Changes in the feeding habits of the bat ray Myliobatis californica (Gill 1865) during climatic anomalies off the west coast of the Baja California Peninsula, Mexico

Abstract

The Mexican Pacific was influenced by “La Mancha” and “El Niño”, from 2014 and until 2016. The increase in sea surface temperature influenced the feeding habits of the bat ray (Myliobatis californica) in the northwest of Baja California Sur, Mexico. To evaluate possible changes in the diet, stomach content analysis and analysis of stable isotopes of carbon (δC) and nitrogen (δN) in muscle was performed during normal (2012 and 2013) and anomalous years (2014, 2015, and 2016). During the normal years, the main prey was the crab Dynomene spp. (% Prey Specific Relative Importance Index (PSIRI) = 29.3) and the stomatopod Hemisquilla californiensis (% PSIRI = 10.6). In contrast, during the anomalous years, these preys were replaced by the pelagic red crab Pleuroncodes planipes (% PSIRI = 28.5) and peanut worms Sipunculus spp. (% PSIRI = 7.9). During normal years the median isotopic values recorded were: δC = −16.2‰ and δN = 15.2‰. During the anomalous years, δC was −16.3‰ and δN was 15.1‰. Between the different periods no trophic (p (probability) > 0.05) or isotopic overlaps (p > 0.3) were found. The change in the diet of M. californica during the anomalous years is an adaptive response to the increase in water temperature caused by “La Mancha” and “El Niño”. The massive presence of P. planipes on the northwest coast of Baja California Sur is associated with the increase in water temperature, which makes P. planipes a food source for M. californica.