Phenotypic and genotypic adaptations in a riverine green alga (Chlorophyceae, Selenastraceae) as a response to long-term exposure to chemical stress

• Herbicide pollution is a common problem in agricultural streams due to their extensive use and their unwanted effects on non-target species inhabiting these systems. Selanastraceae is a family of green algae that are particularly dominant in freshwater, making them a key component in the base of the food chain and an important part of the oxygen production. Therefore, it is crucial from a conservation point of view to accurately monitor the ecotoxicological impact of herbicides on this group of algae, not only on a short-term scale (e.g. days or weeks), but also in a long-term perspective (e.g. months and years). In this work, phenotypic and genotypic differences are studied between different strains of a population of Kirchneriella (Chlorophyceae, Selenastraceae) isolated from a stream polluted by herbicides over a 20-year period (Skivarpsån, SE Sweden). According to mixture toxicity modelling performed on data obtained from the Swedish pesticide monitoring program, the main drivers of algal toxicity in this river are the herbicides diflufenican (carotenoid synthesis inhibitor) and isoproturon (PSII inhibitor). Three strains of the isolated algae are examined in this study: two strains from the field that have been exposed to different levels of herbicides and one laboratory strain that has never been exposed to herbicide pollution. The taxonomy of this algae is investigated by light microscopy and DNA barcoding analyses (chloroplast 23S rRNA gene). Phenotypic differences between the strains are examined as impacts on growth rate, cell size, photosynthetic activity (chl fluorescence measurements), pigment content and sensitivity to the specific herbicides mentioned earlier (EC50s). Genotypic differences are studied as single nucleotide polymorphisms thought to be induced through exposure to diflufenican and isoproturon on pds and psbA genes via PCR amplification, cloning and sequencing. The results obtained from this project will contribute to a better understanding of genetic and phenotypic adaptations in green algae as a response to herbicide pollution (evolutionary toxicology) and their implications for ecological functions.

Subject headings

NATURVETENSKAP  -- Biologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences (hsv//eng)

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

Keyword

Green algae

herbicides

adaptation

Publication and Content Type

vet (subject category)

kon (subject category)