Alexandrium monilatum

Domain: Eukarya
Kingdom: Prostita
Phylum: Dinophyta
Class: Dinophyceae
Order: Gonyaulacales
Genus: Alexandrium
Species: monilatum

After spending some time talking about the horrors of invasive species, let me throw you a curve ball. We should all agree that invasive/nonnative species are harmful to us and the environments that they infiltrate. However, not all native species are good for their environment either.

How can organisms that are part of the natural balance of their environment be bad for it?

The simplest explanation I can give is this example. Our bodies need potassium to function properly, which we get from food like bananas. If our bodies don’t have enough potassium, then our muscles cramp and we can become stiff and sore. If we consume too much potassium, then it can poison and even kill us. Don’t worry, though; you would have to consume a truck load of bananas in a single day for that to happen.

Like our own bodies, environments need everything in moderation.

Alexandrium monilatum is a single-celled dinoflagellate found in the warm waters of the Atlantic Ocean, Gulf of Mexico, Caribbean Sea, parts of the Pacific Ocean, and the Chesapeake Bay. It is a special kind of bioluminescent algae; when agitated, the organism produces its own light in the form of a soft blue glow.

This dinoflagellate can reproduce sexually and asexually, meaning it can use its own genetic material to make copies of itself without the use of other individuals. It can also produce chains of individuals, ranging from 2 to 80 A. monilatum per strand.

A. monilatum uses photosynthesis to create its own food, making it a phototroph. It is preyed upon by small fish and filter feeders, making it part of the base of the food chain. So how can this armored alga be a bad thing? It sounds so productive, and it even glows blue at night when waves stirs the water!

The problem with A. monilatum is that it is considered a Harmful Algal Bloom (HAB) species. When conditions are right, this species will reproduce faster than it can be consumed by its predators, causing an algal bloom in the water. Blooms are large patches of algae that are seen by the naked eye, meaning there are millions of individuals concentrated in a single area.

Blooms are considered a problem because the water contains a finite amount of nutrients available to the algae. Once the supply runs out, it’ll take time to replace those needed nutrients. So these blooms are extremely productive for a short time, before the algae run out of food and die. When they die, they start to decompose. The process of decomposition takes up a lot of oxygen, and without the photosynthesizers there to replace the oxygen being used, the water becomes hypoxic—or worse, anoxic.

Once the amount of dissolved oxygen in the water is depleted, the area becomes a dead zone, and all the fish and other marine organisms either leave or suffocate in the water. Dead zones aren’t always permanent; however, they are still an inconvenience to the marine life and to us and should be prevented at all cost.

It is not my purpose to make Alexandrium monilatum out to be a bad guy, just to show that even native species can harm their environment under certain conditions. Algal blooms, or red tides, can be caused by a steep increase in important nutrients found in fertilizers, which enter the water as run-off from nearby farms, gardens, and agricultural facilities. A boom in available food causes a boom in creatures that depend on it, and that’s true no matter the species.

Bioluminescent algae are fascinating. I was lucky enough to swim at night in a lake full of a species of bioluminescent algae, though I’m uncertain what species it was. It was a magical experience that I will never forget, so I was excited to talk about A. monilatum and to discuss the importance of balance within an ecosystem.

Sources and more info:
https://naturalhistory2.si.edu/smsfp/IRLSpec/Alexan_monila.htm
https://www.chesapeakebay.net/discover/field-guide/entry/alexandrium_monilatum
https://www.vims.edu/bayinfo/habs/guide/alexandrium.php
https://www.vdh.virginia.gov/environmental-epidemiology/harmful-algal-blooms-habs/alexandrium-monilatum-hab-in-lower-york-lower-james-rivers-and-chesapeake-bay/frequently-asked-questions-faqs-alexandrium-monilatum/

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