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I noticed that this summer we had lots of sun in Ventura and very little red tide and wondered if there is a connection? Has this been studied? Hello to all of you grad students.
Question Date: 2008-10-07
Answer 1:

Is it possible you were comparing the number of sunny days last summer to the previous winter? Instead, think about the nutrient loading and how that changes seasonally. I've never noticed the red tide here at all, but I can guess that it is probably much more prevalent in the winter.

Algae are photosynthetic, so limited sunlight could limit their growth and more sunlight (like you observed) could not be a limiting factor for the algae. However, southern California always has lots of sun so I highly doubt there is any correlation between algal blooms and sunlight here at all.

Algal blooms occur when there are increased nutrients in the water. The nutrient source can be natural (e.g. upwelling) or anthropogenic (e.g. dumping of wastewater). Southern California has lots of anthropogenic nutrients dumped in our oceans, so that's the likely culprit. During the winter, wastewater treatment plants and rivers can be overrun with all the nutrient-rich rain runoff and those extra nutrients are dumped in the ocean. Upwelling is also at a maximum during the winter along the California Bight, which can bring nutrients up to the surface and also help increase algal growth.

If you did mean last summer compared with the previous summer, then I'd still say there must have been some difference in nutrient loading between the two summers that caused a change in algal blooms. The first suspects I would consider for a change in nutrient loading are farms (were there changes in crops? changes in fertilizers?), wastewater treatment plants (were there any changes to where or when or how much treated water they released?) and construction (were any wetlands removed or altered? were concrete rivers restored to natural conditions?)

A lot of people do study related topics. I have had many peers who studied things like nutrients entering the ocean from wastewater treatment plants and how nutrients are effectively removed by wetlands. I don't think I know any biologists, but I'm sure they study things like how plant and animal life are affected by algal- covered anoxic waters.

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