Trophic structure of coastal freshwater stream fishes from an Atlantic rainforest: evidence of the importance of protected and forest-covered areas to fish diet

• Published in: Environmental biology of fishes 2018-06, Vol.101 (6), p.933-948
• Main Authors: da Silva Gonçalves, Cristina, de Souza Braga, Francisco Manoel, Casatti, Lilian
• Format: Article
• Language: English
• Subjects: Allochthonous deposits; Animal behavior; Animal Systematics/Taxonomy/Biogeography; Aquatic ecosystems; Aquatic insects; Availability; Biomedical and Life Sciences; Carnivores; Carnivorous animals; Cluster analysis; Coastal streams; Coastal structures; Conservation areas; Detritivores; Detritus; Diet; Ecosystems; Electric fishing; Environment; Fauna; Feeding behavior; Feeding habits; Feeding preferences; Fish; Fish diets; Food; Food availability; Food preferences; Food resources; Food security; Food selection; Food sources; Food supply; Forest protection; Forests; Freshwater; Freshwater & Marine Ecology; Freshwater fish; Freshwater fishes; Functional groups; Inland water environment; Insectivores; Insects; Life Sciences; Nature Conservation; Omnivores; Plant debris; Prey; Rainforests; Riparian forests; Rivers; Seasonal variation; Seasonal variations; Species richness; Stomach content; Trays; Trophic structure; Zoology
• ISSN: 0378-1909; 1573-5133
• DOI: 10.1007/s10641-018-0749-8

The role of riparian forests in the functioning of aquatic ecosystems is well known, and they are recognized as an important food source for riverine fauna. This study investigates the trophic structure of coastal freshwater stream fishes from a large conservation area in an Atlantic rainforest using stomach content and food availability analyses. Four samples were collected from 19 sample sites. Fishes were caught with electrofishing. Prey were sampled with trays, Surber, traps, and electrofishing to evaluate the availability of food resources. The diets of 20 fish species were determined from the stomach contents of 1691 individuals. Terrestrial and aquatic insects and detritus were the most consumed items. Fish diet and prey availability were not seasonally dependent. A cluster analysis showed five trophic functional groups: terrestrial insectivores, aquatic insectivores, detritivores, carnivores, and omnivores. Insectivores predominated in species richness (60%), abundance (47%) and biomass (39%). Allochthonous and autochthonous items were found in similar proportions in the environment; however, allochthonous items were representative for insectivores and detritivores, whereas autochthonous items were important for primarily aquatic insectivores. The preference for certain insects by insectivorous fishes was associated with food selectivity rather than the availability of the resource and demonstrated the strong relationship between feeding behavior and food preference. The absence of seasonal variation in the diets of the fishes was possibly related to the consistent food supply. Our results confirm the role of the forest as a food provider for stream fishes, such as terrestrial insects and plant debris/detritus (also consumed by aquatic insects, which subsequently serve as food for fish), highlighting the importance of conserving the Brazilian Atlantic rainforests.