As most people know atmospheric CO₂ levels are increasing, whether this is cause for concern depends upon your opinions on climate change. For the purpose of this article (and because I’m an environmental scientist) we will push forward with the knowledge that the increase of CO₂ is caused by humans. It is suggested that it might already be too late to reverse the changes high CO2 levels will have on our environment but also that there just might be some time. Prevention of high CO₂ emissions is the best option, however extremely hard to accomplish with countries having different political views and our comfort in our modern lifestyle and thevtechnological age we live in.

Geoengineering is the term encompassing all proposals to remove CO₂ from the atmosphere for long periods of time. They include irrigating the Sahara to plant trees, pumping deep nutrient rich waters to the surface ocean, iron fertilization in the ocean, pumping liquid CO₂ into rocks, putting giant reflectors into orbit and many more. Here we will focus solely on iron fertilization (addition of iron) of the ocean.This works as phytoplankton are often inhibited by iron, particularly in the Southern Ocean and some parts of the Pacific. Iron is needed for them to be able to photosynthesise, and if it is the only limiting element, then its addition should create huge phytoplankton blooms. Also needed for photosynthesis is inorganic carbon, which for phytoplankton comes from the atmosphere and dissolves in the sea. Therefore, during blooms phytoplankton are locking in atmospheric CO₂. This is all very well and nice, but what happens to the CO₂ when the blooms subside? This is the crucial part.

Phytoplankton sink from the surface to the deep ocean as dead cells which often clump together to form large aggregates of phytodetritus. If the entire phytoplankton community ended up buried on the seafloor and in the sediments, atmospheric carbon dioxide could be locked away for millennia. However, phytoplankton are the base of many marine food webs and so only a tiny fraction (1-10 %) is removed for significant timescales.

Bacteria and zooplankton are the initial utilizers of this sinking organic pool of carbon. Bacteria can attach themselves to aggregates or be free-living, but ultimately solubilize the particulate organic carbon and depending at what depth this occurs, the carbon can be remixed back to the surface and if in its inorganic form, be a source of CO₂ to the atmosphere. Zooplankton consume the sinking phytodetritus and so the carbon is converted back to CO₂ through respiration or is assimilated, egested as faeces or excreted. However zooplankton are also a contributor to the sink of organic carbon as their faecal pellets sink through the ocean with the phytodetrital aggregates. However they too can be eaten, sometimes by their producers! So you see there are lots of biological factors effecting how much carbon reaches the deep, and the addition of regional, seasonal and temporal variation shows its not a straight forward process to understand.

Pros and Cons

A recently published paper in Nature by Keller et al. (2014) showed model simulations for 5 different geoengineering options including iron fertilization (see figure). Rising CO2 and temperature would be slowed, but only slightly but the largest change would be in O₂ concentration, which would decrease, the largest decrease of the 5 types. However if iron fertilization ceased there wouldn’t be a dramatic increase in temperature or CO₂. So whilst this paper showed iron fertilization would decrease CO₂ and temperature, for such small amounts and short time scale is it worth the risk when we know so little about how it would work and what the side effects to the oceanic ecosystems would be? Some of the possible side effects include, changes in phytoplankton species which will have an affect on the food web, increased fish stocks, harmful algal blooms, more jellyfish, production of nitrous oxide and methane and nutrient depletion elsewhere when fertilized waters resurface.

Ignoring side effects, we STILL (after 12 experiments) do not know if it would be successful. Ship budgets and schedules mean scientists observe the increase in phytoplankton biomass after iron addition, but miss the subsequent sinking of carbon to the deep. Natural experiments where iron isn’t added but a naturally iron replete area and deplete area are compared, are good examples, such as in the Crozet experiment in 2004-2005 in the Southern Ocean. This experiment showed at times a 10 x increase in the carbon flux to the deep ocean in the iron replete area. However this occurred during Antarctic spring and who knows if such large increases would persist throughout the whole year.

Another additional problem is legality. There are strict laws on dumping anything at sea and even though these experiments have been done in international waters, there are still legal obstacles to overcome. Especially in Antarctica, which might even, become a marine protected area if politicians can work out their differences!

In my opinion ocean iron fertilization is not the answer to decreasing the atmospheric CO₂ levels. Gaining international approval, understanding the long term effects of the local and non local ecosystems and quantifying the effect it will have are all still questions scientists face after 2 decades of work and experiments. I actually do not think I will witness any successful geoengineering solution in my lifetime – and I’m only 25!

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Plastic is a serious issue in our oceans. We produce so much of it across the globe and unfortunately a lot ends up in the sea. It becomes wrapped around mammals for years deforming their bodies, eaten by turtles that mistake plastic bags for jellyfish or ingested as microplastics, which can release toxins. Plastic takes 500-1000 years to degrade, so it isn’t going anywhere fast.

Currently in the Pacific ocean there is a huge build up of plastic that gets trapped in currents in the gyres and circulates the ocean. Up to 8 % of seals and sea lions can be entangled in plastic and many marine mammals and birds ingest plastic. But who is responsible for removing it? It arrives in international waters where no one is obliged to remove it. A young entrepreneur from Holland has written a proposal for ‘Ocean Cleanup Array’, a device to hoover up plastic and debris from the surface waters but allows animals to swim through. This venture has received a lot of publicity, not all good and is still a long way off from being a reality, but it’s refreshing that someone is attempting to solve this issue.

The ideal solution would be to reduce plastic production, but there is such a high demand from society for plastic; plastic production increased from 50 million tons in 1950 to 245 million tons in 2008. It’s a similar issue with climate change – do we stop the cause or treat the outcome? Water bottles are one of the biggest problem especially in countries where it is common to drink bottled water, such as the USA.

Alternatively the threat from microplastics is not as obvious to the eye but equally devastating. Microplastics are small (< 5 mm) plastic beads, granules, fibers and fragments that are easily ingested and often result in the consumer not eating normal prey which can cause reduced energy levels and possibly death. Microplastics can also enter animals through the gills due to its small size and the prevalence can be up to 80 % in some species. Humans are at risk too as plastics can be toxic and build up through the food chain, some of which we consume such as fish. Microplastics are either broken down from larger items such as plastic bottles or microbeads from soaps that are designed to be washed down the drain. The term was only coined in 2004 by Prof Richard Thompson (ScienceDaily.com, 2014) but scientists are seriously concerned with their physical and toxic effects to marine life and that we need to ‘turn off the tap’ of plastic to the marine environment.

It’s easy to reduce our personal usage and waste of plastic. Here are some examples:

• Reuse plastic bags when you go to the shops or use canvas bags, for food AND recreational shopping
• Don’t drink from plastic bottles or cups, remember to reuse coffee mugs and most coffee houses will fill your own mug
• Don’t litter
• Get involved in beach cleans or do one yourself
• Don’t buy cosmetic scrubs with beads
• Buy eco-friendly cleaning products, which are often refillable
• Recycle your plastic if possible

It’s so important we realize the effects of our consumption have on our planet, together we can make a difference!

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I imagine most people would say if they had the chance to work at sea on a state-of-the-art research ships that it was a great opportunity… to miss the Great British winter! Clear blue skies and temperatures never below 27°C in January, it was bliss. We sailed from Balboa adjacent to Panama City on 28^th December southwest into the Pacific and then headed north for the seas off Guatemala. Just getting onto the ship was an eventful nighttime drive around Panama, all of us oblivious to what was going on. Whilst in the minibus it was discovered email, internet and telephone use may not exist for some/all of the cruise due to being in the wrong area for the satellite we were currently connected to. Whilst some saw the potential benefit of this, 7 weeks at sea with no contact from home was not a great prospect. Thankfully after much hard work by our IT technician and a lot of running from the bottom to the top of the ship, connection with the outside world was restored.

Research ships are nothing like cruise liners or what you might imagine, there are no climbing walls or ice-skating rinks, however they are often a lot of fun along with a lot of hard work. Most of the British research ships have single cabins, with a large single bed, sofa, maybe sink and if you are really lucky your own en suite. Meal times are strict and somewhat early, 730 breakfast, 1200 lunch and then 1730 for dinner. The staff in the galley (kitchen) cook wonderful food so there is a buffed with a huge selection for dinner, often resulting in a 3-4 course dinner. Thankfully there is a small gym on board to work off all the food!

Scientists onboard research ships are often taking samples for completely different experiments or measurements to each other but all with the same end goal of how to understand a certain system better. A typical day for me usually starts on deck at 6 am ready to deploy my first ‘marine snow catcher’ of the day. This is basically a glorified 350 L water bottle used to collecting sinking organic particles from the upper to mid ocean. After deploying 2 snow catchers I go straight to the lab with lots of bottles of water and start filtering. I deploy maximum of 4 in 24 hours, as it’s a long process to filter and then identify all of the particles. If I’m lucky I can finish before dinner but often I may have to do an hour or two after. Once finished for the day our options are either to go to the bar (where alcohol units are strictly limited to 2 units a day for women and 3 for men) or dvd room where there are a few hundred dvds to choose from. Evenings can sometimes get repetitive so we have to keep ourselves entertained with different card games or darts e.t.c. The brand new ship even has televisions in most of the cabins!

On this particular cruise New Year’s Eve was only a few days after sailing and a great way to hasten bonding between the crew and scientists. The day was as normal but for the evening the galley staff went all out. The mess (dining room) was converted into a restaurant with fairy lights, the tables set and even bottles of wine for laid out for us (thankfully unit allowance was ignored). Once we had finished our set menu, canapés and champagne were served in the bar where most people stayed for the evening. At midnight we gathered around the newly polished bell and the eldest onboard rang out the old year and the youngest rang in the New Year, shortly followed by the traditional singing of Auld Lang Syne. Most then went to bed as science started the next day, an unfortunate coincidence for some!

A few days after leaving land Mike and Manuela discovered the laser in their flow cytometer was not working. This was a massive blow to all the scientists on board as this piece of equipment was going to be used to intelligently sample the water at high resolution where bacteria numbers peaked. Due to our close proximity to land, Mike was able to order a replacement from Southampton to be delivered to Guatemala. Unfortunately it did mean almost two-thirds of the cruise went by without use of this piece of equipment.

 The day before we headed into port in Guatemala, a long line from a small fishing vessel got caught around the bow of the ship. The fishermen were able to cut their end free and sail off, after offering us a tuna or two of course. Mark (chief scientist) and the crew previously experienced 10 days adrift in this area during ‘Part 1’ of the project after a long line was caught around the propeller. So it was definitely a concern to all. As we were due in port the next day it was arranged that divers would come and remove the line from the ship. Mark also had to prepare a presentation explaining the science on board for officers from the Guatemalan Navy. A few came on board for an hour or so and left, leaving one of their lieutenants with us, Paco, for two weeks. With a degree in hydrography he knew a thing or two about the ocean and was very interested in all we were doing on board. However even he was complaining about the heat and he was a local!

We also had two medical evacuations within a few days of each other, the third engineer and the head chef. Due to this on a quiet morning I offered my services to the galley and was in charge of chopping and grating for salads. At 5 weeks in fresh vegetables were dwindling and the creativity levels had to be increased. Working in the galley for only a short amount of time certainly makes you appreciate your meals more.

When not deploying, filtering, spiking, killing, photographing or analyzing a favourite past time some of us was to frequent the local pool/jacuzzi/fountain. The engineers fashioned a pool, equipped with pipes for air bubbles around the perimeter and a fountain feature. Not forgetting of course the obligatory giant blow-up Nemo that resides in it. The pool was filled using the underway supply of seawater and hence phytoplankton detrital aggregates built up over a few days if it was not regularly flushed through. Science is never far away!

Overall the work was a success, certainly I got all I came for and more. Leaping rays, thresher sharks, dolphins and abundant turtles certainly make life at sea all the more wonderful. I look forward to my next venture out into the blue.

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