Zooplankton and Trophic State Relationships in Florida Lakes

Abstract

Zooplankton, including ciliated protozoans, were collected from 39 Florida lakes of widely ranging trophic state. Annual mean biomass values for different zooplankton groups were regressed against Carlson's Trophic State Index based on annual mean chlorophyll a concentration. Whereas total zooplankton biomass yielded a significant regression with increasing trophic state, microzooplankton (ciliates, rotifers, and nauplii) accounted for more of the relationship than macrozooplankton (cladocera, calanoids, and cyclopoids). Within the microzooplankton, the regression improved with decreasing body size. Macrozooplankton biomass exhibited a weak statistical relationship with lake trophic state, but the different component groups were variable in their response. The dominance within the zooplankton community shifts from macrozooplankton to microzooplankton with increasing trophic state, and the microzooplankton can constitute between 50 and 90% of the total zooplankton biomass in eutrophic lakes. Changes in zooplanktivore community structure with increasing trophic state show that whereas total fish biomass increases, dominance shifts from visually oriented predators, such as bass and bluegill, to pump filter-feeding planktivores, such as gizzard shad (Dorosoma cepedianum). While Florida zooplankton communities are similar in size structure to tropical communities, no statistically significant differences were found between empirical equations of crustacean zooplankton biomass and trophic state determined from temperate and Florida data bases.

Zooplankton assemblages in eutrophic reservoirs of the Brazilian semi-arid

“…Itans, Passagem das Traíras, and Sabugi reservoirs are dominated by cosmopolitan rotifers such as Keratella tropica, Brachionus havanensis, and K. americana, species that are generally associated with eutrophic environments dominated by cyanobacteria (Bays and Crisman, 1983;Berzins and Pjeler, 1989). According to Conde-Porcuna et al (2002), rotifers are less dependent on phytoplankton than are crustacean plankton, which would explain the higher densities observed in these reservoirs.…”

Analyzing the importance of top-down and bottom-up controls in food webs of Chinese lakes through structural equation modeling

“…Although a number of studies have found increased biomass of cladocerans, especially smallbodied individuals, with increasing lake trophic state (Bays and Crisman 1983;Pace 1986), most other studies suggest that the contribution of cladocerans to total zooplankton biomass tends to decrease with increasing TP (Jeppesen et al 2000a). Detritus and bacteria are less suitable food for cladoceran growth than at least some algae (Horton et al 1979).…”

“…Bacteria, flagellates, and detritus are also common food resources for rotifers (Sládeček 1983). It has been reported that the smaller the body size of zooplankton, the greater the dependence on bacteria as a food source (Bays and Crisman 1983). In addition, copepods are relatively selective feeders and have the capacity to graze protozoa (Sanders and Wickham 1993).…”

Experimental evidence of the effect of nutrient enrichment on the zooplankton in a Brazilian coastal lagoon

“…Higher relative importance of microzooplankton in relation to macrozooplankton is commonly observed under higher trophic conditions, especially in sub-tropical systems (Bays & Crisman, 1983;Beaver & Crisman, 1990). Within the microzooplankton, the rotifer contribution can be important in such conditions, while calanoids are generally the most affected in the macrozooplankton.…”