The Study About Ecological Remediation Of Intertidal Macroalgae Bed In The Non-residents Sea Islands

The sea islands without residents are a weak ecosystem because of simplestructure and enclosed spaces; however, they have very vital function in ecology,economy, military and scientific research. As the important part of sea islandsecosystem, intertidal zone has rich biodiversity with complex physiognomy andhydrologic features, where there are different species of macroalgae. The maroalgaebed, the starting point of the whole food chain, has high primary production and alsoplaya an important role in biogeochemical cycling. In recent years, environmentalpollution and human usage pose pressure on the natural condition of sea islands, andthe macroalgae of fixed growth suffered more damage when they could not escapefrom unpleasant factors. It was reported that lots of macroalgae had died in many seaisland, and large scale desertification had appeared. As a preferable biomarker, thereproduction and growth of macroalgae could reflect nearby environmental qualitydirectly; therefore, the biological remediation of macroalgae bed is of greatsignificance for the whole sea island system.This study firstly analyzed the situation of seawater pollution level andmacroalgae bed by the field survey, and selected intrinsic species based on themacroalgal investigation in the intertidal ozone of sea islands, and then carried on thestudy about the reproductive ecology on this kind under different concentrations ofnutrients and heavy metal. Meanwhile, the tolerance of different developmental stageswere researched in order to obtain the macroalgae which was able to be used inbiological remediation. The results show that:1The field investigation about non-residents sea islands（1） The field study was carried on in four sea islands located in Weihai includingSushan Island, Chu Island, Xiaoshi Island and Sanlian Island. The investigation datashowed that most physical factors kept stable, and only the value of pH had a increased tendency. The main pollutants were ammonium salt and Pb²⁺.（2） By the main effect analysis, nitrates, Cu²⁺ and Pb²⁺ had the worst impact onthe seawater. Sushan Island had better state of health, and Sanlian Island had the worst.Compared with historical data, the biomass and area of macroalgae had the obviousfall and at the same time, the original species despeared and dominant specieschanged. The bioremediation of macroalgae was extremely urgent.（3） As the dominant species, Sargassum thunbergii （Mertens） O’Kuntze（s.thunbergii） were selected to be the target used in the remediation.2The observation of s. thunbergii on the generative propagation（1） It was observed that the time of spores diffusion and generative propagationseemed to be short and zygote were easy to collect. The rhizoid of s. thunbergiigrew rapidly and could fix in48h after fertilization which seemed to be a survivalstrategies.（2）The juvenile sporophyte was easy to be effected by temperature than salinity;therefore it was better to control the temperature in order to raise the survival rate andgrowth rate during the experiment. There are many discrepancies in the gowth andreproduction for s. thunbergii between north and south compared with previousreports.3The effect of nitrogen and phosphorus nutrition and Cu²⁺on the early stage ofjuvenile sporophyte（1）The exposed test data showed that there was no lethal effect in early stage ofjuvenile sporophyte for nitrogen and phosphorus nutrition except the maximal dosegroup; however, the raletive growth rate and development were effected significantly.The development rate was maximal in the group of N:P=10:1.（2）Cu²⁺had notable impact on the growth and reproduction of early stages and forjuvenile sporophyte. Cu²⁺had excitant to the grown of juvenile sporophyte in theconcentration of0.05mg/L. When the concentration of Cu²⁺ is lower than0.1mg/L,there is no inhibition on the growth of juvenile sporophyte; Cu²⁺ has mortal effect onthe experimental juvenile sporophyte. The mortality rate of juvenile sporophyteincreases as the increase of Cu²⁺ concentration. The morphology of juvenile sporophyte also reacts to the increase of Cu²⁺ concentration, in terms of smallervolume, aggradation of pigments, lower light transmission, etc. All treated groups hadobvious lethal effect and the phenomenon of growth delay except the group with theminimal concentration, and all juvenile sporophyte died when the concentration ofCu²⁺was up to2.5mg L^-1.4The effect of nitrogen and phosphorus nutrition and Cu²⁺on the growth andproduction of adult macroalgaeWhen the adult macroalgae were under the nitrogen, phosphorus nutrition andCu²⁺, Cu²⁺had more significant impact on them.（1） The activity of Nitrate reductase （NR） increased while the level of nitrogennutrition rose, but up to high concentrations,the activities were be inhibited. Theactivities of Alkaline Phosphatase （AP） decreased with the increasing of phosphorousnutrition in groups of low levels(0,2.5μmol L^-1); however, there was adversetendency in high level groups.（2） When exposed to Cu²⁺, the content of chlorophyll increased at first and thendecreased as time while showed a trend of fluctuating download as the concentrationsof Cu²⁺.5The field remediation of intertidal macroalgae in non-residents sea islands（1）Direct pouring juvenile sporophyte was better than placing the medium withattached sporophyte because the tide could break up the medium and made it not easyto fix. Meanwhile, the rock were not smooth and lots of juvenile sporophyte were notable to fix.（2）Hence, manual handling to the rock was necessary, and then service played animportant role in later period in order to reduce other algae and mud.