Trophic Niche Dynamics and Diet Partitioning of King Crab Lithodes santolla in Chile’s Sub-Antarctic Water

Claudia Andrade,Fernanda Ovando,Erik Daza,Cristóbal Rivera,Luis Miguel Pardo,Flavia Morello,Eduardo Almonacid

doi:10.3390/d14010056

Abstract

The southern king crab Lithodes santolla is one of the most economically important fishery species in the southern waters of the Atlantic and Pacific Oceans. A combination of stomach content and stable isotope analyses was used to reveal the potential dietary characteristics, isotopic niche, overlap among maturity stages and sexes, and trophic relationships of an L. santolla population in the Nassau Bay, Cape Horn region. Stable isotope analyses indicated that L. santolla assimilated energy from a basal carbon source, the giant kelp Macrocystis pyrifera, forming the trophic baseline of the benthic food web. Moreover, the trophic position of L. santolla varied among late juveniles and adults, suggesting that the southern king crab does undergo an ontogenetic diet shift. L. santolla exhibited intraspecific isotopic niche variation, reflecting niche differentiation which allows the species to partition resources. The trophic relationships of L. santolla with the associated fauna suggested some potential interactions for food resources/habitat use when they are limited. This study is the first attempt to characterize the trophic dynamics of the southern king crab in the Cape Horn area and, by generating more data, contributes to the conservation of the king crab population and the long-term management of local fisheries that rely on this resource.

Highlights

Large stocks of the southern king crab Lithodes santolla (Molina, 1782) (Decapoda, Lithodidae) are distributed along coastal waters and fjords in the sub-Antarctic Magellan and Cape Horn region, at the southern tip of South America
The information presented here could be considered for the establishment of the regular monitoring of isotopic composition in southern king crab populations, as measures of niche and trophic position reflect the state of the populations summarizing the changes in a species’ population dynamics [118]
Our study could be considered a benchmark for future surveys of Lithodes santolla within and among populations since the increase or decrease in trophic position and variation of trophic niche width could indicate changes in the availability of prey and the reduction of the adult fraction or an increase in juveniles of the population of L. santolla

Summary

Introduction

Large stocks of the southern king crab Lithodes santolla (Molina, 1782) (Decapoda, Lithodidae) are distributed along coastal waters and fjords in the sub-Antarctic Magellan and Cape Horn region, at the southern tip of South America. The species has very high economic value, depending on small-scale local artisanal fisheries that have, generated dynamic histories of overfishing and governmental management. It is considered a high-status seafood source and a gastronomic footprint for tourism [1]. The modern history of its exploitation shows a peak towards the beginning of the 21st century. In the 1950s, it was only subject to local consumption and rapidly started to acquire significant status within regional gastronomy during the following decade. Since the late 1970s, it has had a consistent exploitation and high valuation as an export product for elite consumption (Mateo Martinic, 2022, personal communcation)

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