History has been made during a research expedition currently underway involving a rich representation of young researchers. This cruise is a prologue to the ongoing, collective effort of a number of institutions across the country that seek to develop the capacity of marine researchers, both established and emerging, to better serve the common goals of safeguarding and improving the social and natural systems of South Africa’s oceans. One Ocean Hub (OOH) is the sole funder of this expedition and the cruise contributes to their core Capacity Strengthening objective for deep-sea research and management in South Africa.
Deep diversity
The primary intention of this voyage is to harness the potential of young, local scientists, and in the process, foster and strengthen connections that transverse the boundaries of disciplines, which have historically operated in isolation. The aim of this is to then facilitate a greater understanding of South Africa’s oceans, and to approach the management thereof more holistically and more representatively, to foster strengthened stewardship. Along their journey, the team witnessed a pioneering voyage to the depths of our ocean canyons, with the advent of a new technology in South African waters.
Deep beginnings
The use of remotely operated vehicles (ROV) has proven to be a vital medium for surveying deep-sea habitats previously concealed by their inaccessibility. In addition to the twenty successful ROV dives carried out on this expedition, new technology has been employed as a means to observe life at great depths for extended periods. Baited landers are cameras mounted on a weighted frame that land on the sea floor. The model in use has two cameras positioned to film a lit-up canister filled with bait, used to observe and measure rarely seen deep-sea creatures that are attracted by the scent of the bait. The twin cameras provide images in stereo, allowing for accurate size measurements, which are important in fishery science.
Unlike the ROV, which can only operate to 300 meters, the landers are untethered (with no umbilical connecting them to the vessel), so they can be deployed to depths as great as 1000 meters, and beyond. A further key difference is that ROVs are flown by trained pilots, whereas landers are unmanned and can be left on the sea floor while other work is underway making them great for multidisciplinary surveys. The team has been surveying at three depths; 300, 600, and 900 meters in order to compare life in different depth zones. When the team is ready to retrieve them, they use acoustic release technology to do so. It takes several minutes for the precious equipment to traverse the great distance from the sea floor, and they have to scan the rolling blue swell with great care so that they might see the yellow structure resurface.
The first deployment to 300 meters yielded a fish of impressive size, known as a hapuku wreckfish. Some of the other interesting characters that arrived included bright red rockfish (jacopevers), spindly, long-legged stone crabs, grenadiers with rippling tails and enormous eyes, and cutthroat eels sporting prehistoric jaws and serpentine bodies. Numerous species of deep-water sharks were observed including the arrowhead dogfish and balloon catsharks, both of which are near-threatened. To the collective delight of the team, a dumbo octopus was captured swimming by using its ear-like fins positioned on its head. This was the highlight of the deepest deployment at a depth of 1035 meters.
Deep insight
Development of the landers has been driven by Dr. Anthony Bernard, Instrument Scientist from SAIAB in an effort to expand visual census research that is common on the continental shelf into the deep sea.
The significance of this technology was explained by Dr. Bernard;
“Deep-sea landers are opening new avenues for offshore research and are providing the first images of slope ecosystems. This passive, non-invasive method of surveying will help to better inform the management of deep-sea and benthic habitats.”
This technology brings us to the forefront of contemporary deep-sea research and allows us to surpass the interface between known and unknown habitats. This will allow us to collect information about our slope habitats where activities like petroleum exploration and mining may occur. Data from the landers will feed into the national map of marine ecosystem types, which is a foundation for managing the use of ocean space. This serves a meaningful role in provisioning ocean services, allowing us to classify and quantify life at these great depths. It also deepens our literacy in this realm, as the quietness of the lander allows us to play the unobtrusive witness to the undisturbed behaviour of creatures that have long since been a mystery to us.
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