Rapid responses of pristine marine planktonic communities in experimental approach to diuron and naphthalene (Juan de Nova Island, Western Indian Ocean)

Planktonic communities from Juan de Nova lagoon were submitted to a single exposure of diuron or naphthalene in triplicate outdoor 40-L mesocosms for 5 days. The study followed the temporal changes assemblages by determining abundances and taxonomic level microbial (heterotrophic prokaryotes, picocyanobacteria, heterotrophic protists phytoplankton) metazooplankton communities. Exposure both contaminants did not result significant phytoplankton abundances. Microscopic identification demonstrated dominance Bacillariophyta (mostly Chaetoceros tenuissimus) accounting more than 95% microalgae detected all mesocosms. Using 18S rRNA metabarcoding, proportion eukaryotic operational units (OTUs) highlighted most groups. Diuron had no effect on abundance picoheterotrophs, ciliates, whereas positive prokaryotes. Metazooplankton was significantly modified under contaminant exposure, except copepods nauplii presence diuron. Multivariate analysis indicated responses linked experimental time conditions. also revealed modification trophic relationships among over time, dominant multivorous food web after 48h towards reduced loop 120h experiment time.