In addition to the field results, ecological value of natural watercourse was also justified against existing information. As indicated by HKU freshwater ecology specialists, streams which are oiled for mosquito control by Urban and Regional Services Department (now Food and Environmental Hygiene Department) should be of a lower ecological value than the un-oiled streams (D Dudgeon of HKU, pers comm, May 1999). The locations of streams added with malarial oil were obtained from the Government in June 1999 and those streams which have been marked as oiled watercourses were downgraded to medium ecological value. Based on the information provided by the Regional and Urban Services Department (now Food and Environmental Hygiene Department), ecological value of 1.2 ha of "oiled" natural watercourse were adjusted.

Ecological value of the sandy shore at Sham Wan, South Lamma was upgraded from medium to high as the habitat is a well-documented nesting site for the Green Turtle Chelonia mydas (Morton 1992; McGilvray and Geermans 1997; AFCD 1999). The species is protected under the Wild Animals Protection Ordinance (Cap 170) and the Marine Parks Ordinance (Cap 476). This nesting beach is the only known nesting habitat for Chelonia mydas and was designated as a SSSI on 3 June 1999 because of the presence of nesting turtles. An "*" was given to the beach because of its exceptionally important conservation status.

Sandy beaches which have been developed for recreational use, such as gazetted bathing beaches, are very likely to be disturbed regularly by visitors. These beaches support much lower assemblage diversity and abundance than natural shores or are almost devoid of life (Morton and Morton 1983; Morton et al 1996). Also, as suggested by AFCD (memo dated 3 December 1998), ecological value of gazetted beach should be distinguished from natural sandy shore as the former habitat is very different ecologically from the latter. Therefore, it is considered appropriate to downgrade the ecological value of the 41 gazetted bathing beaches to low. Locations of the 41 gazetted beaches (EPD 1998) are listed in Table 7.3b.