Effects of a lagoon on performances of a freshwater fishpond in a multi-trophic aquaculture system

Integrated multi-trophic aquaculture (IMTA) is a way to help preserve the environment while maintaining a good level of total production. An ecologically semi-intensive pond system was designed in which a polyculture fishpond was associated with a lagoon planted with macrophytes to bioremediate the water. The properties of this “semi-intensive coupled” system (SIC) were compared to those of semi-intensive (SI) and extensive (E) systems, each of which was contained in a single fishpond with the same fish polyculture (common carp (Cyprinus carpio), roach (Rutilus rutilus), and perch (Perca fluviatilis)) as SIC. E differed in that it had half the initial density of fish, and the fish were not fed. Fish growth performances, water quality (chemical and biological indicators), chlorophyll concentrations, and invertebrate production were measured. The systems were compared based on fish production performances and physicochemical and biological characteristics, and were then described using principal component analysis (PCA). Carp and roach in the two fed systems had higher growth performances than those in E. Compared to SI, the planted lagoon in SIC, induced a decrease of 15% in fish growth performances and of 83% in total chlorophyll concentration (a proxy for phytoplankton) but improved water quality (−34%, −60% and −80%, for the concentrations of total nitrogen, total phosphorus, and blue green algae (for micro-algae in class Cyanophyceae), respectively). According to the PCA, SIC clearly differed from SI in benthic macro-invertebrate production and concentrations of total nitrogen, total phosphorus, and brown algae (for micro-algae in class Dinophyceae or a branch of Bacillariophyta) in the water. SIC differed from E in oxygen parameters (dissolved and saturation), estimated annual zooplankton production, and pH. In conclusion, the properties of a lagoon reveal perspectives for environmentally friendly practices, while using biodiversity and secondary production in order to enhance fish production

Bti sprays do not adversely affect non-target aquatic invertebrates in French Atlantic coastal wetlands

Both the increase in human mobility and climate change contribute to the globalization of vector-borne diseases. Some mosquito species are efficient disease vectors in Europe, thus increasing the risk of epidemic (re)emergence.Bacillus thuringiensis var. israelensis (Bti) is considered as the most efficient larvicide to control mosquito populations with negligible environmental impacts. However, repeated field applications of Bti over many years raise the question of possible long-term effects on non-target invertebrates with putative subsequent alterations of food webs. Environmental effects of Bti have mainly been studied in continental freshwater wetlands. Much less is known for brackish water coastal wetlands. We investigated whether repeated treatments with Bti, applied as VectoBac((R)) WG over seven consecutive years, may affect non-target invertebrate communities in wetlands of the French Atlantic coast. Particular attention was devoted to invertebrates potentially used as food sources by shorebirds and wading birds. Invertebrates were sampled in the water and sediment of control and VectoBac((R))-treated saltmarsh pools between 2006 and 2012. Taxa abundance data were used to calculate community descriptors and to analyse the potential structural changes due to VectoBac((R)) using the principal response curve method and similarity analysis. Physicochemical parameters were measured in the same pools so that homogeneity of the environmental conditions between the control and treated areas could be tested. We demonstrated that long-term use of VectoBac((R)) WG in French Atlantic coastal wetlands had no influence on the temporal evolution of the taxonomic structure and taxa abundance of non-target aquatic invertebrate communities, which is highly driven by abiotic factors. In addition, over the long term, the amount of invertebrates that could be used as food resources by birds is maintained in VectoBac((R))-treated areas.Synthesis and applications. Reduced application rate and targeted spraying of VectoBac((R)) WG in mosquito breeding sites minimize potential environmental impacts of Bacillus thuringiensis var. israelensis (Bti). Even so, surveillance of its possible primary side effects is needed, which requires comparable control and treated areas. Indeed, systematic temporal trends and subtle differences in the range of variation of abiotic factors result in discrepancies between control and treated area in terms of invertebrate abundance, which could be wrongly attributed to VectoBac((R)). Management decisions and mitigation measures may therefore benefit from (i) extending surveillance to a time frame that allows for coverage of the immense temporal variation in taxa abundance and diversity and (ii) the inclusion of environmental variables in the monitoring of non-target animal communities potentially exposed to Bti. Reduced application rate and targeted spraying of VectoBac((R)) WG in mosquito breeding sites minimize potential environmental impacts of Bacillus thuringiensis var. israelensis (Bti). Even so, surveillance of its possible primary side effects is needed, which requires comparable control and treated areas. Indeed, systematic temporal trends and subtle differences in the range of variation of abiotic factors result in discrepancies between control and treated area in terms of invertebrate abundance, which could be wrongly attributed to VectoBac((R)). Management decisions and mitigation measures may therefore benefit from (i) extending surveillance to a time frame that allows for coverage of the immense temporal variation in taxa abundance and diversity and (ii) the inclusion of environmental variables in the monitoring of non-target animal communities potentially exposed to Bti

Effects of a lagoon on performances of a freshwater fishpond in a multi-trophic aquaculture system

Integrated multi-trophic aquaculture (IMTA) is a way to help preserve the environment while maintaining a good level of total production. An ecologically semi-intensive pond system was designed in which a polyculture fishpond was associated with a lagoon planted with macrophytes to bioremediate the water. The properties of this “semi-intensive coupled” system (SIC) were compared to those of semi-intensive (SI) and extensive (E) systems, each of which was contained in a single fishpond with the same fish polyculture (common carp (Cyprinus carpio), roach (Rutilus rutilus), and perch (Perca fluviatilis)) as SIC. E differed in that it had half the initial density of fish, and the fish were not fed. Fish growth performances, water quality (chemical and biological indicators), chlorophyll concentrations, and invertebrate production were measured. The systems were compared based on fish production performances and physicochemical and biological characteristics, and were then described using principal component analysis (PCA). Carp and roach in the two fed systems had higher growth performances than those in E. Compared to SI, the planted lagoon in SIC, induced a decrease of 15% in fish growth performances and of 83% in total chlorophyll concentration (a proxy for phytoplankton) but improved water quality (−34%, −60% and −80%, for the concentrations of total nitrogen, total phosphorus, and blue green algae (for micro-algae in class Cyanophyceae), respectively). According to the PCA, SIC clearly differed from SI in benthic macro-invertebrate production and concentrations of total nitrogen, total phosphorus, and brown algae (for micro-algae in class Dinophyceae or a branch of Bacillariophyta) in the water. SIC differed from E in oxygen parameters (dissolved and saturation), estimated annual zooplankton production, and pH. In conclusion, the properties of a lagoon reveal perspectives for environmentally friendly practices, while using biodiversity and secondary production in order to enhance fish production

Application des isotopes stables à l'étude des conséquences des perturbations environnementales en milieu aquatique

Application des isotopes stables à l'étude des conséquences des perturbations environnementales en milieu aquatique. 3. Séminaire d'Ecotoxicologie de l'INR

Influence of a new fishpond design on invertebrate community biodiversity and secondary production

International audienceThe aim of this study was to compare the impact of three aquaculture production systems on the biodiversity and productivity of aquatic invertebrates. We compared two conventional fishpond designs (extensive and semi-intensive) with a new design combining a semi-intensive carp polyculture fishpond with a planted lagoon, called coupled semi-intensive design. All fishponds were stocked with the same proportions of common carp, roach, and Eurasian perch. Fish density was double in coupled semi-intensive and semi-intensive ponds compared to extensive ponds for which no formulated feed was provided. Benthic macroinvertebrates were sampled in May and September. Zooplankton was sampled monthly from May to November. For benthic macroinvertebrates, community taxonomic richness, biomass, production, and mean individual dry mass were higher in lagoons than in the coupled semi-intensive, semi-intensive and extensive fishponds. Zooplankton production was highest in extensive fishponds and lowest in coupled semi-intensive ponds. Zooplankton production peaked in summer and was lower than benthic macroinvertebrates production in May and September. Asellus aquaticus , whose production was higher in September than May, was the dominant macroinvertebrate in lagoons, but was almost absent from all fishponds. Bosmina longirostris , the most productive plankton taxon, especially in extensive fishponds, reached peak production in July and August. Our study highlighted the functional role of a shallow, fishless, planted lagoon linked to the fishpond for biodiversity and production of benthic macroinvertebrates and zooplankton

Secondary production of freshwater zooplankton communities exposed to a fungicide and to a petroleum distillate in outdoor pond mesocosms

Ecological risk assessment of chemicals in mesocosms requires measurement of a large number of parameters at the community level. Studies on invertebrate communities usually focus on taxonomic approaches, which only provide insights into taxonomic structure changes induced by chemicals. In the present study, abundance, biomass (B), theoretical production (P), and instantaneous P/B ratio were used as endpoints to assess the effects of the commercial form of the dithiocarbamate fungicide thiram (35 mu g/L and 170 mu g/L nominal concentrations) and of the hydrocarbon water accommodated fraction (HWAF) of a petroleum distillate (0.01 mg/L, 0.4 mg/L, 2 mg/L, and 20 mg/L loadings) on the zooplankton community in freshwater pond mesocosms. Endpoints were measured during a 4-wk treatment period (1 pulse/wk) followed by a 5-mo posttreatment period to evaluate zooplankton population recovery. The chlorophyll a concentration in water was significantly increased after treatment with HWAF, whereas it was not affected by thiram treatment. Zooplankton abundance-based analysis showed effects on a limited number of taxa, whereas other endpoints (mainly the P/B ratio) revealed that more taxa were impacted, with recovery depending on the chemical and concentration. Exposure to HWAF mainly had a negative impact on cladocerans, which resulted in top-down effects (between cladocerans and phytoplankton). Thiram negatively affected rotifers and copepods, suggesting more direct toxic effects. The results show that the use of secondary production as an endpoint provides a more comprehensive assessment of potential direct and indirect effects of chemicals on a community, and they also support evidence of alteration in functional processes

Aquatic macroinvertebrate abundance in French experimental polyculture fishponds

Abstract Ponds host a variety of invertebrate species and contribute greatly to global biodiversity. Aquaculture influences macroinvertebrate diversity and productivity in ponds through several practices, such as macrophyte and water management. Fish stocking is also considered controversial for preserving biodiversity through the direct predation upon natural species and changes induced on the biotope. An experiment examined whether compartmentalized ponds with temporarily fish‐free areas had higher fish productivity and macroinvertebrate abundance and diversity than open ponds. The experimental design consisted of two treatments—compartmentalized (C) or open (O)—each applied to three ponds. Roach (Rutilus rutilus), tench (Tinca tinca) and common carp (Cyprinus carpio) were stocked in the ponds in March 2021. Juvenile pikeperch (Sander lucioperca) were stocked in the ponds in June. In the C ponds, three areas were created and opened successively: (C1) corresponding to ¼ of the pond surface to host roach, tench and common carp from March to May; (C2) ¼ of the pond surface restricted to fish from March to May; and (C3) ½ of the surface restricted to fish from March to July, except for juveniles of pikeperch which were stocked in June. We investigated patterns in abundance, dry biomass and productivity of macroinvertebrates four times from March to October. This article presents observed macroinvertebrate abundances and weighted dry biomass, and productivity estimated from them. Overall, 77,749 individuals were identified, of which one‐third were Chironomini and another one‐third were Oligochaeta. The invasive red swamp crayfish (Procambarus clarkii) was found in one pond in October. The two highest taxonomic richness values were found in C ponds (71 and 69 taxa). The lowest taxonomic richness (61 taxa) was in an O pond. Although dry biomass was clearly higher in the C ponds in March, no tendency could be seen between C and O ponds throughout the experiment. No difference in productivity was found between the C and O ponds among the experiment. By reporting macroinvertebrate abundance, biomass, productivity, size classes, developmental stages and high‐resolution taxonomic identification in a freshwater polyculture system, this dataset is one of the first of its kind

Des bioindicateurs pour évaluer l’impact ou la restauration vis-à-vis des pesticides – Invertébrés

Action 9 INRA Thonon-Rennes / ONEMADes bioindicateurs pour évaluer l’impact ou la restauration vis-à-vis des pesticides – Invertébrés. Colloque ONEMA Les méthodes d'évaluation de l'état des eaux : situation et perspectives dans le contexte de la DC

Effects of repeated field applications of two formulations of Bacillus thuringiensis var. israelensis on non-target saltmarsh invertebrates in Atlantic coastal wetlands

Bacillus thuringiensis var. israelensis (Bti) is commonly used for selective control of larval populations of mosquitoes in coastal wetlands. A two year-study was implemented to investigate whether repeated treatments with Bti applied either as a liquid (VectoBac (R) 12AS) or a water-dispersible granule (VectoBac (R) WG) formulation may affect the abundance and diversity of non-target aquatic invertebrates in saltmarsh pools. Taxonomic composition of the invertebrate communities was typical of brackishwater intermittent ecosystems, with a dominance of annelids, crustaceans and nematocerans. Conditions were contrasted between the two years of the survey, both in terms of annual cumulative rainfall and rainfall distribution throughout the year. As a consequence, the hydroperiod and some other environmental characteristics associated with pool drying played a major role in the dynamics of the invertebrate community. In summer 2006, pool drying reduced the abundance of the polychaete worm Nereis diversicolor, of the amphipod crustacean Corophium volutator and of chironomid larvae. These taxa were able to recolonize rapidly the pools after flooding in September 2006. In 2007, rainfall was more regularly distributed across the year, and the pools did not get dry. Hydrozoans, Chironomini and Orthocladiinae larvae, and oligochaetes were more abundant in treated than in control pools, especially in VectoBac (R) WG-treated pools. No adverse effects of the treatments were shown on the abundance of N. diversicolor, C. volutator and midge larvae, suggesting that the availability of these food sources for birds was not negatively affected by Bti applications. It is concluded that, as currently performed in Western France coastal wetlands, land-based treatments of saltmarsh pools for larval mosquito control with Bti, used either as VectoBac (R) 12AS or VectoBac (R) WG, did not adversely impact non-target aquatic invertebrate communities. (C) 2011 Elsevier Inc. All rights reserved

Influence of contaminants on demographic and evolutionary stochastic processes in the freswater snail Lymnaea stagnalis ; an experimental approach

Influence of contaminants on demographic and evolutionary stochastic processes in the freswater snail Lymnaea stagnalis ; an experimental approach. 4. World Congress of SETA