Roy Shovonlal, Bhattacharya Sabyasachi, Das Partha, Chattopadhyay Joydev
Agricultural and Ecological Research Unit, Indian Statistical Institute, Kolkata 700108, India.
J Biol Phys. 2007 Feb;33(1):1-17. doi: 10.1007/s10867-007-9038-z. Epub 2007 Jun 21.
We explore the mutual dependencies and interactions among different groups of species of the plankton population, based on an analysis of the long-term field observations carried out by our group in the North-West coast of the Bay of Bengal. The plankton community is structured into three groups of species, namely, non-toxic phytoplankton (NTP), toxic phytoplankton (TPP) and zooplankton. To find the pair-wise dependencies among the three groups of plankton, Pearson and partial correlation coefficients are calculated. To explore the simultaneous interaction among all the three groups, a time series analysis is performed. Following an Expectation Maximization (E-M) algorithm, those data points which are missing due to irregularities in sampling are estimated, and with the completed data set a Vector Auto-Regressive (VAR) model is analyzed. The overall analysis demonstrates that toxin-producing phytoplankton play two distinct roles: the inhibition on consumption of toxic substances reduces the abundance of zooplankton, and the toxic materials released by TPP significantly compensate for the competitive disadvantages among phytoplankton species. Our study suggests that the presence of TPP might be a possible cause for the generation of a complex interaction among the large number of phytoplankton and zooplankton species that might be responsible for the prolonged coexistence of the plankton species in a fluctuating biomass.
基于我们团队在孟加拉湾西北海岸进行的长期实地观测分析，我们探讨了浮游生物种群中不同物种组之间的相互依存关系和相互作用。浮游生物群落分为三类物种，即无毒浮游植物（NTP）、有毒浮游植物（TPP）和浮游动物。为了找出这三类浮游生物之间的成对依存关系，计算了皮尔逊相关系数和偏相关系数。为了探究这三类浮游生物之间的同步相互作用，进行了时间序列分析。按照期望最大化（E-M）算法，估计了由于采样不规则而缺失的数据点，并对完整数据集分析了向量自回归（VAR）模型。整体分析表明，产毒素的浮游植物发挥着两种不同的作用：对有毒物质消耗的抑制降低了浮游动物的丰度，TPP释放的有毒物质显著弥补了浮游植物物种之间的竞争劣势。我们的研究表明，TPP的存在可能是大量浮游植物和浮游动物物种之间产生复杂相互作用的一个可能原因，这种相互作用可能是浮游生物物种在波动生物量中长时间共存的原因。
