Investigation of flow field in bays of Sanriku coast

Fiscal Year

2014

Title

Project and Theme

Project 1. Study on ecological succession of fisheries ground

Representative Organization: Tohoku University

Theme1. Environmental monitoring in coastal sea areas of Miyagi Prefecture

Representative person	Yoshinari Endo
Organization	Tohoku University
Department	Graduate School of Agricultural Science

Research Information

Period and Interval

2014/04/01 - 2015/03/31
once a year - evey month

Research Area

Onagawa Bay, Shizugawa Bay, Oppa Bay, Kesennuma Bay
0081_R01_map00.pdf

Overview

To examin restoration process of marine and fishing ground environments after the disaster, current measurements and water quality surveys are carried out in bays of Sanriku coast. These measurements and surveys will let us understand the flow field in the bays and the influence of the flow field on spatio-temporal variations of the marine and fishing ground environments there.

Overview of the Observation

Research Point Table

Point

Name	os.01
Coordinates	38.404082,141.535657
Name	os.10
Coordinates	38.441667,141.508333
Name	os.11
Coordinates	38.431717,141.5
Name	os.12
Coordinates	38.42568,141.5
Name	os.13
Coordinates	38.419212,141.5
Name	os.14
Coordinates	38.411305,141.4815
Name	os.15
Coordinates	38.402972,141.474833
Name	os.16
Coordinates	38.419212,141.4815
Name	os.17
Coordinates	38.42568,141.4815
Name	os.18
Coordinates	38.431717,141.4815
Name	os.19
Coordinates	38.434638,141.468167
Name	os.02
Coordinates	38.409218,141.533405
Name	os.20
Coordinates	38.441305,141.458167
Name	os.21
Coordinates	38.41165,141.526081
Name	os.31
Coordinates	38.44333,141.45
Name	os.32
Coordinates	38.44167,141.45333
Name	os.33
Coordinates	38.44282,141.45442
Name	os.34
Coordinates	38.44397,141.4555
Name	os.35
Coordinates	38.44332,141.45992
Name	os.36
Coordinates	38.44131,141.45817
Name	os.37
Coordinates	38.4399,141.45681
Name	os.38
Coordinates	38.43908,141.45796
Name	os.03
Coordinates	38.419212,141.530583
Name	os.39
Coordinates	38.4379,141.45966
Name	os.40
Coordinates	38.43965,141.46131
Name	os.41
Coordinates	38.4414,141.46296
Name	os.42
Coordinates	38.43907,141.46637
Name	os.43
Coordinates	38.43791,141.46516
Name	os.44
Coordinates	38.43675,141.46394
Name	os.45
Coordinates	38.43561,141.46273
Name	os.46
Coordinates	38.43444,141.46151
Name	os.47
Coordinates	38.43655,141.4617
Name	os.48
Coordinates	38.43834,141.46469
Name	os.04
Coordinates	38.426697,141.528208
Name	os.49
Coordinates	38.44365,141.4519
Name	os.50
Coordinates	38.44426,141.45804
Name	os.51
Coordinates	38.43966,141.46395
Name	os.52
Coordinates	38.43885,141.46339
Name	os.53
Coordinates	38.4379,141.46223
Name	ss.01
Coordinates	38.665298,141.456312
Name	ss.02
Coordinates	38.659133,141.456312
Name	ss.03
Coordinates	38.650632,141.456312
Name	ss.04
Coordinates	38.650632,141.470328
Name	ss.05
Coordinates	38.659133,141.470328
Name	os.05
Coordinates	38.434925,141.525833
Name	ss.06
Coordinates	38.668333,141.470328
Name	ss.07
Coordinates	38.672188,141.484343
Name	ss.08
Coordinates	38.66578,141.484343
Name	ss.09
Coordinates	38.659139,141.484343
Name	ss.10
Coordinates	38.649395,141.484343
Name	ss.11
Coordinates	38.643168,141.502362
Name	ss.12
Coordinates	38.65006,141.500293
Name	ss.13
Coordinates	38.659068,141.497588
Name	ss.14
Coordinates	38.66578,141.495573
Name	ss.15
Coordinates	38.669952,141.49432
Name	os.06
Coordinates	38.419212,141.516495
Name	ss.16
Coordinates	38.672188,141.493648
Name	ss.17
Coordinates	38.659617,141.468683
Name	ss.18
Coordinates	38.646282,141.493353
Name	ss.19
Coordinates	38.670262,141.477337
Name	ss.20
Coordinates	38.650632,141.46332
Name	op.01
Coordinates	38.573747,141.476147
Name	op.02
Coordinates	38.57857,141.488347
Name	op.03
Coordinates	38.573747,141.488347
Name	op.04
Coordinates	38.565608,141.488347
Name	op.05
Coordinates	38.582605,141.500095
Name	os.07
Coordinates	38.426697,141.516667
Name	op.06
Coordinates	38.573747,141.500095
Name	op.07
Coordinates	38.564517,141.500095
Name	op.08
Coordinates	38.556198,141.50248
Name	op.09
Coordinates	38.545045,141.500095
Name	op.10
Coordinates	38.591597,141.516667
Name	op.11
Coordinates	38.582605,141.516667
Name	op.12
Coordinates	38.573747,141.516667
Name	op.13
Coordinates	38.564618,141.516667
Name	op.14
Coordinates	38.591597,141.533333
Name	op.15
Coordinates	38.582605,141.533333
Name	os.08
Coordinates	38.434182,141.516493
Name	op.16
Coordinates	38.573747,141.533333
Name	op.17
Coordinates	38.564823,141.533333
Name	op.18
Coordinates	38.556198,141.533333
Name	os.09
Coordinates	38.441667,141.516667

Results and Future Plan

We have examined oceanographic condition in bays of Miyagi Prefecture in the Sanriku Coastal Area. As a result, many new findings have been uncovered, and our results are summarized as follows: 1. Phytoplankton spring bloom was accompanied by approach of the Oyashio water, which intrudes into the bays every spring. After the phytoplankton spring bloom, dissolved oxygen levels were reduced in the bottom layer during the period from summer to fall. These are typical features of seasonality in the oceanographic condition. 2. The dissolved oxygen levels in the bays during the period from summer to fall varied interannually; that is, the dissolved oxygen levels in 2014 were lower than those in 2013. 3. Short-term water temperature fluctuations with periods shorter than 30 days occurred in the bays during the period from summer to fall. It is considered that these short-term water temperature fluctuations are mainly caused by intrusions of oceanic waters into the bays. 4. In Onagawa Fishery Port, the tidal current tended to become small during the period from May 2013 to February 2014. There is a possibility that the decrease in the tidal current speed is caused by effects of the repair-works of breakwaters. 5. In Oppa Bay, nutrients originating from the land were supplied from a river, and the supplied nutrients were transported by estuarine circulation. The nitrate concentration was relatively deficient in comparison with the phosphate one based on the Redfield ratio, and the phosphate is a limiting factor for the production of lower trophic level in the surface layer.

Investigation Item and Data Acquisition

Investigation Item	Data Acquisition
current measurement	current direction and speed
survey of water quality	water temperature, salinity, turbidity, dissolved oxygen, chlorophyll a

Reference

Related Observation Plan

FY2014 Investigation of flow field in bays of Sanriku coast

Related Observation Data

Person in charge of Investigation

Representative person	Daisuke Takahashi
Organization	Tohoku University
Department	Graduate School of Agricultural Science

Keywords

Fiscal Year	2014
Organization	Tohoku University
Category	Field survey
Research Area	South Sanriku
Discipline	Ocean physics -> Water temperature Ocean physics -> Salinity Ocean physics -> Ocean current / Tidal current (Current direction/Current speed) Ocean chemistry -> Dissolved oxygen Ocean environment -> Plant pigments Ocean environment -> Others

Investigation of flow field in bays of Sanriku coast

Fiscal Year

Title

Project and Theme

Project 1. Study on ecological succession of fisheries ground

Theme1. Environmental monitoring in coastal sea areas of Miyagi Prefecture

Research Information

Period and Interval

Research Area

Category

Overview

Overview of the Observation

Research Point Table

Results and Future Plan

Investigation Item and Data Acquisition

Reference

Related Observation Plan

Related Observation Data

Person in charge of Investigation

Keywords