Variation in Neotropical river otter (Lontra longicaudis) diet: Effects of an invasive prey species

Abstract

Predation is one of the main barriers that exotic species may face in newly colonized areas and may help stop or control the potential negative impacts of invasive species in the environment. We evaluated if the consumption of an invasive prey (armored catfish: Pterygoplichtys sp.) affects the dietary niche breadth and trophic level of a native predator (Neotropical river otter: Lontra longicaudis) in northern Guatemala. We examined otter scats from three rivers: two where the invasive armored catfish occurred and one without the invasive fish. Samples were collected two and seven years after the first report of the catfish in the area. We performed gross scat analysis and stable isotope analyses of nitrogen and carbon of fecal matter. Where the invasive armored catfish occurred, it was the main prey item for L. longicaudis. Particularly in the river outside of protected areas seven years after the first report of the catfish, where it accounted for 49% of the otter diet. Concordance was found between the two techniques to estimate dietary niche breadth and trophic level. The dietary niche breath of otters was narrower seven years after the invasion in comparison to two years after the invasion in both invaded rivers, but the extent of the reduction was lesser inside the protected area. Finally, the trophic level of otters also showed a reduction related to the occurrence of the armored catfish in their diet.

An update of the invasive Pterygoplichthys Gill, 1858 (Actinopterygii, Loricariidae) in Guatemala: new records and notes on its interactions with the local fauna

“…Knowing these interactions is highly important in discussions about the management plans that should be initiated regarding plecos in Guatemala. The effects of plecos are already being noticed, as the niche breadth and the trophic level of the Neotropical Otter have been altered (Juarez-Sanchez et al 2019) and this should be assessed with the additional species that we report.…”

Distribution and habitat use intensity of the Neotropical Otter (Lontra longicaudis) in a Colombian hydroelectric dam

“…Faeces counting has been a traditional non-invasive method used in numerous investigations because they are easily detected in the natural environment (Kasper, Bastazini, Salvi, & Grillo, 2008;Rheingantz et al, 2011;Franco et al, 2013;Biffi & Williams, 2017;Grajales-García et al, 2019). Faeces are generally deposited in conspicuous places along the shore of water bodies and can be clearly differentiated from those dropped by other carnivores (Delibes-Mateos, Díaz-Ruiz, Caro, & Ferreras, 2014;Juarez-Sanchez, Blake, & Hellgren, 2019). However, the detection probability of faeces decreases in prolonged rains periods since they can be easily rinsedoff (Medina-Vogel & González-Lagos, 2008;Delibes-Mateos et al 2014).…”

Expanding the invasion toolbox: including stable isotope analysis in risk assessment

“…It is often used to assess the impacts of introduced species on other taxa in term of predation (Haubrock et al 2019a;Gaiotto et al 2020;Oe et al 2020) and competition with native (Balzani et al 2016) and other alien species (Balzani et al 2020;Haubrock et al 2020a). Moreover, it can be used to reveal the role of new alien prey in the diet of resident predators (Juarez-Sanchez et al 2019;Stellati et al 2019), compare trophic levels between introduced and native populations of invasive species (Balzani et al 2021), as well as to disentangle trophic relationships among alien species in invaded communities (Haubrock et al 2019a;Bissattini et al 2021). Finally, SIA can be used to identify links between terrestrial and aquatic environments and depict changes in either one following alterations in the other (Gregs et al 2014).…”