Fatty acid composition and content of seston, zooplankton, benthic invertebrates and fish in Lake Pyhäjärvi and Lake Köyliönjärvi

We evaluated how cyanobacteria bloom, driven by agricultural eutrophication (defined as an increase in nutrients) or global warming, influence fatty acid profiles of phytoplankton, zooplankton (Daphnia + Bosmina), and fish (roach and perch) in eutrophic Lake Köyliöjärvi and mesotrophic Lake Pyhäjärvi. Regarding the nutritional value of food web components, we evaluated changes in the ω-3 and ω-6 polyunsaturated fatty acids (PUFA) of phytoplankton and consumers at different trophic levels. We report the fatty acid results as percentages (%) and content (µg FA mg-1 C-1)., Lipids were extracted from the freeze-dried seston, herbivorous zooplankton (Daphnia + Bosmina), benthic invertebrates, and fish samples in Kimax borosilicate tubes with chloroform-methanol (2:1) mixture. Fatty acids were methylated using mild sulfuric acid. Methyl esterified samples were analyzed on a Shimadzu GC-MS-QP2010 Ultra (Nishinokyo-Kuwabara-Cho, Kioto, Japan) with helium as carrier gas. Column was Zebron ZB-FAME (35 m x 0.25 mm x 0.20 µm). The temperature of the injector was 270 °C and we used a splitless injection mode (for one min). Temperatures of the interface and ion source were 250 °C and 220 °C, respectively. Phenomenex® (Torrance, California, U.S.A.) ZB-FAME column (30 m × 0.25 mm × 0.20 µm) with 5 m Guardian was used with the following temperature program: 50 °C was maintained for one min, then the temperature was increased at 10 °C min-1 to 130 °C, followed by 7 °C min-1 to 180 °C, and 2 °C min-1 to 200 °C. This temperature was held for three minutes, and finally, th..., Diatom 16 PUFA includes 16:2ω7, 16:2ω4, 16:3ω4.
Green algae 16 PUFA includes 16:2ω6, 16:3ω3 and 16:4ω3.
Branched fatty acids (BrFA) includes FA of i14:0, i15:0, a15:0, i17:0 and a17:0.