CYCLOPIDAE DES EAUX SOUTERRAINESDE L'ILE DE MAJORQUE (ESPAGNE)

International audienc

Cyclopidae des eaux souterraines de Portugal et de l’île de Majorque (Crustacea, Copepoda)

Eight species of Cyclopidae (Copepoda) are recorded from continental groundwaters of the Iberian peninsula and Mallorca. The six species from Portugal constitute the first records of subterranean Cyclopidae from that country. Thermocyclops oblongatus is new to the Iberian peninsula, and the range of Metacyclops subdolus is extended westward to Mallorca

Cyclopidae des eaux souterraines de Portugal et de l’île de Majorque (Crustacea, Copepoda)

Eight species of Cyclopidae (Copepoda) are recorded from continental groundwaters of the Iberian peninsula and Mallorca. The six species from Portugal constitute the first records of subterranean Cyclopidae from that country. Thermocyclops oblongatus is new to the Iberian peninsula, and the range of Metacyclops subdolus is extended westward to Mallorca

CYCLOPIDAE DES EAUX SOUTERRAINESDE L'ILE DE MAJORQUE (ESPAGNE)

International audienc

Sur le nombre de stades naupliens chez Eucyclops serrulatus

L'étude morphologique et biométrique du développement postembryonnaire d'Eucyclops serrulatus (Fischer) a permis de montrer la présence de six stades naupliens chez cette espèce. Six catégories différentes d'exuvies ont été recueillies dans les élevages

Diapause des Cyclopides d'un écosystème lacustre peu profond (Lac de Créteil, France)

La diapause des Cyclopides pélagiques d'un lac tempéré peu profond (Créteil, France) a été étudiée sur un cycle annuel. Une dormance estivale affecte les copépodites IV de Cyclops vicinus (avril-mai à février) et de Diacyclops bicuspidatus (mars à novembre) ; une diapause hivernale est observée chez les copépodites IV de Thermocyclops crassus et chez les subadultes de Thermocyclops oithonoides (septembre à avril). Quelques subadultes de Th. oithonoides ont un arrêt de développement sans pénétration dans le sédiment (diapause active). La biomasse moyenne de la fraction diapausante égale 36 % (15 % à 80 %) de la biomasse totale des Cyclopides pendant la période d'étude. Les effectifs benthiques, compris entre 27 000 ind. m-2 et 350 000 ind. m-2, représentent un potentiel de recolonisation du domaine pélagique de 6 ind. l-1 à 78 ind. l-1. Alors que la diapause hivernale de Th. oithonoides et de Th. crassus est probablement une adaptation à des conditions climatiques défavorables, la diapause estivale de C. vicinus serait une stratégie adaptative d'évitement de la prédation

Gelyella droguei n. g., n. sp., curieux Harpacticide des eaux souterraines continentales de la nouvelle famille des Gelyellidae

Description d'une nouvelle espèce découverte dans les eaux souterraines karstiques continentales de la région de Montpellier (France). De nombreux caractères originaux tels la structure primitive des appendices céphaliques, la disparition de la P4 et de la P5, la réduction de la segmentation des exopodites et des endopodites des P1 à P3, nous ont conduits à créer une famille et un genre nouveaux

Biomass and production of plankton in shallow and deep lakes : are there general patterns ?

Empirical models were established, which link the biomasses or productions of the successive planktonic trophic levels in lakes of different depth and trophic status. Published data on 56 lakes were analysed, using both least-square and reduced-major-axis regressions. Reduced-major-axes regression technique was used in order to take into account variability due to both bottom-up and top-down forces. In shallow lakes, the energy transfer efficiency between phytoplankton and zooplankton decreases with increasing trophy. An inverse tendency appears in deep lakes. However, when considering only the oligo- and mesotrophic temperate lakes, the mean primary and secondary productivities per unit of area are about the same in shallow and in deep sites. On the other hand, shallow water bodies are characterized by a smaller mean size of the crustacean species, a lower mean biomass of zooplankton and a higher P zoo/B zoo ratio than deep lakes, probably as a response to the predation by fish. While the consumers seem to have a strong influence on the size structure and biomass of plankton, the energy flows between the trophic levels could be largely controlled by bottom-up forces

Effects of fomesafen, alone and in combination with an adjuvant, on planktonic communities in freshwater outdoor pond mesocosms.

International audienceEcotoxicological effects of the diphenyl ether herbicide fomesafen, applied alone or in combination with the adjuvant Agral 90 (mixture of polyethoxylated derivatives of nonylphenol), were assessed on planktonic communities in 18-m3 outdoor mesocosms during a nine-month study. Four mesocosms were treated with fomesafen only (nominal concentration: 40 microg/L), four were treated with the mixture fomesafen-Agral 90 (nominal concentration: 40 microg/L and 90 microg/L, respectively), and four were kept as the controls. Five treatments were performed every three weeks from April 18, 2000. Mean (+/- standard error [SE]) values of fomesafen concentration in water of 62.5 (+/-5.3) and 19.4 (+/-7.6) microg/L were measured at the end of the treatment period in fomesafen- and mixture-treated mesocosms, respectively. Fomesafen, either alone or in mixture with Agral 90, had a significant positive effect on the abundance and biovolume of Cyanobacteria, Cryptophyceae, Dinophyceae, and Bacillariophyceae. Chlorophyceae were inhibited by the herbicide and laboratory toxicity tests confirmed that green algae were more sensitive toward fomesafen than other algal classes. A positive effect of treatments on phytoplankton taxonomic diversity also was observed, indicating that, like natural disturbances of intermediate strength, xenobiotics sometimes may enhance the diversity of algal communities. Fomesafen alone did not have any clear effect on zooplankton. Abundance of calanoid copepods was reduced significantly in the mixture-treated ponds, suggesting either a direct effect of the adjuvant and/or an enhancement of herbicide toxicity by Agral 90. The abundance of other zooplanktonic herbivorous groups increased due to a reduced competition for food for herbivorous species and a higher availability of preys for predators. No algal bloom was observed in the treated ponds, presumably because of grazing pressure and the low availability of nutrients