Assessing the spatiotemporal changes, associated carbon stock, and potential emissions of mangroves in Bahrain using GIS and remote sensing data

Abstract

The gray mangrove (Avicennia marina (Forssk) Vierh) constructs one of Bahrain’s most critical ecosystem, severly deteriorating, which has been severely deteriorated by increasing anthropogenic pressures. This study aimed to assess the spatiotemporal changes in the mangrove habitat around Tubli Bay, Kingdom of Bahrain, over the last 50 years through achieving the following: (1) detect the progressive reduction in the mangrove cover using Geographic Information Science and Systems (GISs) techniques and remote sensing data, (2) estimate the changes of above–below ground (AGB-BGB) carbon sequestered in the mangroves using a GIS-based spatial analysis approach, and (3) estimate the potential carbon emission changes from the loss of original mangrove habitats. Various GIS and remotely sensed data were employed in the study, including high-resolution satellite images from Worldview-3, Worldview-2, IKONOS, and QuickBird, coupled with true-color orthorectified aerial photographs. Additional data was acquired from fieldwork and the ancillary GIS maps. Image processing of the satellite data was conducted using ENVI 5.5 Software. ArcGIS 10.8 was used for digitizing the mangrove areas in all satellite imagery. The final maps were used to calculate mangrove area changes and carbon loss due to land reclamation activities. Our results indicated that Bahrain lost more than 95% of the natural mangrove cover from 1967 to 2020. The mangrove extent area’s net loss reached 280 ha during 1967–2020, as it declined from 328 ha in 1967 to 48 ha in 2020. The primary cause of the decline was land reclamation associated with urban development. The rates and causes of the loss varied both spatially and temporally. Due to land clearing, the total carbon stored in the mangrove habitats declined from 34,932.2 Mg C ha−1 in 1967 to 5112 Mg C ha−1 in 2020. Consequently, the potential carbon Sequestration decreased from 128,200.44 Mg CO2e ha−1 in 1967 to 18,761.04 Mg CO2e ha−1 in 2020. Our study urges for more efficient conservation of the remaining mangroves in Bahrain to sustain their valuable ecosystem services particularly carbon sequestration.