SA Number: 1.2
Name of the SA: Fram – Fram Strait, Arctic: time series on megafauna density and diversity
Institute: Alfred Wegener Institut
Higher life at the Arctic deep seafloor: results of long-term image analyses from a towed camera system.
Ecosystems deeper than 2000 m cover ~60% of the Earth’s surface and represent the world’s most vast biome. Because of technological and time constraints, <1% of this has been studied. Still less is known about deep-sea ecosystems in remote Polar Regions, as they are less accessible due to ice cover and harsh environmental conditions for most of the year. This service activity focuses on the megabenthic composition of a polar, soft-sediment ecosystem at the HAUSGARTEN observatory.
The seafloor of selected stations of the HAUSGARTEN observatory is surveyed regularly by a towed Ocean Floor Observation System (OFOS; Fig. 1). The vertically facing camera system is used to assess large-scale distribution patterns of larger epi-benthic organisms and other objects (e.g. dropstones, garbage) at the deep seafloor (Fig. 2). The system is lowered to approx. 1.5 m above ground using a fibre optical cable for data, video and energy transfer, and then towed along a transect at a speed of 0.5 knots. The OFOS newly designed by the Deep-sea Research Group at AWI consists out of a metal frame equipped with a Canon camera (EOS-1Ds Mark III, modified for underwater applications by iSiTEC GmbH, Germany), a strobe (Kongsberg 0E11-242), four LED lights (LED Multi-Sealite, DeepSea Power & Light), telemetry (LRT-400 Fiber, iSiTEC), and three red laser points (OKTOPUS), positioned 50 cm apart from each other. The still camera is triggered automatically every 30 sec to minimise spatial overlap of images. Additional manually triggered images can be taken when features of particular interest occurred in the viewfinder.
OFOS images are stored in the PANGAEA repository and analysed on the web interface BIIGLE by experts worldwide. The global access enables quality control of analysed images and enhances scientific exchange between experts for different taxonomic groups. A newly developed GIS based web-viewer (Fig. 3) gives also interested amateurs the opportunity to get closer insight to locations of images taken and associated results of organism abundances from the image analysis.
Long-term time series of seafloor community data are provided via PANGAEA that can be used to assess the impact of ocean changes. The data give the users the extremely rare opportunity to study benthic communities at the Arctic deep seafloor over longer time scales. The data can also be used to calculate benthic biomass and production, as well as base line to assess the impact of global warming and concomitant anthropogenic threats to the Arctic ecosystem such as fisheries, litter contamination, tourism and shipping.
|SA1.2 Figure 1||5.6 MiB|
|SA1.2 Figure 2||745.5 KiB|
|SA1.2 Figure 3||227.0 KiB|