Chlorella vulgaris - Freshwater Microalgae with Limited Marine Applications

Scientific Classification

Kingdom: Plantae | Division: Chlorophyta | Class: Trebouxiophyceae | Order: Chlorellales | Family: Chlorellaceae | Genus: Chlorella | Species: C. vulgaris

Chlorella vulgaris Overview

Chlorella vulgaris represents a freshwater green microalgae measuring 2-10 micrometers in diameter, featuring simple spherical morphology and bright green coloration. While primarily a freshwater species, exhibits remarkable adaptability to brackish conditions, finding specialized applications in marine aquaculture. Ranks among fastest-growing microalgae cultivated commercially.

Nutritional Analysis

Protein Content: 42-58% dry weight (very high) Lipid Content: 10-20% dry weight Carbohydrates: 12-25% dry weight Chlorophyll: Exceptionally high concentrations Beta-glucans: Immune-stimulating polysaccharides Vitamins: B-complex, vitamin C, vitamin E

Limited Marine Aquaculture Applications

Euryhaline Copepod Culture: Euryhaline copepods including Tigriopus californicus, Apocyclops panamensis, and Tigriopus japonicus tolerate and thrive in brackish water where Chlorella can be cultured. Makes Chlorella practical phytoplankton option for these copepod species.

Artemia (Brine Shrimp) Production: Serves as effective live food for brine shrimp nauplii and adults. High protein content and rapid growth rate make Chlorella economical for large-scale Artemia culture operations.

Aquaponics and Biofloc: In marine aquaponics and biofloc aquaculture, contributes to nutrient removal, oxygen production, and provides supplemental nutrition for filter-feeding organisms in polyculture systems.

Cultivation

Optimal Growth Conditions:

• Salinity Tolerance: 0-15 ppt (freshwater to brackish)
• Temperature: 20-35°C, optimal 25-30°C (68-95°F)
• pH: 6.5-9.0, optimal 7.5-8.5
• Light: 100-300 μmol photons m⁻² s⁻¹
• High Light Tolerance: Can withstand higher intensities than marine species
• Growth Rate: Doubling time 12-20 hours (very fast)

Culture Medium: Grows in freshwater algae media including Bold's Basal Medium (BBM), Bristol's medium, or commercial freshwater fertilizers. For brackish applications, salinity can be gradually increased with marine salt additions.

Reef Aquarium Limitations

Freshwater Species: Cannot survive in full-salinity reef aquarium conditions (35 ppt), making it inappropriate for direct addition to marine reef tanks. Applications remain limited to brackish-tolerant copepod species or indirect enrichment strategies.

Fatty Acid Profile: Lacks EPA and DHA omega-3 fatty acids found in marine phytoplankton, producing instead alpha-linolenic acid (ALA). This limits nutritional value for marine copepods and fish larvae requiring preformed EPA and DHA.

Alternative Applications: Despite marine limitations, remains valuable for culturing brackish copepod species used as live food for marine fish, and for growing supplemental food for Artemia used in reef aquarium feeding programs.