Tetraselmis chui - Large Cell Premium Marine Phytoplankton

Scientific Classification

Kingdom: Plantae | Division: Chlorophyta | Class: Chlorodendrophyceae | Order: Chlorodendrales | Family: Chlorodendraceae | Genus: Tetraselmis | Species: T. chui (T. chuii)

Comprehensive Tetraselmis chui Species Profile

Tetraselmis chui (also spelled Tetraselmis chuii) represents a premium large-cell marine microalgae measuring 10-14 micrometers in diameter, significantly larger than Nannochloropsis (2-4 micrometers). This green marine phytoplankton features four flagella for motility and distinctive chloroplast structures. The larger cell size makes Tetraselmis ideal for feeding larger copepod species, brine shrimp, mysid shrimp, marine fish larvae, and large-polyp corals.

Each cell possesses four equal-length flagella arranged in a square pattern at the anterior end, providing swimming motility. Cells appear somewhat flattened with oval to quadrangular outlines. A single cup-shaped chloroplast occupies most cell volume, giving cultures characteristic bright green coloration. Multiple pyrenoids (carbon fixation structures) appear as dense regions, and a single eyespot enables light detection for phototaxis.

Nutritional Analysis

Protein Content: 40-52% dry weight - Among the highest protein levels in any microalgae species. Contains all essential amino acids including exceptional lysine (7.2-8.9% of protein), leucine (8.5-10.2%), arginine (6.8-8.3%), and glutamic acid (11-14%). This balanced profile ensures complete protein nutrition without amino acid limitations.

Lipid Content: 8-14% dry weight - Moderate lipid level reflecting emphasis on protein over lipid storage. Contains alpha-linolenic acid (ALA, 15-25% of fatty acids), EPA (2-8%), linoleic acid (8-15%), and palmitic acid (25-35%). While EPA content is lower than specialists like Nannochloropsis, the balanced nutrition combined with exceptional protein creates ideal profile for many applications.

Vitamins: Rich in B-complex vitamins, exceptional vitamin C content (1000-2500 μg/g dry weight or 0.1-0.25%), vitamin E (150-400 μg/g), vitamin K, providing complete vitamin nutrition.

Pigments: Chlorophyll a and b (characteristic of green algae), lutein (0.2-0.4% dry weight), zeaxanthin, beta-carotene, supporting vision development and providing antioxidant benefits.

Minerals: Comprehensive profile including calcium, phosphorus, magnesium, potassium, iron (500-2000 mg/kg), zinc, manganese, copper, and notably high iodine (50-300 mg/kg) supporting thyroid function.

Marine Aquaculture Applications

Large Copepod Species Nutrition: The 10-14 micrometer size matches feeding apparatus of larger copepods:

• Pseudodiaptomus pelagicus: Tropical calanoid (1.0-1.5mm adults) achieving 20-35% faster growth and 25-40% higher fecundity on Tetraselmis versus Nannochloropsis alone. Females produce egg sacs with 15-30 eggs every 2-3 days.

• Acartia tonsa: Cosmopolitan temperate calanoid (0.8-1.2mm) used in marine fish hatcheries worldwide. Well-fed females produce 10-30 free-spawning eggs daily. Tetraselmis supports excellent egg production.

• Centropages species: Larger calanoids (1.2-2.0mm) consuming Tetraselmis readily, suitable for larger fish larvae filling size gap between small copepods and Artemia.

• Adult Tisbe biminiensis: Larger adults (particularly gravid females) efficiently consume Tetraselmis, supporting substantial energetic demands of producing 3-5 egg sacs with 20-40 eggs each.

Research shows populations fed Tetraselmis alone achieve 85-95% of optimal mixed-diet performance, while Nannochloropsis-only diets achieve only 60-70%, demonstrating Tetraselmis value as near-complete diet.

Brine Shrimp (Artemia) Enrichment: Tetraselmis provides superior Artemia enrichment versus traditional baker's yeast:

1. Complete Nutrition: 40-52% protein plus essential fatty acids, vitamins, minerals, carotenoids
2. Optimal Cell Size: 10-14 micrometers matches Artemia filtration capabilities for efficient feeding
3. High Digestibility: Green algae cell walls maximize nutrient transfer from phytoplankton to brine shrimp to fish
4. Enhanced Coloration: Carotenoids transfer to Artemia creating attractive orange-red color
5. Improved Survival: Complete nutrition supports better Artemia survival during and after enrichment

Studies on sea bass larvae showed 300-400% survival improvements and 150-200% growth increases with Tetraselmis-enriched versus un-enriched Artemia. Commercial hatcheries producing grouper, snapper, sea bream, cobia employ Tetraselmis for Artemia enrichment during rotifer-to-Artemia transition phase.

Large Polyp Coral Feeding: LPS corals particularly benefit from Tetraselmis due to larger cell size matching larger polyps:

• Euphyllia species (torch, hammer, frogspawn): Polyps 1-3cm diameter respond with increased tentacle extension and feeding. Regular feeding (2-3x weekly, 50,000-200,000 cells/ml for 2-4 hours) supports faster growth, improved tissue fullness, enhanced fluorescence, better recovery from stress.

• Trachyphyllia/Wellsophyllia (open brain corals): Massive polyps exceeding 10-15cm display visible feeding responses within minutes. Regular feeding increases growth rates 30-50% by tissue area and 40-60% by skeletal weight versus photosynthesis alone.

• Cynarina lacrymalis (button corals): Extremely large polyps (10-20cm) inflate substantially during feeding. Regular feeding (3-5x weekly) dramatically improves survival of this challenging species, with well-fed specimens doubling in size over 12-24 months.

• Scolymia, Acanthastrea, Micromussa, Lobophyllia, Catalaphyllia, Symphyllia: All demonstrate improved coloration, tissue expansion, and growth with regular Tetraselmis feeding programs.

Small Polyp Coral Benefits: Despite smaller polyps, many SPS species benefit from Tetraselmis supplementation:

• Acropora species: While smaller Nannochloropsis may be more efficiently captured, nutrient-dense Tetraselmis cells provide more nutrition per captured cell. Mixed diets (Nannochloropsis + Tetraselmis) may be optimal.

• Montipora, Pocillopora, Stylophora, Seriatopora: All demonstrate feeding responses and benefit from supplementation, with research showing 10-30% of nutrition from heterotrophic feeding supplementing zooxanthellae photosynthesis.

Soft Coral Applications: Leather corals (Sarcophyton, Sinularia), pulsing Xenia, and other soft corals actively filter-feed with research demonstrating 20-40% of nutrition from heterotrophic feeding despite abundant zooxanthellae.

Culture Parameters

Optimal Growth Conditions:

• Salinity: 25-35 ppt optimal (tolerates 15-40 ppt)
• Temperature: 18-28°C, optimal 22-25°C (64-82°F)
• pH: 7.8-8.6, optimal 8.2-8.4
• Light: 150-300 μmol photons m⁻² s⁻¹
• Photoperiod: 16:8 or 24:0 light:dark
• Aeration: Continuous with CO2 supplementation
• Growth Rate: Doubling time 18-30 hours

Culture Medium: Standard marine media including F/2, Walne's, Conway, or commercial aquaculture fertilizers. Requires nitrogen (nitrate, urea), phosphorus (phosphate), trace metals (iron, manganese, zinc), and vitamins. Tolerates slightly lower nitrogen than many species, suitable for continuous culture systems.

Advantages in Reef Systems

Superior Protein Content: 40-52% protein density makes Tetraselmis among most nutritionally complete phytoplankton for marine aquaculture.

Excellent Feed Conversion: Large cell size and high nutritional density result in superior feed conversion ratios, reducing overall phytoplankton volume required for copepod production.

Extended Shelf Life: Dense cultures maintain viability longer when refrigerated compared to smaller species, providing convenience for hobbyists and small-scale operations.