And fewer diatoms…

The presence or absence of phytoplankton is not the only variable studied by Anne Goffart. «The composition of phytoplankton depends on the temperature of the water. When the water is cold, the diatoms are numerous. These are interesting components of phytoplankton because they have a higher nutritive value for the zooplankton. As they are relatively big, they tend to sink if they are not eaten. While singing they emit carbon-dioxide (CO₂) in the deeper layers. As the average winter temperature of the water increases, there are fewer diatoms in the water. This is another sign of modification and alteration» she explains. We are witnessing a double phenomenon: there are fewer phytoplankton and the proportion of diatoms present in the rest is diminishing. These results will also be used in simulations aiming to understand the implications for the zooplankton. The deeper we delve into the food-chain, the more difficult it is to untangle the web of cause and effect and the more difficult it becomes to find a connection with climate change. What is certain is that if the zooplankton is also changing, the rest of the food-chain ill follow suit. Beginning with the larvae of fish that feed on it, and which we know select their food according to mechanical criteria such as the size and shape of animals that form the zooplankton. If these details change, the larvae will have to adapt-but the question is-will they have time? Or will they disappear completely?

What is certain, according to Anne Goffart, and the most experienced divers of the STARESO station confirm this, is that the changes are visible to the naked eye: what can be seen in the water today is totally different to what could be seen thirty years ago! There are a lot more big fish, such as the barracuda, unknown in the bay of Calvi thirty years ago (but also because certain species are protected), a lot of thermophilic organisms arrived from the Eastern Mediterranean which is warmer and others which lived on the verge of the colder waters have disappeared. The limited appearance of certain types of phytoplankton containing very dangerous toxins due to favourable climatic elements can also be seen. She summarises, «It is obvious that if the changes happening to the phytoplankton can be clearly seen, then the implications for the food-chain become very complicated and we are in an unknown zone. What we do know for certain is that the changes are happening very quickly»