Studies on Subtropical Scleractinian Coral Communities in Penghu Archipelago
Date Issued
2008
Date
2008
Author(s)
Hsieh, Hernyi Justin
Abstract
To reveal the distributional pattern of scleractinian communities, a video-transect method together with CPCe (Coral Point Count with Excel) analysis were applied to study the coral communities in four sectors: North, East, South, and Inner sea in Penghu Archipelago in 2004-05. The results of cluster analysis showed that coral communities in East and North sectors were grouped together, while those in Inner and South sectors remained as independent groups. Coral communities in North and East sectors were dominated by small colonies and fragments of Acropora spp. indicating that these areas possibly suffering frequent disturbances. Coral communities in Inner sector were dominated by turbidity-tolerant species suggesting that high sedimentation and low light-intensity were possibly the major factors structuring the coral community. Coral communities in South sector were characterized by high species diversity and coral cover, indicating a favorable environment for coral growth and reef development. Results of SIMPER analysis showed that Acropora spp. dominated the South sector, Goniopora sp. and branching Montipora sp. were abundant in Inner sector, while faviids and pectiniids were common in North and East sectors. A. muricata is the most widely distributed species in shallow zone.emperature extremes have traditionally been regarded as the most important factor that affects the distribution and development of reefs. A chill event occurred in winter 2007-2008 and resulted in severe mass mortalities of reef organisms in Penghu Archipelago. The in situ seawater temperature profiles showed that, unusually low SSTs persisted for three weeks and low temperature extremes (LTE) in past three winters were also recorded. The LTEs in South sector (Yupin and Chimei) were about 3-4℃ higher than that of Gupo in North sector. Comparisons of live coral cover (LCC) between 2005 and 2008 showed that significant reduction in LCC and increase of recently dead corals were observed. Branching Acopora spp. and Pocillopora damicornis were the most vulnerable species in the chill event. An index, degree chilling weeks (DCW), was proposed for predicting the impacts of cold sea temperatures. The preliminary data showed that DCW = 1.0 was possibly the threshold of forecasting a chill event. In order to promote the establishment of the first marine protected area (MPA) in Taiwan, the conservation values of 12 reef sites in Penghu Archipelago were evaluated. The results together with a surveillance programme revealed that the Chinwan Inner Bay (CIB) possesses the best coral community in Penghu Archipelago with the highest coral cover, high species diversity and habitat types, as well as a high conservation value. Utilization of biological resources and socio-economic factors of CIB were investigated by intensive field surveys and a complete visit-and-poll survey respectively. Most of the fishing at CIB is for recreational purposes and is characterized by low investment, low harvest rates, high dependence on weather conditions, and self-consumption. The socio-economic data showed that there was basically no direct conflict of interests with local communities at two neighbouring villages, and most local residents indicated that they would support the MPA proposal. A blueprint for a CIB MPA based on the results of these biological and socio-economic investigations is proposed. The involvement of local communities is key to the success of this MPA and environmental education is recommended to promote public awareness.n conclusion, diverse coral communities exist in Penghu Archipelago and the patterns of community structure are closely related to the unique oceanographic and geographic settings. These subtropical coral communities are characterized by catastrophic changes and the intrusion of cold water or the persistence of unusually low temperature is one of the major disturbance factors. The community dynamics following the disturbance such as resilience and resistance as well as the influences of functional groups and the impacts of climate change on these subtropical communities remain to be studied.
Subjects
Subtropical
Scleractinian
coral communities
chill event
degree chilling weeks
marine protected area (MPA)
Type
thesis
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