其他摘要 | Green-tide has become an ecological problem worldwide, and it has been occurred in most of the coastal states in the world. Ecology observation and nutrients analysis has been carried out focusing on four alga, namely, Ulva prolifera, Ulva intestinalis, Ulva lactuca, Ulva pertusa as main species inducing green tide. Moreover, the nitrogen stable isotope of Ulva prolifera, Ulva lactuca and Ulva pertusa collected in the intertidal zone of Yantai were analyzed. The purpose of our research is to elaborate the material fundament of specific algae arising green tide, and it is significant to avoid green tide, meanwhile reduce adverse impacts of the bloom of green alga on marine ecology environment and economic losses as the source of responsible suggestion. Samples of Ulva prolifera and Ulva intestinalis were collected from Porphyra yezoensis culture rafts in Nantong, Jiangsu Province in April, 2010. The growth characteristics of two species under different temperature and nutrients conditions were studied. The results showed that the relative growth rate of U. prolifera was high at the temperature between 15-25 ºC and high nutrient concentrations. In a comparison, the relative growth rate of U. intestinalis was higher at the temperature between 10-20 ºC and lower nutrient concentrations. It indicated that the algae’s biomass was mainly affected by their eco-physiological characteristics and adaptation to the changing environmental conditions. In March 2013, U. prolifera were collected in Rudong,Jiangsu. Additionally, U. intestinalis, U. lactuca and U. pertusa were sampled in intertidal zone, Yantai. This paper discusses impacts of different nutrient on the growth of four green alga and the experimental results demonstrate that: concerning ammonia experiment, the ammonia up take rates of U. prolifera, U. intestinalis, U. pertusaare were higher than the nitrate up take rates when the ammonia concentrations were between 100 μM and 500 μM; the growth of U. prolifera and U. intestinalis were restricted when the ammonia concentration was 1000 μM, but its did not have adverse effects on the growth of U. lactuca and U. pertusa. For nitrate experiment, there was an obvious decreased trend of the growth of U. pertusa. Nevertheless, the growth of U. intestinalis was increasing when the nitrate concentration was ranged from 50 μM to 1000 μM. About phosphate experiment, the growth of U. intestinalis was better in lower phosphate concentration (<15 μM) than in the higher concentration between 30 μM and 60 μM, meanwhile, the growth of U. pertusa did not change obviously when the phosphate concentration was under 30 μM. The respond mechanisms of phosphate need further study. Samples of U. pertusa, U. lactuca and U. prolifera were collected in Shigoutun and Yueliangwan in May 3rd, 2013. The nitrogen stable isotopic composition of the algae was analyzed. It indicated that both of the study areas were affected by human activities and the nitrogen emissions could be an important factor inducing green-tide. |
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