Sea sawdust, not chocolate milk

Turns out I was wrong about the chocolate milk.

It wasn’t churned up red drift algae, as I mistakenly posted …

but rather a Trichodesmium bloom.

Rhonda Watkins, a coastal and inland water quality specialist with Collier County government, has her fingertips on the pulse of our coastal waters — and quickly pointed me in the right direction:

The picture you have of the beach on May 10th and chocolate milk appearance you describe are not red drift algae, but rather from a Trichodesmium bloom–a marine blue green algae. You should have also noticed a sickening sweet odor associated with the bloom. Please visit the link to (Collier County’s) red tide updates which includes information on Trichodesmium.

Rhonda also mentioned that she is currently working with MOTE to add Trichodesmium blooms to their Daily Beach Report.

Rhonda also provided a photo what red drift algae really looks like when its washed up on shore. It’s is a macro-algae: you can pick up with your hands, and have to slog through it with your feet.

And yes, it can really smell bad. It’s definitely not a good place to lay out a towel.
Rhonda pointed me in direction of this Fish and Wildlife Research Institute link. It provides a brief and illuminating natural history of Trichodesmium. The post was written in 2004 when a similar coastal bloom occurred, and comments:

Trichodesmium blooms occur every year in the gulf, generally offshore in oligotrophic waters, but they can occasionally reach nearshore areas when currents and winds push an established offshore bloom to inshore areas.

It’s interesting how the pieces add together.
There was an incredibly stout on-shore breeze from the southwest. That’s probably what brought the bloom to the surf line. And thinking back to that trip to the beach, our 6-year old son cried out “red tide” immediately after exiting the car and getting a whiff of the air.
That was the “sickening sweet” odor that Rhonda mentioned.
Of course I couldn’t smell a thing.

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