MEPS 266:195-200 (2004)  -  doi:10.3354/meps266195

Emergent and non-emergent species of harpacticoid copepods can be recognized morphologically

David Thistle*, Linda Sedlacek

Department of Oceanography, Florida State University, Tallahassee, Florida 32306-4320, USA

ABSTRACT: Emergence‹the active movement of benthic organisms into the water column and back‹has consequences for many ecological processes, e.g. benthopelagic coupling. Harpacticoid copepods are conspicuous emergers, but technical challenges have made it difficult to determine which species emerge, impeding the study of the ecology and evolution of the phenomenon. We examined data on harpacticoid emergence from 2 sandy, subtidal sites (~20 m deep) in the northern Gulf of Mexico and found 6 species that always emerged and 2 species that never emerged. An examination of the locomotor appendages revealed that the number of segments in the endopods of pereiopods 2-4 and the number of setae and spines on the distal exopod segments of pereiopods 2-4 can be used to distinguish emergers from non-emergers. We then successfully used these characters to predict the behavior of 3 additional species. Certain morphological differences may therefore allow differentiation of emergers from non-emergers.

KEY WORDS: Emergence · Harpacticoid copepods · Continental shelf · Benthopelagic coupling

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