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THE ENVIRONMENT
Since its introduction into Hong Kong in 1938, the African Giant Snail has become a major pest in vegetable crops and gardens. Farmers are also troubled by several types of slug. One of these, Veronicella is a large, black slug sufficiently different from the other slugs to be placed in a separate family.
Aquatic Life
Marine life forms in Hong Kong are diverse and mainly tropical in character. They include more than 150 commercially important species of fish, crustacea and molluscs. The types and quantities of fish prevalent fluctuate according to seasonal influences and also vary from area to area.
The waters of Hong Kong can be broadly divided into a western sector, influenced by the Zhu Jiang (Pearl) River and predominantly brackish, and the eastern sector, which is more oceanic in character. In some areas, notably the Tolo Harbour, pollution associated with rapid urban development in recent years has led to a decline in the abundance and diversity of marine life. Pollution-sensitive organisms such as coral are now to be found only in a few remote areas. Nevertheless various locations offer natural propagation and nursery grounds for many species of fish, crustacea and molluscs, and provide seasonal feeding grounds for transient predators, such as the Spanish Mackerel, Little Tuna, Dolphinfish, Sailfish and Sharks.
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More than 20 species of shark have been recorded in Hong Kong waters. They are mostly small to medium in size and present little danger to humans. Bigger sharks have been sighted in Mirs Bay in the New Territories and at Stanley and Deep Water Bay on Hong Kong Island. Their presence is a result of the influence of warm ocean current of the South China Sea during the summer months, especially July to September. Sharks which are common in Hong Kong include the Cat Shark, Leopard Shark, Hammerhead Shark, and some species of the True Shark family.
Various species of whales and dolphin have been recorded in Hong Kong waters and strandings occasionally occur. In 1987, three strandings were reported: one Black Finless Porpoise (Neophocaena) in Repulse Bay, one Chinese White Dolphin (Scotalia) and one Spotted Dolphin (Stenella) on Lantau Island.
Plant Life
Situated near the northern limit of the distribution of tropical Asian flora, Hong Kong has an abundant variety of plant life. It is estimated that there are about 2 600 species of vascular plants, both native and introduced.
Before the introduction of conservation measures, the hillsides were becoming increas- ingly bare of trees as a result of cutting, burning and exposure to the elements. On most, the only cover was coarse grass or scrub. Now, many slopes, especially those in the water gathering grounds, have been planted with trees of both local and exotic species. These woodlands, and other areas of countryside, are protected and, with growing numbers of people spending increasing amounts of their leisure time outdoors, are being developed. In addition to making the countryside more beautiful, woodlands are important in the management of water catchments.
Remnants of the original forest cover, either scrub forest or well developed wood- lands, are still to be found in steep ravines. They have survived the destructive influences of man through their location in precipitous topography and the moist winter micro- climate.