The Preliminary Research Of Habitat Characteristics Of Sargassaceae Kelp Bed In GouQi Island

Since the 20th century, with the development of countries'industrialized revolution and world trade rising, narrow coastal region carries on more and more population, and it has created large number of the contradictions and pressure between coastal environment, human population and natural resource. Firstly, owing to the needs of coastal factory developing, large numbers of domestic wastewater, industrial water was discharging into the sea, and it brought excessive nutrients of water column, water temperature rising around the outfall, excessive heavy metal content, too often marine navigation footprint. These human activities will lead to the phenomenon of seaweed community succession between low trophic level to high trophic level. Secondly, owing to the needs of land reclamation and pier construction, large number of rocky coastline had been changed. Marine benthic macro-algae lose surviving habitat, and the scale of kelp bed is further declining in the past. Furthermore, the rising of the CO2 content will cause the rising of surface water temperature, and the activities will disturb the biological rhythm of benthic macro-algae. Between-in niche competition coralline algae is gradually occupying in finite cultch. In addition, the behavior of arbitrary the seaweed cutted off had severely impacted on the process of kelp bed recession. Finally, after over-exploitation to rocky marine biological creature, the density of biological biomass around rocky island is currently very low, and the population of sea urchin is losing ecological balance and exist stock enhancement, happening on large number of grazing behavior, especially for young spores.Marine ecosystem of benthic macro-algae has ecological and economic function. For ecological function, benthic macro-algae can absorb into CO2 content, reducing global warming. Self-shading area formed by kelp canopy provide the shelter for juvenile fish to avoid the predator. Large number of caprellidea and mobile benthic fauna choose kelp bed as their habitats, and these fauna animal used as food for many important economic fish, especially for migrating fish annual year, just like the oasis of the desert. In addition, the leaf can absorb seawater nutrients, and finally it can improve seawater eutrophication and water quality. The interaction between the fronds of seaweed can buffer the wave action of seawater. The variation margin of water temperature of kelp bed inside is lower than kelp bed outside, and will be relative stability and provide feeding ground for juvenile fish. For economic function, the ecosystem of kelp bed is an open ecosystem. Marine food web and energy flow structure is related to seasonal factors. Fish will consider the needs of migrating and feeding, they will choose kelp bed as temporary location in the migrating route. Therefore, kelp bed can provide the service of marine food output to the society.Faced with serious declining of coastal kelp bed, the urgency works is to take action to gradually restore the population number and habitat area of Sargassum horneri kelp bed. This will improve the opportunities of population survival rate and population size. The reason of choosing Sargassaum horneri as the object of research is : 1) The community structure of dominant species is very simple, which is mainly composed of Sargassaum horneri (above 95% biomass), so the practice is flexible; 2) Sargassaum horneri is particular warm temperate species of the western of north pacific, so the practice is the standard model of kelp bed restoration. Therefore, before we take action to restore the kelp bed, we should take the habitat structure and energy flux pattern of kelp bed as a whole. The purpose of the works is providing the scientific instruction of the construction of kelp bed. Based on the biological resource, kelp resource, habitat characteristics of kelp bed from 2005 to 2010, we divided the research object into habitat evaluation, kelp growth, fish population utilization. According to the judgement of field observation and data analysis, we preliminarily got the habitat character of kelp bed in Gouqi island.The survey found that juvenile seedlings in August (estimated as 3320 ind/㎡) in HouTouWan is more than the month of May to June (estimated as 100 ind/㎡). During the period which cause is the loss of large number of juvenile seedlings? The results show that light is the main limiting factor of kelp growth. Through the competition of plant morphology such as increasing the number of the branch, the number of leaves and leaf surface area, the strategy will improve the opportunities of the kelp spores. Little light, sea urchin grazing and virus infection will cause small size of the seaweed or being loss. Therefore, before we take action to restore the kelp bed, the density of kelp and the water depth of cement board is key limited factor. The water depth of cement board is controlled by 2 meters.In NanJi island, the practice show that Sargassaum horneri is sexual reproduction, and some of broken branch is vegetative propagation. Which mechanism is promoting the propagation of Sargassaum horneri? The results show that the rhythm of kelp growth is related with temperature. From May to June every year, about 18~20℃, after the growth of the frond is growing by 1.8~2.2 m, the kelp will release egg. Meanwhile, because the kelp is taken off the rock in the role of canopy water resistance, the offspring will share more rocky area and light resource. Therefore, in the practice of restoration, the works will increase the total area of rocky coastline, and deeping the water depth. The purpose of work is to expand the scale of kelp bed and to delay the time of taking off the rock.The survey found that the attach to the frond closing surface is covered by the population of Ulva L. In the low-transparency of the water or sediment or deep water, it shows that Sargassaum horneri is varying degrees of virus. Near the narrow gap, there exists 8~12 sea urchin. However, there is no existing sea urchin in the location of the growth of Sargassaum horneri. This show that the growth is scale effect, and the plant avoid the factors of sea urchin grazing, virus infection. Adequate population scale is to promise the survive of population.The results show that steep slope will not be benefit to kelp attachment, and torrent or slow current will not be benefit to kelp growth. Slope at 40°will be benefit to the kelp attach.The growth model is W = aLb ( a,b<2). From the model, we know that when primary lateral will increase by 10 cm, leaves surface improve 1 times. More the number of branches is, more the number of leaves in the top of surface is.To adapt to the environment, there are 3 judgement mechanism for♀:♂.The following is : 1) to improve the survival opportunities of offspring,♀:♂of Sargassaum horneri>4, the number of♀is more than♂;2)♀:♂of Sargassaum horneri=1,the population is in balance;3)♀:♂of Sargassaum horneri<1(about 0.8),the scale and limited attached area is self-sustain to avoid intensive competition of offspring.