Last week during low tide I spotted some unfamiliar red clumps sitting on the exposed mud. So I sent a photo to our resident marine biologist, Michael Konrad on South Forty Dock, who identified them as red algae. He wrote back:
There are 3 major groups of algae, red, green, & brown. The clump in the picture looks like a red alga.
Algae get energy from the sun, as do plants, but algae do not have roots or veins, they don’t need them. Algae evolved on the earth more than a billion years ago. They are the ancestors of plants. Almost all multicellular organisms in the ocean that get energy from the sun are algae. As I mentioned in my eelgrass post, it is an exception, as they are really plants, and migrated back to the ocean.
Most algae that grow on the bottom around the floating homes have a dramatic growth pattern, they remain dormant as very small clumps or fragments that you don’t notice until conditions are good for their growth. Then they grow to the size you see in just a week or so and in some places almost cover the bottom. Exponential growth is powerful, as I said in my bacteria post. After a week or two or three the environment changes and they die back to their original levels where they are not visible to the eye. Life & death in the Bay.
According to Artificial Intelligence posts on the Internet, “some types of red algae are not fixed to the bottom, but grow as plankton, small clumps of cells that drift with the current. A harmful algal bloom (HAB), or rapid growth, can be dangerous to humans. While many red algae are not toxic, some species produce toxins that can cause various health problems.
HABs occur when algae, including some red algae, multiply rapidly, sometimes turning the water red (hence the term red tide).
Red tide is more common on the East Coast, particularly Florida. In California, we have a slightly different harmful alga the produces domoic acid. As AI puts it: “Domoic acid poisoning and red tides are related but distinct phenomena. Red tides are algal blooms, often discolored, that can produce toxins like domoic acid.”
Domoic acid is a neurotoxin produced by a phytoplankton, aka Pseudo-nitzschia australis. AI weighs in on the somewhat fuzzy distinction between plankton and algae: “Plankton is a general term for microscopic organisms that drift in aquatic environments, while algae are a diverse group of photosynthetic organisms, some of which are classified as phytoplankton. Phytoplankton are a specific type of plankton that are photosynthetic and form the base of the aquatic food web. Therefore, all phytoplankton are algae, but not all algae are phytoplankton.”
The Marine Mammal Center diagnosed the first case of domoic acid toxicosis in marine mammals back in 1998. It’s usually at tolerable levels in the ocean, but during plankton blooms there are more plankton in the water all producing the acid at once. When they are consumed by fish, the acid passes right through, and when the fish are eaten by predators the acid passes through to them as well. In sea lions and other marine mammals, domoic acid (or DA as it’s known at the Mammal Center) can cause seizures like epilepsy and if not treated in time, can attack the navigation center in their brains. Humans can get DA too, and the effect on us is called anemic shellfish poisoning.
CORRECTION
Michael passes along the following correction to his Floating Times post entitled The Greenhouse Effect.
In several places the phrase “Maxwell-Boltzmann” or “Boltzmann” is used. These should be replaced with “Planck black body.” These changes have been made in the Floating Times archives.