate areas, we hypothesized that megalopae would not respond to conspecific odor unless they were in a low salinity environment. In a laboratory experiment, we found that megalopae delayed metamorphosis in low salinity (5), high salinity (25) and high salinity plus odor cue treatments. Megalopae metamorphosed about a week sooner in the treatment that included an adult conspecific odor cue in a low salinity environment. Hence, salinity modulates the response to the adult odor metamorphic cue in this species.