Diel Vertical Migration by Copepoda, Cladocera, and Rotifera in Lake Texoma (Oklahoma-Texas)

The functional role of animals in marine and freshwater systems is as diverse as the many species occupying these unique habitats. Physical, chemical and biological parameters affect the behavior and distribution of aquatic organisms and influence the overall productivity of aquatic ecosystems. In planktonic communities, diel vertical migration (DVM) is a behavioral response to the physico-chemical and biological variables within oceans and lakes. There are several theories of DVM, which include predator avoidance, escape from harmful ultraviolet light, migrating to optimal temperature depths and migrating to food-rich zones. Three major taxonomic groups dominate zooplankton communities: phylum Rotifera, and two subclasses of crustaceans, the Cladocera and Copepoda. In this study, I tested DVM on these three groups of zooplankton in order to see if there is a relationship between DVM and the solar and lunar photoperiods. Copepods dominated the samples taken in all depths and sampling periods. Rotifers and cladocerans made up one fourth of the sampling effort. Cladocerans showed a significant migration towards the surface starting around sunset and had a maximum concentration right before midnight. Both copepods and rotifers exhibited significant migration to surface waters, beginning around local noon. Rotifer concentrations at the surface were greatest at midnight; however, copepod concentrations at the surface peaked at sunset. Relationships between surface migration and time of day was strong for all three groups. Correlation with vertical migration and apparent lunar position showed a strong association with copepods and rotifers. Keywords: Diel vertical migration, zooplankton, predator avoidance theory, euphotic zone, photosynthetically available radiation, day-night photoperiod. DOI : 10.7176/JEES/14-5-02 Publication date : September 30th 2024