Present situation, problems and perspective in Japanese Kelp cultivation in Russia

Victor V. Ivin

Institute of Marine Biology, Far East Branch, Russian Academy of Sciences
17 Palchevsky St., Vladivostok 690041, Russia

This matter was presented at the International Symposium "Earth - Water - Humans", Kanazawa, Japan: May 30-June 1, 1999

The Japanese kelp Laminaria japonica Aresch. is a valuable material for the manufacturing of alginates and mannitol; it is also used as food for humans and domestic livestock and in medicine. In the Far Eastern region of Russia, L. japonica is a major commercially important species and rank top among culture organisms . Japanese kelp has been cultivated in the Primorsky Territory for more than 20 years on three industrial kelp farms (Fig.1) and on a few experimental with an area of about 400 hectares. The preliminary survey has revealed an opportunity considerably to increase areas for laminarian cultivation. At present average crop capacity is 26 tons wet kelp per hectare. However, it is thought that the productivity can be increased up to 70 - 120 tons wet kelp per hectare.

1. Two-year floating raft method has the widest application on Russian kelp farms.
2. Forced cultivation is used only on experimental kelp farms.

There are several problems in cultivation of Laminaria.

Epiphytes on cultivated Laminaria.

Epiphytes cause the greatest harm to cultivated kelp. Various organisms develop on the L. japonica thalli. There are three main kinds of epiphytes which grow on cultivated kelp thalli, Hydrozoa (Obelia longissima), Bryozoa (Celleporella hyalina and Bugula pacifica nana) and Spirorbid polychaetes (Circeis armoricana and Neodexiospira alveolata) These epiphytes adversely affect the commercial value of Laminaria (Fig.2).

Reproduction of this species starts when its maximal diameter reaches 1.9 ± 0.1 mm at the age of about 2 - 3 months. Larval hatching and settling on substrate happens only at night. Maximal larval numbers occur at 5 a.m. o'clock in the morning. Settled spirorbids build their calcareous spirals with a diameter of 300 ± 10 microns. After 2 - 3 months settled animals reach their sexual maturity and begin reproduction.

The dynamics of spirorbids settling on cultured Laminaria has some peculiarities. Spirorbids are first found on young Laminaria (age 0 +) only at the end of May - beginning of June, i.e., 7 - 9 months after vertical ropes have been placed in the sea.

First spirorbids on Laminaria are observed in the lower part of ropes in near-shore kelp farms areas. Later on they occur in top ropes parts in all farms. In the summer the density of spirorbid settlement is increased. In September - October spirorbid tubes are found not only on thalli but also on stipes and rhizomes. At this time 100 % of plants on kelp farm are colonized by spirorbids, including small plants of about 2 - 3 cm in length. On second-year thalli spirorbids become abundant at the end of May - beginning of June, after increase of water temperature more then 4°C. The fouling of second-year Laminaria is more intensive as compared to first-year plants. Apparently, in the former case larvae source is considerably far from the kelp, while in case with second-year Laminaria larvae source is on the same kelp thallus.

This can also be explained by the fact that the fouling of first-year Laminaria begins later than in second-year plants. It i s likely that laminarian fouling depends rather on the change in kelp physiological state than on the periodicity of spirorbid reproduction. Though the spirorbids are constantly reproducing, larvae of this species do not settle on laminarian thalli, which intensively grow in winter and spring.

Grazers on cultivated Laminaria.

Grazers cause great harm to cultivated kelp. The main grazers on cultivated kelp are the gastropod snail (Epheria turrita) and Amphipoda (Ampithoe eoa). When grazers’ appearances on the kelp farm the quantity of the cultivated Laminaria is permanently lowered up to 85%.

The greatest harm to cultivated kelp is caused by E. turrita, a common epiphytic species in laminarian mariculture. Favorable conditions for periodic outbreaks of this species frequently arise in kelp monoculture if the planting density is too high. Sometimes their density on cultured Laminaria can reach up to 500 individuals per thallus.

The snails actively graze an average part of laminarian thallus. At first they affect the growth zone and then other parts of the kelp. Because of grazing thalli often break off, causing loss of a significant part of cultured Laminaria. Snails cause the greatest damage to young (first-year) Laminaria. Mollusks are distributed over the thallus in a random pattern.

The first gastropod spawn masses on laminarian thalli appear in middle January at negative water temperature (up to -1,4°C ). The mass reproduction begins in April at water temperature of up to 5°C and continues to the beginning of June. Juvenile snails occur on laminarian thalli at the end of June.At this time their shells are 0.7 ± 0.1 mm in height. The settlement peak of this species occurs in August (Fig. 3) at maximum water temperature (up to 23°C ). Average settlement density of E. turrita is 157.3 individuals per thallus, and sometimes up to 500.0 individuals per thallus.

By the beginning of spawning period (December - January) mollusks remain only on plants in the lower part of ropes (depth 6 - 7 meters). Their average density at this time is 1.6 individuals per thallus. As a result of swarms of mollusks, which have finished reproduction, their density continues to decrease.

In the beginning of June we did not find adult E. turrita. Thus, the life span of mollusks on cultured Laminaria is about 9 - 11 months. According to Golikov and Menshutkin (1971), the life span of this species is about three years.

Young mollusks, which have appeared in late summer, intensively grow and reach sexual maturity in the beginning of the next year. Thus, E. turrita attains sexual maturity at the age of 6 - 7 months. At this period average shell height is about 11.9 mm, average weight 0.1 g.

The diseases of cultivated Laminaria.

Diseases cause serious harm to cultivated kelp. There are very severe diseases yellow, white and green spots caused by fungi and some physiological conditions. Colonization and development of pathogenic fungi on L. japonica are related to the stage of development of the alga, its physiological state, cultivation technology and the state of the aquatic environment (Zvereva, 1998). If the planting density is too high in algal monoculture, fungi may cause various infection diseases (Limin, 1994).

Yellow spots were found on all the kelp farms. The maximal development of this disease (30 - 60% of cultivated plants) was observed in Rifovy Inlet, the “Anna” kelp farm (Fig. 1). On this farm the first symptoms of disease appeared on young sporelings in March - April. The maximal development of the disease achieves throw the year at the end of May (Limin, 1994).

In young plants (age about two months) the disease occurs turn yellow of cellular matter in places of infection. In 5 - 6 monthly-old sporelings the disease is occurs as small yellow spots with oval or ovoid and wrong form. Later on, an ulcer is formed in middle of a spot, which gradually enlarges and covers large areas of laminarian thallus.

Mature Laminaria show large oval yellow spots. Large red - yellow spots with more intensity colored yellow border are visible on both sides of the laminarian thallus. Mycelial spots are about 3 - 80 mm in diameter. These spots can merge and form continuous areas of affection. In most cases it results in the destruction of affected plant.

The quality of cultivated Laminaria.

There is a difference in quality between cultivated and wild Laminaria. The chemical composition of cultured kelp differs from natural especially the natural second-year-old plants. Cultured Laminaria, algae contain less wet substances than second-year-old plants. The reason for this deterioration is probably due to changes in the quantities of intercellular substances during rapid growth.

The fouling of the structures for Laminaria cultivation.

During cultivation, all structures are subjected to intensive fouling. Because of fouling, the weight of the structures and their resistance to flowing water is sharply increased, and their storm-resistance and life spans are reduced.

It is known that fouling community of mariculture structures acts as the accumulator of fouling organisms. It is also the main source of their larvae. During the formation of fouling community L. japonica is colonized by spirorbid worms C. armoricana. During three years on kelp farm is formed large spirorbids population. At the spirorbids breeding on kelp farm occurs it "selfinfection." Recommendations, based on the results of our previous studies have made it possible to lower 100 time laminarian fouling in culture (Ivin, 1995).

The environmental impact of Laminarian mariculture.

Cultivation has created negative environmental impacts, such as eutrophication, augmentation of harmful microorganisms and parasites, changes in hydrological regimes in bays, due to proliferation of maricultural structures and discharge of high levels of organic matter into coastal waters.

It is well known that up to 25-40 % of gross production of the Laminariales turns to particulate and dissolved organic matter. This matter is commonly accepted as detritus.

The vertical flux of particulate matter on kelp farm is characterized by

1. A great absolute value (up to 148.2 gm per square meter per day);
2. Great dependence on rough sea;
3. Fast sedimentation rates of dissolved organic matter produced by kelp (Table).

Table. The vertical flux of particulate matter and organic carbon on kelp farm and nearest bays (by Shulkin, 1987).

*   The numerator gives samples depth; enumerator gives total depth.
** The numerator gives measure under calm; enumerator gives measure under strong rough sea.

There are perspectives of Laminaria cultivation.

Today productivity of kelp farms has reached its maximum. It can further be enhanced by applying new methods, one of which is selection of heat-resistant forms for south regions and high productive varieties for boreal regions.

In the south regions per the warmest years the majority of thalli is blasted down to stipe. However along with completely destroyed thalli healthy ones (10 %) can be found under the same conditions. After obtaining seedlings from such thalli it is possible to obtain the heat-resistant kelp form.

One of promising methods is the crossing of the miscellaneous forms of the same species. For example, the depth variety of kelp L. japonica f. longipes has a significant mass. Crossing it with heat-resistant form that has a smaller mass; it is possible to obtain a new kelp variety for southern regions. Crossing selection and hybridization could enhance productivity up to 200 tons wet kelp per hectare. Some experts believe that kelp farms could yield annual production of 85000 tons wet kelp.

Polyculture of Laminaria and some mollusks, primarily mussels and scallops, deserves particular attention. It is known that the growth rate of Laminaria cultivated with mollusks is 2 times higher than usual.

Of much interest is use of cultivated kelps as biofilters for clearing sewage and improving of sanitary conditions of polluted areas.

References

Golikov, A.N.and Menshutkin, V.V. (1971). Modeling of production process in population of gastropod mollusk Epheria turrita (A. Adams). Reports of the USSR Academy of Sciences. 197(4), 944-947, (in Russian).

Ivin, V.V. (1995). Fouling in Laminaria japonica mariculture. In: Proceedings of the International Conference on Ecological System Enhancement Technology for Aquatic Environments "ECOSET-95". Tokyo, 495-500.

Ivin, V.V. (1997). Seasonal dynamics of intensity of reproduction and fertility in Circeis armoricana (St-Joseph, 1894) (Polychaeta). Bull. Mar. Sci., 60(2), 543-546.

Limin, V.A. (1994). Spatial distribution, injuriousness and symptoms of yellow spot affecting the cultured Laminaria japonica in Primorye. Izvestia TINRO, 131, 80-82, (in Russian with English summary).

Shulkin, V.M. (1987). Biogeochemistry of sea bottom landscapes of a coastal zone of a northwest part of Sea of Japan. In: Sea of Japan bottoms landscapes. Vladivostok, 82-95, (in Russian).

Zvereva, L.V. (1998). Mycobiota of the cultivated brown alga Laminaria japonica. Russian Journal of Marine Biology, 24(1), 19-23.

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