Expedition blogs and news from the Shallow Marine Surveys Group

Creatures big and small

Most of the group has now left southward, returning to the Falkland Islands. The remainder will leave tonight northward, to Great Britain - except for our two intrepid plant specialists, who will stay another 7 days.

During the expedition, we have recorded literally hundreds of marine species and taken more than 8000 photographs.

The largest species encountered and photographed was probably a group of bottlenose dolphins that accompanied the boat on the way to Boatswain Bird Island. But it is likely that the fin spotted near Boatswain Bird Island belonged to a much larger animal, a whale shark. Unfortunately, by the time we put on masks and fins it had already disappeared. A mention may also be made of the passing humpback whale several members reported seeing from the shore while filling tanks. The largest creature actually captured was certainly the hawksbill turtle which was tagged, measured and released from Georgetown pierhead.

[caption id="attachment_638" align="aligncenter" width="584"] A pod of bottlenose dolphins escorted the team to their dive site near Boatswain Bird Island.

At the other end of the scale, one of the smallest creatures recorded (and captured) must have been a tiny sea slug, belonging to a group called Sacoglossa. It lives on the green alga Bryopsis,where it is perfectly camouflaged. It was first spotted well after a dive while Kostas Tsiamis was examining a sample of Bryopsis under a microscope. Peter Wirtz then managed to find further specimens during subsequent dives.

[caption id="attachment_639" align="aligncenter" width="584"] This tiny sea slug is photographed crawling on the fingertip of Peter Wirtz. As illustrated by this image, it's very difficult to tell apart from the algae on which it lives.

- Article by Peter Wirtz

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What a Mess!

A team the size of ours needs a lot of fuel to keep functioning for day after day of multiple dives. During our stay in Ascension most of us have had the great fortune to be thoroughly spoilt by the fantastic staff at the Ascension Island Base Combined Mess at Traveller's Hill.

The food for the three weeks has been consistently great, with many team members eating far more than they really should have and we're sure several may be returning home carrying some extra kilos.

[caption id="attachment_627" align="aligncenter" width="584"] The mess is nestled in gardens with Green Mountain providing a backdrop.

As we all head north and south on the Airbridge to get home, we'd like to take this opportunity to thank the chefs and staff at the Mess for their excellent service, super food and infinite patience dealing with a mad rush of scientists (or maybe a rush of mad scientists) running in for food just minutes before the kitchens close.

And not forgetting the packed lunches we were supplied with every day which everyone looked forward to breaking open and bartering the various chocolate and crisps treats!

Thank you to the Traveller's Hill Mess from all the team at Shallow Marine Surveys Group.

[caption id="attachment_626" align="aligncenter" width="584"] The highlight of many a team member's day. The sight of the evening's menu after a long day diving.
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An expedition highlight

The team returns to Shelly Beach

We mentioned in one of our early posts that two of our team members had been fortunate enough to be shown a very special site here on Ascension, the small rock pools at Shelly Beach where two very rare and vulnerable species of shrimp are found.

Yesterday a large number of the team enjoyed a return visit to the pools, escorted by Stedson Stroud and Jolene Sim of Ascension Conservation. This time we were loaded with all the equipment we would need for a survey of the site, including underwater cameras, devices to measure salinity and temperature, GPS units to map the site and, most excitingly, special permission by the Ascension Island Government to collect a small number of samples for further study.

Enjoy this short gallery of images taken at this exceptional location.

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A trip to Mars

In 1877 a young astronomer, David Gill, travelled to Ascension Island in an attempt to calculate, with greater precision than ever before, the distance from the earth to the sun.

He was accompanied by his wife, Isobel Gill, who in fact was instrumental to the success of his expedition by finding the ideal site from which he could make his astronomical observations.

[caption id="attachment_568" align="aligncenter" width="584"] Mars Bay, Ascension Island, as seen from the sea. The Gill's camp site is just over the small rise in the foreground.

This site was named Mars Bay, as it was from here Gill could make his observations of the planet Mars which he could use for his calculations. The couple spent a number of months camped at this inhospitable location and the story of their time here was recorded and published by Isobel, giving a unique account of the experience.

The full text of Isobel Gill's "Six Months in Ascension. An Unscientific Account of a Scientific Expedition" can be found on-line here and a good summary can be read here. Additionally some downloadable versions are also available.

Team member Wetjens Dimmlich has been reading the book during the current expedition and enjoyed the opportunity to visit the site of the Gill camp where the pathways created and shells collected by Isobel Gill can still be found where they were left. Perhaps these images will help readers imagine the conditions the Gills worked under to make their own expedition a success.

[caption id="attachment_569" align="aligncenter" width="584"] Rocks line this pathway leading to the flat ground on which the Gills set their tents.

[caption id="attachment_571" align="aligncenter" width="584"] The path leading up from the beach to the campsite.

[caption id="attachment_570" align="aligncenter" width="584"] The path leading from the campsite down to the seashore.
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Evening in the Saint's Club

Last night the Ascension Island community were invited to a presentation by the team about their previous work in Falklands and South Georgia, as well as talks about the current expedition.

The talk was held in the Saint's Club, here in Georgetown, which is one of the centres of night-life in this small town. It's a great place to unwind at the bar, have lunch or watch a game of skittles!

Everyone enjoyed the images of undersea life, some of which have already been loaded to this blog as well as some detailed information about some of the methods we are using to capture some animals for further study.

Throughout our stay in Ascension the group has very much appreciated the great interest in the expedition by island residents. As we reluctantly prepare to leave soon, we remind all that anyone who would like to chat about the project will be most welcome to corner any member of the team while we're still here!

[caption id="attachment_559" align="aligncenter" width="584"] Paul Brickle introduces the talk with some information about the work of the Shallow Marine Surveys Group.

[caption id="attachment_562" align="aligncenter" width="584"] Peter Wirtz entertaining the audience with an impromptu talk about the various animals found in Ascension waters.

[caption id="attachment_561" align="aligncenter" width="584"] Simon Morley provides details about his settlement plate experiments.

[caption id="attachment_560" align="aligncenter" width="584"] Jude Brown explains the survey methods used by the team to count sealife underwater.


[caption id="attachment_563" align="aligncenter" width="584"] Frithjof Kuepper wraps up the presentation with some information about the search for new algal species.

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Oceanography studies

Ascension Island – a lonely piece of land in a seemingly borderless ocean turned out to be the centre of an oceanographic 'collision'  which does not happen very often in featureless seas. Here, the central branch of the Southern Equatorial Current that normally goes on surface meets the Southern Equatorial Counter-Current that normally goes in subsurface layers but right here, between 7 and 8°S, it travels to the surface. Interactions of these two streams give rise to high water turbulence, numerous gyres and eddies and other kinds of water unrest. Those, combined with upwelling areas in inshore waters caused by the bottom topography, are responsible to the high productivity of the area that attracts numerous large predators close to shore that might be seen filleted on Georgetown pier almost every night.

[caption id="attachment_547" align="aligncenter" width="584"] Getting picked up by our research vessel for the circumnavigation of the island, the Queen of Atlantis.

To study the local oceanographic features, a total of 16 oceanographic stations with manually deployed CTD (Conductivity – Temperature – Density) devices were carried out. To complete the picture around the island, Vlad Laptikhovsky, Steve Cartwright, Wetjens Dimmlich, Frithjof Kuepper and Kostas Konstantinos circumnavigated Ascension in the comfort of the Queen of Atlantis. Generally conditions in the voyage were good but did become quite rough along the more exposed coast near Boatswain Bird Island.

The results reveal a complicated oceanographic structure even in the upper 50-m layer, where waters of both the major oceanic currents combined with a mixed layer of local origin.

[caption id="attachment_548" align="aligncenter" width="584"] Vlad deploying the CTD during the 4-hr trip around Ascension.

During the past two weeks the interaction of these currents was quite mobile. The cold productive Counter-Current eventually occupied the surface layer around most of the island, excluding the small offshore part in the north around English Bay. The more saline (because of evaporation) Equatorial Current moved its water mostly deeper than 20 m revealing expected phenomenon of temperature increase with depth, and surfaced only in the very north of the studied area.

- Contributed by Vladimir Laptikhovsky

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