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Population structure of the hadal amphipod Bathycallisoma (Scopelocheirus) schellenbergi in the Kermadec Trench and New Hebrides Trench, SW Pacific

Lookup NU author(s): Dr Thomas Linley, Dr Alan Jamieson

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This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).


Abstract

© 2017. Deep-sea animals inhabiting the hadal zone (>6000. m deep) are frequently reported to occupy large bathymetric ranges, but details of intra-specific population structure and the underlying drivers remain poorly understood. Here we describe the population structure of the dominant SW Pacific hadal amphipod, Bathycallisoma schellenbergi, across its bathymetric range in the Kermadec (10,047. m) and New Hebrides (7156. m) trenches and explore the factors likely responsible for the observed patterns. These two trenches are relatively close geographically but underlie different water masses and are topographically isolated by the Kermadec fore-arc. The minimum depth of B. schellenbergi was ~1000. m shallower in the New Hebrides Trench than in the Kermadec Trench although similar patterns of ontogenetic stratification were present; juveniles were restricted to depths <~7000. m, larger adults were deeper toward the trench axes, regardless of absolute depth. We suggest that the increased juvenile presence around the abyssal-hadal transition zone is driven by reduced competition and a relaxation of pressure effects on metabolism. Evidence is also presented for morphological heterogeneity indicating geographic isolation between the two trenches. Interestingly, the absence of another major scavenging amphipod, Hirondellea dubia, at mid-trench depths corresponded to maximum densities of B. schellenbergi, a trend that was reversed towards the trench axes regardless of actual depth. This suggests that the population structure and amphipod assemblages are more affected by how trench topography influences the distribution of food and potential ecological interactions, rather than simply by the effects of hydrostatic pressure.


Publication metadata

Author(s): Lacey NC, Mayor DJ, Linley TD, Jamieson AJ

Publication type: Article

Publication status: Published

Journal: Deep-Sea Research Part II: Topical Studies in Oceanography

Year: 2018

Volume: 155

Pages: 50-60

Print publication date: 01/09/2018

Online publication date: 04/05/2017

Acceptance date: 02/04/2016

ISSN (print): 0967-0645

ISSN (electronic): 1879-0100

Publisher: Elsevier Ltd

URL: https://doi.org/10.1016/j.dsr2.2017.05.001

DOI: 10.1016/j.dsr2.2017.05.001


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