This blue-green mat to the right in the photo is mostly cyanobacteria, with some diatoms and some other bacteria I dont know about anymore. I learned about this 20 years ago so I might be a bit rusty.. They use a mucus to stick to everything/everyone else and make these thick, slick mats. This one is probably a mm thick, but they get much thicker and sort of rubbery. Like when you leave the ketchup open too long and it skins over. Ive seen a few about 1-1/2 cm thick or so. The top drys out a bit, and cracks, but the underneath is still gooey and disgusting.
Notice how there are human footprints in or around it, along with what I assume are dog tracks. My knowledge of bacteria is pretty rusty but I do know that quite a bit of cyanobacteria is extremely toxic. It attacks the liver, and can kill dogs as well. Flesh eating Vibrio also thrives in the back waters that feed this exact estuary. A man fished nearby here and ended up in the hospital and later died. And some dumbass was walking through it, with their dog i suppose.
I think very small crabs and snails that can tolerate this stuff end up inside it or under it depending on how thick it is, and can live off of it. Then birds go after the crabs and snails. When the bacteria dry up and die off they fix carbon, nitrogen and other nutrients into the soil, which allows stuff like pickleweed, and saltwort, and a whole mess of other salt tolerant plants to grow.
I included another photo just because. The sun was setting, and it was setting in the direction I was taking photos, so it reflected pretty heavily off the water so its hard to see exactly how green and gooey it was. Sorry. Im standing on a walkway here and there are signs asking not to go walking off into the grasses so this was the best shot I could work up in the time I was there.
