Metacyclops Minutus And Daphnia Magna Interspecific Competition Coefficients Under Co2-Mediated Acidification

Acidification diminishes diversity, biomass, and changes aquatic communities by direct and indirect impacts. Changes in the interspecific competition under acidification would alter the aquatic-system community structure in the projected future scenarios. The aim of the present study was to assess the effects of CO2-mediated acidification on two zooplankton species and its impact on the ecological relationship between them. Copepod, Metacyclops minutus, and cladoceran, Daphnia magna, which compete for food and coexist in freshwater ecosystems, were exposed to CO2 injection conditions in monoculture (single species) and polyculture (both species) for 33 days. Three replicates of each treatment (control, pH 6.5, mono and polyculture) were maintained under laboratory-controlled conditions. Population growth rate and carrying capacity were selected as population endpoints. Differences in M. minutus population response under high CO2 concentration led to a positive effect on the abundance of copepod population in polyculture condition, while D. magna showed lower abundance. Despite the higher abundance of copepods under acidification in polyculture condition, in terms of biomass, cladocerans were still dominant by the end of the experimental period. The results highlight the need to consider interspecific interactions when evaluating the harmful effects of acidification, especially in conservation decision-making.