Ecofacts: Seaweed – Too Much of a Good Thing

Seaweed is algae, and is, as with so many things, necessary and all good. Until there’s too much of it. As home and food for myriad creatures, as a CO2 sink and as an ecosystem filter, it consumes great quantities of nitrates,… ammonia, phosphates and metals, thereby filtering the water of elements that are undesirable for other life forms. It performs many valuable functions.

If there is too much “nutrient loading” of coastal waters from agriculture (fertilizers,) human and animal waste (livestock production, fish farming or aquaculture, sewage treatment), urban runoff and industrial effluents, the algae proliferates – blooms. This then has some very undesirable effects. The bloom dies and is eaten by bacteria which suck the oxygen out of the water, suffocating creatures.

The blooms cover the surface and block sunlight from reaching the algae/seaweeds below, and some of the algae themselves are toxic to fish, marine birds. mammals and humans. Extreme versions of this are the dead zones which exist in coastal waters around the globe, large swaths of waters where there is almost no life. The second largest is in the Gulf of Mexico, now the size of Connecticut.

Algal blooms happen in brackish and freshwater bodies too. Just last week, a bloom in Lake Erie kept more than 400,000 people from being able to drink the water in their homes.

Here in Santa Barbara, our Bird Refuge becomes not a good one at all at times, reddish and smelly, and when the “red tide” happens on our coast it is a downright creepy place to be. Algal blooms may be natural, but for their frequency, size and intensity, you can thank us. One good note here, the zone in the Gulf is now two thirds the size it was 14 years ago.


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Algae Asia News

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