Otterly delicious: Spatiotemporal variation in the diet of a recovering
population of Eurasian otters (Lutra lutra) revealed through DNA
metabarcoding and morphological analysis of prey remains
Abstract
Eurasian otters are apex predators of freshwater ecosystems and a
recovering species across much of their European range; investigating
the dietary variation of this predator over time and space therefore
provides opportunities to identify changes in freshwater trophic
interactions and factors influencing the conservation of otter
populations. Here we sampled faeces from 300 dead otters across England
and Wales between 2007 and 2016, conducting both morphological analysis
of prey remains and dietary DNA metabarcoding. Comparison of these
methods showed that greater taxonomic resolution and breadth could be
achieved using DNA metabarcoding but combining data from both
methodologies gave the most comprehensive dietary description. All otter
demographics exploited a broad range of taxa and variation primarily
reflected changes in prey distributions and availability across the
landscape. This study provides novel insights into the trophic
generalism and adaptability of otters across Britain, which is likely to
have aided their recent population recovery, and may increase their
resilience to future environmental changes.