AN ECOLOGICAL IDENTIFICATION SYSTEM FOR MARINE PLANKTONIC COPEPODS

An ecological identification system, an alphanumeric method, is developed for zooplankton community analysis. Using current taxonomic knowledge, organisms are identified to the genus level. All individuals of a genus are further subgrouped into immature, adult males, and adult females. Total lengths of individual copepods are then used to separate different size populations within each of these subgroups. These size groups are coded numerically. This method, named generic size group (GSG) identification, was applied to an analysis of two copepod communities from the Carolinian continental shelf of the southeastern United States. Results of this analysis show that the GSG method can separate most copepods into species without the use of classical taxonomy beyond genus identification. Also, subpopulations within a life stage are separated.;Using length information obtained by the GSG method, an information index of length, I'( ), is proposed here based on the formula.;(DIAGRAM, TABLE OR GRAPHIC OMITTED...PLEASE SEE DAI).;where s is the number of taxa, N(,i) is the number of individuals, and (,i) is the mean length. This index may be useful for monitoring purposes because it is an expression of a functional aspect of the community whereas other diversity indices treat only relative abundance. A comparison of diversity indices, particularly Simpson' index, Shannon's index, and I'( ), is made between communities analyzed by taxonomic species and by GSG.;Many copepod species from the study areas have displayed a significant sexual size dimorphism and a seasonal mean size difference. A high correlation exists between mean length and the log of dry-weight of GSGs within each species. This suggests that a reasonable biomass estimate (dry weight) of a community is possible by using the GSG identification method.;A sequentially numbered taxonomic key is developed for generic identification of North Atlantic copepods. This sequential key is shorter and easier to understand than a conventional dichotomous key.