What to do when there is nothing to do: The ecology of Jamaican intertidal Littorinidae (Gastropoda: Prosobranchia) in repose

Abstract

The littorine gastropods Cenchritis muricatus, Nodilittorina mespillum, N. angustior, N. dilatata, N. riisei, N. ziczac and Tectarius antonii from a natural limestone platform on the north coast of Jamaica were evaluated according to several ecological parameters in an effort to define their respective niches on this shore. Distributions along transects perpendicular to the shore demonstrated that distance from the sea is one, albeit not always consistent, ecological criterion which serves to delineate these species. N. riisei generally occupies that region of the shore frequently wetted by wave splash, N. mespillum is usually found within frequently refreshed tidepools and C. muricatus always occupies the highest regions of the shore most distant from the sea. There is, however, considerable overlap between these and other species and, along much of the rock platform, N. angustior, N. dilatata, T. antonii and C. muricatus are sympatric. N. dilatata has the broadest range on this low profile limestone platform. A comparison of body temperatures and substratum temperatures taken from adjacent rock surfaces revealed that the body temperatures of T. antonii generally reflect that of the ambient environment. On the other hand, C. muricatus, N. dilatata, N. riisei and N. angustior seem to thermoregulate, maintaining body temperatures above ambient at temperatures below 29°C and below ambient at temperatures above 33°C. Data were also compiled for most species with respect to resting posture (whether hanging suspended or resting aperture-down), resting site (whether within the shelter of a crevice or upon an exposed rock surface), shell orientation and the relative frequency (presence or absence) of a mucous holdfast. Size-frequency analyses indicate that N. riisei and N. angustior re-populate the shore from the meroplankton at least sometime between January and March. © 1998 Kluwer Academic Publishers.