Factors Controlling the Planktonic Community in the Shallow‐Lake of Créteil, France

Abstract

A two‐year study on the seasonal pattern of plankton was performed in a shallow, polymictic, eutrophic lake. Autogenic successions typical of stratified lakes did not occur. Only small edible algae developed throughout the two years and Cyanophyceae rarely appeared, and did not bloom. Algal sequences depended on wind‐induced periodic mixing of water. The seasonal pattern of Rotifers varied greatly from year to year and some species depended on sporadic increases of algae. In contrast, the seasonal pattern of microcrustacea was more regular. Resting stages played an important role in zooplankton development in this variable environment. Successful fish reproduction depended a great deal on climatic conditions. The changes from year to year in predation pressure from young fish appeared to be an important factor controlling zoo‐plankton structure.

Effects of food-web structure on the quantity and the elemental quality of sedimenting material in shallow lakes

“…Contrary to these studies, we found no significant difference in mean algal cell biovolume between the two treatments. This result was probably due to the strong dominance of small algal species in Lake Créteil (Lacroix et al, 1989;Bertolo et al, 2000). a C/N molar ratios, b C/P molar ratios, and c N/P molar ratios.…”

“…This study took place in the meso-to eutrophic (range of 2005 summer chlorophyll concentration: 3-42 lg chl a l -1 ) Lake Créteil (48°46 0 37 00 N, 2°26 0 47 00 E), a small (42 ha), shallow (mean depth: 4 m, maximal depth: 6 m) sand-pit lake (siliceous parent rock) situated 15 km southeast of Paris, France (for more information on this lake, see Lacroix et al, 1989;Bertolo et al, 1999). Eight large enclosures, made of translucent polyethylene reinforced with nylon mesh, were suspended 25 cm above the lake surface on a floating rectangular pontoon.…”

Food-web structure and functioning of temperate and tropical lakes: A stoichiometric viewpoint

“…However, differences between temperate and tropical systems were weak. Seston N:P ratio was rather low in temperate enclosures when considering the low SRP concentrations, typical of Lake Cre´teil during summer (Lacroix et al, 1989). Elrifi and Turpin (1985) showed that cellular requirements increase more quickly for P than for N with growth rate, thus diminishing the N: P ratio of algal cells (see also Agren, 2004).…”

Ecological interactions in a shallow sand-pit lake (Lake Créteil, Parisian Basin, France): a modelling approach

“…Only small species of Chlorophyceae, centric diatoms and Cryptophyceae thus developed forming pulses or peaks initiated in summer by wind perturbations. Moreover, increase in phytoplankton biomass was frequently followed by an increase in zooplankton populations (Lacroix et al, 1989), which in turn contrib-uted to algal decline (Garnier & Lescher-Moutou6, 1984). As a consequence, the high frequency of seasonal fluctuations is not simulated by the present model, and also because the complexity of zooplankton biology is not taken into account.…”

“…The whole programme included the study of hydrology (Ches-t6rikoff etal., 1981;Chesttrikoff & Chevreuil, 1987), of physiological processes at a microscopic scale (Garnier, 1989;Garnier & Benest, 1990Mourelatos et al, 1989;Garnier & Mourelatos, 1991), of seasonal successions and interactions of planktonic communities (Garnier & Lescher-Moutou6, 1984;Lescher-Moutou6 et al, 1985;Lacroix et al, 1989) and of fish dynamics (Boat, 1981;Gerdeaux, 1986). The large set of data available concerning this system is well suited to serve as the basis for the establishment of a mathematical model intended to represent, in an idealized way, the major features of the ecological functioning of sand-pit lakes.…”