LITTORAL MICROCRUSTACEANS (CLADOCERA, COPEPODA) IN A PRAIRIE COASTAL WETLAND - SEASONAL ABUNDANCE AND COMMUNITY STRUCTURE

Seasonal species abundance and community structure of the littoral mic rocrustacean community (Cladocera, Copepoda) in two areas of Delta Mar sh were investigated over the open-water season. Cladoceran abundance in Crescent Pond, with no fish, only invertebrate predators was consid erably higher than in Blind Channel, with both fish and invertebrate p redators, and where cyclopoid copepods were the dominant microcrustace ans. In both areas, a small number of species of planktonic cladoceran s characterized the community in spring and early summer, whereas a di verse array of species of phytophilous cladocerans comprised the commu nity throughout the summer. Daphnia rosea was the most abundant specie s in the planktonic community in Crescent Pond for the first half of t he summer, and Ceriodaphnia dubia was most abundant in the last half. In contrast, no single planktonic cladoceran species was consistently most abundant in Blind Channel. The sequence of dominant phytophilous cladoceran species observed in Crescent Pond through the season was Ch ydorus sp. 2, Simocephalus vetulus, Pleuroxus denticulatus, and Ceriod aphnia dubia, and in Blind Channel, Alona circumfimbriata, Simocephalu s vetulus, and Ceriodaphnia dubia. Dominant planktonic and phytophilou s copepods in both areas were Diacyclops thomasi, Acanthocyclops verna lis, Eucyclops agilis, and Macrocyclops albidus. Canonical corresponde nce analysis revealed differences in community structure between areas of the marsh related to turbidity, phytoplankton biomass, and soluble reactive phosphorus concentration.