INDEK BIOTIK FAMILI SEBAGAI INDIKATOR KUALITAS AIR SUNGAI GAJAHWONG YOGYAKARTA
Abstract: The purpose of this
research was to determine water quality level of Gajahwong River, Yogyakarta
with the present of macroinvertebrate as biologycal indicators. The sampling
was conducted in the Gajahwong River fl ow from Pakem subdistrict in Sleman
regency to Pleret subdistrict in Bantul regency. There were six sampling
stations, and sampling was conducted once a week for two months from mid
October to December 2011. Samples of macroinvertebrate were collected by poking
substrate in front of surber net mouth so that macroinverterbrate were drifted
into surber and trapped in pocket net. Samples were preserved in 5%
formaldehide solution then identifi catifi ed and anlyzed in the laboratory.The
species number of macroinvertebrate were analyzed as biotic index, such as
diversity index, evenness index, dominance index and biotic family index (BFI).
Environment parameter measured include physical and chemical properties. The
physical parameter collectednamely subtrate type, river depth and stream width,
fl ow velocity, temperature and total suspended solid (TSS). The chemical
parameter collected namely dissolved oxygen, free CO2, alcalinity,organic
matter and pH. The results showed that fl ow rate was varied 0.51-0.80 m/det
decrease to downstream direction.The water depth was ranging from 19.9 to 49.8
cm tend to increase downstream direction. Total suspended solid (TSS) was
ranging from 8.5 to 14.2 mg/l and tend to be higher in the central city of
Yogyakarta. Dissolved oxygen concentration was 6.0-7.2 mg/l while CO2 was
0.7-1.9 mg/l. Organic matter was 22.8-25.1 mg/l and pH was in the range of
neutral. The density of macroinvertebrate was 88 individual/m2, the taxa number
in each station was 7-12 species, diversity index was 1.48-2.09, evenness index
0.76-0.85 and dominance index was 0.10-0.27, and there was not found dominance
organism among the stations samplings. The highest density was Limnaea
tranculata and Potamopyrgus jenkinsi. Index biotic family ranging from 5.95 to
6.64 showing the water environment was poor and there has been pollution caused
by garbage disposal of communities surround the river also waste disposal from
resident along the watershed.
Keywords: index biotic,
makroinvertebrate, pollution, Gajahwong
Penulis: Djumanto, Namastra Probosunu,
Rudy Ifriansyah
Kode Jurnal: jpperikanandd130667