ABSTRACT
Saurida elongata, a warm-water offshore benthic fish, is one of the dominant species in Haizhou Bay and plays an important role in the food web. Based on samples collected from bottom trawl surveys in Haizhou Bay, we examined the feeding habits of Saurida elongata based on both stomach content and stable isotope analyses. The results showed that the main prey species of Saurida elongata were Metapenaeopsis dalei, Loligo spp., Cryptocentrus filifer, Engraulis japonicus, Chaeturichthys hexanema, Apogonichthys lineatus, Syngnathus acus and Callionymus beniteguri. The range of δ13C value was -19.39 to -16.23, with an average value of (-18.01±0.85). There was no correlation between body length and δ13C values. The value of δ15N ranged from 9.56 to 13.36, with an average value of (11.77±0.86), which was significantly positively correlated with body length. There was substantial difference in the contribution of food organism among diffe-rent body length groups. With the increases of body size, predation ability and morphology of feeding organs gradually improved, and the proportion of prey organisms changed, which might be the main reason for the ontogenetic variation in feeding habits. This study could contribute to understand the feeding ecology of snake mullet in Haizhou Bay and provide basic information for the nutritional dynamics of the Haizhou Bay food web.
Subject(s)
Bays , Gastrointestinal Contents , Animals , Carbon Isotopes , China , Feeding Behavior , Food Chain , Habits , Isotopes , Nitrogen IsotopesABSTRACT
Rhinogobius pflaumi is a small-sized, warm-temperate demersal fish species. It is one of the dominant species in fish community, and plays an important role in Jiaozhou Bay ecosystem. The trophic level and feeding habits of R. pflaumi were investigated by carbon and nitrogen stable isotope analysis, based on the data collected from the bottom trawl surveys during May 2011 in Jiaozhou Bay, China in this study. The results showed that the δ15N and δ13C values of R. pflaumi ranged from 11.24 to 13.99 and -20.67 to -18.46, respectively. The mean values of δ15N and δ13C were (12.70±0.70) and (-19.08±0.36), respectively. The mean trophic level of R. pflaumi was (3.62±0.21) for all size classes, ranging from 3.49 to 3.76 for different size classes. There was a significant negative correlation between the δ15N values and standard length, while no significant correlation was observed between δ13C values and standard length. The main prey groups of R. pflaumi were polychaeta, decapoda and mollusca. The trophic contributions of zooplankton and particle organic matter (POM) were relatively low. The similarities of prey species composition among different size classes were more than 92%, indicating that there was no significant difference in feeding habits with different standard lengths. R. pflaumi was an intermediate consumer in Jiaozhou Bay ecosystem. The significant negative correlation between trophic level and standard length might be due to variation in the proportion of different prey groups.
