(1 - 2 of 2)
- First quantification of subtidal community structure at Tristan da Cunha Islands in the remote South Atlantic from kelp forests to the deep sea
- Tristan da Cunha Islands, an archipelago of four rocky volcanic islands situated in the South Atlantic Ocean and part of the United Kingdom Overseas Territories (UKOTs), present a rare example of a relatively unimpacted temperate marine ecosystem. We conducted the first quantitative surveys of nearshore kelp forests, offshore pelagic waters and deep sea habitats. Kelp forests had very low biodiversity and species richness, but high biomass and abundance of those species present. Spatial variation in assemblage structure for both nearshore fish and invertebrates/algae was greatest between the three northern islands and the southern island of Gough, where sea temperatures were on average 3-4o colder. Despite a lobster fishery that provides the bulk of the income to the Tristan islands, lobster abundance and biomass are comparable to or greater than many Marine Protected Areas in other parts of the world. Pelagic camera surveys documented a rich biodiversity offshore, including large numbers of juvenile blue sharks, Prionace glauca. Species richness and abundance in the deep sea is positively related to hard rocky substrate and biogenic habitats such as sea pens, crinoids, whip corals, and gorgonians were present at 40% of the deep camera deployments. We observed distinct differences in the deep fish community above and below ~750 m depth. Concurrent oceanographic sampling showed a discontinuity in temperature and salinity at this depth. While currently healthy, Tristan's marine ecosystem is not without potential threats: shipping traffic leading to wrecks and species introductions, pressure to increase fishing effort beyond sustainable levels and the impacts of climate change all could potentially increase in the coming years. The United Kingdom has committed to protection of marine environments across the UKOTs, including Tristan da Cunha and these results can be used to inform future management decisions as well as provide a baseline against which future monitoring can be based.
- Caselle, Hamilton, Davis, Thompson, Turchik, Jenkinson, Simpson, Sala
- Ecosystem assessment of the Tristan Da Cunha Islands
- In January–February 2017, National Geographic’s Pristine Seas project, in collaboration with the Royal Society for the Protection of Birds (RSPB) and the Tristan da Cunha Government (including the Fisheries and Conservation Departments) conducted a 21-day expedition to Tristan da Cunha, Nightingale, Inaccessible and Gough Islands. The primary goals of the expedition were to conduct comprehensive quantitative surveys of the health of the archipelago’s largely unknown marine environment to assist the Government and people of Tristan da Cunha in planning marine protection . The results of the expedition highlight the unique marine ecosystem of this archipelago, particularly the pelagic and deep-sea environments, which were virtually unstudied and documented scientifically.The work presented in this report is meant to complement ongoing research at Tristan da Cunha and provide a springboard to help inform the Tristan Government about potential protection schemes that protect both important fisheries and unique biodiversity of the archipelago. .
- Caselle, Hamilton, Davis, Bester, Wege, Thompson, Turchik, Jenkinson, Simpson, Mayorga