Large-scale spatial heterogeneity of macrozooplankton in Lake of Geneva

Abstract

Spatial distribution of macrozooplankton was studied during spring in Lake of Geneva to evaluate the influence of abiotic (water temperature and stability, nutrients) and biotic (bacteria, chlorophyll a, fish biomass) factors on macrozooplankton distribution. Mapping and spatial analyses revealed that abiotic factors, as well as crustacean abundances, were structured along a gradient in the great lake basin. Chlorophyll a biomass, bacteria density, cyclopoid abundance, and fish biomass showed more patchy or inshore-offshore distribution patterns. Using canonical analyses, we determined the relative contribution of the spatial and environmental factors to the distribution of macrozooplankton species and of trophic groups based on herbivory and omnivory/carnivory. The distribution of macrozooplankton can be explained by small-scale variations and lake gradients in abiotic and biotic factors, with a dominant contribution of the abiotic factors. Water temperature and stability, as well as ammonium, are the main factors related to macrozooplankton distribution in Lake of Geneva during spring. Chlorophyll a biomass was also related to the distribution of cyclopoids. The canonical models explained 35-72% of the variance in the distribution of total crustaceans, species, and trophic groups. However, 28-65% of the macrozooplankton variance remained unexplained, which may be due to fine-scale variations in other environmental factors.Résumé : La distribution spatiale du macrozooplancton dans le Lac Léman (ou Lac de Genève) a été étudiée au printemps pour déterminer l'influence des facteurs abiotiques (température et stabilité de la colonne d'eau, nutriments) et biotiques (bactéries, chlorophylle a, biomasse des poissons) sur la distribution du macrozooplancton. La cartographie et l'analyse spatiale ont révélé que les facteurs abiotiques, ainsi que l'abondance des crustacés, étaient structurés selon un gradient dans le grand lac. La biomasse en chlorophylle a, la densité des bactéries, l'abondance des cyclopoïdes et les biomasses de poissons présentaient des patrons de distribution plus agrégés ou des gradients rive-large. À l'aide d'analyses canoniques, nous avons évalué l'influence relative des facteurs environnementaux et des structures spatiales dans la distribution des espèces de macrozooplancton et des groupes trophiques basés sur les catégories d'herbivores et d'omnivores/carnivores. La distribution du macrozooplancton s'explique à la fois par les variations locales à petite échelle et les gradients à grande échelle des facteurs abiotiques et biotiques, avec une contribution plus importante des facteurs abiotiques. La température et la stabilité de la masse d'eau ainsi que les concentrations en ammoniaque sont les principaux facteurs reliés à la distribution spatiale du macrozooplancton dans le grand basin du Lac de Genève. La biomasse en chlorophylle a est aussi reliée à la répartition des cyclopoïdes. Les modèles canoniques expliquent 35 à 72% de la variabilité dans la distribution des crustacés totaux, des espèces...

Assessing spatial and temporal patchiness of the autotrophic ciliate Myrionecta rubra: a case study in a coastal lagoon

“…8) emerged after processing a large number of conditional simulations, used for the first time to assess patches at the large scale. These patches are likely related to abiotic processes associated to basin morphometry and size, wind regime, and current patterns (Pinel-Alloul et al 1999); furthermore, fresh-and marine water influx may generate patchiness in this lagoon; seasonal variations in allochthonous nutrient inputs will stimulate maximal growth of M. rubra. The high nutrient content of the river discharge in this area, together with the restrictive northwards mixing of the waters from the Nexpa River (Mee 1977), may explain the localized large-scale patch in the western lagoon (Fig.…”

“…6). At this scale, besides the dissipation of larger patches, some abiotic generative processes may include wind current patterns and downwind accumulation (Pinel-Alloul et al 1999). Furthermore, migration and growth may be biotic factors contributing to patch formation at this scale (Crawford & Lindholm 1997).…”

Quantitative analysis of the importance of wind‐induced circulation for the spatial structuring of planktonic populations

“…Recent developments in the analysis of spatially referenced ecological data make this possible (Legendre et al, 2002), provided a suitable tracer of lake physical structure is available. Many previous studies actually reported the results of surveys that took many hours or days to complete (Kalikhman, 1999;Pinel-Alloul et al, 1999), yet spatial pattern in lacustrine environments shows a high degree of temporal variability. Dynamic changes in the physical structure of the pelagic environment cause distribution patterns of planktonic organisms to vary over time (George & Edwards, 1976;Jones et al, 1995;Ragotzkie & Bryson, 1953).…”

Temporal and Spatial Distributions of Rotifers in Xiangxi Bay of the Three Gorges Reservoir, China

“…Zooplankton spatial distributions are as heterogeneous as those of terrestrial and aquatic plants and animals (FERNÁNDEZ-ROSADO and LUCENA, 2001). Now, it is a well-known phenomenon (SEDA and DEVETTER, 2000) and has been shown to be an ecologically important feature of freshwater ecosystems (PINEL-ALLOUL et al, 1999). The structure and composition of organisms and the spatial pattern of a community are of crucial importance for understanding ecosystem functioning (ROSENZWEIG, 1991;ROMARE et al, 2003) because they can affect ecosystem processes, functioning and stability (MAESTRE et al, 2005 eutrophication, which can strongly affect numbers, standing crops, population dynamics, production and community structure of zooplankton (CAJANDER, 1983).…”