Abstract
In the marine environment, macroalgae face changing environmental conditions and some species are known for their high capacity to adapt to the new factors of their ecological niche. Some macroalgal metabolites play diverse ecological functions and belong to the adaptive traits of such species. Because algal metabolites are involved in many processes that shape marine biodiversity, understanding their sources of variation and regulation is therefore of utmost relevance. This work aims at exploring the possible sources of metabolic variations with time and space of four common algal species from the genus Lobophora (Dictyotales, Phaeophyceae) in the New Caledonian lagoon using a UHPLC-HRMS metabolomic fingerprinting approach. While inter-specific differences dominated, a high variability of the metabolome was noticed for each species when changing their natural habitats and types of substrates. Fatty acids derivatives and polyolefins were identified as chemomarkers of these changing conditions. The four seaweeds metabolome also displayed monthly variations over the 13-months survey and a significant correlation was made with sea surface temperature and salinity. This study highlights a relative plasticity for the metabolome of Lobophora species.
Highlights
Together with marine sponges, macroalgae represent a high source of chemical diversity, called specialized metabolites
A total of 326 features were detected in L. rosacea (LR), 310 in L. sonderii (LS), 404 in L. monticola (LM), and 436 in L. obscura (LO)
Supervised analyses Powered Partial Least-Squares-Discriminant Analysis (PPLS-DA) (Fig. 1) conducted for each species supported a significant effect of time on the metabolomic fingerprinting (CERLR = 0.279, CERLS = 0.303, CERLM = 0.214, CERLO = 0.507, p = 0.001; CER = Mean classification error rate with p-value after double cross model validation)
Summary
Macroalgae represent a high source of chemical diversity, called specialized metabolites. Even if the best known and studied ecological role of these metabolites is the deterrence against competitors and herbivores[5,6], they can act as defense against pathogens[7,8] (e.g. bacteria, fungus, virus), epibionts[9], UV protector[10] or sexual pheromones[11] These chemicals might be involved in the competition for space with other benthic organisms[12,13]. Changes in Asparagopsis taxiformis metabolomic fingerprint were observed after contact with the coral Astroides calycularis[22] and different coral-algal assemblages can alter the coral metabolome[23] These above-mentioned studies indicate that the metabolome of macroalgae is influenced by abiotic and biotic factors, supporting its involvement in biological processes and adaptation to the environment. We studied the spatial metabolomic variation of three species, either in their natural habitat by looking at different sites across the lagoon (five sites), or after short-term in situ cross-transplantations between different habitats (two species, three habitats)
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