Chlorella vulgaris: Nature's Nutrient Powerhouse Phytoplantkon and Water Purifier

Freshwater ecosystems face mounting challenges from nutrient pollution, which can trigger algal blooms, deplete oxygen levels, and disrupt aquatic food webs. At Hydralife Solutions, we explore nature-based solutions to these problems, and one microscopic organism stands out for its remarkable dual role: Chlorella vulgaris. This single-celled green phytoplankton not only serves as a nutritional foundation for aquatic life but also acts as a highly efficient biological filter for excess nutrients in water bodies.

Microscopic image of a chlorella vulgaris phytoplanton cells.

Chlorella: A Nutritional Goldmine for Zooplankton

Chlorella vulgaris has earned its reputation as one of the most nutritious food sources in aquatic ecosystems. For zooplankton, the tiny animals (aquatic micro-crustraceans) that form a critical link in the food chain between primary producers and fish, chlorella represents an exceptionally high-quality diet.

The nutritional profile of C. vulgaris is impressive. This microalgae contains between 50-60% protein by dry weight, making it one of the most protein-rich organisms on Earth. Beyond protein, chlorella provides essential fatty acids, particularly omega-3 and omega-6 polyunsaturated fatty acids that zooplankton cannot synthesize themselves but require for growth, reproduction, and proper membrane function.

Chlorella also delivers a comprehensive vitamin package including B-complex vitamins, vitamin C, and vitamin E, along with essential minerals such as iron, calcium, magnesium, and zinc. These micronutrients support critical physiological processes in zooplankton, from enzyme function to exoskeleton development. The carotenoid pigments found in chlorella, including lutein and beta-carotene, provide antioxidant protection and contribute to the health and coloration of organisms throughout the food web.

The digestibility of chlorella makes these nutrients readily available to zooplankton. Studies have shown that various zooplankton species, including rotifers, cladocerans like Daphnia, and copepods, thrive when fed diets containing C. vulgaris. The small cell size (typically 2-10 micrometers in diameter) makes it an ideal food source for filter-feeding zooplankton, which can efficiently capture and consume these nutritious cells.

Remarkable Nutrient Uptake Capacity

While chlorella's nutritional value supports healthy aquatic food webs, its capacity to remove excess nutrients from water may be equally important for ecosystem management. C. vulgaris demonstrates exceptional efficiency in consuming nitrogen (ammonia NH3/NH4+, nitrite NO2 and Nitrate NO3) and phosphorus (PO4), the two nutrients most commonly responsible for eutrophication in freshwater systems and harmful algae blooms.

Nitrogen Removal

Chlorella can utilize multiple forms of inorganic nitrogen, making it remarkably versatile in nutrient-polluted waters. Research has documented impressive uptake rates for all three major nitrogen compounds:

Ammonia (NH₃/NH₄⁺) is often the preferred nitrogen source for chlorella because it requires the least metabolic energy to incorporate into cellular proteins and nucleic acids. Under optimal conditions, C. vulgaris can remove ammonia at rates ranging from 10 to 50 mg per gram of algal biomass per day. In practical terms, dense chlorella cultures have been shown to reduce ammonia concentrations in water by 80-95% within 24-48 hours. Hydralife Solutions has seem this through our own work as well when treating irrigation ponds fed by effluent wastewater with ammonia concentrations between .25 and .5 ppm.

Nitrite (NO₂⁻), an intermediate oxidation product of ammonia, is also readily consumed by chlorella. While less research has focused specifically on nitrite uptake, studies indicate that C. vulgaris can efficiently remove this compound at rates of 5-20 mg per gram of biomass per day, helping to prevent nitrite toxicity in aquatic systems.

Nitrate (NO₃⁻), the most oxidized form of inorganic nitrogen, requires additional metabolic effort to reduce and assimilate, but chlorella still demonstrates strong uptake capacity. Removal rates for nitrate typically range from 15-40 mg per gram of biomass per day. The ability to utilize nitrate makes chlorella particularly valuable in agricultural runoff scenarios where nitrate is the predominant nitrogen pollutant.

The actual uptake rates vary based on numerous factors including light intensity, temperature, pH, nutrient concentrations, and the physiological state of the algae culture. Under high light conditions and optimal temperatures (25-35°C), with adequate carbon dioxide availability, chlorella populations can double every 12-24 hours, translating to rapid nutrient drawdown in affected water bodies and an abundance of food to boost copepod populations.

Phosphorus Removal

Phosphorus, often the limiting nutrient in freshwater ecosystems, is another target for chlorella's efficient uptake mechanisms. C. vulgaris absorbs phosphorus primarily as orthophosphate (PO₄³⁻), incorporating it into cellular components including nucleic acids, phospholipids, and ATP.

Research indicates that chlorella can remove phosphorus at rates of 1-10 mg per gram of biomass per day, depending on initial phosphorus concentrations and growth conditions. Studies have documented removal efficiencies of 70-90% of total phosphorus from wastewater and agricultural runoff within several days of exposure to chlorella cultures.

Interestingly, chlorella can also store excess phosphorus as polyphosphate granules when phosphorus is abundant, a process called luxury uptake. This allows the microalgae to continue removing phosphorus from the water even beyond its immediate growth requirements, providing an additional buffer against nutrient pollution.

Practical Applications for Water Management

The combined nutritional value and nutrient removal capacity of C. vulgaris presents enormous opportunities for natural integrated water management strategies. Chlorella-based systems can potentially address multiple objectives simultaneously: improving water quality by removing excess nutrients, producing high-value biomass that can be irrigated as a biostimulant for soils, and by supporting healthy zooplankton populations that sustain fish production in lakes, aquaculture or restoration projects.

At Hydralife Solutions, we're committed to developing scalable, sustainable approaches that harness the natural capabilities of organisms like Chlorella vulgaris. By understanding and optimizing the ecological roles of these microscopic powerhouses, we can work toward healthier, more resilient freshwater ecosystems that benefit both wildlife and human communities and are less reliant on algaecides and chemical treatments.