Trophic Ecology of the Marine Otter (Lontra felina): Review, Quantitative Analyses and Population Implications

The marine otter, Lontra felina, is one of the top predators of the benthic communities in the southeastern Pacific coasts, from Chimbote in Peru to Cape Horn in Chile. Despite its importance in these coastal food webs, few studies exist to date on its trophic ecology and an up-to-date comprehensive understanding is needed. A systematic review was thus done on the trophic ecology of L. felina, gathering data to address diet composition, feeding patterns and the role of diet on population variability throughout its distribution. The diet of the marine otter comprises a broad spectrum of prey items, including fish, crustaceans, mollusks, birds, echinoderms, mammals, insects, tunicates and even fruits, supporting its classification as a dietary generalist and opportunist. Quantitative analyses on dietary variation across its range revealed a feeding-related biogeographical pattern, consisting of a latitudinal gradient with a higher consumption of fish to the north and crustaceans to the south. Moreover, the feeding ecomorphology of L. felina shows that this variation in diet is linked to the phenotypic characteristics of the populations. Northern marine otters, with a higher consumption of fish, exhibit a piscivory-associated morphology (narrower skulls and longer rostrums), while southern marine otters, with a higher consumption of crustaceans, present a durophagy-associated morphology (wider skulls and shorter rostrums). Considering the genetic differences between both populations and the trophic and morphological variations described, it is possible to suggest the existence of a divergence scenario between northern and southern populations of the marine otter, whose knowledge is highly relevant for its conservation given its current status as an endangered species. Despite this, the lack of information on different topics is highlighted, which traces the long road ahead in the study of the trophic ecology of L. felina.