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Titre : Eutrophication: are mayflies (Ephemeroptera) good bioindicators for ponds? Type de document : texte imprimé Auteurs : N. MENETREY ; B. OERTLI ; M. Sartori ; A. Wagner ; J. B. Lachavanne Année de publication : 2008 Article en page(s) : pp 125-135 Catégories : Ecoplanète
Ephémère ; Ephemeroptera ; Eutrophication ; EUTROPHISATION ; macroinvertebratesRésumé : Ephemeroptera larvae are recognized worldwide for their sensitivity to oxygen depletion in running waters, and are therefore commonly used as bioindicators in many monitoring programmes. Mayflies inhabiting lentic waters, like lakes and ponds, in contrary have been poorly prospected in biomonitoring. For this purpose, a better understanding of their distribution in lentic habitats and of the relations of species presence with environmental conditions are needed. Within this framework, 104 ponds were sampled in Switzerland. The Ephemeroptera are found to be an insect order particularly well represented in the ponds studied here (93% of the lowland ponds). Nevertheless, in terms of diversity, they are relatively poorly represented (mean species number = 1.9). Two species dominated: Cloeon dipterum (Baetidae) and Caenis horaria (Caenidae). The investigations contributed to the updating of the geographical distribution of the species in Switzerland, as many of the observations appear to be from new localities. The trophic state of ponds appears here to be important for Ephemeroptera communities. First, there is a negative relationship between total phosphorus (TP) concentrations and species richness. Second, the presence of Caenis horaria or Cloeon dipterum is dependent on the trophic state. Caenis horaria is most closely associated with low levels of TP concentrations, while Cloeon dipterum appears to be less sensitive, and is most frequently found in hypertrophic conditions. A probable consequence of these relations, is that Baetidae are always present when Caenidae are also present. Contrastingly, Baetidae is observed as the only mayflies family present in several ponds.
in Hydrobiologia > n°597 (2008) . - pp 125-135[article]
Titre : Aquatic eutrophication promotes pathogenic infection in amphibians Type de document : texte imprimé Auteurs : T. Pieter J. Johnson ; M. Jonathan Chase ; L. Katherine Dosch ; B. Richard Hartson ; A. Jackson Gross ; J. Don Larson_x0001_ Année de publication : 2007 Article en page(s) : pp 15781-15786 Catégories : Ecoplanète
amphibian ; AMPHIBIEN ; disease ; EUTROPHISATION ; MALADIERésumé : The widespread emergence of human and wildlife diseases has challenged ecologists to understand how large-scale agents of environmental change affect host-pathogen interactions. Accelerated eutrophication of aquatic ecosystems owing to nitrogen and phosphorus enrichment is a pervasive form of environmental change that has been implicated in the emergence of diseases through direct and indirect pathways. We provide experimental evidence linking eutrophication and disease in a multihost parasite system. The trematode parasite Ribeiroia ondatrae sequentially infects birds, snails, and amphibian larvae, frequently causing severe limb deformities and mortality. Eutrophication has been implicated in the emergence of this parasite, but definitive evidence, as well as a mechanistic understanding, have been lacking until now. We show that the effects of eutrophication cascade through the parasite life cycle to promote algal production, the density of snail hosts, and, ultimately, the intensity of infection in amphibians. Infection also negatively affected the survival of developing amphibians. Mechanistically, eutrophication promoted amphibian disease through two distinctive pathways: by increasing the density of infected snail hosts and by enhancing per-snail production of infectious parasites. Given forecasted increases in global eutrophication, amphibian extinctions, and similarities between Ribeiroia and important human and wildlife pathogens, our results have broad epidemiological and ecological significance.
in PNAS > n°104 (2007) . - pp 15781-15786[article]Effects of agricultural pond eutrophication on survival and health status of Scinax nasicus tadpoles / Paola Peltzera, M. (2007)
Titre : Effects of agricultural pond eutrophication on survival and health status of Scinax nasicus tadpoles Type de document : texte imprimé Auteurs : M. Paola Peltzera ; C. Rafael Lajmanovicha ; C. Juan Sanchez-Hernandez ; C. Mariana Cabagna ; M. Andres Attademo ; Agustin BASSO Année de publication : 2007 Catégories : Ecoplanète
amphibian ; AMPHIBIEN ; EUTROPHISATIONRésumé : To test the hypothesis that eutrophication ponds modulate some aspects of the health responses and survival of anuran tadpoles, we conducted field experiments using Scinax nasicus as sentinel organism to evaluate the quality of two ponds filled with agricultural runoff in a dominant agricultural landscape of Mid-Western Entre Rı?os Province (Argentina). The survival, growth and development rates, erythrocytes nuclei aberrations, parasite infection, and brain cholinesterase activity were monitored after seven days of exposure. Water samples from the ponds were also analyzed for physico-chemical variables and levels of pesticide residues. Residues of organochlorine pesticides and nutrients were higher in the agricultural ponds with respect to those from the control pond. We suggest that the interactions among washed-off nutrients and pesticides from agriculture and environmental factors account for deleterious effects on S. nasicus survival, growth and development rate, thereby compromising their health status. These effects can lead, in turn, to an increase in tadpole vulnerability to opportunistic parasites, erythrocytes nuclei aberrations or hemolysis. r 2007 Elsevier Inc. All rights reserved.
