Dugong

Systematic position: The dugong (Dugong dugon) belongs to the order Sirenia and the family Dugongidae. It is the only living species within the genus Dugong. While primarily recognized as a unique marine mammal, its feeding behavior classifies it as a major consumer of seagrass, which significantly affects the biomass density of marine flora in its habitat.

Crops damaged: The dugong feeds exclusively on seagrasses, favoring species from the Potamogetonaceae and Hydrocharitaceae families, such as Halophila, Halodule, and Cymodocea. Extensive feeding can denude vast areas of the seafloor, effectively removing the primary production layer in coastal zones where seagrass meadows are essential.

Biology and life cycle: Dugongs are large herbivorous mammals adapted to life in warm coastal waters. They possess specialized mouthparts for uprooting seagrass. Their reproduction rate is very low, with females giving birth to a single calf every three to seven years. They migrate across shallow coastal waters, following the availability of their preferred nutritional sources.

Nature of damage and harm: The harm caused by dugongs is characterized by the physical removal of seagrass rhizomes, not just the blades. This prevents the regrowth of the meadows. The resulting loss of habitat density harms local biodiversity, particularly affecting the nurseries of various commercial fish and crustacean species, impacting local marine ecosystem stability.

Protection measures: The dugong is a protected species under international law, making traditional pest control measures inapplicable. Instead, management strategies focus on:

• Establishing Marine Protected Areas (MPAs).
• Restricting watercraft traffic to prevent injuries.
• Improving water quality to support faster seagrass regeneration.
• Community-based monitoring of coastal seagrass meadows.