Feeding strategy and morphology as indicators of habitat use and coexistence of two loricariid fishes from a Brazilian coastal stream

Abstract

We aimed to evaluate the relationship between form and function of two Loricariidae species (Hypostomus punctatus and Parotocinclus maculicauda) from a Neotropical coastal stream. We performed morphological-dietary analysis and discussed their coexistence strategies, as well. We hypothesized that both species use similar food resources according to their morphology but differences in habitat use facilitate their coexistence. In order to test this hypothesis, morphology, diet and habitat use were analyzed for both species. Trophic variance and the Pianka Niche Overlap index were calculated to explore the differences in trophic niche. Correlations between species abundance and water flow were applied to test habitat use. Principal Component Analysis and one Permutational Multivariate Analysis of Variance were applied to test differences between morphology and diet of both species. Morphological-dietary relationships were tested with Mantel test correlations. Total abundance of H. punctatus was higher in the stream channel with higher water flow. The dominant food items were sediment and organic matter for both species, and high trophic niche overlap was revealed. Additionally, morphology did not explain feeding habits for both species. Morphological characteristics were significantly different, especially for intestine length, relative area of the dorsal fin, ventral flattening and mouth attributes. The study site was rich in sand sediment, mud, and clay that are not considered good substrates to the establishment and growing of periphyton, which is an important trophic resource to Loricariidae species. Here, low consumption of periphyton can provide a possible explanation for the feeding similarity and the weak morphological-dietary relationships for both species. Thus, the environmental conditions can be more important for diet composition when compared to the similar and specialized morphology of loricariids.

Trophic level and position of Pterygoplichthys pardalis in Ciliwung River (Jakarta, Indonesia) ecosystem based on the gut content analysis

“…Plecos consume phytoplankton, zooplankton and detritus as its main (56.39%), supplementary (36.94%) and additional (6.67%) diets. These results are similar to those obtained in the previous studies which stated that pleco's main diet is Bacillariophyta, Chlorophyta, while Cyanophyta and Eugleophyta, Xanthophyta, Crustacea are additional diets (de Oliveira and Isaac 2013; Tisasari et al 2016;Manna et al 2020). The dissimilarities in the feeding habits of fishes tend to occur as a result of the differences in the availability of food utilized in its natural habitat.…”

“…Generally, the Bacillariophyta group is found in sediments and substrates of both mild and strong currents (Genkal and Yarushina 2014;Genkal and Yarushina 2016). This is consistent with the feeding behavior of P. pardalis as a bottom feeder fish, because this group is a type of phytoplankton that is widely attached to sediments or substrates (Lujan et al 2012;Genkal and Yarushina 2014;Genkal and Yarushina, 2016;Manna et al 2020). The type of diet consumed by P. pardalis determines the feeding habits in the Ciliwung River.…”

“…However, the availability of food resources is one of the factors that influence the existence of fishes. Previous studies have also established that a correlation exists between the structure of the digestive apparatus and the feeding habits of fishes (Pereira et al 2016;Lopez-Rodriguez et al 2019;Manna et al 2020).…”

“…According to Effendi, fish's preference for diet is relative (Effendie 1997). Additionally, the distribution of food organisms, availability of natural diet, and physical conditions tend to influence their feeding habits (Garcia et al 2018;Wei et al 2018;Manna et al 2020). Therefore, greater availability of food resources in the invaded habitats provided conditions that are conducive for the establishment of non-native species (Delariva and Agostinho 2001;Pound et al 2011;Garcia et al 2018).…”

“…Generally, members of the Loricariidae feed on diets consisting of plant fragment, zooplankton, arthropods, chlorophytes, bacillariophytes, cyanobacteria and cyanobacteria (Mazzoni et al 2010;de Oliveira and Isaac 2013;Samat, et al 2016;Tisasari et al 2016;Manna et al 2020). Pterygoplichthys sp.…”