Autonomous lander technology for biological research at mid-water, abyssal and hadal depths
Autonomous landers have gained widespread acceptance as an important tool for studying the deep-sea. The study of biology in the deep-sea has, in the past, been limited as changes in pressure and temperature often result in the mortality of target species. Although techniques such as trawling are an essential and informative method of research, the results often lack the necessary ecological, behaviour and long-term information required to understand the biological role in the deep-ocean ecosystem. The use of landers, however, allows non-invasive empirical investigations previously not possible to be performed in situ. Almost exclusively, current capabilities in the exploration and scientific study of the deep ocean are limited to <6000m. Here, I describe the techniques and technologies currently used to enhance and add further dimension to the quality of scientific research at mid-water (e.g. 1000-4000m), abyssal (2000-6000m) and hadal depths (6000-11,000m) using autonomous lander vehicles. Methods in short and long-term lander techniques (i.e. the ROBIO and DOBO landers) used to provide biodiversity surveys and long-term monitoring of mega faunal migration and distribution are described. The development of the first autonomous deep-sea fish respirometry experiment (i.e. the FRESP lander) is described, including incidental observations of benthopelagic fish behaviour in response to underwater structures. Extending the operational depths of modern lander systems from the abyssal zone to full ocean depths is described in the design of the Hadal-CAM. Similarly, a novel approach to obtaining ecological data in mid-water, an advanced vertical profiler using a variable buoyancy device (VBD), is proposed. The VBD also allows both the periodic landing of a vehicle without retrieval, and can minimise the disturbance to the sediment surface on touchdown.