The effect of water level reduction on the aggressive behavior of Cichlasoma paranaense.

• Grant number: 09/05680-4
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: January 01, 2010
• End date: December 31, 2010
• Field of knowledge: Biological Sciences - Zoology - Animal Behavior
• Principal Investigator: Eliane Gonçalves de Freitas
• Grantee: Angelo Rodrigo Manzotti
• Host Institution: Instituto de Biociências, Letras e Ciências Exatas (IBILCE). Universidade Estadual Paulista (UNESP). Campus de São José do Rio Preto. São José do Rio Preto , SP, Brazil
• Associated research grant: 04/04820-3 - Fauna and flora from forest fragments in the northwest region of São Paulo State: the basis to biodiversity conservational studies, AP.BTA.TEM

Abstract

Destruction of marginal vegetation in aquatic environments can change the physical environment, causing reduction in the water level by evaporation and excessive siltation. Such environmental changes can affect directly the social behavior of territorial fish, by increasing fights due to the reduction of available vertical space. Thus, the aim of this study is to test the effect of water level reduction on the Cichlasoma paranaense's aggressive (and social) behavior. For this, 120 adult males will be addressed to two treatments (n = 20): control group and reduction group. Three matched-sized fish will be grouped for 6 days in each experimental condition. In the control group, fish will be kept in the aquaria with a constant water level (30 cm high; 108 L). In the reduction group, the water level will be reduced 5 cm (108 L) every 24 hours until reaching the minimum level of 15 cm (54 L). The animals of this group will be video-recorded for 15 min, after each reduction and 24 hours later. The frequency of confrontations will be compared between treatments by two-way ANOVA for repeated measures. The hierarchy stability will be analyzed by Kendall concordance test, and the frquency of stable or unstable replicates will be compared between the two treatment by x2 test. This research is part of the thematic project "Fauna and flora of remnant forest fragments in northwestern São Paulo: basis for studies of biodiversity conservation (PROC.04/04820-3)- subproject "fauna of aquatic vertebrates".