Baltic blooms

摘要

MESMERISING swirls etch a fleeting pattern into the surface of the Baltic Sea that shifts with the currents. This colourful assembly, off the coast of southeast Sweden, is made up of high concentrations of phytoplankton. They are most likely to be cyanobacteria, which behave like plants and capture and store solar energy through photosynthesis. Such phytoplankton blooms are more common in the summer, when plenty of sunlight is available at the water's surface. Blooms can span hundreds of square kilometres and last from a few days to several weeks, and no two are the same. Phytoplankton fares particularly well in the Baltic Sea because the water contains plenty of phosphate, an essential nutrient for growth.