Vol. 43 No. 2, 2004

Deep-sea Benthopelagic Calanoid Copepods and their Colonization of the Near-bottom Environment

Janet M. Bradford-Grieve

National Institute of Water and Atmospheric Research, P.O. Box 14901, Kilbirnie, Wellington 6001, New Zealand

Janet M. Bradford-Grieve (2004) We are still in a discovery phase with respect to the deep-sea benthopelagic fauna and its ecology. New species are being described every year, and our knowledge of the physical and sedimentary environments of the benthic boundary layer is currently being extensively researched by a number of groups. Deep-sea, strictly benthopelagic copepod populations (composed mainly of Calanoida) differ in species composition from those in shallow and shelf waters and probably all represent reinvasions of the benthopelagic environment from the water column. The reasons for this difference are explored, including the possible evolutionary paths of organisms that live in this environment, and the physical conditions in which they live. Oxygen availability was probably a limiting environmental factor in geological time for benthopelagic calanoids. The low oxygen requirements and low weight-specific respiration rates of benthopelagic copepods are suggestive of a Permian reinvasion of the deep benthopelagic environment. That is, they were selected for low oxygen demand by the timing of their reinvasion of the deep benthopelagic environment. It is possible that these hypotheses may be testable using genetic information in the near future.

Key words: Arietelloidea, Clausocalanoidea, Paleoenvironment, Evolution, Colonization.

*Correspondence: Tel: 64-4-3860300. Fax: 64-4-3862153. E-mail: j.grieve@niwa.co.nz