IPY Census of Antarctic Marine Life
Census of Antarctic Marine Life Diary 2008
By Jan Strugnell
Biologist Jan Stugnell is onboard the British Antarctic Survey’s research ship RRS James Clark Ross in the Bellingshausen and Amundsen Seas, Antarctica. Scientists onboard are studying tiny marine creatures from the ocean shelves and slopes from this little-known region. Their investigations will help determine the biodiversity of this extreme environment and provide clues to evolution and past history of climate, geology and oceanography. The research cruise is a key part of a international interdisciplinary studies including the International Polar Year’s Census of Antarctic Marine Life (CAML) and the Antarctic benthic deep-sea biodiversity (ANDEEP).
In her diaries Jan describes what it’s like to be part of a research team.
18-20 February Boarding the James Clark Ross!
Today we all joined the RRS James Clark Ross (JCR) at Port Stanley, Falkland Islands, to get ready for our cruise! The JCR is almost 100m long and seems enormous when it is docked at Stanley. The hull is painted bright red and the words ‘James Clark Ross’ are written in large white letters at the front.
The JCR was named after Admiral Sir James Clark Ross, R.N. (1800-1862) who discovered the North Magnetic Pole in 1831. During 1840-43 he also made three voyages to Antarctica in an attempt to reach the South Magnetic Pole, and to undertake a range of scientific studies of the region.
The JCR can hold 80 people, and for our cruise we have 24 scientists and 28 crew onboard. We are heading to the Amundsen and Bellingshausen Seas for 50 days for geological and biological sampling.
The scientists for this cruise, known as JR 179, comprise 11 geologists and 9 biologists. The geologists are mainly interested in sampling the sea floor for evidence of past glacial features and past climate change (but more on this later) and are supported by the BAS core projects PEP-G and QWAD. The biology team (of which I am a part) is focusing on benthic (bottom) sampling and also epi-benthic (just above the bottom) sampling to obtain of idea of the marine life which lives on and above the sea floor. This work is part of the BAS core project BIOPEARL and is supporting the Census of Antarctic Marine Life (CAML) IPY project by having me (Jan Strugnell) and Stefanie Kaiser on board.
We spent the day being very busy unpacking all our kit and assembling trawls and bits and pieces in preparation for the cruise. It's much easier to do this while the ship is steady and in port and so we are trying to do as much in advance as we can. Everything has to be tied down and safely secured before we leave to stop it being thrown around when we are at sea.
The weather has been spectacular in Stanley and many people have even got sunburnt!
22 February 2008
Today we set sail for Antarctica at 5pm. Everyone was very excited to finally get going and we all climbed up on the monkey deck as we sailed out from Stanley and started to cross the Drake Passage. There were some seals playing in the water and they were as interested in us as we were in them!
It is pretty windy (about 35 knots) and so the ship is rocking a bit, but not too badly. I've managed to avoid seasickness, but have been quite sleepy (a symptom of sea sickness) and so have been sleeping very well despite the rocking.
Today we have been getting ready for trawling, which will start in a few days time. Everyone is pretty excited to see what we will catch as very little trawling has been done in this area and there will almost certainly be some species new to science!
24 February 2008
We have now nearly made it through the Drake passage (the tip between South America and Antarctica). The conditions have been really quite rough for the last few days (typical for the Drake passage) with winds over 40 knots! This has made for quite a bumpy ride and a few people on board have suffered from sea sickness – thankfully I have not been one of them!
Today we have done our first bit of science! This took the form of deploying a CTD. This stands for conductivity (this is a proxy for salinity), temperature and depth, and these are some of the parameters that the instrument measures. It can also measure oxygen concentration, current speed, fluorescence and a range of other parameters. The CTD is deployed over the side and lowered to the bottom. It can measure each of these parameters from the waters surface all the way to the bottom and this enables the scientists to build up a picture of the water masses around Antarctica. The CTD also can sample water at specified depths throughout the water column. The microbiologists (part of BAS’s long term monitoring programme) are collecting these water samples to study the composition of bacteria in the water column, and specifically to compare the bacterial diversity at our current position (which is a relatively long way away from land) to regions which are closer to land, and potentially subject to run off.
It was exciting to finally get our science part of the cruise underway. Now we are on our way to the next station!
26 February 2008
This evening the geologists did their first bit of coring of the seabed as part of BAS’s QWAD (Quaternary Western Antarctic Glaciation) project.
To determine the consistency of the sea floor they send sound waves from the ship to the seafloor using a piece of kit called TOPAS. The sound waves bounce back to the ship where they are received. Some of these sound waves penetrate the sediment and allow a profile to be built up of the sea floor. This allows the geologists to find areas where there is good sediment to sample. If they tried to sample a rocky bottom for example, this would damage the very expensive coring equipment!
They used a piston corer to sample the sediment. They were targeting a sediment drift in which they hope carbonates are preserved. This was in 2300 m of water and they managed to obtain a 10 m long core. Carbonates are critical for isotopic work but unfortunately they are very rare in the Southern ocean. The geologists are hoping that they were able to obtain some carbonates and then they will use these in isotopic studies to build up a picture of past climates (palaeoclimates) and ocean circulation patterns.
27-28 February 2008
Today was an exciting day for the biologists as we had our first day of trawling in the Bellingshausen Sea as part of the BAS core BIOPEARL project. We deployed the Agassiz trawl to sample the benthic marine communities and did 2 x 15 minute trawls at 1500 m depth, 3 x 15 minute trawls at 1000 m depth and 3 x 10 minute trawls at 500 m depth.
The spirit of international collaboration does not just extend to the variety of different nations' scientists on board, but no sooner than a tiny sea spider had been caught, was it photographed and sent to an expert taxonomist in Spain who was then able to confirm its identity to species level back to the ship in the same day. Meanwhile new photos of benthic species had already been sent to experts in Chile, Germany, Russia and home to the UK.
We were lucky to catch some really interesting animals! Of particular interest includes:
an acorn barnacle (Verruca cf. gibbosa) from 1500 m. This is only the 4th record of acorn barnacles from the Antarctic. This find is of particular interest for the BIOPEARL team as they are currently working on the molecular species relationships of Antarctic barnacles.
An Antarctic deep-sea shrimp (Nematocarcinus lanceopes) from 1500 m. Specimens of these have been seen in more than 4000 m depth on video images from the Weddell Sea. Before spawning, the females swim up through the water column and release the eggs. The young crustacean larvae can be found in surface waters where they feed on phytoplankton.
Buccinid gastropods (from 1000 m). Species of the family Buccinidae are scavenging and predatory snails that can drill holes into their prey.
An unusual fish with a worm-like lure from its bottom lip (caught from 500m). Presumably the fish uses this lure to attract prey close to it.
As well as catching animals, every Agassiz trawl apart from one also managed to
capture a number of large rocks. Although these rocks can rip holes in the net, they also contain many tiny encrusting animals. Sometimes the total biodiversity of an entire catch is dominated by these cryptic species. Even just from this first site we have found a new species to science and one that may even be a new genus. Another we have recorded a new southern-most range limit for and yet another at its deepest depth ever reported, these details are important as they may be crucial in showing us how ecologically flexible such species are and so how well they may cope with man-induced changes that are sweeping the planet.
3 March 2008
We were incredibly lucky today to have a pod of Minke Whales accompany the ship as we made our way through the ice into the Amundsen Sea, on our approach to Pine Island Bay!
Around 10 whales spent a few hours at the bow of the ship to the delight of the scientists and crew who were huddled at the bow together in the cold watching them. Some of the scientists and crew who have spent a lot of their working lives at sea said that they had never seen whales so close before! We were so incredibly close to the whales that as they came to the surface for air we could hear them breathe and even smell their fishy breath at times!
The whales really seemed to perform for the many cameras that we pointed at them, and would flip upside down underwater and swim belly up. A few of the whales came up far enough out of the water to look back at us.
Saturday 8 March Trip to Unnamed Island - it’s all about the poo
This diary entry is from Dr James Smith, a geologist on board, who was one of a small party that were lucky enough to go on an excursion to a small island within Pine Island Bay for geological sampling. They were also lucky enough to see moulting Adelie Penguins and Elephant Seals on the Island!
The purpose of our visit to ‘Unnamed Island’ was to follow up to a trip made by one of our colleagues at BAS, Dr. Jo Johnson who visited the island in 2006. Jo, then on the German research ship RV Polarstern, was busy collecting rock samples from around Pine Island Bay to date the thinning history of the West Antarctic Ice Sheet since its last glacial maximum (about 18,000 years ago). This work forms part of the GRADES-QWAD programme at BAS, which involves geologists, glaciologists and oceanographers. The rock samples Jo collected from Unnamed Island have been used to date the emergence of the island from the sea or from beneath the expanded ice sheet several thousand years ago. Jo used a method called cosmogenic dating to date the rocks. This technique measures the amount cosmogenic radiation the rock has been subject to since it was first exposed to atmosphere (known as its exposure age). The purpose of our visit was to look for other types of material to date in order to verify Jo’s data. We knew from Jo’s account of the island that it’s covered, quite literally, in a layer of guano or penguin poo. Fortunately for us we can date penguin poo very accurately using radiocarbon dating so in theory, if we could find a thick enough sequence of poo, it could tell us when the island was first colonised by penguins and therefore provide us with a minimum age for when the island emerged from beneath the sea or the ice sheet. After a quick look around the island we found a suitable mound of poo to sample. We first scraped away the surface poo with a spade and took a series of samples from the base up to the surface. For the record, penguin guano has a very distinctive and rather unpleasant smell that was, unfortunately for us, quickly transferred to our clothing, hands and equipment! We hope the new dates from Unnamed Island are worth it!
Pine Island Bay, Amundsen Sea
We have been incredibly lucky that the ice conditions have allowed us to enter Pine Island Bay, (in the Amundsen Sea) to carry out the BIOPEARL sampling programme as planned. In many previous years, Pine Island Bay has been inaccessible, due to a thick ice sheet, and so we are very fortunate that it is open at this time.
Literally nothing is known of the benthic fauna of the Amundsen sea, south of latitude 66° south, because no one has sampled here previously. Therefore anything we find here is a new record of a species in this area!
We have had a very busy few days (and nights!) on board completing our sampling protocol. We sampled replicates at 1500 m, 1000 m and 500 m depth using both the Agassiz trawl, which samples the life on the sea floor, and the Epibenthic sledge, which samples life just above the sea floor. We also took a CTD (conductivity, temperature and depth) at each site, to build up a profile of water parameters at these depths and also to collect bacteria from the water column. We also used a box corer to sample the top 30 cm or so of the sea floor to be able to sample the burrowing animals which live within the it.
Without a doubt the sea floor of the region of Pine Island Bay where we have been sampling is incredibly muddy. The mud is made up of incredibly fine grained particles and the mud itself is incredibly gooey and it sticks to all the animals within the catch (and us too!). After every trawl we have had to sieve the catch and wash it down with sea water to liberate the animals from the huge volumes of mud. This has been a very labour intensive task, but everyone has helped out and has got very muddy in the process!
So far we have seen representatives of most of the major groups of animals known from Antarctic waters; including various kinds of fish, (many with strange adaptations such as long spines to hold them above the muddy sea floor), large sponges (sometimes up to 0.5 m in length!) molluscs (we have had representatives of octopus, bivalves, snails, tusk shells and chitons), echinoderms (sea urchins, sea cucumbers, brittle stars and star fish), crustaceans (isopods, amphipods, krill and other prawn like animals), corals, bryozoans and various kinds of worm-like creatures (including polychaetes, nematodes, nemertean worms, sipunculids and echiurans).
Everything we catch is carefully photographed as quickly as possible to aid in later identification. Tissue samples are then taken for DNA and RNA analysis and some DNA extractions are performed immediately on board. All the animals we catch are preserved and are brought back to the UK for identification and further analysis.
The catches from 500 m depth tend to have a lot higher numbers and diversity of animals than those from the deeper depths. We are now about to begin our second set of sampling within Pine Island Bay at 500m and although we are all quite tired, we are pretty excited to see what the next catch will bring!
11 March 2008 Octopus of Pine Island Bay!
I am a molecular phylogeneticist at Cambridge University (funded by a Lloyd’s Tercentenary Foundation Fellowship) and I am investigating the molecular evolutionary history of Antarctic and deep sea octopus. I am therefore on board to sample any octopus we catch in our trawls for later DNA sequencing and also to preserve them for later investigation and identification.
Specifically I am using octopus as model organisms to test the hypothesis that the Antarctic has acted as a centre for evolutionary innovation and radiation and as a source of taxa that have invaded the deep sea. I am also interested in investigating how past glaciation in Antarctica has effected octopus speciation, and also at the effect of the Antarctic Circumpolar Current on octopus dispersal and population genetics.
As with all other groups of animals, nothing at all is known of the octopus fauna in the Amundsen Sea as no one has sampled here previously. Therefore any octopus we catch from this region is a new record of life in the Amundsen sea! Despite the fact there are three genera (Adelieledone, Pareledone and Megaleledone) (and upwards of 20 species) of octopus which are known to be endemic to, and only found in, other regions of the Southern Ocean, I must admit that I was initially quite nervous that we would not catch any octopus! Thankfully my fears were unfounded and so far we have managed to catch a range of really interesting octopuses in the Amundsen sea.
We have caught 2 cirrate octopus both from 500 m and 1000 m depth. These are the "dumbo" type octopus which have large fins on either side of the mantle and they undulate these for propulsion through the water column.
We also caught an individual of Megaleledone setebos from 500m depth. This is by far the largest octopodid in the Antarctic, with a total length known of almost 1 metre! This individual created lots of interest from everyone on board when it was caught as it is by far the largest animal we have caught so far! This species is known to be of some ecological importance in the Southern Ocean as beaks of this species have been found in the stomach contents of Elephant Seals and Weddell Seals.
We have caught a number of individuals belonging to the genus Pareledone from 500m depth. Eight new species of Pareledone have been described in the last few years and it is highly likely that some of the individuals caught from this region will be species new to science!
14-15 March 2008 Sea Mount trawling
Tonight we did some trawling on one of the Marie Byrd sea mounts in an attempt to sample some corals for the geologists on board. The geologists were hoping to collect some corals to look at past carbon dioxide levels held within the coral structure. Deep sea corals had been previously discovered in the Amundsen sea region and initial analyses of them showed that some of them were alive during the last ice age! (between 12,000-24,000 years ago).
During the last ice age the concentration of carbon dioxide in the Earth’s atmosphere was about 1/3 lower than at the start of the present warm period. Climate researchers do not know the location of the “sink” for the carbon dioxide during this time. One explanation is that this carbon dioxide, which is in continuous exchange with the surface waters of the world’s oceans, was locked up as dissolved carbon dioxide in the deep Southern Ocean during the last ice age. Therefore, deep sea corals represent a unique opportunity for investigating if the deep Southern Ocean was the world’s carbon dioxide sink during the last ice age.
The biologists were also interested in any other fauna that we could collect from there as very little is known about sea mount biology and so anything we would collect would be of interest.
Trawling in potentially rocky conditions at depth is greatly increases the risk of getting the trawl stuck, damaging the trawl or even possibly losing it on the bottom! We were therefore a little worried about the condition that the trawl would come back in, if it would come back at all!
Firstly we trawled at 3000m water depth to sample the side of the sea mount. It took over an hour for the trawl to just reach the bottom at this depth and then another hour to be bought back up! The trawl came back in good condition, but unfortunately we did not manage to collect any corals for the geologists and in fact the catch was quite small; we caught brittlestars, an isopod and seacucumbers.
We then decided to trawl across the top of the sea mount at a depth of 2200m to sample the fauna there, and again, hope to collect some corals for the geologists work. Again the catch was very small, and this time contained a serolid isopod, a soft coral and an armoured seacucumber.
This is interesting because it is the first time that the biology of any Amundsen Sea seamounts have been sampled. Upon first inspection the animals seem very similar to those we found living at similar depths on the continental slope off Pine Island Bay.
22 March 2008
The last few days we have been searching for suitable coring sites and coring for the geologists for the BAS CACHE-PEP-G program. This focus of this program is to investigate the last 10, 000 years of Earth history and specifically how the Antarctic climate has interacted with the global climate. The program uses ice cores, lake sediments and marine sediments to build up this picture.
On this cruise, the geologists are trying to find marine sediments that have built up over the last 10,000 years. Marine sediments are built up over time from tiny photosynthetic algae, specifically siliceous diatoms. When these diatoms are alive they live in the surface layers of the world’s oceans. Different diatom assemblages thrive under different conditions of nutrients, temperature, light and ice conditions. When the diatoms die they sink to the sea floor and therefore this builds up a picture of past climatic conditions in the sediments. By taking a core of these sediments, the geologists are able to essentially look back through time and use the diatom assemblages as indicators of past conditions climatic changes.
To date, there are no published records of these diatom assemblages from the entire Pacific area of the Southern Ocean! Therefore the aim of this part of the cruise is to obtain some cores from this region of Antarctica to get a better idea the climatic patterns in this area over the last 10,000 years. The geologists are using a piston corer to do this, and hope to obtain a number of 10-12 metre long cores of sediment from this region.
The picture below is of a siliceous marine diatom. The presence of is indicative of sea ice whilst the presence of Chaetoceros dichaete is indicative of high productivity.
25 March - Epibenthic sledge (EBS) sorting
Although the majority of the trawling is now completed for the biologists on board, the work has not stopped! There is still plenty of activity in the laboratories and computer rooms to process all of the samples.
Steffi, Dave and Adrian have been spending a lot of time looking down their microscopes sorting the animals that were caught in the Epibenthic sledge (EBS). The animals caught in the EBS typically range in size from 7 mm to 70 cm, although it must be said that some of the largest animals we caught were also captured in the EBS, including a sea cucumber at least 50 cm long!
We are lucky that we have a number of taxonomic experts on board to sort the animals. We have experts on polychaetes (Adrian), bryozoans (Dave) and isopods (Steffi) and so much of the identification and fine level sorting can be done whilst we are on board. Katrin, the group leader (back at BAS) is also an expert mollusc taxonomist. The rest of the animals that cannot be identified are sorted into taxonomic groups and sent to experts at a later date to be identified.
The sampling design of the EBS was set up to try and determine the scales upon which biodiversity is organised in the Amundsen Sea region, as very little is understood of the patterns of abundance, dominance and richness of animals in the Southern Ocean. The EBS sampling design was organised to sample at 3 sites (including inside and outside of Pine Island Bay) with 6 replicates at 500 m at each site and 2 replicates at 1000 m and 1500 m. Both a lower and an upper net on the EBS collected at each of these sites. This comprises a total of 60 samples to be sorted through!! Box cores were also taken from each site and these will provide a measure of grain size and organic content of the sediment at each location.
Commonly there are in order of 1200 animals in a single sample and so this is quite a labour intensive task! So far the initial work on these samples reveals them to be incredibly diverse - with 13 Phyla identified in a single sample. This is an impressive and remarkable level of diversity and represents 1/3 of the major animal body plans that exist on the planet! When completed, this work will provide some strong insight into the geographic and bathymetric scale at which biodiversity is organised in this region, and is likely to turn the Amundsen sea area from perhaps the world’s least known sea, into a region in which we have the best idea of the structure of biodiversity in the Southern Ocean.
1 April 2008 Water, water all around...
Four different scientists with very different research interests have been collecting samples of seawater from the water column using the CTD. The CTD is an instrument used for measuring a number of parameters from the water column (including Conductivity/salinity, Temperature and Depth) and can also be used for collecting water samples from a number of depths throughout the water column. For this weeks diary entry I had a chat to each of them about their science.
National Oceanograpy Centre/University Southampton and BAS PhD student, Rachel Malinowska has been collecting water samples for her PhD using the CTD. Rachel is taking a depth transect from 10 depths (from as deep as 4500 m) from 6 sites around the Bellinghausen and Amundsen Seas and is looking at the differences in bacterial community structure from the sea surface to the sea floor. She has previously investigated bacterial community composition and abundance from sediments in the Southern Ocean and she is now interested in determining whether the breakdown of organic matter occurs during its fall through the water column or in the sediment of the deep sea. Rachel is also interested in comparing bacterial communities in surface water from different regions around Antarctica. She already has samples from the Scotia Arc and Kerguelen and is now adding samples from the Bellingshausen and Amundsen Sea for this biogeographical comparison.
Paul Carter is a PhD student from the Bristol Isotope Group (Bristol University, Earth Sciences Department) and is also collecting water using CTD’s but is hoping to gain very different information from the samples. Paul collects water samples to extract a trace metal called Neodymium. Neodymium originates in rocks on the land but over very long periods of time some of it washes into the oceans. It is present in tiny concentrations in the Southern Ocean (around 20-30 picomoles per kilogram!), but even at this small concentration it is a useful water mass trace and can be used to help determine the movement of water masses around Antarctica and the world’s oceans. Paul collects water at 500 m depth intervals throughout the water column to just above the sea floor. Due to the very tiny concentrations of Neodymium present in the Southern Ocean, Paul needs to filter 4 litres of water for a single sample. He will analyse the water samples for their Neodymium concentration using Mass Spectrometry back in Bristol. Paul’s work is the first study to look at Neodymium concentrations in Antarctic waters.
Dr David Pearce is a microbiologist at BAS and works for the Long Term Monitoring Programme (LTMS B task 7). David is also collecting water from the CTD for a microbial metagenomics project. Microbes include those organisms which are not visible to the naked eye. David is interested in extracting and sequencing the entire microbial DNA present in the water samples he collects to obtain a picture of the ‘whole environmental genome’ from his samples. He is hoping to use this to build up a picture of the physiological potential of these microbes. David samples water from a 30 m depth, as this in the middle of the highest concentration of phytoplankton in the water column. In turn, there are likely to be high concentrations of other tiny microbes in the water which are feeding upon this phytoplankton, and he therefore hopes to collect a high diversity of microbes at this depth. David collects around 300 litres of water per sample, which he then concentrates down to a 300 micro litre volume on board the JCR, which he will use as a starting point for his genetic work back at BAS.
Briony Hull is a 1st year PhD student at BAS (QWAD project) and Manchester University. She has been collecting water samples from a range of depths in order to calibrate the salinity sensors on the CTD. She is using an onboard salinometer to measure salinity in the water column as this gives a more accurate measure than the CTD. Briony is using the information from the CTD in conjunction with data from the Acoustic Doppler Current Profiler (ADCP) to investigate currents on the continental slope. Specifically she is trying to determine if these currents are strong enough to resuspend sediment. The reason she is looking at this is because there are a number of channels present on the continental slope in Western Antarctica and she is trying to determine what has led to their formation, and whether it is possible that they are caused by turbidity currents, or by other factors, such as melt water or tidal forces. Her work is the first of this kind to be done in Antarctica.
3 April 2008 Trawling for live animals
Before reaching Rothera Research Station (a British Antarctic Survey base) on the Antarctic Peninsula we ran three short Agassiz trawls to collect live animals from a depth of 200 m for the marine biologists at Rothera. The two wintering marine biologists at Rothera, Alison Massey and Birgit Obermuller, are studying seasonal physiology of a number of animals. They are investigating how much oxygen they use and how this changes with temperature as well as changes in their seasonal processing of food. We still know very little about how animals cope with the most of strikingly seasonal of environments.
Conventional SCUBA diving permits diving to quite shallow depths but the continental shelf around Antarctic is very deep (compared with most of the rest of the world). By collecting live animals from deeper waters and maintaining these in the ambient temperature aquarium at Rothera, the marine biologists get a rare chance to compare animals in the shallows with those from deep at more typical shelf depths. We see urchins, sea cucumbers, brittlestars and sea stars. Each of these animals do not have swim bladders and therefore do not get damaged due to loss of pressure and have reasonable survival prospects. One of the species, the common red sea urchin Sterechinus neumayeri, was even the same species as found in the shallows.
5-6 April 2008 Rothera Research Station
We've just spent the last few days at Rothera research station. Rothera is in a really pretty setting on Adelaide Island off the West Antarctic Peninsula. The base is covered in snow and is dotted with Adelie penguins, fur seals and a few elephant seals. The ice in the bay is really beautiful - lots of it is brilliant blue in colour and other pieces are completely transparent - and many of them are really spectacular shapes too. The icebergs are truly an astonishing variety of colours and shapes.
We've mostly been working unloading cargo for Rothera and loading up lots of their cargo to take back to Stanley and the UK, including live animals for back at BAS and waste from the base to be disposed of. Thankfully, however, there has been plenty of time for fun in between the hard work!
The highlight yesterday was that the field assistants took us skiing! The ski run was a pretty good one and we could certainly get some pace up! The field assistants would tow us to the top of the ski run using their ski-doos and then we skied back down. The field assistants also took us to the other side of the slope where they have a little caboose where we had a hot drink and some chocolate right up in the slopes. It was a fabulous day!
The following day we left Rothera. We were the ‘last call’ at Rothera and so the 20 or so scientists and support staff on base will be there alone for the winter, with no further visits from ships until December! I think it was quite a moving moment for them to be standing on the dock waving goodbye to the JCR.
09 April 2008 - Worms, whales, wood and the Antarctic deep ocean
Adrian Glover, Zoology Department, The Natural History Museum, London. firstname.lastname@example.org
This week’s diary entry is from Adrian Glover, a scientist at the Natural History Museum, who specializes in polychaete worms and the fate of dead whales!
For a very long time, the deep sea was considered a cold, dark, perhaps lifeless realm. Much of this ignorance was based on the inability of sailships to sample the deep sea. On the James Clark Ross, we press a button to stop the ship, and another button to lower a trawl 5000m over the side. On an 18th century sailship, just stopping the ship and holding position would be a feat, let alone finding the power to deploy thousands of metres of wire. Pre-19th century mariners did not really care about the deep sea. It was enough to know there were no rocks to run into and enough water to bury the dead.
It was not until the late 19th century voyage of HMS Challenger that deep-sea biology took off - abundant and diverse life discovered at the greatest depths of the ocean, fuelled by the slow rain of dead organic material from surface waters. A century later, oceanographers sent down the Alvin submersible on the Galapagos Rift hydrothermal vent and made the second great discovery: life on an underwater volcano, fuelled by a geologically-driven ecosystem independent of the sun.
The discovery of giant tubeworms, clams and complex food-web communities at hydrothermal vents and hydrocarbon seeps completed the picture of the deep sea. A generally sedimented environment, low in overall abundance, but rich in the number of species and punctuated in time and space by habitats of startling richness and evolutionary novelty. Giant, 2m-long red plumed tube worms clinging to the sides of black smoker chimneys at up to 400 degrees centigrade. Clumps of ice-like methane hydrate in the Gulf of Mexico, fuelling bacteria and strange new species of worm specifically adapted for that environment. The unique feature of these organisms is chemosynthesis, or using chemicals (usually sulfide or methane) from the organisms geological milieu as a source of energy, rather than photosynthesis from sunlight as occurs for the majority of life on this planet. The excitement over the discovery of deep-water chemosynthetic ecosystems in the late 1970’s and early 80’s was justified, but the vent and seep biologists had missed something important. Chemosynthesis actually occurs in shallow water too, and is most frequently the result of biological activity rather than geological. In areas of low oxygen and high organic load, hydrogen sulfide is generated by the action of sediment-based sulfate-reducing bacteria. This might occur in muddy sediments just off the coast, or anywhere where there is a large and sudden input of organic material. In the late 1980’s, Craig Smith, and oceanographer at the University of Hawaii, was conducting submersible work using Alvin in deep basins of San Diego, California. On one of the dives with the small, 3-man craft, they came across what the pilots first thought was the remains of a dinosaur on the seabed. What they had found was in fact the remains of a huge fin or blue whale, it’s giant bones giving the appearance of some prehistoric monster on the submarine cameras. Even more remarkably, the bones were covered in a kind of bacterial mat known from hydrothermal vents, and vent-type organisms were found crawling over the remains of the carcass, feeding on the sulfide produced from the rotting bones. An intriguing hypothesis presented itself, potentially solving one of the enduring mysteries of hydrothermal vent biology. Could whale bones, scattered on the seabed, act as stepping-stones for the dispersal of chemosynthetic fauna across the vast distances of the abyss?
A sequence of subsequent experiments, including both implanted and naturally-found whale carcasses has shown for some organisms, over certain spatial and temporal scales, this may be the case. Even more remarkably, we have now discovered a suite of specialist whale-fall organisms, including an animal closely related to the hydrothermal vent tubeworms, called Osedax, latin for ‘bone-eating’. This organism, a polychaete worm, has no mouth or gut, but a distributed, branching root system that penetrates inside the bone matrix, and uses specialist symbiotic, whale-oil eating bacteria to gain energy. Viewed on the bone surface, the gills of the animal look like red flowers growing out of the bone itself.
Radiometric dating of whale bones on the deep seabed has shown that they may fuel a chemosynthetic ecosystem for more than 80 years - longer than the lifespan of many vent fields. The bones can be thought of as a hard substrate, like rock, but with a built-in energy supply - the rich oils that make up a large proportion of whale’s body mass, and was the source of a major biofuel industry for much of the 19th and early 20th century. Recently, we have also been looking at wood remains in the deep ocean as a comparable habitat to both whales and vents. Wood frequently washes out to sea and can be found littering the seabed along continental margins. Our early experimental studies from the California margin have suggested that they may also fuel chemosynthesis, but with lower intensity. They are also home to specialist wood-boring organisms, such as the shipworm, actually a worm-shaped bivalve mollusc.
So what of the Antarctic? The Southern Ocean that surrounds Antarctica has some of the highest whale population densities in the world. Historically, it is also the least-impacted by whaling. A very crude summary of whaling intensity in different ocean basins would put the North Atlantic at the most intense, followed by the North Pacific, and finally and most recently the Southern Ocean. One question we are interested in is whether we can use molecular techniques (specifically looking at DNA divergence in whale-fall organisms) to pick up the past impacts of whaling, given a lag-time of perhaps 50-80 years for bones to decompose on the seafloor. We are also interested to compare Southern Ocean vent and hard-substrate environments to whale and wood communities in the same area, as a further test of the stepping-stone hypothesis. Furthermore, given that wood is not naturally present in abundance in the Southern Ocean (Antarctica has no trees), can we expect wood-fall specialist organisms in this region? Can they disperse across the Drake Passage? By looking at both oak and pine degradation on the seafloor over a 3 year period, we also hope to provide insight into the fate of wood shipwrecks in Antarctica, such as Shackleton’s famous (oak) ship HMS Endurance which lies somewhere in the Weddell Sea.
With me on the James Clark Ross, I have three experimental moorings designed by OceanLab in Aberdeen, each consisting of a whale bone or wood package, and a special acoustic transponder which acts like an underwater marker beacon to any submersible or remotely operated vehicle (ROV). We will return to this area in 2011 with the UK’s new ROV Isis to survey and sample these experiments for both vent-type and specialist organisms such as Osedax and shipworms. Through a collaboration with both the Swedish Polar Secretariat via my colleague Thomas Dahlgren, and Craig Smith and the National Science Foundation, we also hope to sample them with the research ships Oden and Laurence M Gould in 2009 and 2010.
My interest in polychaete worms has kept me busy on this cruise, not just in preparing the moorings, but in working up the thousands of specimens we have brought up from Pine Island Bay and the Amundsen Sea. These include the largest predatory polychaete I have ever seen - with jaws large enough to take off a small finger. But that is another story!