Diet and feeding selectivity of a benthivorous fish in streams: responses to the effects of urbanization

Abstract

This study evaluated the diet and feeding selectivity of the catfish Imparfinis mirini in streams with different degrees of urbanization and the effect of rainfall on the availability of prey. The diet was based especially on Chironomidae and Trichoptera. Significant spatial differences in diet were found between the streams; the diet of the fish was similar in the rural and peri-urban streams, and differed from that in the urban stream. Seasonality was an unimportant factor affecting the species' diet, which did not differ significantly between the rainy and dry periods in any of the streams. Fish from the urban stream fed more according to what was available in the environment, while fish from the peri-urban and rural streams showed higher degrees of selectivity. The results indicate that environmental conditions influenced the diet and prey selection of this species in response to the differences in diversity and abundance of the food organisms. They indicate that trophic studies of benthivorous fishes, such as I. mirini, may represent an alternative way to assess human effects on streams.

<b>Diet of <i>Poecilia reticulata</i> Peters, 1959 in streams from Paraná River basin: influence of the urbanization

“…This occurs likely because the population fed on a more balanced manner, consuming detritus and Chironomidae in both hydrological periods. These results were contrary to our expectations that the US is subject to more pronounced changes during the rains, affecting food resources to fishes (Kikuchi & Uieda, 1998;Fogaça et al, 2013;Tófoli et al, 2013). The US is the most degraded as a function of receiving a large load of urban pollution, but in this environment, the species consumed a high amount of Chironomidae.…”

“…According to Cunico et al (2012), P. reticulata was the most abundant species in rural and urban streams (in the same sub-basin of this study), representing respectively 97% to 100% of the fish fauna captured. Additionally, it is important to highlight that Imparfinis mirini (Haseman, 1911), a small bodied fish which also forage the substrate and were captured in the same sample sites of this study, consumed a very low proportion of detritus related to the benthonic organisms (Tófoli et al, 2013). It shows that the high quality food (i.e.…”

“…Thus, it is possible that P. reticulata has found some punctual patches containing this dipteran adhered to vegetation, which facilitated the capture, considering that these larvae were rare in the environment (Janet Higuti, unpublished data). On the other hand, Coleoptera was the most abundant organism on this stream (Tófoli et al, 2013), but not the most consumed by this population.…”

“…caused by rainfall) changes the macroinvertebrates community, affecting the diet of these species. Thus, studies regarding the trophic ecology of populations inhabiting these habitats can be an indirect way to assess impacts on aquatic environments (Tófoli, Alves, Higuti, Cunico, & Hahn, 2013).…”

Diet of characin,Brycon falcatus(Muller and Troschel, 1844) in the Amazon Basin: a case study on an attractant for fish in the Teles Pires River

“…The natural fish diet in the control river was the most diverse, with this diversity of items decreasing in those rivers where attractants are used. This change was also observed in a study performed in streams in southeastern Brazil, in which the diet of the benthivorous species Imparfinis mirini exhibited a lower diversity of items in streams with a high degree of urbanization (Tófoli et al., ). The human impact on food consumed by fish was also analyzed in a stream in southeastern Brazil, indicating a change in the diversity of items in the fish assemblage (Oliveira and Bennemann, ).…”