SUMMARY
Air limbah budidaya diketahui mengandung berbagai senyawa organik dan anorganik yang dapat memberikan pengaruh langsung terhadap penurunan kualitas perairan di sekitarnya. Penelitian ini bertujuan untuk mengetahui sebaran nilai amonia secara temporal sebagai dampak aktivitas budidaya di wilayah Bali Utara. Kegiatan pengambilan sampel air dilakukan per bulan dari Februari hingga November 2018 di empat lokasi perairan, yakni dua lokasi buangan air hatcheri (Desa Gerokgak, Desa Penyabangan), satu perairan lokasi budidaya pembesaran (Teluk Kaping di Desa Sumberkima), dan satu lokasi kontrol (Desa Pemuteran). Dari setiap lokasi dipilih daerah budidaya terpadat di darat dan ditentukan tiga titik sampling di perairan dengan jarak 50 m, 100 m, dan 300 m dari bibir pantai. Hasil penelitian menunjukkan bahwa amonia pada ketiga lokasi budidaya terlihat pada besaran yang relatif sama (0,1-1,9 mg/L), sedangkan kontrol terlihat mempunyai nilai yang cenderung sedikit lebih rendah (< 0,01-1,8 mg/L). Amonia berada pada kisaran yang cukup tinggi (> 0,5 mg/L) pada bulan Februari hingga April 2018 di keempat lokasi sampling. Tren nilai amonia yang relatif tidak berbeda di antara titik sampling (50 m, 100 m, dan 300 m) mengindikasikan bahwa kualitas air di perairan Bali Utara cukup merata, dengan input N dan cenderung tinggi dan cukup konsisten hingga jarak 300 m dari bibir pantai.Aquaculture wastewater contains organic and inorganic materials which, in many cases, contribute directly in the degradation of water quality of the neighboring area. This study aimed to determine the temporal distribution of chemical and physical parameters of water quality in Northern Bali coastal waters adjacent to mariculture sites with emphasize in ammonia distribution. Water samplings were carried out from February to November 2018 in three locations near three mariculture sites (Gerokgak, Penyabangan, Kaping Bay) and one control location (Pemuteran). The densest mariculture activity in the three sites was selected as the sampling area in which three sampling locations were determined at a distance of 50 m, 100 m, and 300 m perpendicularly from the sites. The results showed that ammonia levels in waters adjacent to the three mariculture sites have relatively similar variation between 0.1 and 1.9 ppm. However, the control area has lower ammonia levels (between 0.01 and 1.8 ppm). The level of ammonia concentration increased considerably from February to April in all sampling stations reaching more than 5 ppm which is above the maximum threshold for mariculture activity. The other parameters (DO, pH, salinity, and TSS) were found to be consistent and within the standard required for mariculture activity. This study recommends that reduced stocking density, stocking time outside of the months when ammonia content is high, and improvement of mariculture waste treatment could effectively improve water quality and subsequently increase fish production in the area.