Sargassum at Tsuyazaki— -Yoshida, Saw ADA, and Higaki 
137 
°c 
Fig. 3. Seasonal variation of surface temperature 
(solid line) and specific gravity (dotted line) of the 
sea water for I960, measured at the top of the break- 
water for the port of Tsuyazaki. 
posed to wave action. The eastern sides of Sone- 
no-hana and Kyodomari are more sheltered 
from wave action, although there is no method 
of determining the strength of wave action, 
judging from the results of direct observation 
of waves and from the characteristics of the in- 
tertidal algal zonation. 
The tidal current is faster where the shore is 
more exposed to wave action, and vice versa in 
the area surveyed. 
Surface temperatures rise to about 28 C in 
August and descend to about 10 C in January 
(Fig. 3). Transparency of the sea water is less 
than 15 m in the Secchi disc reading almost 
throughout the year. After a heavy rain, low 
transparency is sometimes recorded around 
Sone-no-hana. 
METHODS 
Field surveys were carried out during 7 days 
between July 23 and August 26, 1959, on 13 
survey lines In the area (Fig. 4), as follows. A 
survey ship was anchored at the offshore end of 
each line. A rope was then strung from the ship 
to a rock on the shore. Survey spots were se- 
lected along the rope every 5 or 10 m depend- 
ing on the inclination of the bottom. One or 
two observers, a recorder, and a crew got into a 
small boat. The boat halted at each survey spot. 
The depth of water was measured with a sound- 
ing lead and then a quadrat was laid down. The 
quadrat used in this study was a 0.5 m square 
iron frame. Observations on the plants found in 
the quadrat were made by skin diving, using a 
face mask only. First, the percentage of vegeta- 
tional cover of the area around the quadrat was 
recorded. Then, the degree of cover by each 
species of the algae present in the quadrat was 
measured. The scale for the measurement of 
cover degree was as follows : 
+ 0 - 10 % 
1 11 - 20 % 
2 21- 40% 
3 41- 60% 
4 61- 80% 
5 81-100% 
Number and height of the plants were recorded 
when this was possible. The species not present 
in the quadrat but found in the surrounding 
area were also noted. 
The number of quadrats placed along each 
Fig. 4. Map of Tsuyazaki peninsula, indicating the 
13 survey lines. 
