Riparian forest subsidises the biomass of fish in a recently formed subtropical reservoir

Riparian forest may represent a key subsidy to aquatic food webs. While most research has been done in running waters, the origin of resources subsidising biomass and the role of riparian coverage in food webs remains largely unstudied in reservoirs. This research evaluated the role of forest riparian zones as food web subsidies in a recently formed reservoir of Ijui River, Brazil. The diet of fish and the origin of carbon and nitrogen fuelling fish biomass was compared between littoral habitats with riparian forests and of open canopy. Sampling for stable isotopes of fish and basal resources and the application of bayesian mixing models showed that most of the fish production originates from terrestrial carbon in this recently formed reservoir. Moreover, an increasing terrestrial support to the biomass was found towards the riparian forest areas (subsidising c.a. 70% vs. around 57% of fish biomass in littoral areas of riparian forest and open canopy, respectively).This study remarked the role of riparian forest areas as energetic subsidises to aquatic ecosystems. Management actions in newly formed reservoirs should include preserving riparian forests to avoid losing natural ecosystem subsidies.

Automated summary

This study evaluated the role of riparian forest areas as food web subsidies in a newly formed reservoir in Brazil. Findings showed that terrestrial carbon was the primary source of fish production in the reservoir, with an increasing terrestrial support towards areas with riparian forests. The study highlighted the importance of preserving riparian forests in newly formed reservoirs to maintain natural ecosystem subsidies.