Biological monitoring of the rocky intertidal community along the pollution and exposure gradient in Victoria Harbour, Hong Kong SAR, China
Rocky intertidal communities support a high biodiversity. However, they are also easily affected by disturbances, especially human induced disturbances like marine pollution. The recovery process would be very long even after abatement actions have been taken. Also, the outcome of this recovery process cannot be readily predictable. Marine environments in Hong Kong are seriously exposed to pollution problems. The rocky intertidal areas along Victoria Harbour have been suffering from marine pollution impacts for a long time. Recently, the Hong Kong Government has implemented the Harbour Area Treatment Scheme (HATS) aimed at improving the water quality of Victoria Harbour. While water quality of this Harbour was reported to have improved after the scheme, whether the natural rocky shores along the Harbour have recovered from the pollution impact remain unclear. Responses of rocky intertidal community assemblages, as well as those of some particular intertidal species, i.e. the barnacle Tetraclitra japonica, in the light of HATS, were the main focuses of the present study. ; From June 2004 to May 2007, the community assemblages of six selected rocky shores along the Victoria Harbour were monitored. From west to east, these six natural shores were Peng Chau, Green Island, Causeway Bay, Hoi Xum Park, Heng Fa Chuen and Tung Lung Chau. Results showed that Hoi Xum Park was completely different from the other five sites with the lowest diversity index . In contrast, the diversity indices of the other sites ranged from 2.13 0.37 to 2.25 0.21. During the study period, only 11 species were recorded in Hoi Sum Park. This was far lower than that in the other shores (number of species ranged from 32 to 38). In addition, the community structure of Hoi Xum Park was only 25% similar to that of the other sites. This high dissimilarity was caused by high coverage of the barnacle Balanus amphitrite and cyanobacteria Chroococcus sp., and the absence of the limpet Petalloida saccharina in Hoi Xum Park. Except for Hoi Xum Park, a ...