Expedition blogs and news from the Shallow Marine Surveys Group

Thank you Ascension

Although all the team have now departed Ascension, loaded down with samples and countless photographs, the work will continue long after our stay on the island.

With an entire upcoming edition of the Journal of the Marine Biological Association of the UK to be dedicated to the results of this expedition there is a tremendous amount of work to be done in order to meet publishing deadlines.

With this ahead of us, the Shallow Marine Surveys Group would like to take this opportunity to extend our deepest gratitude and appreciation to the Ascension Island Government and Administrator, Colin Wells, for their enthusiastic support and keen interest in this ambitious undertaking.

[caption id="attachment_676" align="aligncenter" width="584"] The Ascension Island Government building in Georgetown.

Additionally we would also particularly like to thank Ascension Island Conservation Department for making their facilities available to us, despite the chaos and interruptions we brought to their daily lives.

We hope that we will be able to continue collaborating so effectively on the longer term projects we leave behind and also in the future on any further on site surveys.

[caption id="attachment_678" align="aligncenter" width="584"] The team took over sections of the Conservation offices during their stay on Ascension. Thank you to all for your hospitality!

With the SMSG team now dispersed around the globe, there will be no more blog posts from the island.

However over time, as work continues on the material we compiled, we'll be occasionally updating the blog with news items. In particular we aim to include galleries of all marine species we photographed as the identification work progresses on the thousands of images we now have.

And of course, future expeditions by SMSG will be announced and documented here. Stay tuned - no doubt there are more exciting developments to come!

Farewell Ascension from the entire SMSG team and thank you!

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Hunting seaweeds around Ascension

We – Kostas and Frithjof – are the 2 botanists in the team, and we have been trying to assess and capture as much of Ascension’s diversity in terms of seaweeds (macroalgae) as possible during this expedition. Due to a clash of timing with other, similar work in Greece in August, we only came here on Sept. 3, but we are also staying about 9 days longer than the other team members.

The first thing that strikes any diver is that Ascension has a heavily fish-dominated coastal marine ecosystem. Most of the seabed looks rocky without any seaweeds. So where are the algae?

Well, there must be algae in the system – they ultimately produce the biomass and energy to sustain this impressive abundance of animal life. It is not clear at the current time what respective contributions benthic and planktonic algae make to sustaining the coastal marine food web, but it is obvious that the turnover of algal biomass in either case has to be very high. In other words, they probably grow very fast, and they also get eaten (grazed) very fast.

The most common fish species around Ascension is the black triggerfish, which is omnivorous – which means that it also grazes most types of fleshy seaweeds. This species is clearly one of the main suspects for grazing most seaweeds to (almost) invisibility.

[caption id="attachment_665" align="aligncenter" width="584"] Grazing black triggerfish. Just in a footnote, we also witnessed cannibalism by Black Triggerfish, they even eat their own, dead mates

[caption id="attachment_666" align="aligncenter" width="584"] Sleeping black triggerfish.

Still, despite the voracious triggerfish, we found a rather rich seaweed flora, just over 70 species in about 2 weeks of intense searching and collecting, including almost 20 new, previously unrecorded taxa. Most of them are either very small (in the open sea around Ascension) due to the strong grazing pressure, typically occurring in small turf-like mats. Larger seaweeds can only be found in places were grazers can’t fully exert their pressure – in particular, in intertidal rock pools and in swell zones.

[caption id="attachment_667" align="aligncenter" width="628"] The green alga Neomerys in a coralline community.

There is one exception to the above – calcareous red algae (coralline red algae) actually dominate much of Ascension’s seabed ecosystem, covering large surfaces and constituting structuring elements to the seabed communities and landscape. Due to their solid calcium carbonate skeleton, they are unpalatable to grazers, and they somewhat fulfil the reef-building role that corals play in many other tropical marine areas around the world. They either form loose piles on the seabed (maerl - rhodoliths), or beautiful, tower- or coral-like, reef-forming structures. Corals have indeed a very cryptic existence around Ascension, and it is not clear to date why that is the case. There are only few experts for coralline red algae in the world (neither of the 2 of us are). We will join forces with two of them, Rafael Riosmena-Rodriguez in Mexico and A. Athanasiadis in Sweden, for identifying the many samples of coralline red algae collected during our dives.

[caption id="attachment_668" align="aligncenter" width="628"] Coralline red algae forming tower- or reef-like structures during a night dive in English Bay, Sept. 4

Time and facilities during expeditions like this one are always severely limiting factors. In other words, a visiting investigator may easily miss some of the algal biodiversity in a place like Ascension either because it is too small, or outside its growing season. For this reason, we have collected many substratum samples (fragments of sea shells, sand, coralline red algae) in sterile tubes which will be incubated under suitable culture conditions in the laboratory of Frithjof’s friend Akira Peters in Roscoff. Over the following months, Akira will monitor them for algal outgrowth and obtain unialgal isolates (i.e. only one algal strain at a time). By experience, this approach captures a number of taxa usually inaccessible or unavailable during the fieldwork. Our list of around 70 macroalgal taxa around Ascension may still get longer for a while after returning to Europe!

- Contributed by Frithjof C. Kuepper (Oceanlab, University of Aberdeen, Scotland) & Kostas Tsiamis (Hellenic Centre for Marine Research, Greece)

Recent Comments
Guest — Sue Scott
Excellent to see such good work on the seaweeds, & their importance highlighted - they usually get forgotten in favour of those bo... Read More
Wednesday, 19 September 2012 12:12 PM
Guest — Rafael Riosmena
I deeply like this information and the lovely rhodolith/maer beds from Ascencion....!!!
Wednesday, 16 January 2013 1:01 AM
Guest — Dave John
Great to see underwater photos of this very unusual submarine environment where the ubiquitous black trigger fish have such an imp... Read More
Saturday, 31 August 2013 10:10 PM
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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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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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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.

[gallery orderby="title"]
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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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