Spring has sprung, and blooming isn’t just for flowers. This time of the year, coastal areas are experiencing a bloom in algae production. While a ‘greener’ world is beneficial, high algal production can be quite deleterious to its environment, leading to events known as harmful algal blooms (HABs). HABs are dense accumulations of microscopic algae, also known as phytoplankton, which overproduce by synthesizing in sun-lit coastal surface waters. But what exactly are phytoplankton, and how can such a small organism be harmful?
Phytoplankton are the plant-like members of the microscopic plankton community, which form the foundation of the entire marine food web [1]. They photosynthesize food for themselves using chlorophyll (the component that makes plants and algae green), carbon dioxide, water and sunlight. Chlorophyll-a, a specific type of chlorophyll, directly indicates phytoplankton abundance, as shown in this week’s Map of the Week, and is used to monitor algal population growth.
In spring, as sunlight increases and seawater warms, it creates an ideal environment for algae to thrive, and they begin to ‘bloom’. Phytoplankton are responsible for half of the world’s oxygen. Thanks notably to phytoplankton, the ocean is an important carbon sink, helping to reduce atmospheric carbon dioxide levels. However, excessive phytoplankton can be detrimental [2]. HABs pose serious risks to ecosystems and human health, creating ‘dead zones’. When phytoplankton populations die after their spring bloom, their decomposition depletes oxygen, leading to deoxygenated environments and mass fish deaths. These HAB events are becoming more frequent due to climate change and warming coastal waters.
The Marine Strategy Framework Directive (MSFD) Descriptor 5 addresses the causes of HABs and aims to protect marine environments by achieving Good Environmental Status (GES) of European Union (EU) marine waters [3]. This includes measures to prevent and reduce pollution.
For more information on phytoplankton, harmful algal blooms, and EU initiatives, check out the links below:
- IOC Harmful Algal Bloom Programme: This program helps Member States develop research and management capacity to understand, predict, and mitigate the effects of harmful algal blooms;
- Plankton & Plankton in the Baltic Sea: These resources provide detailed information on the diverse plankton, including their ecological roles and seasonal abundance;
- Phenomer, Phytoplankton Citizen Science: Phenomer is a European Commission-funded citizen science initiative that monitors marine water discolorations caused by phytoplankton blooms, contributing valuable data for scientific research.
- OceanICU: OceanICU is a project funded by Horizon Europe that seeks to gain a new understanding of the biological carbon pump, a natural process that sequesters carbon in the deep ocean and of which Phytoplankton are a crucial component. To learn more about how phytoplankton is helping us improve how we model and predict the biological carbon pump read the blog by Dr. Sophie Clayton.
This map layer is a product of Copernicus Marine Services.
[1] https://education.nationalgeographic.org/resource/plankton/