濒危种螺蛳对典型附着藻的摄食特性及其在洱海流域恢复的可行性

Study on Margarya melanioides' feeding characteristics towards four attached algae and its potential restoration in Erhai basin

通过实验室小试研究濒临灭绝物种螺蛳(Margarya melanioides)对舟形藻(Naviculaceae sp.)、菱形藻(Nitzschia sp.)、孟氏颤藻(Planktothrixmougeotii)以及四尾栅藻(Scenedesmus quadricauda)4种典型附着藻类的摄食探讨其摄食生态学特性,调查海菜花(Ottelia acumiuate)养殖塘中藻的群落结构及水体的pH值、光照、溶解氧(DO)、温度等环境,从摄食生态学角度分析,探讨螺蛳在洱海流域恢复的可行性。摄食实验结果显示:螺蛳对实验选取四种藻摄食率关系为舟形藻>菱形藻>孟氏颤藻>四尾栅藻。对舟形藻摄食的影响因素研究结果表明在温度为25℃时其摄食强度最大,摄食率(IR)为(2.19±0.16)mg个^(-1)d^(-1);螺蛳在光照为0-100001x的范围内均有较强的摄食活动,摄食活动最适宜的光照强度区间为1000-20001x,摄食率IR均达到3.0mg个^(-1)d^(-1)以上;溶解氧DO对其摄食活动影响显著,当DO大于3.6mg/L时螺蛳摄食活跃,低于1mg/L时螺蛳基本停止摄食;螺蛳摄食率大小跟螺蛳重量呈显著负相关P<0.05。洱海流域海菜花塘水体的调查结果得出海菜花塘的pH值、光照、DO、温度以及藻等环境因子均适合螺蛳生存繁衍,可通过构建海菜花湿地来实现螺蛳的保种与扩增恢复。

Margarya melanioidesis endemic to the plateau lakes of Yunnan Province. In the early 1990s, it was the dominant benthiefauna species in the Lake Erhai basin. However, it is now facing extinction To further understand the feasibility of M. melanioides＇ restoration in Ottelia acuminate ponds within the Erhai basin from a feeding ecology view, the feeding ecology of the endangered snail towards four typical attached algae in the Erhai basin was studied using a small scale cultivation experiment. The algae were Navicula sp., Nitzschia sp., Planktothrixmougeotii, and Scenedesmus quadricauda. The feeding results showed that M. melanioides preferred to feed on Navicula.sp. under the same experiment conditions. The ingestion rate for the algae was as followed the order： Navicula sp. 〉 Nitzschia sp. 〉 Planktothrixmougeotii 〉 Scenedesmus quadricauda. The effects of the temperature, illumination, and dissolved oxygen （DO） on the ingestion rate of M. melanioides that weighed about 30 grams was studied by feedingthem Navicula sp. The results showed that all these factors had a significant impact on M. melanioides＇ feeding. A temperature rise from 10℃ to 25℃ increased the ingestion rate increased until it reached a maximum （2.19 ± 0.16）mg ind-1 d-l（ milligrams algae per individual per day） at 25℃ .It started to decrease when the temperature was higher than 2522. M. melanioides can normally act and eat under experiment illuminations from 0 lx to 10000 lx. The optimal illumination conditions were between 1000 lx and 2000 Ix, and within this range the ingestion rate can reached above 3.0mg ind-1 d-1 .M. rrManioides＇ feeding behavior was active when the DO was above 3.6mg/L, but virtually stopped when the DO was below 1.0 mg/L. The effect of M.melanioides＇ size on the ingestion rate was studied and the results showed a significant negative correlation （P 〈 0. 05 ） between them. The ingestion rate reached above 14.0 rag/ind-1 d-l.when M.melanioides＇ weight was within the range of 5 to 10 g, and was below 6.3 mg/ ind-1 d-1.when the weight was above 20 grams.Field investigations were carried out in Ottelia acuminate ponds located in the northern part of the Erhai basin. The environmental variables measured included DO, pH, illumination, temperature, aquatic biological structures etc. The results showed that DO was above 7.6 mg/L which meant that it had reached saturation levels, the pH was about 8.2, and the temperature was above 10℃ all year round （ It exceeded 2022 for almost half the year. It is worth mentioning that there were large amounts of Navicula sp., which indicated that the environment was suitable for M.melanioides. Ottelia acuminate wetland can therefore be used as a habitat for M. melanioides population restoration.