Differential use of food resources by dominant fish of San Ignacio Lagoon, Baja California Sur, Mexico.

Abstract

Se describe el uso de recursos alimentarios en las cinco especies de peces más abundantes en Laguna San Ignacio, Baja California Sur, México (Occidentarius platypogon, Cynoscion parvipinnis, Menticirrhus undulatus, Trachinotus paitensis y Heterodontus francisci). Fueron analizados los espectros tróficos, los cambios temporales, la amplitud de dieta, la diversidad de presas y el traslape trófico. Se identificaron un total de 49 tipos alimenticios, los cuales fueron agrupados en seis grupos taxonómicos: crustáceos, moluscos, anélidos, equinodermos, sipuncúlidos y peces. Los crustáceos y moluscos aportaron un mayor número de presas, representando más del 75% de las presas identificadas. Callinectes bellicosus, Penaeus californiensis, Squilla spp., Donax spp., Lucapinella milleri, Anachis spp. y Bittium spp., fueron las presas más importantes en los espectros descritos. Los espectros alimentarios presentaron diferencias temporales en la composición de presas. Todos los depredadores presentaron valores bajos de amplitud de dieta. Se determinó un bajo traslape trófico, excepto entre O. platypogon y C. parvipinnis, en los que se encontró que la sobreposición de dietas es significativa (> 60%). Los resultados demuestran que cada especie tiene diferentes hábitos alimentarios que les permite segregarse a lo largo de las dimensiones del nicho trófico. Proponemos que la partición de recursos alimentarios es importante solo para peces con mayor traslape trófico. Las diferencias en morfología de sus aparatos alimentarios parecen estar correlacionadas con el tipo de presas consumidas. Differential use of food resources by dominant fish of San Ignacio Lagoon, Baja California Sur, Mexico The use of food resources in five of the most abundant fish species (Occidentarius platypogon, Cynoscion parvipinnis, Menticirrhus undulatus, Trachinotus paitensis and Heterodontus francisci) in San Ignacio Lagoon, Baja California Sur, Mexico is described. Prey composition, seasonal changes, diet breadth, trophic diversity and trophic overlap were analyzed. Forty nine prey items were identified, grouped into six taxonomic groups: crustacea, molluska, osteichthyies, anellida, equinodermata and sipunculida. Crustaceans and mollusks were the most important items recorded, representing over 75% of the identified prey. The crustaceans Callinectes bellicosus, Penaeus californiensis, Squilla spp., megalop larvae of portunids and the mollusks Donax spp., Lucapinella milleri, Anachis spp., and Bittium spp. were the most important prey in the fish species analyzed. Differences in the prey composition and seasonal changes were observed, as well as seasonal changes in the diet breadth. All the predators examined had low percentages of breadth of diet, being characterized as opportunists with low levels of trophic diversity. There was only one case of higher prey overlap between O. platypogon and C. parvipinnis. We concluded that food resource partitioning is very important only in those fish species with higher overlap in their diets. Differences in bucal morphology seem related to prey selection.

Feeding habits ofEucinostomus entomelasandMicropogonias megalopsin Las Guasimas lagoon Gulf of California

“…The food components of M. megalops were similar to those reported for the same scianid by Román-Rodríguez (2000), who found crustaceans, molluscs, ophiuroids, polychaetes, fish and unidentified organic material were the most important in this predator's diet. Feeding preference also agrees with that reported for other genera of the family Scianidae such as: Menticirrhus undulatus (Bocanegra-Castillo et al ., 2000) and Cynoscion parvipinnis (Cruz-Escalona et al ., 2010), but it differs from that found for Cynoscion othonopterus (Román-Rodríguez, 2000) and Micropogonias furnieri (Bertrán et al ., 2013); in both predators, clupeiform fish are the preferred prey ( Cetengraulis mistecetus and Engraulis ringens , respectively) .…”

“…(2007) and Cruz-Escalona et al . (2010), who classify Menticirrhus undulatus, Micropogonias furnieri and Cynoscion parvipinnis as specialist predators because of the high consumption of crustaceans or molluscs.…”