Plants

Biology of Aquatic Plants

Photosynthesis and Respiration

Photosynthesis (using light):

CO2 + H2O + light → glucose + O2

Plants absorb CO2 and release O2 → in planted aquariums, O2 levels rise during the day

Breathing (always, especially at night):

glucose + O2 → CO2 + H2O + energy

At night, plants also consume O2 → in dense plantings, O2 levels can drop in the early morning

Essential Nutrients

Macronutrients:

• Nitrogen (N): source → nitrates/ammonia in water
• Phosphorus (P): phosphates
• Potassium (K): from fertilizer or tap water

Micronutrients (trace elements):

• Iron (Fe): essential; a deficiency causes chlorosis
• Magnesium (Mg): a component of chlorophyll
• Manganese (Mn), Zinc (Zn), Boron (B), Copper (Cu — caution: toxic to shrimp)
• Calcium (Ca): Cell Structure

Types of Nutrition by Location

• Water column: plants with fine leaves (Cabomba, Hornwort) — absorb nutrients directly from the water
• Substrate: plants with strong root systems (Echinodorus, Cryptocoryne) — they absorb nutrients mainly from the bottom
• Mixed: the majority

Growth Areas

• Submerged: always underwater (Vallisneria, Anubias)
• Emergent plants: partly in water, partly in air (Hygrophila, some Echinodorus)
• Floating plants: on the surface (Pistia, Limnobium, Salvinia)

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