From prokarytes to fish, a remarkable variety of marine life depends on bioluminescence (the chemical generation of light) for finding food, attracting mates and evading predators, and in large numbers, one of the most remarkable sights in the oceans are the bioluminescent trails of dinoflaggelates - like something magical out of a fairytale!
What is bioluminescence?
Bioluminescence is light produced or emitted by organisms through biochemical reactions, which acts as an alarm system when the organism is excited, disturbed or stimulated, with other uses including communications to other members of the species, to evade or warn predators and lure in prey.
Bioluminescence is usually a blue greenish cold light – most marine organism are sensitive to mainly or only to light near the blue spectrum. Around 80% of marine animals living in the deep waters of about 200m to 1000m possess a form of bioluminescence, with the most remarkable bioluminescent aquatic creature being jellyfish. About 50% of jellyfish are bioluminescent and there are over 80 different species of bioluminescent jellyfish in oceans around the world.
“Around 80% of marine animals living in the deep waters of about 200 m to 1000 m possess a form of bioluminescence”
The most abundant form of bioluminescence in the oceans are dinoflaggelates, a group of single-celled eukaryotes that are usually considered algae. Dinoflagellates are mostly marine phenomena, but they also are common in freshwater habitats. Dinoflaggelates can bloom in concentrations of more than a million cells per millilitre, and under such circumstances, they can produce dinotoxins in quantities capable of killing fish and accumulating in filter feeders such as shellfish, which in turn are a hazard to people who eat them. This phenomenon is called a red tide, from the color the bloom imparts to the water.
What are Dinoflagellates?
Dinoflagellates are a group of single-celled eukaryotes, phytoplankton, and are usually considered algae. The term “dinoflagellate” is a combination of the Greek dinos and the Latin flagellum. Dinos means “whirling” and signifies the distinctive way in which dinoflagellates were observed to swim. Flagellum means “whip” and this refers to their flagella. Dinoflagellate populations vary with sea surface temperature, Ph, salinity, and depth. Current estimates suggest a total of 2000+ living dinoflagellate species, which includes marine, freshwater, and parasitic dinoflagellates.
A rapid accumulation of certain dinoflagellates can result in a visible red coloration of the water, known as red tide (a harmful algal bloom), which can cause shellfish poisoning if humans eat contaminated shellfish. Despite being small, dinoflagellates are very resilient. When their environmental conditions get too tough, they can form tough little cysts that can survive in the sediment of their water as fossils for as long as 100 years. Once conditions improve, the dinoflagellates can reanimate. This makes it difficult to track their history as they can transform from noncyst to cyst formation multiple times.
“latest estimates suggest a total of 2000+ living dinoflagellate species, which includes marine, freshwater, and parasitic dinoflagellates”
Dinoflagellates claim their seat both in Zoology and Botany as they have chlorophyll which is the characteristic of plants. In the discipline of Zoology, they find their place in Phylum Protozoa. However, recently they have been assigned to an independent Phylum status. Although now classified as eukaryotes, the dinoflagellate nuclei lack some key features of eukaryotic nuclei and the group contains many complex organelles and lifestyles.
Some have structures similar to vertebrate eyes; some have nematocysts; some live as plasmodia (multinucleate forms); some have two flagella; photosynthetic dinoflagellates contain a bewildering array of plastid types; and the whole of their genetics and cell biology is, to put it mildly, eccentric. Ultimately, they are also part of a group called phytoplankton, ie plankton that photosynthesize during the daytime (like plants) to get their energy or “food”, which they use to produce bioluminescence at night. Phytoplankton are a vital part of earth’s fundamental processes as they produce up to 50% of the planet’s oxygen.
Dinoflagellates sometimes bloom in concentrations of more than a million cells per millilitre. Under such circumstances, a ‘Red Tide’, they can produce dinotoxins in quantities capable of killing fish and accumulating in filter feeders such as shellfish, which in turn may be passed on to people who eat them.
This phenomenon is called a red tide, from the color the bloom imparts to the water. Some colorless dinoflagellates may also form toxic blooms, such as Pfiesteria. A red tide occurs because dinoflagellates are able to reproduce rapidly and copiously as a result of the abundant nutrients in the water.
Although the resulting red waves are an interesting visual phenomenon, they contain toxins that not only affect all marine life in the ocean, but the people who consume them, as well. A specific carrier is shellfish. This can introduce both nonfatal and fatal illnesses. One such poison is saxitoxin, a powerful paralytic neurotoxin. Human inputs of phosphate further encourage these red tides, and strong interest exists in learning more about dinoflagellates, from both medical and economic perspectives.
“Dinoflagellates sometimes bloom in concentrations of more than a million cells per millilitre. Under such circumstances, a ‘Red Tide’, they can produce dinotoxins in quantities capable of killing fish and accumulating in filter feeders such as shellfish, which in turn may be passed on to people who eat them”
For something so small, some dinoflagellates do emit remarkable visual traits. When the water around them is disturbed, certain types of dinoflagellates will emit a bright, blue light – an action which is either believed to be designed to confuse any prey nearby, or to attract other, larger organisms that are further up the food chain to the area, thus potentially eating what is threatening the dinoflagellates. The other possible cause being to ward off potential predators by an indirect effect such as the “burglar alarm”. More than 18 genera of dinoflagellates are bioluminescent, and the majority of them emit a blue-green light. The luminescence occurs as a brief (0.1 sec) blue flash (max 476 nm) when stimulated, usually by mechanical disturbance. Therefore, when mechanically stimulated – by boat, swimming, or waves, for example – a blue sparkling light can be seen emanating from the sea surface.
Bioluminescent dinoflagellate ecosystem bays are among the rarest and most fragile, with the most famous ones being the Bioluminescent Bay in La Parguera, Lajas, Puerto Rico; Mosquito Bay in Vieques, Puerto Rico; and Las Cabezas de San Juan Reserva Natural Fajardo, Puerto Rico. There are also bioluminescent lagoons near Montego Bay, Jamaica, and bioluminescent harbors surround Castine, Maine. In the United States, the Indian River Lagoon in Florida is abundant with dinoflagellates in summer.
Dinoflaggelate bioluminescence even has its place in military history. In November 1918, toward the end of the Great War, a British ship gliding on the surface of the ocean, off the coast of Spain, noticed a strange shape down in the water. It was blue, glowing, and suspiciously large. The ship attacked. The hunch that the sailors had found something suspicious was correct: they had destroyed a German submarine that had agitated a field of bioluminescent plankton, which lit up and gave away its position. Sailors had long noticed the transcendent light of “milky seas,” where glowing plankton gathered en masse and lit the water up. The Arabian Sea was known to glow, as were the seas around parts of Indonesia.
Detect dinoflagellate bioluminescence with Glowtracka
Chelsea Technologies’ GlowTracka detects bioluminescence from dinoflagellates and similar organisms. Originally developed by Plymouth Marine Laboratory in the UK, GlowTracka’s precision flow meter stimulates bioluminescent organisms and measures the light flashes as the organisms pass the detector, giving photon level sensitivity.
GlowTracka is highly flexible in its deployment options, including moorings, profiling (with pumped system) or deployment in towed vehicles.
Study Phytoplankton with LabSTAF
Chelsea Technologies’ LabSTAF is the world’s leading instrumentation option for studying Phytoplankton and Harmful Algal Blooms.
- Analysis of the biochemistry and ecology of aquatic systems
- Verification of satellite data
- Facilitates measurement at scales from mesoscale eddies to oceanic fronts
- Climate change research and modelling
- Monitoring of algal bloom development and community structure
- Ecological monitoring to manage water catchments
- Identify and mitigate sources affecting water quality in catchments