摘要
以我国黄渤海主要致灾大型水母海月水母的螅状体为实验材料,采用实验生态学方法研究了温度、盐度、光照强度、饵料量对其存活与繁殖的影响。结果表明,在0—25℃范围内,螅状体40 d的成活率均为100%,螅状体相对繁殖速度随温度的升高而增加;盐度在15—40范围内,螅状体40 d的成活率均为100%,盐度22.5组的螅状体相对繁殖速度最高,但盐度对螅状体种群数量影响不显著;螅状体相对繁殖速度随光照强度的增加而下降,黑暗条件有利于海月水母螅状体个体数量增加;螅状体相对繁殖速度随饵料量的增加而增加。研究结果说明海月水母螅状体对环境具有较强的适应性,水温升高、饵料量增加可导致海月水母螅状体种群数量快速增加。
Jellyfish blooms cause problems worldwide, and their outbreaks have been reported at unprecedented rates in the recent decades. The blooms of Aurelia spp. have become increasingly prominent worldwide since the end of the 20th century, causing serious damage to fisheries, marine ecosystems, and coastal power plants. Environmental factors that control the size of jellyfish populations are not well understood; however, many researchers suggest that global warming, water pollution, and overfishing may be the main factors. Many scyphozoan species, including Aurelia spp., have a benthic polyp stage. This stage is an important part of the life cycle of Aurelia spp., because polyp clones can increase their population size by asexual reproduction, providing the opportunity to increase the medusa population by the production of many ephyrae through strobilation. Environmental factors that affect the asexual reproduction rates include temperature, salinity, light, and food. In this study, polyps of Aurelia sp. 1, collected from Heishijiao, Dalian, China, were tested using various environmental factors：（1） 11 different temperatures （0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, 22.5, and 25℃） at salinity 28; （2） 14 different salinities （7.5, 10, 12.5, 15, 17.5, 20, 22.5, 27.5, 30, 32.5, 35, 37.5, and 40） at ambient temperatures （15-25℃） and natural light conditions; （3） 5 different light intensities （0, 200, 400, 600, and 800 lx） at 20-25℃ and a 10-h light/14-h dark photoperiod; and （4） 5 feeding frequencies （1 time/1 day, 1 time/2 days, 1 time/8 days, 1 time/16 days, and no feeding, which represent 8.3, 4.2, 1.0, 0.5, and 0 μg C per polyp/day） at 15-25℃. Asexual budding was strongly affected by temperature, feeding frequency, and light intensity, but it was not affected by salinity. The production of new buds increased dramatically with increasing temperatures, particularly in the range of 12.5-25℃. The asexual reproduction rate was the highest at salinity 22.5, and it gradually decreased as the salinity increased or decreased; however, the statistical results did not show any significant influence. Dark or dim light conditions greatly favored asexual reproduction, while bright light inhibited it. Asexual budding significantly decreased with decreased feeding frequency; a total of 9-59 buds were produced by feeding 1 time per day, and the number of buds decreased to only 1-3 by feeding 1 time per 14 days during the 60-day experiment. No polyps died even under no feeding conditions, which demonstrated that Aurelia sp. 1 polyps have a strong resistance to starvation. Survival was high in all the treatments, except in the salinity range of 7.5-12.5; this indicated a wide tolerance to environmental conditions. All these results indicate that the environment of the Bohai Sea and Yellow Sea is suitable for the survival and reproduction of Aurelia sp. 1. We suggest that increased temperatures because of global warming, increased abundance of zooplankton prey because of eutrophication, and increased seawater turbidity caused by industrial pollution may be responsible for the prominent blooms of Aurelia sp. 1 medusae in the coastal waters of the Bohai Sea and Yellow Sea.
出处
《生态学报》
CAS
CSCD
北大核心
2017年第4期1309-1317,共9页
Acta Ecologica Sinica
基金
辽宁省自然科学基金(2015020795)
国家重点基础研究发展计划(973)项目(2011CB403601)
国家自然科学基金(31400406)
关键词
大型水母暴发
无性繁殖
温度
盐度
光照强度
饵料量
jellyfish bloom
asexual reproduction
temperature
salinity
light intensity
feeding rate
