The 2017 Winter Cruise is looming, and the electricity can be felt in the air all the way in Stellenbosch. Researchers from Stellenbosch University (SU) and CSIR (Western Cape, South Africa) will brave the infamously rough seas of the Southern Ocean on board the SA Agulhas II, South Africa’s flagship vessel for innovative research, on her way from Cape Town to Antarctica. The team will be departing the Port of Cape Town on the 28 June 2017 and will be sailing along the newly proposed 30°E transect to the Antarctic ice. The new transect, and the fact that the SA Agulhas II will be solely used for scientific research on this cruise showcases the significance of the 2017 Winter expedition.
Oceans play a fundamental role in regulating the Earth’s climate through heat transfer and redistribution, oxygen production and CO2 storage. Tiny photosynthetic organisms known as phytoplankton are the drivers of these processes. These tiny marine plants are estimated to produce over half the oxygen that we, and all other land animals, breathe. Ocean waters have the capacity to absorb vast amounts of the greenhouse-warming gas, CO2. Indeed, nearly half the CO2 produced by human activities in the last 200 years has dissolved into the ocean. Phytoplankton have the ability to remove this dissolved fraction from the global CO2 inventory, thereby potentially lowering atmospheric CO2 concentrations. Understanding the factors governing this mechanism may improve our understanding of the oceans capability to cushion human-induced climate change.
The Southern Ocean (SO) connects three ocean basins – the Indian, Atlantic, and Pacific illustrating its importance to global ocean circulation and overturning. The SO is of particular significance to the global carbon cycle as up to 40% of anthropogenic CO2 passes through it. Of scientific interest, not just to our research group, but globally is what is known as the Southern Ocean paradox. The Southern Ocean is a High Nutrient-Low Chlorophyll (HNLC) region. This means it has high concentrations of macronutrients (nitrates, phosphates, silicates) which are essential for phytoplankton growth, but low chlorophyll – an indicator of phytoplankton productivity. So why the paradox? The reason for limited phytoplankton productivity lies in a scarcity of essential micronutrients/trace metals such as Iron and Zinc which are fundamental for photosynthesis.
During the 2017 Winter cruise our research group aims to collect data in order better understand; macronutrient distributions, trace metal speciation and distribution, plankton community and species-specific response to different trace metal additions as well as community structure and species distributions. We will be collecting water samples from various depths and latitudes for trace metal, macronutrient, pigment and isotopic analysis. Atmospheric dust from the SO will be sampled underway from a collector we have set up on the ships observational deck in order to shed some light on the composition of dust (a source of trace metals) transported to the SO. On-board incubation experiments will be conducted from seawater samples collected. These will be fertilized with sampled dust to study phytoplankton responses under trace metal additions. Pigments and biomarkers will be analysed to better understand the algal community structure and biomass distribution patterns in the Winter season. Lastly, bacterial communities will also be identified and their role with regard to trace metal cycling will be studied.
For the past two months the majority of our time has been spent on acquiring all the necessary equipment and, in our spare time, the therapeutic process of sample bottle cleaning and weightlifting. Over a period of two months we have relentlessly cleaned close to 2000 sample bottles and the joke among the group is that if our projects fail at least we have a bottle cleaning business to fall back on. The SU/CSIR ship team will consist of 11 members led by Dr Susanne Fietz. The bulk of the team is made up of Ph.D and M.Sc Earth Science students, with the addition of Jodi Pieterse from Biotechnology. For many of the researchers this will be their maiden Antarctic voyage, but hopefully the first of many to come. Andile Mkandla, a promising second year student, has been given an amazing opportunity to assist the team and will gain invaluable field and lab experience.
T-minus 5 days until departure! Final preparations are different for everyone, some are spending the bulk of their time at the pharmacy trying to figure out the cure for sea sickness, others are purchasing the last of their sub-zero clothing, while the “Antarctic cruise veterans” have been squeezing in their last few pints at the local bar prepping for a “dry” two and a half weeks at sea. Although preparations are different, the feeling of anticipation is both mutual and overwhelming for everyone. Follow our blog for more updates during the cruise!
Written by Ian Weir