03050nas a2200313   4500008004100000022001400041245010100055210006900156260001300225300001100238490000700249520216500256653001202421653001202433653001702445653001502462653002302477653002302500653001502523653001702538653002302555653001202578653001102590100001702601700002102618700002502639700002002664856005202684       2014                        eng d  a1365-265600aPredator effects on a detritus-based food web are primarily mediated by non-trophic interactions0 aPredator effects on a detritusbased food web are primarily media  c2014 Jul  a953-620 v833 a<p>Predator effects on ecosystems can extend far beyond their prey and are often not solely lethally transmitted. Change in prey traits in response to predation risk can have important repercussions on community assembly and key ecosystem processes (i.e. trait-mediated indirect effects). In addition, some predators themselves alter habitat structure or nutrient cycling through ecological engineering effects. Tracking these non-trophic pathways is thus an important, yet challenging task to gain a better grasp of the functional role of predators. Multiple lines of evidence suggest that, in detritus-based food webs, non-trophic interactions may prevail over purely trophic interactions in determining predator effects on plant litter decomposition. This hypothesis was tested in a headwater stream by modulating the density of a flatworm predator (Polycelis felina) in enclosures containing oak (Quercus robur) leaf litter exposed to natural colonization by small invertebrates and microbial decomposers. Causal path modelling was used to infer how predator effects propagated through the food web. Flatworms accelerated litter decomposition through positive effects on microbial decomposers. The biomass of prey and non-prey invertebrates was not negatively affected by flatworms, suggesting that net predator effect on litter decomposition was primarily determined by non-trophic interactions. Flatworms enhanced the deposition and retention of fine sediments on leaf surface, thereby improving leaf colonization by invertebrates - most of which having strong affinities with interstitial habitats. This predator-induced improvement of habitat availability was attributed to the sticky nature of the mucus that flatworms secrete in copious amount while foraging. Results of path analyses further indicated that this bottom-up ecological engineering effect was as powerful as the top-down effect on invertebrate prey. Our findings suggest that predators have the potential to affect substantially carbon flow and nutrient cycling in detritus-based ecosystems and that this impact cannot be fully appreciated without considering non-trophic effects.</p>
10aAnimals10aBiomass10aCarbon Cycle10aFood Chain10aGeologic Sediments10aModels, Biological10aplanarians10aPlant Leaves10aPredatory Behavior10aQuercus10aRivers1 aMajdi, Nabil1 aBoiché, Anatole1 aTraunspurger, Walter1 aLecerf, Antoine  uhttps://continenticola.myspecies.info/node/172301830nas a2200253   4500008004100000022001400041245007000055210006900125260001300194300000900207490000700216520113500223653001401358653001201372653001901384653001301403653001501416653001101431653001001442653003101452100001901483700002201502856005201524       2006                        eng d  a1520-408100aToxicity of nitrite to three species of freshwater invertebrates.0 aToxicity of nitrite to three species of freshwater invertebrates  c2006 Feb  a90-40 v213 a<p>Nitrite is a compound with a high toxicity to aquatic animals. Several anthropogenic pollution sources are increasing the concentrations of this component of the nitrogen cycle. Despite this toxicity, there is little available literature on its effects on freshwater invertebrates. Laboratory bioassays were performed to obtain data on the lethal effects of nitrite to three species of freshwater invertebrates: the planarian Polycelis felina and the amphipods Echinogammarus echinosetosus and Eulimnogammarus toletanus. The LC(50), LC(10), and LC(0.01) values (mg/L NO(2)--N) at 24, 48, 72, and 96 h were calculated for each species. E. toletanus and E. echinosetosus were the most sensitive species, with 96 h LC(50) values of 2.09 and 2.59 mg/L NO(2)--N, respectively. In contrast, the planarian P. felina showed a higher tolerance to nitrite, with a 96 h LC(50) value of 60.0 mg/L NO(2)--N. The obtained results were compared with the reported nitrite data for other freshwater invertebrates. This study may contribute to a more appropriate assessment of the ecological risk of this compound in freshwater ecosystems.</p>
10aAmphipoda10aAnimals10aLethal Dose 5010aNitrites10aplanarians10aRivers10aSpain10aWater Pollutants, Chemical1 aAlonso, Alvaro1 aCamargo, Julio, A  uhttps://continenticola.myspecies.info/node/1718