Pérez-Posada, I., N., Cabanillas-Terán, R., Rosas-Luis, H.A., Hernández-Arana & A., Sánchez-González (2023). Isotopic niche shift in the sea urchins Echinometra lucunter and E. viridis after massive arrivals of Sargassum in the Mexican Caribbean. Regional Studies in Marine Science. 65: 103064. DOI: 10.1016/j.rsma.2023.103064.
Isabella Pérez-Posada, Nancy Cabanillas-Terán, Rigoberto Rosas-Luis, Héctor A. Hernández-Arana y Alberto Sánchez-González 1
In the Mexican Caribbean, the decomposition of unusual amounts of Sargassum (Sargassum fluitansand S. natans) has caused changes in the benthic community. The aim of this study was to evaluatethe impact of massive pelagic Sargassum arrivals on the trophic structure of sea urchins Echinometra lucunter and E. viridis, using stable isotopes of carbon (d13C) and nitrogen (d15N) to identify variationsin relative proportions of assimilated primary producers in two reef lagoons (Xahuayxol and Xcalak)in the southern Mexican Caribbean. The survey considered two scenarios: (1) with massive Sargassumarrivals (WIMA) in 2018 and (2) without massive Sargassum arrivals (WOMA) in 2017. Results revealeda decreased in d15N and d13C values during WIMA in primary producers and sea urchins. Furthermore,the isotopic mixing models (MixSIAR) indicated that both E. lucunter and E. viridis preferably consumedHalimeda spp. and Thalassia testudinum. The isotopic niche width obtained from Stable Isotope BayesianEllipses in R (SIBER) analysis showed differences between species and localities. In Xahuayxol during WIMA the corrected standard ellipse area (SEAc) of E. lucunter increased while that of E. viridis decreased. However, the latter species had a significant increase in trophic level. In Xcalak duringWIMA, for both sea urchins, the SEAc increased and overlapped while the trophic levels increased significantly. Results suggest that E. viridis in Xahuayxol was better adapted to changes in resource availability, while the niche expansion of E. lucunter in Xahuayxol and E. lucunter and E. viridis inXcalak suggest that sea urchins exhibited a starvation stage due to a decrease in food resources.
Palabras clave: Lagoon reefs; Mesoamerican reef system; Niche breadth; Sea urchins; stable isotopes; Trophic ecology
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