Porifera of the Pasvik River (Northern Fennoscandia): microbiological and chemical observations in Spongilla lacustris (Linnaeus, 1759) and Ephydatia muelleri (Lieberkühn, 1856)

Description

Porifera are generally considered optimal sentinels to detect the presence of contaminants in the environment, and the associated bacterial communities can be shaped by their occurrence. In this context, freshwater sponges are of increasing interest due to their capability to filter large volumes of water and sensitivity as bioindicators to assess the environmental health of aquatic habitats. This feature holds even greater importance in remote environments, such as Arctic areas and their freshwater habitats. Within the INTERACT project BIP (Grant Agreement N. 730938), specimens of the sponge species Spongilla lacustris (Linnaeus, 1759) and Ephydatia muelleri (Lieberkühn, 1856) were collected from the Pasvik River (Norway), together with sediment and water samples. Physical-chemical parameters were measured at sampling time. Samples were analysed for bacterial diversity by NGS, total prokaryotic counts by DAPI-staining, microbial enzymatic activities (leucine aminopeptidase, LAP, beta-glucosidase, GLU, alkaline phosphatase, AP), and concentration of emerging and legacy contaminants (e.g. pharmaceutical products-PPs, pesticides, polychlorobiphenyls, polycyclic aromatic hydrocarbons-PAHs). Among PPs investigated, only ciprofloxacin and diclofenac were detected in the sponge tissues, and their concentrations were lower than those measured in sediment. Sulfamethoxazole, trimethoprim, tetracycline and ibuprofen occurred only in water and sediment. Some PAHs and Dieldrin were more concentrated in the sponge than in abiotic samples, whereas comparable amounts of PCBs were determined in the sponge and sediment. Proteobacteria (Alpha- and Gammaproteobacteria) predominated in the sponge-associated bacterial communities, which differed from those observed for sediment and water. Results on site- and/or sponge species specificity of microbiological and chemical data are discussed.

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