**7. Conclusion**

206 The Dynamical Processes of Biodiversity – Case Studies of Evolution and Spatial Distribution

Three species we discuss (*S. bongardiana, S. dentigera* and *E. fistulosa*) have different growth peculiarities, reproduction and demographic structure of the populations, so the strategy of

For instance, *S. bongardiana* may be harvested in the volumes of 50 % of its stock in each area (for Bering Island 0.5-0.75 thousand tons). The most expedient way of this species harvesting is cutting of algae in the intertidal zone during low tides using special knife (pruner) in 20 cm above the meristem zone at basal part of the blade. This provides fast re-growth of the blade and makes it possible to get aftercrop in 1.5-2 months, i.e. to carry out multiple

On the other hand the total harvest volume of *S. dentigera* should not exceed 30 % of the total stock because algae of this species grow much slower than *S. bongardiana* but have longer lifetime (presumably, 4-5 years of *S. dentigera* versus 2-3 years of *S. bongardiana*). Inasmuch as *S. dentigera* grows at considerable depths and constitutes a major part in cast ashore algae, collection of fresh samples of *S. dentigera* from the stormy beached seaweed mass seems to

Harvesting of *E. fistulosa* is possible from the boat by wrapping floating parts of the plants round long hook (kanza). For the sake of fast restoration of the stock it is expedient to cut them at the depth less than 1 m from water surface. Owing to high growth rate of the fronds of *E. fistulosa* it is possible to harvest phytomass several times during one vegetation season. Plants are able to reproduct successfully because the lower parts with sporophylles are not damaged. Annual estimated yield of *E. fistulosa* for Bering Island comes to 120 thousand

It should be accentuated that the use of dragrope is inadmissible in seaweed harvest as it causes considerable loss of raw material, damage of substratum, death of juvenile plants and as a result – elimination of thickets of algae. Moreover torn off plants sink and form dead bottom sediments, in the process of decay they reduce hydrogene contents in the near-

Recommended by us methods of brown algae harvesting at the coasts of Commander Islands satisfy the international requirements of exploitation of seaweed resources and do not conflict with the nature protection regime in the region. They are ecologically justified because produce no negative effects on the benthic marine ecosystems and populations of marine mammals. It is necessary to take into account the depths of algal vegetation and water temperature in order to fix optimal period of harvest in each specific area. According to our data the most favourable time of seaweed harvest on Bering Island is May-June. Plants growing in shallow water areas develop more rapidly and start reproduction earlier owing to faster water warming-up than algae growing in deeper areas. That is why first of all seaweeds from shallow water zones should be harvested. According to my calculations in the intertidal zone of Commander Islands it is possible to get 3-5 kg from m2 and in the

As far as the continental part of Bering Sea is concerned the present-day information on its seaweed resources is practically absent. That is why I would like to withhold recommendations on organization of harvest in this area. Commercial catch of seaweeds without scientific grounds at contemporary technological approach may cause irreplaceable losses of seaweeds and even destruction of the benthic communities. I think that studies on biodiversity of the western part of Bering Sea and ensuring of effective work of SPNA-s

their harvest should be different.

harvesting during a vegetation period.

be the most rational method of its harvesting.

upper sublittotal zone – up to 10-12 kg of raw seaweeds.

should precede organization of seaweed harvesting in the area.

tons.

bottom water layers.

Inventory of marine flora of the Russian sector of North Pacific is necessary not only for clarification of scientific problems of phycology but also for solving of some important practical problems. In particular, there is a threat of decrease of biodiversity of the region and loss of the still unknown species. Already known rare species included in the Red Data Book of Kamchatka (Selivanova, 2007) are also under the threat of loss. So I consider it very important to continue studies on biodiversity of marine coastal ecosystems of Bering Sea paying special attention to their plant components that form basic environments for valuable commercial objects (herring, rock trout, sea urchins etc.). In order to prevent their loss or decrease of number it is necessary to organize valid protection of resources of the shelf of the area. I am confident that sustainable harvest will make it possible to avoid destruction of marine ecosystem integrity and provide restoration of natural seaweed resources and their long-term exploitation. This will help to supply population of Kamchatka Region with this valuable food and technological natural raw material and organize its export to other areas of Russia and abroad.
