There are thousands of distinct algae varieties that are purposefully cultivated around the world. However, many types of algae are still only grown on a minor scale with backyard and neighborhood cultivation ponds. Only a handful of algae varieties are currently in widescale production on a commercial level. Unless you’re experienced in algaculture, you should probably stick to algae with an established market and existing demand. Otherwise, prepare to develop demand for your own new product if you decide to cultivate a rare and unusual type of algae.
Microalgae and Phytoplankton
As the tiniest plants in most environments, microalgae and phytoplankton produce a surprising amount of oxygen. They are responsible for keeping both saltwater and fresh waterways from getting overwhelmed with nutrients. Unfortunately, inappropriate algae growth resulting from nitrogen runoff can also damage waterways. This happens because dissolved oxygen levels can rapidly decline in a way that hurts other plants and fish. Since microalgae are single cell organisms, they tend to stay tiny and form a loose cloud or long filament growth underwater.
Macroalgae
Many people think of tiny bits of green algae and long strands of firm seaweed as being different plants, but they share the same family and are closely related. Macroalgaes grow large and develop many cells per plant, producing a form that is closer to what we’re used to from dealing with land-based plants. Unlike microalgaes that can vary in their food sources, all macroalgaes are self-feeding. However, they still absorb nutrients like nitrogen from the water. Unlike land-based plants and many other aquatic plants, every part of seaweed contains chlorophyll and contributes to photosynthesis, not just the leaves.
Spirulina
Spirulina is commonly referred to blue-green algae. However, it’s actually a form of bacteria that is believed to have developed the photosynthesis process that plants use. Despite being a bacteria, spirulina uses the sun’s rays and nutrients in the water to create food with chlorophyll. This is why it’s commonly called a form of algae despite being in a separate family and having a different internal structure. It’s one of the most widely grown products in modern aquaculture due to high demand for the finished powdered as a dietary supplement and feed additive for animals. It does require much of the same care as algae, but careful testing is needed to verify the safe types of cyanobacteria aren’t mixed with toxin-producing ones that can be spread by the wind.
Chlorella
One of the most efficient producers of biomass, protein, and nutrients is chlorella. The same refers to an entire genus of tiny green algae that only need carbon dioxide, a low level of minerals, and sunlight to thrive and rapidly reproduce. Its photosynthesis efficiency rating can reach as high as 8% in optimal conditions, making it more efficient to produce calories than any land-based plant. Unlike other plant-based protein sources, it is 20% fat by volume, making it a more well-rounded food source than other algae. It is also widely sold as a nutritional supplement for humans and animals alike, but the claims for these products are less widely supported than its value as food.
Seaweeds
Macroalgaes, like seaweed, were among the first water plants to receive intensive cultivation. Asian and Polynesian cultures have been relying on various ocean-based plants as food and medicine sources for thousands of years. When wild populations weren’t sufficient to keep up with demand, the world’s first algaculture systems were devised. Early attempts at seaweed farming took the form of simple nets and baskets placed in open water where bits of plants were seeded to regrow. Today’s seaweed farms are much more complex, involving thousands of acres of open ponds, water quality tracking equipment, and industrial scale harvesting equipment. But, no matter the scale or complexity, seaweed remains a relatively easy and profitable water plant to grow for food, cosmetics, and medication.
Irish Moss
You may have never heard of Irish moss or sea moss, but you’ve likely seen the word carrageenan on a food package at some point. Chondrus crispus, also known as Irish moss, is a lichen-like seaweed that grows in the ocean around rocky coastlines in North America and Europe. The dark purple material is coral-like in its branching appearance. The thick and viscous gel, known as carrageenan, that is extracted from this moss is best known. Carrageenan is a natural, safe, food stabilizer or thickening agent that helps add body to soups, sauces, yogurts, and similar products. It’s also an important additive for finishing beer and wine. Only 8% of Irish moss is still harvested wild from the sea around Ireland, with South East Asian farmers producing the majority of the supply with seaside ponds.
Both macro- and microalgaes will grow happily in open pond systems, but they require very different water volume and conditions to reach their full potential. Macroalgaes, like seaweed, tend to take more space than microalgae. They also produce a higher volume of finished product after drying. Microalgaes are compact and can generate a lot of value in a small space, but only if there’s a high demand for the particular variety you grow.
