Algae Crash Course: Information About Algae Around Bocas Del Toro

If you’ve ever wondered what all that smelly black stuff is on the beach, read on and we may be able to answer a few of your questions. The Playa Istmito Project is a participatory science project in which Bocatoreño students partner with the Smithsonian Tropical Research Institute to learn about algal blooms, how they occur, and how they affect our local coastline, in addition to helping researchers collect data on a persistent local algal bloom that washes up on Playa Istmito. For more information on the project, check out our previous article in the Bocas Breeze.

As we move forward with our project, we would like to give the public an overview of what algae is, algae families found in Bocas, and more information about the species we are interested in. Knowledge is power!

Are algae the same as other plants?

Algae share similarities with other plants but are different in many ways. Algae and other plants are autotrophs: that means they produce their own food. Both have chlorophyll in their cells and use photosynthesis to convert solar energy into carbs.

Algae, however, lack the vein-like vascular system that plants have evolved over time to transport nutrients and water throughout the plant. Plants have roots, stems, and leaves to make the process of photosynthesis easier. Algae don’t have these structures. ¹

Algae are confusing to define as they come in many different sizes and forms. To give some context, it is thought that there are between 30,000 to over 1 million species of algae ², so… yeah. Let’s start with microalgae, which include diatoms and dinoflagellates. These are microscopic, single cell organisms that are essential to life on Earth. They are the base of the marine food web and produce a large portion of Earth’s oxygen. ¹˒³ AND they look cool.

Next up, we have macroalgae, or seaweed. Macroalgae are larger species of algae that range in size from small tufts of floating green things that act as food for marine life, to giant kelp forests that can act as habitat for a complete ecosystem. ¹ They’re classified based on the type of light-absorbing pigment they have: red algae, green algae and brown algae. Red and brown algae are mostly found in marine environments, while green algae are mostly found in freshwater. Also, the classification of algae doesn’t necessarily mean that the seaweed will be that color. ⁴

Finally, we have cyanobacteria, or blue-green algae. Blue-green algae are actually bacteria, not plants, but because they are photosynthetic, are also primary producers, and live in water, they are often grouped with microalgae. They’ve been around for a long time (over 3 billion years) and were the first organisms to release oxygen into Earth’s atmosphere, which before cyanobacteria was an oxygenless space land. This oxygen production allowed for the evolution of metabolic processes (for example, plants changing carbon dioxide into glucose, or the synthesis of proteins from amino acids to form DNA) by other organisms, and thus cyanobacteria are what allowed for all other life to flourish on Earth. ⁵ Nice, thanks cyanobacteria! They are diverse and live predominantly in marine environments but can also be found in extreme locations such as deserts and glaciers. Many also produce toxins, which in in large quantities can be a risk to animal and human health. ⁶ Not so cool, cyanobacteria.

What is an algal bloom?

An algal bloom is when algae that live in equilibrium in a natural environment grow in excess and much faster than they would normally. Algal blooms happen when trace nutrients that a particular species of algae needs to grow, like nitrogen or phosphorus, enter an aquatic environment at concentrations higher than the natural level. These nutrients can leak into a system from different sources like untreated sewage, agricultural or stormwater runoff, or enriched rainfall. If weather conditions are also favorable (temperature, sunlight, wind direction), algae can grow prolifically and become a nuisance or even a hazard to marine life and humans. When large blooms form, they prevent sunlight from penetrating the water column, which can hinder the growth of microalgae and marine plants that need sunlight to survive, killing the primary producers and negatively impacting the marine food web. To add insult to injury, once algal blooms use up all the available trace nutrients, they die and are eaten by bacteria; these bacteria use up a lot of the dissolved oxygen in the marine environment to eat the decaying algae, further stressing marine animals who need the available dissolved oxygen to survive. If the algal bloom in question is toxic, their toxins can lead to fish kills and can pose a risk to swimmers. ⁷ However, algae is not bad! It’s a vital part of any marine ecosystem. But, like anything in life, there can be too much of a good thing.

What are some genera of algae that we can find in Bocas? 

Here we’ll list some common macroalgae species you’re likely to find on a beach walk.

Halynmenia spp.

Species of algae from the Halynmenia genus are red algae distributed in temperate and tropical waters. ⁸ Some species from the genus that have been documented in Bocas include Halynmenia duchassaingii and Halymenia psuedofloresia.

Halynmenia duchassaingii and Halymenia psuedofloresia

Caulerpa spp.

Caulerpa spp. is a genus of green algae. They are one of the largest single cell organisms, and strangely have multiple nuclei per cell. ⁹ Documented species within Bocas include Caulerpa sertularioides, Caulerpa nummularia, Caulerpa prolifera and Caulerpa racemosa.

Caulerpa sertularioides, Caulerpa nummularia, Caulerpa prolifera and Caulerpa racemosa

Padina spp.

Algae species within the Padina genus, identifiable by their peacock tail shape, are brown algae found in tropical intertidal environments that are known as some of the only brown algae species that are calcareous, meaning their plant bodies are hardened with calcium carbonate. ¹⁰ Some species of Padina in Bocas include Padina perindusiata, Padina pavonica, and Padina hatiensis.


Bryopsis spp.

Bryopsis species are within a genus of green algae. They are known to contain some bioactive derivatives that may aid in treatment of various diseases ¹¹ and their ecological success is attributable to endosymbiotic relationships with bacteria that live in their cells. ¹² Bryopsis species are sometimes considered pests, proliferating in aquariums and creating “green tide” algal blooms. ¹³ Species found in Bocas include Bryopsis ramulosa.

Crash Course on Algae 13

Dictyota spp.

A genus of brown algae found in tropical and subtropical areas with potential medicinal properties. ¹⁴ Bocas species include Dictyota crispata and Dictyota pulchella.

Other recognizable species include 1. Spatoglossum schroederi, 2. Derbesia turbinata and 3. Thalassia testudinum. 4. Haloplegma spp.

1. 2. 

3.  4. 


What is all the black stuff on the beach?

We suspect that the algal bloom that washes up on Playa Istmito are cyanobacteria known as Lyngbya majuscula. They are able to grow on substrate up to 30 meters below the surface and can be dislodged and pushed to shore by wave action. ¹⁵ L. majuscula grow at maximal rates between 24 – 30°C, which suggests that algal blooms may increase in severity with projected rising temperatures. ¹⁶ The cyanobacteria produce toxins of which concentration is directly correlated with peak bloom abundance, which can be harmful to swimmers and animals if touched or consumed. ¹⁶

Crash Course on Algae 20

Why does the algal deposit sometimes wash up on the beach in balls?

When the algae balls are examined under a microscope, we can see that they consist of L. majuscula and shards of silica spicules, the spicules likely originating from sea sponges around Bocas. The mixture of filamentous blue-green algae combined with the sponge spicules in a turbulent environment with lots of wave action may lead to balls forming as they saltate across the bottom, later to be deposited on the beach.

Crash Course on Algae 21

Why is this algal bloom happening?

We’re not entirely sure. We think it may be correlated to increased nutrient input into the Bocas marine environment, but we can’t say for certain. It may also be particular weather and current patterns. We’ll be sure to update the public on any conclusions we make! Our citizen science project, Proyecto Playa Istmito, in which students from Bocas del Toro help Smithsonian scientists investigate an algal bloom happening in Las Cabañas, Isla Colón, will continue in March when school is back in session.

That’s all! Thanks for reading through. If you have further questions or an algae sample you’d like to identify, reach out to us via email ( and we’ll help you from there.

Special acknowledgement to the Smithsonian Women’s Committee for their sponsorship of Proyecto Playa Istmito and to Alberto Saa for foundational work with this project.


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The Bocas Breeze is a digital and print newspaper proudly serving the Bocas del Toro community since 2004; reporting news, advertising local businesses and promoting tourism in Bocas del Toro, Panama.

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