What’s happening in your pond? – The recent algal blooms

When completing the VIP services this month it was duly noted that some clients had experienced an algal bloom in their ponds, which had until recently been as clear as they day we built them. Therefore it only seems appropriate to explain why these algal blooms can become apparent and how recent conditions have led to some ponds experiencing them.

Much like any plant, the three main factors regulating the growth of algae are nutrient levels, temperature and sunlight. Nutrients promote and support the growth of algae with the main contributors being phosphorus and nitrogen. Nitrogen and phosphorus are found in the landscape surrounding your pond or water feature as they are in high concentrations in the soil your garden is comprised of. These can then enter your pond or water feature through a process called ‘surface runoff’, which simply put, is where rain water carries particles of soil into your pond during periods of heavy rainfall. Thunderstorms are also a menace when looking at algae growth. It is well known that thunderstorms are accompanied with lightning. Lightning creates nitrogen in the atmosphere which is then added to your pond’s ecosystem through rain water, again feeding the algae’s growth and influencing the algal blooms.

Algal blooms usually occur when water temperatures are higher and there is increased light. Enjoying warmer temperatures explains why the growth of algae during this period is known as a ‘bloom’, as soon as temperatures decide to fall algae growth will stop persisting. Algae will photosynthesise in order to grow, just like any other plant. Increased light levels will provide the algae with more energy to utilise when growing, further assisting in the algae growing over such a short time period.

So how have recent conditions lent themselves to the algal blooms people have been experiencing? In the early weeks of June we experienced thunderstorms, followed by heavy periods of rain and then the warmest temperatures ever recorded in June! As a result, all of the optimum conditions needed for algae growth were recorded in the UK over the space of a week, hence why the algal blooms were so sudden.