Predator-prey relationship between the cyclopoid copepod Diacyclops bicuspidatus and a free-living bacterivorous nematode

Abstract

The potential of copepods as predators of free-living nematodes was tested by presenting Diacyclops bicuspidatus, a common holarctic cyclopoid copepod, with Panagrolaimus sp. as prey in the laboratory. Diacyclops bicuspidatus readily fed on nematodes of all size classes, including prey longer than itself. No size preference was observed. Handling times varied between a few seconds and several minutes, depending on the size of the prey. At different prey densities, the feeding rates of D. bicuspidatus followed a type II functional response. Starved D. bicuspidatus consumed up to 45.1 nematodes in 2 h, equivalent to 43.5% of the copepod's body mass. Indications that nematophagous nutrition is common among freshwater copepods are discussed.

Relation between nematode communities and trophic state in southern Swedish lakes

“…Besides their numerical dominance, nematodes are occupants of different trophic levels, comprising species that feed on bacteria, algae, fungi, and the root cells of macrophytes as well as omnivorous and predatory species (Yeates et al, 1993;Traunspurger, 1997). Nematodes are therefore involved in major food web interactions, influencing bacterial and algal communities Traunspurger et al, 1997), competing with other benthic groups for resources (Galassi et al, 2002;Nelson & McInnes, 2002;, and serving as prey for other meiofaunal organisms (Schmid & Schmid-Araya, 2002;Beier et al 2004;Hohberg & Traunspurger, 2005;Muschiol et al, 2008). While a few studies have provided essential information about the seasonal patterns, bathymetric distributions, and energetic aspects of nematodes (Strayer & Likens, 1986;Traunspurger, 1996Traunspurger, , 1997Bergtold & Traunspurger, 2004, 2005a, there is a lack of information on the links between nematode community structure and lake trophic state.…”

Food choice of two bacteria-feeding nematode species dependent on food source, food density and interspecific competition

“…In terms of their food preferences, nematodes comprise generalist as well as specialist species and play a major functional role in the food web due to their consumption of biofilms (Traunspurger, 1997(Traunspurger, , 2000Majdi et al, 2011), whilst in turn serving as food for higher trophic levels, including copepods, macrobenthos and young fish (Schmid-Araya & Schmid, 2000;Beier et al, 2004;Muschiol et al, 2008;Spieth et al, 2011). Nematodes show great diversity in food and feeding habits; they may be monophagous or polyphagous and are able to obtain nutrients from bacteria, algae, diatoms, protozoa, fungi or plant and animal tissues, or even benefit from dissolved organic matter (Moens et al, 1999aHöss et al, 2001;Gaugier & Bilgrami, 2004).…”

“…(Rhabditidae). These two bacterivorous nematodes coexist in a highly homogeneous and stable environment, compete for the same food resources, and play a major role in the cave's food web (Riess et ai, 1999;Muschiol & Traunspurger, 2007;Muschiol et al, 2008). Both nematode species are members of a highly specialised meiofaunal community inhabiting floating chemoautotrophic microbial mats in an isolated groundwater ecosystem (Muschiol, 2009;Schroeder et ai, 2010).…”

4. Ecology of Freshwater Nematodes

“…4.9 . Conversely, the high consumption of nematodes by tardigrades, crustaceans, planarians, nematodes and young fishes was recorded in laboratory experiments (Prejs 1993, Beier et al 2004, Muschiol et al 2008, Hohberg & Traunspurger 2009, Spieth et al 2011 Flagellates and ciliates are both found as food and as competitors for bacteria as a food source .…”