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iLabs: OUR Dinoflagellates vs. the Ones For Red Tide

August 11, 2012

We recently shared an update on our biolumininescence activity in the Micro World — the exhibit we are creating using the bioluminescent dinoflagellate, Pyrocystis fusiformis. This exhibit will allow visitors to view the blue light flashes these organisms give off when disturbed.

A visitor, upon hearing our creatures were dinoflagellates, asked if these were the same ones responsible for Red Tide. Red Tide is caused by marine algae known as phytoplankton, specifically, dinoflagellates.

The short answer to her question is “not exactly.”  But to further understand this answer, let’s take a deeper look at what Red Tide is, and what Pyrocystis isn’t.

Red Tide used to refer to one causative organism, Karenia brevis, or Florida Red Tide,  but has since broadened to include a variety of causative organisms. From Wikipedia:

“Red tide is a colloquial term used to refer to one of a variety of natural phenomena known as a harmful algal blooms or HABs. The term red tide specifically refers to blooms of a species of dinoflagellate known as Karenia brevis.[10] It is sometimes used to refer more broadly to other types of algal blooms as well.

The term red tide is being phased out among researchers for the following reasons:

  1. Red tides are not necessarily red and many have no discoloration at all.
  2. They are unrelated to movements of the tides.
  3. The term is imprecisely used to refer to a wide variety of algal species that are known as bloom-formers.”

As a technical term it is being replaced in favour of more precise terminology including the generic term harmful algal bloom for harmful species, and algal bloom for non-harmful species.”

So if you ask, is Pyrocystis fusiformis one of the dinoflagellates that causes an algal bloom, the answer is “Yes.” But its bloom causes the water to glow at night with bioluminescent light. It is to the best of my knowledge, not implicated in HARMFUL algal blooms. Examples of its bloom causing bioluminescence can be seen in several marine bays around the world, including three in Puerto Rico (from the American Museum of Natural History Blog entry: The Effects of DEET on the Bioluminescent Dinoflagellate, Pyrocystis fusiformis)

“Of the seven bioluminescent bays in the world, there are three in Puerto Rico: one in Vieques called Mosquito Bay, one in the southwest called La Parguera, and one outside Fajardo called La Laguna Grande. Each of these bays is filled with high concentrations of bioluminescent dinoflagellates, unicellular algae of the kingdom Protista. These microorganisms are autotrophic and produce their own energy through photosynthesis. What is most unique about them is that they use part of this energy to emit a bright flash of light whenever they are disturbed. They will bioluminesce only during the dark part of their circadian rhythm, and only when disturbed. Therefore, in naturally occurring concentrations, the bioluminescence can only be observed at night.”

On the other hand, some examples of organisms causing the HARMFUL algal bloom are:

1) The organism of the Northeastern US and Canada, known as the cause of Paralytic Shellfish Poisoning (PSP), is Alexandrium fundyense.

2) In Virginia, Cochlodinium polykrikoides, a single-celled marine dinoflagellate, is being monitored by the Virginia Institute of Marine Sciences (VIMS) as a cause of harmful algal blooms.  (From the VIMS website: VIMS researchers monitor “red tides” in local waters)

In fact to see some aerial photos of the extent of the algae bloom around August 1st and later, go to their website report.

3) Here in North Carolina, Pfiesteria has especially been a problem implicated in fish kills.

Historically, Red Tides have been noted even back in the 1600s by Gulf of Mexico explorers, and some seem to occur naturally. There is the question, though, of whether man’s activities may be playing a role in frequency and intensity of these events as noted in this Wikipedia entry:

“The occurrence of red tides in some locations appear to be entirely natural (algal blooms are a seasonal occurrence resulting from coastal upwelling, a natural result of the movement of certain ocean currents)[12][13] while in others they appear to be a result of increased nutrient loading from human activities.[14] The growth of marine phytoplankton is generally limited by the availability of nitrates and phosphates, which can be abundant in agricultural run-off as well as coastal upwelling zones. Coastal water pollution produced by humans and systematic increase in sea water temperature have also been implicated as contributing factors in red tides.”

So after this brief overview of Red Tides, algal blooms, our dinoflagellates (Pyrocystis fusiformis), and the dinoflagellates involved in HARMFUL algal blooms, my answer to the visitor’s question is that ours bioluminesce. Others cause toxic problems and disease.

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