Biosphere Sci. 49 31 38 (2010) 1,5 2 3 1 4 5 1 739-0452 2-17-5 2 JICA Niger 523 rue des lacs PL521 Quartier Plateau Commune 1 Niamey Niger 3 781-1164194 4 811-01143-9-4 5 739-8528 1-4-4 38 64 1005m red tide 1999 1 Leliaert et al., 2009 19991970 Uno et al., 1983 1999 1980 1 1999 2001 Uchimura et al., 2004 2002 Uchimura et al., 2004; Hiraoka and Yoshida, 2010 Uchimura et al., 2004 20m 2010 9 10
32 2002 2003 2002 1 2002 1 17 12 Fig. 1 4.9 2 1SCUBA 5 m4 cm4 m 40 cm Fig. 2a, b GPS 4 6 km / hr 200 400 m Table 1 D.L. 2.6 m 17.0 m 1 SCUBA St. B, St. E, St. K D.L. 2.0 m 50 cm Fig. 2 Table 1. Locations of the start and finish in trawl-net sampling (by WGS84), mean depth, distance of net-trawling and area of trawling at each station. St. Location Start of trawling Finish of trawling Mean depth (m) Distance (m) Area (m2) A Otake Oki N 34 14 52.9 N 34 14 43.9 E 132 14 03.9 E 132 13 58.7 13.6 400 1600 B Yakusyou-bana N 34 15 59.0 N 34 15 48.1 E 132 15 10.1 E 132 14 56.6 8.1 400 1600 C Narukawa Oki 1 N 34 15 38.1 N 34 15 35.6 E 132 14 44.7 E 132 14 39.2 12.3 200 800 D Narukawa Oki 2 N 34 15 12.1 N 34 15 15.3 E 132 14 54.8 E 132 15 1.5 16.5 200 800 E Nagaura 1 N 34 14 58.5 N 34 14 47.3 E 132 15 53.2 E 132 16 3.9 3.9 400 1600 F Nagaura 2 N 34 14 56.6 N 34 14 48.5 E 132 15 48.4 E 132 15 57.7 13.3 400 1600 G Nagaura 3 N 34 14 36.1 N 34 14 48.6 E 132 15 47.9 E 132 15 38.9 17 400 1600 H Suyaura N 34 15 27.9 N 34 15 31.6 E 132 16 7.0 E 132 16 11.2 5 200 800 I Ajina Oki 1 N 34 18 55.1 N 34 18 59.9 E 132 18 44.1 E 132 18 51.9 9.2 300 1200 J Ajina Oki 2 N 34 18 47.1 N 34 18 51.9 E 132 18 51.1 E 132 18 56.0 8.4 200 800 K Daikoku 1 N 34 17 52.1 N 34 17 50.0 E 132 18 39.9 E 132 18 33.9 2.6 200 800 L Daikoku 2 N 34 17 47.4 N 34 17 50.0 E 132 18 13.2 E 132 18 18.8 9.9 200 800
33 Fig. 1. Stations of trawl-net survey in inner area of Hiroshima Bay. Fig. 2. Sampling by a trawl net (a, b), Ulva and other seaweeds sampled by a trawl net (c) and quadrat sampling by SCUBA at St.E (d).
34 Table 2 13 20 37 Ulva armoricana 2002 Table 2. List of seaweed and seagrass species sampled by the trawl-net and SCUBA survey. Trawling SCUBA Trawling SCUBA Chlorophyta Rhodophyta Ulva spp. spp. Gelidium elegans Chaetomorpha sp. sp. Chondracanthus tenellus Caulerpa okamurae Chondrus ocellatus Codium fragile Grateloupia filicina G. lanceolata Phaeophyta Hypnea charoides Kalymenia sp. sp. Dilophus okamurae Ahnfeltiopsis flabelliformis Dictyopteris latiuscula Stenogramma interrupta Hydroclathrus clathratus Schizymenia dubyi Petalonia fascia Gracilaria chorda Scytosiphon gracilis G. incurvata Undaria pinnatifida G. textorii Ecklonia kurome Lomentaria catenata Sargassum fusiforme Ceramium sp. sp. S. hemiphyllum Pterothamnion yezoense S. horneri Dasya sp. sp. S. macrocarpum Acrosorium venulosum S. muticum Hypoglossum barbatum S. piluliferum Martensia fragilis Seagrass Zostera marina 1 St. E 53.9 kg1 St. K 42.5 kg St. B St. H 20 kg 1 2 St. C, D 1 St. I 1kg Fig. 3 64 100 St. B St. E St. H St. K 98.5, 74.2, 69.5, 97.9 St. E 17.9 St. H 16.6 St. B, St. E, St. H, St. K 13.5, 25.0, 18.5, 52.0 g w.w. / m 2 Fig. 3 12 5 m St. E, St. H, St. K 5 10 m St. B, St. I, St. J, St. L 10 m St. A, St. C, St. D, St. F, St. G
35 5 m 5 10 m 10 m 31.8 5.3 0.81 g / m 2 Fig. 4 St. B, St. E, St. K 2 m 3751.2 122.4 1097.7 195.3 514.0 72.6 g / m 2 96.3 99.2 100 Fig. 3. Total amount of sampled seaweed (a) and estimated biomass per unit area (b) at each trawling station. : Ulva spp.; : Caulerpa okamurae; : Gracilaria incurvata; : others. Fig. 4. Mean biomass per unit area estimated by trawlnet surveys in three depth zones ( 5 m, 5-10 m, 10m ). 1998 2001 St. H 1 St. E 2001 8.1 m St. B 5 m 5 m St. I St. J Uchimura et al. 2004 4 m
36 10 m 2010 5 m Uchimura et al. 2004 5 m 30 g / m 2 2.0 m Fig. 2d20 30 5 m 5 m 2002 21 98-101 Hiraoka, M., Yoshida, G., 2010. Temporal variation in isomorphic phase and sex ratios of a natural population of Ulva pertusa (Chlorophyta). J. Phycol. 46. DOI: 10.1111/j.1529-8817.2010.00873.x Leliaert, F., Zhang, X., Ye, N., Malta, E, Engelen, A. H., Mineur, F., Verbruggen, H., De Clerck, O., 2009. Identity of the Quindao algal bloom. Phycol. Res. 57: 147-151. 1999 1-15 1998 31 13-18 2001 3 73-81 Uchimura, M., Yoshida, G., Hiraoka, M., Komatsu, T., Arai, S., Terawaki, T., 2004. Ecological studies of green
37 tide, Ulva spp. (Chlorophyta) in Hiroshima Bay, the Seto Inland Sea. Jap. J. Phycol. 52 (Supplement):17-22. 2001 Caulerpa okamurae Weber-van-Bosse in Okamura 3 63-71 Uno, S., Sakai, Y., Yoshikawa, K., 1983. Distribution of Ulva pertusa and amount of nitrogen in Yamaguchi Bay. Jap.J.Phycol. 31:148-155. 2010 47 19-29
38 Accumulation of Ulva spp. (Chlorophyta) and other seaweed thalli on the shallow sea bottom of Hiroshima Bay (A preliminary survey) GoroYOSHIDA 1,5), Masayuki UCHIMURA 2), Masanori HIRAOKA 3), Toshinobu TERAWAKI 1), Shogo ARAI 4) and Kazuo ISEKI 5) 1) National Research Institute of Fisheries and Environment of Inland Sea, Fisheries Agency, 2-17-5 Maruishi, Hatsukaichi, Hiroshima 739-0452, Japan 2) JICA Niger,523 rue des lacs,pl521,quartier Plateau,Commune 1,Niamey, Niger 3) Usa Marine Biological Institute, Kochi University, 194 Inoshiri, Usa, Tosa, Kochi 781-1164, Japan 4) Marine Algae Research Co.,Ltd, 3-9-4 Minatozaka, Shingu, Kasuya, Fukuoka 811-0114, Japan 5) Graduate School of Biosphere Science, Hiroshima University, 1-4-4 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8528, Japan Abstract Biomass of Ulva spp. (Chlorophyta) causing green tide and other seaweeds accumulated on shallow sea bottom in inner area of Hiroshima Bay was estimated by trawl-net and SCUBA surveys. Thirty-eight species of seaweed and seagrass was sampled, but Ulva spp. was dominant occupying 64-100 % in biomass of all samples. Ulva spp. was sampled most abundantly at the stations shallower than 5 m, and it was indicated that sea bottom with a gentle slope, and located offshore of sandy beaches or tidal-flats offers a suitable condition for Ulva growth. Key words: biomass, green tide, Hiroshima Bay, trawl net, Ulva spp.