Spatial Diversity of Macrobenthic in Ngenep Spring Due to Anthropogenic Activities

This aims of this study are to determine the macrobenthic community structure between the drainage near residence and spring; and to determine effect of local environment on macrobenthic community structure at the Ngenep village. Field study was conducted in 3 drainage, i.e. residential drainage, spring and rice field irrigation. Macrobenthic were sampled by the surber net and hand net in three stations in each drainages. Abiotic factors were assessed at the same stations. Macrobenthic community structure and diversity was determined using Important value index, ShannonWiener index and Bray Curtis index. Cluster of benthics and abiotic factors were analysis using Principal Component Analysis (PCA). Abiotic data showed no statistical significance in 3 drainage (P>0.05) but showed increasing trend from spring to field irrigation and the highest at residential drainage. The 17 taxa of macrobenthic were found with high important value index are Melanoides tuberculata, larva’s of Ephemeroptera and Plecoptera. Highest Shannon-Wiener index observed at irrigation (2.781). The cluster analysis of abiotic factor showed that spring was in different cluster with residential and irrigation, meanwhile, PCA analysis of macrobenthic showed each place was different cluster. Conclusion of this study is anthropogenic activities alter the diversity and community structure of macrobenthic.


INTRODUCTION 
Ngenep villages, Malang Regency, East Java, Indonesia have a spring and the water is utilized for many things.Most of the citizen in Ngenep are farmers (3,911 people from 13,499 people) and use the water for agricultural purposes and daily purposes such as bath and laundry [1].Anthropogenic activities in Ngenep village may alter the water quality.Bioindicator organism, such as plankton, benthic macroinvertebrates or fish may be employed to assess the aquatic commu-nity quality and water quality.Benthics are effective tools for environment health assessment; these are easy, cost-effective, and quick assessment [2].
Macrobenthic are the organism that dwells in the bottom of the water body.These organisms have role in water mineralization process, assist the water organic material cycle, and become the linking chain between plankton and peryphiton to higher tropic level in aquatic community.Many studies used macrobenthic as the bioindicator of water quality because of its relatively easy to conduct, inexpensive, and because of its limited migratory pattern able to give better water quality assessment.Anthropogenic land-based activities such as urban runoff were  Correspondence address: Ekwan N. Wiratno Email : ekwanwiratno@gmail.comAddress : Jl.Veteran Malang 65145, Malang.
given impact on the distribution and species diversity of macrobenthic invertebrates [2].
Ngenep are one of the most spring sites at Malang and near human residence.
The aims for this study are to determine the community structure of the macrobenthic between the drainage that built near the residence and spring; and to determine the effect of local environment to macrobenthic community structure.The data of the study are expected as the reference to water remediation and conservation management for near human dwellingwater bodies.

MATERIALS AND METHODS Study Sites and Benthic Sampling
Ngenep Village, Malang City is located at 7°44'-8°26'LS and 112°17'-122°57'BT with highland topography at 250-500 m asl elevation.The study was conducted in November 2013.Field study was conducted in 3 drainages; (1) the stream of drainage near the human residence, (2) the stream near the spring and (3) the stream near the field irrigation.The spring is the source of water in the drainage.
Macrobenthic was sampled using surber net and hand net in 3 stations, based on selective sampling, which categories are substrates differences and riparians.Collected macrobenthic was sorted using pinset and white plate and then preserved with 70% ethanol in labeled sterile vials.Identification is conducted in Ecology Spatial Diversity of Macrobenthic in Ngenep Sprinng (Wiratno et al.) and Animal Diversity Laboratory at Department of Biology, University of Brawijaya using the stereo microscope and reference literature [2,3,4].

Abiotic Factor Measurements
Abiotic factors are measured at the same stations and triplicate.The measured factors are: water temperature (°C) using thermometer; stream velocity (m.s -1 ); conductivity (µ mhos) using conductivity meter; water pH using digital pH meter; Dissolved oxygen (DO) (mg.L -1 ) using digital DO-meter [4,5], DO data were used to measure the water BOD; Total Organic Matter (TOM) [6]; water turbidity using turbidity meter; water nitrate content (mg.L -1 ) method [7]; and water orthophosphate content (mg.L -1 ) method [8].We also slightly described the stream substrate using direct observation.

Data Analysis
Macrobenthic community structure is determined using: (1) Important value index to determine the relative importance of each species; (2) Shannon-Wiener index to estimate the community diversity; and (3) Bray Curtis index to estimate the dispersal and similarity of macrobenthic [5,9].Principal component analysis (PCA) for abiotic factor and macrobenthic were employed with PAleontological STatistics (PAST) program.ANOVA analysis is employed using SPSS 16.0 for Windows.

RESULT AND DISCUSSION Abiotic Factor
The abiotic data from three water bodies showed no significant differences (P>0.05) for almost the entire factor.The only difference was water at residential drainage have faster velocity than the other (Suppl.1).Although the abiotic factors have no statistical differences, there are some trends that occur.DO, BOD, conductivity, TOM, and turbidity have increasing pattern from spring to field irrigation and the highest at residential drainage.Cluster analysis and PCA showed that irrigation and residential drainage have very high similarity (93%) (Suppl.2) and it became the same cluster with 80% threshold.It suggested that the spring have different quality, and anthropogenic activity may one of the causes.Biplot of PCA showed that many abiotic factors have tendency to the irrigation and residential cluster.Nitrate content is highly positive correlated to irrigation.Water debit is positively correlated to water spring (Fig. 1).
Anthropogenic activity near the spring does not have considerable impact based on the abiotic data.The increasing trend of DO, BOD, conductivity, TOM, and turbidity are mediated by anthropogenic activity, but no significant (P> 0.05).Increased conductivity is result of human impacts such as organic pollution and nutrient enrichment [10].Turbidity usually goes around with conductivity patterns [11].
Shannon Wiener diversity index value showed that every water bodies have value more than 2, which is considered good.The community stability in the three places is not easy to change if there are slight disturbances from the environment.Lower diversity index in water spring may caused by the substrate.Most of the substrate at the water spring are sand, meanwhile the others are rocky and slight sand.Sandy environment have less diversity than rocky, and most of them are suspended feeder or carnivores such as Polychaeta, Bivalvia and Crustaceas [12].We found many M. tuberculata (Bivalvia) in spring.
Cluster analysis using Bray Curtis Index and principal component analysis (PCA) were conducted to determine the dispersal of the macrobenthic (Fig. 1).The data showed that three water bodies have different macrobenthic based on 80% similarity and become three different clusters (Suppl.3).The data suggest that antrophogenic activity alters the macrobenthic community stronger than the abiotic factor.
The oxygen concentration was the most important factor for Ephemeroptera, Coleoptera, Trichoptera, Hemiptera, Odonata, Diptera and Hydropsychidae.The BOD was the most important factor for Hydrophilidae and Hirudinea, whereas the turbidity for Collembola [13].The water spring have the lowest DO between the three and have less Ephemeroptera.

CONCLUSION
The 17 taxa of macrobenthics were found with high important value index are Melanoides tuberculata, larva of Ephemeroptera and Plecoptera.The high observed Shannon-Wiener index was observed at irrigation (2.781), resident drainage (2.554) and spring (2.064).PCA analysis of abiotic factor showed that spring was in different cluster with residential and irrigation, meanwhile, PCA analysis of macrobenthic showed that each place has different cluster.Anthropogenic activities alter the diversity and community structure of macrobenthic.

Figure 1 .B
Figure 1.PCA Analysis of Abiotic Factor and Macrobenthic of 3 Water Bodies at Ngenep Village A: Abiotic Factor; B: Macrobenthic

Figure 2 .Figure 3 .
Figure 2. Important Value of Macrobenthic in three types of drainage at the Ngenep Village