Differences in Diet of Green (Haliotis fulgens) and Pink (Haliotis corrugata) Wild Abalone along the Pacific Coast of the Baja California Peninsula, Using Stable Isotope Analyses

Stable isotopes (δ¹³C, δ¹⁵N) were used to assess differences in the diets of wild adult Haliotis fulgens and Haliotis corrugata. Temporal variations in the diets of these species were compared using specimens collected monthly during one annual cycle in Laguna La Bocana, whereas comparisons were made with samples taken in October 2012 in Bahía Tortugas. The two species of abalone have different feeding habits year round; H. corrugata showed a constant d15N pattern (between 9.5% and 10.4%), whereas H. fulgens exhibited a seasonal δ15Npattern [the lowest frequency (9.5%) occurred in September and the highest (11.8%) in December], which might indicate that this species fed on the resources that were available at the time. The d13C pattern showed that Laguna La Bocana had depleted values in relation to Bahia Tortugas, indicating different carbon sources. The fact that the d15Npattern of abalone was below the known food sources (macroalgae), suggests the presence of other sources in the diet of adult abalone, such as detritus or epiphytic diatoms.