Eurasian otters modify their trophic niche after the introduction of non-native prey in Mediterranean fresh waters

• Published in: Biological invasions 2014-08, Vol.16 (8), p.1573-1579
• Main Authors: Barrientos, Rafael, Merino-Aguirre, Raquel, Fletcher, David H, Almeida, David
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Applied ecology; Autoecology; Biological and medical sciences; Biomedical and Life Sciences; Cambaridae; Carnivores; Community structure; Conservation, protection and management of environment and wildlife; crayfish; Crustacea; Crustaceans; Developmental Biology; diet; Drought; Ecology; Endemic animals; fish; Fish conservation; Food resources; foraging; Freshwater; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; General aspects; Indigenous species; Introduced species; Invasion Note; Invertebrates; Life Sciences; Lutra lutra; Mammals; Niches; Nonnative species; Parks, reserves, wildlife conservation. Endangered species: population survey and restocking; Plant Sciences; Predation; Prey; Summer; watersheds
• ISSN: 1387-3547; 1573-1464
• DOI: 10.1007/s10530-013-0622-9

Biological invasions are a major driver behind disturbances in freshwater community structure. We investigated how the foraging strategy of the Eurasian otter Lutra lutra (L.) has responded to this change in a Mediterranean catchment of the Iberian Peninsula, over a 30-year time span (1980 vs. 2010). We found that, despite continuing to feed on a considerable amount of native fish, this carnivore has adapted its trophic niche to accommodate non-native species. Prior to the massive introductions of these new food items (1980), otters diversified their diet during the limiting season (i.e. summer drought). However, otters had largely incorporated non-native prey into their diet in 2010, with red-swamp crayfish being their main food resource, especially in the summer. This increased crayfish consumption reflects a narrowing of trophic niche during the summer drought in 2010. We discuss how this heavy specialisation may compromise the conservation of otters and their endemic fish prey.