DEA research team returns with the first visuals of the Cape Canyon seabed
29 March 2018
A team of Department of Environmental Affairs’ (DEA) researchers (scientists and technicians) have returned from a four-week research expedition, on board the R/V Algoa. The cruise covered an area of over 100 x 300 km2 where information on the biodiversity, oceanography and geology was collected throughout the operational area.
Amongst other successes, the team returns with the first visuals of the rocky habitats of Cape Canyon seafloor, and in doing so advance the knowledge of deep-sea research in the country. The overarching aim of this expedition was to document and explore some of the uncharted areas of largest known submarine canyon off the South African west coast- the Cape Canyon.
South Africa not only boasts a spectacular number of canyons on land but also has a notable amount of underwater canyons, such as the Cape Canyon, which may be foreign to the human eye. Such underwater features are reported to potentially play a significant ecological role in the life history of some commercial resources (e.g. hake), and their unique structure connects the coastline to the deep-sea environment. Apart from their ecological functions, intensified upwelling events have been noted within submarine canyons and these in turn may power cetacean and seabird feeding grounds.
In light of the canyon’s countless potential ecological services, the Department of Environmental Affairs: Oceans and Coast Branch initiated a 3 year collaborative project; in order to provide insights on the functionality of the Cape Canyon in relation to nearshore and offshore areas. The survey design undertaken followed an array of ship-based sampling methods, which included a tow-camera system that takes images and videos of the seabed; a bottom sampler collecting sediment from the seafloor; a dredge which collects invertebrate animal samples from above the seabed; and a Conductivity Temperature Depth (CTD) device package that records information on the conductivity, temperature, salinity, and collects water samples to analyse environmental variables at different depths throughout the water column.
Apart from these physical sampling approaches, an acoustic device which releases sound at different rates produced a map outlining the topography of the canyon. Cetacean and seabird observers also participated and provided information on the distribution and abundance of the different species recorded within the canyon.
These 2016 - 2018 datasets will collectively provide answers to the project’s objective in characterising the area, and further complement South Africa’s Marine Spatial Planning efforts.
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