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Langkat merupakan salah satu kabupaten yang memiliki kawasan mangrove terluas di Provinsi Sumatera Utara. Sejalan dengan pertumbuhan dan perkembangan penduduk maka kebutuhan akan lahan semakin meningkat pula. Hal tersebut juga sangat berpengaruh terhadap peningkatan aktivitas konversi lahan mangrove. Berangkat dari permasalahan tersebut perlu adanya monitoring perubahan kawasan mangrove dalam 30 tahun terakhir. Metode yang digunakan dalam penelitian ini adalah pendekatan penginderaan jauh dan sistem informasi geografis untuk mengekstrak dan menganalisis informasi perubahan luasan mangrove yang terjadi selama ini 30 tahun terakhir (1989-2019). Hasil penelitian menunjukkan perubahan luasan mangrove sangat efektif dilakukan dengan menggunakan Citra Landsat 5 TM dan 7 ETM Pemisahan mangrove dengan objek non mangrove menggunakan metode klasifikasi unsupervised. Analisis kerapatan mangrove menggunakan formula NDVI dengan bantuan software Envi4.7. Hasil citra Landsat 5 TM dan citra Landsat 7 ETM+ diperoleh tingkat kerapatan mangrove sedang mendominasi distribusi hutan di pesisir pantai Kabupaten Langkat. Adapun pada rentang waktu 1989 hingga 2019 terjadi penurunan di kawasan mangrove di Langkat seluas 7.606,3234 Ha. Faktor penyebab berkurangnya kawasan mangrove di Langkat adalah konversi lahan menjadi pertanian dan perkebunan.

Collaboration in the management of mangrove areas is a role for every social element in local government, the community, and the private sector. Co-management is an alternative solution in the form of management that integrates the roles and interests of everyone in the mangrove rehabilitation program. This study aims to analyze the role and level of influence of the interests of each actor in mangrove rehabilitation activities in Langkat Regency. The research method uses descriptive-qualitative data collected from the results of questionnaires, interviews; Field observations are processed in the form described in the description in the tabulation. From the results of this study, the form of joint management in mangrove rehabilitation is at a consultative stage where the government starts to consider local views in the decision-making process, the level of participation of each stakeholder is in a low category, so this Study recommends that the form of participation of each stakeholder can be improved through the form of joint regulations, sustainability programs and systematic work distribution that is disseminated to every implementer of mangrove rehabilitation programs in Langkat District.

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Most of the cities of Bengkulu are coastal areas (71.87%) under substantial pressure due to infrastructure development. This condition has affected the mangrove ecosystem and ecological degradation and has induced abrasion. In this study, we aimed to analyze the existing conditions of the mangrove ecosystems in the city of Bengkulu, particularly the composition and distribution of the mangrove species and the determination of the water quality. We collected vegetation data using exploratory methods and direct observation at 13 research sites. We measured the water quality in situ in terms of the temperature, salinity, pH, and dissolved oxygen (DO) at the sites, performed a vegetation analysis, and analyzed the turbidity, total dissolved solids (TDSs), biochemical oxygen demand (BOD), chemical oxygen demand (COD), nitrate, nitrite content, ammonia, and phosphate concentrations ex situ in the laboratory. We found 52 vegetation species in the research sites, which included 11 true mangrove species, 9 associated mangrove species, and 31 coastal and land flora. A total of 24 species are categorized under the least-concern (LC) category of the IUCN (International Union for Conservation of Nature) Red List, and one species is in the data-deficient (DD) category. We categorized the water quality of the mangrove ecosystems in the city of Bengkulu as relatively good, with all the parameters below the national water quality threshold, except for the nitrite concentration in the Bengkulu River estuary. Proper management needs to be developed for the conservation and restoration of mangrove ecosystems to sustain their functions.