Habitat and trophic ecology of Antarctic squid: Where do young and adults live and what do they eat?
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1
Universidade de Aveiro, Departamento de Biologia, Portugal
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2
Departamento das Ciências da Vida, Universidade de Coimbra, MARE - Marine and Environmental Sciences Centre, Portugal
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3
Centre d’Etudes Biologiques de Chizé, UMR 7372 du CNRS-Université de La Rochelle, France
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4
CESAM - Centre for Environmental and Marine Studies, Portugal
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5
National Institute of Water and Atmospheric Research Ltd., 301 Evans Bay Parade, Hataitai, New Zealand
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6
Albatross Research, 594 Rocks Road, New Zealand
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7
British Antarctic Survey, United Kingdom
Cephalopods play an important role in the Southern Ocean. As voracious predators and important prey of top predators, cephalopods connect the lower and the top levels of food chains. Despite their recognized importance on this ecosystem, very little is known about the distribution and the trophic ecology of cephalopods, in particular squid, from the Pacific Sector of the Southern Ocean.
Using wandering albatrosses (Diomedea antipodensis antipodensis and D. antipodensis gibsoni) that breed at the Antipodes and Auckland islands and forage in the Pacific sector of the Southern Ocean, as biological samplers, we applied stable isotopic analysis (δ13C and δ15N) to beaks of key Antarctic squid species consumed by these albatrosses. The beak grows throughout the squid life without being replaced, which allows us to study different life stages of the squid. Stable isotopes analyses of the beaks allow the determination of the latitudinal range (δ13C values is inversely proportional to latitude in Southern Ocean) and trophic relations (δ15N grows approximately 3‰ per trophic level) of squid species. We applied this technique for the first time in two regions of the lower beaks of 11 species of Antarctic squid, the tip of the rostrum and the wing, regions that refer to young and adult squid stages, respectively. This methodology allows to assess if Antarctic squid live their entire lives in Antarctic waters or if they cross various water masses further north (potentially being able to survive in a wider range of habitats).
Our results show that only 5 species are exclusive of a single water mass: Moroteuthis knipovitchi is present exclusively in Antarctic waters (south of the Antarctic Polar Front), and Taonius sp. (Clarke), Histioteuthis eltaninae, Gonatus antarcticus and Alluroteuthis antarcticus are present only in sub-Antarctic waters, between the Antarctic Polar Front (APF) and the Sub-Tropical Front (STF). Surprisingly, most of the species present isotopic signatures that indicate different water masses. For example, Kondakovia longimana migrate North across the APF from young to adult. However, most of the other studied species have isotopic signatures from the sub-Antarctic and sub-tropical (North of STF) regions, and show evidence of ontogenic migrations towards South. Octopoteuhis sp. and Cycloteuthis akimushkini, for example, share sub-Antarctic and sub-tropical waters during theirs adult and young stages, respectively.
All species tend to have higher content of δ15N in adult phase, although only four species, e.g. Alluroteuthis antarcticus and Galiteuthis glacialis, have significant differences between young and adult nitrogen signatures. Using a bayesian stable-isotope mixing models (SIAR) we determined the isotopic niche for every species and in only four there is an overlap between the young and the adult isotopic niche.
Our results show that most of the studied squid species have an ecological change between their young and adult life stage. This change can be on their habitat distribution, their trophic level, or both simultaneously.
Our work shows for the first time a temporal overview of the distribution and trophic patterns in the same individual. We show that most individuals increase their trophic level from young to adult and we reveal that most of the Antarctic squid species are able to cross oceanic fronts on a determined stage of their life cycle, something previously unexpected.
Keywords:
Cephalopoda,
distribution,
Ontogenic shift,
Stable isotopes,
Southern Ocean
Conference:
XIX Iberian Symposium on Marine Biology Studies, Porto, Portugal, 5 Sep - 9 Sep, 2016.
Presentation Type:
Oral Presentation
Topic:
1. ECOLOGY, BIODIVERSITY AND VULNERABLE ECOSYSTEMS
Citation:
Queirós
JP,
Cherel
Y,
Hilário
A,
Thompson
D,
Walker
K,
Elliott
G and
Xavier
JC
(2016). Habitat and trophic ecology of Antarctic squid: Where do young and adults live and what do they eat?.
Front. Mar. Sci.
Conference Abstract:
XIX Iberian Symposium on Marine Biology Studies.
doi: 10.3389/conf.FMARS.2016.05.00085
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Received:
21 May 2016;
Published Online:
02 Sep 2016.
*
Correspondence:
Mr. José P Queirós, Universidade de Aveiro, Departamento de Biologia, Aveiro, 3810-193, Portugal, jqueiros@student.uc.pt