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  • Amy Pilsbury


What are HABs? And how do they affect our marine environment?

Sargassum bloom, Mexico June 2020

Harmful Algal Bloom (HAB) is a term used to describe mass growth events of saltwater or freshwater algae. These can be either single celled micro-algae or larger macro-algae (seaweed!). Dependent on the species, they can have harmful effects on habitats, species and cause wider impacts to local economies.

Harmful algal blooms (Infographic:@amy_pilsbury)

Blooms occur all over the planet and are now seen appearing increasingly in areas they haven't been seen previously. They are influenced by changes in conditions such as nutrient influxes from external sources, such as upwelling or fertiliser runoff. Changes in pH and temperatures can also provide favourable conditions to spark growth of individual species. Climate change could cause a rise in the frequency of blooms.

Harmful blooms in the UK (Infographic: @amy_pilsbury)

Harmful blooms in the UK (Infographic: @amy_pilsbury)

Problems associated with HABs

Some bloom species can produce toxins which can kill shellfish, fish, mammals and birds. These can also cause toxic illnesses in humans after consumption of intoxicated seafood or drinking water. Closure of shellfish harvesting areas and fisheries are frequently seen in the UK due to toxin producing algal species which are monitored all year round. Other species can cause oxygen reductions and restrict photosynthesis in the water.

Macro-algal HABs can cause these issues too, but have added impacts once they wash ashore. Sargassum causes issues for coastal ecosystems, such as coral reefs, and has been seen smothering turtle nesting sites reducing populations. The seaweed can also accumulate marine plastics at sea and bring them ashore, again causing problems for local wildlife.

Often, large quantities of seaweed wash ashore in a single season. This biomass rots on the shoreline creating unpleasant areas for tourists to visit, causing huge declines in localised tourism economies and costing local governments millions of dollars in clear up costs.

What are we doing?

PhycoMExUK are focusing on developing solutions to the Sargasusm HAB which washes up on Mexico's Eastern coast every summer. In May 2020 alone, 8.7M tons hit the Mexico and Florida coastline! (although this is actually less than has been seen in previous years). We are using hydrothermal techniques to convert seaweed biomass into useful products, such as fertilisers and biofuels. The hope is that these techniques can be used globally on various harmful species to help alleviate some of the issues surrounding HABs in our oceans.

Stay tuned as we continue to find solutions to the Sargassum crisis in Mexico. Follow us at @PhycoMExUK and sign up for our monthly updates on our website

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