This year many of the questions in Week 6 of the MOOC were concerned with the issue of marine litter, so this will be the focus of my final blog post.

The first way that each of us can make a difference to the amount of litter that is ending up in our oceans, is to be responsible about what we are throwing away:

• check what items can go in your recycling bin. Many local councils will also recycle glass and compost now so do your best to make that extra effort and use the facilities that are available;
• carefully consider where you are disposing of waste. As a general rule, only toilet paper should be flushed down the toilet; sanitary items, baby wipes, and cotton wool products do not easily break down and should always go in the bin. Read more about the ‘Think Before You Flush campaign’ run by ‘Surfers Against Sewage’ here.
• unfortunately waste cannot always be reduced, reused, or recycled, so when it finally becomes trash, think carefully about what you can do to reduce the risk of it causing harm in the marine environment. See Abbie’s excellent blog this week about how to reduce the risk of plastic bags being mistaken as food by turtles and other marine critters. Cut up plastic beer rings and bottle cap rings before throwing them out as these can ensnare seabirds. Most of the plastics used to make these ‘ringers’ are now photodegradable, but this process still takes a few months and could still do harm before they even begin to break down.

For those of you that want to go that extra mile and help to reduce the amount of litter that is currently being dumped at sea, you can join or organise your own Beachwatch events (run by the Marine Conservation Society) that help to keep Britain’s beaches clean. Or if you are like me, you can litter-pick every time you go to the beach!

You are all now ambassadors for the future health and sustainable use of our oceans, so let’s spread the word and let others know what can be done to protect our marine environment.

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Hydrothermal vents are known to occur along tectonic boundaries in the Earth’s crust, so the >56,000 km-long mid-ocean ridge system is a great place to begin our search.As you can see from the map above, very few hydrothermal sites have been discovered along the Circum-Antarctic Ridge (which surrounds the Antarctic continent). In fact, the ChEsSO expeditions to the East Scotia Sea aboard the RRS James Cook during 2009-2010 were the first to confirm the presence of active hydrothermal activity along the East Scotia Ridge and the Bransfield Strait (indicated by the red squares and star on the map). Before these expeditions, even fewer hydrothermal sites were known from high southern latitudes.

Once we are at sea in a region of potential hydrothermalism, there are three steps involved in the detection of a hydrothermal vent field.

Step 1: locate the hydrothermal plume using a CTD profiler.

In my previous post, I explained that the black ‘smoke’ which can be seen billowing from the top of a hydrothermal vent is actually hot fluid that is full of metals. This metal-rich fluid rises into the water column as it cools to form a hydrothermal plume; so if we can detect the hydrothermal plume, we known that there must be a vent nearby.

Those of you that have been following the MOOC will know that a CTD profiler is a common oceanographic tool used to survey the temperature and salinity structure of the ocean. The water in a hydrothermal plume is warmer than the surrounding deep-sea water, so positive temperature anomalies are one clue that helps us to track a plume. A CTD is often fitted with other equipment, such as a Light Scattering Sensor (LSS) and Niskin Bottles. The LSS allows us to measure the amount of light that is being transmitted through the water column: more light will be scattered in a hydrothermal plume that contains lots of particulate material, so the LSS is another useful tool for finding a plume. Hydrothermal activity releases lots of metals (e.g. iron, zinc, copper, and lead), gases (e.g. methane), and other compounds (e.g. hydrogen sulfide) into the water column that are normally present in seawater at very low concentrations. Using the Niskin Bottles, we can take water samples from different depths and analyse these back onboard the ship to see if the concentration of things like methane and hydrogen sulfide are present at concentrations higher than those of the ‘background’ seawater. If the CTD reveals the presence of temperature, plume particle, and chemical anomalies in the water column, we can be pretty sure that we are in the right area to start our search for a hydrothermal vent at the seabed.

Step 2: map the seafloor.

Many different techniques and technologies are used to map the seabed. During the ChEsSO cruise to the East Scotia Ridge, we used a multi-beam echosounder (mounted to the bottom of our remotely operated vehicle (ROV) ‘ISIS’) to produce detailed bathymetric maps of the ocean floor, from which we could identify potential vent fields.

Step 3: photographic reconnaissance and ROV sampling.

When the previous two stages confirm the presence of a hydrothermal vent, we can begin homing in on a smaller area of the seabed to video with the ROV. This is always a very exciting time to be on watch! Once the ROV has been deployed, you can spend many hours watching the dark, deep-ocean and endless seabed before the ROV-mounted camera is suddenly engulfed by a dense plume of black ‘smoke’ and you have finally found the hydrothermal vent.

Although finding the vent is a successful mission in itself, the real work is yet to begin! From here we must observe and record as much as we can about the vent environment. We use a temperature probe to measure the maximum temperature of the emitted vent fluid (which can be as high as 400°C), a titanium water sampler to extract some of the vent fluid, coring equipment to take sediment samples, suction hoses to hoover animals from the vent and surrounding seabed, and sometimes we can use the manipulator arms of the ROV to break small sections off of the vent itself to investigate its mineralogical composition.

The post How to find a hydrothermal vent appeared first on Exploring our Oceans .

“With its untold depths, couldn’t the sea keep alive such huge specimens of life from another age, this sea that never changes while the land masses undergo almost continuous alteration? Couldn’t the heart of the ocean hide the last–remaining varieties of these titanic species, for whom years are centuries and centuries millennia?” From ‘20,000 leagues under the sea’ by Jules Verne.

For me, the ocean has always meant adventure and exploration. From being engrossed in the adventures of Jules Verne’s Captain Nemo as a child, to watching live footage of previously undiscovered deep-sea vents during my PhD, the ocean has always been exciting. In part this excitement comes from what is hidden beneath the waves; the vast expanse of the ocean has enticed human curiosity for centuries and it seems that the more we learn, the more questions we have. I doubt that we will ever have all of the answers – in all our years of oceanic exploration we have barely grazed the surface, let alone delved into the “heart of the ocean”. Hopefully, all of the oceanographic questions that you have over the next 6 weeks will be answered by myself and the other MOOC mentors! So get in touch, we would love to hear about what the ocean means to each of you.

The post Laura Hepburn: What does the ocean mean to me? appeared first on Exploring our Oceans .

If you are not familiar with the term ‘hydrothermal vent’ take a look at Abbie’s excellent research blog post where she describes what a hydrothermal vent is, how it forms, and why it is so important that we study the bizarre animals that live on and around these awesome structures.

My PhD is focussed on the metal-rich sediments that we find underneath the hydrothermal vents themselves. Have a look at this image of a vent discovered during one of the first ChEsSO cruises:

Can you see the black ‘smoke’ billowing out of the top? This ‘smoke’ is in fact hot water (up to 400°C in temperature) that is full of metal! The black colour comes from lots of tiny particles of metal sulfides that fall out of the plume of black smoke onto the seabed beneath. Over time these particles accumulate and form large metal-rich deposits, full of iron, lead, zinc, copper, and precious metals like silver and gold. One of the reasons why we study hydrothermal vent sediments and other deposits is to evaluate whether or not the metal ore is worth mining from these systems – you will be hearing much more about deep-sea mining in week 6. My research uses Sulfur isotopes to work out where the sediment material has come from and whether there are any signs of biological activity within the sediments themselves. I’ll be talking about Sulfur isotopes and deep-sea sediments in much more detail over the following weeks, so be sure to follow all of the MOOC mentors if you want to hear more about our individual research projects.

I have always had an interest in Oceanography. I know that I am very fortunate in this respect as it means that I have had a very clear career path since A-levels. I studied Maths, Chemistry, and Biology to A-level and Physics to AS-level, which enabled me to study for a 4-year Master of Oceanography degree at the university of Southampton. Following my degree, I worked as a Geochemistry technician at the National Oceanography Centre, Southampton (NOCS), which equipped me with the laboratory skills that I have needed to complete my PhD at NOCS. I really enjoy my job and know that I am very fortunate to be doing something that I love, especially since it gives me the opportunity to interact with lots of different people from lots of different backgrounds. I am excited to be a part of this MOOC and look forward to hearing from you all!

The post Laura Hepburn: My research appeared first on Exploring our Oceans .