The effects of climate variability on zooplankton and basking shark (Cetorhinus maximus) relative abundance off southwest Britain

At small spatial scales basking sharks (Cetorhinus maximus) forage selectively on zooplankton along thermal fronts, but the factors influencing broader scale patterns in their abundance and distribution remain largely unknown. Using long‐term sightings data collected off southwest Britain between 1988 and 2001, we show that the number of basking sharks recorded was highly correlated with abiotic factors, principally sea surface temperature (SST) and the lagged effect of SST in the previous month, but only very weakly to zooplankton density. This suggests that the changes in number of basking sharks recorded over large spatio‐temporal scales are more closely related to the availability of climate‐driven thermal resources than prey availability, whereas the converse is supported by previous studies at local scales. Taken together, these results imply scale‐dependent behavioural responses in basking sharks, with small‐scale foraging movements linked by broad scale responses to temperature variation.     

14C-多菌灵在棉苗植株内的吸收、传导、分布和代谢研究

本研究采用~(14)C 标记的多菌灵,通过棉苗的叶部和根部两个途径分别给药处理,结果说明:多菌灵象其它许多内吸杀菌剂一样,在植物体中随蒸腾流可以在木质部内迅速传导,而在韧皮部内传导是相当微弱的。多菌灵在棉苗各个部位的代谢速度是不相同的。通过根部给药处理后14天,根部、茎部及叶部母体化合物(MBC)的含量分别为25.3%,32.3%和56.7%。多菌灵在棉苗根部降解速度最快,茎部次之,叶部最慢。多菌灵在棉苗中的整个代谢速度较缓慢,14天后仍有48.5%的原药留在棉苗中。其主要代谢产物是2-氨基-苯并咪唑(2-AB)和水溶性轭合物。