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HomeFeaturesUnraveling the Mysteries of Harmful Algal Blooms in British Columbia’s Coastal Waters

Unraveling the Mysteries of Harmful Algal Blooms in British Columbia’s Coastal Waters

Phytoplankton, the microscopic organisms that inhabit the upper layers of the ocean, play a vital role in the marine ecosystem. Powered by photosynthesis, they convert sunlight and nutrients into organic matter, serving as the foundation of the oceanic food web.

From zooplankton to fish and marine mammals, numerous marine species rely on phytoplankton as their primary source of food. The abundance of phytoplankton is crucial for sustaining the health and balance of the marine ecosystem. However, not all phytoplankton species are beneficial. Some cause harmful algal blooms (HABs) that pose risks to both marine life and humans.


Harmful algal blooms occur when certain species of phytoplankton proliferate rapidly, causing a variety of issues. Some produce toxins that accumulate in shellfish, leading to poisoning when consumed by humans. Others release toxins that can be fatal to fish and marine mammals, while some species possess long spikes that can damage fish gills, ultimately causing suffocation.

Furthermore, dense blooms of any phytoplankton species can deplete oxygen levels, endangering aquatic life that relies on dissolved oxygen to survive. The frequency, intensity, and distribution of HABs have increased in recent decades, raising concern about their impacts on the marine environment.

British Columbia, with its rich coastal waters, is not immune to harmful algal blooms. In fact, BC has a unique historical connection to HABs, as the world’s first recorded scientific account of a harmful algal bloom occurred off its coast in 1793. Today, HABs in BC result in significant economic losses, leading to fish and shellfish mortalities and harvest closures.

Unfortunately, HABs are not currently recognized as an ecosystem stressor by Fisheries and Oceans Canada (DFO), which means there is limited systematic monitoring and research at the government level.

Recognizing the critical knowledge gap, the Pacific Salmon Foundation (PSF) has taken the initiative to study harmful algal blooms and their impacts.

As part of their Citizen Science Oceanography Program, the PSF has incorporated phytoplankton taxonomy studies. Through this program, over a thousand phytoplankton samples are collected and analyzed annually. This unprecedented monitoring effort has revealed that harmful algae are common and abundant in the Strait of Georgia, often reaching concentrations that negatively impact aquacultured shellfish and fish.

However, due to the lack of comprehensive ecosystem-based studies, the exact effects of these blooms on wildlife and the marine environment as a whole remain unclear.


Monitoring harmful algal blooms is essential for several reasons. It provides crucial information about their occurrence, patterns, and trends, allowing for the development of predictive models and early warning systems. Long-term data enables researchers to assess the impacts of HABs on various aspects of the marine ecosystem, including wild salmon stocks. Understanding the ecological consequences of HABs is vital for effective fisheries management, aquaculture practices, and safeguarding the well-being of marine life and humans who depend on these resources.

Moreover, monitoring HABs becomes even more crucial in the face of climate change. As climate change accelerates, its impacts on HAB dynamics are expected to intensify. By closely monitoring algae, scientists can better understand their triggers and work towards mitigating the proliferation of harmful algal blooms. Consistent monitoring also helps anticipate and prepare for future changes, enabling better adaptation to the impacts of climate change on coastal ecosystems.


The PSF Citizen Science Program has been instrumental in shedding light on harmful algal blooms in the Strait of Georgia. Through their extensive monitoring efforts, several harmful algae species have been studied. The program has learned several important lessons.

PSF Citizen Science map of patrols (Illustration: Ben Skinner and Island Fisherman)

For example, Alexandrium (which causes Paralytic Shellfish Poisoning) is very common in the Strait of Georgia, and its abundance is linked to large-scale climatic phenomena like the El Niño Southern Oscillation.

Microscopic view of Alexandrium, common in the Strait of Georgia. Photo by Svetlana Esenkulova

Dictyocha, another harmful algal genus, is abundant near river inputs and has been associated with liver damage in wild juvenile salmon.

Heterosigma akashiwo blooms (one of the primary causes of farmed salmon losses) have been linked to stratification, nutrient levels, and cloud cover.

Heterosigma akashiwo, one of the primary causes of farmed-salmon losses. Photo by Svetlana Esenkulova.

Noctiluca scintillans, while not directly harmful to salmon, occasionally blooms in the Strait and can disrupt marine food webs, affecting water quality and marine life.

Noctiluca bloom from the seaplane by Michael Bahrey

The PSF Citizen Science Program encourages coastal residents to contribute to HABs studies by reporting any unusual observations, collecting field notes, taking photos, and, if possible, collecting water samples.

Noctiluca bloom April 2018 by Ed Oldfield PSF Citizen Scientist

These contributions can help researchers analyze the samples and further monitor the health of coastal waters. The program aims to enhance public education and outreach efforts regarding HABs and promote food safety practices for shellfish consumers.

If you are interested in learning more about the PSF Citizen Science monitoring program and its research on harmful algal blooms, you can find more information in the following resources:

Harmful Algae and Oceanographic Conditions in the Strait of Georgia, Canada Based on Citizen Science Monitoring” (

Atlas of oceanographic conditions in the Strait of Georgia ( and updates on social media at

Words & Photography by SVETLANA ESENKULOVA, Biologist, Marine Science Program, Pacific Salmon Foundation

This article appeared in Island Fisherman magazine, never miss another issue—Subscribe today!








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