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Perspectives on Marine Environment Change in Hong -Kong and Southern China, 1977-2001 (ed . B. Morton). Proceedings o f a n Internationa l Worksho p Reunio n Conference, Hon g Kon g 21-26 October 2001. Hong Kong: Hong Kong University Press , 2003. HONG KONG'S PENAEID PRAWNS: A DECADE LON G RECORD O F CHANGE IN COMMUNITY COMPOSITIO N S.F. Leung The Swire Institute of Marine Science, The University o f Hong Kong , Hong Kong and K.F. Leun g Environmental Protection Department , The Government of the Hong Kong Special Administrative Region , 28/F, Southorn Centre, 13 0 Hennessy Road, Wan Chai, Hong Kon g ABSTRACT This paper present s th e results o f a series of benthic traw l survey s t o examine spatia l and tempora l change s i n th e specie s compositio n an d distributio n o f penaei d praw n resources i n th e northeastern , eastern , southeaster n an d northwester n water s o f Hon g Kong, representing a full spectru m of marine conditions, from oceanic to estuarine. The waters of Hong Kong also experience frequent anthropogeni c disturbances, in particular, trawling, sewage discharges, sediment dredging an d dumping. Nineteen specie s of penaeid prawns were recorded in Hong Kong during the 1989, 1992, 1993 , 1995, 1998 and 2001 surveys. The species composition an d abundance of penaeid prawn s were , however , quit e distinc t amon g th e differen t region s o f Hon g Kong's waters . Fifteen specie s o f penaeid prawn s wer e collected fro m th e northeastern water s of Hong Kong which include Tolo Harbour, Tolo Channel and Mirs Bay during the 1989, 1995 an d 200 1 surveys . A positive gradien t o f increasin g specie s diversit y extendin g from polluted Tolo Harbour to less polluted Mirs Bay was observed in all surveys. The species diversity o f the prawn community i n Tolo Harbour had, however, increased in the intervenin g year s betwee n 198 9 an d 200 1 wherea s th e opposit e wa s recorde d fo r Tolo Channe l an d Mir s Ba y durin g th e sam e period , probabl y attributabl e t o improvements i n wate r qualit y i n Tol o Harbou r an d wate r qualit y deterioratio n an d 616 S.F. LEUNG & K.F. LEUNG intensive fishing pressur e in the latter. The catastrophic hypoxia event which occurre d in northeaster n water s i n 199 4 wa s als o considere d responsibl e fo r th e reduce d abundance, biomass and diversity o f penaeid prawns in 1995 . The 1993 , 1995 and 2001 surveys in northwestern waters collected thirteen specie s of penaeid prawns. The prawn assemblages change d considerably ove r the intervening years amon g the three surveys, probably attributabl e to continuous seabe d disturbanc e for extensive reclamation, sediment dumping and dredging and shrimp trawling activities. Sixteen specie s o f penaei d prawn s wer e obtaine d fro m th e 1992 , 199 5 an d 199 8 surveys in the southeastern waters of Hong Kong. Despite the effects o f sand dredging, the dominant specie s remained th e same among the three surveys. Penaeid abundanc e showed a marked increase in the 199 5 and 199 8 surveys as compared with that of the 1992 survey. The results of the re-survey of West Po Toi and Beaufort Island sub-area s in 200 1 indicated a n increase i n biomass an d averag e individua l weigh t o f prawns a s compared with the corresponding 199 8 values. This provides further evidenc e to support the hypothesis that reworking of the seabed due to sand dredging creates habitat refugi a where trawling is not practicable and thus allows the penaeid prawns to re-populate the seabed and subsequentl y gro w to a greater size. In contras t t o othe r surveye d areas , th e easter n oceani c water s o f Hon g Kon g represent a region far from urban activities and are subject to seabed disturbance mainly by trawling. Only nine species of penaeid prawns were recorded from the 1995 and 2001 surveys, indicatin g a les s divers e praw n fauna . Bot h specie s...

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