| In the present study, we investigated the annual change of photosynthetic pigment contents of Zostera marina in Swan Lake and studied the effect of transplanting stress on the photosynthetic pigment contents of Z. marina. We also studied the effects of different sediment grain sizes and current velocities on the growth and photosynthetic pigment contents of Z. marina, and found out the adaptive ranges of sediment grain size and current velocity. The findings of the research will enrich the knowledge of the seagrasses photosynthetic physiology and provide data for the further study on the ecological restoration of seagrasses. The most results are summarized as follows:1. To investigate the annual change of photosynthetic pigment contents of Z. marina L. in Swan Lake, Z. marina were sampled from April 2009 to March 2010. Photosynthetic Pigment of Z. marina were extracted with soaking method and measured with the Spectrophotometer method. Results in the present study showed that the maximum of the total chlorophyll content was 2.40±0.034 mg/g observed in October and the minimum was 1.22±0.028 mg/g observed in June. The maximum of the content of chlorophyll a was 1.58±0.020 mg/g observed in October and the minimum was 0.76±0.036 mg/g observed in March. The maximum of the content of chlorophyll b was 0.83±0.016 mg/g observed in October and the minimum was 0.40±0.005 mg/g observed in January. The maximum of the content of carotenoid was 0.39±0.006 mg/g observed in January and the minimum was 0.13±0.004 mg/g observed in April. Based on the seasonal analysis, the contents of chlorophyll were higher during the late-autumn and early-winter, but lower in summer. The content of carotenoid was higher during the late-autumn and winter, but lower in early-spring and late-summer.2. The eelgrass Z. marina is transplanted using the method of stapling in Swan Lake in April 2009. Photosynthetic pigment contents of Z. marina transplants and nature are measured to study the effects of transplanting stress have on monthly from May to October. The results in the present study show that contents of chlorophyll a, chlorophyll b and total chlorophyll of Z. marina transplants are lower than those of nature Z. marina on May and October and there is a very significant difference between them (P<0.01). However, these contents of Z. marina transplants are higher than those of nature Z. marina on June, July, August and September and there is a significant difference between them on July and September (P<0.05). There is a different change in contents of carotenoid. Contents of carotenoid of Z. marina transplants are lower than those of nature Z. marina on May, June and September and there is a very significant difference between them on May (P<0.01). However, these contents of Z. marina transplants are higher than those of nature Z. marina on July, August and October and there is a significant difference between them on July and August (P<0.05). The findings of the research will improve our knowledge on some aspects of the physiology adaptation mechanism of seagrasses exposed to transplanting stress.3. Growth and photosynthetic pigment contents of Z. marina exposed to five different sediment grain sizes 0:1 (Sediment 1), 1:3 (Sediment 2), 1:1 (Sediment 3), 3:1 (Sediment 4), 1:0 (Sediment 5), and 3:2 (Control, from nature sea area) in the mass ratio of sand to mud) are indicated in Swan Lake of Rongcheng city, Shandong province in May 2010. Samples are collected monthly from June to November. Then, the morphological characteristics (leaf length, leaf width, sheath length, rhizome node length and root length) and the photosynthetic pigment contents (chlorophyll a, chlorophyll b, total chlorophyll and carotenoid) are surveyed. Results in the present study show that the leaf length, leaf width, sheath length and rhizome node length are longer in Sediment 2 than in the other treatments, but root grows better in Sediment 4. The contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid are higher in Sediment 4. It shows that the photosynthetic electron transport is decreased in the sediment with higher ratio in sand, and the eelgrass increases the contents of the photosynthetic pigments to maintain the photosynthesis. But the decrease of the net photosynthetic rate will slow down the growth of eelgrass.The research results will provide data for the selection in the suitable range of sediment grain size of seagrasses restoration sea areas and enrich the knowledge of the seagrasses photosynthetic physiology.4. In June 2010, four experimental areas of different current velocities are selected to study the effects of different current velocities on the growth and photosynthetic pigment contents of Z. marina in Swan Lake in Rongcheng city, Shandong province. The current velocities are 6.52±0.247 cm/s (Current 1), 8.24±0.405 cm/s (Current 2), 11.76±0.293 cm/s (Current 3) and 24.56±0.413 (Current 4). Samples are collected monthly from July to November. Then, the morphological characteristics (leaf length, leaf width, sheath length, rhizome node length and root length) and the photosynthetic pigment contents (chlorophyll a, chlorophyll b, total chlorophyll and carotenoid) are surveyed. Results show that both rhizome node length and root length are shorter in Current 1 (6.52±0.245 cm/s), but leaf length, leaf width, sheath length, rhizome node length and root length are longer in Current 2 (8.24±0.405 cm/s), indicating that Current 2 is the adaptive current velocity to the growth of eelgrass. The contents of chlorophyll a, chlorophyll b, total chlorophyll and carotenoid are higher in Current 1 (6.52±0.245 cm/s) and Current 4 (24.56±0.414 cm/s). It shows that the photosynthetic electron transport is decreased in the current with lower and higher velocity, and the eelgrass increases the contents of the photosynthetic pigments to maintain the photosynthesis. But the decrease of the net photosynthetic rate will slow down the growth of eelgrass.The research results will provide data for the selection in the suitable range of current velocity of seagrasses restoration sea areas and enrich the knowledge of the seagrasses photosynthetic physiology. |
PDF Full Text Request