Variable effects of an invasive species on the reproduction and distribution of native species in pond networks

Abstract

The arrival of non‐native species in a community can be deleterious for native species. The joint investigation of several descriptors of native populations susceptible to invaders, under different invasion contexts, may help in predicting the outcome of their co‐occurrence with invasive species. Moreover, empirical studies seldom document the relative importance of the effects of invasive species on native species compared with other factors. Using survey data, we evaluated whether reproduction (larval density) and distribution of breeding sites of three amphibian species (Rana dalmatina, Lissotriton helveticus, and Triturus marmoratus) were related to the presence of invasive red swamp crayfish Procambarus clarkii, compared to other native predators, habitat, and landscape features, in two pond networks that differed in invasion intensity. The red swamp crayfish was only negatively associated with the larval density of one amphibian species studied. Its effect size was similar to that of some native predators, and much smaller than that of the canopy cover of ponds. Amphibians were widespread in the two pond networks. The occupancy of only one species in each network was negatively related to crayfish presence, while the occupancy of all species was negatively related to fish presence. The distribution of amphibian breeding sites was positively associated with aquatic vegetation cover. Negative associations between amphibians and red swamp crayfish were detected only in a few cases, even in the most invaded area, and thus results were less alarming than in previous studies. Differences in ecological traits of native amphibians and interactions with other environmental factors may explain the variable effects of red swamp crayfish on native amphibian populations.

A new species ofPseudoacanthocephalus(Acanthocephala: Echinorhynchidae) from the guttural toad,Sclerophrys gutturalis(Bufonidae), introduced into Mauritius, with comments on the implications of the introductions of toads and their parasites into the UK

“…The problem of the effects of non-native, sometimes invasive species in contributing to the current global biodiversity crisis is increasingly recognized (e.g. Jardine & Sanchirico, 2018; Bélouard et al ., 2019). For example, the American bullfrog, Lithobates catesbianus Shaw 1802, has been deliberately or inadvertently released on several continents and in many countries (including the UK) and frequently persists extremely well, acting as an invasive predator, competitor and vector of diseases (Cunningham, 2018; Urbina et al ., 2018).…”

Supplementary material 1 from: Belouard N, Petit EJ, Cucherousset J, Paillisson J-M (2024) Variation of the stable isotope niches of native amphibians in ponds invaded by the red swamp crayfish. NeoBiota 93: 245-262. https://doi.org/10.3897/neobiota.93.120477

“…The present study focused on tadpoles of agile frogs, tadpoles of European tree frogs, adult palmate newts and adult marbled newts in a large network of ponds in the Regional Natural Park of Brière (northwest France, ~ 15 ponds/km 2 , see Belouard et al (2019a) for a detailed description of the study area). In ponds, herbivorous-omnivorous tadpoles develop from March to June and adult predatory newts are present from January-March to June-July (Montaña et al 2019;Sánchez-Hernández 2020).…”

“…Therefore, a limited fraction of ponds was appropriate to obtain enough specimens for SIA. The selection of 18 ponds was not intended to be representative of the co-existence rates between species, a topic addressed elsewhere (Belouard et al 2019a). The ponds under study include natu- ral variation in amphibian and crayfish abundances and environmental conditions across the study area (see subsection -Sample collection and Table 1).…”

Similar species, different fates: Abundance dynamics in spatially structured populations of common and threatened frogs

“…The red swamp crayfish has a great potential to negatively affect frog populations: it has a generalist diet, can feed on tadpoles and egg masses, and can modify habitats through the consumption of macrophytes and burrowing (Cruz et al, 2006;Lo Parrino et al, 2020). Previous analyses on the presence/absence of R. dalmatina revealed no site-level effect of invasive crayfish (Bélouard et al, 2019;Falaschi et al, 2021). Still, our results indicate lower abundance in wetlands occupied by this invasive species (Figure 3c), even if the crayfish was only found in a few sites (max.…”