Prymnesiales algae

Prymnesiales are a group of haptophyte algae that play a significant role in the biological management of aquatic environments used in agriculture. While they are not pathogens of terrestrial crops, they function as severe environmental stressors in aquaculture and hydroponic systems, where water quality is a primary production factor.

The causative agent involves various species within the order, most notably Prymnesium parvum. These organisms produce complex exotoxins known as prymnesins. When a bloom occurs, these toxins are released into the water, acting as a biological hazard that inhibits the normal physiological functions of nearby aquatic organisms and sensitive plant species.

Agricultural sectors most affected include rice cultivation and large-scale hydroponic farming. The toxins can cause root system inhibition and necrosis in water-dependent crops, while in aquaculture, they are responsible for mass mortality events, leading to substantial economic losses for farmers relying on natural water bodies.

Symptoms of an infestation are often observed through rapid changes in water quality parameters. Typical signs include the sudden appearance of foam on the water surface, a shift in water color to a brownish hue, and a decline in crop vigor characterized by stunted growth and yellowing of the foliage due to root-level toxin absorption.

Development conditions favor these organisms when environmental parameters are suboptimal. Factors include high salinity, stable temperatures between 15°C and 25°C, and high concentrations of orthophosphates or nitrogenous runoff, which trigger rapid reproduction cycles and subsequent toxin release.

Protection and preventive measures focus on monitoring water chemistry and ecosystem balance. Effective strategies involve:

• Regular testing of water for nutrient spikes.
• Installation of UV sterilization units for closed-loop systems.
• Implementation of buffer zones to prevent agricultural runoff.
• Application of selective algaecides under strict agronomic supervision.