Creating Artificial Jellyfish

The benthic boundary layer is the layer of water above the sediment which is important for the  biogeochemistry of the oceans as it is the site of significant organic matter cycling.   The effect of the deposition of jellyfish carcasses on the seafloor and the benthic boundary layer is unknown however, it is thought that the presence of jellyfalls, particularly large falls, will induce a change in benthic boundary layer flow dynamics.

The Jelly-Farm Project is setting out to test whether the physical presence of jellyfish carcasses will induce "skimming flow" in the benthic boundary layer.  Skimming flow is when fluids find it easier to flow over rather than around objects.  It is thought that skimming flow over jellyfish carcasses would result in a thicker diffusive boundary layer and a reduction in oxygen flux to the sediments.  Such an impact would significantly affect organic matter cycling on the seafloor.  

In April flume experiments will be conducted to simulate and provide initial results to determine the effect of relatively small, medium and large jellyfalls on the benthic boundary layer.
 Today prototypes of artificial jellyfish carcasses were created in the lab at IRIS.  

Test materials for making artificial jellyfish carcasses. 

A disney ball used as a mould for an agar artificial jellyfish.  A screw is used as a weight to keep the jellyfish anchored to the sediment during the flume experiments.  

A smaller jellyfish mould prototype with washer weight. 

Scavenger Lander and Sediment Trap Release Disabling, Lurefjorden and Masfjorden, Norway.

Scavenger trap

The scavenger lander surfaces on Thursday morning in Lurefjorden.  

Mark deploying the acoustic release head in Masfjorden.  

Returning to Seim after disabling the release on the sediment trap in Marsfjorden.  

Captain Leon disembarks the latest research vessel used in the JellyFarm project.  

Scavenger Lander Study, Lurefjorden, Norway.

The scavenger lander heading to the sea floor for its second deployment in Lurefjorden (Photo by Mark Berry). 

Kathy baiting the scavenger trap to learn if hagfish are present in that area of Lurefjorden.  

An example image from the scavenger lander.  We were happy with image quality produced by the camera and strobes.  

Scavenger Lander Deployment, Lurefjorden, Norway

The scavenger lander was deployed in Lurefjorden today at 11:00 and reached the seafloor at 441m 15 minutes later.

A fresh Periphylla. periphylla was caught in la arge drop fishing net just before the deployment to set as bait on the lander.

The completed scavenger lander ready for loading onto Solvik

Lander being loaded onto Solvik 

Preparing the drop net to collect jellies to bait the scavenger lander 

Preparing to leave Seim in the morning

Sailing into Lurefjorden 

Solvik departing to disable the sediment trap release in Lurefjorden on Monday evening 

The scavenger bait plate is deployed with a single jelly

Scavenger Lander Assembly, Askøy, Norway.

At Askøy today the deep-sea time lapse stills camera (rated to 6000 m) from Ocean Imaging was attached to the lander frame using a heavy duty clamp.  The camera is orientated looking straight down at the bait plate as this will enable us to measure the length of animals feeding on the jellyfalls.  The size of scavengers will affect their metabolism which is important for understanding the role of scavengers feeding on jellyfalls in the carbon food web.

Camera clamp

 Strope lights are attached either side of the camera and will flash everytime the camera takes an image.

Cutting steel wire for the bait plate

The bait plate is attached using a flexible wires so that it will move up onto the seafloor surface when the lander sinks into the muddy layer on the fjord floor.

Planning for next weeks cruise

Scavenger Lander Assembly, Askøy, Norway.

Today at Solvik´s workshop the lander floats, the computer and camera were attached.

The lander sinks during deployment because it is negatively buoyant due to 12 x 17 kg steel weights. When we want the lander to return to the surface, to retrieve the images of the scavengers feeding on the jellyfalls, an acoustic signal is sent to the release units which causes a catch to open releasing the cables holding the weights.  The weights are then released, making the lander positively buoyant due to the floats.  The lander then rises to the sea surface where it can be returned to the ship.

Lander floats being attached 

Camera computer to control image recording sequence. 

Scavenger Lander Cruise Preparation, Askøy, Norway.

Kathy Dunlop, Mark Berry and Leon Pedersen prepare the benthic chamber lander for deployments as a baited scavenger lander.  The scavenger lander will be tested next week in Lurefjorden and also used as part of a study to examine the affect of fjord water depth on scavenger jelly-fall feeding dynamics. 

Lander floats being checked to ensure no damage    

Lander weight lifting 

A useful helper stops by

 

The lander being assembled