Seasonal succession and vertical distribution of zooplankton in Lake Hayes and Lake Johnson

Abstract

Seasonal variations in the species composition, abundance, biomass, and vertical distribution of zooplankton in two eutrophic, warm-monomictic lakes are described for the period December 1969 to February 1972. In Lake Hayes, Boeckella dilatata was the dominant crustacean and Ceriodaphnia dubia was subdominant. Lake Johnson was dominated by Ceriodaphnia and Bosmina meridionalis and Boeckella were subdominant. Daphnia were common in spring in Lake Hayes, but very rare in Lake Johnson. Chydorus and Asplanchna appeared in summer in both lakes. Zooplankton were slightly more abundant in both lakes in 1971 than in 1970; the annual mean was 1.7 times higher in Lake Johnson than in Lake Hayes in both years. Biomass was highest in spring. In Lake Hayes it ranged from 0.7 to 4.6 g.m -2 dry weight; in Lake Johnson it fluctuated in 1971 from 0.3 g.m -2 in March to 7.4 g.m -2 in November. Animals occurred at all depths during holomixis, but were nearer the surface during stratification. Vertical distribution was often bimodal, with a peak in the metalimnion and a second, smaller one in the epilimnion.In Lake Johnson a stratum of anoxic water developed in the metalimnion each summer. In 1971 Boeckella were confined to the oxygenated hypolimnetic water below this zone, and almost disappeared from the lake as the hypolimnion became anoxic in late summer. In 1970, when they were largely confined to the epilimnion, the population increased over the same period. Ceriodaphnia had a similar vertical distribution to Boeckella in 1971, but did not decline in numbers, perhaps because of reproduction by the small number of animals remaining in the epilimnion. It is postulated that an increase in the cyclopoid population of the oxygenated hypolimnion was the result of recruitment, either from the benthic region or by migration from the epilimnion through the anoxic layer.Chydorus has appeared in the plankton of Lake Hayes since 1953, and cyclopoids have become more abundant. These changes are consistent with other evidence that the lake is becoming more eutrophic.

Evaluation of vertical and horizontal changes in community structure of zooplankton in a deep dam lake

“…Furthermore, temperature and food in the epilimnion are useful for the zooplankton in this region, but the highest fish predation is seen at this layer, as well. Trade-offs exist between feeding and predator avoidance (Burns and Mitchell, 1980;Masson et al, 2001;Andersen et al, 2004;Ignoffo et al, 2005). The composition and dynamics of the zooplankton community are affected by interspecies competition and selective predation pressures.…”

Aspects of the biology and taxonomy ofPiona exiguaViets, a predatory freshwater mite

“…Lake Hayes is a productive lake with significant populations of planktonic Fiona and Cladocera (Burns & Mitchell 1980). The major collection methods were oblique or vertical tows with 2 conical nets (one 1.6 m long Wisconsin-type net, aperture size = 0.1 mm; the other 0.75 m long, aperture size=0.03 mm) from a small boat A search for larvae ectoparasitic upon chironomid imagines at Lake Hayes was conducted on 3 occasions when insect emergence was high.…”

“…1984). Habitats rangein trophic status from the oligotrophic Lake Lyndon (Flint 1975;Spencer 1978), through moderately productive lakes such as Lakes Sarah or Grasmere (Timms 1983) and Lake Rerewhakaaitu (Chapman et al 1981), to eutrophic Lake Johnson (Burns & Mitchell 1980) and Lake Ngahewa (Forsyth & McColl 1975). Piona is notably absent from Lake Taupo (Forsyth & McCallum 1980).…”

Desmids (Chlorophyta), including two new species and three new varieties, in two swamps, a lake, and a tarn in the South Island of New Zealand

“…Earlier he had identified algae in four lakes in the South Island (Flint 1938(Flint ,1979. Cassie (1974) recorded 23 taxa of desmids in Lake Rotorua, and, in contrast, Burns & Mitchell (1974) found only 6 desmids in the eutrophic Lake Hayes.…”