Marjolijn’s PhD explored the interactions between eutrophication, grazing, and hydrodynamics in tropical seagrass ecosystems in Indonesia (Derawan Archipelago), a global hotspot for green turtles.

 

 

 

• • Eutrophication, Grazing & Resilience: Exclosure experiments revealed that moderate turtle grazing enhances seagrass resilience to nutrient loading by stimulating growth and nutrient uptake.

• • Habitat Collapse in Marine Protected Areas: We documented seagrass degradation in MPAs due to overgrazing by protected turtle populations, highlighting the need for integrated species-habitat management.

• • Coastal Protection Services: Field experiments showed that grazed seagrass meadows stabilize sediments and reduce beach erosion.

• • Toxicity: Lab studies demonstrated how light reduction and nutrient toxicity jointly affect seagrass health, informing management strategies.

• • Sea Turtle Population Studies: We conducted baseline surveys and genetic studies to understand green turtle population dynamics and their impacts on seagrass ecosystems.

• • Impact of Grazing on Seagrass Fauna: We compared seagrass-associated fauna in heavily grazed vs. less impacted areas to assess the broader ecological effects of turtle grazing.

 

 

Restoring Fen Water Bodies: Effects on Aquatic Macroinvertebrates (2006)

Habitat Connectivity of Mangroves, Coral Reefs, and Seagrass Meadows for Reef Fish (Zanzibar, Pemba, Tanzania) (2003)