Wang Zeshuang, Huang Xiaoli, Wu Yangyang, Hu Xiang, Zhao Qihang, Zuo Jun, Xiao Peng, Cheng Yao, Zhang He, Li Renhui
National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, Zhejiang Provincial Key Lab for Water Environment and Marine Biological Resources Protection, Institute for Eco-Environmental Research of Sanyang Wetland, Wenzhou University, Wenzhou 325035, China.
College of Life Sciences and Technology, Harbin Normal University, Harbin 150025 China.
Harmful Algae. 2024 Aug;137:102678. doi: 10.1016/j.hal.2024.102678. Epub 2024 Jun 25.
Raphidiopsis blooms are notorious for cyanotoxin formation and strong invasiveness, threatening the stability of aquatic ecosystems and human health. The protozoa Paramecium can potentially serve as an organism for controlling Raphidiopsis blooms owing to its grazing effect. However, the grazing ability of Paramecium is largely determined by the size of the prey, and the population of Raphidiopsis consists of filaments of varying lengths and sizes. The selective grazing behavior of Paramecium toward short-length or small-sized filaments in the Raphidiopsis population, as opposed to long filaments, remains unclear. Therefore, in this study, we co-cultured the predator Paramecium sp. with different initial abundances and the prey Raphidiopsis raciborskii to explore this knowledge gap. Our results suggested that: (1) the population of R. raciborskii declined under the selective grazing effect of Paramecium sp. on short filaments, whereas R. raciborskii with long filaments survived; (2) the growth of Paramecium sp. feeding on the same abundance of R. raciborskii was reduced at higher initial abundances, whereas its carrying capacity exhibited an opposite trend; (3) under ingestion by Paramecium sp., the morphology of R. raciborskii developed in the direction of becoming larger, and higher initial abundances of Paramecium sp. intensified this process; (4) increasing initial abundance of Paramecium sp. aggravated the decline of R. raciborskii photosynthetic activity. Therefore, the grazing effect of Paramecium sp. on R. raciborskii mainly affects filaments of short length or small size. Collectively, these results clarify the inter-species interaction between the protozoa Paramecium and filamentous cyanobacteria Raphidiopsis, including population dynamics and morphological and physiological changes in the predator and prey. Such insights into the interactions between Paramecium and R. raciborskii may have implications for the biological control of blooms caused by filamentous cyanobacteria.
席藻水华因产生蓝藻毒素和强大的入侵性而臭名昭著，威胁着水生生态系统的稳定性和人类健康。原生动物草履虫因其捕食作用有可能成为控制席藻水华的生物。然而，草履虫的捕食能力很大程度上取决于猎物的大小，而席藻种群由不同长度和大小的丝状体组成。与长丝状体相比，草履虫对席藻种群中短长度或小尺寸丝状体的选择性捕食行为仍不清楚。因此，在本研究中，我们将捕食者草履虫与不同初始丰度的猎物拉氏席藻进行共培养，以填补这一知识空白。我们的结果表明：（1）在草履虫对短丝状体的选择性捕食作用下，拉氏席藻种群数量下降，而长丝状体的拉氏席藻存活下来；（2）以相同丰度的拉氏席藻为食时，草履虫在较高初始丰度下的生长受到抑制，而其承载能力则呈现相反的趋势；（3）在草履虫摄食下，拉氏席藻的形态朝着变大的方向发展，且草履虫的初始丰度越高，这一过程越明显；（4）草履虫初始丰度的增加加剧了拉氏席藻光合活性的下降。因此，草履虫对拉氏席藻的捕食作用主要影响短长度或小尺寸的丝状体。总的来说，这些结果阐明了原生动物草履虫与丝状蓝藻席藻之间的种间相互作用，包括捕食者和猎物的种群动态以及形态和生理变化。对草履虫与拉氏席藻相互作用的这些见解可能对丝状蓝藻水华的生物防治具有启示意义。
