Seagrass fatty acid profiles as a sensitive indicator of climate settings across seasons and latitudes.

Zostera marina is a dominant meadow-forming seagrass in temperate regions in the northern hemisphere. Here, fatty acid content and composition, and pigmentation, in leaves were evaluated across temporal (April, July, November -2015 and January-2016) and latitudinal (Greenland to southern Spain) environmental gradients. Content of total fatty acids (TFA) in samples collected in Ireland during warmer periods (summer) was 2-3 times lower than in winter and exhibited a lower proportion of polyunsaturated fatty acids (PUFAs), which have high high-nutritional value relative to saturated fatty acids (SAFA). The latitudinal comparison (Greenland to southern Spain) revealed a clear reduction in the proportion n-3 PUFAs and an increase in n-6 PUFA and SAFA, which correlated with the rise in temperature towards southern locations, which correlated with the rise in temperature towards south. Results indicate that future warming may negatively affect its lipid nutritional value. These results demonstrate the capacity of seagrasses to adjust their lipid composition to achieve optimal membrane functionality, suggesting the potential use of FA as an eco-physiological indicator of global change conditions. The results also suggest that future warming may negatively affect the lipid nutritional value of seagrasses.