Effects of multigenerational rearing, ontogeny and predation threat on copepod feeding rhythms

Abstract

Marine planktonic copepods frequently exhibit diel feeding cycles coupled with vertical migrations. However, copepod feeding rhythms can be influenced by factors others than different food availability between layers. In this study we determined the changes in the diel feeding behaviour of two marine copepod species (Centropages typicus and Paracartia grani) through multigenerational laboratory rearing, ontogeny, and upon the exposure to predator chemical cues. The wild females of both C. typicus and P. grani showed marked feeding rhythms with higher ingestion rates at night. The diel rhythms of C. typicus were maintained in the first laboratory-reared generation (F1), suggesting maternal effects, but disappeared in the following generations. The P. grani females of a long-term culture (>10 years) also showed no differences in their day-night feeding activity. Ontogenetic variations were detected in the F1 generation of C. typicus: feeding rhythms were absent in naupliar stages, but adults fed more intensely at night. In the case of the cultured P. grani, in general none of the stages showed feeding rhythms. Laboratory-reared C. typicus (8-11 generations) did not recover back the natural cyclic feeding when exposed to jellyfish and fish exudates, indicating that either predation risk does not significantly affect their diel feeding activity or predator-induced responses in marine copepods might not involve chemical signalling. Our study confirms that feeding-related functional traits of marine copepods can experience quick multigenerational changes in the laboratory; consequently, cultured copepods might not be good models for studies involving their diel feeding behaviour.

Predation risk alters life history strategies in an oceanic copepod

“…One could expect that copepods’ ability to respond to predator cues would be reduced or lost after >65 generations in culture. Culture conditions with ample food select for continuous feeding and fast growth, and thereby against behaviors that reduce growth, such as diel feeding cycles (Tiselius et al 1995, Olivares et al 2020) and potentially predator avoidance. Moreover, the culture population likely differs from wild populations due to founder effects, genetic drift and inbreeding, which typically result in loss of genetic variation (Futuyma 2005).…”

Predator Chemical Cue Effects on the Diel Feeding Behaviour of Marine Protists

“…Similarly, the other protists studied also seemed to show a time-dependent weakening of their diel feeding rhythm, although at a much longer scale (years). The fading of a diel feeding rhythm in the absence of predators in the laboratory has already been documented for marine copepods [27], and the presence of fish has also been reported to sharply enhance their diel feeding cycle [28], although the role of chemical cues alone might not be so clear [29,30]. However, the physical presence of fish can induce changes in some behavioural and morphological traits of copepods.…”

First Report of Fecal Microflora of Wild Bar-Headed Goose in Tibet Plateau

“…It is reported that a variety of birds in the world constantly migrate from one place to another every year. They can migrate over vast geographical areas and cross biological and geographical boundaries ( 7 ). Birds can act as a source of infections for public health and animals through direct contact or as carriers of pathogens including avian and zoonotic pathogens and antibiotic-resistant bacteria ( 8 ).…”