The relative importance of protozoans, rotifers, and crustaceans in a freshwater zooplankton community1

Abstract

A complete analysis of the macro-and microzooplankton of a warm monomictic lake indicates that Protozoa dominate the community numerically.

Unexpected increases in rotifer resting egg abundances during the period of contamination of Lake Orta

“…Monogonont rotifers represent a large fraction of plankton diversity in lakes (Pace and Orcutt, 1981;Visconti et al, 2008), and they are commonly responsible for a springsummer zooplankton population maximum (Orcutt and Pace, 1984;van Dijk and van Zanten, 1995;Yoshida et al, 2001). In the present study, we quantified changes in richness, diversity and abundance of rotifer resting eggs N o n -c o m m e r c i a l u s e o n l y (RREs) in a sediment core of Lake Orta, Italy.…”

Sampling and preservation methods for the quantitative enumeration of microzooplankton

“…The preservatives compared were acid Lugol's iodine (1% final concentration solution), glutaraldehyde (2%), and formalin (2%); a fourth set of subsamples were fixed with 2 drops of bromophenol blue and preserved with 10 ml of saturated HgCl2 solution. The concentrations of preservatives were the same as those used in previous studies (Pace & Orcutt 1981;Rassoulzadegan et al 1988;Chang 1990;Mazumderetal. 1990).…”

“…The most common fixatives used in planktonic studies are glutaraldehyde (Rassoulzadegan et al 1988), formaldehyde (Mazumder et al 1990), mercuric chloride (Pace & Orcutt 1981), and Lugol's iodine (Chang 1990). Aldehydes are also used for terminating ciliate grazing experiments and for fixing microflagellates (Sanders et al 1989).…”

“…Phytoplankton are generally enumerated from small volumes of water collected with water bottles and either filtered onto a filter (Dosier & Richerson 1975) or settled in a chamber (Utermohl 1958). Zooplankton are generally collected by vertical net hauls with 20-250 nm mesh nets (James 1989;Madoni 1990), using plankton traps (Mazumder et al 1990), pumping and collecting on mesh screens (Beers & Stewart 1971), and in water bottles (Pace & Orcutt 1981;Beaver & Crisman 1982). Results of microzooplankton enumerations of samples from similar water masses can differ several orders of magnitude, depending on sampling technique (cf.…”

The effect of attached vorticellids on the buoyancy of the colonial cyanobacteriumAnabaena lemmermannii

“…Species of the peritrichs Vorticella and Pseudovorticella (Warren, 1986(Warren, , 1987, which concern us here, occur on a wide range of planktonic cyanobacteria. In addition to all the aforementioned genera they have also been reported from Aphanocapsa, Gloeotrichia, Lyngbya, Nostoc and Rivularia (Kahl, 1935;Davis, 1973;Pace & Orcutt, 1981;Kerr, 1983;Pratt & Rosen, 1983;Canter, Heaney &Lund, 1990 Both Kerr (1983) and Pratt & Rosen (1983) record the attachment of several species of Vorticella to a variety of cyanobacteria. Kerr (1983) noticed that Nostoc sp.…”