水研センター研報，第32号，115−118，平成22年
Bull. Fish. Res. Agen. No. 32, 115‑118, 2010

Seedling production inusing Suruga Bay deep-sea
water for restoration of kelp beds in isoyake area
Kazumi NIMURA＊1, Hiroyuki NODA

＊2

and Kazutoshi OKAMOTO＊3

Abstract;
is distributed from central to southern Pacific coast of Japan. The
wild sporophytes of the kelp extincted along the coasts of Omaezaki and Makinohara Cities
in Shizuoka Prefecture after deforestation called isoyake (cf. non-urchin barren here) in 1980 s.
Fortunately, we have cultured the native sporophytes collected from Omaezaki Cape in
our laboratory. Suruga Bay deep-sea water (DSW) is nutrient rich, cold and clean sea water
pumped from two depths of 397 and 687m with pipelines. As nitrate and phosphate concentrations of DSW (ex. NO3=21.1〜30.7μM, PO4=1.7〜2.8μM in 2007) are higher than that ofsurface sea water (ex. NO3=4.0〜14.4μM, PO4=0.3〜1.2μM in 2007), growth rate of juvenile
sporophyte was higher in DSW than surface seawater. Therefore, we used DSW as
culture medium for seedling production. Seedling production was started by the homogenization of the cultured gametophytes with the mixer. Culturing 1〜2 weeks later, numerous
number of the microscopic free living sporophytes were obtained. These sporophytes wassettled on the strings within a day in batch culture and then cultured for about one monthin DSW. This seedling of thewas transplanted to isoyake area for restoration ofthe kelp forests. The method of culture and transplantation on blocks were described here.
Key words: Deep-sea water,, Isoyake, Seedling, transplantation

Necessity of seedling production inThere remained a few small kelp forests after mid
1990 s, but in 2000 s, no wild

(Laminariales) is distributed

sporophytes

can be found on the coast. Therefore there is nofrom central to southern Pacific coast of Japan(Yoshida, 1998). The standard Japanese name ofis Sagarame , which was named after
Sagara Town

(now incorporated in Makinohara

City: Fig. 1) near the Omaezaki Cape in Shizuoka
Prefecture.

has been utilized as a food incentral and west areas in Shizuoka Prefecture; thiskelp contains much mucus polysaccharide. Before
mid 1980 s, there had been a vast kelp forest ofandalong the coast ofMakinohara and Omaezaki Cities (Hasegawa,2003). Then, the kelp forests have decreased andreplaced by barren ground (cf. non-urchin barrenhere). The phenomenon was a type ofIsoyake .

Fig. 1. Map indicates the location described in thetext.

2010年 月 日受理（Received on July 1. 2010）＊1
Shizuoka Prefectural Research Institute of Fishery, 3690 Kogawa, Shizuoka 425-0033, Japan＊2
Suruga-Bay deep seawater aquaculture research center of Shizuoka, Prefectural Research Institute of Fishery, 136-24 Iwashigashima, Yaizu,
Shizuoka 425-0032, Japan＊3
Office of Fishery management, Shizuoka Prefectural Office, 9-6 Otemachi, Aoi, Shizuoka, Shizuoka 420-8601, Japan

Kazumi NIMURA, Hiroyuki NODA and Kazutoshi OKAMOTO
hope of recruitments in natural condition. However,specific pathogens and artificial contaminants are

fortunately, we have cultured the native

included, 3) Coldness: water temperature of DSW issporophytes collected from Omaezaki cape in ourlow below 10℃ and stable.

laboratory. Our purposes were the production ofThe fluctuations of nitrate concentration in DSW

seedling in the laboratory and transplantation using

and SSW in 2007 were shown in Fig. 2. Nitrate

this seedling for the restoration of the kelp beds. In

concentration of DSW (21.1 〜 30.7μM) was higher

this paper, the method of preparation of seedlingthan that of SSW (4.0 〜 14.4 μM). Another nutrient,using deep seawater and transplantation on to thephosphate concentration of DSW was also higher

blocks are described.

concentration during the year (DSW: 1.7 〜 2.8 μM;
SSW: 0.3 〜 1.2 μM). We investigated the effects ofCharacteristics of Suruga Bay deep-sea water andjuvenile growth

DSW and SSW as culture mediaum on the growthof juvenile

sporophytes. Juvenile sporophyte

was larger in the length in dsw than in SSW at theSuruga Bay deep-sea water (DSW) was pumped

end of culture (Fig. 3). Therefore we produced thefrom Suruga Bay, Yaizu City, Shizuoka Prefecture,seedling offrom depths of 397 m and 687 m using pipelines

to Isoyake area.

using DSW and transplanted(Fig. 1). In this manuscript, the definition of DSW
is the seawater existed under 200m in depth in theSeedling production using Deep seawater

ocean (Nakashima 2002). The deep layer below 200m in depth is mostly under compensation depth;Life cycle ofconsists of macroscopic

degradation rate is higher than production rate bysporophyte and microscopic gametophyte (Hori,photosynthesis (Nakashima 2002). The characteristics1993), and both life stages are able to culture inof DSW are, 1) rich nutrients: nitrate, phosphate andour laboratory. Mother sporophytes was culturing

silicate concentrations of DSW is higher than thatin polycarbonate vessel (1kl volume) with DSWof surface sea water (SSW), 2) cleanness: dissolved

and aeration. Usually these sporophytes matureorganic matter, sustained substances, almost noFig. 2. Fluctuation of nitrate concentrationin Suruga Bay deep-sea water (397m: brokenline; 687m: dotted line) and surface sea water(solid line) in 2007.

Fig. 3. Changes of the blade length ofjuvenile
sporophyte cultured inSuruga Bay deep-sea water (397m: ▲ ; 687m:○ ) and surface sea water ( ● ).

Seedling production inusing Suruga Bay deep-sea water for restoration of kelp beds in isoyake areaFig. 4. Photographs of seedling production. A: Propagation of the gametophytes, B: Homogenateof gametophytes, C: Strings wound on the triangular frame, D: Cultivation of seed strings, E:
Microscopic sporophytes on seed string (scale bar indicates 2cm).

in autumn, and we obtained zoospores from sori

These sporophytes were scattered on the strings

formed on the blades. The zoospores were cultured(approximately 1 mm in diameter) wound on theunder 40 〜 60μmol ms (light: dark cycle=12hr:

triangular frame made from vinyl chloride pipe (Fig.

12hr) at 18℃ in filtered and autoclaved seawater.

4 C) in the same vessel filled with DSW. DSW was

After the zoospores differentiated to male andfiltered with cartridge filter (pore size: 0.45μm)

female gametophytes. The gametophyte wereto prevent propagation of contaminated algae andcultured under 20 〜 80 μmol m‑2‑1s (light: darkorganisms because DSW contains a little number

cycle=12hr: 12hr) at 18℃ with gently stirring orof the microphytes. After the sporophytes werebatch culture in modified Provasoli s enrichedsettled on the strings, they were cultured in filteredseawater (PESI) without iron (Fig. 4 A). Maturation

DSW at approximately 80μmol m‑2 s‑1(light: dark‑1cycle=12hr: 12hr) at 12 〜 17℃ for about 1 month‑2‑1of the gametophyte is needed iron above 2.0 mg lin()(Motomura1981), and we observed same phenomenon in(Nimura2005). We could stock thegametophytes for several years in this condition.

(Fig. 4 D). As a result, we obtained a large numberof the macroscopic sporophytes on the strings (Fig.
4 E). Seeds on strings were cultured for acclimationin the sea under natural condition (Fig. 5 A). One or

Seedling production was started by thetwo weeks later, seed strings were wound to a ropehomogenization of the cultured gametophytes. Theand attached to the concrete reef (Fig. 5 B, C). The

gametophytes were homogenized with the mixer

concrete reef was set into Isoyake area (Fig. 5 D).

to cut into pieces of the filamentous gametophytes(Fig. 4 B). These gametophytes were cultured in

We produced theand other species, for example,

PESI with gently stirrer or aeration under 40 〜 60(μmol m‑2 s‑1 (light: dark cycle=12hr: 12hr) at 18℃.
After 1 〜 2 weeks later, we could obtain numerous
numbers of the microscopic free living sporophytes.

seedlings using DSW,),

These seedlings can be also used for thecultivation.

Kazumi NIMURA, Hiroyuki NODA and Kazutoshi OKAMOTO

Fig. 5 Photographs of transplanting, A: Cultivation of seed strings in the sea under natural
condition, B: Rope wound with seed strings, C: Concrete reef attached with the rope, D:
sporophytes derived from the seed strings on the concrete reef.

Acknowledgment

Nakashima T. 2002: What is deep sea water? inUtilization of Deep-sea water . Midori Shobo,

This study was partially supported by Isoyake

Tokyo. pp. 68‑91 (in Japanese).

Recovery Emergency Project , Fisheries Agency.

Nimura K., Okamoto K., Takase S., 2005: Effect ofWe would like to thank stuff of Suruga Bay deep-sea

Suruga Bay deep-sea water on the growth andwater aquaculture research center of Shizuoka

maturation of gametophytes ofprefectural research institute of fishery.

Areschoug (Phaeophyceae).
6(1), 35‑40 (in Japanese)

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