Niche differentiation between sympatric alien aquatic crustaceans: An isotopic evidence

Abstract

Among the mechanisms that allow competing species to coexist are resource partitioning and dietary segregation. The current study uses multiple stable isotopes, carbon (␦ 13 C), nitrogen (␦ 15 N) and sulphur (␦ 34 S), to test the hypothesis that dietary segregation in cohabiting invasive mysids (Limnomysis benedeni and Katamysis warpachowskyi) and gammarids (Dikerogammarus villosus and Gammarus roeselii) will be reflected by differences in isotope values. Furthermore, IsoError mixing models were used to estimate the relative contributions of periphyton and seston to the invaders' diets. Whole tissue ␦ 13 C, ␦ 15 N and ␦ 34 S analysis in L. benedeni and K. warpachowskyi imply that these sympatric, non-native mysids maintain differentiated feeding niches or resource partitioning by feeding on distinct components of the available food resources (predominantly seston by L. benedeni and periphyton by K. warpachowskyi). By contrast, the gammarids D. villosus ('killer shrimp') and G. roeselii exhibited no significant difference in ␦ 13 C and ␦ 15 N, indicating a considerable overlap between the dietary sources of these sympatric invaders. Feeding niche differentiation, irrespective of season or the nature of habitat invaded (lake or river), might facilitate the coexistence of invasive mysids in their 'new' environment by minimizing direct resource competition. The mutual interaction by the invasive gammarids, coupled with voracious behavior, could assist their success at co-invasion with serious implications for local biodiversity including the potential extinction of native species.

Dietary niche divergence between two invasive fish in Mediterranean streams

“…However, empirical investigations on the mechanisms that may facilitate coexistence of invader species with similar trophic niches remains scarce (but see Jackson and Britton, 2014). Moreover, evidence for species coexisting with similar trophic niche is controversial, with some studies indicating that sympatric species exhibit narrower dietary niches than their allopatric conspecifics (Bolnick et al, 2010;Jackson et al, 2012) and display broader niches when resources are abundant (Jackson and Britton, 2014;Rothhaupt et al, 2014), whereas other studies show that the dietary niche of sympatric species converge (Cucherousset et al, 2007;Gabler and Amundsen, 2010). Closer examination of the interplays between dietary niche, niche width and overlap among invaders in allopatric and sympatric situations is thus critical to clarify mechanisms allowing invasive species coexistence.…”

Feeding behaviour, predatory functional responses and trophic interactions of the invasive Chinese mitten crab (Eriocheir sinensis) and signal crayfish (Pacifastacus leniusculus)

“…Due to the often complex nature of freshwater food webs, with high connectance (Polis & Strong, ; Woodward et al ., ), predation by invaders at one trophic level can cause cascading effects. Further, where invaders that exploit similar food resources occur in sympatry, they may switch prey or broaden their resource base (Jackson & Britton, ; Rothhaupt, Hanselmann & Yohannes, ), resulting in increased predatory pressure on these alternative prey species. To disentangle the effects of multiple invaders in an ecosystem, it is necessary to quantify impacts (e.g.…”

The Ponto-Caspian mysid Paramysis lacustris (Czerniavsky, 1882) has colonized the Middle Danube

“…The species also serves as an important food source for fish; however, long-term positive effects on fish production have not been proved (Arbačiauskas et al, 2010). Considerable negative consequences on the other mysids cannot be expected, since their habitat preferences (Borza et al, 2017) as well as their diets (Rothhaupt et al, 2014) are markedly different.…”