Divergence in energy sources for Prochilodus lineatus (Characiformes: Prochilodontidae) in Neotropical floodplains

Abstract

The stable carbon isotopic variability and the contributions of autochthonous (sediment microbial biomass, phytoplankton, and periphyton) and allochthonous (soil microbial biomass) sources available to the detritivorous fish Prochilodus lineatus were investigated in three environments of the floodplain of the Upper Paraná River. The isotopic composition of carbon sources and fish varied significantly among the studied environments. The autochthonous resources, represented by the phytoplankton, were the most assimilated by the species, followed by periphyton and sediment microbial biomass. The species used the sources differently in each environment. This study suggests that the inherent characteristics of this area, as well as the size of the watershed, the dry season, anthropogenic actions, and phytoplankton productivity, favor the use of autochthonous resources by the species studied. Therefore, studies in the floodplain should employ an eco-hydrological approach that quantifies the magnitude of energy subsidies, as well as an access route to consumers, knowledge about the selectivity of detritivorous species and the effects of different land uses.

Biogeochemical multi‐tag approach reveals the habitat use of a large‐scale migratory fish through a fluvio‐estuarine system

“…Our results suggest that the relative proportion of C sources for the MPR fish varies with respect to that found for the HPR. Nevertheless, the similarity found in the δ 13 C values estimated from the fish tissues with the C3 photosynthetic pathway (À32.0‰ and À22.0‰) (Boutton, Archer, Midwood, Zitzer, & Bol, 1998) indicates the predominance of these carbon sources for P. lineatus in the sampling area, coinciding with what was described in previous studies for the rest of the basin (Benedito et al, 2018;Lopes et al, 2007;Marchese et al, 2014).…”

“…The SOM had δ 13 C values ranging in concordance with those reported for primary producers using C 3 photosynthetic pathway (phytoplanktonic and periphytic algae) and formerly informed for organic matter in the La Plata Basin (Benedito, Santana, & Werth, 2018;Tudurí, Bergamino, Violante, Cavallotto, & García-Rodríguez, 2018). The depleted values registered in the HPR could probably be related to the input of allochthonous organic matter that comes with heavier C sediments from C 4 plants, as it was previously reported in the Itaipú Reservoir (Benedito et al, 2018;Lopes, Benedito-Cecílio, Martinelli, & Moreira, 2007). Unlike δ 13 C, the δ 15 N organic matter composition from the basin has scarcely been studied (Lopes et al, 2007;Marchese et al, 2014).…”

“…(1) autochthonous material (e.g., biomass resulting from primary production by attached algae and phytoplankton) or (2) allochthonous inputs from the terrestrial part of the catchment (Gimenes, Takeda, & Benedito, 2012). The SOM had δ 13 C values ranging in concordance with those reported for primary producers using C 3 photosynthetic pathway (phytoplanktonic and periphytic algae) and formerly informed for organic matter in the La Plata Basin (Benedito, Santana, & Werth, 2018;Tudurí, Bergamino, Violante, Cavallotto, & García-Rodríguez, 2018). The depleted values registered in the HPR could probably be related to the input of allochthonous organic matter that comes with heavier C sediments from C 4 plants, as it was previously reported in the Itaipú Reservoir (Benedito et al, 2018;Lopes, Benedito-Cecílio, Martinelli, & Moreira, 2007).…”

“…Prochilodus lineatus is a detritivore fish that consumes a mixture of material composed of phytoplankton, periphyton, terrestrial detritus, and microorganisms (Smoot & Findlay, 2010). Previous isotope studies revealed that the main carbon sources used by P. lineatus are autochthonous, and the isotopic composition of fish varied significantly among the environments according to their inherent characteristics (Benedito et al, 2018). To interpret δ 13 C and δ 15 N results, all tissue values were plotted against SOM values and grouped by sampling site as an exploratory approach to the isotopic space (Figure 2).…”

Do fish isotopic niches change in an Amazon floodplain lake over the hydrological regime?

“…The study of Benedito et al. (2018) in three areas of the Paraná river floodplain (Baía, Paraná and Ivinheima rivers) during the falling water season indicates that the detritivorous species of the genus Prochilous have a diet composed of a mixture of autochthonous phytoplankton, periphyton detritus and allochthonous organic matter. These authors reported higher relative importance, more than 88%, of autochthonous resources for P. lineatus in the Baía and Parana rivers, possibly due to higher primary productivity.…”