Fatty acid response of the invasive bivalve Limnoperna fortunei fed with Microcystis aeruginosa exposed to high temperature.

The success of Limnoperna fortunei as an invasive freshwater bivalve species is related to its physiological plasticity to endure changes in environmental conditions. The aim of this study was to investigate the physiological responses of L. fortunei after feeding on Microcystis aeruginosa grown at 26 °C (control) and 29 °C during 10 days. At the beginning, we measured biomass, fatty acids (FAs) composition on Cyanobacteria grown at both temperatures at different time intervals. Afterwards, mussels were fed with the thawed M. aeruginosa cells and their FA profile was measured after 15 days of feeding. M. aeruginosa exposed to 29 °C had the highest content of the FAs 18:2ω6 and cis-18:1ω9. The FA profile of the consumer L. fortunei fed with M. aeruginosa cultures grown at 29 °C was also significantly different to those fed with cultures grown at 26 °C, with a significant increased Eicosapentaenoic acid (EPA, 20:5ω3) and Arachidonic acid (ARA, 20:4ω6) concentrations. L. fortunei was already known to be physiologically adapted to live at 29 °C, but our results also shown a high biosynthesis of EPA and ARA (increase of 70 and 40% respectively, compared with 26 °C) and avoided the lipid peroxidation of both FAs. This increased EPA and ARA biosynthesis may be an important source of ω3 and ω6 polyunsaturated FAs (PUFAs) for higher trophic levels, such as the pelagic fishes or birds that mainly prey on these mussels. The transfer of the cyanobacterial response at higher temperature to higher trophic levels will influence the overall functioning of freshwater bodies.