Phuket, Marine and Coastal Systems

Phuket’s marine and coastal environments represent the central operational interface of its tourism economy. Western beaches generate the vast majority of destination revenue, while shallow coastal waters host dive operations, excursion fleets, and recreational activities. However, cumulative human pressures—ranging from coastal construction and untreated runoff to anchor damage and marine heatwaves—have pushed these fragile marine systems into critical stress states.

6.1 Status and Degradation Trends of Coral Reefs

Monitoring data from the Department of Marine and Coastal Resources (DMCR) indicates a long-term decline in the health of fringing reefs surrounding Phuket and its satellite islands.

  • Reef Condition Breakdown: Surveys conducted across key reef zones (including Patong Bay, Kata Bay, Nai Harn, and Ko Racha Yai) classify approximately 72% of surveyed reefs as “damaged” or “severely damaged”, with less than 10% rated in “good” condition.
  • Thermal Bleaching: Ocean warming events have caused severe, repeated bleaching. Major thermal stress events in 2010, 2016, and recent regional heatwaves have caused mass mortality in sensitive branching corals (Acropora spp.), shifting community structures toward more resilient but slower-growing massive corals (Porites spp.).
  • Sedimentation and Water Quality: Coastal earthworks, construction site runoff, and untreated municipal wastewater discharge elevate turbidity and nutrient levels in shallow waters. Sediment deposition smothers coral polyps, blocks sunlight required for photosynthesis, and triggers macroalgal blooms that outcompete juvenile corals.
  • Recreational and Maritime Impacts: Intensive dive/snorkel tourism, anchor dragging from private boats and tour vessels, and direct physical contact by inexperienced swimmers continue to inflict localized mechanical damage on shallow reef flats.

6.2 Mangrove Systems and Coastal Protection

While historical tin mining and early aquaculture development cleared large areas of mangroves along Phuket’s eastern coast, remaining mangrove forests (approximately 2,200–2,500 hectares) are now under formal protection.

  • Coastal Stabilization: Mangrove root structures trap terrestrial fine sediment, prevent coastal mudflat erosion, and act as natural shock absorbers against monsoon storm surges and tidal waves.
  • Blue Carbon Reservoir: Mangrove ecosystems store up to four times more carbon per hectare than terrestrial tropical forests. Protecting Phuket’s eastern mangrove belt preserves critical carbon sinks while maintaining regional water quality in Phang Nga Bay.
  • Encroachment Pressures: Despite protected status, mangrove edges remain vulnerable to piecemeal encroachment for marina infrastructure, residential docks, and commercial developments along coastal estuaries.

6.3 Beach Morphodynamics, Erosion, and Coastal Infrastructure

Phuket’s western beaches are dynamic sand systems regulated by seasonal monsoon waves. During the Southwest Monsoon, high-energy waves move sand offshore; during the calmer Northeast Monsoon, gentler swells rebuild the beach profile.

Human interventions have severely disrupted this natural sediment balance:

  1. Hard Infrastructure Backshoring: Resort sea walls, promenade concrete structures, and roads built directly on primary dune systems block natural beach movement. Wave energy reflects off hard seawalls, accelerating scour and sweeping sand into deeper water where gentler swells cannot return it.
  2. Severe Erosion Hotspots: Critical beach erosion is documented along Karon, Kamala, Rawai, and sections of Bang Tao beach. At several nodes, seasonal beach narrowing threatens coastal public roads and resort property boundaries.
  3. Hard Engineering vs. Soft Adaptation: The widespread placement of concrete seawalls, geotextile bags, and rock revetments has frequently exacerbated erosion downstream along adjacent beach stretches, demonstrating the need for soft beach nourishment and dune restoration models.

6.4 Marine Protected Areas (MPAs) and Spatial Management

Protected marine environments around Phuket fall under two primary administrative designations:

  • Sirinat National Park: Established in 1981, covering 90 km² (68 km² marine area) along the northwest coast. It protects coral reefs, sea turtle nesting grounds, and coastal pine forests. However, high visitor volumes around Nai Yang and coastal commercial activity test the park’s enforcement capacities.
  • Protected Environmental Areas (ONEP Mandate): The entire province is designated as an Environmental Protection Area under national environmental law, establishing specific restrictions on building heights, slope development, and coastal setback zones.
Governance Challenges in MPAs

Enforcement in marine zones is complicated by overlapping jurisdiction between the Department of National Parks, Wildlife and Plant Conservation (DNP), the Department of Marine and Coastal Resources (DMCR), and the Royal Thai Navy. Limited vessel patrols, inadequate mooring buoy infrastructure, and illegal fishing or anchoring in protected zones remain persistent management gaps.

CASE STUDY 1: Marine Spatial Management and Habitat Restoration in Sirinat National Park

Location: Sirinat National Park, Thalang District, Northern Phuket

Primary Issues: Coral degradation, sea turtle habitat disruption, recreational overcrowding, and marine litter.

Overview & Context:

Covering 13 km of northern coastline (including Hat Mai Khao, Hat Nai Yang, and Hat Nai Thon), Sirinat National Park represents Phuket’s most critical marine conservation node. It hosts some of the last remaining sea turtle nesting sites on the island and protects fringing reefs subjected to heavy commercial excursion traffic.

Key Interventions Implemented:

  • Zoning and Mooring Buoy Networks: To eliminate anchor damage on sensitive reefs, the DMCR and DNP installed designated mooring buoy zones off Hat Nai Yang, banning vessel anchoring within active coral reef boundaries.
  • Seasonal Nesting Protections: During sea turtle nesting season (November–March), beach patrols increase, motorized water sports are restricted, and artificial lighting along beach resort perimeters is regulated to reduce hatchling disorientation.
  • Community Coral Restoration: Partnership programmes involving local dive operators and research units from the Phuket Marine Biological Center (PMBC) have deployed artificial substrate structures and nursery-grown coral fragments (Acropora) to rehabilitate degraded reef patches.

Evidence-Based Outcomes & Limitations:

While mooring buoy installation significantly reduced direct physical anchor destruction in protected zones, coral recovery remains constrained by regional ocean warming and land-based nutrient runoff. The case illustrates that marine spatial zoning is effective against localized physical impacts, but cannot succeed without parallel land-based wastewater controls and broader climate adaptation.