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Poster De Conférence Année : 2018

Response of anecic individual weight to species interactions (epi-anecic vs strict-anecic)

Résumé

European earthworm species are classified as epigeic, anecic or endogeic due to their ecology, behaviour and physiology (Bouché, 1972, 1977). Within the anecics, studies observed that it was possible to distinguished the epi-anecics feeding on fresh organic matter (OM) and burying OM into the soil profile, from the strict-anecics feeding on older or humified OM (Jégou et al., 1998, 2000; Andriuzzi et al., 2015; Larsen et al., 2016). This distinction means that epi-anecic and strict-anecic feed on two distinct pools of OM and thus should not compete for nutritive resources. However, to our knowledge, no studies focused on the interaction between these two ecological categories, epi-anecic and strict-anecic. In this context, our objectives were to determine the mixing effect by pairing two species (i) within the epi-anecics (ii) within the strict-anecics and (iii) between epi-anecic and strict-anecics, on earthworms’ individual weight. An experiment in controlled conditions was conducted in 5 replicates with (i) monocultures (two individuals) of three epi-anecic species (Lumbricus rubellus, L. centralis and L. terrestris) and three strict-anecic species (Aporrectodea caliginosa meridionalis, A. nocturna and A. giardi) and (ii) paired species in soil mesocosms. The earthworms were initially fed with Lolium perenne at the soil surface and the mesocosms were placed in a climatic chamber at 12 °C, with a relative humidity of 85% and a 12h:12h light:dark regime during 30 days. At the beginning and at the end of the experiment, each individual was weighed after 24 h placed on a moist sponge in a plastic box for depuration. In monoculture modalities, only A. giardi lost weight while L. rubellus and L. terrestris won weight, the others species maintained their initial weight. In modalities with pairs of species within the same ecological category, epi-anecic species won weight compared to the monoculture epi-anecic species whereas strict-anecic mass did not change between monoculture or pair species (no effect of species interaction). In modality with species paired between the two ecological categories, the results are species dependent. Interestingly, A. giardi maintained its initial weight in paired species contrarily to monoculture.
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Dates et versions

hal-02262557 , version 1 (02-08-2019)

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  • HAL Id : hal-02262557 , version 1

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Kevin Hoeffner, Mathieu Santonja, Cécile Monard, Daniel Cluzeau. Response of anecic individual weight to species interactions (epi-anecic vs strict-anecic). 1st International Earthworm Congress, Jun 2018, Shanghaï, China. ⟨hal-02262557⟩
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