The fate of cetacean carcasses in the deep sea was investigated using autonomous deep-sea lander vehicles incorporating time-lapse camera systems, ¢sh and amphipod traps. Three lander deployments placed cetacean carcasses at depths of 4000^4800 m in the northeast Atlantic for periods of 36 h, 152 h and 276 h before being recovered. The photographic sequences revealed that carcasses were rapidly consumed by ¢sh and invertebrate scavengers with removal rates ranging from 0.05^0.4 kg h 71. In the longest experiment the carcass was skeletonized within ¢ve days. In each deployment, approximately an hour after emplacement, the grenadier Coryphaenoides (Nematonurus) armatus and large numbers of lysianassid amphipods had arrived at the food-fall. The initially high numbers of grenadiers declined once the majority of the bait had been consumed and a variety of other ¢sh and invertebrates were then observed, some taking up residence at the site. None of the ¢sh species appeared to consume the carcass directly, but preyed upon amphipods instead. Funnel traps recovered with the carcass indicated a succession in the species composition of amphipods, with the specialist necrophages such as Paralicella spp. being replaced by more generalist feeders of the Orchomene species complex.
Deep-ocean landers are autonomous vehicles that descend to the sea floor and function autonomously without any connection to the surface for periods of 12h to one year. At the end of the mission, ballast is released by acoustic command from the surface and the lander ascends by virtue of its buoyancy. Landers are made up of two components:1. Basic delivery system. 2. The scientific payload.Experience with over 20 lander types within Europe has established some common design principles. The Aberdeen compact ATTIS' lander combines experiment management, data storage, acoustic telemetry to the surface and ballast release control all within one unit. More typically a modular approach is used with the delivery system separated from the scientific payload. The scientific payload has its own power supply and different experiments on the same lander are autonomous so that failure of one does not affect the rest of the system. A modular architecture with the ability to change scientific payloads has proved most flexible and reliable. A CAN type network provides central data logging whilst maintaining functional autonomy of the different experimental modules.
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