História natural de Labrisomus (Actinopterygill: Labrisomidae) da costa nordeste do Brasil: distribuição espacial, densidade e ecologia comportamental

Abstract

The Labrisomus (Labrisomidae) are small carnivores, sedentary and strongly associated with the reef bottom, are sexually dimorphic and exhibit territorial behavior. Here, we studied the influence of habitat complexity on density and spatial distributions, including the ontogenetic stages of Labrisomus nuchipinnis and Labrisomus cricota in rocky and coral reefs in Northeastern Brazil. In addition, we assessed the time and the predation tactics, employed L. nuchipinnis males and females in tropical rocky reefs of Bahia, northeastern Brazil. The densities were estimated by Interference Visual Census in transects (20m x 2m). Rugosity was measured using the link-chain method. Benthic cover was obtained using photoquadrat method. Additionally, the foraging tactics were observed using the ‘ad libitum’ and ‘focal animal’ methods. The results showed that L. nuchipinnis were significantly more abundant in rocky reefs than in coral reefs, this difference being due to the greater number of adults. L. cricota revealed no difference in abundance among reefs. Overall, the two species were not affected by rugosity, except in coral reefs of Jatiúca, where L. nuchipinnis responded positively and L. cricota negatively. In rocky reefs, the Labrisomus adults didn’t show affinity for specific habitats, while the juveniles exhibited more restricted distribution. In coral reefs, L. nuchipinnis adults and juveniles showed a wide distribution, however, avoided areas with unconsolidated substrates and macroalgae, preferred habitat of L. cricota adults and juveniles. The average time spent in feeding activities was significantly lower in territorial males compared to females, which presents a more active way of life. Seven predation tactics used by L. nuchipinnis were recorded: Follow – nuclear behavior, sit-and- wait, successive bites, predation in the water column, digging substrate and consumption of dead fish, three hitherto unknown last.