Successful PhD defense today – Using machine learning to predict when and where harmful marine algae will occur

Edson Silva has been working towards obtaining his doctorate for the past three years, as part of the Climate Dynamics and Prediction Group at the Nansen Center. Today his degree is being awarded by the University of Bergen. Congratulations, Dr. Silva!

Algae are a crucial component in the marine ecosystem, but they can also harm it. Some microscopic algae can produce toxins which can be filtered by shellfish and reach high concentration levels. So, when humans consume those shellfish, they can get poisoned. Monitoring in shellfish farms makes it possible to avoid consumption of contaminated shellfish, but the economic loss can be significant as selling contaminated shellfish is banned. Being able to predict when toxic algae abundance rises to dangerous levels, so called “harmful algae bloom” (HAB), can help farmers to plan mitigation and refine the monitoring program to more accurately detect when and where a HAB can occur. This is the purpose of Silva’s PhD. He set out to develop methods for predicting HABs impacting shellfish farms in Norway.

Silva used machine learning techniques fed with environmental data from satellites and model reanalysis, as well as observations of toxic algae in shellfish farms (provided by the national monitoring program) to find out what the typical environmental conditions favourable for HABs are.

The models he developed can accurately predict the likelihood of the occurrence of HAB species monitored on the Norwegian shelf.  This can help to better plan locations of future farms to minimize loss, and to help improve the national HAB monitoring to refine measurements at times when they are most needed. Moreover, the models make it possible to be warned about the amounts of toxic algae from one up to four weeks ahead of time at specific aquaculture location. This can give shellfish farmers enough time to react and to prevent economic loss.

Silva focused his efforts on predicting algae blooms on the Norwegian shelf, but the models can be adjusted to be useful for any other location on Earth, making them a very useful tool to mitigate the damage HABs can cause. If you want to hear more about this new tool, you can listen to the episode of the Bjerknes Climate Podcast featuring Edson Silva here.

Silva has obtained a bachelor’s degree in oceanography at the Federal University of Paraná and a master’s degree in remote sensing at the National Institute for Space Research (INPE) in Brazil. He started his PhD in 2020, as a research fellow at the Nansen Center and a PhD candidate at the University of Bergen.

Supervisors and collaboration

Edson Silva (in the middle) has been supervised by François Counillon (left) and Julien Brajard (right, both Nansen Center), as well as by Noel Keenlyside (UiB & Nansen Center). Edson has been working with researchers at the Bjerknes Climate Prediction Unit and collaborated with researchers at the Centre for research-based innovation “Climate Futures”.


During his PhD, Silva published two papers, he has another one currently in review and another one in preparation.

His thesis, “Prediction of Harmful Algae Blooms Impacting Shellfish Farms in Norway”, can be found online.

Doctoral education

Most PhD candidates are part of a PhD program and can have their workplace either at a university, or at a research institute. We are hosting PhD candidates in different ways: through the allocation of funds by the Research Council of Norway for department PhDs, or project funding from various sources. When we employ PhD candidates, they are at the same time enrolled in a PhD program at a university or college, which is the institution granting the degree. Since we were founded 37 years ago, we have happily hosted 56 PhD candidates who defended their thesis as employees at the Nansen Center. This makes Dr. Edson Silva number 57 on the list!