THE CORRELATION BETWEEN BENTHIC INVERTEBRATE PRODUCTIVITY AND FISH DENSITY AT STREAMS

Abstract

Within riverine ecosystems, fish and benthic invertebrates have crucial ecological roles, contributing to the overall functioning and biodiversity of these aquatic environments. The purpose of this study is to describe the relationship between the productivity of benthic invertebrate communities and the density of fish populations in upstream and downstream sections across four European countries. Sampling involved the collection of benthic invertebrates and fish. Data analysis included estimation of invertebrate diversity, density, biomass, and growth rates, as well as assessment of fish condition and density. The correlation between invertebrates and fish were examined and linkages between these factors in both organisms were explored. Also, these connections were compared in four countries under investigation. My results suggest that different countries exhibited various relations among the examined factors concerning these two organisms. Most countries showed higher invertebrate density upstream, a trend that aligns with the density and condition of fish in Sweden and France with no reliable relation in other countries. The highest biodiversity in benthic invertebrate groups is observed in France, which positively correlates with fish density and condition in this country. The taxons with the highest biomass included Hemiptera and Odonata, however, the Hydracarina's small size made it difficult to measure them. The highest growth rate of insects was observed in Portugal, showing no correlation with the abundance and condition of fish. Among benthic invertebrates, Diptera showed the highest productivity based on growth rate across all sites, with Trichoptera displayed the lowest. In this study, it is shown that although significant relationships are not found between benthic invertebrates and fish in all countries, invertebrates can be utilized in the evaluation of various domains such as ecological health assessments, water quality monitoring, and ecosystem functioning, all of which can affect the fish.