MEPS 528:235-243 (2015)  -  DOI: https://doi.org/10.3354/meps11284

ABSTRACT: Desiccation stress is a major limiting factor for many organisms in the intertidal zone. Sessile mollusks often reduce water loss by isolating themselves from the external environment upon aerial exposure, which can result in other stressful conditions within their sealed mantle cavity. Interestingly, some intertidal animals willfully expose their tissues to the air when emersed (‘gaping,’ ‘mushrooming,’ or ‘lifting’ behavior). This basic behavior—and the desiccation tolerance—of the cosmopolitan gastropod Crepidula fornicata have not been thoroughly investigated. We found that individuals of C. fornicata almost always have their shells lifted off of the substrate when submerged, but that they also perform this lifting behavior periodically when exposed to air. The lifting behavior was costly, however, as air-exposed juveniles that were free to lift lost significantly more water than those that were artificially clamped to the substrate. We found no measurable difference in desiccation tolerance between intertidal and subtidal adults, which all survived aerial exposures of up to 10 h. In contrast, most small juvenile C. fornicata died following only 2 to 6 h of exposure, after losing between 38.5 and 75.5% of their tissue water. Because juveniles lost water so quickly, desiccation stress may be an important limiting factor for C. fornicata, unless juveniles can move to wet areas when exposed to air until they are large enough to withstand longer periods of aerial exposure.

KEY WORDS: Desiccation · Lifting behavior · Gaping · Intertidal · Crepidula