Diet and niche breadth and overlap in fish communities within the area affected by an Amazonian reservoir (Amapá, Brazil)

Abstract

We investigated the niche breadth and overlap of the fish species occurring in four environments affected by the Coaracy Nunes reservoir, in the Amapá Brazilian State. Seasonal samples of fishes were taken using a standard configuration of gillnets, as well as dragnets, lines, and cast-nets. Five hundred and forty stomach contents, representing 47 fish species were analyzed and quantified. Niche breadth and overlap were estimated using indexes of Levins and Pianka, respectively, while interspecific competition was evaluated using a null model (RA3). ANOVA and the kruskal-Wallis test were used, respectively, to evaluate differences in niche breadth and overlap between areas. The data indicate that the majority of the fish species belong to the piscivore, omnivore, and detritivore guilds. These species have likely colonized the environments due to the availability of suitable feeding resources, and the favorable physical conditions created by the river damming. Overall, few species have ample niches, but most of them are highly specialized. Resources seasonal variation had little effect on the feeding behavior of most species in the study areas. The null models indicated that competition was not a factor determining on community structure.

Feeding ecology of Serrasalmus gouldingi (Characiformes: Serrasalmidae) in the lower Anapu River region, Eastern Amazon, Brazil

“…Some studies have evidence a more generalist diet during flood season (Luz- Agostinho et al 2008;Corrêa et al 2011), while others observed specialized diets during the same season (Sá-Oliveira et al 2014). Our results reinforce the hypothesis that there is no universal pattern in the exploitation of resources, but rather a variety of behavioral strategies related to the environmental characteristics of each system (Novakowski et al 2008).…”

Upstream and downstream responses of fish assemblages to an eastern Amazonian hydroelectric dam

“…The most abundant species in the Upstream Lake and Upstream Channel sites belong to different feeding guilds (omnivores and carnivores), which we hypothesise facilitates their coexistence and dominance at these sites (Sá‐Oliveira et al ., ). The omnivorous H. unimaculatus is considered an opportunistic species with great ecological plasticity in adapting to environmental changes (Petesse, Petrere & Spigolon, ; Gonçalves & Braga, ).…”

“…The vast majority of all individuals sampled ( N = 1819) were successfully identified to a known species, although 7.4% of the individuals and 7.2% of species were morphospecies identified to the level of genus. Species classification into five trophic guilds was based on stomach contents analysis, as described in Sá‐Oliveira, Angelini & Isaac‐Nahum (). Further details of body measurements are presented in Sá‐Oliveira, Angelini & Isaac‐Nahum ().…”

Population parameters of the fish fauna in a long-established Amazonian reservoir (Amapá, Brazil)

“…In addition, the calculation of trophic levels and the classification of the species in feeding guilds provide an essential understanding of resource partitioning and the distribution of niches within a fish assemblage (S a- Oliveira et al, 2014).…”