Research Cruise

 

Winds NW at 15 knots, seas calm 

S 45° 21.90′ E 144° 37.62′ – The Tasman Fracture Zone

So we dove last night on the Tasman Fracture Zone, descending to 4,000 meters – that’s 2.48 miles below the sea surface!  It took us about 2 hours to get down to our lowest depth yet – 4010 meters.  This is also a completely unexplored feature – excitement was in the air when we finally made it to the bottom!  Unfortunately, there really weren’t any Dianthus to speak of in the almost 2,000 meters of relief we covered on this dive, save for one isolated pocket of fossil solitaries…the community was incredibly sparse, and dominated mostly by barnacles, some octocorals and gorgonians, and invertebrates like prawns/shrimp, sea pens, and sea cucumbers.  We did see a carnivorous sea squirt though…basically an underwater Venus fly trap – but MUCH bigger!  So, overall, a pretty uneventful dive in terms of coral catch, but some cool biology!  The geology was fascinating too – the sediment was incredibly fine and lightly packed; it made me think of powder snow.  There were many fresh rock faces as well; it could be that rocks fall from higher up on the cliff often enough that a stable community cannot form, and thus leaves lots of open real estate.  There is another hypothesis as to the dearth of life – it could be that although this water is very rich in inorganic nutrients, there is no primary productivity in this part of the ocean.  This only happens when this nutrient-rich water hits this cliff face and gets rushed upwards, where the clorophyll at the surface utilize these nutrients, die, and then rain down over the ocean just to the east of the fracture, over the Tasman Rise.  

We’re currently calling the dive short due to the lack of fossil corals, and heading over to the Finger-knob region, where we tried to dive earlier in the cruise.  We have ABE photos of this area from last year’s cruise, and it shows a very coral-rich environment, and a thriving community overall – our weather window opened up a bit, and since we know fairly accurately where to look for our fossil corals, we should be able to collect a large sample over a short period of time.  We’ll be in the water around 10 AM tomorrow, and come back out at midnight, just as the low pressure system starts to head in from the Southwest.  Then it’s time to do some CTD casts and collect some trace metal isotope data- more to come on that!  

Also – thanks to everyone’s comments and holiday – I’m glad people are reading and taking interest – and keeping track of friends and family!  Only a week more to go…