Effect of Aquaculture on Material Cycles in Otsuchi Bay, Japan

A numerical physical-biological coupled model is developed for the study of coastal material cycles including aquaculture. The model calculates spatial distributions of PON (Particulate Organic Nitrogen), POP (Particulate Organic Phosphorus), DON (Dissolved Organic Nitrogen), DOP (Dissolved Organic Phosphorus), Chl-a, zooplankton, NO_3-N, NH_4-N and PO_4-P using simulated current. It also takes into consideration the effects of shellfish feeding and excretion, seaweed photosynthesis, and the loading of DIN from rivers. The model is applied to Otsuchi Bay, in Iwate Pref., in Japan. The model elucidated the cycling of nitrogen among ecological compartments. If the amount of cultured shellfish is extremely increased, the feeding by shellfish is large enough to change the lower trophic level ecosystem, reducing concentration of phytoplankton and POM (Particulate Organic Matter) around the cultured region, while phytoplankton increases far from the culture due to the increase of recycled nutrient by the excretion of shellfish

How do we know salmon behavior ? : II. A mesoscale study : Behavior of salmon schools estimated from fish market statistics and routine marine meteorological data.

Abstracts of the UNU and ORI joint international workshop for marine environment in 2000海洋環境国際ワークショップ（大槌, 2000年2月21日～25日）の講演要

Comparison of the currents measured by electromagnetic current meter and bottom mounted ADCP in Otsuchi bay

Near-surface current data obtained by bottom-mounted Acoustic Doppler Current Profilers (ADCP) are compared with those by electromagnetic current meter (ACM) in Otsuchi bay, Sanriku ria coast in northern Japan during the two periods from October 2003 to March 2004 and from April to October 2004. Although near-surface data obtained by upward looking ADCP is affected by the acoustic beam reflected from the sea surface, the results show that those data have significant correlation with each other. This means that bottom-mounted ADCP is useful for estimating the transport from the sea-surface to bottom

Estimation of water circulation in Otsuchi Bay, Japan inferred from ADCP observation

In order to understand the seasonal water circulation system of Otsuchi Bay, direct current measurements were taken by using bottom-mounted Acoustic Doppler Current Profilers (ADCPs) during two periods, from October 2003 to March 2004 and from May 2004 to October 2004. During the first observation period, a remarkable estuary-type vertical circulation was observed. An anti-clockwise circulation, flowing into the bay along the northern coast and out along the southern coast was dominant during the second observation period. It was found that this clear seasonal variation was generated by both seasonal changes of wind and tide-induced residual current

Estimation of water circulation in Otsuchi Bay, Japan inferred from ADCP observation

In order to understand the seasonal water circulation system of Otsuchi Bay, direct current measurements were taken by using bottom-mounted Acoustic Doppler Current Profilers (ADCPs) during two periods, from October 2003 to March 2004 and from May 2004 to October 2004. During the first observation period, a remarkable estuary-type vertical circulation was observed. An anti-clockwise circulation, flowing into the bay along the northern coast and out along the southern coast was dominant during the second observation period. It was found that this clear seasonal variation was generated by both seasonal changes of wind and tide-induced residual current

Effect of Aquaculture on Material Cycles in Otsuchi Bay, Japan

A numerical physical-biological coupled model is developed for the study of coastal material cycles including aquaculture. The model calculates spatial distributions of PON (Particulate Organic Nitrogen), POP (Particulate Organic Phosphorus), DON (Dissolved Organic Nitrogen), DOP (Dissolved Organic Phosphorus), Chl-a, zooplankton, NO_3-N, NH_4-N and PO_4-P using simulated current. It also takes into consideration the effects of shellfish feeding and excretion, seaweed photosynthesis, and the loading of DIN from rivers. The model is applied to Otsuchi Bay, in Iwate Pref., in Japan. The model elucidated the cycling of nitrogen among ecological compartments. If the amount of cultured shellfish is extremely increased, the feeding by shellfish is large enough to change the lower trophic level ecosystem, reducing concentration of phytoplankton and POM (Particulate Organic Matter) around the cultured region, while phytoplankton increases far from the culture due to the increase of recycled nutrient by the excretion of shellfish