A focus of the ongoing oyster experiments across the south coast is calculating the amount of nitrogen the oysters are removing from coastal waters and harbours. To do this we have been collecting our oysters from each of the different experiments in Langstone Harbour, the River Hamble and Poole Harbour every 2 months since the beginning of the project.
Once back at the lab the fun starts, the oysters are measured and weighed to keep track of how much they have grown and assess their condition, and then with a careful and steady hand each oyster is shucked to reveal the tissue inside but unfortunately, these are not for eating! The oyster tissue is scraped from the shell of each oyster and weights are recorded for both the empty shell and the tissue, from there we use an impressive piece of kit called a lyophiliser to freeze dry the tissue samples.
The lyophiliser creates a powerful vacuum that is close to that of the vacuum of space and keeps the samples at -100°C! This removes all of the moisture from the oyster tissue via a process called ablation where ice turns straight into water vapour missing out the liquid stage. After undergoing this process, the team can analyse the amount of nitrogen that is present in the tissue samples.
Getting to use complex machinery like this is one of the aspects of the project that the team here at University of Portsmouth really enjoy about Project RaNTrans.