Water quality biomonitoring using macroinvertebrates in Way Besai, Sumberjaya, West Lampung

Forest conversion to agriculture such as coffee garden and rice field occurred in way besia watershed, Sumberjaya,lampung province, Indonesia particularly during information era,1998.Land clearing, soil tillage , fertilizing and pesticides application as part of the activities during forest conversion to agriculture. Those activities effected to the water quality along the stream and river through sedimentation, nutrient accumulation and pesticide recidue.water quality is detemined by accessing three classes of attributes;physical,chemical and biological. Both of chemical and physical attributes need high cost on laboratory analysis than biological assessment using microvertebrates. Evaluating biological community or a stream through assessment microverterbrates provide a sencitive and cost effective means on determining stream condition.The objectives of this research are ; (1)to kkow the taxonomic diversity of aquatic microinverterbrates along the stream.(2)to assess water quality condition based on functional feeding group and(3) to assess water quality condition based on family biotic index.30 plots along way Besai river with three nested streams (Way petal,Way Ringkih and Air Hitam) choosed as samples.Aquatic microinverterbrates collected from the waterbody in 10 m stream length and moved diagonally across the stream for 5 minutes during April 2005 (dry season) using 'kick technique) microverterbrrates were identified up to family level.High family reachness and abundance occured in the stream around the forest, followed by stream around coffee gareden. Physical and chemical contents in the stream such as subsrate of the stream vegetation around the stream and river bank, chemical organic content effect to the family richness and adundances . Chironomidae is the most common in Way Besai and found in 83% of sampling plot. Cordulegastridae, Hyydreaenidae were only food in forest areas.more shreders found in the stream with a high organic matter content, more scrapers were found in the stream with an open area.more collectors were found in the stream dominated by sand and loam substrate and more predators were found in the stream diminated by stones substrate.predators group decreased gradually from upsream to down stream.Based on the family biotic index (FBI)water quality in Way Besai, Sumberjaya were gategorized from excellent to very poor. stream around forest area and some coffee garden in Air Hitam indicated excellent quality, which means organic pollution were unlikely. The stream which had high shredders also showed a high FBI value, and organic pollution occured in the area.

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