Environmental conditions related to community structure of macrozoobenthos in Belumai River District of Deli Serdang, North Sumatera Province.

Abstract

Belumai River is one of the rivers in Deli Serdang Regency, North Sumatra Province. Activity along Belumai River basin includes the activity of industrial, domestic and agricultural activities. The Belumai River used by some people for bathing, washing, toilet (MCK). People who use the river water susceptible of contracting diseases including skin irritation and eye irritation. Belumai River environment has a very important component of people lives around the river. Increasing of development activities such as input from industrial waste, urban sewage and runoff of agricultural water carried by the currents have an impact on water quality degradation Belumai River. The high activities have affected the composition and abundance of species makrozobentos in the Belumai River. Only those species that are tolerant of the environment can still survive. The purpose of this research is to analyze the relationship environmental conditions with community structure of macrozoobenthos. This research was conducted in Belumai River Deli Serdang Regency, North Sumatra Province, on 4 stations for 3 months, with a time interval of 1 month. Determination of the station, based on consideration of the different input load from any location, thus defined three sub-districts into the sampling site, which is 1 station in the district of STM Hilir, station 2 and station 3 in the District of Tanjung Morawa, and 4 station in the District of Batang Quiz. Samples collected consisted of physical parameters, namely temperature, currents, depth, turbidity, and type substrate. Chemical parameters namely pH, DO, COD and TOM. Macrozoobenthos was collected as biological parameter. Macrozoobenthos were found during research in Belumai River consists of 3 classes (gastropods, insects and Oligochaeta). Station 1 genus number obtained during the observation that there are 5 genera : Branchiura sp., Chironomus sp., Lumbricus sp., Melanoides sp., and Bellamya sp. Station 2 genus number obtained during the observation that there are 4 genera : Branchiura sp., Lumbricus sp., Limnodrilus sp., and Goniobasis sp. Station 3 genus number obtained during the observation that there are 5 genera : Branchiura sp, Lumbricus sp., Limnodrilus sp., Goniobasis sp., and Tubifex sp. Station 4 genus number obtained during the observation that there are 6 genera : Branchiura sp., Lumbricus sp. , Limnodrilus sp., Goniobasis sp., Chironomus sp., and Goniobasis sp. Type uniform distribution of each station is visible from the class Oligochaeta Branchiura sp., and Lumbricus sp. The percentage of the composition of each class is the Oligochaeta 79%, Gastropoda 17%, and Insects 4%. Oligochaeta has the highest percentage with 79%. The high percentage indicates the existence of a class Oligochaeta Belumai River has been polluted. Oligochaeta are a tolerant organisms and able to withstand environmental conditions containing high organic matter. Diversity of macrozoobenthos in Belumai River based on analysis of k-dominant curve shows that the diversity decreases in the downstream direction. seen from the station groupings based on the analysis of Bray-Curtis Dissimilarity for macrozoobenthos and Pearson for physico-chemical parameters, resulting in two dendrogram which shows similarities. Both the dendrogram showed distinct groupings that station 1 to station 2, 3, 4. The existence of these groups due to differences in the input of pollutants from residential, industrial, and urban. The results of chemical physics parameters in the River Belumai were : temperature (28 - 29 o C), depth (2,5 - 3,1 m), current velocity (0,31 - 0,58 m / s ), Turbidity (163,57 – 242,60 NTU), pH (6,6 - 6,9), DO (6,6 - 7,01 mg / L), COD (35,64 - 42,01 mg / L), and TOM (14,72 -15,90 %). There was shows that turbidity was very high caused supposed it by input from the upstream as the activities around the river into the water through rain water seepage. Organic content as seen from COD value has exceeded the threshold limits for drinking water (class 1), according to Governmant Regulation (PP) No. 82/2001, has passed the threshold exposure limits for class 1 is allowed COD content of <10 mg/L. The high value of COD in water was almost certainly come from contaminants that enter the waters, i.e. organic pollutants from domestic sewage, industrial, agriculture and aquaculture waste.