Mediterranean seagrass ecosystems are endangered by increased colonization of Caulerpa species, which may replace them, affecting key ecosystem processes. The fish Sarpa salpa is one of the main macroherbivores in the western Mediterranean seagrass meadows which is known to feed on a wide range of macroalgae such as Caulerpa species.
This study investigates the importance of S. salpa hebivory pressure on C. prolifera and C. cylindracea compared to Posidonia oceanica and Cymodocea nodosa in a mixed meadow, using a combination of field experiments and dietary analyses.
The obtained results show that S. salpa may have a variable diet, although with a consistent selection of mixed patches with C. nodosa and C. prolifera. The authors highlight that when seagrass leaves are not epiphytized, fish prefer feeding on C. prolifera, which shows the dietary role of epiphytes. The authors suggest that although C. cylindracea consumption was not observed, the fact that it was found within stomach contents shows that S. salpa may eventually adapt to feeding on this new resource.
It is concluded that although the study shows the importance of C. nodosa and C. prolifera in the diet of S. salpa, herbivory in Mediterranean meadows can be highly variable and mediated by multiple factors. Therefore, the authors highlight the need to carry out a multiple methodological approach for a better understanding of herbivory patterns on heterogeneous habitats subjected to seasonal variation.
Marco-Méndez C, Ferrero-Vicente LM, Prado P, Sánchez-Lizaso JL (2017) Epiphytes and nutrient contents influence Sarpa salpa herbivory on Caulerpa spp vs. seagrass species in Mediterranean meadows. Estuarine, Coastal and Shelf Science 184:54-66