Title Balance between harvesting pressure and protection: Implications for barren ground formation in Hong Kong
Authers P.O. Ang, Jr., K.Y. So, T.W. Li, F.F. Yeung., S.Y. Wong. and C.K. Woo
Citation Bull. Fish. Res. Agen. No.32, 1-10, 2010
Abstract
In recent years, there is an increasing awareness of the importance of coastal communities as ecological habitats. Marine protected areas (MPA) are being established and harvesting of marine organisms within these protected areas is being regulated. MPAs provide an opportunity for dynamic regulating mechanisms within coastal community to be examined. A case in point is the Tung Ping Chau Marine Park (TPCMP) in Hong Kong established in 2001. From October 2002 to March 2004, temporal variations in algal and herbivore dynamics were observed in general monthly surveys. The density of herbivores in Lung Lok Shui (LLS), one of the sites known to support extensive bed of Sargassum, was low (0.76 individual/100cm2 ) and herbivores did not appear to be an important factor in structuring the algal community.
 In 2006 to 2007, the population of the short-spined black urchin Anthocidaris crassispina increased significantly, from < 1 individuals/m2 in pre-MPA period to up to 40 individuals/m2 , likely a result of restricted harvesting of these urchins since the establishment of TPC as a marine park. One serious and unexpected consequence of this was the decimation of Sargassum population in LLS due to extensive urchin grazing. The cover of Sargassum was completely reduced, forming barren ground. Sea urchin grazing became the most important structuring force in this coastal community and was previously put under check due to harvesting by human. A question can therefore be put forward as to how important is human harvesting pressure on sea urchins, or other herbivores like fish, contributing to the dynamics of the coastal algal community. This factor may be more important than previously thought.
URI http://www.fra.affrc.go.jp/bulletin/bull/bull32/1-10.pdf