Iceland’s Shallow Hydrothermal VentsLatest update June 21, 2019 Started on December 2, 2018
We are planning an expedition to explore the marine animals living near Iceland’s shallow hydrothermal vents, and the adaptations they may be making to these seemingly hostile yet very productive environments.
We started another glorious fieldwork day with a trip to the main Strytan vent chimney, taking both ROV Thomas and ROV REX with us to document the chimney from base to tip. Unfortunately due to a fault with the rear propellors of ROV Thomas, we were not able to use him in the end, and therefore had to deploy just ROV REX instead. There was a bit of current at the surface but below the waves, visibility was great and with Adrian piloting, we found the tip of the main chimney and proceeded to follow it down to its base. Eventually, we touched down on a sandy bottom littered with shell fragments, quite a different habitat to the walls of the vent chimney. Then following the vent chimney up, we encountered chimney surfaces without vent fluid flow, covered in encrusting, filter-feeding marine invertebrates such as sponges and bryozoans. The bryozoans were densely intertwined with other fauna, forming a fuzzy, grass-like covering referred to as turf.
As we ascended further, in many places we observed the feeding tentacles of terrebellid polychaetes, which form a spaghetti-like covering on the turf. Also prominent were beautiful Metridium anemones with intricately branched tentacles, which were especially abundant near the tops of some extinct chimneys adjacent to Strytan. Most of the active vent fluid flow on Strytan can be found in its upper half, where the surface of the chimney is visibly whiter due to freshly-deposited minerals. Near to these areas, we observed more bryozoans, mussels, as well as hydroids, which are tiny branching cnidarians with tentacles emerging from small cups.
Meanwhile, Cris was diving at a dive site we referred to as 'the other wall' to collect more faunal samples to compare with those we found at the vent chimney. There were plenty of samples to process in the afternoon, therefore a few of us got on with this while Cris did his first SCUBA dive on the main Strytan vent chimney.
Our #LifeFromVents dives (both ROV & SCUBA) are now complete, so today we're making sure all the data and samples are in order, and starting to pack up the lab and equipment.— REX (@rov_REX) June 18, 2019
Meanwhile, the vents in the fjord keep on venting, as they have for the past ~10,000 years... pic.twitter.com/SUnFrxiEu6
Today was the beginning of our sampling operation - we are using divers to collect samples of marine invertebrates from the vent chimneys. Our diving team comprised Cris Little from the University of Leeds, who has lots of experience of diving in the chilly waters around the UK, and Erlendur Bogason, owner of Strytan dive center and also official protector of the Eyjafjörður vents, which were designated as the first protected marine area in Iceland.
The divers are targeting specific animals for our project, for example mussels, which occur both on the vent chimneys near the hot fluids but can also be found away from the chimneys. Having examples of the same species from both near the vent chimneys and away from them will allow us to compare their genetic material, and determine if the specimens collected the vents are demonstrating any signs of adaptation to this environment.
We kitted Cris and Erlendur up with a lot of gear for the sampling - a goody bag consisting of plastic jars ready for samples, a slate to record important notes on each collected specimen, a temperature sensor to take note of the temperatures that collected specimens were exposed to, a camera to record footage of the collection, and line to measure distance from the vent chimneys...and this was all in addition to the myriad of equipment that is needed for diving. Despite the awkwardness of handling all this equipment while underwater, Cris and Erlendur did very well to collect multiple specimens of our target taxa, and much of the rest of the day was spent in the lab processing these.
We have been very lucky that Iceland greeted us with beautiful weather. During the first work day of our stay here, we started off with set up of our lab space, located inside Strytan Dive Center, which is located within an old herring factory on the edge of the fjord. On the top floor of the dive shop there is a small museum, exhibiting fragments of the vent chimneys that we are going to be exploring. It was great to have a look at them up close, and examine them for signs of the marine animals that lived on them.
After acquiring a boat and skipper, and additional set up of mini ROV REX (a companion to ROV Thomas - a small ROV jointly owned and operated by the Natural History Museum and University of Southampton), we set off for our first glimpse of the main Strytan vent chimney. It was absolutely incredible dive - we navigated around the chimney exploring its shape, fauna, and the places on it where hot fluids were escaping, which appeared as a mesmerising shimmer above white freshly-deposited parts of the vent. Buzzing from this, we set off back to the herring factory and ran into curious humpback whales. That really topped off an amazing day!
Carrying a lot of gear, we finally arrived in Iceland today for our fieldwork to explore the shallow hydrothermal vents that can be found to the north of the island. Iceland greeted us with wonderful sunny weather and a fresh gentle breeze, and soon after we began our 5 or so hour drive from Reykjavik to Akureyri. We passed stunning scenery along the way, and feel very lucky to have ended up at a beautiful spot overlooking Eyjafjörður. It is now nearly midnight, and despite it still being sunny outside, and our team is retiring for some much needed rest ahead of underwater explorations tomorrow. Fingers crossed that the good weather holds!
Nearly fieldwork time!
It is now just over one week to go before our field expedition to explore Iceland’s shallow vents, and our trident ROV Thomas is safely packed for his trip. We have ended up with quite a lot of cases for a one week visit…but who knows when a sieve might come in handy!
In light of how soon our trip is, I thought it might be useful to recap the aim of our project, which is to explore how the animals living on and around Iceland’s shallow vent chimneys might be adapting to the conditions presented by the vents. We are interested in how hydrothermal vent environments shape the evolution of animals in general, and exploring Iceland’s vents will allow us to see if even animals from shallow-water marine communities are actively adapting to the harsh conditions of vents (high and unstable temperatures, toxic chemicals) to reap the benefits of living near a vent (greater food availability as a result of chemosynthetic production). As we will be assessing whether a shallow Arctic marine community is potentially adapting to greater and/or more unstable temperatures, we hope that our results will also tell us how such communities will fare in light of climate change.
Also included in this post is some more video from ROV Thomas' test outing in Southampton, which reveals wonderful tubeworms, anemones, and sea squirts on the dock wall.
This week, we were able to take our trident ROV on its first ever dives, to test it and get used to handling it ahead of our visit to Iceland.
We deployed it within the docks at the National Oceanography Centre, Southampton (NOCS), from the R.V. Callista. This ship is skippered by Bill, and both him his awesome pet labrador Thomas have been on many exploration adventures with us so far, so we decided to name our trident ROV Thomas in honour of Thomas the dog.
Testing went very well, and we were very impressed with the quick and easy set up of ROV Thomas, as well as the video quality. We definitely need to get better at handling it, but despite this ROV Thomas was able to reveal to us the nature of the NOCS dock seafloor, as well as the many marine invertebrates living on the dock wall.
What lives on Iceland's vent chimneys?
Time is drawing closer to our adventure, with only a month and a half to go before we visit Iceland’s shallow vent chimneys! At this stage I thought it might be good to explore what creatures we might expect to find living on them.
In Icelandic marine waters in general the fauna is made up of arctic-boreal and boreal species which can also occur in western European waters, and there are also some American species. Around 3.6 million years ago when the isthmus of Panama formed and closed the Central American Seaway, the flow of Pacific water from the Bering Strait and Arctic Ocean into the Atlantic brought a range of Pacific marine invertebrates to Iceland, including the blue mussel (Mytilus edulis) and the common whelk (Buccinum undatum).
There has been little work to document in detail specifically the animals living on Iceland’s shallow vent chimneys, but the many divers that have explored the site have provided valuable indications in the form of pictures and videos of what lives there. The chimneys appear to be dominated by algae and benthic invertebrates that occur on the sides of the chimney cones, sometimes living very close to the conduits from which the vent fluid escapes. Anemones, bryzoans and sponges appear to be abundant encrusting fauna on the vent chimney walls, with molluscs such as mussels and gastropods occurring around these. Sea urchins and seastars are also often observed on the vent chimneys.
The microbial life of Iceland’s vent chimneys has been researched in relatively more detail, with studies of shallow vent chimneys spewing alkaline fluids typically having microbial communities dominated by heterotrophic and mixotrophic Gammaproteobacteria and/or members of the Firmicutes phylum. The community of microbes found at Strytan appears to include over 50 strains of thermophilic microbes, with bacteria mainly from the Aquificales group and Archaea mainly from the Korarchaeota. These microbes appear to reflect the freshwater inputs into the Icelandic vent chimney habitat.
More on Iceland’s vent chimneys
In the deep ocean, the chemistry of hydrothermal vent environments can have a big influence on the communities of life that form at these sites. A lot of vent chimneys in the deep sea are comprised of iron sulphide minerals such as pyrite, and spew a fluid that is rich in hydrogen sulphide. This gas is used by certain types of microbes (sulphide oxidisers) to convert carbon dioxide into food. In the absence of light, these microbes can dominate deep sea vent communities and would feed the range of highly specialised animals that have made their homes there.
Iceland’s vent chimneys are somewhat different to those commonly found in the deep sea along mid-ocean ridges. Rather than iron sulphides, the Icelandic vent chimneys are comprised of saponite, a clay-like mineral which is rich in magnesium, silicon and aluminium, and the fluid that emanates from the Icelandic vent chimneys is also unlike that which flows from deep sea vents, because it is derived from rainwater, whereas the fluid flowing out of deep sea vents is modified seawater. Iceland vent chimney fluid is also alkaline, has a low mineral content, and has a temperature of around 80°C. It is thought that the chimneys have been around since the last ice age, and are 11,000 years old, while the fluid flowing from them is over 1,000 years old!
The organisms that are found on the Icelandic chimneys are also somewhat different to those at deep-sea vents - because Strýtur and Arnarnesstrýtur occur within shallow waters easily reached by light from the sun, the communities are more typical of shallow-water arctic marine environments, which are typically supported by photosynthesis rather than the chemicals coming out of the vents.
The Trident ROV is here!
We are absolutely thrilled to have received support for our project from the S.E.E. Initiative, and very grateful for their donation of a Trident ROV to help us explore!
The Trident ROV arrived safely this week in our lab at the Natural History Museum in London, and I have been attempting set up as well as trying to figure out the controls, so far it all seems fairly straightforward.
For now the Trident has been having a quick explore of our shelves of intriguing specimens brought back from various ocean expeditions, but very soon we are planning to take it on its maiden voyage. Suggestions of nearby waterbodies for this include the Serpentine lake in nearby Hyde Park and the Regents Canal, the labteam and I are very excited to put it in the water!
Iceland and its hydrothermal vents
I often hear from people who have been to Iceland that is a very odd and interesting place, with an arctic landscape that you might expect from another world altogether. This is probably due to its fairly unusual geological situation - Iceland formed around 60 million years ago as Greenland was drifting away from Scotland, due to the presence of a hotspot in the middle of the expanding Atlantic Ocean. Essentially the Mid-Atlantic Ridge runs right through Iceland, and this is responsible for making Iceland a very volcanically active place - volcano eruptions are fairly frequent on the island, as are geysers and land-based hot springs. Iceland itself is growing at a rate of 20 km per million years, and its geothermal potential is also harnessed for energy as well as food production. I was intrigued to find out that on Iceland, tomatoes are grown in large geothermally-heated greenhouses!
As Iceland is essentially a surface expression of the Mid-Atlantic Ridge, this creates the possibility for hydrothermal vents to exist at much shallower depths than they are normally found. The story goes that hundreds of years ago fishermen measuring the depth of Iceland’s northern fjord Eyjafjörður discovered hydrothermal vent chimneys there, that rise from depths of 65 m to only 15 m from the sea surface. These vents, known as the Strýtur vent chimneys, were more recently rediscovered by divers, and similar vent chimneys were also found at another nearby site in Eyjafjörður, known as Arnarnesstrýtur. As the tops of these chimneys reach depths of 15-20 m, they can readily be explored through SCUBA diving, and therefore much more easily than vents in the deep sea.
What is a hydrothermal vent?
Our ocean contains many amazing and distinct habitats, and hydrothermal vents are amongst the most remarkable.
Hydrothermal vents are essentially hot springs, but ones that occur within the ocean and most commonly in the deep sea, typically at depths of around 2500 m and in environments such as mid-ocean ridges. They form wherever there is sufficient heat and porosity to drive the convective flow of seawater. At mid-ocean ridges, stretching of the oceanic crust causes it to crack, allowing seawater to penetrate deep into the Earth's crust. On its journey towards the mantle, this water is heated, picks up dissolved minerals and gases, and is circulated back to the seabed where it erupts as a hydrothermal vent.
The water that emanates from hydrothermal vents can be over 400 °C! But it mixes quite readily with surrounding cooler seawater to create more ambient conditions in which animals can thrive.
Animals are also drawn to hydrothermal vents in the deep sea because they are incredibly productive environments compared to much of the deep ocean. The gases entrained in vent fluid can be used by microbes to fix carbon dioxide, thereby converting it to food in a process similar to photosynthesis but that occurs completely in the dark.
Because of their high productivity, animals (typically marine invertebrates) are often found at vents in incredible abundances. And the animals that thrive there are often different to those found within other deep sea habitats as they have novel adaptations to survive at vents, such as very close-knit associations with microbes that ensures a regular supply of food, and ways to cope with the heat and toxicity of the vents.
Deep-sea hydrothermal vents (or marine hot springs) are home to extraordinary, highly-specialised marine animals, adapted in a variety of ways to obtaining their energy from the chemicals emanating from these vents. While the sharp temperature gradients, unstable, and toxic conditions typical of hydrothermal vents can make them challenging habitats for marine life, the ready food supply provides a strong incentive for adapting to vents. Over Earth’s history, a wide variety of animal types have colonised hydrothermal vents, and vent environments therefore appear to be important for driving the development of novel adaptations in animals in the deep sea, but the mechanisms through which vent adaptation happens are largely unknown. Uncovering how animals adapt to vent conditions can give us crucial clues for predicting how marine life may respond to major environmental challenges such as climate change and pollution. The majority of Earth’s hydrothermal vents are fairly difficult to access as they are found at over 2 km water depth, however, off the northern coast of Iceland hydrothermal vents occur at a depth of just 15-70 metres. In this project we are planning fieldwork to explore what animals living near Iceland’s shallow vents, and the adaptations they may have made to the vents using genetic tools.
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