The mid-sized RMT (RMT8) has a mouth opening of eight square metres and mesh of 5mm. The smallest version of the RMT net system (RMT1) has a one square metre mouth opening, with 330 µm mesh and is mainly used to catch mesozooplankton. This pelagic trawl system is available in different configurations for specific scientific requirements. The RMT systems are are operated in combination with the down-wire net monitor system giving real-time control and also identifying the environmental conditions (temperature, salinity and depth) of the water where it is deployed. When deployed from the RRS Sir David Attenborough, the RMT can reach 2000m. This allows targeted sampling in specific swarms or water layers. The Rectangular midwater trawl (RMT) system consists of two nets of the same size, which can be opened and closed independently. A small CTD to collect data on the water depth, temperature and salinity.A deep-water camera system custom-built for BAS, allowing researchers to monitor each tow in high-resolution colour imagery.The epibenthic sledge can be equipped with additional equipment including: The sledge can be deployed to depths of 8000m. The sledge also has doors that close during the journey up or down through the water column, ensuring sampling only occurs when the sledge is on the seafloor. A bucket at the back of the sampling net catches the animals safely. As the sledge passes over the seafloor, it stirs up the top layer of sediment and collects species which live just above the seafloor. Photograph by Rob Larter (British Antarctic Survey) Epibenthic sledgeĪn epibenthic sledge has a finer net than the Agassiz trawl to collect smaller organisms. Recovery of the Agassiz trawl onboard the RRS James Clark Ross in the Amundsen Sea. The Agassiz trawl consists of a metal frame that pulls a long net which collects samples of organisms living on or just above the seafloor. Because it has no electronic or pressure-sensitive components and is very stable and robust, it can be deployed to depths of several thousand metres with the RRS Sir David Attenborough’s ability for deep trawl, it will be used to depths of 8000m. The Agassiz trawl is a device for collecting samples of mega and macrofauna. BAS owns a number of bespoke nets, trawls and sledges that can be deployed from the RRS Sir David Attenborough to sample ecosystems in the water column and on the seafloor.
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