Assessment of Sediment Quality and Vulnerability of Tropical Marine Species in the Society Islands, French Polynesia

Aquatic sediments act as reservoirs of multiple sources of pollutants, and the increasing urbanization of coastal marine areas generally contributes to the accumulation of contaminants, endangering aquatic life and biodiversity. In the present study, we assessed the toxicity of sediment sampled at 150 sites around six islands in the Society Archipelago, French Polynesia. This evaluation is based on the use of standardized biological assays, during larval development of tropical benthic species systems in sediment elutriates. The results have shown a significant correlation in the responses of the four species studied: the oyster Saccostrea cucculata, the sea cucumber Holothuria fuscogilva, the sea urchin Tripneustes gratilla, and the shrimp Litopenaeus stylirostris. Larvae of Holothuria fuscogilva and Tripneustes gratilla were the most sensitive and suitable for assessing sediment quality. Data mapping revealed high toxicity, up to 100% mortality of larvae, in selected sites such as the Vaitepiha river mouth, Titaaviri, Atimaono in Tahiti Islans, as well as ‘Ōpūnohu Bay, Cook Bay, and Haapiti Bay in Moorea, and lake Maeva in Huahine. This toxicity is attributable to various sources of pollution, including agricultural, urban runoff and industrial effluents, as well as harbor and leisure activities. This study provides a significant contribution by identifying species that will provide essential predictive tools for adaptive management of tropical lagoons and identifying areas that showed high rates of developmental anomalies, requiring increased monitoring.