The University of Aberdeen’s Oceanlab has constructed a fleet of landers to investigate the deep-sea with the intention of expanding our understanding of its inhabitants and their role within our oceans.
Robust Biodiversity lander (ROBIO)
By Nicola King, Alan Jamieson, Kirsty Kemp, Phil Bagley and Monty Priede
The deep-sea represents the largest habitat on Earth with 79% of the volume occupied by life inhabiting depths exceeding 1000m. Animals that live in the deep-sea are adapted to extreme conditions, including high pressure, little or no light, low temperatures and reduced food supply. The deep-sea environment and the organisms therein are therefore extremely difficult for scientists to observe and study.
The deep-sea community is supported by the import of particulate organic matter (POM) derived from surface primary production. A proportion of the surface primary production reaches the seafloor in the form of animal carcasses. Scavenging animals such as crustaceans and fish utilise such food-falls and are thought to be attracted to the carcasses by odour plumes spreading across the seafloor.
One of the present challenges in deep-sea research is to understand how agents, such as fish, transport this organic matter across the sea floor. In this respect the study of deep-sea animals is essential to the understanding of carbon cycling and dispersal in the world’s oceans. Another future area of research will be to determine the affects of current regime and complex topography on odour plumes using computer-modelling techniques. Advanced odour plume models will enable accurate species abundance estimates to be made.
One of the most successful and widely applicable methods for studying deep-sea fauna in situ is the autonomous lander vehicle. Autonomous landers have gained widespread acceptance as a tool for deep-sea research through the optimisation of ship-time and the ability to carry out studies without removing animals from their natural environment. Landers are also completely independent of the ship, unlike manned submersibles and remotely operated vehicles (ROVs), and can be left to work autonomously while the ship continues with other tasks.
A typical lander is comprised of a short positively buoyant mooring line, a metal frame on which to mount scientific instruments and releasable ballast weights. Landers are deployed from a ship whereupon they free-fall to the seabed. On touchdown, pre-programmed observation or monitoring tasks can operate for periods of hours to months. At the end of the experiment an acoustic command from the ship releases ballast weights and the vehicle ascends to the surface by virtue of positive buoyancy.
Deep Ocean Benthic Observer (DOBO)
Since the 1980’s, the Aberdeen University Deep Ocean Submersible (AUDOS) lander has provided time-lapse photographic biodiversity surveys in a variety of applications around the world. Following the success of AUDOS, the Robust Biodiversity lander (ROBIO) has been constructed to provide rapid biodiversity surveys down to 6000m. The ROBIO is a deep-sea photographic lander, with instrumentation allowing salinity, temperature and depth profiling, current measurement, and animal community observation. Amalgamation of this biological and physical data allows distribution maps of deep-sea habitats and species to be constructed. ROBIO is due to be deployed on the second leg of the MAR-ECO cruise on the Mid-Atlantic Ridge. The mission objective is to identify potential variations in the types of animals present at different locations on the ridge.
The Deep Ocean Benthic Observer (DOBO) lander is designed to investigate fish distribution and migration patterns in response to physical oceanographic conditions for up to 9-months at a time. It aims to identify and understand the significance of environmental time signals available to deep-sea organisms. The fish are photographed using a time-lapsed stills camera and physical data is obtained using a current profiler. he DOBO lander will use the novel long-term periodic bait release mechanism for the first time on the forthcoming MAR-ECO cruise. The experiment is designed to introduce bait into view of the camera every 5 days over a period of one month. This technique is the equivalent of regular baited camera experiments over extended periods, but with a greatly reduced need for ship time.
For further information about the University of Aberdeen’s Oceanlab and deep-ocean landers please visit our website at: www.abdn.ac.uk/oceanlab