The Choice Of Material And Shape Of Artificial Alga Reefs And The Elementary Investigation Of Attachment Of Algas

This paper reviews the advances in studies on the construction of domestic and foreign artificial reef and the enlightment for our country, the meaning of the construction of artificial alga reef, and the ecological meaning of sea-grass field and the construction of artificial sea-grass field. The thesis investigates especially the attachment and growth of algas, such as Ulvaceae, Enteromorpha, Sargassum thunbergii, Sargassum siliquastrum and Laminaria japonica on modules of 8 different materials and 4 different shapes. The thesis observes the attachment and growth of Laminaria japonica juvenile sporophytes on different light intensity and modules of materials. The paper researches the depth which satisfy the growth of Laminaria japonica. The results are summarized as follows:1. Advances in studies on the construction of foreign artificial reefJapan and America worked best on the field of artificial reefs. Japan began the research of artificial on 1950's, and the country makes the construction of reefs as country's career, invests every year. To this way, different reefs were thrown onto the sea, and big fish and sea-grass field formed. The sea-grass fields offer the habitats for the fish and seashell, profect the resource and have obtained the obvious economic efficiency. Japanese artificial reef enterprise's obtained many kinds of factors, and they were attention the country take to the artificial reef enterprise, high quality fisherman and the attitude and methods during the construction of artificial reefs.The American artificial reef's construction principle, the objective, the operation and the management method have the obvious difference with other countries. The construction of artificial reefs divided into two stages: spontaneous stage, science proof and approval permission stage. The America thrown many artificial reefs, but invested little than japan. They thrown many rejects as the artificial reefs. Futhermore, the commercial investments were developed, the enterprise participated in the investment and used the pattern which the investores managed and profited. 54 million people participated the fishing, and the industry accounted for 35% of the entire America fishery total output.The japanese and American success experiences have many enlightenment to our country's construction of artificial reefs. Firstly, the government must attach importance to this enterprise, enlarge the investment and construct enough scale reef body group to improve the oceanic environment. Secondly, our country legislates to leash the construction of artificial reefs. Thirdly, complete the plan proof and the research. Finally, strengthen the law enforcement, protect the oceanic ecology and the fishery resources.2. The meaning of the construction of artificial alga reefAt present our country coast alga field destruction is serious. In the process of alga field's rehabilitation, we may delivery artificial alga reefs. The artificial alga reefs can resume the sea-grass fields through following several mechanism. Firstly, provide the places for sea-grass attachment. Secondly, increase the space's complexity. Thirdly, attract each kinds of animals to form the balanced ecosystem. Fourth, form the alga superiority population in the short-term. The design of artificial alga reefs is an important and complex work in the construction and delivery of them. The shape and material of reefs must be taken into account. The concrete was the most commonly used material during the construction of reefs, and the coal ash, steel, the sulfur, the shell, the lumber and the manual composition material were all be used. Before 1970's, the construction of artificial alga reefs was extensive,namely put the worn ships and the blocks into the sea directly. In recent years, the design of reefs developed to the intensified direction. There were several tendencies as following. Firstly, the surface was concave-convex and the superficial and internal was vesicular structure. Secondly, the fertilizer was increased into the interior of reefs.Moreover, many national coasts dike involved the function of alga reefs. Its goal is to let the alga attach in its surface easy, and make the alga grow healthily. After the alga reefs were used, the coast alga group and the fish and shell enhanced increased obviously.3. The ecological meaning of sea-grass field and the construction of artificial sea-grass fieldThe sea-grass field which is one of the major contributors of oceanic primary production plays an important part in the oceanic ecosystem. The paper analyzes the important meaning from the angle of the ecology and reviews the problems during the construction of the artificial sea-grass field.4. The effects of substrates and light intensity on the attachment and growth of Laminaria japonica juvenile sporophytesThe effects of substrates (Glass, Mirror, PVC sheet, Asbestos sheet, Concrete without glass powder on its surface, Concrete with glass powder on its surface) and light intensity(natural light intensity, 2500lx, 1500lx, 500lx) on attachment and growth of Laminaria japonica juvenile sporophytes were studied at 9±0.5 0C at the seedling field and lab flumes. The results showed that the growth of Laminaria japonica juvenile sporophytes under different substrates and light intensity were significantly different(P<0.01). The Laminaria japonica juvenile sporophytes attached on PVC sheet was significantly better than those under other materials(P<0.05), and grew best on mirror. The growth of the Laminaria japonica juvenile sporophytes on mirror, asbestos sheet and concrete was significantly better than other substrates on light intensity of 2500lx, 1500lx and 500lx(P<0.05). The on substrate of mirror and fluctuant natural light was better than other experimental group(P<0.05). The experiment shown that fluctuant natural light and substrates which had coarse surface and can aggregate light was fit for the growth of the Laminaria japonica juvenile sporophytes.5. The elementary investigation of natural attachment of algas on artificial reefs of different materials and shapesThe experimental modules different materials and shapes were placed in the intertidal zones during 4.5 months. There were 3 phylums, 13 species algas which attached on the modules, and the dominant species were Ulvaceae and Enteromorpha. The results of experimental modules of different materials indicated that the algas attached best on the modules of concrete and coal ash, and the following modules were rubber, FADs, abalone and oyster shells. The algas attached worst on the modules of steel. The results showed that the attachment of algas on modules of different materials were significantly different (p<0.05). The results of experimental modules of different shapes indicated that the algas attached significantly better on protruding than sunken modules (p<0.05). There were some conjunctions between the attachment and the length of lamina of alga during experimental periods.6. The elementary investigation of attachment of juveniles of Sargassum siliquastrum on artificial reefs of different materials and shapesThe experimental modules of different materials and shapes were placed in the workshop, and the Sargassum siliquastrum spores attached on the modules. After some time, the modules were thrown onto the intertidal zones and the growth of juvenile sporophytes were observed during 3.5 months. The results of experimental modules of different materials indicated that the attachment rate of Sargassum siliquastrum on modules of different materials were significantly different (p<0.05). The juvenile Sargassum siliquastrum attached best on the modules of concrete and coal ash, and the following modules were oyster, abalone and clam shells and FADs. The juvenile Sargassum siliquastrum attached worst on the modules of steel and rubber. The results of experimental modules of different materials indicated that the attachment rate of Sargassum siliquastrum on modules of different shapes were significantly different (p<0.05). The Sargassum siliquastrum attached better on sawtoothed than cycloidal modules.7. The elementary investigation of attachment of juveniles of Sargassum thunbergii and Laminaria japonica on artificial reefs of different materials and shapesThe experimental modules of different materials and shapes were placed in the workshop, and the Sargassum thunbergii and Laminaria japonica spore attached on the modules. Afer some time, the modules were thrown onto the intertidal zones and the growth of juvenile Sargassum thunbergii and Laminaria japonica were observed during 2.5 months. The results of experimental modules of different materials indicated that the attachment of juvenile Sargassum thunbergii on modules of different materials were significantly different (p<0.05). The juvenile Sargassum thunbergii attached best on abalone shells and worst on the modules of steel and rubble. There were no significantly different on the attachment of juvenile Laminaria japonica on the modules of different materials (p>0.05). The results of experimental modules of different shapes indicated that the attachment of juvenile Sargassum thunbergii and Laminaria japonica on modules of different shapes were not significantly different (p>0.05).8. The elementary investigation of depth which satisfy the growth of Laminaria japonicaThe juveniles of Laminaria japonica were hung in the different depth from 1m to 10m. The results of experiment indicated that the average length of juvenile Laminaria japonica shortened and the rate(%) of rotten juvenile Laminaria japonica augmented significantly when the depth increased after 15 days (p<0.05). The average length of juvenile Laminaria japonica was 18.63 cm on 3 m. The average length was less than 20 cm when the depth was more than 3 m. The rate (%) of rotten juvenile Laminaria japonica was 50% on 3 m. The rate (%) of rotten was more than 50% when the depth was more than 3 m.