Caribbean reef systems typically include mangroves, fringing reefs with the seagrass meadows in the reef lagoons sandwiched in-between these two ecosystems. Multiple biological, biogeochemical and physical interactions exist among the mangroves, seagrass meadows and reefs. These interactions enhance their functioning, or possibly even allows for the existence of the other ecosystems. Here, the role of the seagrass meadows in sediment and coastal dynamics in reef systems will be addressed, by combining information from literature and own results from studies in the Mexican Caribbean.
Results/Conclusions
Seagrasses create a more benign hydrodynamic environment by wave-baffling, and sediments are trapped in an extensive below-ground root rhizome mats. Accompanying calcareous algae produce annually tons of calcareous sand per hectare. Seagrasses and calcareous algae in undisturbed reef lagoons tend to be resilient to extreme events such as storms and hurricanes. However, increasing human-induced disturbance, such as eutrophication and coastal development are changing the community specific composition throughout the Caribbean towards faster-growing and species that are less resilient to physical disturbance. Synergistic effects of these human-induced environmental deterioration and natural disturbances may result in unexpected collapse of the seagrass meadows. Such collapse may result in beach erosion, which was shown for a Mexican Caribbean reef lagoon. In a reef system, the coral reefs are most vulnerable the effects of global climate change; when the reefs degrade or disappear, the diverse seagrass habitats in the reef lagoons will most likely follow their fate. For management solutions for maintenance of tropical coasts and beaches, it is important to raise awareness of the interdependence of the ecosystems of the reef system, and of the role of seagrasses and associated calcareous algae in maintaining coastal stability through sediment stabilization and calcareous sand production.