What's making the water yellow in Kasitsna Bay?

Observation by Mike Brubaker:

Crossing Kachemak Bay today I noticed areas of coloration in the water starting south of Hesketh Islands and again in Kasitsna. We have also had pollen events that look similar, but usually this is with spruce pollen in the spring. This is quite yellow in color. Algale, pollen, something else maybe?

LEO Network says:

Previous posts about algal blooms in the area have included non-harmful blooms from Mesodinium rubrum. This post was forwarded to the Kasitna Bay Marine Lab for consultation.

Comment from Kris Holdreid:

Thanks for the report! We also saw some of that yellow discoloration and debris in the water when we were at Kasitsna Bay Lab - it looked like it came from land, pollen or other, and we didn't sample it. There was quite a bit in the water after the high tide, which is also consistent with it coming from land. Separately we saw a relatively small area of red discoloration just outside Tutka Bay when coming out of there on Thursday afternoon. It looked just like a Mesodinium rubrum bloom (not toxic, but causes the water to turn red). We tried sampling with a bucket, but it was too far below the surface to catch with the surface bucket and we didn't have our Niskin bottle with us (that one lets us get subsurface samples). Interestingly, you will see red water from Mesodinium rubrum in a whole water sample, but if we filter it with our normal 20 micrometer phytoplankton nets we don't see it in the filtered water, because it is smaller than that mesh size. I've copied Dominic Hondolero here too, for any additional information he may have, since he is our phytoplankton expert. Thanks, Kris