Kategorie: News
Scientists from the Thünen Institute of Sea Fisheries, Alfred Wegener Institute (AWI) and Helmholtz-Zentrum Geesthacht (HZG) have placed an optical-acoustic underwater observatory in the North Sea near Helgoland. It will be used to photograph and automatically identify the smallest marine life 24 hours a day and even under harsh conditions when research vessels are unable to leave the harbour.
Zooplankton are microscopic creatures, fish larvae, jellyfish as well as juveniles of many snails and echinoderms. Such creatures form the basis of the food chain in the ocean. Their distribution and diversity therefore affect many fish stocks and marine mammals.
The new underwater observatory, called Zooplankton-Observatory, can automatically detect the distribution patterns of microorganisms and particles with a high spatial-temporal resolution. It does this without having to extract samples or specimens from the marine environment. In addition, it can record the distribution and sink rate of small organic particles (also known as the “snow of the oceans”). Such particles are integral in the carbon fluxes in the oceans and therefore exert an influence on our climate.
This new device is a combination of an Acoustic Doppler Currrent Profiler (ADCP) and a Video-Plankton-Recorder (VPR). The latter is an underwater camera system that can capture 15-25 high-resolution images per second. This enables scientists to observe and identify organisms which are at least 0.5 millimeters in size (even the gelatinous plankton, which often goes undetected in traditional sampling methods). The ADCP provides a three-dimensional measurement of the flow field and measures the acoustic back-up level. With this information, the daily or seasonal migration patterns of zooplankton communities can be studied and migration rates can be determined.
The Zooplankton-Observatory was developed by Dr Boris Cisewski from the Thünen Institute of Sea Fisheries and Dr Klas Ove Möller from the HZG, with the help of specialist marine technology companies. At the end of November 2016, AWI's Center for Scientific Diving, with the help of the Tönning Water and Shipping Authority, brought it on board the marine pollution control vessel Neuwerk.
The Zooplankton-Observatory complements the underwater node system that was developed by HZG and AWI as part of the COSYNA (Coastal Observing System for Northern and Arctic Seas) at MarGate, AWI's underwater experimental facility off Helgoland. This underwater node is an underwater “socket” that provides power and Internet access underwater. It also offers the infrastructure to connect different sensor systems and devices together and operate them remotely on a short- or long-term basis. The node is operated by AWI scientist Professor Philipp Fischer, in collaboration with HZG. The Zooplankton-Observatory will complement the measuring instruments already deployed underwater and has the capacity to gather data for several months.
More information: www.awi.de