A blog entry by Dr. Janet Cotter, scientist on board the Esperanza for the Arctic Under Pressure Expedition.

As the Esperanza leaves Ny Ålesund and Svalbard, the mesocosms are all set up and running, and our job delivering and assisting their placement is done. We'll return in just over one month’s time to retrieve the mesocosms from Kongsfjord and ship them to Germany. But that's not the end of the story, as the science part is only just beginning.

Whilst the mesocosms were being set up, more than 30 scientists arrived here from all over Europe, including the Netherlands, UK, Norway, France and Germany. Over the next few weeks, they'll be working hard, collecting scientific data that will be carefully examined and statistically analyzed during the following months, perhaps for even a year. Eventually, the results from the mesocosm experiments will be published in scientific journals. Only then can we begin to understand in more detail what the effects of ocean acidification from increased CO2 in the atmosphere might be in Arctic waters.

The Esperanza not only brought the mesocosms to Ny Ålesund, but also many boxes and crates of scientific equipment - all carefully labeled and sealed: their purpose completely unknown to most on board. However, it’s now become clear. The boxes probably contain enough equipment to furnish a small University chemistry department. Several boxes contain carefully packaged delicate analytical instruments, which will be used in the chemical analysis of the water samples from the mesocosms. Fortunately, none seem to have been damaged in transit and all have now been recalibrated for their new labs (analytical instruments do not like to be moved!). Other boxes contain the items needed to handle the samples: pipettes, beakers, measuring cylinders, volumetric flasks, filter papers, tweezers and lots of other basic lab items.

Stepping over some boxes, I made my way into the lab, where Andrea was hoping to finish off making up calibration standards for one of the analytical instruments before dinner. I watch a Svalbard reindeer slowly make it’s way across the village, munching on the little bits of grass and moss that are growing between the accommodation huts now the snow is receding. She commented that this was the lab with the best view, looking over the fjord towards the snowy mountains and glaciers. This was disputed by Kerstin, who is working in a different lab, one that overlooks the bay and has a list of whale sightings. The beluga whales haven’t arrived just yet, but she’s hoping to see one before they leave. I’m quite envious. Although our labs in the science unit are very good, the view from the windows can’t really compare to this!

Each box has been carefully labeled with what it contains and which lab it belongs to, but even so, sorting it all out and finding space to store all this equipment must be a major headache for the logistics coordinator in Ny-Ålesund.

Out in the cold waters of Kongsfjord, the nine mesocosms have each been acidified to reflect a range of possible future levels of CO2 in the atmosphere. The experiment aims to determine the chemical and biological differences between these mesocosms over the next month. 

Every day, probes will be lowered into each mesocosm to record conductivity, light penetration and several other background parameters. One type is a fluorescence probe that characterises the different types of phytoplankton (tiny plants and bacteria that get their energy from the sun via chlorophyll).

The spectrum of light changes as it passes through water and different groups of phytoplankton have evolved to make use of the changes in the quality and quantity of light with depth and turbidity. Each phytoplankton group has a distinct make-up of chlorophyll and other pigments. The fluorescence probe detects these different types of pigments, allowing the relative abundance of phytoplankton groups to be monitored. Used daily, this probe gives a rapid measure of how phytoplankton communities are changing with depth and time in each of the mesocosms.

Fine nets will be used to capture and count the different types of zooplankton (animal plankton), such as tiny crustaceans and pteropods, which in turn feed on the phytoplankton. Many types of plankton (both phyto and zoo) form hard shells of carbonate, and it is these organisms that are expected to be amongst the most sensitive to ocean acidification, as it may be harder to survive under acidified conditions. As plankton forms the bottom of the food chain, the concern is that if they are affected, then it could have knock-on effects up the entire ocean food web.

Alongside probe and net measurements, daily sea water samples from the mesocosms will be taken back to the lab in Ny-Ålesund, and subjected to intense biological and chemical analysis to determine the changes caused by the artificial acidification.

So what will the scientists measure in the lab? Well, first of all the warehouse that usually houses the forklift equipment for the harbour has been cleared out. This is where the samples will be filtered to separate the solids, which are predominantly plankton, but also some bacteria and dead cells and other detritus, from the seawater (containing dissolved salts). The samples are then split between the labs for the various analyses to detect changes between the mesocosms.

The seawater will be chemically analysed for constituents such as phosphate, nitrate (and nitrite), sulphate and silicate; the pH will be accurately measured, and of course, the carbonate (or alkalinity) and total CO2 concentrations. The solid residues left after filtering will be analysed for their carbon, nitrogen and phosphorus content. This analysis will help to build up a picture of the amount of nutrients taken up by plankton growth, and how much are remaining in the seawater, to help the scientists understand any changes seen in the biology within the mesocosms.

Biological analysis includes further characterisation of the types of phytoplankton present and how they are changing over time. Various methods can be used, ranging from traditional microscopes (accurate but very time consuming!) through to automated methods which give statistical descriptions of the overall structure of the plankton community. One such automated method is "flow cytometry", which involves shining a laser at individual samples and examining how the light is absorbed and scattered to distinguish between different pigments and cell sizes. This allows a picture to be created of the whole phytoplankton community.

Viruses infecting the plankton will also be studied, as it's possible that some plankton species become "stressed" and "unhealthy" as the seawater chemistry changes during acidification, and become more susceptible to viral infection. Certain trace gases such as di-methyl sulphide, naturally produced by some types of plankton and important in the formation of clouds in the atmosphere, will also be measured. If the plankton are less productive, then they may not produce as much of these trace gases and this could alter cloud formation and possibly even climate. It's a reminder of how interlinked earth systems are - that even the smallest organisms can have an important role to play in much larger scale processes.

There are many other types of analyses being conducted at Ny-Ålesund, including sophisticated stable isotope measurements that track the passage of carbon from seawater as it enters the food chain. All of these analyses will be pulled together to build a picture of the biological and chemical changes going on in the mesocosms - eventually, when published, the results will shed light on what might happen to these sensitive ecosystems in the future, as they are become increasingly affected by ocean acidification.

These scientists have a lot of hard work ahead of them, but the experiments being performed here are of vital importance. So, we wish them lots of luck with the weather while we are away - at least they are not short of daylight!

- Janet Cotter

>>Find out more about the Arctic Under Pressure Expedition.