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Predation rates and prey selectivity in two predacious estuarine nematodes
Moens, T.; Herman, P.M.J.; Verbeeck, L.; Steyaert, M.; Vincx, M. (2000). Predation rates and prey selectivity in two predacious estuarine nematodes. Mar. Ecol. Prog. Ser. 205: 185-193. dx.doi.org/10.3354/meps205185
In: Marine Ecology Progress Series. Inter-Research: Oldendorf/Luhe. ISSN 0171-8630; e-ISSN 1616-1599
Peer reviewed article  

Available in  Authors 
    Vlaams Instituut voor de Zee: Open access 262730 [ download pdf ]

Keywords
    Environmental effects > Light effects
    Environmental effects > Temperature effects
    Interspecific relationships > Predation
    Interspecific relationships > Predation > Prey selection
    Adoncholaimus fuscus (Bastian, 1865) Filipjev, 1918 [WoRMS]; Enoploides longispiculosus Vitiello, 1967 [WoRMS]; Nematoda [WoRMS]
    ANE, Netherlands, Oosterschelde [Marine Regions]; ANE, Netherlands, Westerschelde [Marine Regions]
    Marine/Coastal
Author keywords
    nematodes; predation; prey selectivity; encounter probability; top-down control

Authors  Top 
  • Moens, T.
  • Herman, P.M.J.
  • Verbeeck, L.
  • Steyaert, M.
  • Vincx, M.

Abstract
    Enoploides longispiculosus and Adoncholaimus fuscus are representatives of nematode genera prominent in sediments of the North Sea and adjacent estuaries. Both are predatory nematodes, although predation is facultative in the latter. The present study investigates functional responses and prey selectivity in both species through the use of controlled laboratory experiments. Both predators had strongly prey density-dependent predation rates. A maximal predation rate of 4 monhysterid prey nematodes per predator per 24 h was found inE. longispiculosus at prey densities of 200 ind. per petri dish and higher; no such maximal predation rate was found for A. fuscus, indicating that this species was prey-limited at all prey densities tested. Predation rates were strongly affected by temperature, with a Q10 close to 2 between 10 and 20 °C. Incubation in the light resulted in a similar decrease in predation rate compared to dark incubations, as did a temperature decrease from 20 to 10 °C. E. longispiculosus exhibited a clear preference for some nematode prey over others. An encounter probability model indicated that preferences could not be explained by encounter rates. Strike rates were low (<10%) in E. longispiculosus, and exceptionally low (<<1%) in A. fuscus, indicating that many encounters did not result in attack, or that a portion of the attacks did not result in prey capture. The observed predation rates cannot be supported by prey nematode standing stock and production at the 2 sampling sites used in this study, where E. longispiculosus dominates the nematode community in abundance and, especially, biomass. A. fuscus may mainly derive food from feeding modes other than predation; E. longispiculosus may be prey-limited in its natural habitat. Since this nematode also feeds on other metazoans, it may also impact temporary meiofauna. The high predation rates and prey selectivity of predacious nematodes may be important structuring factors to meiofaunal communities.

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