RELATIONSHIP BETWEEN COMMUNITY STRUCTURE AND CARBON STOCKS IN THE SEAGRASS ECOSYSTEM OF KARIMUNJAWA AND KEMUJAN ISLANDS, JEPARA, CENTRAL JAVA

• Main Author: Setya Nur Kumala, Amelia
• Format: Theses
• Language: Indonesia
• Subjects: Ilmu hayati ; Biologi
• Online Access: https://digilib.itb.ac.id/gdl/view/48036
• Institution: Institut Teknologi Bandung

It is estimated that Indonesia stores 17% of the world's "blue carbon", and therefore has an important role in mitigating global climate change. This estimation, however, is assumed to be below the actual value because there are still many unexplored seagrass ecosystems. On the other hand, the relationship between carbon stocks and community structure in Indonesia's highly diverse seagrass ecosystems has not been much studied. This issue needs to be addressed because while seagrass ecosystems are considered as the most effective coastal ecosystem in storing carbon, they are also experiencing continuous degradation. This potential, and the urgency for coastal ecosystem conservation and optimal management, justifies the need for research studies on the potential of blue carbon storage in Indonesia’s seagrass ecosystems. This study aims to (1) describe and compare the seagrass community structure in six locations on the coast of Karimunjawa and Kemujan Island, Jepara, Central Java; (2) measure seagrass carbon stocks at those six locations and estimate the island’s total carbon stocks; and (3) determine the relationship between community structure and seagrass carbon stocks. The six sampling locations are Nyamplung Ragas (Bobi Beach), Alang-Alang, Anora, Koin (Pokemon Beach), Telaga, and Legon Bajak. Analysis on the relationship between seagrass community structure and carbon stock was based on the comparison and correlation between vegetation analysis data and carbon stock estimation at the six sampling locations. Vegetation analysis was conducted in 33 square plots measuring 0.5 m2 in a 10,000 m2 sampling area at each location. Community structure is described through the calculation of seagrass density, frequency and cover, then compared through several indices, i.e., importance value, diversity, evenness, dominance, and similarity. Carbon stock was calculated from three carbon pools, i.e., aboveground living biomass (ABG), belowground living biomass (BLG), and sediment, with organic carbon content (OCC) analysis using the Kurmies method. Biomass carbon stock was obtained using the correlation between seagrass density per species, seagrass dry weight per species individual, and seagrass OCC per species, while sediment carbon stock was obtained by multiplying dry bulk density (DBD), sediment dry weight per sampling volume, and sediment OCC. Seagrass species found on the coast of Karimunjawa-Kemujan Island were Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Halodule pinifolia, Halophila ovalis, Halophila minor, Syringodium isoetifolium, and Cymodocea serrulata. The highest seagrass density, frequency, cover, and importance value index at six locations varied among three species, i.e., E. acoroides, T. hemprichii, and C. rotundata. The highest diversity index was found in Nyamplung Ragas (1.55), the highest evenness index was found in Legon Bajak (0.81), and highest dominance index was found in Telaga (0.52). The highest estimated carbon stock of 426.17 Mg C ha-1 was found in Telaga with E. acoroides as the dominant species, while the lowest of 127.42 Mg C ha-1 was found in Koin with T. hemprichii as the dominant species. The estimated total carbon stock on the coast of Karimunjawa and Kemujan islands covering an area of 404,276 hectares is 97.299,23 Mg C. E. acoroides contributed the most to the overall seagrass biomass carbon stocks on the coast of Karimunjawa and Kemujan Island with a value of 157.56 Mg C (76.8%) and its dominance in the community showed a high positive correlation with the total seagrass carbon stocks (r = 0,92; p = < 0,05).