The amphipod traps

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One of two amphipod traps, attached to the legs of the lander.

Author: Milena Wales

Amphipods are the first visible sign of scavenger activity at our bait during every deployment. We suspect they were the only happy customer of the Abyssal Eats Restaurant (TripAdvisor review in an earlier blog by Rob) since they could get up close and personal with the tuna underneath the plate.

As they are generally tiny, it is impossible to identify them to anything other than a generalisation “amphipods”. The only one we could identify to species level was the giant amphipod, Alicella gigantea. To get a better idea of which amphipod species live in the area, we need to catch them.

As we did not carry amphipod traps with us, it was my job to design them. I’d settled on the design described in the Porcupine Abyssal Plain Observatory’s blog post.  Theirs comprised of clear perspex cylinders with two funnels attached leading into the trap chamber, where a bait was secured to a mesh lid. As luck would have it, the crew on Sonne in unbelievably skilful at making anything out of almost nothing. Volker – who devised the ladder protection for our lander earlier – built 2 very similar traps out of what he had to hand – a length of plastic pipe and some kitchen funnels. Once we placed some juicy tuna chunks inside, we secured the netting using hose clamps.

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One of the few amphipods found inside the traps after deployment

The traps were originally supposed to go down on the last planned deployment (#11), however, we knew there may not have been enough time for that. Erring on the side of caution, we put them on for the penultimate deployment (#10)- we could then check if the design worked and possibly re-deploy if the scavengers were not distracted from too much choice of tasty smelling tuna.

Unfortunately, the maze-like trap design proved unpopular, compared to the easily accessible food on the bait plate, or perhaps the amphipods unsuccessfully tried to get in through the back of the traps – we won’t know this. We collected approximately 20 individual amphipods to take home for identification. As the cruise was coming to an end and the last lander deployment was cancelled, so there was no chance to redeploy the traps either. Perhaps if we had more time, we could have devised a mini amphipod-trap lander – may be next time.

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