KUALITAS LINGKUNGAN PERAIRAN DAN POTENSI PRODUKSI IKAN KAWASAN KONSERVASI TERUBUK BENGKALIS (Tenualosa macrura Bleeker, 1852)
Authors: Amri Khairul , Winarso Gathot , Muchlizar Muchlizar 
Published: March 2018

Terubuk Bengkalis (Tenualosa macrura) yang hidup di perairan Bengkalis dinyatakan terancam punah akibat eksploitasi berlebih dan penurunan kualitas perairan. Penelitian ini bertujuan untuk menganalisa kualitas perairan habitat terubuk Bengkalis, menggunakan data parameter oseanografi hasil pengukuran in-situ. Selain itu, data penginderaan jauh berupa citra Landsat 8 digunakan untuk analisa tutupan mangrove (hutan bakau) serta citra MODIS-Aqua (Moderate-resolution Imaging Spectroradiometer) untuk analisis produktivitas primer (NPP). Penelitian dilaksanakan selama April-November 2015. Hasil penelitian menunjukkan total luas tutupan mangrove yang teridentifikasi citra Satelit Landsat 8 (2015) mencapai 11.736,2 Ha, berkurang sekitar 4.470,8 Ha dalam waktu 12 tahun (2003-2015) dengan laju kehilangan 372,5 Ha/tahun. Dari aspek oseanografi, kawasan konservasi ikan terubuk merupakan perairan dangkal dengan tingkat kecerahan rendah (0,54-0,95 m); suhu perairan relatif tinggi berkisar 29,15-31,87 0C (rata-rata 300C) dan salinitas rata-rata tergolong rendah (28,77-29,22 ppt). Nilai sebaran pH dan oksigen terlarut/DO juga rendah yakni pH 6,3-8,9 (rata-rata pH 7) dan DO 3,90-4,98 mg/l (di bawah Baku Mutu Air Laut). Komposisi substrat dasar didominasi lumpur, dengan prosentase 67,4-89,8%, sehingga perairan ini umumnya keruh. Perairan ini tergolong subur (eutropik) dengan kelimpahan fitoplankton tinggi (23.584 - 95.616 sel/l) terdiri dari 32-52 genera. Produktivitas primer juga tinggi, rata-rata 288,87 mgC/m2/hari dengan potensi produksi ikan 3.680,2 ton/tahun. Terubuk Bengkalis (Tenualosa macrura) is an endemic tropical shad fish that live in Bengkalis waters.This species has been declared endangered due to over exploitation and environmental degradation. The current research aimed to analyze the environmental quality of the species. The data used in this research were consited of in-situ measurement and remote sensing data: Landsat 8 Satellite imagery for mangrove cover observation and MODIS (Moderate-resolution Imaging Spectroradiometer) imagery for Net Primary Productivity (NPP). The results showed that the cover of mangrove vegetation along the coast of Bengkalis Island dentified by Landsat 8 Satellite imagery was11.736,24 Ha. The total loss of cover mangrove vegetation is estimated about 4.470,83 Ha, decreased drastically in 12 years (2003-2015) with a loss rate of 372.5 Ha/year. The habitat of shad fish is shallow water category. The water quality was too turbid (brightness level 0.54-0.95 m); warm water temperature of 29.,15-31.87 0C (average 300C); and low salinity (28,77-29,22 ppt). The relatively low pH and dissolved oxygen content were determined: pH ranged between 6,3-8,9 (mean7) and the DO: 3,90-4,98 mg/l (under the Sea Water Quality Standard).The substrat was dominated by mud (67,4-89,8%) in Bengkalis Strait sub area due to the turbidity. However, these waters are euthropic level category with a high abundance of phytoplankton ranging from 23,584-95,616 cells/l and the species richness varies from 32-52 species. The primary productivity level of waters was also quite high was average of 288,87 mgC/m2/day resulting an estimation of potential of fish biomass value about 3.680,2 ton/year.