Planktonic and benthic invertebrates as indicators of water quality in urban ponds (Santa Fe, Argentina)

ARIAS, M.J.; VASCHETTO, P.; REGALDO, L.; MARCHESE, M.; GAGNETEN, A.M.

Cartagena

Congreso; SETAC Latin America 13th Biennial Meeting; 2019

Urban water courses constitute an important source of freshwater for multiple uses. However, they often receive point or diffuse contamination caused by many types of human activities that can potentially turn them into a sink of diverse contaminants. Benthic and zooplanktonic aquatic invertebrates play an important role in the trophic structure, either as a food resource or by acting in the cycling of nutrients. This makes them good indicators of ecosystems health. In this study, composition and structure of benthic and zooplanktonic assemblages of three urban aquatic systems of Santa Fe city (Argentina) were analyzed seasonally. The aim was to assess the main invertebrates bioindicators of water quality and the functional groups for each community. Environmental variables such as temperature, pH, dissolved oxygen, sediment granulometry, organic matter, transparency and depth were analyzed in each aquatic system and season. Even when all the studied systems presented a considerable degree of disturbance, a gradient could be established according to the biotic indexes applied for both communities, from the most disturbed to the less disturbed. These biotic indexes were the Index of Macroinvertebrates of Pampean Rivers (IMRP) for the benthic community and Abundance of rotifers/Abundance of total individuals, Microcrustaceans/Total individuals; Cladocerans/Total individuals and Macrozooplankton/Microzooplankton for the zooplanktonic community. The statistical analyses (Canonical Correspondence Analysis, non-Metric Multidimensional scaling, SIMPER and PERMANOVA) supported the results. Nevertheless, the gradients previously established changed considerably once both communities were analyzed together. This pattern revealed that some indicator taxa are more representative of water quality than others. In this study benthic indicator taxa such as Dero sp., Nais variabilis and Chironomus sp. were important to discriminate the most disturbed system, but for the less disturbed systems, indicator taxa from both communities were necessary to establish the gradient of pollution. Zooplanktonic taxa such as Moinodaphnia macleayi and Daphnia sp. were very representative of slightly disturbed systems, even when there were plenty of benthic taxa. The results highlight the relevance to identify the indicator taxa of each community for a better and comprehensive analysis, to assess the water quality of urban aquatic systems.