Phytoplankton–zooplankton seasonal timing and the ‘clear‐water phase’ in some English lakes

Abstract

SUMMARY 1. An examination is made of the relative seasonal timing of the postwinter increase of phytoplankton and zooplankton populations in four English lake basins. It centres upon weekly sampling over 20 years and rough counts of larger Crustacea, as copepods and cladocerans, from filtered samples that were used for chlorophyll a (Chl) estimation. 2. Typically, a spring maximum of phytoplankton, dominated by diatoms and earlier in the shallower lakes, is accompanied or followed by a maximum of copepods and then one of cladocerans dominated by the Daphnia hyalina–galeata complex. Regarding timing, the maximum of copepods has no apparent relation with phytoplankton abundance (Chl). The maximum of cladocerans appears to be largely independent of variation in the phytoplankton maximum, but is generally associated with a minimum in Chl. Evidence for some direct causality in this inverse correlation after the spring phytoplankton maximum is best displayed by the shallow Esthwaite Water in which the peaks of Chl and cladocerans are separated further than in the deep Windermere basins where phytoplankton growth is delayed. In Esthwaite Water, and possibly often in Windermere, a principal minimum in Chl is ascribable to grazing by Daphnia. 3. The typical inverse relationship of Chl and cladocerans is lost in some years when relatively inedible large phytoplankters (e.g. colonial chrysomonads, filamentous cyanophytes) are abundant and Chl minima are less pronounced, although maxima of cladocerans still occur. Conversely, available edible phytoplankters include various small forms grouped as μ‐algae and Cryptomonas spp.; their probable depletions by Daphnia appear to be sequential and may limit the latter's maxima, whose inception is temperature‐dependent. 4. The spring–summer maxima of cladocerans and minima of Chl are generally coincident with a main seasonal maximum of Secchi disc transparency and light penetration – to which removal of non‐phytoplankton particles by filtering cladocerans may contribute.

Impacts of two biomanipulation fishes stocked in a large pen on the plankton abundance and water quality during a period of phytoplankton seasonal succession

“…It is well known that a clear water phase occurs with a high density of Daphnia (Kasprzak et al, 2002;Talling, 2003). However, this was not the case in our study.…”

“…Large-sized zooplankton are known to be highly efficient grazers and may be more important for the improvement of water quality. A 'clear water phase' in early summer may be attributed to the grazing of large crustacean zooplankton (Talling, 2003). Fish kills or low fish recruitment may lead to high grazing pressure on phytoplankton and clear water conditions throughout the summer (Hosper and Meijer, 1993;Jeppesen et al, 2004).…”

Phytoplankton response to fish-induced environmental changes in a temperate shallow pond-type lake

“…In 2003In -2009 Agnieszka Napiórkowska-Krzebietke . brama, H. molitrix, H. nobilis, R. rutilus, and E. lucius, the percentage share of which in the total catches ranged from 19% to 26%.…”

“…The general trend in the seasonal development of phytoplankton includes one, two, or even more, similarly or differently sized peaks of biomass (PEG model;Sommer et al 1986,increasing grazing associated with late spring zooplankton biomass maximums can occur along with phytoplankton maximums at the end of spring in eutrophic lakes. Thus, such temporal shifts in phytoplankton-zooplankton relations facilitate the occurrence of clear-water state (Talling 2003, Ttnno et al 2003, Effler et al 2015, which may not appear in hypertrophic lakes.…”

Patterning Zooplankton Communities in Accordance with Annual Climatic Conditions in a Regulated River System (Nakdong River, South Korea)

“…In addition, the composition and structure of phytoplankton is affected by zooplankton biomass and diversity (GOSSELAIN et al, 1998). It is already well known that the clear-water phase in freshwaters can be affected by zooplankton (ARNDT and NIXDORF, 1991;TALLING, 2003). Finally, meteorological condition such as rainfall can lead to high flushing rate which generates 'washout' of zooplankton (BROOK and WOODWARD, 1956;RICHARDSON, 1991).…”