Is there a feeding selectivity of Sarpa salpa over Caulerpa spp vs. seagrasses in Mediterranean meadows?
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1
University of Alicante, Marine Science and Applied Biology, Spain
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2
IRTA, Aquatic ecosystems, Spain
Mediterranean seagrass ecosystems are endangered by increased colonization of Caulerpa species, which may replace them, affecting key ecosystem processes such as herbivore preferences and the local herbivory pressure. The fish Sarpa salpa (L.) is one of the main macroherbivores in the western Mediterranean seagrass meadows which is also known to feed on a wide range of macroalgae such as Caulerpa species providing a certain resistance to invasion of native assemblages. In this study we investigate if S. salpa feed selectively on Caulerpa spp vs. seagrasses and we quantify consumption rates in order to elucidate the potential role of this herbivore on the spread of invasive species in Mediterranean seagrass meadows. For this aim, during summer-autumn 2012 we compared S. salpa herbivory on C. prolifera and C. cylindracea to that on Posidonia oceanica and Cymodocea nodosa in a mixed meadow. A combination of field experiments and dietary analyses were used to investigate consumption rates, dietary contributions, and feeding preferences for the different macrophytes, including the role of epiphytes and nutrient contents in mediating fish herbivory. In summer, C. nodosa was the most consumed macrophyte, probably influenced by higher fish densities, higher nutritional quality of leaves and epiphytes, and by differences in epiphyte community structure. Feeding observations suggest that fish may have a variable diet, although with a consistent selection of mixed patches with C. nodosa and C. prolifera. Indeed, food choice experiments suggest that when seagrass leaves are not epiphytized, fish prefer feeding on C. prolifera. Gut content and stable isotopic analyses supported the dietary importance of epiphytes and C. prolifera but also suggested that C. cylindracea could occasionally be an important food item for S. salpa. Our results highlight the role of epiphytes in S. salpa feeding decisions but also suggest that C. nodosa and C. prolifera may have an important contribution to fish diet. This variability in S. salpa feeding decisions confirms the need to carry out multiple dietary approaches for understanding of the potential effects of herbivory in complex systems with multiple macrophytes species.
Acknowledgements
This research was funded by the Department of Marine Science and Applied Biology (University of Alicante). We thank Pablo Sánchez-Jérez and especially David Izquierdo-Gomez and Pablo Arechavala-López whose support has been essential in providing S. salpa individuals and teaching us dissection and field measurement techniques.
Keywords:
food choice,
Cymodocea nodosa,
Posidonia oceanica,
Caulerpa prolifera,
Caulerpa cylindracea.
Conference:
XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016.
Presentation Type:
Oral Presentation
Topic:
1. ECOLOGY, BIODIVERSITY AND VULNERABLE ECOSYSTEMS
Citation:
Marco-Méndez
C,
Ferrero-Vicente
L,
Prado
P and
Sáchez-Lizaso
J
(2016). Is there a feeding selectivity of Sarpa salpa over Caulerpa spp vs. seagrasses in Mediterranean meadows?.
Front. Mar. Sci.
Conference Abstract:
XIX Iberian Symposium on Marine Biology Studies.
doi: 10.3389/conf.FMARS.2016.05.00056
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Received:
27 Apr 2016;
Published Online:
02 Sep 2016.
*
Correspondence:
PhD. Candela Marco-Méndez, University of Alicante, Marine Science and Applied Biology, Alicante, 03690, Spain, candela.marco@ua.es