Publications

Graham, N.A.J., Robinson, J.P.W., Smith, S.E., Govinden, R., Gendron, G., Wilson, S.K., 2020. Changing role of coral reef marine reserves in a warming climate. Nat. Commun. 11, 1–8. https://doi.org/10.1038/s41467-020-15863-z

 

Summary: Coral reef ecosystems are among the first to fundamentally change in structure due to climate change, which leads to questioning of whether decades of knowledge regarding reef management is still applicable. Here we assess ecological responses to no-take marine reserves over two decades, spanning a major climate-driven coral bleaching event. Prebleaching reserve responses were consistent with a large literature, with higher coral cover, more species of fish, and greater fish biomass, particularly of upper trophic levels. However, in the 16 years following coral mortality, reserve effects were absent for the reef benthos, and greatly diminished for fish species richness. Positive fish biomass effects persisted, but the groups of fish benefiting from marine reserves profoundly changed, with low trophic level herbivores dominating the responses. These findings highlight that while marine reserves still have important roles on coral reefs in the face of climate change, the species and functional groups they benefit will be substantially altered.

 

Romanov, E.V., Nikolic, N., Dhurmeea, Z., Bodin, N., Puech, A., Norman, S., Hollanda, S., Bourjea, J., West, W., Potier, M., 2020. Trophic ecology of albacore tuna (Thunnus alalunga) in the western tropical Indian Ocean and adjacent waters. Mar. Freshw. Res. https://doi.org/10.1071/MF19332

 

Summary: In this study we investigated the trophic ecology of albacore tuna in the western Indian Ocean and adjacent Atlantic waters based on stomach content analysis using a reconstituted length and weight of prey approach. From 686 non-empty stomachs collected between 2001 and 2015 across three biogeographic provinces, we describe the diet composition of albacore tuna, analyse its feeding habits and investigate the structure and diversity of mid-trophic-level communities. Epipelagic fish were found to be the principal prey by number and reconstituted weight; cephalopods were the second important prey group. Small organisms prevailed in the diet of albacore tuna, with predation on juvenile fish commonplace. Albacore tuna exhibits a flexible, opportunistic feeding strategy, from ram filter feeding on abundant schooling prey to visual predation on large individuals. Prey species richness varied highly across the region. Oligotrophic conditions within the subtropical gyre of the Indian Ocean generated the most diverse mid-trophic-level communities, with less diverse communities occurring in productive areas. Albacore tuna occupies a similar trophic niche throughout the global ocean, foraging on the same prey families and even species. This study indicates overall temporal stability of the Indian Ocean and south-east Atlantic ecosystems where principal prey species remain unchanged over decades.

 

Sardenne, F., Bodin, N., Latour, J.C.-T., McKindsey, C.W., 2020. Influence of lipid separation on the trophic interpretation of fatty acids. Food Webs e00146. https://doi.org/10.1016/j.fooweb.2020.e00146

 

Summary: Fatty acids (FAs) are a common tool to investigate trophic ecology due to the transfer of several FAs across trophic levels. However, some dietary FAs are modified to maintain homeostasis. Therefore, for trophic purposes, there is the question of whether to separate lipid fractions into fatty acids that are physiologically regulated (structural, polar lipids) and those which are not (reserve, neutral lipids). This study compared the effect of lipid separation prior to FA analysis (total lipid versus neutral lipid fraction) on the ecological interpretations for several pelagic and benthic marine consumers. A tissue with high total lipid content, the hepatopancreas (total lipid content >17% dry weight), had similar FA proportions (in relative abundance) in both total and neutral lipid fractions. For lean muscle (total lipid content <10% dry weight), differences in FA proportions between lipid fractions were species-specific. Proportions of some FAs can be converted from one fraction to the other using simple linear models (e.g., 22:6n-3 and 18:1n-9 for pelagic consumers) but most differences in FA proportions cannot be corrected which should be considered when comparing data from the literature. The present study should be extended to other species and tissues to urther elucidate the importance of tissue total lipid content and neutral to total lipid ratio on the difference of dietary interpretations between total and neutral FA proportions. In particular, it would be useful for marine trophodynamic studies to define a guideline of the tissue total lipid content above which lipid separation is not required.