Baltic prawn

Taxonomic position: The Baltic prawn, Palaemon adspersus, is a decapod crustacean belonging to the family Palaemonidae. While typically studied in marine biology, in the context of commercial aquaponics and coastal mariculture, it acts as a significant pest that interferes with the sustainable cultivation of aquatic vegetation.

Crops damaged: This species primarily targets marine macrophyte plantations, including species like Zostera marina and various edible seaweed types. In controlled water systems, it can severely graze on seedlings, affecting both the physical structure and the overall health of the biomass intended for harvest.

Biology and life cycle: The lifecycle of Palaemon adspersus is highly adaptable to varying salinity levels and water temperatures. Reproduction occurs through the hatching of planktonic larvae which feed on both microscopic organisms and soft plant tissues. High reproductive rates in sheltered environments allow the population to explode, causing localized damage to submerged crops.

Nature of damage and harmfulness: The crustaceans cause direct mechanical damage by nipping at the leaves and root systems of plants. This grazing activity leaves the plants vulnerable to bacterial infections and rot. In intensive farming, the cumulative loss of leaf surface area leads to reduced photosynthesis, lower crop yield, and significant financial losses.

Protection measures: Management requires a combination of exclusion and environmental modification. Installing fine-mesh barriers is the most effective physical way to keep prawns away from delicate plant roots. Additionally, periodic monitoring and the integration of compatible predatory fish species can help keep the prawn population at a level that does not threaten crop viability.