Seasonality of Oithona similis and Calanus helgolandicus reproduction and abundance: contrasting responses to environmental variation at a shelf site
Seasonality of Oithona similis and Calanus helgolandicus reproduction and abundance: contrasting responses to environmental variation at a shelf site
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DOI：
10.1093/plankt/fby007
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发表时间：
2018-05-01
影响因子：
2.1
通讯作者：
Atkinson, A.
中科院分区：
文献类型：
--
作者：
Cornwell, L. E.;Findlay, H. S.;Atkinson, A.
远海桡足动物Oithona similis和Calanus helgolandicus在地理分布范围上存在重叠，但在摄食方式、繁殖策略和体型上存在差异。本文利用西部海峡观测站L4 25年的时间序列数据，研究了环境变化下这些不同性状对桡足动物丰度和繁殖数量的季节性影响。在年周期内产卵率（EPR，卵雌（-1）d(-1)）的比例变化接近10倍，两种产卵率相近，但相似圆蝽的EPR仅为黑角圆蝽的11%。相似鲈的EPR最大值出现的时间与夏季海表温度升高的时间一致，这可能是由于温度依赖的育苗期。相反，播播产卵的绿僵菌EPR与净热通量和硅藻生物量的相关性更强，这两个参数都与春季浮游植物的繁殖有关。在这两个物种中，雌性体重与海温呈负相关，每摄氏度，黑角鳗的体重减少7.5%，而O. similis的体重只减少2.3%。最后，这两个物种的EPR、成虫和桡足虫丰度的季节性明显脱钩，表明繁殖和丰度的最佳条件发生在一年中的不同时间。
The pelagic copepods Oithona similis and Calanus helgolandicus have overlapping geographic ranges, yet contrast in feeding mode, reproductive strategy and body size. We investigate how these contrasting traits influence the seasonality of copepod abundance and reproductive output under environmental variation, using time series data collected over 25 years at the Western Channel Observatory station, L4. The proportional change in egg production rate (EPR, eggs female(-1) d(-1)) over the annual cycle was similar to 10-fold and similar for both species, although EPR of O. similis was only similar to 11% that of C. helgolandicus. The timing of EPR maxima for O. similis coincided with increased sea surface temperature (SST) in summer, likely due to a temperature-dependent brooding period. Conversely, EPR of broadcast spawning C. helgolandicus was more strongly related to net heat flux and diatom biomass, both parameters associated with the spring phytoplankton bloom. In both species, female body mass correlated negatively with SST, with a 7.5% reduction in body mass per degrees C in C. helgolandicus compared to just 2.3% in O. similis. Finally, seasonality of EPR and adult and copepodite abundance was strongly decoupled in both species, suggesting that optimum conditions for reproduction and abundance occurred at different times of the year.