Parvocalanus crassirostris is an important small calanoid copepod in coastal ecosystems and a promising live prey organism for marine fish larviculture. Its feeding selection and rejection behaviors toward different microalgal diets directly affect dietary utilization, reproductive performance, and population expansion. However, conventional dietary evaluations mainly rely on physiological endpoint indicators, such as ingestion rate, egg production, and population growth, making it difficult to directly reveal the immediate behavioral responses and selection mechanisms of copepods when encountering algal particles of different sizes and species. To address this gap, the present study selected three representative microalgae, namely Isochrysis zhanjiangensis, Rhodomonas sp., and Tetraselmis subcordiformis, and established monoalgal and mixed-algal dietary treatments. High-speed filming experiments were introduced as the core observational method to continuously record and quantitatively analyze swimming, jumping, resting, turning, and feeding-related behaviors of Parvocalanus crassirostris under different dietary conditions. Particular attention was paid to its approach, capture, ingestion, feeding refusal, and rejection behaviors toward algal particles of different sizes and species, with the aim of exploring the underlying causes of diet selection and rejection.This study simultaneously measured ingestion rate, reproductive parameters, and fatty acid composition to validate the feeding preferences of Parvocalanus crassirostris revealed by high-speed filming-based behavioral tracking from physiological and nutritional perspectives.
The novelty of this study lies in the application of high-speed filming-based behavioral tracking to the investigation of feeding preference in small copepods. This approach overcomes the limitations of relying solely on conventional physiological endpoint indicators for evaluating diet palatability and provides a continuous, direct, and quantitative method for studying plankton feeding behavior, particle recognition, diet selection, and nutritional responses. The findings are expected to provide a methodological basis for microalgal diet screening and formulation optimization in the artificial culture of Parvocalanus crassirostris, as well as technical support for the standardized cultivation of copepod live prey in marine seedling production.