温度对沉积物中绿藻微观繁殖体萌发的影响

摘要

对黄海浒苔绿潮的研究表明，苏北浅滩及其附近海域是每次绿潮早期发展的重要区域，石莼目绿藻微观繁殖体在该水域大量存在。为研究海水温度对其萌发和生长的影响，我们利用2012‐10在江苏近岸如东紫菜养殖区采集的沉积物样品，在实验室进行不同温度梯度条件（5，10，15，20，25和30℃）绿藻微观繁殖体的培养实验，并通过PCR‐RFLP方法鉴定繁殖体幼苗的种类，分析温度对不同种绿藻微观繁殖体萌发的影响。结果表明：5℃的低温条件下，繁殖体均不能萌发。10～30℃，随温度的升高繁殖体萌发数量呈先增加后降低的趋势。15和20℃时，萌发数量出现高值，分别平均为17．0和15．8株／g。在研究区域沉积物中绿藻微观繁殖体萌发种类有浒苔、缘管浒苔、盘苔和Ulvasp．1，其萌发数量的平均值分别为13．7，6．0，2．0和15．4株／g。其中，浒苔萌发数量随温度的升高先升高后降低，在15℃时达到最高值为31．2株／g。缘管浒苔在10～20℃萌发数量相对较高，25℃时极低（仅为1．6株／g ），而5和30℃时都未能萌发；U lv a sp ．1在10～30℃数量变化不明显，一直保持较高值在15．0株／g左右；盘苔萌发数量一直较低，在各温度下均小于3．0株／g。据估算，在苏北浅滩紫菜养殖区（约200 km2）表层沉积物中约有9．8×1013株微观繁殖体，形成一个巨大的“种子库”，这将为黄海浒苔绿潮溯源提供数据支撑。%Subei Shoal and its adjacent waters are important area for early development of Ulva prolifera green tides in southern Yellow Sea. It has proved that the micro‐propagules were extensively distributed in this water area and the sea water temperature could influence the germination and growth of micro‐propagules. The effects of temperature (5 ,10 ,15 ,20 ,25 and 30 ℃) on the species and germinating quanti‐ty of micro‐propagules of green algae in the sediment samples were studied in our laboratory using the sam‐ples collected from Porphyra aquaculture area in the southern Jiangsu province in October 2012. Results show that the algae micro‐propagules failed to geminate in 5 ℃. With the water temperature rose from 10 ℃ to 30 ℃ ,the quantity of micro‐propagules had a trend of first increase and then decrease ,its peak was recorded at 15 ℃ and 20 ℃ ,being 17. 0 ind. /g and 15. 8 ind. /g ,respectively. These micro‐propagules were identified as Ulva prolifera ,Ulva linza ,Ulva sp. 1 and Blidingia sp. by PCR‐RFLP ,the average amount of them were 13. 7 ind. /g ,6. 0 ind. /g ,2. 0 ind. /g and 15. 4 ind. /g. Among them ,the amount of micro‐propagules of Ulv a p roli f era reached the peak at 15 ℃ ,being 31. 2 ind. /g ,and those of Ulv a linz a were higher at 10~20 ℃ ,diminished to 1. 6 ind. /g at 25 ℃ and did not germinate at 5 ℃ or 30 ℃. The micro‐propagules of Ulv a sp. 1 maintained high amount at 10~30 ℃ ,being 15 ind. /g and those of Blid‐ingia sp. w ere in low amount in all temperature ,being about 3 ind. /g. Accordingly ,it was estimated that approximately 9. 8 × 1013 ind. micro‐propagules would be existed in the sediment of Porphyra aquaculture area in Subei Shoal (about 200 km2 ) ,which will constitute a huge seed bank of green algae. This study will contribute data to support the traceability of green tide in the Yellow Sea.