Habitat complexity does not influence prey consumption in an experimental three-level trophic chain

Abstract

Habitat complexity influences species diversity and regulates trophic interactions, mostly by increasing resource partitioning within habitats and providing refuge for prey. The influence of habitat complexity on more than two trophic levels is not well understood, mainly because behavioral modifications of prey and predator may influence the outcome of trophic interactions. Thus, we conducted a two-factor experiment with a three-level trophic chain: a piscivorous fish [Hoplerythrinus unitaeniatus (Spix & Agassiz 1829)], an invertivorous fish (Moenkhausia forestii Benine, Mariguela & C. de Oliveira, 2009) and an aquatic macroinvertebrate (Chironomidae larvae). We measured prey consumption in low, intermediate and high habitat complexity, provided by submerged macrophyte densities, in the presence and the absence of the piscivore, intending to test the hypothesis that higher habitat complexities decrease predators foraging success in different trophic levels. We calculated the percentage of consumed prey in all treatment combinations. There was no significant effect of habitat complexity on prey consumption for neither the piscivorous nor the invertivorous fish, but a positive correlation was found between the percentages of consumed prey by both the piscivore and the invertivore. Observed modifications in the foraging behavior of the piscivore may have resulted in similar prey consumptions in low and high macrophyte densities. Moreover, more active M. forestii could have suffered a higher predation pressure by H. unitaeniatus, resulting in the positive correlation found. We conclude that behavior patterns in different habitat complexities possibly influenced predation rates in the three experimental trophic levels.

Acute Ecotoxicity of Exposure to Sugarcane Ashes on the Behaviour of Predator and Prey Fish Species

“…Agostinho et al, 2007). H. unitaeniatus is a voracious piscivore with a high activity level (Granzotti et al, 2018;Lopes et al, 2021), which allows us to assess its predatory behaviour. Moreover, although Gonino et al (2019a) have revealed the lethal effects of SCA at a concentration of 1981.74 mg/L for M. forestii, no information is available on non-lethal effects of sublethal concentrations for either H. unitaeniatus or M. forestii.…”

“…2 Mean and standard error of Hoplerythrinus unitaeniatus behavioural traits measured in frequency (%) and duration (minutes) under treatments of fish exposure to sublethal con-centrations of sugarcane ashes (SCA) (0.8 g L −1 of SCA for 24 h) (No SCA, no SCA addition; Prey SCA, only prey exposed to SCA; Predator-Prey SCA, predator and prey exposed to SCA) of pollutants on the behaviour of aquatic organisms is individual-dependent (Blake & Gabor, 2014;Sih et al, 2004). For H. unitaeniatus, previous experimental studies have demonstrated individual differences in the strategy to capture its prey (Granzotti et al, 2018). Individuals within populations can differ in a wide spectrum of traits, including the behavioural ones (Dingemanse et al, Table 2 Analysis of deviance table (type II test) of fixed variables: treatments of fish exposure to sublethal concentrations of SCA (three levels: "no SCA addition", "prey SCA exposition", "predator and prey SCA exposition") and time (three levels: "after 1 h", "after 12 h" and "after 24 h" of co-occurrence between predator and prey) from generalized mixed models on the percentage of prey consumed (i.e.…”