A baseline assessment of deep-sea biodiversity, and guide for future actions to inform stewardship, in Trinidad and Tobago

The deep sea, covering nearly 70% of Trinidad and Tobago’s Exclusive Economic Zone (EEZ), is the least explored and understood ecosystem in the country. As deepwater oil and gas extraction accelerates, the need for robust biological baseline data has become paramount for informed decision-making. Due to limited capacities and the EEZ’s vast expanse, with depths ranging from 200 to 3500 m, biological knowledge of these habitats remains extremely limited, with few research cruises conducted to date. The state of knowledge of deep-sea biodiversity in Trinidad and Tobago was assessed by examining existing deep-sea biological records from peer-reviewed scientific literature, grey literature, museum databases and collections, and biodiversity databases. A total of 451 metazoan morphospecies belonging to 218 families have been reported in Trinidad and Tobago’s deep sea. These 1342 unique biological records span ten phyla, with 315 morphospecies classified as benthic and 136 as pelagic. The deep ocean remains largely unknown, including below 2049 m (~ 20% of the EEZ by area) where no research has been undertaken. Species richness continues to increase with sampling effort suggesting a high potential for undiscovered biodiversity. Collected over 57 years by eleven vessels or expeditions, with none originating from the Caribbean, we estimate that less than 9% of deep-sea biological samples have remained in-country. Overall, these findings underscore the urgent need for expanded systematic deep-sea research and data collection, and increased capacity sharing and technology transfer, to inform future ocean stewardship in Trinidad and Tobago.