Climate change and nutrient loading: recipe for harmful algal blooms in lakes

What is it about?

Microscopic algae or phytoplankton can cause harmful algal blooms (HAB) in lakes. This is mostly caused by increased nutrient pollution (or “eutrophication”). Climate change has increased HAB occurrences and nutrient pollution of lakes globally. Increasing global temperatures, precipitation, and nutrient addition due to human activities are the major causes of these events. Research so far has focused on the effects of nutrients or of climatic factors to understand the problem. However, this may paint only a partial picture. To understand the problem better, authors of a new study used statistical and modeling approaches. They studied the trends in phytoplankton bloom at Lake 227 in Canada. This lake has been the site of fertilization experiment for 48 years. The model used by the authors considered the effects of climatic factors and nutrient pollution to determine HAB drivers. It also replicated climatic conditions and lake physics over the duration of the experiment. The authors found that increasing water temperature during spring led to massive algal blooms. Additionally, HAB was much more pronounced under the effects of climate change than under nutrient pollution alone. Thus, it is important to not only reduce nutrient influx but also include climate factors when planning lake management strategies.

Featured Image

Photo by Claudia Chiavazza on Unsplash

Photo by Claudia Chiavazza on Unsplash

Why is it important?

When lake water becomes infested with algae, its water quality deteriorates and marine life is threatened. At present, research and management efforts focus on controlling the ratio of nitrogen and phosphorus in lakes, which are the two important polluting nutrients. But, to manage water bodies, it is necessary to understand the factors driving eutrophication as well as their interactions. This study helps to understand the effects of interacting factors like climate change, nutrient loading, seasonal changes, and competition among different phytoplankton. KEY TAKEAWAY: It is important to consider climatic factors when estimating future conditions in addition to controlling nutrient pollution to successfully manage lakes.