Marine Algae in Matsushima Bay, Northeastern Honshu, Japan

Aquaculture Sci. 56（3），387－399（2008）

1 1 1 Michiko NARITA , Yukio AGATSUMA and Kazuya TANIGUCHI

Abstract: Marine algae were collected from March 2004 to February 2005 at Sabusawa Island, Hanabuchihama, and Funairi Island in Matsushima Bay (38°18Ń, 141°5É). A total of 134 species were collected, of which 54 species newly listed as marine plants in Matsushima Bay. The I/H value, the ratio of the number of species with isomorphic alternation of generations or no alternation (generally found in warm current areas; I ) to that of species with heteromorphic alternation of generations (generally found in cold current areas; H) in Matsushima Bay was 1.7, clearly higher than the values of 1.3－1.4 found in localities to the southern coast of the Oshika Peninsula (38°24Ń, 140°22É). This shows that Matsushima Bay belongs to the temperate floral region phytogeographically. The I/H value were higher than those found in the past. Cole’s coefficient index of similarity between past and present marine algal flora in Matsushima Bay showed no significant similarity. The marine algal flora in Matsushima Bay has changed to a warm current type in synchrony with the 1.5℃ increase in the average sea surface temperature from 1926－1935 to 1995－2004.

Key words: Flora; Floristic plant geography; Global warming; Water temperature

Kinkasan Island, off Oshika Peninsula, north- of the Oshika Peninsula and Matsushima Bay eastern Honshu, Japan (38°24´N, 141°34´E), (Takamatsu 1936). It is necessary to clarify the has been regarded as the geographical bound- present marine algal flora in Matsushima Bay, ary of marine algal flora between subarctic as the hydrographic condition off the Pacific and temperate regions (Okamura 1931). coast of northern Honshu may be different Recently, Endo et al. (2005) investigated the from that 70 years ago. In addition, the season- marine algal flora on the southern coast of the ality of marine algal flora, including the matura- Oshika Peninsula and compared it with the tion season of each species, has not still been florae reported in various localities along the studied in Matsushima Bay. The maturation Pacific coast of northeastern Honshu by using seasons provide useful knowledge for practical the I/H value (Nakahara and Masuda 1971), technologies of marine afforestation and aqua- a reference index affected by warm and cold culture. currents. They confirmed that the geographi- In the present study, we investigated the cal boundary of marine algal flora between the appearance and maturation seasons of marine subarctic and temperate regions was in the algae at three sites in Matsushima Bay, and locality from the southern coast of the Oshika compared them with those at other localities Peninsula to Matsushima Bay, because of along the Pacific coast of northern Honshu and similar I/H values between the florae along the past Matsushima Bay reported by Takamatsu northern (Agatsuma et al. 2000) and southern (1936). We found that marine algal flora in coasts of the Oshika Peninsula, and different Matsushima Bay is temperate, and sift to a values between those along the southern coast warm current type.

Received April 8, 2008: Accepted June 25, 2008. 1 Laboratory of Marine Plant Ecology, Graduate School of Agricultural Science, Tohoku University, Sendai, Miyagi 981-8555, Japan. 388 M. Narita, Y. Agatsuma and K. Taniguchi

generally found in warm current areas (I), to that Materials and methods of species with heteromorphic alternation of generations, generally found in cold current areas (H) Marine algae were collected monthly at (Nakahara and Masuda 1971). The C/P and I/H Sabusawa Island, Funairi Island, and Hanabuchi- values of the algae were calculated for comparison hama, Matsushima Bay (38°19Ń, 141°6É), with those previously collected in Matsushima from March 2004 to February 2005 (except in Bay (Takamatsu 1936) and in eight other localities March, April, June, and November at Funairi along the Pacific coast of northeastern Honshu, Island) (Fig. 1). Algae were fixed with 10% for- Japan: Shimokita Peninsula (41°20Ń, 140°49É) malin sea water, identified, then preserved as (Fuji and Yamamoto 1972), Miyako (39°37Ń, herbarium specimens. Presences of reproduc- 142°0É) (Taniguchi et al. 1979), Okirai Bay and tive cells in the thalli of the algae collected at its vicinity (39°6Ń, 141°50É) (Takamatsu 1974), Sabusawa Island and Hanabuchihama were Kitakami (38°36Ń, 141°30É) (Nakata et al. observed. We classified the marine algae into 5 2001), Ogatsu (38°30Ń, 141°31É) (Taniguchi life-form groups: crustaceous algae, small annu- et al. 1985), Tomarihama (38°21Ń, 141°31É) als, small perennials, large annuals, and large (Agatsuma et al. 2000), Sasunohama (38°24Ń, perennials, according to Taniguchi (1996). 140°22É) (Endo et al. 2005), and Iwaki (36°56Ń, C/P is the ratio of the number of Chlorophyta 140°55É) (Suda 1987; Sato et al. 2001) (Fig. 1). species, generally found in warm current areas The differences in marine algal flora among (C), to that of Phaeophyta species, generally found present Matsushima Bay and that 70 years ago in cold current areas (P) (Segawa 1956). I/H is (Takamatsu 1936), that along the northern the ratio of the number of species with isomor- coast of the Oshika Peninsula (Agatsuma et al. phic alternation of generations or no alternation, 2000), and that along the southern coast (Endo

140° 142° 144°E 41° Kitakami Shimokita Peninsula North- eastern Honshu Miyako 39° Okirai Bay Ogatsu Kitakami River

Pacific Ocean Miyagi Prefecture Enoshima Is. O 37°N Iwaki sh Sasunohama ik a Matsushima Bay P e n Sabusawa Is. in Tomari- su hama la Funairi Is. Hanabuchihama 020km

Fig. 1. Three study sites in Matsushima Bay where marine algae were collected (solid circles). Nine localities along the Pacific coast of northeastern Honshu where marine algal florae were reported in previous papers (Takamatsu 1936, 1974, Fuji and Yamamoto 1972, Taniguchi et al. 1979, 1985, Suda 1987, Agatsuma et al. 2000, Sato et al. 2000, Nakata et al. 2001, Endo et al. 2005) (open circles). Marine Algae in Matsushima Bay 389 et al. 2005) were analyzed by Cole’s coefficient seasonal temperature at Enoshima Island in index (Cole 1949), and statistical significance 2004 was similar to that of the 30-year average. was tested by chi-square test. The temperatures in Matsushima Bay and at In marine algae in Matsushima Bay 70 years Sasunohama were higher than that at Enoshima ago, four fucoid species, Sargassum fulvellum, S. Island from April through October and lower hemiphyllum, S. patens and S. piluliferum geo- from December through February. The annual graphically distribute in the southern regions range in temperature in Matsushima Bay was from Cape Inubou (35°42Ń, 140°52É), and wider than that at Sasunohama. no recorded on the coast of Iwaki, Fukushima Figure 3 shows the appearance and maturation Prefecture (Suda 1987; Sato et al. 2001) (Fig. 1). season of marine algae collected at Sabusawa In addition, these algae are found only as drifts Island, Hanabuchihama and Funairi Island. We even at the present time (K. Taniguchi personal collected 136 marine species: 20 belonging to com.). Hence, these four species were omitted. the Chlorophyta, 32 to the Phaeophyta, 82 to the We used the bimonthly sea surface water tem- Rhodophyta, and 2 seagrasses. perature in Matsushima Bay and the monthly At Sabusawa Island, we collected 2 crusta- temperature at Sasunohama, on the southern ceous algae, 62 small annuals, 31 small peren- coast of Oshika Peninsula, and the long-term sea nials, 5 large annuals, and 8 large perennials. surface water temperature at Enoshima Island Seasonal changes in numbers of mature species (38°23Ń, 141°35É) measured every 10 days by life-form are shown in Fig. 4. The number by Miyagi Prefecture Fisheries Research and of matured large annuals and large perenni- Development Center. als were so small that they were summed. Eight to 15 species of small annuals and 5 to Results 15 species of small perennials matured all year round. In particular, the number of mature small Figure 2 shows the seasonal change of sea perennials increased in autumn (September－ surface water temperatures in Matsushima Bay November). Among the large algae of the marine from January to December 2004, and the aver- forest, Undaria pinnatifida matured from May ages at Enoshima Island for 1974－2003. The to July, Laminaria japonica and Eisenia bicyclis from October to December, and seven fucoid species from May to August. 30

Discussion )

℃ Takamatsu (1936) reported 122 species of 20 marine algae in Matsushima Bay: 14 Chlorophyta, 38 Phaeophyta, and 70 Rhodophyta. We newly recorded 54 species of marine algae and two species of seagrasses and eliminated 38 species from 10 the original list. To clarify the phytogeographical character- Sea surface temperature ( istics of marine algal flora in Matsushima Bay and differences between the present and past 0 studies (Takamatsu 1936), we show the C/P JMAMJJASONDF and I/H values in Fig. 5 and Cole’s coefficient Fig. 2. Seasonal change in sea surface water tempera- index in Table 1 of the marine algal florae in tures from January to December 2004 in Matsushima Bay nine localities along the Pacific coast of north- (solid circles), Sasunohama (open circles), and Enoshima Island (solid squares) and 30-year average temperature eastern Honshu from Shimokita Peninsula (1974－2003) at Enoshima Island (open squares). to Iwaki. No relation was found between C/P 390 M. Narita, Y. Agatsuma and K. Taniguchi

Fig. 3. The occurrence and maturation periods of marine algae collected from March 2004 to February 2005 at Sabusawa Island, Hanabuchihama and Funairi Island. M, thallus-forming reproductive cells; ○, unilocular sporangia; ◎, plurilocular sporangia; , tetrasporangia; ♂, male reproductive organ; ♀, female reproductive organ; *, species newly listed in Matsushima Bay. 2004 2005 Species Collection site MAMJ J A SOND J F Crustaceous algae 1 Codium hubbsii * Sabusawa Is. Funairi Is. 2 Pneophyllum zostericola * Sabusawa Is. ＋○ ＋○ ＋○ ＋○ ＋○♀ ＋○ Hanabuchihama ＋○ ＋○ ＋○ ＋○ ＋○ ＋○ Funairi Is. 3 Titanoderma tumidlum * Hanabuchihama Funairi Is. Small annual algae 4 Monostroma angicava Sabusawa Is. MM M Hanabuchihama MM M Funairi Is. 5 Protomonostroma undulatum * Sabusawa Is. M Hanabuchihama M Funairi Is. 6 Enteromorpha intestinaris Sabusawa Is. M Hanabuchihama Funairi Is. 7 Enteromorpha linza * Sabusawa Is. MMMM M Hanabuchihama M Funairi Is. 8 Ulva pertusa Sabusawa Is. MMMM M Hanabuchihama Funairi Is. 9 Chaetomorpha crassa Hanabuchihama Funairi Is. 10 Chaetomorpha moniligera Hanabuchihama Funairi Is. 11 Chaetomorpha spiralis Sabusawa Is. Hanabuchihama Funairi Is. 12 Cladophora albida * Hanabuchihama 13 Cladophora fascicularis * Hanabuchihama 14 Cladophora opaca * Sabusawa Is. Hanabuchihama M Funairi Is. 15 Cladophora rudolphiana * Funairi Is. 16Cladophora sakaii * Sabusawa Is. M Funairi Is. 17 Cladophora stimpsonii * Sabusawa Is. Funairi Is. 18 Codium cylindricum * Sabusawa Is. Funairi Is.

Marine Algae in Matsushima Bay 391

Fig. 3. continued

2004 2005 Species Collection site MAM J J A S OND J F 19 Codium fragile Sabusawa Is. Hanabuchihama Funairi Is. 20 Bryopsis hypnoides * Sabusawa Is. Hanabuchihama Funairi Is. 21 Bryopsis maxima * Sabusawa Is. Hanabuchihama Funairi Is. 22 Bryopsis plumosa Hanabuchihama Funairi Is. 23 Sphacelaria rigidula * Sabusawa Is. ○ 24 Papenfussiella kuromo Hanabuchihama ○○ Funairi Is. 25 Elachista okamurae * Hanabuchihama 26 Halothrix ambigua * Sabusawa Is. ◎ 27 Leathesia difformis* Sabusawa Is. Hanabuchihama ○◎ 28 Punctaria latifolia * Sabusawa Is. ○◎○◎ ○◎○◎ ○◎○◎ Hanabuchihama ◎ ○◎ ◎ Funairi Is. 29 Colpomenia bullosa Sabusawa Is. ◎ ◎ Hanabuchihama ◎◎ Funairi Is. 30 Colpomenia sinuosa Sabusawa Is. ◎ ◎ ◎ ◎ ◎ Hanabuchihama 31 Petalonia fascia Sabusawa Is. ◎ ◎ Hanabuchihama ◎◎◎ 32 Scytosiphon lomentaria Sabusawa Is. ◎ ◎ ◎ ◎ ◎ ◎ Hanabuchihama ◎◎◎◎ ◎ Funairi Is. 33 Bangia atropurpurea * Hanabuchihama MM 34 Bangia gloiopeltidicola * Sabusawa Is. MM M Hanabuchihama MM M Funairi Is. 35 Porphyra yezoensis Sabusawa Is. ♂♀ ♂♀ ♂♀ ♂♀ ♂♀ Hanabuchihama ♂♀ ♂♀ ♂♀ ♂♀ Funairi Is. 36 Nemalion vermiculare * Funairi Is. 37 Hyalosiphonia caespitosa * Sabusawa Is. ＋○ 38 Neodilsea yendoana Sabusawa Is. ＋○ ＋○ Hanabuchihama ＋○ ♀ Funairi Is. 392 M. Narita, Y. Agatsuma and K. Taniguchi

Fig. 3. continued

2004 2005 Species Collection site MAM J J A S OND J F 39 Pikea yoshizakii Sabusawa Is. Funairi Is. 40 Gloiosiphonia capillaris Sabusawa Is. ♀ 41 Grateloupia filicina Sabusawa Is. ＋○ ＋○ ＋○ ＋○ Funairi Is. 42 Grateloupia livida Sabusawa Is. ＋○♀ ＋○ ＋○♀ ＋○♀ ＋○ ＋○♀ Hanabuchihama ＋○ ＋○♀ ＋○♀ Funairi Is. 43 Grateloupia okamurae * Funairi Is. 44 Grateloupia turuturu * Sabusawa Is. ♀ ＋○♀ ＋○♀ ＋○ ＋○♀ Hanabuchihama ＋○♀ ♀♀♀♀＋○♀ ＋○♀ Funairi Is. 45 Prionitis ramosissima * Sabusawa Is. ＋○ 46 Hypnea charoides * Sabusawa Is. ＋○ 47 Callophyllis adnata Hanabuchihama ＋○ 48 Callophyllis crispata Sabusawa Is. ＋○ ＋○♀ ＋○ Hanabuchihama ＋○ Funairi Is. 49 Tsengia lancifolia Sabusawa Is. Hanabuchihama ♀♀ Funairi Is. 50 Plocamium recurvatum Sabusawa Is. Funairi Is. 51 Plocamium telfairiae Sabusawa Is. ＋○ ＋○ ＋○ Hanabuchihama ＋○ ＋○ ＋○ ＋○ ＋○ Funairi Is. 52 Schizymenia dubyi Sabusawa Is. ♀ ♀♀♀ ♀♀♀ Hanabuchihama ♀♀ Funairi Is.

53 Gracilaria vermiculophylla Sabusawa Is. ♂ ＋○♀＋○♀♂ ＋○♀ ＋○♀♂ ＋○♀♂ ＋○♀♂ ♀♂ ♀ Hanabuchihama ♂ ＋○♂＋○♀♂ ＋○♀ ＋○♀ ＋○♀♂ ♀♂ ♀♀ Funairi Is. 54 Champia parvula * Funairi Is. 55 Chrysmenia wrightii Sabusawa Is. ＋○ ♀ Funairi Is. 56 Rhodymenia pertusa * Funairi Is. 57 Aglaothamnion callophyllidicola * Sabusawa Is. ＋○ Funairi Is. 58 Antithamnion sp. * Sabusawa Is. ＋○ Hanabuchihama ＋○ 59 Antithamnionella spirographidis * Sabusawa Is. 60 Campylaephora hypnaeoides Sabusawa Is. ＋○ Hanabuchihama ＋○ Marine Algae in Matsushima Bay 393

Fig. 3. continued

2004 2005 Species Collection site MAM J J A S OND J F 61 Ceramium boydenii Sabusawa Is. ＋○ ＋○ Hanabuchihama ＋○ Funairi Is. 62 Ceramium japonicum Sabusawa Is. ＋○ ＋○ ＋○ 63 Ceramium kondoi Sabusawa Is. ♀ ＋○♀＋○♀ ＋○♀ Hanabuchihama ♀ ＋○♀ ♀ Funairi Is. 64 Ceramium paniculatum Sabusawa Is. ＋○♀ ＋○♀ 65 Griffithsia japonica* Sabusawa Is. ♂ ＋○ ♀♀♀ Hanabuchihama ＋○ ＋○ ＋○ ＋○♀ ＋○ ♀♂ ＋○♂ Funairi Is. 66 Psilothallia dentata Hanabuchihama ♀ 67 Reinboldiella schimitziana Sabusawa Is. ＋○♀ Hanabuchihama Funairi Is. 68 Heterosiphonia pulchra Sabusawa Is. ＋○ Hanabuchihama Funairi Is. 69 Acrosorium polyneurum * Sabusawa Is. ＋○ ＋○ ＋○ ＋○ ＋○ Hanabuchihama ＋○ ＋○ ＋○ ＋○ Funairi Is. 70 Acrosorium venulosum Sabusawa Is. ＋○ ＋○ Funairi Is. 71 Acrosorium yendoi Sabusawa Is. 72 Delesseria serrulata Funairi Is. 73 Marionella schmitziana * Sabusawa Is. 74 Phycodrys radicosa * Sabusawa Is. ＋○ Hanabuchihama ＋○ Funairi Is. 75 Sorella repens * Sabusawa Is. ＋○ 76 Chondria crassicaulis Sabusawa Is. ＋○ ＋○ Hanabuchihama ＋○ ＋○ ＋○ Funairi Is. 77 Chondria dasyphylla * Sabusawa Is. ＋○ Funairi Is. 78 Chondria tenuissima Sabusawa Is. 79 Polysiphonia abscissa * Funairi Is. 80 Polysiphonia japonica * Sabusawa Is. ♀♂＋○♀＋○♀♂ ＋○♀♂ ＋○ Funairi Is. 81 Polysiphonia senticulosa * Sabusawa Is. ＋○♀♂ ＋○♀ ＋○ Funairi Is. 82 Polysiphonia yendoi * Sabusawa Is. ＋○ ＋○ ♀ 83 Symphyocladia linearis * Sabusawa Is. ＋○♀ ＋○ Funairi Is. 394 M. Narita, Y. Agatsuma and K. Taniguchi

Fig. 3. continued

2004 2005 Species Collection site MAM J J A S OND J F Small prennial algae 84 Analipus japonicus Sabusawa Is. ◎ ◎ ○ Hanabuchihama ○○○◎ ◎ ○◎ ○◎ Funairi Is. 85 Dictyopteris divaricata Sabusawa Is. Funairi Is. 86 Dictyota dichotoma * Sabusawa Is. ＋○ Hanabuchihama Funairi Is. 87 Pachydictyon coriaceum Hanabuchihama ＋○ ＋○ ＋○ ＋○ ＋○ 88 Spatoglossum pacificum Sabusawa Is. ♀ ＋○ ＋○ ＋○ Funairi Is. 89 Ishige okamurae Funairi Is. 90 Ishige sinicola * Sabusawa Is. Funairi Is. 91 Myelophycus simplex Funairi Is. 92 Amphiroa dilatata * Sabusawa Is. 93 Corallina officinaris Sabusawa Is. ＋○ ＋○ ＋○ ♀ Funairi Is. 94 Corallina pilulifera Sabusawa Is. ＋○ ＋○ ＋○ ＋○ ＋○ ＋○ ＋○ ＋○ Hanabuchihama Funairi Is. 95 Marginisporum aberrans * Funairi Is. 96 Gelidium divaricatum Sabusawa Is. ＋○ ＋○ ＋○ ＋○ ＋○ ＋○ ＋○ ＋○ Hanabuchihama ＋○ ＋○ ＋○ ＋○ ＋○ Funairi Is. 97 Gelidium pusillum Sabusawa Is. ＋○ Hanabuchihama ＋○ ＋○ 98 Gelidium subfastigiatum Sabusawa Is. ＋○ Funairi Is. 99 Gelidium vagum Sabusawa Is. ♀ 100 Pterocladiella capillacea Sabusawa Is. ＋○ Funairi Is. 101 Caulacanthus ustulatus Sabusawa Is. ＋○ ＋○ ＋○ Hanabuchihama ＋○ ＋○ ＋○ Funairi Is. 102 Gloiopeltis complanata Funairi Is. 103 Gloiopeltis furcata Sabusawa Is. ＋○♀＋○♀ ＋○♀ Hanabuchihama ＋○ ＋○ Funairi Is. 104 Chondracanthus intermedius Sabusawa Is. ♀ Hanabuchihama ♀♀♀ Funairi Is. Marine Algae in Matsushima Bay 395

Fig. 3. continued

2004 2005 Species Collection site MAM J J A S OND J F 105 Chondrus giganteus Sabusawa Is. ＋○ ＋○ ＋○ ＋○ ＋○ ＋○♀＋○♀ ＋○♀ ＋○♀ Hanabuchihama ＋○ ＋○ ＋○ ＋○ ＋○♀ ＋○ ＋○♀ ＋○♀ ＋○ ＋○♀ ＋○♀ ＋○♀ Funairi Is. 106 Chondrus ocellatus Sabusawa Is. ＋○♀ ♀ ＋○♀＋○♀ ＋○ ＋○♀ Hanabuchihama ＋○ ＋○♀ ＋○♀ ♀♀ Funairi Is. 107 Mazzaella japonica * Sabusawa Is. ＋○♀＋○♀ ＋○♀ ♀ ＋○♀ ＋○♀ Hanabuchihama ＋○ ＋○♀ ＋○♀ ♀ Funairi Is. 108 Carpopeltis affinis Sabusawa Is. ♀ ＋○♀＋○♀ ＋○ ＋○ Hanabuchihama ＋○ ＋○♀ ＋○ ♀ ＋○ Funairi Is. 109 Carpopeltis prolifera Sabusawa Is. ＋○ ＋○ ＋○ Hanabuchihama ＋○ ♀ Funairi Is. 110 Grateloupia elliptica Sabusawa Is. ♀ ＋○♀ ＋○ ＋○♀＋○♀ ＋○♀ ＋○ ＋○♀ Hanabuchihama ＋○ ♀ ＋○ ＋○ ＋○♀＋○♀ Funairi Is. 111 Ahnfeltiopsis flabelliformis Sabusawa Is. ♀♀♀♀ Hanabuchihama ♀♀ Funairi Is. 112 Ahnfeltiopsis paradoxa Sabusawa Is. ♀♀♀♀ ♀♀♀♀♀♀ Hanabuchihama ♀♀♀♀ ♀ ♀♀♀♀♀ Funairi Is. 113 Lomentaria hakodatensis Sabusawa Is. Hanabuchihama ＋○ ＋○ ＋○♀ ＋○ Funairi Is. 114 Laurencia intermedia * Sabusawa Is. ＋○♀ ♀♂＋○ 115 Laurencia nipponica Sabusawa Is. ＋○♀＋○♀ ＋○ Hanabuchihama ＋○ ＋○ ＋○ Funairi Is. 116 Laurencia pinnata * Hanabuchihama Funairi Is. 117 Laurencia saitoi * Funairi Is. 118 Laurencia venusta * Sabusawa Is. ＋○♀ ＋○ ♀ Hanabuchihama ＋○♀ Funairi Is. 119 Neorhodomela munita Sabusawa Is. ＋○♀ ♀ ＋○ ＋○♂ 120 Symphyocladia latiuscula Sabusawa Is. ＋○ ＋○ ＋○ ＋○ Hanabuchihama ＋○ ＋○ ＋○ Funairi Is. Large annual algae 121 Desmarestia ligulata Sabusawa Is. Hanabuchihama 396 M. Narita, Y. Agatsuma and K. Taniguchi

Fig. 3. continued

2004 2005 Species Collection site MAM J J A S OND J F Funairi Is. 122 Desmarestia viridis Sabusawa Is. Funairi Is. 123 Undaria pinnatifida Sabusawa Is. ○ ○ ○ Hanabuchihama ○○ Funairi Is. 124 Chorda filum Hanabuchihama 125 Laminaria japonica * Sabusawa Is. ○ ○ ○ Hanabuchihama Funairi Is. 126 Sargassum horneri Sabusawa Is. ♀♂ ♀ Hanabuchihama ♀ ♀♂ Funairi Is. Large perennial algae 127 Eisenia bicyclis Sabusawa Is. ○ ○ ○ Hanabuchihama ○○○○○ Funairi Is. 128 Myagropsis myagroides Sabusawa Is. ♂ 129 Sargassum fusiforme Sabusawa Is. ♂♀ Funairi Is. 130 Sargassum confusum * Sabusawa Is. ♀ 131 Sargassum muticum Sabusawa Is. ♀♂ ♀♂ ♀♂ Hanabuchihama ♀♂ ♀♂ ♀♂ Funairi Is. 132 Sargassum ringgoldianum Sabusawa Is. ♀♀ Funairi Is. 133 Sargassum siliquastrum Sabusawa Is. Funairi Is. 134 Sargassum thunbergii Sabusawa Is. ♂♀ Hanabuchihama ♀♂ Funairi Is. 134 Sargassum thunbergii Sabusawa Is. ♂♀ Hanabuchihama Funairi Is. 134 Sargassum thunbergii Sabusawa Is. ♂♀ Hanabuchihama ♀♂ Funairi Is. Seagrass 135 Phyllospadix iwatensis * Sabusawa Is. Hanabuchihama Funairi Is. 136 Zostera marina * Sabusawa Is. Funairi Is. Marine Algae in Matsushima Bay 397 and latitude, but I/H clearly increased with of fresh water inflow from the Kitakami River. lowering latitude except for the high value in Nakahara and Masuda (1971) suggested that Ogatsu, where many Chlorophyta, such as differences of C/P values in narrow area was Enteromorpha species with isomorphic alterna- not clear compared with that of I/H value. tion of generations, grow under the influence The I/H values in the northern localities from Sasunohama range between 1.3 and 1.4, clearly 15 lower than the new value of 1.7 in Matsushima Bay. According to Nakahara and Masuda (1971), I/H value is 1.4 and under in subarctic region, 10 while ranges between 1.5 and 4.0 in temperate region. Therefore, this result shows that the phytogeographical boundary of marine algal flora 5

Number of species between subarctic and temperate regions lies between Sasunohama and Matsushima Bay, as 0 reported by Endo et al. (2005). MAMJ J A S OND J F The C/P and I/H values in Matsushima Bay 2004 2005 were 0.4 and 1.5, respectively, 70 years ago and Fig. 4. Seasonal changes in number of mature marine 0.6 and 1.7 in the present study (Fig. 5). These algal species by each life-form group collected at new higher values suggest that the marine algal Sabusawa Island. Solid circles, small annual algae; open flora has changed markedly to a warm current circles, small perennial algae; solid squares, large annual and perennial algae. type. Cole’s coefficient indices of similarity

Shimokita Peninsula (1972)

Miyako (1979)

Okirai Bay (1974)

Kitakami (2001)

Ogatsu (1985)

Tomarihama (2000)

Sasunohama (2005)

Matsushima Bay (1936) Matsushima Bay (this study)

Iwaki (1987)

Iwaki (2001)

0 0.4 0.8 1.2 1.6 2.0 C/P, I/H

Fig. 5. C/P (open) and I/H values (dark) in nine localities along the Pacific coast of northeastern Honshu from Shimokita Peninsula to Iwaki. 398 M. Narita, Y. Agatsuma and K. Taniguchi

Table 1. Cole’s coefficient indices among marine algal florae at Tomarihama (Agatsuma et al. 2000), Sasunohama (Endo et al. 2005), Matsushima Bay surveyed from March 2004 to February 2005 (this study) and Matsushima Bay 70 years ago (Takamatsu 1936) Tomarihama Sasunohama Matsushima Bay (this study) Sasunohama 0.322＊ Matsushima Bay (this study) 0.086 0.213＊ Matsushima Bay (1936) 0.030 0.055 0.096 ＊p＜0.05. between the adjacent localities Tomarihama and Sasunohama, and Sasunohama and Matsushima

Bay (this study), are high, and the similarity is ) 20 significant (p＜0.05) (Table 1). By contrast, the ℃ coefficient indices of distant localities are low, and there is no significant similarity between Matsushima Bay 70 years ago and Tomarihama, Sasunohama, or Matsushima Bay now. This sub- 10 stantiates the change to the marine algal flora in present Matsushima Bay to a warm current type. Sea surface temperature ( Inshore areas off the Pacific coast of northeastern Honshu are mixed by the Oyashio and Kuroshio currents. An increase in the first 0 JMAMJJASONDF Oyashio branch extending the southern limit to Fig. 6. Seasonal changes in average sea surface water ° 37 N from spring to summer results in marked temperature every 10 days at Enoshima Island from 1926 low water temperature off the Pacific coast in to 1935 (broken line) and from 1995 to 2004 (solid line). Tohoku (Okuda 1986; Murakami 1994). Kodama et al. (1995) divided long-term water tempera- reproductive cells and promote the growth of ture since 1911 into five periods: mixed water edible algae and those consisting marine forest period, 1911－1923, with low water temperature areas. From the knowledge of maturation peri- accounting for 46%, cold water period, 1924－ ods of each marine alga in this study, denuded 1947, with persistence of low water temperature, ones should be introduced from August to warm water period, 1948－1973, with relatively September for an establishment of kelp forests, high water temperature, cold water period, 1974 from March to April for fucoids forests, and －1987, and warm water period after 1988. from January to April for intertidal edible algae, Fig. 6 shows seasonal changes in average sea such as the brown alga Analipus japonicus and surface temperatures at Enoshima Island during the red alga Gloiopeltis furcata. the 10 years, 1926－1935, before the report of Takamatsu (1936) and, 1995－2004, before this Acknowledgements study. The present annual average water temperature is 13.9℃, 1.5℃ higher than 70 years We sincerely thank Dr. R. Sasaki of the Miyagi ago. In particular, the present temperature in Prefecture Fisheries Research and Development late December is 12.4℃, 3.0℃ higher than in Center for providing data on sea water tempera- the past. From these results, we conclude that ture and valuable literature, and Prof. M. Iwata the marine algal flora in Matsushima Bay has of Kitasato University for providing valuable changed to a warmer current type. This change literature. We are also grateful to the staff of the may be associated with global warming. Urato-Tobu and Sichigahamamachi Fisheries In Japan, denuded rocks, such as the arti- Cooperative Associations for their permission ficial reefs have been introduced in intertidal and cooperation to collect marine algae in their and shallow subtidal areas to collect algal fishery areas. Marine Algae in Matsushima Bay 399

6, 33-39 (in Japanese). References Okamura, K. (1931) Kaisan Shokubutsu no Chiriteki Bunpu. Iwanami shoten, Tokyo, 86 pp. (in Japanese). Okuda, K. (1986) Occurrence of extremely low tempera- Agatsuma, Y., M. Ogawa, K. Taniguchi and H. Yamada ture in the coastal region of the Tohoku area associ- (2000) Marine algal flora off the coast of Tomari- ated with interannual variations of the Oyashio. Bull. Hama along the Oshika Peninsula, Japan. Wildlife Tohoku Reg. Fish. Res. Lab., 48, 87-96 (in Japanese). Conservation Japan, 5, 47-53 (in Japanese). Sato, T., Y. Nakata, Y. Agatsuma and K. Taniguchi (2001) Cole, L. C. (1949) The measurement of interspecific asso- Marine algal flora off the coast of Shimo-Kajiro in ciation. Ecology, 4, 411-424. Iwaki City, Japan. Wildlife Conservation Japan, 6, Endo, H., Y. Agatsuma and K. Taniguchi (2005) Marine 41-46 (in Japanese). algae from Sasunohama, on the southern coast of Segawa, S. (1956) Colored illustrations of the seaweeds of Oshika Peninsula, Japan. Biosphere Conservation, 7, Japan. Hoikusha Publishing Co., Ltd., Osaka, 196 pp. 29-38. (in Japanese). Fuji, A. and H. Yamamoto (1972) Shimokita Hanto Seibu Suda, M. (1987) Marine algae from the coast of Iwaki City, Kaigan no Teisei Seibutsu. In “Shimokita Hanto Fukushima Prefecture. Japan. J. Phycol., 35, 22-33 (in Kokutei Koen (Kasho) Chosa Hokokusho” (ed. by Japanese). Aomoriken), pp.55-88 (in Japanese). Takamatsu, M. (1936) The marine algae from Matsushima Kodama, J., H. Nagashima and Y. Izumi (1995) Long-term bay, Miyagi Prefecture, northeastern Honshu, Japan. variation in the “Mangoku Herring”, Clupea pallasi Saito Ho-on kai Mus. Res. Bull., 8, 1-43. VALENCIENNES resources in relation to the ocean envi- Takamatsu, M. (1974) An atlas of marine algae from Okirai ronments in the waters off Sanriku and Joban. Bull. bay and its vicinities, Iwate Prefecture Kitasato Miyagi pref. Fish. Res. Dev. Cen., 14, 17-36 (in Daigaku Suisan Gakubu, Iwate, 42 pp. (in Japanese). Japanese). Taniguchi, K., H. Kito and K. Akiyama (1979) Marine algae Murakami, M. (1994) On long-term variations in hydro- from the Miyako coast of Iwate Prefecture. Bull. graphic conditions in the Tohoku area. Bulletin. Tohoku Reg. Fish. Res. Lab., 41, 141-148 (in Japanese). Tohoku Nat. Fish. Res. Ins., 56, 47-56 (in Japanese). Taniguchi, K., H. Hara, Y. Sato, Y. Osada and H. Suenaga Nakahara, H. and M. Masuda (1971) Type of life cycle and (1985) List of marine algae from the Ogatsu coast of geographical distribution of marine green and brown Miyagi Prefecture. Bull. Tohoku Reg. Fish. Res. Lab., algae in Japan. Mar. Sci. Monthly, 3, 24-26 (in 47, 11-20. Japanese). Taniguchi, K. (1996) Primary succession of marine algal Nakata, Y., Y. Agatsuma and K. Taniguchi (2001) Marine communities in the sublittoral zone off Oshika algal flora off the coast of Jusan-Hama at Kitakami in Peninsula, Japan. Nippon Suisan Gakkaishi, 62, Miyagi Prefecture, Japan. Wildlife Conservation Japan, 765-771 (in Japanese).

松島湾の海藻

成田美智子・吾妻行雄・谷口和也

2004年 3 月から2005年 2 月，東北地方松島湾内の寒風沢島，花渕浜，船入島で海藻を採集した。採集した海藻計134種のうち，54種を松島湾の海藻として新たに記載できた。寒暖流の影響度の指標である I/H値を東北地方太平洋沿岸で比較したところ，松島湾の I/H値は1.7であり，佐須浜以北の I/H値1.3～1.4と大きな相違を示したことから，松島湾は海藻地理学上温帯区系に属することが確認された。本研究と70年前の松島湾の海藻（Takamatsu 1936）における I/H値，Cole（1949）の類似度を比較した結果，現在の松島湾の I/H値は70年前より上昇し，現在と過去の松島湾の海藻相の類似度は低く有意な関連がなかった。松島湾の海藻相は年平均水温が70年前より1.5℃上昇したことに同調して暖流系化したと考えられる。