Seasonal variations in copepod size: effects of temperature, food abundance, and vertebrate predation

• Published in: Journal of plankton research 1986, Vol.8 (5), p.841-853
• Main Authors: Warren, Glenn J., Evans, Marlene S., Jude, David J., Ayers, John C.
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Animals; Autoecology; Biological and medical sciences; Cyclops bicuspidatus thomasi; Diaptomus minutus; Freshwater; Fundamental and applied biological sciences. Psychology; Protozoa. Invertebrata
• ISSN: 0142-7873; 1464-3774
• DOI: 10.1093/plankt/8.5.841

Seasonal dry weights of female and male Cyclops bicuspidatus thomasi, Diaptomus ashlandi and Diaptomus minutus were studied in southeastern Lake Michigan during 1975–1981. Smallest animals occurred during summer and early fall, and largest animals in winter and spring, a pattern reported for other copepods. The range of weights for the species and sexes decreased from winter to summer, and converged in summer to a value of approximately 2 μg/animal. Surface water temperature and abundances of young-of-the-year (YOY) fish were inversely correlated with weights of males and females of the three copepod species. Standing stocks of important phytoplankton groups, especially pennate diatoms and flagellates, were positively correlated with copepod weight. Seasonal change of copepod body size appears to be more than simply a function of temperature; seasonal predation by YOY fish may be a factor influencing sizes of adult copepods.