| This research chose 15 different points to sampling,detach and identify varieties of meiofauna and calculate the amount, abundance, biomass, production of them in April?June and October of 2015 ,January of 2016 in Hainan Dongzhai Port Mangrove.A:chl-a, pha-a, the amount of organic matters, moisture content, water temperature,salinity,pH are measured and the relationship between environmental factors and meiofauna in Hainan Dongzhai Port Mangrove in different. In addition, combined with the domestic research of mangrove meiofauna that the number of meiofauna in the sediments can reflect the organic pollution, with scientific theory and some practical value for environmental monitoring.According to these four sampling, content of organic matters in different site of mangrove types range from 25.22% to 93.41% which has an average of 46.6% and increase with increased distance from the shore in spring and winter. On the contrary,the same parameter appears to be a vary different trend in summer and autumn. It declines with the depth in the surface water range from 0cm to 8cm and the maximum emerge in a more shallow water in spring in average of 37.64%, but the content of organic matters is much lower in spring and winter. In summery, it appeared to be a trend increases at first and then decreases from spring to winter.The content of chlorophyll a in the mangrove species was 0.188-6.303?g·g-1, and the total average was 1.731 pg g-1 .On April 28, 2015 (spring),chlorophyll a content distribution is more uniform,a high concentration area formed near the water source of 14,15 sampling point near. Where the mangrove growth sparse, near the outlet gate of the 1,2,3,4 sampling point emerged a large range of low concentration area. The content of chlorophyll a was gradually decreasing from bank to shallow sea, and the chlorophyll a appeared to decrease in 0-8cm depth, the chlorophyll content achieve its maximum on the surface and the average chlorophyll content was 47.64%.From the seasonal changes, chlorophyll a content appeared to increases at first and then decreases from spring to winter.The content of chlorophyll a changed with the seasons. The average chlorophyll a content in summer and autumn was not high, and the content of chlorophyll a was lower in spring and winter,and the difference was not significant.The content of chlorophyll a in summer and autumn was higher than that in spring and winter.The distribution of pha-a and chlorophyll a is roughly the same and the contents of pha-a and chlorophyll a in sediments are affected by various factors such as nutrient, sediment type, sea water transparency, tide and temperature.In addition,the content of chlorophyll and chlorophyll a is related to the variety of sediments.The correlation analysis showed that the distribution of pha-a and chlorophyll a in 0-2cm,2-5cm, 5-8cm had a significant positive correlation (Pearson, s P<0.05).The correlation factors of organic matter, chlorophyll a, pha-a and water content were analyzed by Pearson's correlation analysis. The correlation between biological factors changes with the seasons. There were significant or extremely significant correlations between chlorophyll a and pha-a during four sampling.There was no significant or extremely significant correlation between chlorophyll a and organic matter content in quadratic sampling. There was a significant positive correlation between organic matter and water content in spring (Pearson, s r = 0.531; P<0.05). And a significant negative correlation between organic matter and water content in summer (Pearson, s r = -0.694; P< 0.05). Water content, temperature, salinity and pH had some correlation,which changed with the seasons.In the study area, we isolated and identified Nematoda, Copepoda, Polychaeta,Oligochaeta, Turbellaria, Rotifera, Halacaroidea, and Other small species of benthic fauna.The average dominance of meiofauna in the four sampling surveys was 94.78%,98.25%, 95.50% and 96.44%, respectively, and the average average biomass was 64.41% % (Spring=59.46%, summer=73.33%, autumn=64.72%, winter =60.14%), the average biomass was 128.70±48.99?g dwt10cm-2?110.11±19.19?g dwtlOcm-2?95.09±20.19?g dwt10cm-2?89.98±26.79?g dwt10cm-2.The distribution of meiofauna is close to the inland nearshore, near the tail of the tail - Changning tail to form a high concentration area, showing a trend from the near shore to the far shore gradually reduced. In different seasons, the horizontal distribution of meiofauna varies with the seasons, and the number of meiofauna varies at different sampling points, and there are differences in biological groups. Because the free nematode group dominant in quartic samplings,the horizontal level of its four seasons consistent with the distribution of small benthic animals' horizontal level. The other species of small benthic animals varied with the seasons, and the difference of each station due to the environment, mangrove species and the number of different groups.The results showed that there was no significant difference between the abundance of meiofauna in spring and summer, and there was no significant difference between the abundance of meiofauna in autumn and winter.There were significant differences in the abundance of meiofauna between spring, summer with autumn, winter(P <0.05), the latter of that is lower. The average percentage of meiofauna distributed in the vertical direction at 0-2 was 51.79% (spring = 66.08, summer = 41.29%, autumn = 43.33%,winter = 46.46%). The average percentage of 0 to 5 cm is 77.22%. Nematodes are mostly distributed in 0 - 2cm and 2 - 5cm. About 75% of the copepods are distributed in the sediments 0 - 2cm, and no copepods were found in the quadratic sampling of a small number of sampling points in the depth of 2-5cm, 5-8cm.The change of the number and type of space in the area of natural and artificial factors is different at different times. The main environmental factors which affect the quantity and species distribution are also changed,and the main environmental factors affecting meiofauna distribution are sediment particles, organic matter content, chlorophyll a, pha-a, water content, salinity, pH, water temperature and so on.It shows that there is a positive correlation between abundance of meiofauna and chlorophyll a (Pearson's r=0.684; P<0.05)?pha-a (Pearson' s r=0.694; P<0.05).According to BIOENV multivariate analysis, the dominant environmental factors in sediment are chlorophyll a,pha-a,salinity and pH.The abundance of meiofauna in summer was negatively correlated with the content of organic matter (Pearson, s r = -0.518; P <0.05), and had a significant positive correlation with water content (Pearson,s r = 0.622; P <0.05). The abundance of nematodes was positively correlated with water content (Pearson, s r = 0.616; P<0.05).In addition, other meiofauna and the investigation of environmental factors are not obvious. The inference is due to the potential effects of organic pollution, heavy metal pollution and anthropogenic effects.The water content in autumn was moderately related to the abundance of meiofauna, the abundance of nematode, the abundance of copepods and the abundance of hairy. The abundance of meiofauna was negatively correlated with salinity (Pearson, s r = -0.566; P <0.05), The abundance of nematodes was negatively correlated with salinity (Pearson, s r = -0.572; P <0.05). The main environmental factors which affect the quantity and species distribution of meiofauna are Chl-a?Pha and salinity.There was a significant negative correlation between the abundance of winter polychaetes and the chlorophyll a and pha-a. The abundance of oligochaeta was negatively correlated with the content of organic matter. The main environmental factors which affect the quantity and species distribution of meiofauna are organic matter?water content?water temperature and salinity. |
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