A framework for mapping local knowledge on ciguatera and artisanal fisheries to inform systematic conservation planning

Millions of people’s livelihoods rely on artisanal fisheries. However, in many regions fishers are increasingly facing ciguatera poisoning, a seafood-borne illness. The toxin, produced by benthic dinoflagellates, can spread through marine food webs and to humans by direct consumption. Ciguatera risk can play a major role in fisher’s activities but has never been considered in any marine spatial plans thus far. To fill this gap, we examined if integrating ciguatera in systematic conservation plans could affect these decisions. We developed through map-based interviews, a novel seven-step framework to collect and map local knowledge on ciguatera risk and fisheries activities with two innovations: (i) better mapping of fishing grounds by combining geomorphological habitat and fishing gear information, and (ii) integrating ciguatera risk directly into systematic spatial planning designs and scenarios conceived to maximize benthic habitat conservation while minimizing impacts to fishers. The approach is illustrated for Raivavae Island, in French Polynesia, Pacific Ocean. We found that integrating ciguatera significantly improved prioritization solutions with a 24–38% decrease of costs to fishers compared with scenarios based solely on fishery data. This framework was designed for scientists and managers to optimize the implementation of conservation plans and could be generalized to ciguatera-prone areas

Screening for Predictors of Chronic Ciguatera Poisoning: An Exploratory Analysis among Hospitalized Cases from French Polynesia

Ciguatera poisoning is a globally occurring seafood disease caused by the ingestion of marine products contaminated with dinoflagellate produced neurotoxins. Persistent forms of ciguatera, which prove to be highly debilitating, are poorly studied and represent a significant medical issue. The present study aims to better understand chronic ciguatera manifestations and identify potential predictive factors for their duration. Medical files of 49 patients were analyzed, and the post-hospitalization evolution of the disease assessed through a follow-up questionnaire. A rigorous logistic lasso regression model was applied to select significant predictors from a list of 37 patient characteristics potentially predictive of having chronic symptoms. Missing data were handled by complete case analysis, and a survival analysis was implemented. All models used standardized variables, and multiple comparisons in the survival analyses were handled by Bonferroni correction. Among all studied variables, five significant predictors of having symptoms lasting ≥3 months were identified: age, tobacco consumption, acute bradycardia, laboratory measures of urea, and neutrophils. This exploratory, hypothesis-generating study contributes to the development of ciguatera epidemiology by narrowing the list from 37 possible predictors to a list of five predictors that seem worth further investigation as candidate risk factors in more targeted studies of ciguatera symptom duratio

Spatial Solutions and Their Impacts When Reshuffling Coastal Management Priorities in Small Islands with Limited Diversification Opportunities

In small islands, the potential for new coastal activities and management options are often spatially limited. To reduce dependence on external factors and increase the resilience of populations to global changes and fluctuations in international markets, a recommended pathway is to diversify activities. We used a systematic prioritization tool with single and multiobjective zoning to explore the feasibility of scenarios at various levels of spatial diversification in the Gambier lagoon (French Polynesia), where black pearl culture is economically and spatially dominant. Local managers are committed to economic, livelihood, and environmental sustainability and agree that prioritizing both artisanal fisheries, which provide local food security, and ecosystem conservation should also be considered. Diversification options included the optimized reallocation of farming concessions and the identification of different types of conservation areas while taking into account traditional management areas. The scenarios were set to minimize surface areas and loss of access to existing fishing grounds. The solutions were compared between the scenarios with different cost metrics, allowing further discussions with stakeholders and managers. The Gambier case study shows that exploring diversification options in small islands using systematic prioritization tools can provide local managers with tailor-made plans adapted to island development question

Tetrodotoxin Poisoning in Mainland France and French Overseas Territories: A Review of Published and Unpublished Cases

Tetrodotoxin is one of the most potent neurotoxins in the aquatic world. This review of published and unpublished reports aims to describe the poisoning cases that have occurred in mainland France and overseas territories. Six articles were included, with 13 poisoning events, individuals or collective (number (n) = 53 patients). Moreover, 13 unpublished poisoning events from toxicovigilance networks were found (n = 17). All cases happened in overseas territories: French Guyana (n = 7), New Caledonia (n = 11), Reunion (n = 35) and French Polynesia (n = 17). The median age was 36 years. The most frequent signs were neurological (81.8%), digestive (54.5%) and general (52.3%). Three cases of dysgueusia and nine cases of urogenital discomfort were observed in French Polynesia. Twelve severe cases were reported, including seven deaths. Only three events (11.5%) were documented by a tetrodotoxin assay. Two families of fish accounted for 91.6% of the poisonings: 33.3% due to the Diodontidae family and 58.3% to the Tetraodontidae family. Although rare, information and collection campaigns on tetrodotoxin poisoning are, therefore, essential

Branched-Chain and Aromatic Amino Acids in Relation to Fat Mass and Fat-Free Mass Changes among Adolescents: A School-Based Intervention

Plasma levels of branched-chain amino acids (BCAA) and aromatic amino acids (AAA) are considered early metabolic markers of obesity and insulin resistance (IR). This study aimed to assess changes in plasma concentrations of BCAA/AAA and HOMA-IR2 (homeostasis model assessment of IR) after intervention-induced modifications in fat mass (FM) and fat-free mass (FFM) among French Polynesian adolescents. FM, FFM, plasma levels of BCAA and AAA, HOMA-IR2 were recorded at baseline and post intervention among 226 adolescents during a 5-month school-based intervention on diet and physical activity. Participants were divided into two subgroups according to their college attendance status which determined their intervention adherence: externs/half-residents (n = 157) and residents (n = 69). Four ordinal categories of body composition changes post-intervention were created for the analysis (FMgain/FFMlost < FMgain/FFMgain < FMlost/FFMlost < FMlost/FFMgain). After 5 months, changes in BCAA (p−trend < 0.001) and AAA (p−trend = 0.007) concentrations were positively associated with ordinal categories of body composition. HOMA-IR2 significantly decreased with FMlost (−0.40; 95% CI, −0.60 to −0.20) and increased with FMgain (0.23; 95% CI, 0.11 to 0.36). Our results suggest that FM loss is associated with a decrease in concentrations of obesity and IR metabolic markers which is more substantial when FM loss is accompanied with FFM gain

Deep-Water Fish Are Potential Vectors of Ciguatera Poisoning in the Gambier Islands, French Polynesia

Ciguatera poisoning (CP) cases linked to the consumption of deep-water fish occurred in 2003 in the Gambier Islands (French Polynesia). In 2004, on the request of two local fishermen, the presence of ciguatoxins (CTXs) was examined in part of their fish catches, i.e., 22 specimens representing five deep-water fish species. Using the radioactive receptor binding assay (rRBA) and mouse bioassay (MBA), significant CTX levels were detected in seven deep-water specimens in Lutjanidae, Serranidae, and Bramidae families. Following additional purification steps on the remaining liposoluble fractions for 13 of these samples (kept at −20 °C), these latter were reanalyzed in 2018 with improved protocols of the neuroblastoma cell-based assay (CBA-N2a) and liquid chromatography tandem mass spectrometry (LC–MS/MS). Using the CBA-N2a, the highest CTX-like content found in a specimen of Eumegistus illustris (Bramidae) was 2.94 ± 0.27 µg CTX1B eq. kg−1. Its toxin profile consisted of 52-epi-54-deoxyCTX1B, CTX1B, and 54-deoxyCTX1B, as assessed by LC–MS/MS. This is the first study demonstrating that deep-water fish are potential ciguatera vectors and highlighting the importance of a systematic monitoring of CTXs in all exploited fish species, especially in ciguatera hotspots, including deep-water fish, which constitute a significant portion of the commercial deep-sea fisheries in many Asian–Pacific countrie

Evidence for the Range Expansion of Ciguatera in French Polynesia: A Revisit of the 2009 Mass-Poisoning Outbreak in Rapa Island (Australes Archipelago)

Ciguatera poisoning (CP) results from the consumption of seafood contaminated with ciguatoxins (CTXs). This disease is highly prevalent in French Polynesia with several well-identified hotspots. Rapa Island, the southernmost inhabited island in the country, was reportedly free of CP until 2007. This study describes the integrated approach used to investigate the etiology of a fatal mass-poisoning outbreak that occurred in Rapa in 2009. Symptoms reported in patients were evocative of ciguatera. Several Gambierdiscus field samples collected from benthic assemblages tested positive by the receptor binding assay (RBA). Additionally, the toxicity screening of ≈250 fish by RBA indicated ≈78% of fish could contain CTXs. The presence of CTXs in fish was confirmed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The potential link between climate change and this range expansion of ciguatera to a subtropical locale of French Polynesia was also examined based on the analysis of temperature time-series data. Results are indicative of a global warming trend in Rapa area. A five-fold reduction in incidence rates was observed between 2009 and 2012, which was due in part to self-regulating behavior among individuals (avoidance of particular fish species and areas). Such observations underscore the prominent role played by community outreach in ciguatera risk managemen

Tectus niloticus (Tegulidae, Gastropod) as a Novel Vector of Ciguatera Poisoning: Detection of Pacific Ciguatoxins in Toxic Samples from Nuku Hiva Island (French Polynesia)

Ciguatera fish poisoning (CFP) is a foodborne disease caused by the consumption of seafood (fish and marine invertebrates) contaminated with ciguatoxins (CTXs) produced by dinoflagellates in the genus Gambierdiscus. The report of a CFP-like mass-poisoning outbreak following the consumption of Tectus niloticus (Tegulidae, Gastropod) from Anaho Bay on Nuku Hiva Island (Marquesas archipelago, French Polynesia) prompted field investigations to assess the presence of CTXs in T. niloticus. Samples were collected from Anaho Bay, 1, 6 and 28 months after this poisoning outbreak, as well as in Taiohae and Taipivai bays. Toxicity analysis using the neuroblastoma cell-based assay (CBA-N2a) detected the presence of CTXs only in Anaho Bay T. niloticus samples. This is consistent with qPCR results on window screen samples indicating the presence of Gambierdiscus communities dominated by the species G. polynesiensis in Anaho Bay. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses revealed that P-CTX-3B was the major congener, followed by P-CTX-3C, P-CTX-4A and P-CTX-4B in toxic samples. Between July 2014 and November 2016, toxin content in T. niloticus progressively decreased, but was consistently above the safety limit recommended for human consumption. This study confirms for the first time T. niloticus as a novel vector of CFP in French Polynesia

Ostreopsis lenticularis Y. Fukuyo (Dinophyceae, Gonyaulacales) from French Polynesia (South Pacific Ocean): A revisit of its morphology, molecular phylogeny and toxicity

To date, the genus Ostreopsis comprises eleven described species, of which seven are toxigenic and produce various compounds presenting a major threat to human and environmental health. The taxonomy of several of these species however remains controversial, as it was based mostly on morphological descriptions leading, in some cases, to ambiguous interpretations and even possible misidentifications. The species Ostreopsis lenticularis was first described by Y. Fukuyo from French Polynesia using light microscopy observations, but without genetic information associated. The present study aims at revisiting the morphology, molecular phylogeny and toxicity of O. lenticularis based on the analysis of 47 strains isolated from 4 distinct locales of French Polynesia, namely the Society, Australes, Marquesas and Gambier archipelagos. Observations in light, epifluorescence and field emission scanning electron microscopy of several of these strains analyzed revealed morphological features in perfect agreement with the original description of O. lenticularis. Cells were oval, not undulated, 60.5–94.4 μm in dorso-ventral length, 56.1–78.2 μm in width, and possessed a typical plate pattern with thecal plates showing two sizes of pores. Phylogenetic analyses inferred from the LSU rDNA and ITS–5.8S sequences revealed that the 47 strains correspond to a single genotype, clustering with a strong support with sequences previously ascribed to Ostreopsis sp. 5. Clonal cultures of O. lenticularis were also established and further tested for their toxicity using the neuroblastoma cell-based assay and LCMS/MS analyses. None of the 19 strains tested showed toxic activity on neuroblastoma cells, while LCMS/MS analyses performed on the strains from Tahiti Island (i.e. type locality) confirmed that palytoxin and related structural analogs were below the detection limit. These findings allow to clarify unambiguously the genetic identity of O. lenticularis while confirming previous results from the Western Pacific which indicate that this species shows no toxicity, thus stressing the need to reconsider its current classification within the group of toxic species