Adaptive feeding behavior and functional responses in zooplankton

Abstract

Zooplankton may modify their feeding behavior in response to prey availability and presence of predators with implications to populations of both predators and prey. Optimal foraging theory predicts that such responses result in a type II functional response for passive foragers and a type III response for active foragers, with the latter response having a stabilizing effect on prey populations. Here, we test the theoretical predictions and the underlying mechanisms in pelagic copepods that are actively feeding (feeding-current feeders), passively feeding (ambushers), or that can switch between the two feeding modes. In all cases, individual behaviors are consistent with the resulting functional response. Passive ambushing copepods have invariant foraging behavior and a type II functional response, as predicted. When foraging actively, the species with switching capability change its functional response from type II to III and modify its foraging effort in response to prey density and predation risk, also as predicted by theory. The obligate active feeders, however, follow a type II response inconsistent with the theoretical prediction. A survey of the literature similarly finds consistent type II response in ambush feeding copepods, but variable (II or III) responses in active feeders. We examine reasons for why observed behaviors at times deviate from predictions, and discuss the population dynamics and food web implications of the two types of functional responses and their underlying mechanisms.

Foraging response and acclimation of ambush feeding and feeding‐current feeding copepods to toxic dinoflagellates

“…The density of A. tonsa in this filming experiment was high, up to 1 copepod mL −1 , which exceeds typical densities in nature although such high densities have been reported (Berasategui et al ). Previous experiments have, however, demonstrated that behavior of A. tonsa is independent of concentration even at these densities (Dur et al ; Kiørboe et al ).…”

“…At the population level, there is plenty of evidence that copepods may evolve tolerance to HA over just a few generations Dam 2003, 2004;Kozlowsky-Suzuki et al 2003;Jiang et al 2011). Rapid co-evolution may be one reason for the high diversity of potentially toxic substances produced by some dinoflagellates as well as for the diversification of chemical profiles between different strains of the same species.…”

Temperature-and sex-specific grazing rate of a tropical copepod Pseudodiaptomus annandalei to food availability: Implications for live feed in aquaculture

“…Prior testing for the response of P. annandalei to food concentrations and temperatures, we followed the prefood acclimation method described by Kiørboe et al () with minor modification. Specifically, copepods were kept in clean seawater overnight without food to empty the gut content.…”

“…Prior testing for the response of P. annandalei to food concentrations and temperatures, we followed the prefood acclimation DOAN ET AL. | 3865 method described by Kiørboe et al (2018) with minor modification.…”

“…To determine the food saturation concentrations for copepods, the study of functional responses is a suitable method that was used for several decades (e.g., Holling, 1966;Colin & Dam, 2007;Sarma, Jimenez-Contreras, Fernandez, Nandini, & Garcia-Garcia, 2013;Saiz, Griffell, Calbet, & Isari, 2014;Helenius & Saiz, 2017;Kiørboe, Saiz, Tiselius, & Andersen, 2018). The calanoid copepod genus Pseudodiaptomus has been commonly cultured with several microalgal species such as Chaetoceros muelleri (Puello-Cruz, Mezo-Villalobos, Gonzalez-Rodriguez, & Voltolina, 2009), Isochrysis galbana (Beyrend-Dur et al, 2011;Puello-Cruz et al, 2009), Tetraselmis chui (Rayner, Hojgaard, Hansen, & Hwang, 2017) and Skeletonema costatum (Lehette, Ting, Chew, & Chong, 2016).…”