Biology subjects

Peignon, C.

Publications and source records attributed to Peignon, C..

3 recordsLinked to original sources

bioRxiv2025

Giant Clam Gardens: Cultural practices and ecological implications for population resilience in New Caledonia

Giant clams (Tridacninae) are a key component of coral reef ecosystems and a major economic, subsistence, and cultural resource for Pacific Island communities. In New Caledonia where stocks are declining but giant clams retain an emblematic status, coastal communities have developed a traditional practice referred to as "giant clam gardens," involving the translocation and aggregation of wild individuals onto shallow reef flats near villages. This study provides the first formal assessment of the prevalence, cultural significance, and potential ecological benefits of this practice. Surveys conducted in 11 coastal tribes documented over 40 clam aggregations primarily composed of Hippopus hippopus, which varied greatly in terms of age (1-40 years), area (1-1080 m2) and abundance (from a few individuals up to more than 2 700). Our findings suggest that the practice of "giant clam gardens" is now fairly widespread and primarily reflect a pragmatic approach aimed at optimizing resource access, rather than conserving the resource. Population surveys confirmed the presence of five giant clam species (H. hippopus, Tridacna maxima, T. squamosa, T. derasa and T. crocea), but failed to report significant recruitment in and around aggregations up to 1km downstream from the study area. This work revealed that while notions of protection and conservation were occasionally mentioned during interviews, they were not cited as primary motivations by communities. Nonetheless, clam gardens may contribute to broader population resilience by enhancing reproductive biomass and supporting larval dispersal across larger spatial scales. Given the declining state of natural stocks and the persistence of strong cultural ties to giant clam harvesting, this practice represents a pragmatic, culturally embedded approach that can provide valuable insights for strengthening the sustainability of this resource.

ecology↗

bioRxiv2024

Vinegar injections can be used safely to control outbreaks of crown-of-thorns starfish (Acanthaster solaris) during the peak spawning season

Concerns are mounting over the effects of COTS outbreaks, prompting the need for integrated management strategies. Although direct control methods are short-term and localized, they remain one of the few operational tools that can be easily implemented by local actors. Vinegar injections have recently emerged as highly effective method; however their impact on reproductive behavior remains untested. Here, we investigated the short-term spawning response of mature COTS to double injections of household vinegar. First, COTS abundances and reproductive status were monitored during a massive outbreak affecting New Caledonias reefs. In-situ and laboratory experiments were then conducted to determine whether injected COTS would eventually release their eggs and trigger synchronized spawning among mature individuals in close proximity. Our results indicated that injections had no significant effect on spawning behavior, even in densely populated aggregations (>4000 COTS.ha-1). In the field, starfish exhibited ripe gonads with high gamete content (up to 35% of body weight) three days after conspecifics were injected. In the laboratory, mature COTS kept with injected, decaying individuals in a confined volume did not expel their gametes after two days. This suggests that vinegar injections could be used at any time, even during peak spawning, without risking synchronized spawning in the affected areas.

ecology↗

bioRxiv2020

Seascape genomics reveals candidate molecular targets of heat stress adaptation in three coral species

Anomalous heat waves are causing a major decline of hard corals around the world and threatening the persistence of coral reefs. There are, however, reefs that had been exposed to recurrent thermal stress over the years and whose corals appeared tolerant against heat. One of the mechanisms that could explain this phenomenon is local adaptation, but the underlying molecular mechanisms are poorly known. In this work, we applied a seascape genomics approach to study heat stress adaptation in three coral species of New Caledonia (southwestern Pacific) and to uncover molecular actors potentially involved. We used remote sensing data to characterize the environmental trends across the reef system, and sampled corals living at the most contrasted sites. These samples underwent next generation sequencing to reveal single-nucleotide-polymorphisms (SNPs) of which frequencies associated with heat stress gradients. As these SNPs might underpin an adaptive role, we characterized the functional roles of the genes located in their genomic neighborhood. In each of the studied species, we found heat stress associated SNPs notably located in proximity of genes coding for well-established actors of the cellular responses against heat. Among these, we can mention proteins involved in DNA damage-repair, protein folding, oxidative stress homeostasis, inflammatory and apoptotic pathways. In some cases, the same putative molecular targets of heat stress adaptation recurred among species. Together, these results underscore the relevance and the power of the seascape genomics approach for the discovery of adaptive traits that could allow corals to persist across wider thermal ranges.

evolutionary biology↗