ADAPTATIONS TO INTERTIDAL DEVELOPMENT : STUDIES ON NASSARIUS OBSOLETUS

¹ Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543

1. The extent to which reproduction of the intertidal mud snail, Nassarius obsoletus, is adapted to the intertidal environment was examined in an attempt to understand the adaptive significance of egg capsules in the life history.

2. Contrary to expectation, laboratory studies on desiccation tolerance of encapsulated embryos and rates of water loss from egg capsules failed to reveal any adaptation to intertidal development. Fifteen minutes of desiccation over CaSO₄ caused as much as 20% mortality of N. obsoletus embryos, and daily 0.5 hr exposures to 75% relative humidity killed 17.5% of the embryos. Egg capsules of N. obsoletus and those of the subtidal N. trivittatus lost water at essentially equal rates.

3. Protection of the developing embryos seems dependent upon adult behavior. Adults tend to deposit egg capsules into microenvironments where the embryos are probably spared exposure to desiccation stress at low tide. Fewer than 8% of the capsules examined at Quissett Harbor, Massachusetts, were fully exposed to desiccation.

This article has been cited by other articles:

				R. D. Podolsky Integrating Development and Environment to Model Reproductive Performance in Natural Populations of an Intertidal Gastropod Integr. Comp. Biol., July 1, 2003; 43(3): 450 - 458. [Abstract] [Full Text] [PDF]