Boyen, J., M.T. Rodríguez, B. Vlaeminck, P. Fink, P.I. Hablützel & M. De Troch. (2023). Multiple climate drivers interactively affect biosynthesis of polyunsaturated fatty acids in the benthic harpacticoid copepod Platychelipus littoralis. Chapter 4. Ph.D. Dissertation, University of Ghent. :109-134.
514203
Boyen, J., M.T. Rodríguez, B. Vlaeminck, P. Fink, P.I. Hablützel & M. De Troch
2023
Multiple climate drivers interactively affect biosynthesis of polyunsaturated fatty acids in the benthic harpacticoid copepod Platychelipus littoralis. Chapter 4.
Ph.D. Dissertation, University of Ghent
:109-134.
Publication
Available for editors
Excess greenhouse gas emissions and the resulting global warming and ocean acidification heavily impacts marine organisms and their functioning. One major consequence is the reduction in long-chain polyunsaturated fatty acid (LC-PUFA) production by marine microalgae due to ocean warming. Copepods, as primary consumers of microalgae, have been found to possess a unique capacity for endogenous LC-PUFA biosynthesis, and thus might be able to cope with a reduced dietary LC-PUFA availability. However, this LC-PUFA biosynthesis mechanism may also be itself negatively impacted by changes in oceanographic conditions. In this study, we performed a laboratory experiment to assess the interactive effects of two projected direct (ocean warming of +3 °C and ocean acidification of -0.4 pH) and one indirect (dietary LC-PUFA deficiency) climate drivers on the fatty acid composition and LC-PUFA biosynthesis (measured by quantitative RT-PCR) of the benthic harpacticoid copepod Platychelipus littoralis (Brady, 1880), and hypothesized increased LC-PUFA biosynthesis for all three drivers. We found that when exposed to multiple stressors, the lipid profile of copepods contained fatty acids with shorter chains and fewer unsaturations. Specifically, copepods were able to maintain the relative concentration of the physiologically important LC-PUFA docosahexaenoic acid (DHA) at base-line levels on a LC-PUFA deficient diet at contemporary temperatures, but DHA concentrations dropped significantly when exposed to higher temperatures. Similarly, expression of the DHA biosynthesis genes fed and elovl1a increased to compensate with dietary LC-PUFA deficiency, but did not exceed base-line levels when the copepods were simultaneously exposed to ocean acidification. The expression of the front-end desaturase and multiple elongases was correlated positively with concentrations of C 18 precursors and negatively with those of LC-PUFAs such as DHA, further proving their role as LC-PUFA biosynthesis enzymes. Overall, our findings suggest that ocean warming and acidification may limit the capacity of benthic copepods to biosynthesize their own LC-PUFAs when dietary inputs are disrupted, impairing their contribution towards global LC-PUFA availability for higher trophic levels.
