The floating seaweeds were surveyed on the sea between Hakata and Tusima Island, northern Kyushu, for 12 times from January to December, 1959. The number and estimated weight of the floating seaweeds were recorded every minutes, using the method that had been employed previously. The unit survey area along the courses of the ship was, therefore, 10 m wide and 320 ?380 m long according to the speed of the ship concerned . The results are summarized as follows : 1. Total estimated weight of the floating seaweeds observed varied seasonally, and the largest amount was observed in June. 2. The estimated amount of the floating seaweeds per unit area observed in Iki Passage in June was nearly the same with that of the Sargasso Sea reported by Parr (1939). 3. Distributional pattern of the floating seaweeds was very contagious throughout the year judging from Is value proposed by Morisita (1959). Analysis of clump size for February, April, June, and August showed that rather small clumps (ca. 0.6-3 km) and larger ones (about 20 km) were present except in June when clump size was somewhat indefinite.
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