Catastrophe, Extinction, and Species Diversity: A Rocky Intertidal Example

Abstract

Geographically widespread episodes of catastrophic mortality affect local species diversity. Sea ice has been a frequent catastrophic mortality agent on rocky shores in New England during the historical past. Empirical demographic data and the historical record of winters with sea ice were used in a population projection model of intertidal barnacles. Projections indicate that animals that live exclusively in the zone affected by ice would have become extinct under the conditions of sea ice disturbance that have existed in New England during the past 300 yr. This may explain the absence from New England of abundant, large, long—lived species with delayed reproduction that are restricted to the mid to low intertidal zone. Such species are common elsewhere in the world on shores unaffected by ice. Given the cyclic nature of the postglacial climate, global patterns of species richness may be influenced by climatically induced extinction pressures of this kind.