Habitat loss and discontinuity as drivers of habitat fragmentation: The role of contamination and connectivity of habitats.

Abstract

Habitat discontinuity of aquatic environments is a serious problem that might hamper the different activities performed by organisms. When combined with contamination, the consequences for the population's dynamics might be exacerbated, particularly regarding foraging activity. Therefore, the aim of this study was to evaluate the combined effects of habitat discontinuity and contamination on the foraging behavior by zebrafish (Danio rerio) and on their ability to explore heterogeneous landscapes. The organisms were exposed to three different scenarios of contamination (0, 0.5 and 25 μg L^-1 of Cu) and habitat discontinuity (zero, low and high), using the Heterogeneous Multi-Habitat Assay System (HeMHAS). Generalized Bayesian linear models were used to analyze the data and evidence ratios (ER) were used to test the hypotheses. As results, both high levels of contamination and habitat discontinuity had significant effects on the probability of organisms to reach food (ER = 111.8 and > 1,000, respectively), the time taken to reach food (ER = 532.22 and > 1000, respectively) and the time spent in each compartment (ER = 614.4 and > 1000 for contamination and the number of connections available, respectively). As conclusion, the habitat fragmentation as a consequence of contamination and discontinuity affected the probability of fish to reach food and the time spent to reach it. This could lead to additional energy budget with serious consequences for population dynamics. Also, the HeMHAS demonstrated its suitability to assess the role of the contamination and habitat connectivity stressors in the spatial distribution and habitat selection response.