A dinâmica entre peixes-predadores e invertebrados-presa em diferentes cenários ambientais.

• Autor(a) principal: Figueiredo, Bruno Renaly Souza
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Estadual de Maringá (RI-UEM)
• Texto Completo: http://repositorio.uem.br:8080/jspui/handle/1/4949
• topic: Peixes de água doce; Invertebrados de água doce; Interação predador-presa; Comportamento antipredatório; Ecologia de água doce; Predação (Ecologia); Insetos aquáticos; Comportamento animal; Heterogeneidade de habitat; Experimentação animal; Brasil.; Predation; Predator-prey interaction; Animal behaviour; Aquatic insects; Habitat heterogeneity; Animal experimentation; Brazil.; Ciências Biológicas; Ecologia

The survival of a given prey is primarily determined by their capacity to recognize and respond to the current predation threat degree. Such prey responses could be more or less effective according to environmental characteristics, such as visibility conditions and temperature. However, the evolutionary time of co-occurrence between predators and prey could also be a crucial factor to shape the appropriated prey response to predator strike. Fluctuations in environmental conditions are expected to be more frequent as a result from global warming, which has been catalysed by human being?s actions. Therefore, it is quite timely investigate the influence of environmental shifts on the outcomes of predator-prey encounters. Here, we used an experimental approach to observe the prey capture efficiency of fish-predators and anti-predator behaviour of some groups of invertebrates (aquatic insects and amphipods) in distinct ecological scenarios of underwater visibility, water temperature and presence/absence of refuge (provided by aquatic macrophyte). Also, we investigated the consequences of species invasions for the interaction between predators and preys on two perspectives: after the establishment of a non-native aquatic plant (Hydrilla verticallata), and after the introduction of a non-native piscivorous fish. In reduced water transparency, fish consumed fewer invertebrates than in clear water, but the efficiency in capturing invertebrates of mesopredators was strongly reduced when top-predator was present and water transparency low. Therefore, the mere presence of a top predator has potential to increase invertebrate survive, but underwater visibility is impaired mesopredator do not know the exact top predator location, then they tend to reduce their mobility to decrease the likelihood to be eaten, such response can concomitantly limits the mesopredator predatory potential. Despite of the literature supports the positive relation between water temperature and the distance travelled by predators, which often results in better feeding efficiency in warmer waters, Gymnogeophagus terrapurpura showed similar amount of amphipods (Hyalella curvispina) consumed in four different water temperature (19.2; 22.2; 25.2 and 27ºC). In contrast, amphipods show more conspicuous anti-predator behaviour at 27ºC. In addition, we found that non-native aquatic plants are recognized as a safe habitat and used by prey fish as refuge in a similar proportion than native plants are. We also found that the predation pressure performed by Astyanax altiparanae on one pelagic invertebrate population (Daphnia magna) was extremely high in treatments with the native piscivorous Hoplias aff. malabaricus. However, in treatments with the non-native Astronotus crassipinnis, the survival of pelagic invertebrates was proportional to benthic prey population (Chironomus sancticaroli). Therefore, the introduction of a piscivorous fish has potential to change the energy pathway in the entire ecosystem. Simulating observed and predicted ecological scenarios, even in microcosm, allow us to understand the main effect of a given variable on predation in the wild, and possible interactive effect among multiple variables. Knowing the factors that influence the predation can help ecologists to propose management project for fish and invertebrates species.