Expedition blogs and news from the Shallow Marine Surveys Group

Team member's link to the past?

Visitors to Ascension can't fail to notice two large white naval guns mounted at Fort Bedford, overlooking Georgetown and Clarence Bay. The guns are 5.5-inch guns removed from HMS Hood in 1934 and are the only remaining parts of this ship which was (in)famously destroyed by the German ship Bismarck with the loss of all but 3 lives.

[caption id="attachment_651" align="aligncenter" width="584"] The pair of 5.5 inch guns removed from HMS Hood stand guard over Georgetown.

The only action these historic weapons saw during World War II occurred on 9 December 1941. At around mid-day, the U-boat U-124, commanded by Johann Mohr, approached Georgetown on the surface with the intention of sinking any ships at anchor or shelling the cable station. The submarine was fired on by the two-gun shore battery but no hits were scored. However the shelling was accurate enough to force the U-boat to submerge and retreated. Details of the action can be found here.

[caption id="attachment_653" align="aligncenter" width="584"] The interior of one of the guns. Both are still largely intact and a visit to see them offers great views across Georgetown and the bay.

In a very intriguing twist, an examination of the U-Boat crew lists shows an engineer by the name of Rudolph Dimmlich was serving on the U124 at the time of the attack. One of our team members, Dr Wetjens Dimmlich, shares this uncommon name and it is not out of the question that the only time the guns were fired were an attempt to sink a vessel that a relative of one of our team members was serving on!

[caption id="attachment_652" align="aligncenter" width="584"] Wetjens (perhaps?) making contact with a piece of family history and linking the current expedition with events that took place in Georgetown's past.


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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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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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Back to school!

This morning Drs Judith Brown and Wetjens Dimmlich woke early to go back to school. They travelled up the hill to Two Boats school to show the children there a selection of images from Shallow Marine Survey Group's work in both the Falkland Islands and the current Ascension expedition.

[caption id="attachment_441" align="aligncenter" width="584"] Jude speaks to a full room during morning assembly.
Image: W Dimmlich

Jude spoke to the entire school who were gathered in the gym and managed to maintain the interest of all ages during her talk. She showed images of different species of animals found in the cold Falkland waters and the tropical Ascension waters and challenged her audience to pick which came from where.

She also described our unsuccessful attempts so far to entice an unidentified shrimp from his hole and received some very useful tips for the audience on how to entice the creature from its burrow. During the drive back to the Conservation offices we had some discussion about finding a source on the island for parsley!

[caption id="attachment_442" align="aligncenter" width="584"] The kids enthusiastically offered suggestions on how to capture elusive sea creatures.
Image: W Dimmlich
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Boatswain Bird Island

On Sunday 26th August, most of the team had a break from the intensive diving of the first week on the island. Team members dispersed to all corners of Ascension but Dr's Pieter van West, Vladimir Laptikhovsky and Wetjens Dimmlich elected to take the 4 hr round trip hike to Letterbox, a vantage point at the eastern-most point of Ascension Island. This location offers magnificent views along the coast and over Boatswain Bird Island, an inaccessible rock about 300m from Ascension.

The hikers were met at the start of the walk by low clouds and strong winds driving rain over the mountain and had to make the decision whether to attempt the long walk across the inhospitable lava fields. However, the indomitable Vlad Laptikhovsky, echoing the words of another famous Russian pioneer, Yuri Gagarin, "Let's go!" encouraged the rest of the small group to grit their teeth and set forth into the white-out conditions.

(It may also be that the same words were used by Captain Scott in the Antarctic).

Along the way the group were alternately hot, cold, wet and dry but the effort was rewarded by stunning views of Boatswain Bird Island before the weather closed in yet again.

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Ascension 21/08/12

Day Two

Most of the team have now arrived on Ascension and are getting straight into work. Yesterday (Monday 20th August) new arrivals were somewhat groggily taking their first dives just hours after touching down on Wideawake Airfield. First order of business was trialling the sampling methodology for transects along the seabed during which species counts would taken.

[caption id="attachment_303" align="alignleft" width="584"] Dr Judith Brown gives a rundown of safety guidelines for the team to follow while diving in this remote location.
Image: Pieter van West

These early dives were done in English Bay, a sheltered beach with easy access and relatively calm waters so everyone could check out their gear and make sure all was in good working order. The weather was overcast with passing showers, but occasionally the sun broke through in full tropical strength.

Under the direction of Dr Simon Morley some team members also began to set up the lab in the offices of the Ascension Island Conservation Dept. complete with collapsible aquaria for climate change experiments. We still need to address the issue of transporting fresh seawater to the office everyday to keep the experiment running over the 3 weeks. Today, Simon and Dr Wetjens Dimmlich embarked on a scavenger hunt around the island following any rumour of containers which might hold water. Eventually, after scouring the local rubbish tip unsuccessfully they had to give up and now need to work on a new plan for getting water to the fish tanks.

[caption id="attachment_316" align="alignleft" width="300"] The boiler of the Derby, sunk in 1929.
Image: SMSG

This morning’s dives were on the wreck of the Derby, a steel hulled steam trawler which was used to transport guano from Boatswain Bird Island.  She was moored in English Bay but sank together with other small vessels during heavy rollers in January 1929. She lies off a reef in about 9m of water and involved more transect work and also photography of marine life near the wreck. This proved challenging in the swell, and was made more difficult by the countless urchins found in almost every crevice so any handholds or potential spots to kneel had to be carefully considered before committing yourself to it. In the meantime the subject generally decided not to wait around and had swum away. It’s likely that capturing images of the fish life is going to prove quite a lot more frustrating than anticipated.

[caption id="attachment_620" align="aligncenter" width="584"] The bow section of the Derby.

While other team members were either diving or driving around Ascension in futile quests for water containers, Dr’s Pieter van West and Alexander Arkhipkin enjoyed a very memorable tour by Jolene and Natasha of Ascension Island Conservation. Shelly Beach is a location accessible only by 4wd vehicle and a half hour hike through a lava field. This used to be the site of a large sooty tern colony numbering in the hundreds of thousands of birds, but this was wiped out by feral cats. Rock pools are found here, separated from the sea by 100m of lava platform but replenished with seawater through underground fissures. These pools appear to contain ecosystems probably found nowhere else. Of particular interest are two unique species of shrimp (Procaris ascensionis and Typhlatya rogersi) living in these interconnected network of rock pools.

[caption id="attachment_305" align="alignleft" width="584"] Procaris ascensionis, one of the extremely rare and protected species of shrimp found only on Ascension Island.
Image: Pieter van West

It may be that the shrimp are the most vulnerable species on the planet, found only in these pools and only on Ascension Island and are completely protected to the extent that we are only permitted to look but not touch. In addition to the shrimp Peter noticed other distinct species of algal and invertebrate life which may be worth further investigation. Unfortunately this visit to the rock pools was only a short one as the main object of the excursion was to collect oysters required for another study. A return visit to these pools will no doubt occur later in the trip with the underwater cameras to collect a full record of the species existing there.

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