Serasah mangrove yang jatuh akan mengalami proses dekomposisi dan menghasilkan unsur hara yang dimanfaatkan tanaman mangrove itu sendiri serta sumber makanan bagi biota di perairan. Tujuan penelitian ini adalah untuk mengetahui laju dekomposisi serasah daun mangrove api-api (Avicennia alba) di Kawasan Konservasi Mangrove dan Kepiting Pamusian Kota Tarakan. Penelitian ini dilakukan pada bulan Juli sampai Agustus 2021 di Kawasan Konservasi Mangrove dan Kepiting Pamusian Kota Tarakan. Penentuan stasiun penelitian menggunakan metode purposive sampling berdasarkan jenis mangrove yang dominan yaitu Avicennia alba pada 2 titik stasiun. Hasil penelitian menunjukkan laju dekomposisi serasah daun mangrove Avicennia alba pada stasiun 1 sebesar 0,55 g/hari dan pada stasiun 2 sebesar 0,53 g/hari dan pada stasiun 3 0,52 g/hari. Proses dekomposisi paling tinggi terjadi pada stasiun 1 karena berhadapan langsung dengan laut dan memiliki perendaman yang lebih singkat dan perendaman pada saat pasang tertinggi.
Kata Kunci: Avicennia alba, Laju Dekomposisi, Mangrove

Mangrove litterfall undergoes a decomposition process and produces nutrients that are utilized by the mangrove plants themselves and food sources for biota in the surrounding waters. The objective of this research was to determine the rate of decomposition of api-api mangrove (Avicennia alba) litterfall in the mangrove and Crab Conservation Area, Pamusian Subdistrict, Tarakan City. This research was conducted from July toAgustus 2021 in the Mangrove and Crab Conservation Area, Pamusian Subdistrict, Tarakan City. The research stations were determined using a purposive sampling technique based on the dominant type of mangrove, namely Avicennia alba at 3 station points. The result showed that the rate of decomposition of Avicennia alba mangrove litterfall at station 1 was 0.55 g/day, at station 2 was 0.53 g/day, and at station 3 was 0.52 g/day. The highest decompotion process occurred at station 1 because it was directly adjoining the sea and had a shorter immersion and its immersion occurred at the highest tide. Keywords: Avicennia alba, Decompotision Rate, mangrove