Zooplankton in a Changing Climate – A Key to Healthy Oceans
Prof. Dr Maarten Boersma, Interim Director, Head of AWI Helgoland and AWI Sylt and Professor at the University of Bremen.
Zooplankton
Coastal research
Coastal seas such as the North Sea are truly multi-talented: they provide energy, secure jobs, enable trade and attract millions of tourists every year. However, economic exploitation comes at a price - and the state of the sea is a growing cause for concern.
The North Sea is one of the most intensively utilised marine areas in Europe. Fishing has been practised here for centuries. It is now home to huge offshore wind farms, which play a key role in the energy transition. The region is also an important transport hub: the major ports in Rotterdam, Hamburg and Antwerp make the North Sea one of the busiest waterways in the world. But with shipping traffic comes pollution. Ballast water, noise, pollutants and the risk of oil spills are a burden on the environment. However, it is not only human use but also climate change that is causing problems for the North Sea. Rising sea levels, more frequent storm surges and coastal erosion threaten nature and settlements alike. The Wadden Sea - one of Europe's most species-rich but also most vulnerable ecosystems - is particularly vulnerable.
In addition to the visible problems, research is now also focussing on less obvious connections - such as plankton. These tiny organisms are inconspicuous but crucial: they are at the beginning of the food chain, produce organic matter with the help of sunlight and form the basis for all life in the sea. Changes in nutrient levels in the water caused by climate change can impair the quality of plankton food. As a result, zooplankton, which feed on phytoplankton, grow more slowly or suffer from deficiency symptoms despite an abundance of food. This in turn affects fish and other marine life that rely on plankton as a food source.
Ecological stoichiometry is a research approach that has so far mainly been known in specialist circles. It analyses how the ratio of chemical elements such as carbon, nitrogen and phosphorus influences the interaction of organisms. It is not only the quantity of nutrients that counts, but also their ratio to each other. Eutrophication in particular, i.e. the over-fertilisation of water bodies due to agricultural inputs, can disrupt these sensitive balances and trigger a chain reaction in the ecosystem. In order to recognise such developments early on, a better understanding of the nutrient requirements of key organisms such as plankton is essential.
The North Sea shows how closely the environment, economy and science are linked - and how important it is not to lose sight of ecological connections. After all, what starts with tiny plankton can ultimately have far-reaching consequences for humans and the sea.
