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Highly localised distribution patterns of juvenile sea cucumber Australostichopus mollis

journal contribution
posted on 2021-08-02, 01:06 authored by MJ Slater, Alexander CartonAlexander Carton, AG Jeffs
Information on the environmental characteristics of the juvenile habitat of many deposit-feeding sea cucumber species is limited, despite most fished species exhibiting rapid localised depletion. The current study combined large and small scale surveying techniques within a New Zealand harbour to identify areas with high densities of juvenile Australostichopus mollis, a commercially valuable aspidochirote holothurian. Data from detailed surveys were used to relate densities of juveniles and adults with measures of physical habitat characteristics including depth, sediment facies type, grain size range, as well as measures of chlorophyll-a, phaeopigment, carbon and nitrogen content of surface sediment. Results revealed a highly localised distribution of juvenile A. mollis focused on one site associated with an area of high adult density. Sites of high juvenile A. mollis density were characterised by sediment qualities favouring epibenthic detritivorous deposit feeding, including high nitrogen content, high phaeopigment:chlorophyll-a ratio and small grain size. The high-density juvenile site had facies that were further characterised by the presence of large shell fragments (>10 cm length) of the horse mussel (Atrina zelandica), which may provide a unique settlement microhabitat for early juveniles. Unlike some other sea cucumber species, juvenile A. mollis shows no distinct spatial separation from adult sea cucumbers, no association with dense macroalgae and no clear preference for shallower depths than adults. Overall, the results illustrate the highly localised pattern of recruitment of this species to a widely distributed adult population, which may help to explain the lack of previous observations of juveniles in this species. These results indicate the importance of identifying and protecting what appear to be very specific juvenile habitats in deposit-feeding sea cucumbers to ensure continuing recruitment to exploited populations.

Funding

Category 3 - Industry and Other Research Income

History

Volume

44

Issue

4

Start Page

201

End Page

216

Number of Pages

16

eISSN

1175-8805

ISSN

0028-8330

Publisher

Taylor & Francis

Language

en

Peer Reviewed

  • Yes

Open Access

  • No

External Author Affiliations

Newcastle University, UK; University of Auckland, NZ

Era Eligible

  • Yes

Journal

New Zealand Journal of Marine and Freshwater Research

Article Number

PII 931468978