Effects of an alien competitor on feeding and aggressive behavior

Abstract

Invasive species are one of the major threats to native ecosystems and biodiversity. In Brazil, the Nile tilapia Oreochromis niloticus is one of the most common invasive fish species that has been spreading through the watersheds of the country. Invasive fish can negatively impact the community trophic interactions, native species abundance, and interspecific interactions due to their higher competition capacity and territoriality. The pearl cichlid Geophagus brasiliensis is a native species with a wide geographical distribution in Brazil, which presents an overlapping niche with Nile tilapia. For this reason, the pearl cichlid has been suffering a decrease in its abundance. Despite that, little is known about the effects of interspecific competition in pearl cichlid feeding and aggressive behavior in the presence of this alien species. The present study aims to evaluate the effects of the interspecific competition of an alien species (Nile tilapia) in feeding and aggressive behavior of the pearl cichlid Geophagus brasiliensis. Recent studies have already demonstrated that an alien competitor can modify many native species' behavior. To understand how the presence of an alien species can alter the aggressiveness and the feeding behavior, we will stimulate the pearl cichlid with chemical and visual stimuli of different sources: allopatric competitor (Nile tilapia), sympatric competitor (curimbatá), conspecific (pearl cichlid) and sympatric non-competitor (lambari). Therefore, we will evaluate the feeding behavior (feeding intake and ingestion latency) and aggressiveness (latency and agonistic interactions).