CHARACTERISATION OF FOOD GUILDS OF THE CLASS GASTROPODA ON THE NORTHEAST ROCKY COAST OF THE GULF OF CALIFORNIA

Abstract

Few detailed studies are available on class Gastropoda ecology in rocky intertidal areas of the Gulf of California, and none have been conducted in significant latitudinal scale for the region in the last 30 years. This study outlines food guilds of the macrogastropod community (≥1 cm) found in the rocky intertidal zone of 13 coastal sites of the northeast Gulf of California (latitudes 27° N - 31° N) through visual census in transects of 40 m perpendicular to the coast with 2 m2 quadrants every 20 m. The results gathered a total of 5823 records of 41 species. The classification for food type included five guilds, of which algivores stood out with the highest (50.87%) abundance; carnivorous predators represented 19.22% of species abundance; carnivores 14.19%, omnivores 14.51% and microalgivores less than 2% of the total. In the intertidal zone algivore abundance significantly decreased at the lowest level while carnivores were well represented in middle and lower levels. Food guild latitudinal distribution was heterogenous without a specific latitudinal pattern, but trophic diversity tended to be higher in sites on latitudes 29° N - 30° N. Non-metric multidimensional scaling demonstrated four principal areas that grouped algivores, predatory carnivores, omnivores, and carnivores (stress = 0.1). This study shows for the first time the diversity of trophic macro-mollusc guilds northeast of the Gulf of California, which highlights the importance and necessity of generating a solid base for detailed class research in the region.