낙동강 하굿둑 개방으로 인한 먹이망 영향 예측

Predicting the Impact of the Opening of the Nakdong River Estuary Barrage on the Ecosystem Food Web

In the several decades since the barrage at the mouth of the Nakdong River estuary was built in 1987 for water supply and salinity control, the water mass inside the barrage has become polluted and the ecosystem has shrunk. To restore the health of the ecosystem, fishery resources and biodiversity, stakeholders who currently use the estuary are calling for the barrage to be opened, which has been partially accomplished. In this study, trophic flow foodweb models are applied to understand the food web structure and functions of the Nakdong River estuary ecosystem and forecast the effects of barrageopening. The model results showed that; 1) Ecological theory and cycling indices of Total System Throughput 5457 t km-2 y-1, Primary Production/Total Respiration 2.0, PP/ Biomass 34.9 y-1 and B/TST 0.010 y-1 indicate that the ecosystem is not fully developed and vulnerable to external perturbation. 2) A Transfer Efficiency of 2.6% between TL II-IV indicates low predation pressure and/or excess nutrients and detritus being supplied to the lower trophic level but not ultimately transferred to higher trophic levels, as is generally the case in polluted ecosystems. 3) Macrophytes appear to be able to provide food for benthic organisms in the form of organic detritus, and the effects of opening up the lower bank on macrophyte communities may feed through the food web to higher trophic levels. 4) As this study is for the purpose of a pilot model based on a limited range of reliability in the basic data and salinity-response relationship data, although it reproduced relatively stable distributions along the estuary, caution is needed in interpreting the model results. The pilot model developed in this study is expected to provide a useful basis for analyzing the food web and predicting and managing the effects of opening the estuary in the future.