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LAMARR B. TROTT
monthly temperature of the air, and the sea surface temperatures of Tolo Harbour shows striking correlation. The temperature of the water falls well below 20°C (14.5°C) during the winter months. This would normally mean that reef-building corals would not be found here, and indeed a reef as such does not exist. However, we do have flourishing patch reefs, often comprised by species of reef-building corals, making this condition in Hong Kong unique biologically. Our geographic position being on the Tropic of Cancer would normally indicate a subtropical climate; however, winter-time cold air and water currents greatly influence the temperature of our environment, whether we consider the land or the sea. Our marine fauna is thus derived from the Indo-Pacific faunal realm, but it is also influenced by more temperate forms. A characteristic of the sea is the fact that the offspring of most marine creatures live for a time in what is termed the plankton, and drift freely in the sea at the mercy of ocean currents. If they can tolerate the conditions of the environment to which these currents bring them, then they become established in that area.
Of other conditions of the marine environment than temperature that are important to Hong Kong, we can mention two in passing. One is salinity. Fresh water from the Pearl River flowing into our waters during and after the rainy season greatly reduces the saltiness of the waters of Deep Bay. The organisms living there must thus be able to tolerate a great change in salinity or be able to migrate to more favorable areas when the salinity becomes too low. Correlated with this is the sediment that is washed down with the Pearl River outflow. Many organisms cannot tolerate great amounts of sediment settling on top of them. Corals are one of the best examples. Thus, our corals are concentrated in areas of the Colony less under the influence of the Pearl River — Mirs Bay, for example.
My own research at the Chinese University has been concentrated in the area of Tolo Harbour. The site of the Chinese University on the shore of the harbour at Ma Liu Shui makes work in this area ideal. We have begun a general survey of the Harbour, which has included preliminary investigations of the mudflat areas, the level bottom communities, the fishes, and studies on associations between organisms. One of the primary aims of our program is to train students in the marine sciences.