Temperate Rocky Reef Fishes

Abstract

This chapter considers two classes of potential metapopulation effects on temperate reef fishes: short-term demographic effects and long-term genetic effects. These can also be considered as ecological and evolutionary effects. Demographic effects are those resulting from differences in the dispersal of propagules and the resultant effects on local and regional recruitment and population dynamics. The different types of reef habitat have been described, together with the geological origins of habitats, the fish communities that inhabit them at different depths and latitudes, the present day oceanographic and climatic forces that drive variations in local demography, and the longer term forces such as glaciation and sea level change that may have shaped their genetic legacy. Since many temperate reef species have long life spans, the effects of chance on favorable recruitment events can be quite long lasting for the local populations. A single strong year class can take decades to progress through the population, first as a dominant prey item and then as a dominant predator. The presence of several age groups tends to stabilize the abundance of adults and the species composition of temperate marine communities, and the longevity and persistence of adults may also limit the risk of stochastic extinction of an allele or haplotype.