Saturday, 15 December 2012

5 - ROV-ing at E2

Over the last four days, we have completed three ROV dives at the E2 site (refer to map). We have split this site into two areas – north and south. The south is the area we have explored on previous cruises and thoroughly over the last few days. The north is a poorly-known site where strong signals of hydrothermal activity have been picked up previously with the CTD, however no ROV exploration has been done as yet.

At E2 South, we have been using distinct features of the terrain to navigate (in a similar way to using sign posts when driving). We always start our ROV dives at ‘Dog’s Head’. This is the only black-smoker complex that we know of at E2 and was found in 2010. There are bacterial mats, anemones, yeti crabs, gastropods, limpets and sea spiders living on this chimney complex.

Image of the black-smoking Dog’s Head with bacterial mats
(Rogers et al., 2012).
Moving south from ‘Dog’s Head’, there are a series of chimneys, some extinct and some emitting diffuse flow with limited fauna. The names given to these sites range from ‘Poached Egg’ to ‘Cricket Stumps’ and take inspiration from what they resemble.

There are six other areas of interest at E2 South – ‘Sepia’, ‘Cinderella’s Castle’, ‘Dreaming Spires’, ‘Crab City’, ‘Crab Spa’ and ‘Anemone Field’. Sepia is a chimney that rises off the seabed and then balloons out into a large spherical structure with lots of flanges. It looks like a giant button mushroom. This is probably the area with the second highest abundance of fauna at E2.

Image of a flange at Sepia with anemones and bacterial mats on
the chimney below (Rogers et al,. 2012).
‘Cinderella’s Castle’ is another diffuse-flow chimney that balloons towards the top into a structure with flanges, but this time, there are many smaller chimneys on top (like the turrets of a castle- called chimlets). This site also has the full complement of vent fauna, similar to ‘Dog’s Head’ and ‘Sepia’. ‘Dreaming Spires’ is very similar to ‘Cinderella’s Castle’.

Image of the undescribed gastropod from E2 surrounding one yeti crab.
There are also limpets on the gastropods, anemones  and one sea spider (bottom right)
(Rogers et al., 2012).
‘Crab City’, ‘Crab Spa’ and ‘Anemone Field’ are all diffuse-flow patches amongst pillow and rope lava. ‘Crab City’ is a large aggregation of yeti crabs and bacterial mats found in 2010. ‘Crab Spa’ is a series of smaller patches of yeti crabs, which were found on this cruise. We originally thought of naming it ‘Crab Holiday Park’ but decided ‘Crab Spa” had a nicer ring to it! ‘Anemone Field’ is pretty self explanatory – a large flat-ish area with lots and lots of anemones.

We have managed to get many biological and chemical samples from the E2 South site and the ‘Hows’ and ‘Whats’ of that will be a coming blog entry.

Over tonight and into tomorrow, we intend to send ROV Isis  down to explore the E2 north site. Fingers crossed we find something exciting!

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