Stunning satellite photos reveal - often harmful blooms of phytoplankton have not only been expanding - but intensifying significantly in the world’s coastal waters this century.

Canada is not immune.

by Larry Powell

Intensifying phytoplankton blooms off 

the coasts of BC and Washington State, 2006.

Credit: Lian Feng

After pouring over almost 800 thousand NASA satellite images taken over almost two decades, a team of Chinese researchers has generated a map which paints perhaps the clearest picture yet of the extent of these blooms - organisms that can be agents of either good or ill. 

Their findings have just been published in the journal, Nature.

Dr. Lian Feng of the Southern University of Science in Shenzhen, China and colleagues discovered, phytoplankton were affecting 8.6% of the entire global ocean area in 2020 -  a stunning expanse of 31.47 million km2. That was an increase of 13.2%, or 3.97 million km2 from 2003.

They found algal blooms in 126 out of the 153 coastal countries examined. Globally, both the size and frequency of blooms increased significantly over the study period,

Phytoplankton are families of microscopic algae. Their blooms heave been accumulating in the surface layers of both marine and freshwater ecosystems of the planet for a long time. They include (but are not limited to) the well-known cyanobacteria, often called “blue-green algae” which have also severely clogged freshwater systems such as Lake Erie and Lake Winnipeg for years.

To quote the report, “Many algal blooms are beneficial, fixing carbon at the base of the food chain and supporting fisheries and ecosystems worldwide. However, proliferations of algae that cause harm have become a major environmental problem worldwide. For instance, the toxins produced by some algal species can accumulate in the food web, causing closures of fisheries as well as illness or mortality of marine species and humans. In other cases, the decay of a dense algal bloom can deplete oxygen in bottom waters, forming anoxic ‘dead zones’ that can cause fish and invertebrate die-offs…with serious consequences for the well-being of coastal communities." 

Unfortunately, algal bloom frequency and distribution are projected to increase with future climate change…causing adverse effects on aquatic ecosystems, fisheries and coastal resources.

The team also found that increases in sea surface temperature - due to manmade climate change - can “significantly and positively stimulate bloom occurrence.”

Intensifying phytoplankton blooms off 

the Alaskan coast.

Credit: Lian Feng

In an email, Dr. Feng tells PinP,“Blooms were also found in the Alaska Current system, stimulated by the increase in sea surface temperature over the past two decades.” That system includes the waters around Haida Gwaii, also in BC coastal waters, to the north of Vancouver Island. 

The researchers hope their findings “can aid the development of strategies to minimize the occurrence or consequences of harmful blooms.”


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