Study on the environmental improvement in Nakagusukuwan Port Awase
AreaThis study was conducted in relation to the identification of the environmental conservation and monitoringmeasures for constructing a dredged material disposal site under the direct control of the Ministry of Land,
Infrastructure, Transport and Tourism in the Awase area in Nakagusukuwan Port. Deliberations and analysis
were made concerning the project implementation, the results of environmental monitoring and theconservation of seaweeds and algae, based on the opinions of experts.
Various deliberations were made in the fields related to this study based on the opinions of the committees andpanels staffed with the persons of learning and experience listed below.

Review organizations in the Awase area in Nakagusukuwan Port
Environmental conservation and creation committee

Environmental monitoring committee
Artificial beach nourishment panel

Seaweeds and algae panel
Environmental use teaching panel

Artificial island environmental
improvement panel…Committees and panels making
deliberations in this study…Panels currently making deliberations

Hiyane marsh and Awase area
coastal improvement panel…Panels that have completed deliberations

Figure 1 Correlations among review organizations
In this study, guidance was received on environmental conservation measures from the environmental
conservation and creation committee and the seaweeds and algae panel. The results of environmental
monitoring were reported to theenvironmental monitoring committee for evaluation.

In the seaweeds and algae panel, proposals were made concerning the "transplant of large seaweeds", one of
the environmental conservation measures, and reports were submitted and proposals were made concerningthe "creation of a field" for improving transplant techniques.
A list of conditions for the inhabitation of kubiremidoro (Pseudodichotomosiphon constricta), one of theendangered species, was presented based on the results of various tests and the analysis of relations between
the oceanographic conditions and the growth of the species.

11. Study items(i) Deliberation on the results of environmental monitoring(ii) Deliberation on the transplant of seaweed beds(iii) Deliberation on the plan for creating a field(iv) Deliberation on the conservation of kubiremidoro<refrect in studyand deliberation>(v) Preparation of committee materials(vi) Preliminary meeting for conference(vii) Briefing for committee chairpersons and others(viii) Holding of a committee meeting(iv) Disclosure of information

Figure 2 Flowchart of study steps
2. Method of study(i) Deliberation on the results of environmental monitoring
The results of environmental monitoring were organized. The results were compared with the designatedcriteria. In the case where the results failed to meet the criteria, the effect of construction was deliberated.
(ii) Deliberation on the transplant of seaweed beds
A comparative study was made of the density of transplanted seaweeds and the obtained knowledge wasorganized. Sediment surveys were proposed that were required for organizing the knowledge.
(iii) Deliberation on the plan for creating a field

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The state of growth and the environmental conditions such as the growth of seaweeds, oceanographic
conditions and the effects of typhoons were investigated in the tests for the "creation of a field" for improving
transplant techniques. Deliberations were made on the expansion of habitat and the measures to extend
facilities.
(iv) Deliberation on the conservation of kubiremidoro
Laboratory culture tests and field tests in the Katsuren area were conducted to conserve kubiremidoro. The
relationship of waves and flow to the area of habitat, and habitat conditions based on the external forces wereorganized.
(v)

Preparation of committee materials through (iv) Disclosure of information

Based on the results of deliberations, materials were prepared for the committees and panels. The secretariat
conference meetings were held and committee chairpersons and others were briefed on the materials.
Committees and panels were held and operated, and data were developed for disclosure to the public.
3. Results of study(i) Deliberation on the results of environmental monitoring
In relation to the items that could not meet the criteria, a comparison was made with the range of variation
before construction (step 1), a comparison was made with the condition in the study area (step 2) and check
was made as to whether wide-area environmental changes occurred or not (step 3). As a result, no effect ofconstruction work was found. Monitoring items and the points of monitoring are shown in Table 1 and Figure
3, respectively.

Table 1 Outline of monitoring
Item
Air quality ★

Carbon dioxide

1Benzene

1COD

4SS4All species

6

Noise and vibration ▲Water quality ●Bird species
Seaweeds ○kubiremidoro
Coral ■
Tokagehaze (Scartelaoshistophorus) ◆Brackish species in theHiyane marsh

Number ofmonitoring points

5

Snipe and plover

6

Coverage

7

Distribution
Area of distribution
Coverage
Number of species
Population of adult fish
Area of habitat
Diameter measurement

Frequency
Four times/year
Four times/year
12 times/year
Four times/year
Twice/year(Refer to Figure 3) Four times/year
3

Twice/year(Refer to Figure 3) Four times/year
5

Brackish water quality

2

Number of brackish species

2

Twice/year

Figure 3 Monitoring positions

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(ii) Deliberation on the transplant of seaweed beds
The following findings were obtained based on the results of studies conducted up to March 2006.
The coverage was once reduced after the transplant but has increased slightly up to the present. The coverageremained in the range of variationof natural seaweed beds before construction. The area and conditions ofhabitat were found generally satisfactory. Then, it was determined that the environment for reproduction oftransplanted seaweeds and the habitat were improved. As a result of comprehensive evaluation of thecondition three years after the transplant with respect to various items, it was found that the beds whereseaweeds were transplanted manually grew like natural seaweed beds. From a long-term viewpoint, the beds
seemed to be in progress of succession. Continuing monitoring was therefore considered important.

Figure 4 Coverage by growing seaweeds in the area of transplant

Figure 5 Area of growth in the area of transplant4(iii) Deliberation on the plan for creating a field (reporting of monitoring results)
A field was created for the conservationof the objectives of "transplant of largeseaweeds".
The waves and streams in thecreated field and the changes in groundevel elevation were identified and l thedata on the growth of transplanted seaweeds
were organized. Topographicalchanges werepredicted based on the wave onditions
during the latest typhoon c that passed thesite, and the location of embankments with

Figure 6 Growth of seaweeds andswarming of fish

a low crown height was proposed whenincreasing the scale of the test. The results of studies of the swarming of species, one of the secondary effects
of installation of embankments with a low crown height, were also reported.
(iv) Deliberation on the conservation of kubiremidoro
The habitat of kubiremidoro in the Awase area overlaps part of area II of the dredged material disposal site.
For improving the disposal site, kubiremidoro will be transplanted in the Yakena area and transplanted back to
an artificial tidal flat in the Awase area from the Yakena area upon completion of the flat. Laboratory culture
tests were conducted to establish propagation techniques for eliminating the risk of accidental extinction in thefield. The objective was to conserve kubiremidoro.

51) Laboratory culture tests for kubiremidoro
Kubiremidoro emerge from an egg, andbecome filamentous and finally algal.
Maturity
And egg
production

The life cycle was reproduced inaboratory
using a flask and a large waterl tank andDevelopmentof an algal
body

Aestivation

varying the water temperature,duration oflighting, intensity of illumination andnutrients in the state of an egg and during

Buddingbudding.

Growth of afilamentous
body

As a result, an egg and a filamentous
filamentous body were observed but noFlask and petri dishalgal body was found in the large watertank. In the flask, the egg, filamentous body

Large water tanks

and algal body were found. But no egg

Figure 7 Life cycle and achievements in culture test

produced from the algal body was observed.
Only antheridia were found.
Conducting field and laboratory tests in combination is required to establish basic seed production techniques.
2) Deliberation on the physical disturbance factors affecting the inhabitation of kubiremidoro
The correlation between the area of inhabitation of kubiremidoro and external forces such as winds and waves
was examined.
The coefficients of correlation of annual frequencies of high waves and strong winds to the area of
inhabitation in March, at the height of prosperity, were -0.76 and -0.91. This suggests that high waves andGrowing area
in March (m2)

18000

18000

16000

16000

14000

14000

3月の生育面積(m2)3月の生育面積(m2)strong winds have certain bearing upon the life of kubiremidoro.

Growing areain March (m2)

12000
10000
8000

y=17354-52.783x R=-0.76573

6000

y = 17354 - 52.783x

R= 0.76573(in times)

4000

12000
10000
8000

y=17052-87.623x R=-0.90663

6000

y = 17052 - 87.62x(in times)

R= 0.90663

4000
0

50

100

150

200

250

2040

60

80

100

120

140

Frequency高波浪出現頻度(前年3月～当年2月)，有義波高（H>3.0m）
of high waves (Mar. previous year throughFeb. current year). Significant wave height: 3.0 m.

Frequency強風出現頻度(前年3月～当年2月)，風速（V>10.0m/s）
of strong winds (Mar. previous year throughFeb. current year). Velocity: 10.0 m/sec.

Figure 8 Correlation between thefrequency of high waves
and the area of growth

Figure 9 Correlation between thefrequency of stroug winds
and the area gorowth63) Deliberation on the conditions for the inhabitation of kubiremidoro
The inhabitation of kubiremidoro has been confirmed in the Awase and Yakena areas in Nakagusukuwan Port.
The conditions for the inhabitation of kubiremidoro were identified by confirming the conditions in theseareas (e.g. ground level elevation, bottom materials, water quality and existence of small seaweeds).
Numerical analysis was made using the results of tests conducted using the stone masonry fences in theKatsuren area and the external forces in the habitat in the Awase area. As a result of comprehensive analysis,
the conditions for the inhabitation of kubiremidoro were identified (Table 2).

Table 2 Conditions for inhabitation of kubiremidoro
Item
Turbidity
Water
quality

Nutrient
Salt content

Ground level elevation

Grain size
Bottomdistribution
materials
Mineral composition
Small seaweeds

Change in groundlevel elevation
Oxidation reduction

Disturba

potentialncesTransport of sandEffects of winds andConditions for inhabitation
Required light may be secured by creating a small water depth so as to expose the bottom
during low water.
The level of nutrient required for the inhabitation of kubiremidoro seems to be available in
the Awase area.
Inflow of fresh water direct into the habitat should be avoided because little knowledge isavailable about the resistance of kubiremidoro to low salt content
Existing knowledge and field investigations show that kubiremidoro inhabit in a wide
range at 0.1 through 1.0 m above chart datum level. The range of elevations vary frompoint to point and is likely to be determined by the distribution of small seaweed beds.
Bottom materials are composed mainly of fine and medium sands and are mixed withgravel and mud in a wide area where kubiremidoro inhabit. Silt and clay are considered todeposit because of little disturbance to the bottom materials.
The percentage of quartz is slightly high in the places where kubiremidoro grow.
Kubiremidoro grow in the places where small seaweeds live. The existence of smallseaweeds seems to be contributing to the growth of kubiremidoro by controlling thetransport of sand and the washout of eggs.
The ground level elevation changed locally by a maximum of 20 cm due to typhoons.
Studies will be made based on the state of growth during the development of an algalbody.
The value is low in tranquil places where seaweeds grow because of no disturbances tobottom materials.
It has been found that the transport of surface sand is detrimental to the growth ofkubiremidoro. Important to the growth of kubiremidoro are the development of no sandripples and the control of sand transport in the surface area with a depth of a few
centimeters.
Disturbances to sand by waves in the bay seem to be affecting the growth of kubiremidoro

waves

External forces

Shields number, the ratio between the forces of waves or streams to move particles andthe resistance of particles, in the present habitat was calculated in numerical analysis as anindicator of external force. The Shields number should therefore be handled not as acondition for inhabitation but as a reference for selecting an optimum place or examining
the design.

7Step (v) Preparation of committee materials through step (iv) Disclosure of information
Based on the deliberations in (i) through (iv), materials were prepared for the committees and panels. The
chairpersons of the committees and panels were briefed on the materials in advance for detailed inspection,and the materials were presented to the committees and panels. The Environmental monitoring committee,
Environmental conservation and creation committee, Seaweeds and algae panel and Artificial island
environmental improvement panel had two meetings each. Materials were prepared for information disclosure
to the public.

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