Short-Term Interactive Effects of Experimental Heat Waves and Turbidity Pulses on the Foraging Success of a Subtropical Invertivorous Fish

Figueiredo Figueiredo,Mormul Mormul,Benedito Benedito,Meerhoff Meerhoff,Mello Mello,Calvo Calvo,López-Rodríguez López-Rodríguez

doi:10.3390/w11102109

Abstract

Sudden increases in temperature and turbidity in aquatic ecosystems are expected for different regions in the future, as a result of the more frequent extreme climatic events that are predicted. The consequences of these abrupt changes in the outcomes of predator–prey interactions are unknown. Here, we tested the effects of a heat wave and a turbidity pulse on the foraging success of a subtropical cichlid fish (Gymnogeophagus terrapurpura) on amphipods (Hyalella curvispina). We carried out a short-term experiment combining treatments of turbidity (3 and 100 nephelometric turbidity units [NTU]) and water temperature (19.2, 22.2, 25.2 and 27.0 °C), considering potential differences given by fish length. Changes in water temperature did not promote significant changes in prey consumption. Higher turbidity, in contrast, decreased prey consumption. Also, we found that fish with different body lengths consumed a similar amount of prey under clear waters, but, in turbid waters, bigger individuals were more efficient than the smaller individuals. This finding is an empirical demonstration that the effect of increased turbidity on predation rate depends upon predator body size, and it suggests that bigger body sizes may help overcome turbidity-associated limitations in finding and capturing prey. Our short-term results suggest that, if turbidity pulses and heat waves become more frequent in the future, the outcome of fish–invertebrate interaction can be affected by local characteristics such as fish population size distribution.

Highlights

Climate change scenarios and models make varied predictions for different locations around the world
In our short-term experimental simulation of two environmental scenarios predicted as direct and indirect results of climate change, we found no clear effects of heat waves nor of the interaction between heat waves and turbidity pulses on the prey consumption by a subtropical cichlid fish
The sudden increase in turbidity had negative consequences on the foraging success of this fish species, but with different magnitudes depending on their body length

Summary

Introduction

Climate change scenarios and models make varied predictions for different locations around the world. Increases in the average temperature and in the frequency of extreme temperatures and rainfall events are expected in many regions [1,2], and in the tropical and subtropical regions [3,4] Such environmental changes may affect several processes at different spatial, temporal and biological scales [5], including the predator–prey encounter and predation rates [6]. It has been shown that while small changes in water temperature have little or no impact on the predator ability to encounter their prey [11,16], heat waves can promote massive prey consumption, destabilising the consumer-resource interactions across trophic levels [17] Such as aquatic invertebrates, increases in water temperature may change their survival rate depending on the balance between the temperature-dependent escape speed of the prey and the temperature-dependent attack speed of the predator [16]

Methods

Results

Conclusion