Feeding ecology of juvenile spiny lobster, Panulirus interruptus, on the Pacific coast of Baja California Sur, Mexico

Abstract

Many aspects of the early life history of the red lobster Panulirus interruptus are little known, including the relationship between habitat structure, food resource availability, and nutrition of juveniles. We investigated the spatial and temporal differences in food intake, diet composition, and nutritional condition of juveniles at two sites along the Pacific coast of the Baja California Peninsula (Mexico) with contrasting oceanographic and biological conditions. One site (Arvin) is located inside a protected bay, Bahía Tortugas, where the waters are cooler and temperate seagrasses and macroalgae are the dominant benthic flora. The second site (Queen) in Bahía Sebastían Vizcaíno was located along a more open coastline where seawater temperatures were higher and the benthic flora more indicative of warmer seas. At both sites, we randomly sampled epifauna within vegetated habitats to estimate the seasonal availability of food resources for juvenile lobsters from autumn 2001 until summer 2002. Concurrently, we used traps to sample P. interruptus juveniles for stomach content analysis. At both sites, Amphipoda, Gastropoda, and Polychaeta dominated the epifauna assemblages, as determined by an Index of Importance. Juvenile P. interruptus primarily consumed crustaceans (mostly amphipods and isopods) and vegetal material (surf‐grass Phyllospadix spp. and calcareous algae), but their food spectrum was wide. Manly's Index of Resource Selection indicated that lobsters preferred some prey (e.g., Brachyurans) over others despite their low Index of Importance. Despite marked differences in the types of food and their availability between sites, there were no significant differences in the nutritional condition (e.g., relative weight of the digestive gland) of lobsters at the two sites. However, the nutritional condition of lobsters was effected during some seasons. In particular, their condition deteriorated during the spring (April 2002) at Arvin, as did the proportion of individuals with empty stomachs. This study shows the feeding adaptation capacity of the juvenile California spiny lobster P. interruptus to different environmental conditions prevalent in Centre Baja California Peninsula.