Expedition blogs and news from the Shallow Marine Surveys Group

Ascension Fireworms

Amphinomid polychaetes are commonly known as fireworms due to the burning sensation once their chaetae (fine 'hairs') break after penetrating our skin; however specimens belonging to only a few genera produces the stinging sensation. They are brightly coloured and can reach quite a large size, up to 50 cm long. Fireworms thrive in intertidal zones and can be abundant in coral reefs or rocky areas, although there are some deep-water genera.

During the dive surveys of Ascension Island the SMSG team found two species of fireworms which have now been identified by Beatriz Yáñez Rivera, of the Universidad Nacional Autónoma de México, as  Hermodice carunculata and Eurythoe complanata.

Hermodice carunculata

The first fireworm recorded from Ascension Island was collected in the middle 1800s. This fireworm is Hermodice carunculata, however at the time it was considered to be another species due to great morphological variation. Now, genetic evaluation indicates that Hermodice carunculata have a broad distribution across the Atlantic Ocean. This species shows ecological adaptations according to habitat conditions and different colouration with low genetic divergence. The population from Ascension Island could be playing an important role in the connectivity between both sides of the Atlantic Ocean.

[caption id="attachment_760" align="aligncenter" width="584"]Hermodice carunculata Hermodice carunculata

Eurythoe complanata

The discovery of Eurythoe complanata represents the first record from Ascension Island. This species has been reported in mainland and some islands of the Atlantic Ocean. These fireworms are common in shallow waters mainly in rocky shores, and they reproduce sexually and asexually. Sexual reproduction involves a rostraria larvae, which has been hypothesized to enable the long-distance dispersal of this species of fireworm.

[caption id="attachment_754" align="aligncenter" width="584"]Eurythoe complanata Eurythoe complanata

- Text by Beatriz Yáñez Rivera

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Survival against the odds by a small, isolated population of Ascension corals

The brooding reef coral Favia gravida (Verrill 1868) is found on the mid-Atlantic volcanic islands of Ascension and St. Helena, about 1,300 km apart.

First recorded in 1881 in small tidal rock pools, Professor Wirtz revisited the original site at Shelly Beach, Ascension Island, during the recent SMSG expedition.

[caption id="attachment_742" align="aligncenter" width="584"]Peter Wirtz collecting samples from the Shelly Beach rockpools. Peter Wirtz collecting samples from the Shelly Beach rock pools.

Although a large number of dead corals were found in the pools, the small population has somehow persisted to the present day. In a new publication, authors Bert Hoeksema and Peter Wirtz suggest that the remarkable survival of Ascension’s small population for at least 130 years has been made possible through inbreeding and fragmentation, suiting it for life on the bottom of these unique shallow rock pools. The full article can be found and downloaded here.

[caption id="attachment_741" align="aligncenter" width="584"]Live corals photographed in situ Live corals photographed in situ

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Morays of Ascension

One of the most common sights for any diver at Ascension Island is the moray eel. It seems that almost every suitable crack, crevasse, fissure, or small cave is inhabited by one or more of these sometimes rather large animals. While generally harmless if undisturbed, it pays to check before kneeling or grasping any handholds as a needle-toothed moray is never very far away!

This gallery presents all the species recorded by our cameras during the 2012 survey.

[gallery orderby="title"]
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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)

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