Sea cucumbers, carnivorous sponges and other deep sea creatures

by ZSL on

ZSL's Chris Yesson, Mona Fuhrmann and Stephen Long have returned from a two-week research cruise to explore the deep sea bed in West Greenland. In their second blog, they explain more about the species they discovered and why the habitats need to be protected. 

Biodiversity in the dark depths of the ocean
There was high biodiversity even in the dark depths of the cold ocean

The survey was a joint venture between the Greenland Institute of Natural Resources (GINR) and ZSL, with the scope of providing knowledge on benthic habitats in areas of Marine Stewardship Council (MSC) West Greenland Coldwater Prawn Fishery. 

We got as far as to the ice edge, which then prevented us to reach some of the targeted stations. However, we collected plenty of images at stations further south and we are excited to compare these to historical images from the 80s. We were lucky to re-encounter a rare deep water carnivorous sponge, Chondrocladia gigantea, at a depth of 445m, which we already spotted once in 2016 as the first observation ever made in Greenland waters. 

We tested a new custom made video sled, which is basically just a GoPro and two torches in underwater houses, mounted on a sled which can be dragged behind the boat.

A custom-made video sled captured more mobile species, such as crabs and fish
A custom-made video sled captured more mobile species, such as crabs and fish

It allowed us to cover larger areas and capture more mobile species, such as crabs and fish. Eelpouts, redfish and wolfish were often seen lingering between sponges, corals and feather stars. We also discovered a pristine soft coral garden at 400m and were amazed by such biodiversity in the dark depths of the cold ocean. 

Even at depths beyond 800m, we frequently encountered tubeworms and sea cucumbers that burrowed in the soft sediment, filtrating sea squirts which attach to small stones and pink sea anemones which may cover entire stretches of sea floor. 

Pink sea anemones
Even at depths beyond 800m, we encountered deep sea fish (Grenadier) captures on video

We know that extensive trawling has impacted the habitats of west Greenland, but there remains many beautiful and diverse habitats to discover. Our images of the sea bed demonstrate there are habitats worth of protection and our close collaboration with Sustainable Fisheries Greenland has seen gear changes that reduce impact of fishing on the sea bed.

The team will embark on another journey to areas of halibut fishery off the shelf of West Greenland in September. The Greenland halibut has recently entered the MSC sustainability scheme, yet little is known about the benthos inhabiting these great depths. We are hoping to gain insights using the new video sled which has proven successful on this trip.

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