Population Connectivity and Genetic Assessment of Exploited and Natural Populations of Pearl Oysters within a French Polynesian Atoll Lagoon

Abstract

In French Polynesia, the production and exportation of black pearls through the aquaculture of the black-lip pearl oyster Pinctada margaritifera provide the second largest economic income for the country after tourism. This industry entirely relies on the collection of natural spats from few highly recruiting lagoons. In recent years, pearl oyster producers have experienced variable success rates in spat collection, with significant spatial and temporal variability in spat supply, driving uncertainty in the future of pearl production. This study combines, for the first time in a farmed lagoon, genetic (SNPs), demographic (sex ratio, age), and biophysical data (larval dispersal modelling) to shed new light on population dynamics, connectivity, and spat recruitment in Ahe Atoll, a well-studied pearl farming site. Our results indicate that the geographical structuring of the natural populations and the contribution of both natural and exploited stocks to the production of spats result from the interaction of hydrodynamic features, life history traits and demographic parameters: the northeastern natural populations are older, not well connected to the southwestern natural populations and are not replenished by larvae produced by adjacent exploited populations. Moreover, we observe that the exploited populations did not contribute to larval production during our experiment, despite a sampling period set during the most productive season for spat collection. This is likely the result of a strong male bias in the exploited populations, coupled with a sweepstakes reproductive strategy of the species. Our results warrant further investigations over the future of the northeastern older natural populations and a reflection on the current perliculture techniques.

Environmentally Driven Color Variation in the Pearl Oyster Pinctada margaritifera var. cumingii (Linnaeus, 1758) Is Associated With Differential Methylation of CpGs in Pigment- and Biomineralization-Related Genes

“…Additionally, the transgenerational effect described for maize, although not yet tested for pearl oysters, suggests that epigenetic marker-assisted selection could be envisioned. Such an approach may offer the possibility of selecting phenotypes of interest without the associated risk of eroding genetic diversity and/or the integration into natural populations of spat produced by farmed oysters ( Reisser et al, 2020 ).…”

“…Reads were cleaned and adaptors removed with Trimmomatic ( Bolger et al, 2014 ) (V. 0.36 – illuminaclip 2:30:10; leading 28, trailing 28, and minlen 40). Bismark aligner ( Krueger and Andrews, 2011 ) (V. 0.19) was used to map reads on the draft genome of P. margaritifera ( Reisser et al, 2020 ) using the following parameters: multi-seed length of 30 bp, 0 mismatches, default minimum alignment score function. Deduplication was done with Deduplicate_bismark ( Krueger and Andrews, 2011 ).…”

An appraisal of systematic conservation planning for Pacific Ocean Tropical Islands coastal environments

“…For instance, given the extent of black pearl farming activities in many French Polynesian lagoons, it is likely that specific SCP scenarios for optimal zoning according to this activity will emerge soon. These could also take advantage of hydrodynamic 3D models implemented to compute connectivity matrices for pearl oyster larval dispersal (Dumas et al, 2012;Thomas et al, 2016), as well as genetics study that can help mapping populations and larval dispersal source and sinks (Reisser et al, 2020). In the context of different uses and zones that require ad hoc management, such as mariculture, fishing and conservation zones specific SCP tools can help, such as Marxan with Zones.…”

“…Fourth, molecular data are increasingly available for POTIs and have long served conservation (Von der , but methods to include genetics and genomics data in SCP have only been emerging recently (Beger et al, 2014) and, to our knowledge, no example is available for the POTIs, yet. Molecular data are necessary to understand connectivity at population and evolutionary time scales and validate connectivity models (Treml et al, 2015, Reisser et al 2020, which could improve SCP to a great extent, depending on the scale of the exercise. However, considering the cost of sampling and analysis especially for population genetics, investigations can only be performed for a limited number of species, and the choice of candidate species is not trivial if the conservation objective is general and not specific to those species.…”

Correction: Reisser, C.M.O. et al. Population Connectivity and Genetic Assessment of Exploited and Natural Populations of Pearl Oysters within a French Polynesian Atoll Lagoon. Genes 2020, 11, 426

“…The authors wish to make the following corrections to this paper [1], regarding an error in Figure 6.…”