Trophic level, food chain length and omnivory in the Paraná River: a food web model approach in a floodplain river system

摘要: To determine the mean trophic level and food chain length to quantify omnivory in a floodplain lake of Middle Parana River, we constructed web model based on available data. Because proper selection basal resources is essential, performed stepwise decide which sources include model. We estimated level, using binary (non-weighted links) weighted (trophic links stable isotopes). Model excluded macrophytes as relevant for this lake. In general, were relatively even, leading similar estimations both webs. Food length, however, was higher web, caused by strong link top predators with lower-trophic prey ecosystem. Overall, estimate River not particularly high, despite high productivity size suggest that periodical hydrological fluctuations large rivers could be major factor precluding occurrence long chains.