Diatom responses to sewage inputs and hydrological alteration in Mediterranean streams

• Published in: Environmental pollution (1987) 2018-07, Vol.238, p.369-378
• Main Authors: Tornés, Elisabet, Mor, Jordi-René, Mandaric, Ladislav, Sabater, Sergi
• Format: Article
• Language: English
• Subjects: Chemical pollution; Diatoms; Hydrological alteration; Mediterranean rivers; Nutrients; Pharmaceutically active compounds (PhACs); Teratologic diatoms
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2018.03.037

We analyzed the conjoint effects of sewage inputs and hydrological alteration on the occurrence of teratological forms and on the assemblage composition of stream benthic diatoms. The study was performed in 11 Mediterranean streams which received treated or untreated urban sewage (Impact sites, I), whose composition and morphological anomalies were compared to upstream unaffected (Control, C) sites. The impact sites had high concentrations of ammonium, phosphorus, and pharmaceutical compounds (antibiotics, analgesics, and anti-inflammatories), particularly in those receiving untreated sewage. Impact sites had a higher proportion of teratological forms as well as a prevalence of diatom taxa tolerant to pollution. The differences in the diatom assemblage composition between the paired C and I sites were the largest in the impacted sites that received untreated sewage inputs as well as in the systems with lower dilution capacity. In these sites, the diatom assemblage was composed by a few pollution-tolerant species. Mediterranean river systems facing hydrological stress are highly sensitive to chemical contamination, leading to the homogenization of their diatom assemblages. [Display omitted] •A set of 11 paired sites were studied for their diatom response to hydrological and chemical stress.•The sites receiving untreated sewage had high concentrations of nutrients, organic matter and pharmaceutical compounds.•A higher proportion of deformities occurred with higher chemical impact.•Mediterranean rivers facing hydrological stress are highly sensitive to chemical contamination, causing homogenization to their diatom assemblages. Hydrologically stressed streams are highly sensitive to chemical contamination, causing the homogenization of diatom assemblages.