The productivity and carbon budget of seagrass at Dongsha area
| Autor: | Yen-Hsun Huang, 黃衍勳 |
|---|---|
| Rok vydání: | 2012 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 100 Information of the seagrass productivity and other biotic parameters is very scarce in the world, and even less in the Taiwan area. The function of seagrass bed as carbon sink in tropical sea is also poorly known. Therefore in this study the productivity and other factors of 6 seagrass species in Dongsha were investigated, and also the carbon budget model was constructed to explore the production distribution of the seagrass bed. The results indicated that leaf productivities of Cymodocea serrulata, Cymodocea rotundata, Thalassia hemprichii, Syringodium isoetifolium, Halodule uninervis and Halophila ovalis were between 1.60-5.50, 0.68-4.59, 0.59-3.51, 0.53-1.86, 0.20-1.25 and 0.23-0.79 mg DW shoot-1 d-1, respectively. Although the average productivity of H. ovalis were the lowest, its average relative growth rate reached 79.93 mg DW g-1 d-1, which is 7-19 times higher than the other seagrasses, suggesting being the most rapid-growing seagrass in Dongsha. Overall speaking, there showed a trend of seasonal variations in productivities and relative growth rate of the 6 seagrass species, that is, high in summer and low in winter. The major factors included water temperature, water depth and salinity. In the small lagoon, conditions with high temperature, high light intensity and desiccation could greatly affect the biotic parameters of the seagrasses. The average leaf production in Dongsha seagrass bed was 7.16 g DW m−2 d-1, which is estimated to be approximately 30,362 tons per year, and in which 4,322 tons would be exported to the seagrass ecosystem by forming detritus. During the decomposition process of detritus, the small invertebrates may play a major role for decomposing the above-ground of seagrasses. In terms of carbon budget for the leaf production in the small lagoon and island coastal area respectively, about 83.72% and 76.25% of total carbon were decomposed, 6.76% and 14.43% exported as detritus, 0.73% and 4.69% consumed by herbivory, and 5.74% and 5.93% accumulated as carbon burial. While for the below-ground carbon production, 13.96% and 11.32% were buried into the sediments. For the function of carbon sink, the estimated carbon sequestration of seagrass bed in Dongsha was about 11,367 ton C yr-1, in which 2,892 tons contributed to the biotic community storage and 686 tons were buried in Dongsha area. All of the above indicated the important function of seagrass beds in tropical area as carbon sequestration and carbon burial. The estimated economic value of nutrient cycling, raw materials, carbon right and fish resources of Dongsha seagrass bed was about 95,547 dollars per hectare along with other important ecosystem services making the seagrass bed a unique and irreplaceable natural ecosystem. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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