The diet of otters (Lutra lutra) on the Agri river system, one of the most important presence sites in Italy: a molecular approach

Abstract

Background The Eurasian otter (Lutra lutra) underwent a strong decline in large areas of the Central-Western part of its distribution range, during the second half of the twentieth century. In Italy, only residual fragmented nuclei survive in the Central-Southern part of the peninsula. Nowadays, the otter is one of the most endangered mammals in Italy, and increasing the knowledge about the ecology of this species is a key step in defining fitting management strategies. Here we provide information about the diet of otter on the Agri river system, one of the most important presence sites in Italy, to understand both the species’ food requirements and the impact on fish communities. Methods DNA metabarcoding and High Throughput Sequencing were used on DNA extracted from spraints. We amplified DNA with a primer set for vertebrates, focusing efforts on the bulk of the otter’s diet (fishes and amphibians). Results Our findings showed that the diet of the otter was dominated by cyprinids (97.77%, and 99.14% of fishes), while amphibians represented 0.85% of the sequences analyzed. Results are in general accordance with previous studies based on morphological characterization; however, molecular analyses allow the resolving of some morphological uncertainties. Although the study area offers a very wide range of available prey, the diet of the otters shows marked selectivity. We highlighted a variation in prey consumed, in accordance with the typology of water system (i.e., river, lake, tributary). Some of the preys found in the diet were alien species introduced by man for sport fishing. Our findings could help define strategies useful for the conservation of the otter population in Southern Italy, suggesting management actions directed at avoiding fish community alterations through illegal stockings without severe controls on their taxonomic status. These introductions could result in a general reduction in the diversity of the otter’s preys, affecting its predatory behavior.

Using DNA metabarcoding to investigate diet and niche partitioning in the native European otter (Lutra lutra) and invasive American mink (Neovison vison)

“…Our results are also in agreement with faecal DNA metabarcoding studies of otter diet. Both Buglione et al (2020) and Martínez-Abraín et al (2020) found fish were the primary food resource for otters, followed by amphibians. Specifically, Cyprinidae, Gobidae, Salmonidae and Percidae were the predominant prey taxa.…”

“…As such, DNA metabarcoding provides species resolution data at greater spatiotemporal scales for the vast majority of prey items, regardless of prey size, type and integrity or lack of hard components (Oehm et al 2011;Pompanon et al 2012;McInnes et al 2017;Forin-Wiart et al 2018;Traugott et al 2020). Since its inception, DNA metabarcoding has been employed to assess the diet of various mammalian predators (Shehzad et al 2012a(Shehzad et al , 2012b; De Barba et al 2014;Berry et al 2017;Gosselin et al 2017;Forin-Wiart et al 2018;Robeson et al 2018;Schwarz et al 2018) and recent small-scale studies have shown its potential for European otter (hereafter otter) diet analysis (Buglione et al 2020;Martínez-Abraín et al 2020).…”

Unraveling the dietary diversity of Neotropical top predators using scat DNA metabarcoding: A case study on the elusive Giant Otter

“…However, its use has remained marginal (<10% of the scat-based carnivore diet analyses, Monterroso et al, 2019) and it has rarely been applied to top predators in tropical ecosystems (but see Havmøller et al, 2020) despite promising results on herbivores (Alberdi et al, 2019;Hibert et al, 2011;Mallott et al, 2018;Quéméré et al, 2013), hematophagous arthropods (Rodgers et al, 2017), or bats (Bohmann et al, 2018). This lack of studies on top predators in tropical compared to temperate areas (Deagle et al, 2010 on little penguins; Shehzad et al, 2012 on leopard cats;Kumari et al, 2019 andBuglione et al, 2020 on Eurasian otters) may be partly attributed to specific methodological issues. First, the efficiency of sDNA metabarcoding is highly dependent on the accuracy and completeness of reference DNA barcode databases (Alberdi et al, 2019;Zinger et al, 2020).…”

Using DNA metabarcoding to investigate diet and niche partitioning in the native European otter (Lutra lutra) and invasive American mink (Neovison vison)

“…As such, DNA metabarcoding provides species resolution data at greater spatiotemporal scales for the vast majority of prey items, regardless of prey size, type, and integrity or lack of hard components (Oehm et al 2011; Pompanon et al 2012; McInnes et al 2017; Forin-Wiart et al 2018; Traugott et al 2020). Since its inception, DNA metabarcoding has been employed to assess the diet of various mammalian predators (Shehzad et al 2012a, 2012b; De Barba et al 2014; Berry et al 2017; Gosselin et al 2017; Forin-Wiart et al 2018; Robeson et al 2018; Schwarz et al 2018), and recent small-scale studies have shown its potential for European otter (hereafter otter) diet analysis (Buglione et al 2020; Martínez-Abraín et al 2020).…”

“…2018), and recent small-scale studies have shown its potential for European otter (hereafter otter) diet analysis (Buglione et al 2020;Martínez-Abraín et al 2020).…”