The vertical and temporal distribution of metazooplankton in the small hypertrophic, strongly stratified, temperate Lake Verevi (Estonia) was studied during 1998-2001. The zooplankton of Lake Verevi is characteristic of hypertrophic lakes, with a small number of dominant species, rotifers being the main ones, and juveniles prevailing among copepods. In 1999-2001, the average abundance of metazooplankton in the lake was 1570 · 10 3 ind m )3 ; in the epilimnion 2320 · 10 3 ind m )3 , in the metalimnion 2178 · 10 3 ind m )3 , and in the hypolimnion 237 · 10 3 ind m )3 . The average biomass of metazooplankton was 1.75 g m )3 ; in the epi-, meta-and hypolimnion, accordingly, 2.16, 2.85 and 0.26 g m )3 . The highest abundances -19,136 · 10 3 ind m )3 and 12,008 · 10 3 ind m )3 -were registered in the lower half of the metalimnion in 24 May and 5 June 2001, respectively. Rotifer Keratella cochlearis f. typica (Gosse, 1851) was the dominating species in abundance. In biomass, Asplanchna priodonta Gosse, 1850, among the rotifers, and Eudiaptomus graciloides (Lilljeborg, 1888), among the copepods, dominated. According to the data from 2000-2001, the abundance and biomass of both copepods and rotifers were highest in spring. Zooplankton was scarce in the hypolimnion, and no peaks were observed there. During the summers of 1998 and 1999, when thermal stratification was particularly strong, zooplankton was the most abundant in the upper half of the metalimnion, and a distinct peak of biomass occurred in the second fourth of the metalimnion. Probably, the main factors affecting the vertical distribution of zooplankton in L. Verevi are fish, Chaoborus larvae, and chemocline, while food, like phytoplankton, composition and abundance may affect more the seasonal development of zooplankton.

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Corer samples of zoobenthos were collected in 20 coastal water bodies of western Estonia including 2 inner parts of bays of the Baltic Sea, 5 lagoons weakly connected with the sea, and 13 freshwater lakes in August 2004. Reigi laht, an open bay, was the only site where brackishwater taxa dominated; in the same bay, eumeiobenthic small Nematoda were very abundant. At all other sites, the bulk of meiobenthos was formed of small, pseudomeiobenthic individuals of Chironomidae and Oligochaeta, while eumeiobenthos, consisting here mainly of Nematoda and Ostracoda, was outnumbered by the former. The near-bottom planktic Cladocera and Copepoda were also common. Freshwater taxa dominated in all lagoons and lakes, with scarce brackish-water species accompanying them in the lagoons as well as in some lakes. The abundance and biomass of pseudoand eumeiobenthos, as well as of planktic crustaceans, were higher in the lagoons than in the freshwater lakes.