Resource use by omnivorous fish: Effects of biotic and abiotic factors on key ecological aspects of individuals

Abstract

Intraspecific variations in the use of resources result from the influence of factors related to individuals and the environment in which they live. Knowing which factors and how they influence the choice of a given resource allows us to understand the different ecological roles of individuals in a population (Singer & Bernays, 2003). This adaptive strategy maximises energy production and optimises the growth and reproductive success of individuals (Araújo et al., 2011;

Data-Driven System Dynamics Model for Simulating Water Quantity and Quality in Peri-Urban Streams

“…Several studies highlighted that urbanization leads to increased and highly dynamic loads of more labile dissolved organic matter fraction and enhanced heterotrophic respiration [93,94], which will constitute a challenge in peri-urban settings considering the myriad of The results from the stream water quality simulation highlight important seasonal variations of stream water temperature that may be amplified in peri-urban settings. Notably, here, temperatures above 21 degrees Celsius (local threshold value) are estimated during the summer season, with potential adverse effects in terms of DO concentration (due to decrease in DO saturation) and on the stream biota [91]. The model indicates a limited stream thermal inertia (driven by the shallow depth and fast equilibrium rate with the atmosphere, not shown), resulting in the stream water temperature being strongly correlated to the air temperature as the main explanation.…”

DIET COMPOSITION, CONDITION FACTOR AND INTESTINAL COEFFICIENT OF THE FISH Astyanax lineatus REFLECT THE ANTHROPOGENIC EFFECTS ON STREAMS IN CENTRAL BRAZIL

“…Likewise, Oliveira & Bennemann (2005) found that in urban environments with different levels of disturbance, other Characidae fish presented a shift in their diet and fed on unusual resources. Fernando & Súarez (2020), when studying A. lineatus, found that the diet composition was directly affected by environmental variables, such as vegetation cover, streamflow, and dissolved oxygen. In the present study, the proportion of allochthonous items in the A. lineatus diet was lower when the vegetation cover and stream flow were reduced.…”

“…Therefore, it is possible that human actions on the Cabaça stream ("degraded habitat") margins are responsible for some of the alterations in A. lineatus diet composition. The Cabaça stream also receives a discharge of urban and industrial effluents, food scraps, plastic, and other types of detritus from human activity, known to cause fish to feed on unusual food resources (McClelland & Valiela 1998, Costa & Zalmon 2017, Fernando & Súarez 2020.…”

“…The sampling area of the Cabaça stream is located inside the Private Natural Heritage Reserve (RPPN), which belongs to the Universidade Federal de Mato Grosso do Sul, and it covers 30% of the total length in the fi nal stretch of the stream (personal observation). Native riparian vegetation has been mostly suppressed along the stream, which directly impacts the entry of light into the stream (Fernando & Súarez 2020). Moreover, the quality of the water is often altered, primarily due to the urban effl uents that increase concentrations of nutrients, metals, bacteria, organic matter, and suspended materials (Silva 2010).…”

“…It can be found in urban areas with higher levels of perturbation and in less degraded natural areas (Casatti et al 2010). Given the increasing anthropogenic alterations of aquatic ecosystems and their substantial impacts on fishes' survival, studies addressing fish diet and its consequent effects are becoming increasingly important (Fernando & Súarez 2020) (Ceneviva-Bastos & Casatti 2007.…”