Using seabirds to map the distribution of elusive pelagic cephalopod species

Abstract

The distribution of oceanic cephalopod species is not fully understood but seabirds, who feed on cephalopods and cover vast oceanic areas, might work as samplers and mappers of the occurence of this elusive group. We tracked seventeen wandering albatrosses Diomedea exulans in Bird Island, South Georgia (54°S; 38°W) over the austral winter (breeding period) with GPS-loggers, activity recorders and stomach temperature probes. At logger retrieval, diet composition was accessed via stomach flushings of the tagged individuals. Wandering albatrosses captured circumpolar and rarer oceanic squid in all water masses of the Southern Ocean (i.e. Antarctic, sub-Antarctic and subtropical waters), complementing much of the knowledge about the cephalopod distribution in the Atlantic sector of the Southern Ocean. Some cephalopod species showed a wider distribution range, suggesting that despite of the oceanic fronts represent ecological barriers that limit their distribution, they are capable of overcoming these frontal regimes and even taking advantage of their waters as migration pathways.

The devil is in the detail: small-scale sexual segregation despite large-scale spatial overlap in the wandering albatross

“…However, by integrating GPS, immersion, STP and diet data from the tracked birds with remotely-sensed information on the environment, we show that within core foraging areas, male and female wandering albatrosses differed in the conditions associated with ARS behaviour, location of feeding events, and prey species, thus providing evidence for sex-specific habitat segregation at local scale. Despite the recent progress in bio-logging technologies, there are still important gaps in our knowledge of how marine predators interact with the environment and their use of resources (Catry et al 2004;Pereira et al 2017). By combining data from multiple devices and conventional analysis of stomach contents, we were able to critically assess the foraging strategies of wandering albatrosses with a particularly high level of detail (Wilson et al 1995;Weimerskirch et al 1997b;Catry et al 2004;Weimerskirch et al 2007).…”

“…Histioteuthis atlantica, Taonius sp. B (Voss) and Galiteuthis glacialis, present in the diet of both sexes, were likely captured during long foraging excursions to sub-Antarctic and subtropical waters (Xavier et al 1999;Xavier et al 2016;Pereira et al 2017).…”

“…By combining these approaches with analyses of diet composition (from stomach contents), it is possible to determine not only where and when the prey was captured, but also the species and size, providing further insights into prey biogeography (Pereira et al 2017).…”

Changing measurements or changing movements? Sampling scale and movement model identifiability across generations of biologging technology

“…These data represent invaluable archives for reconstructing historical movement patterns of animals for comparison with more recent observations. They provide a window into the past for understanding animal movements and the influence of changing environmental conditions, including the abundance and distribution of prey (Pereira, Paiva, & Xavier, 2017;Seco et al, 2016). As animal movement databases grow (Birdlife International, 2004;Kranstauber et al, 2011), so do the opportunities for historical comparisons.…”

A novel metabarcoding primer pair for environmental DNA analysis of Cephalopoda (Mollusca) targeting the nuclear 18S rRNA region

“…Video surveys with submersibles and towed cameras require lights that are easily detectable by the welldeveloped cephalopod eyes, which may result in avoidance behaviour [3]. The study of cephalopod remains in the stomachs of predators provides indirect evidence of their presence [11][12][13], but the digested state of cephalopod remains may hamper species identification, and the selectivity of the predators and limited knowledge of their foraging area introduces bias. The challenges associated with cephalopod sampling, particularly in remote areas such as deep pelagic environments, raise an urgent need for novel monitoring methods.…”