Pendugaan Cadangan Karbon dan Indeks Kualitas Ekosistem Lamun di Pulau Giligenting, Kabupaten Sumenep-Madura

Abstract

Penyerapan CO2 di atmosfer dapat melalui tumbuhan darat dan lautan dengan mekanisme fotosintesis, kemudian diubah menjadi biomassa dalam bentuk jaringan tubuh. Karbon organik lamun disimpan dalam bentuk biomassa atas dan bawah substrat yang sangat tergantung pada kondisi lingkungan seperti morfologi lamun, kerapatan, tutupan, dan tipe substrat. Penelitian ini bertujuan mengukur nilai pendugaan cadangan karbon biomassa lamun serta menganalisis indeks kualitas ekosistem lamun di perairan Pulau Giligenting, Sumenep. Penelitian dilakukan selama Bulan Maret hingga Juli 2023 di tiga stasiun penelitian dengan metode transek garis. Data stok karbon diperoleh menggunakan metode konversi karbon yang dikaitkan dengan nilai kerapatan, persentase tutupan lamun, makroalga, dan epifit, serta karakteristik lingkungan perairan. Empat jenis lamun ditemukan di lokasi penelitian yaitu Enhalus Acoroides, Thalassia hemprichii, Halophila ovalis, dan Cymodocea rotundata. Kerapatan tertinggi jenis H. ovalis (44,40±75,65 ind/m2). Tutupan makroalga tertinggi di ST-1 (4,48±4,81%) dan epifit tertinggi di ST-1 (20,45±15,21%). Lamun jenis E. acoroides ditemukan di semua stasiun dengan total biomassa 175,20±45,90 gbk/m2, hal ini disebabkan kesesuaian tipe substrat berpasir di Pulau Giligenting. Pendugaan stok karbon di Pulau Giligenting adalah 3,82±0,8546 tonC, dengan rentang 0,5683±0,1715 sampai 0,7884±0,5156 tonC/ha, dan status kualitas ekosistem lamun tergolong kategori sedang.

The atmospheric CO2 absorption can be through land and coastal vegetation by photosynthesis mechanisms, which are then converted into biomass in body tissues. Seagrass organic carbon is stored as aboveground and belowground biomass that highly depends on environmental conditions, such as seagrass morphology, density, coverage, and substrate types. The study aims to measure the estimated value of carbon biomass reserves and analyze the seagrass ecosystems quality index in the Giligenting waters, Sumenep District-Madura. The study was conducted from March to July 2023 at three sites using the line transect method. Carbon storage was obtained using the conversion carbon method associated with seagrass density, the percentage of seagrass, macroalgae, and epiphytes cover, and the characteristics of the waters. Four seagrass species were at the study site, namely Enhalus Acoroides, Thalassia hemprichii, Halophila ovalis, and Cymodocea rotundata. The highest density value by H. ovalis (44,40±75,65 ind/m2). The highest macroalgae cover at ST-1 (4,48±4,81%) and epiphyte cover at ST-1 (20,45±15,21%). E. acoroides was found in all stations, with the total biomass value reaching 175,20±45,90 gdw/m2, due to the suitability of the sandy substrate type on Giligenting Island. The carbon storage estimation of seagrass beds on Giligenting was 3,82±0,8546 MgC, with an average number of 0,5683±0,1715 to 0,7884±0,5156 MgC/ha, and the status of the seagrass ecosystem quality is classified as a moderate category.