BIODIVERSITY OF THE PELAGIC OCEAN

This paper reviews knowledge of biodiversity in open ocean pelagic communities and discusses the possible causal factors for the patterns. The oceanic pelagic ecosystem is by far the largest on Earth and, although locally its assemblages may be as rich as many terrestrial ecosystems, its global diversity (at both a species and an ecosystem level) is low. There are latitudinal trends in pelagic species diversity similar to those in many terrestrial taxa. High species richness in the oceans, however, tends to be associated with regions of low productivity that lack strong seasonality in the production cycle. The richest zones occur at the boundaries between different types of oceanic water where different faunas are mixed together, but the geographical locations of these boundaries are unstable and shift seasonally by hundreds of kilometers. If high diversity is emphasized in the development of protocols for conservation, then not only will the oceans receive low priority in conservation and resource management, but the regions most important in terms of process will also be overlooked. The scales of oceanic systems are so large that the methodologies developed for terrestrial conservation and resource management are inapplicable Biodiversity may be regarded as the principal criterion for developing management strategies, yet the links (if any) between the ecological processes in the ocean that play such an important role in global homeostasis remain poorly characterized. The basis for a predictive understanding of the interaction between diversity and ecological process can be greatly enhanced relatively inexpensively by systematically collating existing data and working up extant collections of material