Stream ecology of the Kali Dinoyo, East Java, Indonesia

Mike Grace, Chris Walsh, Sandra Sdraulig and John Gooderham of the CRC for Freshwater Ecology conducted an eight-day workshop on the ecological assessment of rivers at the University of Jember (UNEJ) in July 1998.  Twenty-five staff and student from universities and government organizations throughout East Java attended.  The workshop was funded by the intergovernmental Targeted Institutional Links project.  Basic concepts of riverine ecology and ecological study design were covered in the workshop, with an emphasis on the importance of multi-disciplinary approaches.

The participants put principles into practice by devising, planning, conducting and analysing a small project.  They investigated the impact of a village and its associated coffee processing plant (set within a coffee plantation) on the upland Kali (River) Dinoyo, about one hour north of Jember. Water quality, habitat quality and macroinvertebrate community structure were assessed. Two sites were sampled in the coffee plantation, one upstream and one downstream of the village, and a further two sites were sampled in the rainforest upstream of the plantation.

Some minor effects of the village were evident (e.g. a small increase in suspended solids downstream of the village).  However, the majority of variation among the sites for most variables was explained by differences between the rainforest and plantation sites (plantation sites had higher nutrient concentrations and more variable macroinvertebrate community structure).  Although this was not conclusive evidence of the effect of the plantation (this was not the question the study was designed to answer), it was suggestive of such an effect.  These results demonstrated to the participants the potential importance of diffuse source effects on riverine ecosystems.

The participants produced a report on the project (in Bahasa Indonesia), which was the basis of two papers presented at the TIL conference in Lombok in October 1998 (Grace et al. 1998, and Gooderham et al. 1998).  John and  Imron Rosyidi of UNEJ returned to the Kali Dinoyo in October 1998 to collect a second set of macroinvertebrate samples and a set of diatom samples: this extra work resulted in a refereed publication.

Walsh, C. J., Gooderham, J. P. R., Grace, M. R, Sdraulig, S., Rosyidi, M. I. and Lelono, A. (2002).  The relative influence of diffuse- and point-source disturbances on a small upland stream in eastern Java, Indonesia: a preliminary investigation. Hydrobiologia 487, 183-192.

Abstract

Macroinvertebrate community composition and water quality were assessed in four sites along Kali Dinoyo, a small upstream stream in East Java, Indonesia.  The catchment of the two most-upstream sites were covered primarily by rainforest, while the two lower sites fell within a coffee plantation, the lowest downstream of a small village and its associated coffee-processing plant.  Most of the variance in all water quality variables and in several community composition measures was explained by the difference between plantation and forest sites.  Comparatively small differences in total suspended solids and macroinvertebrate community composition were observed downstream of the village.  Diffuse disturbances associated with land clearance and plantation agriculture therefore appear to have a larger impact on the ecology of Kali Dinoyo than the point source impacts associated with the village.  More robust and powerful study designs to formally test these findings are discussed.