Algal blooms at the Dutch coastlines

This morning, radio and television spoke of red slurry covering the Dutch beaches around Scheveningen and Wassenaar, warning people not to enter the water. Working with algae blooms on daily basis, “red tides” are the first thing that springs to mind when hearing such news. Yet, I have to admit this was the first time that I heard of a red tide on the Dutch coast line.

Some further investigation into the topic, proved that blooming of harmful algae in the Dutch sea happens annually. The algae that are blooming this year, go by the name “Sea Sparkle” which they thank to the fact that it exhibits bio luminescence when disturbed. This can give pretty images at night, when the waves of the sea light up. Sea Sparkle, also known as Noctiluca scintillans is a dinoflagellate, which fortunately does not produce toxins. However, as these algae types typically feed on other types of phytoplankton, they can excrete quite high levels of Ammonium.

Although Sea Sparkle appears to be quite harmless, looking into the history of algae blooms in the North sea, many other algae blooms occurring in the North Sea can be toxic. The dinoflagellate Alexandrium spp. for example, was first observed in the North sea in 1989 and can produce a toxin. In other countries Red Tides can create serious issues, such as massive fish kill and various kinds of shellfish poising. 

Worldwide, the occurrence of red tides and other harmful toxic algae blooms in coastlines is increasing. Accountable factors for this, are unfortunately almost all caused by human actions, such as:

• Eutrophication: The increase of nutrients (N and P) in the water, mainly due to pollution from rivers and inland water flowing into the sea.
• Cross Contamination from for example, aquaculture and the release of ballast water from ships.
• Disturbed nutrient balance due to over fishing.
• Global climate change

This all gives rise to the thought, that even though many initiatives are taken to reduce pollution in our freshwater, rivers and channels, we are still not doing enough to reduce the inflow of nutrients into our waterways and finally, into the sea. While it is necessary to achieve a 50% reduction in river load of nitrogen and phosphorus (compared to levels in 1985), research from “het Planbureau voor de Leefomgeving (PBL)” in 2011 states we are not on track yet. Improvement in nutrient loading of rivers, lakes and streams has apparently stagnated over the last decade in many water bodies.

On a positive note, nutrient loading in the larger rivers is still improving, however their water quality is mainly influenced abroad. Hence, we may ask ourselves, are we currently doing enough to effectively reduce our nutrient streams into the ocean, or will we see more of these events in the future?