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The World of Protozoa, Rotifera, Nematoda and Oligochaeta

Ref ID : 1589

Gary W. Hunt and Shih Ming Chein; Seasonal distribution, composition and abundance of the planktonic Ciliata and Testacea of Cayuga Lake. Hydrobiologia 98:257-266, 1983

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The planktonic protozoans (Ciliata and Testacea) of Cayuga Lake were studied from September 1974 through July 1975. Monthly collections were taken at four depths (surface, 15, 31 and 92 m) at each of seven stations along the 125 m depth contour. All samples were collected with a 6-liter Van Dorn bottle sampler. Densities and biomass were determined for total protozoans and total zooplankton at each depth on each sampling date. Temperature profiles at one-meter intervals were also determined on or within a few days of the zooplankton sampling. The vertical distribution of the total protozoans was directly related to temperature; maximum densities corresponded to high summer surface temperatures. Dominant protozoan taxa included Didinium nasutum, Stokesia vernalis, Codonella cratera, Strobilidium gyrans, Strobilidium sp., Strombidium viride, Paradileptus canellai, Difflugia limnetica, and unidentified ciliates belonging to the families Halteriidae, Holophryidae, Epistylidae, and Vorticellidae. Protozoans composed 69% or more of the total zooplankton density on one of eleven dates. Protozoan dominance was most evident during winter and spring, corresponding to the ear absence of rotifers and microcrustaceans. Protozoans accounted for 30% or more of the zooplankton biomass from April through June, reaching 47% in May.