Question: What are ways to monitor algae blooms?

There is a service I heard about on a TED talk at www.planet.com. Apparently they are using satellites to take daily pictures of the earth for comparison. There is also an API on there that you might be able to use for coding a system to compare the results from the daily photos. I don't know to much about that but this might be a place to start. Good luck.

Not sure if all algae blooms have the same red color but it looks like the ones in Florida peak at 700nm. See: https://hyspiri.jpl.nasa.gov/downloads/2016_Symposium/poster/1_Amin_HyspIRI_Symposium_2016_Poster_Ruhul.pdf An IR camera image would probably be washed out from the infrared in the sunlight. One experiment would be to remove the standard IR blocking filter in a color camera and replace with a filter that covers the deep red range to 720nm.

Filter would look something like:

https://www.semrock.com/FilterDetails.aspx?id=FF01-745/SP-25

The intense red tide blooms (Karenia brevis) in the Gulf of Mexico are easy to detect with normal color photography because they are red (top image). The green algal blooms (lower image) are also easy to detect when they are intense.

Detecting these blooms is not so easy when they are less intense, when the water is muddy, when more than one species is present, or in shallow water where the bottom reflectance alters the color. The link provided by @MaggPi suggests that an NDVI-like index based on the difference between reflectance at 662 nm and at 680 nm is effective for detecting red tide. Expensive narrow-pass filters and a two-camera system would be required to capture these photos yourself. Satellites take images at these wavelengths every day.

A DIY single-camera NDVI system could probably highlight intense blooms in clear water. To detect red tide, which reflects lots of red light because the dinoflagellates use more blue light for photosynthesis, a blue filter might work better (these cameras use blue light to represent the color of light absorbed by plants for photosynthesis). To detect a green algal bloom, a red filter might work better because red light is used by those cameras to represent the color of light absorbed by the plants.

Chris

Too bad the editor for Answers is still not working.

Other algal blooms can also release certain toxins into the water and the air causing a burning sensation in the lungs if inhaled.

Here a software oriented approach. The following open source sample in Python language was developed for the blue & golden dress challenge, its an 3D RGB Histogram. The color analysis helps to detect given patterns and separate color nuances and its distribution. You can apply this code to satellite and areal pictures. It might be a starting point for development of your own monitoring system. You find the source code at the following link: http://marksolters.com/programming/2015/02/27/rgb-histograph.html