SMSG Blog

Expedition blogs and news from the Shallow Marine Surveys Group

Our day in court

Yesterday, Drs Paul Brickle, Jude Brown and Simon Morley gave a talk about the project to a gathering held in the Ascension Islands magistrate's court.


The island's Administrator, Mr Colin Wells, attended along with other Ascension Island government representatives including councillors, service heads, Ascension Conservation members and the RAF base commander.




[caption id="attachment_430" align="aligncenter" width="584"] Paul Brickle presenting the work of the Shallow Marine Surveys Group, while Simon Morley and Jude Brown wait for their turn in the spotlight.
Image: W Dimmlich

After the talk the team was very grateful for the words of support offered by the audience and the enthusiasm with which the work was received as well as a desire for the continuation of studies of the marine environment by local participants in the future.




[caption id="attachment_431" align="aligncenter" width="584"] Simon explains the objectives and methods used in his climate-change related experiments carried out during the expedition.
Image: W Dimmlich


 
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Studying Sally lightfoot

[caption id="attachment_409" align="aligncenter" width="584"] The Ascension Island crab, Grapsus adscensionis.
Image: W Dimmlich

Nicknamed “Sally lightfoot” by sailors, there are two crabs of the genus Grapsus which have chosen the tropical eastern parts of oceans as their habitat. One of them, G. grapsus, settled along the Pacific coasts of America and made the long jump to Galapagos where the local population impressed Charles Darwin with their agility and capacity to avoid sailor hands. Apart from their impressive acceleration from a standing start, another notable characteristic is that they perform a valuable service to marine iguanas by removing ticks from them, similar to the role played by cleaner shrimps with fish.




[caption id="attachment_416" align="aligncenter" width="584"] The crabs can be seen clustering on the lava platforms in all sizes.
Image: W Dimmlich

The second species, G. adscensionis, inhabits the east Atlantic and in the historical past also made a long jump - to Ascension and St. Helena islands. The crab inhabits the splash zone though at night they ramble the sand dunes of the island as some ten-legged hosts. Nothing is known about their biology on this spearhead of their westward expansion of the species range (do they target South America as much as Spanish conquistadors?). In respect to feeding habits, for example they were seen to be feeding on a scientist's sandwich as well as witnessed kidnapping a baby green turtle. It is not exactly what Grapsus do with reptiles on Galapagos… However, neither sandwiches or turtle hatchlings could hardly be considered as a staple throughout the year.




[caption id="attachment_408" align="aligncenter" width="584"] Steve Brown and Vlad Laptikhovksy attempting to catch the very speedy subjects of the investigation.
Image: W Dimmlich

Steve Brown challenged the project to study the reproductive biology of the species, particularly size at maturation and fecundity on Ascension Island. The idea is to compare this information with available data on continental populations of the species, as well as with those on G. grapsus from both the American continent and Galapagos (which are pretty much a "Pacific Ascension") and to reveal how this harsh islands’ environment impacted reproductive features. Because of our intensive diving schedule, the sampling usually occurs every day while tanks are being filled. It takes about two minutes for a crab to be caught, measured all across, sexed, cursed for its strong claws and scratchy pointed legs and released back to the shoreline. Some females however are deprived of their broods that would be further investigated in the lab.




[caption id="attachment_414" align="aligncenter" width="584"] Measuring carapace dimensions of G. adscensionis, while keeping careful hold of the claws!
Image: W Dimmlich

Contributed by V. Laptikhovsky

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Hawksbill tagging underway (well, nearly)…

[caption id="attachment_392" align="alignleft" width="300"] Sam Weber instructing volunteer turtle catchers on the finer points of the art.
Image: W Dimmlich

Attempts to capture and tag some of Ascension Island’s elusive hawksbill turtles (Eretmochelys imbricata) got underway during two night dives at the Pierhead in Georgetown this week. Best known for its globally important nesting population of green turtles (Chelonia mydas), Ascension Island also has a small resident population of critically endangered hawksbill turtles about which very little is known. Hawksbills do not nest on Ascension and from their sizes it appears that most individuals are sexually immature juveniles or sub-adults, but the nesting population(s) from which they originate and the migratory pathways which bring them to the Island remain a mystery. By fitting metal flipper tags carrying a return address and taking tissue samples for mitochondrial DNA analysis we hope to answer some of these questions, as well as adding to scarce data on growth rates and residence times at Ascension. But first we have to catch them!




[caption id="attachment_393" align="alignleft" width="584"] A young hawksbill is spotted in the shallows near the pier.
Image: P v West


[caption id="attachment_394" align="alignleft" width="584"] As it swims close to the shore Dion Poncet prepares to leap.
Image: P v West


[caption id="attachment_396" align="alignleft" width="584"] Unfortunately a near miss and the turtle can be seen just escaping Dion's outstretched hand.
Image: P v West


Every evening, as many as 5-6 hawksbill turtles gather around Georgetown Pier where artificial lighting and fish discards allow them to continue foraging late into the night, making this the perfect place to start our tagging campaign. After an unsuccessful attempt earlier in the week, a crack team of elite military divers including Simon Browning, Simon Plummer and Phil Thomas managed to capture one of the largest hawksbills yet seen on Ascension - too large unfortunately, as it proved too heavy to land in the conditions at the Pierhead! Nevertheless, spurred on by their progress so far the team are planning a return visit this week and we will post an update soon.

[caption id="attachment_397" align="aligncenter" width="584"] Success! It takes Phil and two Simons to finally capture a hawksbill and shepherd it back to the pier.
Image: P v West


Contributed by Sam & Nicola Weber
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Guest — Alexander Gaos
This is fantastic stuff! Saludos from those of use working here on the Eastern Pacific Hawksbill Initiative...please let us know i... Read More
Friday, 31 August 2012 12:12 AM
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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 Island octopus

Nothing vulgar about Octopus vulgaris!


The common octopus (Octopus vulgaris) received its unprepossessing name because it is supposedly common everywhere. It occurs in every ocean where the water is warm enough for exploration by wetsuited divers. The vulgar octopus hates cold waters and established itself worldwide between latitudes 50 of both North and South. However, the well established point of view that this species is a cosmopolitan citizen began to be shaken because, one by one, different populations were found to be different species.


The common octopus from Ascension Island was already supposed to be a distinct creature, and was once upon a time described as Octopus occidentalis. However, later on this name was considered to be a junior synonym of Octopus vulgaris though it is still likely to be a new species. The Ascension octopus could be thought of as underscribed … or more precisely, under-described.




[caption id="attachment_337" align="aligncenter" width="584"] The octopus resident in his den during the day. Nicknamed "Roger" by the team, we'll be visiting regularly to see what scraps he leaves outside.

Virtually nothing is known about the biology of this octopus, and because of this when Dr Jude Brown discovered a den during one of her dives surveys, we decided to have a closer look at the behaviour of this animal, and to include repeated return visits to the den when possible. Whenever we arrived at its shelter at each day we would find the creature sitting inside and watching us with its wise and wrinkled eyes of an elderly gentleman.


The den itself consisted of a few random volcanic pebbles scattered around and was a perfect disguise for a predatory ambusher. Leftovers of the day’s food betrayed the fact that this soft bodied animal used to leave its den at night, invisible to predators. With many hungry fish lurking around any camouflage would be useful.


During the first week of observation its daily prey consisted of one to three bivalve molluscs Americardia media, sometimes spiced by some meaty cowrie  Luria lurida. No fish, no crustaceans. Our octopus appears to have a very particular diet but we shall see whether it will change its food preferences during the forthcoming two weeks.


- Post supplied by Dr Vladimir Laptikhovsky.

Recent comment in this post
Guest — Hugo Costa
I guys,Check octopus vulgaris page at http://skaphandrus.com/en/marine_species/info/species/Octopus_vulgaris, a comprehensive cat... Read More
Monday, 21 January 2013 5:05 PM
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Ascension 25/08/12

Simon Morley joins the team as a scientific diver but is also running two projects that will add to research being conducted across the globe. Over the last 10 years the team at the British Antarctic Survey have measured the temperature limits of animals from Arctic, temperate, tropical and Antarctic shallow seas. By measuring how the temperature limits of marine animals change when temperature is raised at different rates they aim to predict how vulnerable these animals will be to climate change in different locations. Ascension Island provides an ideal comparison with tropical Singapore as it compares an isolated tropical Island (Ascension) with one that is almost continuous with other land masses and is exposed to much higher levels of human influence.




[caption id="attachment_331" align="aligncenter" width="584"] Dr Morley tending to his aquaria which have been set up in the Ascension Island Conservation offices.

The second project is to look at the settlement of larvae onto an artificial sea bed that can be turned over and photographed on a regular basis. Whilst the team can deploy the plates during the survey, this project will be continued by local divers who will visit the plates every 6-8 weeks to take more photos as animals settle and start to grow on the plates. We will also attach temperature loggers to the plates so that we can measure changes in temperature throughout the year.

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Dave John Hunting seaweeds around Ascension
31 August 2013
Great to see underwater photos of this very unusual submarine environment where the ubiquitous black...
Helen Marsh Team Member Stedson Stroud
03 July 2013
Great to hear more about Stedsons work, and how he got started, having met him on Ascension Island l...
Simon Plummer Volunteer Ecological Surveyors
10 June 2013
I can’t stop smiling thinking of what a brilliant time you are having. The fact that I can visualise...
Simon Plummer Black triggerfish anecdotes
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An enjoyable and funny read, thank you steve for making me chuckle.
Simon Plummer Ascension Island fish record
10 June 2013
The photos are brilliant, envious.

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