Assessment of an alternative Pinctada margaritifera spat collector in French Polynesia

Type Article
Date 2021-07
Language English
Author(s) Crusot Margaux1, Lo C.2, Gaertner-Mazouni N.ORCID1
Affiliation(s) 1 : Univ. Polynesie Francaise, IFREMER, ILM, IRD, EIO UMR 241, Tahiti, French Polynesia
2 : CIV, Direction des Ressources Marines, Tahiti, French Polynesia
3 : Univ. Polynesie Francaise, IFREMER, ILM, IRD, EIO UMR 241, Tahiti, French Polynesia
Source Aquaculture Reports (2352-5134) (Elsevier BV), 2021-07 , Vol. 20 , P. 100751 (8p.)
DOI 10.1016/j.aqrep.2021.100751
Keyword(s) Pearl-farming, Pinctada margaritifera, Pinctada maculate, Spat collectors
Abstract

Plastic waste in the oceans is a growing concern due to its size diversity, its ubiquitous nature and its impact on both marine organisms and ecosystems. While threatened by this marine plastic litter, the aquaculture industries also represent one of its major sources. In French Polynesia, black-lip pearl oyster (Pinctada margaritifera) farming is no exception. Wild spat collection has been described as a source of pollution because of the numerous particularly fragile and brittle shade-mesh plastic collectors used locally and often mismanaged when no longer usable. Thus, with the aim of helping to reduce this pollution, the present study is focused on the assessment of reusable plate collector as a potential alternative. We tested, using an in situ approach, the influence of the collecting surface position (i.e. horizontal vs vertical), plate color (i.e. black vs orange) and density (i.e. 25 plates vs 50 plates) on Pinctada margaritifera and Pinctada maculata spat settlement. Our results showed that 50-plates collectors, whatever their color and position, were more efficient to collect both kinds of spat than shade-mesh collectors (P < 0.0001). They also induced a higher number of Pinctada margaritifera spat than on the 25-plates collection device although there was no significant difference in numbers of Pinctada maculata spat (P < 0.0001). However, every type of plate collector presented a decreased mean length of the spat collected (P < 0.0001) compared to the shade-mesh collector. Furthermore, horizontal positioning of the collecting surface greatly improved the spat numbers on plate collectors (P < 0.0001) although there was no effect on shade-mesh collectors (P > 0.05). Finally, our results indicated that, among all the devices tested, the black horizontal 50-plates collector was the most efficient to collect spat and particularly Pinctada margaritifera. These first findings thus tend to suggest that these black re-usable plate collectors could be an efficient alternative to the currently used shade-mesh collectors.

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