Overlap of dietary niche and electivity of three shrimp species (Crustacea, Decapoda) in a tropical coastal lagoon (Rio de Janeiro, Brazil)

Abstract

ABSTRACT. Three species of shrimp, Farfantepenaeus brasiliensis (Latreille, 1817), F. paulensis (Pérez-Farfante, 1967) (Penaeidae) and Macrobrachium acanthurus (Wiegmann, 1836) (Palaemonidae) were sampled at the Imboassica lagoon (Rio de Janeiro State, Brazil), in order to estimate the overlap of dietary niches and electivity of their prey, through the analysis of the fauna associated with the macroalgae Chara and of the benthic fauna on the sediment. The overlap of dietary niches was estimated using five indexes. A total of 495 F. brasiliensis, 131 F. paulensis and 102 M. acanthurus stomachs were examined. The results of the different indexes of niche overlap exhibited the same general trend in the three species, indicating a high degree of homogeneity in the diet of the two species of Penaeidae (between 75 and 100%) and a smaller overlap between each Penaeidae species and M. acanthurus (between 23 and 68%). The species presented selective predation, with differences in the two studied habitats. The results show that the three species are omnivorous, with a varied diet including components of benthic macrofauna and those associated with the macroalgae Chara, plant fragments and detritus, and that there are good conditions in the Imboassica lagoon for the development of these species.

Do climate variables and human density affect Achatina fulica (Bowditch) (Gastropoda: Pulmonata) shell length, total weight and condition factor?

“…Whatever the strongest explanation for A. fulica growth, our results provide evidence that measures of climate and human density affects the shell length and total weight of Achatina fulica. Furthermore, the condition factor reflects the snail's welfare and responds to physiological changes, especially during the aestivation stage and periods of low moisture (Vinci et al, 1998;Albertoni et al, 2003). Even though in the study area there were no severe changes in mean temperature and humidity during our study, our results indicated that climatic variables and human density explain great proportions of variance of the condition factor.…”

“…This factor reflects changes in the animal's physiology, especially during aestivation, and has also been broadly used to estimate mean weight from a known length and to calculate the index of physical condition of populations (Beyer, 1987;Vinci, 1998;Bolger and Connoly, 1989;Albertoni et al, 2003). Furthermore, the condition factor is very useful to evaluate habitat quality and may contribute to assess population welfare (Le Cren, 1965;Ricker, 1975;Bolger and Connoly, 1989).…”

Reproductive biology of Macrobrachium amazonicum (Heller, 1862) (Decapoda: Palaemonidae) in a reservoir situated in Minas Gerais State, southeastern Brazil

“…They represent an important group not only by the ecological aspect, because they form an important link between producers and consumers of higher trophic levels (Albertoni et al, 2003a(Albertoni et al, , 2003b, but also by economic and social aspects, especially for communities that use them as fishery resource and food (Valenti et al, 1989).…”

Chironomidae larvae (Diptera) of Neotropical floodplain: overlap niche in different habitats

“…The interactions of species may lead to trophic niche overlap, important to quantify how two or more species overlap in the use of food resources (Albertoni et al, 2003;Mokany et al, 2008). The competition between the larvae of Chironomidae can lead to a niche overlap and even limit species with similarity of niches.…”