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Habitat partitioning in Antarctic krill: Spawning hotspots and nursery areas

Habitat partitioning in Antarctic krill: Spawning hotspots and nursery areas
Habitat partitioning in Antarctic krill: Spawning hotspots and nursery areas
Antarctic krill, Euphausia superba, have a circumpolar distribution but are concentrated within the south-west Atlantic sector, where they support a unique food web and a commercial fishery. Within this sector, our first goal was to produce quantitative distribution maps of all six ontogenetic life stages of krill (eggs, nauplii plus metanauplii, calyptopes, furcilia, juveniles, and adults), based on a compilation of all available post 1970s data. Using these maps, we then examined firstly whether “hotspots” of egg production and early stage nursery
occurred, and secondly whether the available habitat was partitioned between the successive life stages during the austral summer and autumn, when krill densities can be high. To address these questions, we compiled larval krill density records and extracted data spanning 41 years (1976–2016) from the existing KRILLBASE-abundance and KRILLBASE-length-frequency databases. Although adult males and females of spawning age were widely distributed, the distribution of eggs, nauplii and metanauplii indicates that spawning is most intense over the shelf and shelf slope. This contrasts with the distributions
of calyptope and furcilia larvae, which were concentrated further offshore, mainly in the Southern Scotia Sea. Juveniles, however, were strongly concentrated over shelves along the Scotia Arc. Simple environmental analyses based on water depth and mean water temperature suggest that krill associate with different habitats over the course of their life cycle. From the early to late part of the austral season, juvenile distribution moves from ocean to shelf, opposite in direction to that for adults. Such habitat partitioning may reduce intraspecific competition for food, which has been suggested to occur when densities are exceptionally high during years of strong recruitment. It also prevents any potential cannibalism by adults on younger stages. Understanding the location of krill spawning and juvenile development in relation to potentially overlapping fishing activities is needed to protect the health of the south-west Atlantic sector ecosystem.
1932-6203
Perry, Frances A.
0981084f-aec1-4508-9b8f-4859b67b327a
Atkinson, Angus
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Sailley, Sevrine
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Tarling, Geraint
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Hill, Simeon L.
fa9232ef-672c-4c5d-aca2-98168d352a19
Lucas, Catherine
521743e3-b250-4c6b-b084-780af697d6bf
Mayor, Daniel J.
a2a9c29e-ffdc-4858-ad65-3a235824a4c9
Perry, Frances A.
0981084f-aec1-4508-9b8f-4859b67b327a
Atkinson, Angus
77d9c544-2749-46fe-b991-df2a11d1d6be
Sailley, Sevrine
afda91a1-33cc-4ae5-a9f1-159508aa1963
Tarling, Geraint
1dec90db-7db7-4563-a6a5-894931138e07
Hill, Simeon L.
fa9232ef-672c-4c5d-aca2-98168d352a19
Lucas, Catherine
521743e3-b250-4c6b-b084-780af697d6bf
Mayor, Daniel J.
a2a9c29e-ffdc-4858-ad65-3a235824a4c9

Perry, Frances A., Atkinson, Angus, Sailley, Sevrine, Tarling, Geraint, Hill, Simeon L., Lucas, Catherine and Mayor, Daniel J. (2019) Habitat partitioning in Antarctic krill: Spawning hotspots and nursery areas. PLoS ONE, 14 (7). (doi:10.1371/journal.pone.0219325).

Record type: Article

Abstract

Antarctic krill, Euphausia superba, have a circumpolar distribution but are concentrated within the south-west Atlantic sector, where they support a unique food web and a commercial fishery. Within this sector, our first goal was to produce quantitative distribution maps of all six ontogenetic life stages of krill (eggs, nauplii plus metanauplii, calyptopes, furcilia, juveniles, and adults), based on a compilation of all available post 1970s data. Using these maps, we then examined firstly whether “hotspots” of egg production and early stage nursery
occurred, and secondly whether the available habitat was partitioned between the successive life stages during the austral summer and autumn, when krill densities can be high. To address these questions, we compiled larval krill density records and extracted data spanning 41 years (1976–2016) from the existing KRILLBASE-abundance and KRILLBASE-length-frequency databases. Although adult males and females of spawning age were widely distributed, the distribution of eggs, nauplii and metanauplii indicates that spawning is most intense over the shelf and shelf slope. This contrasts with the distributions
of calyptope and furcilia larvae, which were concentrated further offshore, mainly in the Southern Scotia Sea. Juveniles, however, were strongly concentrated over shelves along the Scotia Arc. Simple environmental analyses based on water depth and mean water temperature suggest that krill associate with different habitats over the course of their life cycle. From the early to late part of the austral season, juvenile distribution moves from ocean to shelf, opposite in direction to that for adults. Such habitat partitioning may reduce intraspecific competition for food, which has been suggested to occur when densities are exceptionally high during years of strong recruitment. It also prevents any potential cannibalism by adults on younger stages. Understanding the location of krill spawning and juvenile development in relation to potentially overlapping fishing activities is needed to protect the health of the south-west Atlantic sector ecosystem.

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Accepted/In Press date: 20 June 2019
Published date: 24 July 2019

Identifiers

Local EPrints ID: 433611
URI: https://eprints.soton.ac.uk/id/eprint/433611
ISSN: 1932-6203
PURE UUID: a511d1e7-5828-4190-adae-ea27903d5ecf
ORCID for Frances A. Perry: ORCID iD orcid.org/0000-0003-1560-1506
ORCID for Catherine Lucas: ORCID iD orcid.org/0000-0002-5929-7481

Catalogue record

Date deposited: 28 Aug 2019 16:30
Last modified: 30 Nov 2019 01:44

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