Slater, Matthew J., and Carton, Alexander G. (2010) Sea cucumber habitat differentiation and site retention as determined by intraspecific stable isotope variation. Aquaculture Research, 41 (10). pp. 695-702.

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Abstract

Stable carbon and nitrogen isotope ratios (δ13C/δ15N) were assessed as a means to ascertain the recent in situ feeding history of the common New Zealand sea cucumber Australostichopus mollis, in relation to nutrient enrichment from a longline green-lipped mussel (Perna canaliculus) farm in Northern New Zealand. δ13C and δ15N isotopic signatures and ratios of sea cucumbers sampled from within the impact footprint of the mussel farm were compared to those of sea cucumbers residing on adjacent natural reefs. Sea cucumbers from beneath mussel farming longlines had significantly different δ13C stable isotope signatures in comparison to sea cucumbers collected from neigbouring natural reef habitats. This difference supports the hypothesis that sea cucumbers in the same bay maintain distinctly different feeding histories, with those residing beneath mussel farming longlines deriving tissue carbon from sediment impacted by farming activities. This hypothesis is further supported by the finding that the isotope signature of sediment collected from beneath the mussel farm is consistent with the expectation that sea cucumbers were feeding on and consuming sediment enriched with bivalve waste (faeces and pseudo-faeces). In contrast the nitrogen stable isotope signature (δ15N) was found to be similar between sites, for both sea cucumbers and assumed food sources. Both findings lend support to the viability of future sea cucumber/green-lipped mussel farm polyculture systems. Sea cucumbers in different locations (mussel farm, natural reef) possessed distinctly different isotope signatures suggesting that mixing of sea ranched sea cucumbers with natural reef populations would be negligible or non-existent. Similarities between the isotope signatures in low metabolic tissue of sea cucumbers residing at the mussel farm site to that of mussel farm impacted sediment suggests that cucumbers beneath mussel farms appear to have high rates of retention at the farm site.

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