Technology for Ocean Science

Eavesdropping on an underwater world: Technology for Ocean Science

The ocean is not a quiet place.  Water can move rocks and sediment, even sufficiently to create underwater landslides.  Bivalves make clapping noises, fish make sounds during courtship, and cetaceans communicate with clicks and whistles, just to name a few.  And of course there is human activity – like shipping, drilling, and sonar, which all add to the sounds of the ocean.  There are many different reasons why we might want to hear these noises.  Thanks to acoustic monitoring technology we can.

There are many different types of acoustic monitoring equipment but you will tend to find one type of sensor at their heart – the hydrophone.  Hydrophones are microphones that can be dropped into the water and listens for sounds coming from any direction.  If you have been on a whale-watching boat you may very well have seen one of the crew drop one of these into the water.  With the hydrophone, the crew can hear a noisy whale and even work out their location.  In some places, hydrophones are anchored to the sea floor and float in the water column recording any sounds within their range, until their battery runs out and/or they are picked up again by boat.

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Marine Life, Ocean Ecosystems, Technology for Ocean Science

Known unknowns (Life in the Mariana Trench)

In the western Pacific Ocean lies the Izu-Bonin-Mariana (IBM) arc-trench system, created from the subduction of the Pacific plate which began some 51 million years ago and continues today.  The IBM is home to the deepest known point in the ocean – the Mariana Trench, which in its famous Challenger Deep, reaches a known depth of 10,994 meters (± 40 meters).  Early explorations of the Trench focused on determining its depth.  When on 23 January 1960 Swiss engineer Jacques Piccard and US Navy submariner Captain Don Walsh took the first manned vessel – the bathyscaphe Trieste, down the Challenger Deep to 10,911 metres (35,797 feet), they were uncertain whether they would make it back to the surface.  Make it back they did, and what they saw down in the Deep surprised and delighted all….

The bottom appeared light and clear, a waste of snuff-colored ooze. We were landing on a nice, flat bottom of firm diatomaceous ooze…. as we were settling this final fathom, I saw a wonderful thing. Lying on the bottom just beneath us was some type of flatfish, resembling a sole, about 1 foot long and 6 inches across. Even as I saw him, his two round eyes on top of his head spied us – a monster of steel – invading his silent realm. Eyes? Why should he have eyes? Merely to see phosphorescence? … Slowly, extremely slowly, this flatfish swam away. Moving along the bottom, partly in the ooze and partly in the water, he disappeared into his night.” ~ Jacques Piccard, Seven Miles Down: The Story of the Bathyscaph Trieste (1961).

Since Piccard and Walsh’s descent, only one other person has been to the bottom of the Challenger Deep.  On 26 March 2012, in his much more advanced deep-sea submersible the Deepsea Challenger, James Cameron reached the bottom at a depth of 10,908 metres (35,787 feet) and remained there for some 3 hours before ascending, bringing with him HD video of this rarely viewed environment.  Thanks to the advancement of robotics, exploration of the Mariana Trench does not rely solely on manned missions.  Remotely Operated Vehicles (ROVs) have provided us with images, video footage, and even samples brought from the deep.  Notwithstanding the difficulties in deep-sea exploration, at 2,550 kilometres (1,580 miles) long, and an average width of 69 km (43 miles), studying the Trench is no small feat.  But with every trip we have learned more about this unique and extraordinary environment and its inhabitants…

The full article was published in – and can be read in – The Marine Professional, a publication of the Institute of Marine Engineering, Science & Technology (IMarEST).

Image: Galatheid crabs and shrimp graze on bacterial filaments on the mussel shells. The black “scars: on the shells are former anchor points of mussels who have cut their threads and moved on. Image courtesy of NOAA Submarine Ring of Fire 2004 (Volcanoes Unit MTMNM). USFWS – Pacific Region/Flickr (CC BY-NC 2.0)

Conservation & Sustainable Management, Fisheries, Aquaculture, & Sustainable Seafood, Technology for Ocean Science

The Dividing Line (Benthic Habitat Mapping)

Our ability to map the seabed has been greatly enhanced by a suite of technologies.  Satellite technology can detect underwater mountains and trenches by measuring bumps and dips on the ocean surface.  Sonar technology determines depth by measuring the time it takes for sound to travel between a vessel and the seafloor, and back again, with the ‘strength’ of the echo providing information on whether the substrate is rock or sediment. Light Detection And Ranging (LIDAR) technologies, typically attached to aircraft, use infrared and blue-green pulsed laser beams pointed down towards the sea.  Whilst the infrared is reflected off the surface, the blue-green is able to penetrate the water column up to a depth of 30 meters (depending on water clarity).  The difference in the time it takes for the two lasers to return back to the aircraft indicates the depth.  Submersibles, remotely operated vehicles (ROVs) or autonomous underwater vehicles (AUVs) can be deployed with underwater cameras as well as designed to capture physical samples of the sea bed.  Mapping marine benthic habitats is vital for many different purposes, not least for supporting marine spatial planning and ecosystem based management of the marine environment.  Benthic maps also support industrial endeavours such as offshore oil and gas developments, mining, and fisheries management, ensuring safety for mariners by identifying hazards and designing safe shipping channels, for conservation purposes such as designing marine protected areas, identifying critical habitats, and of course improving our knowledge of benthic ecosystems…

The full article was published in – and can be read in – The Marine Professional, a publication of the Institute of Marine Engineering, Science & Technology (IMarEST).

Image: Map of ocean floor based on earths gravity field. Credit NASA (Public Domain)

Technology for Ocean Science

Underwater Observatories for Ocean Science

Studying the ocean is expensive business.  For a start, a huge proportion of the ocean is difficult for us to reach.  Even if you just want to head out away from the coast and take some samples from the surface waters, you need a boat, sampling and measuring devices, people who can operate the boat, people who can operate the devices, provisions…. You get the picture.  Then you need to take repeat measurements – which mean repeat trips.  Sampling from on or near seafloor – especially in deep water – can be even more costly.  But what if you didn’t have to keep going back and forth?  What if you could have all you need in situ, on the ocean floor?

The concept of the undersea observatory is not new.  Back in 1962, underwater researcher, filmmaker, and co-developer of the Aqua-lung Jacques-Yves Cousteau along with US naval doctor George Bond launched the first of three Continental Shelf Stations, Conshelf I off the coast of Marseilles.  Submerged in 10 meters of water, two aquanauts (Claude Wesly and Albert Falco) were able to spend up to 5 hours per day living and working under the ocean.  A year later and Conshelf II was launched, this time submerged in 10 meters of water in the Red Sea off the Sudanese coast.  Unlike Conshelf I, Conshelf II allowed 5 aquanauts to live and work underwater continually for 30 days, but was reliant on surface support.  A second unit lying much deeper at 27 meters was added to Conshelf II shortly after.  In 1965 Conshelf III saw 6 divers living much more self-sufficiently some 102 meters below the Mediterranean Sea for 21 days…

The full article was published and can be read in The Marine Professional – a publication of the Institute of Marine Engineering, Science & Technology (IMarEST)

Image: NEEMO 12 crewmembers survey the exterior before entering their undersea habitat as they begin the 12th NASA Extreme Environment Mission Operations (NEEMO) mission. Credit NASA Johnson/Flickr (CC BY-NC 2.0)

Citizen Science, Conservation & Sustainable Management, Fisheries, Aquaculture, & Sustainable Seafood, Technology for Ocean Science

Multi-tasking underwater

Often when I say to people I do underwater biodiversity/habitat surveys, they have an image of glorious tropical seas, great visibility, and general ohhing and ahhing at the beautiful marine critters. The reality is somewhat different (especially when you’re not in tropical waters!).

A small team of intrepid divers are currently undertaking maerl surveys at an offshore reef, just off the coast of Jersey (Channel Islands).  Maerl is a hard red seaweed, that forms little blobs.  It’s a super important habitat for our smaller ocean brethren, and super slow growing too.  On this particular survey, my job was to conduct a general habitat and species survey of the site, and keep hold of the SMB – basically and inflatable sausage attached to the end of the line you can see me holding that sits on the surface of the sea so we can be spotted.  You can see that the visibility wasn’t that great, but what you can’t see is the current that was trying to take me one direction, whilst the wind was pulling the SMB the other.  This is why I’m kneeling on the seabed so I could make some notes on the board I am holding, whilst also making sure I don’t let go of the SMB!

Image: Taken by Kevin McIlwee/Jersey Seasearch

Marine Life, Technology for Ocean Science

Biodiversity in the high seas. We know it’s there but how do we quantify it?

When I was younger, the term “high seas” conjured up images of pirates, and big galleons, and sea monsters.  Perhaps a little less exciting to my younger self, the high seas are actually international waters – those that lie outside the Economic Exclusive Zone (EEZ) of any country (for a map of the world’s Economic Exclusive Zones, head over here).  The area of high seas is vast – comprising 58% of the ocean, so it’s not surprising that the high seas are full of life.  Just like inside EEZ’s, the high seas area heavily utilized by people, and just as in our own waters, marine biodiversity needs protection to ensure its long-term persistence.  Sounds good so far.  Leaving aside the political issues of managing human activity in international waters, there are problems for effective conservation – assessing where areas of significant biodiversity are to implement meaningful areas of protection.  Some of this is down to logistics – like the cost of sampling areas of the ocean far from land.  Some of this comes from the high mobility of marine species that are found in the high seas; if we see them here today, they are probably somewhere else next week.  Some of these critters are undergoing migrations, some change location depending on where in their life cycle they are, and some appear much more ‘free’ (though aren’t wandering around aimlessly).  If our knowledge gaps on marine biodiversity in coastal waters are big, they are vast when it comes to the high seas.  We need a plan, and we need it sooner than later.  And integral to that plan, argue Ei Fujioka and Patrick Halpin, both from Duke University, is a “publically accessible online framework that provides interactive tools to assess marine biodiversity from a variety of perspectives”.  There wasn’t one, so these guys set about setting a prototype up.

Ei and Patrick are no strangers to the mapping of marine critters, and already heavily involved in OBIS – a repository of marine mammal, seabird and sea turtle observations from across the globe.  Running for over 10 years, it has more than 2.9 million records for some 311 different species.  The data within it comes from a number of different sources, such as photographs, and tagging animals.  Some of the data gives on-off records of sightings, some tracks individual movements over a period of time.  This is a veritable treasure-trove of data, and some relates to the high-seas.  The next step is to pool all of this data together into something usable, something succinct, so that researchers – and indeed the public – can understand where our fellow marine critters like to hang out, where the areas of greatest biodiversity are.

There are actually many ways of measuring biodiversity.  The simplest is species richness – simply a count of the number of different species found in any given sample.   This does not take account of the relative abundance of each species – known as species evenness, so for this there are a number of different indices, each with its own formula for calculating diversity.  Alongside species richness, the researchers included 3 of these indices into the mapping – the Shannon-Wiener, the Simpson, and the Hulbert index.  This is quite handy.  With different ways of quantifying how much diversity, like-for-like comparisons can be more difficult.  Providing a range of indices allows the data to be used in more ways than if just a single index was provided, and crucially because all areas have the same indices, they can easily be compared on a like-for-like basis.

Of course no prototype is complete without a case study.  For this, Ei and Patrick chose the Sargasso Sea – a high seas gyre ecosystem in the mid-North Atlantic Ocean that is named after the floating mats of Sargassum – a brown seaweed that accumulate there.  Previous work by a number of different researchers has already indicated that the Sargasso Sea is a key are for biodiversity,  and the OBIS-SEAMAP data-house itself hold some 5,825 observation records, and 32 datasets for this area.  These records go from 1966 to 2013, making it possible to assess how biodiversity across the four indices (Hurlbert, Shannon, and Simpson, and species richness) has changed decadally (every 10 years).  The indices that took into account species abundance – that’s Hurlbert, Shannon, and Simpson – all pointed towards a decline in biodiversity since the 1960’s (excluding the 1980’s – they only had one record for that year, so assessment couldn’t really be done), with an increase in the 2010’s.  Species richness on the other hand was a bit more all over the place.  This may partly be down to ‘effort hours’ in collecting the data, which has a statistically significant impact on species richness scores, but not on the other 3 indices.  But crucially the case study has demonstrated that it is possible to bring together different datasets to produce some meaningful analysis, and present it in a format that is useful for the public and researchers alike.  This pooling together of data – particularly high quality data – is useful for all types of ecological study and conservation planning.  Where data is much sparser, just like on the high seas, pooling together is even more important.

Ei and Pat also note that the prototype is flexible, and can incorporate all sorts of different measures of biodiversity, tailored to achieving different goals and objectives, or answering questions to guide us in making good conservation decisions.  As a prototype, its pretty good.  Don’t forget the OBIS-SEAMAP is also publicly available, and free to use – so why not have a play yourself.

The original paper appears in the journal Endangered Species Research.  The researchers have paid for the paper to be made open access – you can access it here http://ow.ly/yhYd0 .

Image:  This little critter is a White backed Planes minutus.  They can be found living on the sargassum weed throughout the Sargasso Sea.  Credit Eric Heupel/Flickr (CC BY-NC-ND 2.0).