Document: MIC-3-80-4

Stimulatory cues for molting of fiddler crab megalopae are specific to salt marshes.

JUDGE, M.L.* ¹ and N.J.O'CONNOR ²

Manhattan College Riverdale NY 10471 USA ¹
University of Massachusetts Dartmouth No. Dartmouth MA 02747 USA ²

Abstract:
Natural estuarine marsh sediments and seawater overlying marshes have been shown to stimulate in situ metamorphosis (molting) of fiddler crab (Uca pugnax) megalopae. We sought to extend our earlier work by testing whether this response is (1) restricted to intertidal salt marshes and (2) observed in another fiddler crab species inhabiting low-salinity marshes. We exposed nave, lab-reared Uca minax megalopae enclosed in plastic mesh cages to both a marsh and a river site separated by 15 m. In both habitats, megalopae were exposed to local waterborne cues without sediments. Additional marsh habitat treatments included sediment additions (freshly collected or combusted to remove organic fraction) or no marsh cues (jars of filtered seawater). Examining the megalopae after nearly three days of deployment (ca. 28 h submerged), all those exposed to natural seawater in the marsh had high rates of molting regardless of sediment type. However, megalopae in the river molted at very low rates similar to those enclosed in jars. Results indicate stimulatory waterborne cues for metamorphosis are specific to the salt marsh environment.

Keywords: life history, chemical cues, intertidal, fiddler crabs, salt marsh

This abstract is being presented at: 9:15 AM in session:
Oral Session #7: Aquatic Ecology: Shellfish to Snails.