Wednesday, 26 November 2008

Anchors Aweigh!

Leg 2 of Cruise 3 of the ASCLME survey aboard the R/V Fridtjof Nansen gave NOAA’s Pacific Marine Environmental Laboratory (PMEL) in Seattle, Washington the opportunity to deploy two ATLAS moorings in the western Indian Ocean. The first mooring was installed at a nominal location of 8°S, 55°E on 21 November 2008 and the second at 12°S, 55°E on 22 November 2008. These moorings are part of the Research Moored Array of African-Asian-Australian Monsoon Analysis and Prediction (RAMA), which is a multi-national effort to provide key oceanographic and marine meteorological data sets for monsoon research and forecasting. The goal is to span the Indian Ocean with an array of 46 such moorings between 15°N to 25°S. The cruise also provided the opportunity to deploy 4 Argo floats along the cruise track between the moorings. These are first PMEL Argo floats in the Indian Ocean and they fill a significant hole in Argo data coverage.

PMEL had never deployed an ATLAS mooring from the Nansen, so there was an element of suspense as to how the difficult and time consuming the operations might be. However, the surprises in store for us were all pleasant. Both deployments proceeded flawlessly, and in each case it took less than 5 hours from the time the buoy was placed in the water until the time the anchor was dropped. These successful operations were the result of a great team effort involving Mooring Technician Steve Kunze from PMEL who supervised the deployments; Chief Bosun Helge Dahl and his crew who masterfully carried out the work on deck; Captain Kjell Sandøy and his officers who were superb at maneuvering the ship in changing winds and currents; Data and Information Consultant Lucy Scott who applied her GIS skills to map echo sounder data during our pre-deployment bathymetry surveys; Chief Acoustician Tore Mørk who provided Lucy the ship’s log files during the surveys; and all the scientists who eagerly pitched in to help out on deck.

ATLAS moorings were developed at PMEL in the early 1980s and have been updated over the years with improved sensors, materials, and design. The mooring consists of a 2.8 m donut shaped float on which is mounted a 4 m high tower for meteorological measurements. The upper 700 m of the mooring line is plastic jacketed steel cable to protect against shark bite and to provide a conductor for electronic transmission of subsurface data to the CPU on the surface float. Below the steel cable is 3-4 km of nylon rope attached to a 3 metric ton anchor made of old railroad car wheels. Just above the anchor is an acoustic release that when triggered will detach from the anchor for easy recovery of all the instruments and mooring line.

ATLAS moorings measure surface wind speed and direction, air temperature, relative humidity, solar radiation, rain rate, sea surface temperature and conductivity, temperature and conductivity at several depths in the upper 500 m, and ocean velocity at 10 m depth in the surface mixed layer. Data are transmitted to shore in real-time via NOAA’s polar weather satellites and are available to researchers and operational centers world wide. You can view and download these data at
http://www.pmel.noaa.gov/tao/disdel/disdel.html







Thanks to ASCLME and the R/V Dr Fridtjof Nansen, RAMA has increased from 20 to 22 moorings and the array is now nearly 50% complete (See Rama figure below). Also in place is a fruitful partnership between PMEL and ASCLME for interdisciplinary studies in ocean circulation, climate variability, and large marine ecosystems of the western Indian Ocean. This is oceanography at its best! Schematic of RAMA as of November 2008. Solid symbols indicate those sites occupied so far. Color coding indicates national support, with year of first involvement shown in the upper right box. Open symbols indicate sites that are not yet instrumented.

Plate captions:
Top: First ATLAS bouy going over the side
Middle: Steven Kunze, Tommy Bornman & Ryan Palmer attaching temperature sensors to the mooring line
Bottom: Acoustic release ready for deployment
Left: The ATLAS succesfully deployed
Right: Steven Kunze and Mike McPhaden deploying an ARGO float

Text by: Mike McPhaden, NOAA/PMEL
Photos by: Lucy Scott, Isabelle Ansorge & Tommy Bornman

Tuesday, 25 November 2008

Land ahoy!!

The 41 day Mascarene Plateau Cruise finally came to an end on 16 November after sampling in amongst the islands of the Seychelles Group for more than a week! Passing close by lush tropical islands covered in palm trees with inviting golden sandy beaches was almost too much to bear!

All the scientists that participated in Leg 1 of Cruise 3, Mascarene Plateau, are shown in the image below. They are from left to right: Michelle Etienne; Oddgeir Alvheim; Helena Francourt; Denis Tweddle; Ole Sverre Fossheim; Marek Ostrowski; Tore Mork; Isabelle Ansorge (Local Chief Scientist); Vimal Ramchandar; Vikash Muibodhe; Vincent Lucas; Kim Bernard; Sven Kaehler; Riaan Cedras; Jackie Hill; Tommy Bornman; Morgane Perri; Rodney Govinden & Tore Stromme (Cruise Leader).

Most of the scientists and crew (minus the Seychellois participants that preferred to go home for a well deserved rest and local cuisine) went out that evening to paint Victoria red! I'm proud to say we partied like true sailors that have been at sea for too long & some only returned to the ship as the sun came up! The next day was spent exploring the beautiful Island of Mahe. Below are some of the photos taken in between eating crab curry & swimming at near pristine beaches.











The R/V Dr Fridtjof Nansen remained in port for 3 nights to bunker fuel, change ship and scientific crew, take on supplies and officially launch the ASCLME Programme in Seychelles. We conducted tours of the ship for school groups, scientists from local research institutions and local dignitaries. Due to heavy rain the launching ceremony was held at the Convention Centre and it was a great success! Our sincere thanks goes to the UNDP office in Seychelles for organising the event and also to the local Seychellois scientists (Michelle, Helena, Vincent and Rodney) for making the whole day a success!


Text and photos by Tommy Bornman

Interesting results!

Having now surveyed the entire Mascarene Plateau we have a better understanding of its influence on the surrounding ocean environment. What have we learnt..

It appears that the SEC is displaced southwards from its mean position of 10°-16°S by the obstruction caused by the shallow bathymetry of the Mascarene Plateau. Upstream of this Plateau the SEC exists as a broad (~650 km in width) shallow (~1000 m in depth) current with speeds averaging 0.30 ms-1. On approaching the Mascarene Plateau the SEC splits into separate cores centered near 18°, 12° and 8°S. Once passed the Plateau it seems likely that these cores continue westwards towards the Madagascar coast at 50°E and there form the North East and South East Madagascar Currents.

Deep channels separating individual banks (see past blog) act as choke points funneling the flow of the SEC from east to west.

Atmospheric circulation as a result of the SE trade wind field results in a gradual shoaling of water masses between 15°-5°S. The thermocline depth changed from 250 m close to Mauritius to just under 30 m on the Seychelles Bank. Since nutrients increase with depth, it would be expected that nutrient levels would gradually increase with distance north thus influencing the biological productivity of the surrounding region. This probably explains improved fish catches as we moved closer to the Seychelles!

Finally, the presence of an eastward flow between 6° - 2°S (blue box) can be related to the position of the eastward flowing South Equatorial Counter Current. This current lies north of the SEC and flows in the opposite direction. This proved to be extremely interesting with salty warm water being swept into the Seychelles region from as far away as the Arabian sea!
Image captions:
Top Image: General circulation over the Mascarene Plateau (The 1000 m isobaths is shown in red). Note the influence of the deeper channels speeding up the surface flow downstream of the plateau (highlighted by the green boxes)– exactly what we had hoped to find! The blue box shows the prevailing eastward flow associated with the South Equatorial Counter Current.
Bottom Inage: After 55 days this is what the drifter data looks like! See how they all race westwards through the main gaps with the South Equatorial Current. The really interesting pattern is actually just south of the seychelles where two drifters seem to be caught up in the eastward flowing South Equatorial Counter Current.
Text by Isabelle Ansorge

Saturday, 22 November 2008

Copepods run the world!

Between trawling for new fish species, photographing seabirds and whale watching, it’s easy to forget that some of the oceans most interesting creatures are only seen clearly through the lens of a microscope. In fact much of the oceans diversity can be found within the group of animals we refer to as zooplankton. Copepods, krill, amphipods, tiny fish larvae, baby decapods, polychaete worms and pelagic snails are only a few of the organisms that we have pulled from the water column by use of a bongo net, and of all these animals the copepod stands supreme. The copepod (see photos below) is a small crustacean with a tear drop shaped body, long antennae and an armoured exoskeleton and although there are a number of carnivorous species, most copepods are predominantly herbivorous. In terms of biomass, copepods are rivaled only by Antarctic krill (Euphausia superba) and contribute an enormous amount of protein to oceanic food webs. Herbivorous copepods form one of the most important trophic links in the oceans, because they graze on minute algae and in turn are fed on by larger zooplankton and fish, making the energy found in phytoplankton (which is fueled by nutrient inputs and the sun) available to rest of the oceanic food web. Without copepods, we would have no whales, dolphins, seals or fish and so, in essence, copepods run the world.

Images: Left: Pontella sp. Middle: Euchaeta sp. Right: Sapphirina sp.

Text & photos by Jackie Hill

Tuesday, 11 November 2008

Size does matter!

Indeed it does, and whoever says otherwise is no fisherman. After 31 days of zigzagging across the Mascarene Plateau, we finally made it onto the Seychelles Bank, the northernmost bank of this crescent shaped plateau. It was at 10:57a.m. on Friday 7th November when we cast our first trawl in the crystal clear turquoise waters of the Seychelles. The trawl was hauled 30 minutes later and one could not help but glow with pride once its content were scattered onto the deck. Even from afar one could not have mistaken those reddish coloured fish trashing about. 5 huge red snappers (Lutjanus sebae); the smallest weighing 7.2Kg and the biggest over 12Kg. Enough to please any fisherman. Another interesting component of this catch was an outstanding grouper (Epinephelus sp.), weighing 7.2Kg. The catch consisted of a variety of fishes of all sizes and colours of the rainbow. Compared to previous hauls done on the Nazareth and Saya de Mahla banks, this one won a myriad of attention from everyone onboard both for its size and diversity.

After being out at sea for so long, and seeing those snappers, a well sought delicacy in the Seychelles, we couldn’t help our mouths from watering as we started to discuss the best way to savour those “Bourzwa”, as they are known locally. Having one on the barbecue grill during a sunday afternoon picnic on one of our many sandy white beaches seemed to win most votes.

Today Sunday 9th November has been a memorable day. Firstly, seeing the captain raising our national flag while sailing in our waters was really nostalgic! Furthermore, seeing the inner islands on the horizon welcoming their children home were surely those moments that really make you appreciate where you come from. We stand tall today as we are fortunate to be part of this scientific team carrying out the first exhaustive research expedition of the Mascarene Plateau. Although the practical side of the research is almost over, the task has just begun as we move to the data analysis phase and get those pens onto papers to prepare numerous reports.
It is a long and tiring cruise but so far it has been a great working and learning adventure.

Rodney Govinden and Vincent Lucas (Fisheries Scientists, Seychelles Fishing Authority)
Helena Francourt and Michelle Etienne (Research Officers, SCMRT- MPA)

Monday, 10 November 2008

SWIM DEEP-SEE BIG

From marine scientist to oceanography
What a transition!!!!! I work in the Marine Science Division at the Albion Fisheries Research Centre viz. marine chemistry and bacteriology laboratory (coastal water pollution) and monitoring of corals, coral reef fishes, and marine invertebrates, study on seagrass ecosystem, and other associated research work around the beautiful island of Mauritius. Then came a moment of transition when I was selected to attend a training course on Oceanography at the University of Cape Town, July 2008, consequently I ended up on R/V Nansen for a 45 days research cruise, October 2008 onwards.

Never had I thought of being on such a long cruise but believe me, it becomes really
very interesting after a few days of adjustment (sea-sickness, that what’s make the difference between being at sea from land) and which is inevitable. Never mind, I am constantly learning from each and every person here on-board.

What is it like to be on ASCLME, R/V Nansen Research Cruise 2008?
After having obtained an intensive one month (July 2008) training course on Oceanography at the University of Cape Town by professionals and having been exposed to various oceanographers and scientists, being on R/V Nansen have been always pleasant. Learning has been the engine for motivation and below is some of my personal interpretations of major observations as an amateur oceanographer:

What is oceanography?
It is the study of the ocean or part of the ocean by relating the physics, chemistry and the biology to understand the inter-connected dynamics and sustainability of life. In general it is the connectivity between the earth, ocean and atmosphere.

What you need to be an oceanographer?
Physically fit, good observer, good knowledge of science, computer literate, dedication to work non-stop, eager to learn, above all love for the ocean, and the ability to spend weeks or months on board research vessels, at times, face harsh weather conditions, are the main characteristics that one need to have to be a committed and successful oceanographer.

W hat should you expect on-board a research vessel?
Be ready to meet crew members, technicians, scientists and oceanographers from different countries, with different accent and different sense of humour, however all dedicated professionals are united with only one goal which is to make the cruise a successful one and achieve the scientific objectives.

What would you see in an oceanographic research cruise?
Beside the blue sky, the burning sun and the blue sea, you will always find computers in every corner, paper filled with numbers, maps and plots, colorful graphical interpretations, bathymetric maps, filtration apparatus (phytoplankton, zooplankton, meso-zooplankton), chemicals, formalin, acetone, fish specimens in most part of the working places. Also ODV-based graphical interpretations stuck on the laboratory walls together with altimetry data (ocean current patterns) make the laboratory much more colorful.
Vikash Munbodhe (AFRC)

Importance of computing Knowledge in Oceanography
In this world of Information Technology, there exists no science without the use of computer, software and programming. Hours I spend in the acoustic to retrieve information from satellite data, data collected from the echo sounder and current pattern from the Acoustic Doppler Current Profiler from the vessel mounted equipment. All these have only been achieved from the proper training I received on-board the Nansen from professional programmers.


I became fascinated by the real-time data which are amazing when just after playing with the keyboards, one can get so much information in form of colorful graphical interpretations, depth profiling and current patterns. Acoustics is important in ocean studies as major changes in the current pattern, temperature and real time bathymetric data are obtained with the proper interpretation of the data obtained from satellite and other sources and interestingly I am able to do it now.

In short these are the activities that are taking place on ASCLME Nansen Research Cruise: Acoustic, CTD, Bongo, Multinet and trawling are the core activities for the research cruise. Acoustic is mainly related to the mapping of seabed using echo sounder, taking measure of the ocean current by the use of Vessel-mounted Acoustic Doppler Current Profiler and data collection from satellite drifters, deployment of CTD at particular station.

CTD is an instrument which is deployed at a specific point to a certain depth whereby the sensors collect data on physical characteristics such as conductivity, temperature, dissolved oxygen, water density, and others. The CTD also has 12 Niskin bottles which are triggered from the Acoustic Centre to collect water samples for biological and chemical analyses.
Vimal Ramchandur (MOI)

Hey no need to get panicked!!!!!!!!!!!!
You also get good delicious food and cakes (and a gym to get rid of it again), movie time, time to socialize,
BBQs as well as internet connection, so guys we are close to you and permanently updated. You will constantly be in contact with whales, sharks and dolphins and with lovely colorful fishes following demersal trawls, however at times you can also see very scary and bizarre ones.

So don’t be a loser, join us, see life differently, ASCLME & R/V Dr Fridtjof Nansen, Exploring Mascarene Plateau, Indian Ocean 2008.

OOPS!!!!!!!!!!!!!!! Hey HAPPY BIRTHDAY VIMAL, my country mate is getting one year older today

Vikash & Vimal
Mauritius

Wednesday, 05 November 2008

New fish species

Since writing my earlier account of the first few days of trawling we have been very busy sorting and identifying catches from the 24 trawls carried out to date. We are now reaching the stage where, although every trawl has brought up at least one extra species for the collection, we are becoming very familiar with the fauna as a whole. I am therefore able to spend more time on collecting, pinning out fins, and preserving fishes to obtain good representative samples of a size range of each species. I have been in regular email contact with Phil and Elaine Heemstra, the editors of the forthcoming Fishes of the Western Indian Ocean books, and delight in presenting them with photos of fish that are proving difficult to identify. They, in turn, are sending these photos to their various expert contributors to get their opinions. It certainly looks like there will be several new species to be described, and here are just a few of the more interesting fishes we are struggling with.

Nemipterus sp., resembles Nemipterus bipunctata which occurs off Mozambique, but that species lacks the distinctive yellow facial markings of this fish. These markings are reported as important distinguishing characters of this genus in the Indonesian/Australian seas where numerous species occur.

A species caught in one trawl only, does not resemble any known species from the Indian Ocean.




A large (50 cm+) snapper, Lethrinus sp., with very distinctive lips. We caught two in one trawl. The species does not appear in the FAO guide to the snappers of the world and the photo has been sent to the expert on these fishes for comment.





A stingray with completely smooth skin and uniform colouration (markings on back are trawl damage). These features do not fit any known Dasyatis species.



A large, 40 cm+, sparid bream provisionally assigned to the genus Dentex. We caught three of these from two trawl stations.






This very delicately coloured flatfish belongs to the genus Parabothus, but will have to be sent to an expert to determine its true identity. There is a strong possibility that it is a new species. These are the only two specimens collected.



In addition to apparently new species, we have lots of interesting species to sort later in the laboratory back in Grahamstown. In pelagic trawls near the surface we catch lots of small juvenile fishes that are difficult to link with adult stages. The remarkable photo is of a completely transparent flatfish caught in a trawl at the surface, where the total depth was 2800 m. Flatfishes are bottom-dwelling species once they have metamorphosed into the adult flatfish form with both eyes on one side of the head, but here we caught several of these fishes completely metamorphosed into adult forms and still living a pelagic life at lengths of 3-4 cm.

The snake blenny, Xipharias stelifer, is a remarkable fish that lives in burrows in the sand. We caught four at one site.



These are just a few examples of the biodiversity in this part of the Indian Ocean. We haven’t counted the number of fishes collected on this survey yet but the total is now well in excess of 150 species.
By Denis Tweddle & Oddgeir Alvheim

Tuesday, 04 November 2008

Suntan? What suntan?



Pas de cétacés en vue…..

Après plus de trois semaines de croisière, les cétacés se font malheureusement toujours désirer. En effet, ont pu être observés depuis le depart de l’Ile Maurice, uniquement: un groupe de baleines à bosse (Megaptera novaeangliae); deux baleines, reperées par leur souffle mais malheureusement trop éloignées pour pouvoir être identifiées; et un groupe de grand dauphins (Tursiops truncatus) venus jouer à l’étrave du bateau. Il semblerai que les zones prospectées ne fassent pas partie de leurs zones de prédilections. Les conditions météorologiques ne facilitent pas non plus les observations. La mer est souvent agitée et il pleut régulierement, ce qui limite considérablement la visibilité.

Still no cetaceans in view….
After more than three weeks of cruising, we are still hoping to find cetaceans. Since leaving Mauritius, we have observed only a group of humpback whales (Megaptera novaeangliae); two baleen whales (unfortunately too far away to be identified) and a group of bottlenose dolphins (Tursiops truncatus), which came to ride the bow waves. It seems that the areas under investigation are not some of their favourite. Weather conditions also don’t help for observations; the sea is often rough and it is regularly raining, limiting the visibility.

Text by: Morgane Perri
Photo: Tommy Bornman

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