温度与光照强度对浒苔孢子／配子放散和萌发的影响

摘要

通过比较不同温度和光照强度对浒苔（Ulva prolifera）孢子／配子放散和萌发的影响，来探究适合浒苔孢子／配子放散和萌发的温度和光照强度。实验结果表明，适宜浒苔孢子／配子放散的温度和光照强度范围分别为20～30℃和180～300μmol·m－2·s－1。在温度25℃、光照强度240μmol·m－2·s－1时，浒苔孢子／配子的放散量最大。浒苔孢子／配子萌发的适宜温度和光照强度分别为15～25℃和40～160μmol·m－2·s－1，最适温度和光照强度分别为20℃和120μmol·m－2·s－1。本实验揭示了黄海绿潮优势种浒苔繁殖与生长的环境响应过程，为进一步探索黄海绿潮暴发机制提供理论依据。%Massive green tide has occurred every year in the coast of the Yellow Sea since 2007 ,seriously damaging the ecological environment and becoming a sustained marine environmental disaster.The dominant species of the floating green tide in the Yellow Sea was identified as U.prolifera.Floating thalli of Ulva prolifera samples were collected from Rudong coast,Jiangsu Province. Firstly,for the release of U.prolifera spores/gametes investigations,five temperature treatments (15,20, 25,30,35 ℃),five light intensity treatments(0,60,120,180,240,300 μmol·m-2 ·s-1 )and all materials were subjected to a 12L∶12D photoperiod throughout the experiment.In the second experiment,to study the response of the germination of U.prolifera spores/gametes to temperature and light intensity,six temperature treatments (10,15,20,25,30,35 ℃)under 60 μmol·m-2 ·s-1,six light intensity treatments (0,40,80,120,160,200μmol·m-2·s-1)under 20℃and all materials were subjected to a 12L∶12D photoperiod throughout the experiment. The results showed that the suitable temperature and light intensity for the release of U.prolifera spores/gametes were 20-30 ℃ and 180 -300 μmol·m-2 ·s-1 ,respectively.The maximum released amount of U.prolifera spores/gametes was observed at 25 ℃and 240 μmol·m-2 ·s-1 .However,the released amount of gametophyte blade was significantly higher than that of sporophyte blade (P<0.05 ).Under the condition of 25 ℃and 240 μmol · m-2 · s-1 ,the released amount of U.prolifera sporophyte blade was 2.8 ×107 individuals whereas that of the U.prolifera gametophyte blade was 5.2 ×107 individuals,which was twice as much as that of the sporophyte blade.The suitable temperature and light intensity for the germination of U. prolifera spores/gametes were at 15 -25 ℃ and 40 -160 μmol·m-2 ·s-1 and the optimum values were found to be 20 ℃ and 120 μmol·m-2 ·s-1 .Under the condition of 60 μmol·m-2 ·s-1 ,the germination rate of U.prolifera spores and gametes at 20 ℃ were approximately 88.3% and 77.8% respectively,which were much higher than that of other temperature levels (P<0.05).The significantly lower germination rates were observed at higher temperature and no germination was found at 35 ℃.Under the condition of 20 ℃, the germination rate of U.prolifera spores and gametes at 120 μmol·m-2 ·s-1 were approximately 86.5%and 88.1% respectively,which were much higher than that of other light intensity levels (P<0.05 ).The significantly lower germination rates were observed at lower light intensity and no germination was found in dark condition. This study carried out a detailed investigation on the response of the release and germination of U. prolifera spores/gametes on temperature and light intensity,which would be helpful to study the blooming mechanism of green tide.