Reproductive seasonality and early life temperature sensitivity reflect vulnerability of a seaweed undergoing range reduction
Reproductive seasonality and early life temperature sensitivity reflect vulnerability of a seaweed undergoing range reduction
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DOI：
10.3354/meps10567
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发表时间：
2014-01-01
影响因子：
2.5
通讯作者：
Wernberg, Thomas
中科院分区：
文献类型：
--
作者：
Andrews, Stefan;Bennett, Scott;Wernberg, Thomas
温度是海洋物种性能和地理范围的主要决定因素。因此，温度的变化可能导致局部死亡和物种分布的变化，但许多重要的栖息地形成海藻物种的物候和温度敏感性尚未被调查。通过野外观察和培养生长实验，研究了澳大利亚广泛分布的基础海藻Scythalia dorycarpa的繁殖时机、定居后早期生长和存活以及招募成功的温度敏感性。在养殖中，在15摄氏度时达到最高的定居密度和最低的死亡率，而种子受精的最佳温度出现在18摄氏度，而高于20摄氏度的温度推迟了胚芽的定居并显著增加了死亡率，在高于23摄氏度的温度下没有胚芽存活。实验结果与野外观察一致，发现当海水温度类似于18摄氏度时，成虫生殖发育和配子释放在整个冬季几个月以同步脉冲发生。对多年生草鱼新兵的纬向分布的调查显示，在较温暖的环境中，多年生草鱼的招募密度显著较低。夏季最高温度经常超过23摄氏度的低纬度珊瑚礁，与夏季平均最高温度为21至22摄氏度的较凉爽的极地珊瑚礁中的高得多的新成员密度相比，繁殖的时间、新成员的纬度分布和最适养殖温度都表明，在多年生草鱼的早期生活期中，对温度高度敏感。这些发现有助于解释这种物种在2011年澳大利亚西南海岸附近的一次海洋热浪之后活动范围迅速缩小的原因。
Temperature is a major determinant of the performance and geographical ranges of marine species. Changes in temperature can therefore result in localised mortality and shifts in species distributions, but the phenology and temperature sensitivity of many important habitat-forming seaweed species has not yet been investigated. Through field observations and culture growth experiments, the present study investigated the temperature sensitivity of reproductive timing, early post-settlement growth and survival, and recruitment success of the widespread foundation seaweed Scytothalia dorycarpa in Australia. In culture, the highest settlement densities and lowest mortality rates were achieved at 15 degrees C, and optimal temperatures for germling fertilisation occurred at 18 degrees C, whereas temperatures greater than 20 degrees C delayed germling settlement and significantly increased mortality rates, with no germlings surviving at temperatures greater than 23 degrees C. Experimental findings were consistent with field observations that found adult reproductive development and gamete release to occur in synchronous pulses throughout the winter months, when seawater temperatures were similar to 18 degrees C. Surveys of the latitudinal distribution of S. dorycarpa recruits showed significantly lower recruit densities in warmer, low-latitude reefs where summer maximum temperatures often exceed 23 degrees C compared to much higher recruit densities in cooler pole-ward reefs where average summer maximum temperatures are 21 to 22 degrees C. The timing of reproduction, latitudinal distribution of recruits and culture temperature optima all indicate high temperature sensitivity among the early life stages of S. dorycarpa. These findings help to explain the rapid range contraction of this species following a 2011 marine heatwave off the southwest coast of Australia.