Phosphorus finger prints of Lake Semayang

A study to examine phosphorus finger print of Lake Semayang was conducted between July 1996 to January 1998. The objective of the study is to gather data bases on the relationship of terrestrial detritus input to fishery production. A Phosphorus finger print study can indicate the material input, trophic status, detritus dependency and organic distribution of aquatic systemt. Direct measurements of parameter and water sampling were done in four. stations. Chemical analyses of phosphorus species are conducted according to the method described in Standard Methods (1992). pH, water temperature and dissolved oxygen in monsoon season are decreasing according to increasing depth. Total-P concentration decreased from 675.2 ug/l in the dry season to 52.2 ug/l in rainy season due to dilution process. The results of finger prints for material input and trophic indicator examination indicate that Lake Semayang change from autochthonous lake in the dry season to allochthonous in rainy season. Results of production rate finger print indicate that primary production seemed to be control by the balance of wind scouring effects of the wind and orthophosphate sedimentation process of aerobic water. The organic material level of the lake also change from the one that are determined by wind scouring effects in the dry season to more detritus dependent in rainy season. Percentage of dissolved organic phosphorus is always high probably due to due to advanced fragmentation of organic detritus