| Popis: |
In freshwater ecosystems, aquatic insects that ontogenetically shift their habitat from aquatic to terrestrial play vital roles as prey subsidies that move nutrients and energy from aquatic to terrestrial food webs. As a result, these subsidies negatively affect alternative terrestrial prey by enhancing predator density. However, these aquatic insects can also transport contamination to the terrestrial community that is primarily produced in aquatic ecosystems. Which can reduce insectivore abundance and biomass, lower insectivore reproductive success, and increase predation pressure on alternative prey with consequences for aquatic and terrestrial food webs. Motivated by this, here we consider a prey-predator model where the predator consumes contaminated and uncontaminated prey together. We find that, at a high level of contamination, the vulnerability of contaminated prey and predator is determined by predation preference. More specifically, a very low predation preference towards contaminated prey ensures predator persistence, whereas a low, high preference excludes the predator from the system. Interestingly, either contaminated prey or the predator exist at intermediate predation preference due to bi-stability. Furthermore, when there is no contamination in one of the prey, the other prey can not coexist due to apparent competition for a specific range of predation preferences. However, when sufficient contamination exists in one prey, alternative uncontaminated prey coexists. With this, contamination also stabilizes and destabilizes the three species dynamics. Our result also indicates that if the intensity of the contamination in predator reproduction is low, then contaminated prey is more susceptible to the contamination. |
