Abstract
In order to evaluate the influence of shellfish farming on water quality, a hydrodynamical and
ecological coupled model was applied to Chinhae Bay. We compared results of simulations that
included and excluded the presence of farmed shellfishes.
From the hydrodynamic simulation, Chinhae Bay has a calm current system except at the
mouth. Bay water exchanges with open sea water through the Caduk and Central channels.
From the simulation that included farmed shellfishes, it was estimated that shellfishes ingested
34% of phytoplankton primary production (including zooplankton and detrital matter), and egested
70% of that organic matter in the form of fecal pellets. Thus according to the simulation,
farmed shellfishes reduced the standing stocks of phytoplankton, zooplankton, and POC from
water throughout the Bay by 325 tons, 19 tons, and 821 tons respectively. The phytoplankton
biomass in this simulation reduced the organic matter the produce which also means a low COD
value (concentration). In contrast, amounts of DIN and DIP increased to 508 tons and 50 tons
respectively, through fecal pellets excreted by the shellfishes. The nutrient flux from the sediment
also increased as a restul for these pellets depositing on the sea bed. For example, the DIN and
DIP flux from the sediment were approximately 10 and 2 times higher than simulations run ex
cludingshellfishes. Based on these simulation results, it appears that shellfishfarming has a great
impact on the coastal ecosystem.
