Conservation decisions are based on biodiversity information: the number of species that live in an area, their abundances and distributions, and the threats that might cause their decline or extinction. Therefore, it is challenging to make informed conservation decisions if biodiversity information is limited. In the deep ocean, biodiversity data are very sparse.
Most of the ocean floor consists of habitats greater than 200 meters, where many species live yet biodiversity data are severely lacking. Some coral groups, like black corals, are thought to increase in diversity and abundance with increasing depth. With logistical challenges in observing and sampling in the deep, it is no surprise that very little is known about these habitats. This is also true for the relatively well-studied Great Barrier Reef and Coral Sea, where only two major deep-sea surveys have previously sampled biodiversity.
The first major expedition of the Coral Sea occurred in the late 1990s, conducted by the Queensland Museum. This expedition led to the discovery of previously unknown species and range expansions of known species. The second expedition in 2019 was conducted with CSIRO on-board RV Investigator (see blog post about this expedition, here).
These first two expeditions dredged the seafloor to discover what corals live in these deep habitats. However, specimens collected via dredges can be misleading. Luck of the draw, we don’t know what we are going to get when the dredge is dropped, dragged, and unloaded on the vessel deck. Also, the dredge type and the type of coral in its path can dictate what is and isn’t collected because certain corals can be brittle or highly flexible, preventing certain corals from being collected. Therefore, corals that are collected via dredging can’t represent total biodiversity.
From May to June 2020, Schmidt Ocean Institute’s R/V Falkor explored the Queensland Plateau to facilitate the Visioning the Coral Sea Marine Park expedition. On-board R/V Falkor is the Remotely Operated Vehicle (ROV) SuBastian, which is a large (size of a Volkswagen Beetle car) tethered robot that can reach 4,500 meters depth. With 4k video being relayed to the ship in real-time, for the first time we were able to see these habitats with our own eyes, and carefully collect corals and sponges with SuBastian’s robotic arms. Additionally, these videos and discoveries are being shared for the world to see (e.g., Seamounts, Canyons & Reefs of the Coral Sea – Voyage of Discovery).
A month of surveying the Queensland Plateau and collecting just over 100 corals and sponges, we now know what species are common in these habitats. In addition to creating a species checklist, we also collected specimens that are likely new to science, including black corals and carnivorous sponges. The next step is to closely examine the specimens to confirm our suspicions of new-to-science species, identify them to the species level, update our understanding of their geographic and bathymetric ranges, and sequence their DNA to understand their evolutionary histories. All this information will be given to decision-makers to maximize the effectiveness of their conservation strategies in the Great Barrier Reef and Coral Sea.
