Lookup NU author(s): Dr Thomas Linley,
Dr Alan Jamieson
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND).
© 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.
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
Print publication date: 01/09/2018
Online publication date: 04/05/2017
Acceptance date: 02/04/2016
Date deposited: 09/08/2017
ISSN (print): 0967-0645
ISSN (electronic): 1879-0100
Publisher: Elsevier Ltd
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