Bloomin’ Climate Change and Its Effect on Plankton

BY ALLY HUGHES

Phytoplankton are colorful microscopic organisms that sustain all marine life, and a lot of life on the ground too. They are the lungs of the ocean, and responsible for 70% of the oxygen we breath! They are the primary producers of the ocean, they use our unwanted (and very harmful) carbon dioxide to produce vital nutrients. Every spring, blooms of phytoplankton appear in oceans around the world that coincides with the hatching of fish larvae who need lots of food and nutrients to make it to adulthood. As you can imagine, these natural blooms are really important for the survival of the ecosystem, however in recent years we have seen an increase in harmful algal blooms which are blooms of toxic phytoplankton caused primarily by climate change. These blooms come with the release of nasty toxins which cause shellfish poisoning and have been responsible for the deaths of some dogs in recent years that have visited or drank from contaminated water. 

Climate change is causing an increase in carbon dioxide in the oceans, and phytoplankton love carbon dioxide. The rising temperature in the oceans also causes them to get hot and bothered in the same we do during these hellish heatwaves. And finally, excess rainfall and natural disasters is washing a lot of agricultural waste into the oceans which are rich in nitrogen and phosphorous, two other nutrients that phytoplankton need in order to grow. The combination of these factors, and some other complex phenomena, are leading to humongous summer blooms in the oceans and in freshwater lakes of harmful phytoplankton. Some are so large, they can even be seen from space!

Photo credit: USGS/NASA Earth Observatory

The rapid change in our climate is having a profound impact on our oceans. It is expected that these spring blooms will slowly shift to become autumn blooms by the end of the century which will wreak havoc on the life cycle of many marine fish that depend on these spring blooms to support the survival of their young. However it isn’t all doom and gloom when it comes to phytoplankton and climate change. Some phytoplankton species, such as Chlorella and Spirulina (Arthrospira), have great health benefits for humans and are being produced by the tonne around the world. The great thing about this is that these species need carbon dioxide to grow! So increasing our production of these “good” phytoplankton species will actually help us reduce the amount of carbon dioxide in the atmosphere and have a positive effect on climate change!