A triad of kicknet sampling, eDNA metabarcoding, and predictive modeling to assess aquatic macroinvertebrate biodiversity

Monitoring freshwater biodiversity is essential to understand the impacts of human activities and for effective management of ecosystems. Thereby, biodiversity can be assessed through direct collection of targeted organisms, through indirect evidence of their presence (e.g. signs, environmental DNA, camera trap, etc.), or through extrapolations from species distribution models (SDM). Differences in approaches used in biodiversity assessment, however, may come with individual challenges and hinder cross-study comparability. In the context of rapidly developing techniques, we compared a triad of approaches in order to understand assessment of aquatic macroinvertebrate biodiversity. Specifically, we compared the community composition and species richness of three orders of aquatic macroinvertebrates (mayflies, stoneflies, and caddisflies, hereafter EPT) obtained via eDNA metabarcoding and via traditional in situ kicknet sampling to catchment-level based predictions of a species distribution model. We used kicknet data from 24 sites in Switzerland and compared taxonomic lists to those obtained using eDNA amplified with two different primer sets. Richness detected by these methods was compared to the independent predictions made by a statistical species distribution model using landscape-level features to estimate EPT diversity. Despite the ability of eDNA to consistently detect some EPT species found by traditional sampling, we found important discrepancies in community composition between the two approaches, particularly at local scale. Overall, the more specific set of primers, namely fwhF2/EPTDr2n, was most efficient for the detection of target species and for characterizing the diversity of EPT. Moreover, we found that the species richness measured by eDNA was poorly correlated to the richness measured by kicknet sampling and that the richness estimated by eDNA and kicknet were poorly correlated with the prediction of the statistical model. Overall, however, neither eDNA nor the traditional approach had strong links to the predictive models, indicating inherent limitations in upscaling species richness estimates. Future challenges include improving the accuracy and sensitivity of each approach individually yet also acknowledge their respective limitations, in order to best meet stakeholder demands addressing the biodiversity crisis we are facing.

Homogenization of Macroinvertebrate Assemblages and Asiatic Clam Corbicula fluminea Invasion in a River of the Arid Patagonian Plateau, Argentina

The invasion of the Asiatic clam Corbicula fluminea in South America has already reached Patagonia. Despite the well-known direct and indirect impacts that this species exerts on fresh-water ecosystems, particularly on benthic communities, few studies have been undertaken on its effect on the composition and structure of aquatic macroinvertebrate assemblages. This study evaluated the effects of the invasion of the Asiatic clam C. fluminea on the aquatic macroinvertebrate assemblages of the Limay River, one of the most important rivers of the arid plateau of Argentinian Patagonia. As this river is currently in the process of being invaded, it was possible to compare invaded and non-invaded sites. Invaded sites displayed a certain homogenization of their constituent species and functional composition. Non-metric multidimensional scaling, similarity analysis and similarity percentages showed negative or positive influence of the presence of this species on the abundance of some taxa, due to competition for resources in this low-productivity Patagonian ecosystem. The deposition of the faeces and pseudo-faeces of C. fluminea enriches the organic content of the sediments. However, its pedal feeding can function as a competitive strategy: by consuming its own deposited organic matter when food is scarce, the amount available to other macroinvertebrates is reduced. This paper is the first contribution on the impact of this invasion on northern Patagonia’s aquatic macroinvertebrate assemblages.

AQUATIC MACROINVERTEBRATE STRUCTURE AND DIVERSITY IN ANGUEDEDOU STREAM (ANGUEDEDOUBASIN : COTE DIVOIRE)

Aquatic macroinvertebrates play an important rôle in ecosystems and are usually used as bioindicators to assess their health. This study aim to assess the structure and diversity of these organismson one hand and the effect of the environmental variables on the characteristics of their communities in Anguededou Stream basin (Côte dIvoire) on the other hand. Six stations were monthly sampled during one year period (March 2018 - February 2019). A total of 171 taxa belonging to 77 famillies and 14 orders were recorded. The Insecta class was the most diversified with 150 taxa (87.20% of total species richness) followed by the Gasteropoda, Malacostraca, Acheta and one species in Oligocheta. The highest values of diversity indices were collectedin the upstream station A1 while highest values of Sorensen similarity index were found between the midstream stations (i.e. A3, A4, A5). A strong positive correlation between conductivity, turbidity, salinity, and a negative correlation with dissolved oxygenwas found with the Chironominae subfamily, and the species Diplonychus sp., Hydrobius sp., Hydracharina sp., Hydrochara sp. and Physa marmorata, while the Tanypodiinae subfamily was highly associated with increased of dissolved oxygen. Macroinvertebrates diversity and species composition was found significantly affected by anthropogenic disturbances.

Assessing the Usefulness of the Automated Monitoring Systems ECOTOX and DaphniaTox in an Integrated Early-Warning System for Drinking Water

This study assesses the suitability of the behavioural image analysis systems ECOTOX and Daphnia Tox for inclusion in an integrated early-warning system for drinking water quality to be implemented in Canada. Results of behavioural parameters measured by ECOTOX using Euglena gracilis are compared to visual observations of E. gracilis behaviour after exposure to atrazine, tributyltin, and copper to determine the automated system's sensitivity. The usability of the Daphnia Tox automated system is assessed using the aquatic macroinvertebrate species Daphnia magna and Hyalella azteca. The possible use of the rotifers Brachionus calyciflorus and Brachionus havanensis with the ECOTOX system is also assessed. Findings indicate that at the present state ECOTOX and DaphniaTox are not suitable for inclusion in an early-warning system, but based on visual observation the parameters measured are sensitive to the contaminants tested and consistent, and with suggested modifications these systems have the potential to be fitting additions in an early-warning system.

Assessing the Usefulness of the Automated Monitoring Systems ECOTOX and DaphniaTox in an Integrated Early-Warning System for Drinking Water

This study assesses the suitability of the behavioural image analysis systems ECOTOX and Daphnia Tox for inclusion in an integrated early-warning system for drinking water quality to be implemented in Canada. Results of behavioural parameters measured by ECOTOX using Euglena gracilis are compared to visual observations of E. gracilis behaviour after exposure to atrazine, tributyltin, and copper to determine the automated system's sensitivity. The usability of the Daphnia Tox automated system is assessed using the aquatic macroinvertebrate species Daphnia magna and Hyalella azteca. The possible use of the rotifers Brachionus calyciflorus and Brachionus havanensis with the ECOTOX system is also assessed. Findings indicate that at the present state ECOTOX and DaphniaTox are not suitable for inclusion in an early-warning system, but based on visual observation the parameters measured are sensitive to the contaminants tested and consistent, and with suggested modifications these systems have the potential to be fitting additions in an early-warning system.