Coastal biodiversity in Mauritius, Rodrigues and other outer islands is being squeezed by erosion, poor siting of development, polluted runoff, over-exploitation, invasive species risk, and climate shifts. Protecting what remains—and recovering what’s been lost—depends on planning discipline (setbacks, wetland protection), clean water, habitat restoration, resilient fisheries, strong biosecurity, and climate-smart infrastructure that works with, not against, the coast.
The coastal biodiversity of the Republic of Mauritius is under simultaneous pressure from shoreline erosion, unsustainable coastal development, pollution, natural hazards, invasive alien species (IAS), climate change, and over-fishing. These stressors interact, degrading beaches, reefs, seagrass, and mangroves, and ultimately affecting livelihoods—especially for communities concentrated in low-lying coastal zones.
1) Coastal erosion
Scale of the issue. An estimated 45–50% of beaches show active erosion (Integrated Coastal Zone Management - ICZM). Roughly 7 km of beach are already seriously affected (Martin, T., et al. “CBD Fifth National Report – Mauritius, CBD, 2015).
Why it matters. Erosion narrows beaches, undermines infrastructure, reduces natural storm protection, and diminishes tourism value—exacerbating poverty where incomes depend on coastal resources.
Key drivers. Sea-level rise, more energetic waves during storms/cyclones, sediment starvation (e.g., hard structures interrupting sand transport), and land-based activities that increase nearshore turbidity.
2) Coastal development & wetland loss
Unsustainable patterns. Backfilling and construction on wetlands have destroyed ~90% of wetland area, often without adequate drainage or sewer networks.
Consequences. Loss of wetlands eliminates natural water storage, filtration, and flood buffering; beach-hardening structures (seawalls, groynes) can worsen down-drift erosion and degrade habitat complexity.
3) Pollution & eutrophication
Sources. Domestic and agricultural runoff, failing/absent wastewater systems, improper disposal of used oil and batteries, and terrigenous sediment from catchment erosion.
Impacts. Seagrass meadows and nearshore reefs suffer eutrophication, algal blooms, and reduced light penetration; sediment smothers coral and seagrass, lowering fish nursery function. Overfishing of herbivores further tips the balance toward algal dominance.
4) Over-fishing and habitat stress
Lagoon pressure. Chronic fishing pressure—especially on reef herbivores and invertebrates—reduces ecological resilience to warming and pollution. Gear that damages reef substrate compounds the problem.
5) Invasive alien species (IAS)
Data gaps. The Global Invasive Species Database lists no confirmed marine IAS for the Mauritius EEZ, but marine IAS status is poorly known.
Risk pathways. Ballast water, hull biofouling, aquaculture stock movements, and marine debris can introduce or spread IAS. Absence of records ? absence of risk; early detection and rapid response capacity is essential.
6) Climate change & natural hazards
Observed signals in Mauritius (Statistics Mauritius)
* Average temperature increase of 0.74–1.2 °C (vs. 1961–1990 baseline).
* Annual rainfall down by ~8% since the 1950s.
* Sea-level rise around 5.6 mm/yr.
* Beach loss of ~18,500 m² over the last two decades.
* Coral bleaching episodes in 1998, 2009, 2016.
* More intense extremes: stronger cyclones and heavy-rain events, with flash floods (e.g., 2008, 2013).
Implications. Hotter, higher, and stormier seas stress corals; sea-level rise and storm surges amplify erosion and flooding; declining rainfall tightens freshwater constraints that affect estuaries, mangroves, and water quality.
