Predation efficiency in visual and tactile zooplanktivores

Abstract

Gelatinous zooplanktivores (medusae, siphonophores, and ctenophores) and visual zooplanktivores (fish) interact through competition, predation, and commensalism. In the search for key factors governing the outcome of competition, we examined the instantaneous predation efficiency and its light dependency. The visual predator Gobiusculus flavescens and the tactile predator Bolinopsis infundibulum were used as experimental models for the two predation modes. The predation rate of G. flavescens was adequately described by Holling's curvilinear disc equation, and that of B. infundibulum was proportional to prey density. However, because of superfluous feeding, the feeding rate of B. infundibulum differed from the predation rate and approached the asymptotic limitation at high prey levels. The predation rate was reduced for G. flavescens at irradiances Ͻ5-10 mol photons m Ϫ2 s Ϫ1, whereas light had no significant impact on the feeding pattern of B. infundibulum. Provided sufficient light, the predation rate of G. flavescens was several orders of magnitude higher than that of B. infundibulum. These results are consistent with the results of other studies, which suggests that the maximum clearance rate (C max ) of visual and tactile predators is described by the power functions C max ϭ 3.42 ϫ 10 Ϫ7 L 2.94 and C max ϭ 6.02 ϫ 10 Ϫ8 L 1.77 , respectively, where L is the length of the organisms in centimeters. We conclude that visual predation is most efficient at high visibility and low prey densities. As visibility decreases and prey density increases, the competitive efficiency of tactile predators increases.

Cambios interanuales en la biomasa y biodiversidad de zooplancton gelatinoso en aguas interiores de Chiloé, sur de Chile (primaveras 2004 y 2005)

“…Entre ellos, se indica que a menudo la eutroficación causa un aumento en la biomasa de cnidarios en desmedro de su diversidad (Arai 2001), mientras que el aumento en la turbidez reduce la visibilidad y puede dar una ventaja competitiva a los depredadores gelatinosos táctiles sobre los depredadores visuales (Eiane et al 1997, Sørnes & Aksnes 2004. Sin embargo, no hay estudios que indiquen que las aguas interiores de Chiloé presenten un aumento significativo en la perturbación antropogénica, que sea responsable de las variaciones interanuales en la biomasa gelatinosa.…”

Faking Giants: The Evolution of High Prey Clearance Rates in Jellyfishes

“…High fishing pressure on fish would favor a shift toward the competitively inferior jellyfishes (11). Contrasting competitive abilities between fishes and jellyfishes have been attributed to feeding differences among visual and tactile predators (12). Most economically relevant fishes and trophically dominant jellyfishes are cruising predators, which hunt while swimming.…”

Bacterial bioluminescence as a lure for marine zooplankton and fish

“…2), both sources are likely to occur in nature and are not mutually exclusive. Artemia was used in this study as a surrogate for actual zooplankton prey because it is readily eaten by zooplanktivorous fishes (31)(32)(33)(34)(35), is easy to handle, and lacks evasive behavior. The third characteristic was expected to reduce the variability of successful predation by the fish, allowing better separation of the effect of luminescence in our predation experiment.…”