Rumput laut eucheuma cottoni semakin meningkat dan berkembang disepanjang pantai amal kota tarakan. kegiatan yang selama ini dilakukan oleh masyarakat setempat tidak berdasarkan kajian ilmiah tentang kesuaian dan daya dukung lingkungannya. berdasarkan hal tersebut, maka perlu dilakukan penelitian mengenai kualitas air pada lokasi budidaya rumput laut eucheuma cottonii di perairan pantai amal kota tarakan. penelitian ini bertujuan untuk mengetahui kondisi lingkungan terutama kualitas perairan di lokasi budidaya rumput laut. penelitian ini dilaksanakan pada bulan september 2011- juni 2012 di perairan pantai amal, kecamatan tarakan timur, kota tarakan, provinsi kalimantan timur. metode penelitian menggunakan metode deksriptif. hasil pengukuran kualitas air di perairan pantai amal kota tarakan meliputi: suhu (28,70-31,13oc), salinitas (20,86-26,06 ppm), kecerahan (1,02-1,31 meter) derajat keasaman (7,45-8,05), oksigen terlarut (5,60-6,72 mg/l), fosfat (0,002-0,092 mg/l) dan nitrat (0,012-0,423 mg/l). hasil pengukuran menunjukan bahwa daya dukung kualitas air di perairan pantai amal kota tarakan baik untuk dilakukan budidaya rumput laut e. cottonii. untuk keberlangsungan budiaya rumput laut di pantai amal kota tarakan, diperlukan upaya pelestarian lingkungan perairan secara terpadu dan berkelanjutan. kata kunci: kualitas air, area budidaya rumput laut, pantai amal kota tarakan

Eucheuma cottoni growing and evolving along the amal beach, tarakan city. the activities that have been carried out with local society have not by scientific studies and carrying capacity. based on this research, it is necessary to research about the quality of water at the location cottonii eucheuma in the waters of amal beach tarakan city. this research aims to determine the condition of the environment, especially the quality of water at the site of location cottonii eucheuma. the research was carried out in september 2011 - june 2012 in the waters of amal beach, eastern of tarakan, tarakan city, province of east kalimantan. the method of research was used descriptive method. the measurement results of water quality in the waters of amal beach tarakan city include: temperature (28.70 to 31.13 ° c), salinity (20.86 to 26.06 ppm), brightness (1.02 to 1.31 meters) the degree of acidity (7 0.45 to 8, 05), dissolved oxygen (5.60 to 6.72 mg / l), phosphate (0.002 to 0.092 mg / l) and nitrate (0.012 to 0.423 mg / l). measurement results show that the carrying capacity of the water quality in the waters of amal beach, tarakan city charitable better to do. cottonii. for continuity on the amal beach, tarakan city, required water efforts conservation in an integrated and sustainable manner. keywords: water quality, seaweed farming area, amal beach tarakan city