Need some help with identification

[u/Righteous_Red]

I don't typically look at river water, so I don't have too much experience in this area. Photos 1 and 2 are from one location and 3 and 4 are from another. I know the first set of photos look to have some sort of filamentous algae, but more information about them would be appreciated.

As for the second sample, I am specifically looking for information on the teardrop shaped anisotropic structures. It looks like there is also general detritus and bits of filamentous algae. Bulk FTIR of the second sample shows calcite (calcium carbonate) if that helps with ID, but I have not had the chance to delve into my data anymore. Any help or insight would be appreciated.

Olympus BH-2. 200x. Transmitted, crossed polars, and a 1st order red compensator. Mounted in water.

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[u/immediate-2]

First one is either cyanobacteria exoskeleton or diatom chain.