Ko Phiphi Don Island N07°43.802' E98°47.200' Reef Report
Health of the Ton Sai Bay Reef, Ko Phi Phi Don, Thailand

October, 2001

Reef Type:

Fringing reef

Average Water Temperature:



0-5% of reef affected

Average Visibility:

8-10 m

Crown of Thorns Abundance:

fewer than 1 sited per dive

Other observations:

The Ton Sai Bay study site, off Ko Phi Phi Don (Ko is Thai for 'island'), is located within the southern portion of the Had Nopparat Thara-Mu Ko Phi Phi National Park. Established in the mid 1980s, this is Thailand's most accessible and, thus, most popular marine park. The island's fantastic panorama consisting of steep limestone cliffs and white sand lined coves, in addition to its newfound fame as being the site of the recent Hollywood film 'The Beach', has lead to an influx of tourists and a development boom. On the one hand, the designation of the marine park has brought better management and heightened environmental awareness including setups such as the installation of mooring buoys on all of the popular dive sites for the upwards of 20 dive outfits on the island.  But on the other hand, the growing number of visitors has contributed to elevated levels of sedimentation resulting in decreased visibility. Further, though the practices of dynamite fishing and destructive trawling have dwindled, increased traffic over the reef and careless diver practices have taken their toll.

Fish: The area has a wide variety of fish species especially in the butterflyfish and wrasse families. Crescent wrasse are particularly plentiful as are spinecheeks and algae-eating damselfish. The schools of fusiliers have relatively few members probably due to the apparent fishing in the area. Large schools of parrot fish and big individuals are obviously leaving their marks on the coral, as skeletal scars are evident. Generally, the groupers are small in size and the needlefish large. Snorkeling tourists likely feed the Indo-pacific sergeant fish and scribbled rabbit fish, explaining their lack of timidity and interest in humans near the surface.

Coral: The study site chosen within Ton Sai Bay is not one of the more popular dive sites around the island, though it is frequented by snorkelers on a daily basis. The reef extends out from Long Beach (the northern border of the site), beginning at around 3 meters, and wraps around the rock outcrop to the southeast (the southeastern border of the site). The drop off occurs at 11m, approximately 225m from the shallow start of the reef, at which depth the reef gives way to a gradual sandy slope. Strong surge is common within the site, particularly in the more shallow depths around the rock outcrop. Substrate consists of coral on top of sand and rubble, save for the area surrounding the outcrop which is primarily coral on top of rock. Cover ranges from areas of 90% coral to patches of 80% sand and rubble. Porites massive make up a large percentage of the coral cover, however the reef's coral diversity is quite high. In total, we identified various species. The genus most predominant are Porites, Pocillopora, Acropora, Leptoria, Galaxea, Hydnophora, Goniastrea, Symphillia, Lobophillia, Montipora, Goniopora, and Pavona.  In the deeper zone there is less coverage, and diversity is dominated by Porites

Invertebrates: The chosen area displays a great abundance of invertebrate life, the most notable of which are the sea urchins. It is not unusual to count up to 50 of the black spined urchins around one boulder of corals.  Snorkelers and divers have to be careful not to brush up against them.

In the shallower reef area of 3-5m there were also quite a few giant clams in their early development. Other invertebrates sighted included sea cucumbers, nudibranchs and crinoids.

Reef Report
Vitareef Data
Coral& Fish ID
Video Transect
GPS Data