With a region of low pressure being predicted for today the whole ship was expecting stormy weather that would have rendered science onboard particularly limited but today the sun has been shining and the stillness of the ocean has been notable….
As a result today has been action packed! First thing this morning the deep sea trawl (OTSB) arrived on deck giving all the enthusiastic scientists a long day of processing with many exciting moments as different species which lie beneath were brought to our attention. With numerous invertebrates and fish species being preserved in order to provide specimens which will allowi people not lucky enough to be at sea to enjoy the beauties of the deep.
A typical day of processing involves a convey belt like system… Nikki King orchestrates the deep sea fish processing like a military system. Initially each individual fish is assigned a number, a wet weight is determined and the fish are measured (total body length, standard length, head length and pre anal length). Each fish is then cut open and the liver, stomach, and gonads (reproductive organs) are weighed. Then using a scaled system the stomach is rated for fullness and the gonads are rated in terms of how developed they, the somewhat eviscerated fish is then passed onto the other members of the convey belt. Tissue samples of muscle are removed and in the case of a few fish the liver, gonads, stomach are preserved for sampling when back on dry land. After all this has occurred the fish are then passed on in order to have their otoliths removed. This process involves making a cut just behind the eyes of the fish an ideal cut removes the top of the skull, revealing the full length of the soft white brain underneath. Push the rear of the brain to one side, or cut it out all together. The large pair of otoliths should be visible underneath the rear of the brain, remove these with a pair of tweezers. Fish otoliths accrete layers of calcium carbonate and gelatinous matrix throughout their lives, by counting the rings it is possible to determine the age of the fish in years.
The amphipod trap has also been recovered; this is a way of being able to investigate the many different species that reside in the deeps recovering entire individuals. Allowing us to see whether there may differences in amphipods in the deep sea examples compared to other water depths as well as to see first hand the gigantism reported in many papers regarding this topic.
The megacorer has also been sent down to the deeps, this actively takes samples of the sea bed and return these to the vessel, thus allowing the composition of the ocean floor to be studied.
The PAL lander was recovered and im sure when the photo’s are analysed it will shed light on what fish species are present at different times during food falls to the deep ocean.
Also the shrimp camera was deployed transecting the summit of the mid Atlantic ridge, this allows us to see (in real time) from the vessel what the seafloor is really like.
All in all, everybody has had a busy day and were all rewarded with the usual Saturday night curry! (which is always exceptional!)
Sat 11th August