Behavioral Interactions and Trophic Overlap between Invasive Signal Crayfish Pacifastacus leniusculus (Decapoda, Astacidae) and Native Fishes in Iberian Rivers

Abstract

The signal crayfish Pacifastacus leniusculus Dana, 1852 is a successful invasive species in the Iberian Peninsula. This is of particular conservation concern, as fish fauna is highly endemic and also threatened within this ecoregion. The aim of this study was to analyze behavioral interactions and trophic overlap between signal crayfish and native fishes in Iberian rivers (northern Spain). Video cameras were used to record fish “dominance/evasion” after spatial encounters with crayfish. Diet composition and isotopic signatures (δ13C and δ15N) were compared to evaluate the niche overlap. Fish were dominant in 25% of the encounters with juvenile crayfish, whereas this percentage was only 4% with adult crayfish. Observations showed a high fish “evasion” response for Pyrenean stone loach Barbatula quignardi (Bǎcescu-Meşter, 1967) (>30%). Dietary results showed a high trophic overlap between signal crayfish with the pelagic Pyrenean minnow Phoxinus bigerri Kottelat, 2007 and the benthic loach. However, the isotopic niche overlap was low, with brown trout Salmo trutta L., 1758 showing the highest area (only 0.1 ‰2). Overall, our findings suggest that interferences may occur with native species for food (i.e., benthic invertebrates). Consequently, measures should be applied to control invasive crayfish in Iberian rivers.

Molecular Epidemiology, Virulence Traits and Antimicrobial Resistance Signatures of Aeromonas spp. in the Critically Endangered Iberochondrostoma lusitanicum Follow Geographical and Seasonal Patterns

“…Interestingly, although I. lusitanicum suggested prey items, such as macroinvertebrates and zooplankton, are available in the dry season [40,41], their diversity and abundance decrease in streams highly impacted by pollution and hydric stress [42,43]. This situation likely generates intra-specific and interspecific competition for food, particularly with invasive species that are better adapted to environmental critical conditions [44,45]. It is also likely that, as observed for other species, I. lusitanicum individuals would change their dietary focus into plant material and detritus under critical conditions [46].…”

Unprepared to Deal with Invasion: Pre-Service Teachers’ Perception, Knowledge and Attitudes toward Invasive Species

“…In contrast, there is a greater social rejection of other types of organisms, mainly invertebrates [68], which could favor greater support for the sacrifice of invasive taxa of this type, according to the present study in relation to the signal crab. However, the percentage of students who would not carry out any action to eliminate this crab from the colonized ecosystems was very high (40%), despite the significant impacts that it generates in the study area [9,69], and unlike the 84% of the students who supported the American mink's control, although rejecting its sacrifice. The greater resources devoted to conservation of mammals such as the European mink seem to encourage citizens to support the control of other invasive mammal species that reduce their populations.…”

“…Regarding the lack of awareness of the involuntary transport on personal objects, pre-service teachers seemed not to be aware of their own role as potential IAS vectors. This unawareness was especially relevant in the case of the fluvial ecosystems of the study area, where there are many microscopic IAS or species with microscopic phases in their life cycle that generate important ecological and economic impacts, such as the IAS used as examples in this study (i.e., the signal crab [9]) or other relevant species like the zebra mussel [56] or Didymosphenia geminata [57]. Dispersal of these species and others is involuntarily carried out by citizens in their various forms of contact with rivers [58].…”

“…The effects on biodiversity caused by these species are so intense that they are leading to a process of biotic homogenization of the Earth's surface [6,7]. In the north of the Iberian Peninsula, where the present study was carried out, there are many examples of IAS outcompeting local endangered species, highlighting the American mink (Neovison vison) severely affecting the European mink (Mustela lutreola) [8], or the signal crab (Pacifastacus leniusculus) partly responsible for the recent extirpation of the white-clawed crab (Austropotamobius pallipes) in many streams [9]. However, the generated impacts go further, with important human well-being and socioeconomic effects [10], fundamentally concerning agriculture, forestry, energy and health sectors, generating associated costs for their control and eradication, and reducing ecosystem services [2,11].…”

The life-history of a late Mesolithic woman in Iberia: A sequential multi-isotope approach

“…That both taxa analyzed show similar δ 13 C values (trout: x ̅ = -21.6 ± 0.1‰; barbel: x ̅ = -21.9 ± 1.0‰) is consistent with both species living in the same aquatic ecosystem. This would have probably been the Irati river, as suggested not only by its proximity to the site, but also by measurements made on the flesh of modern trout from the same and nearby rivers (Vedia et al, 2019) which, adjusted by ca. +2.9 ±1.0‰ for the expected flesh to bone collagen tissue fractionation (Robson et al, 2012), and by another +1.5‰ for the world-wide decrease in atmospheric 13 C caused by the burning of fossil fuels (the Suess effect) (Keeling, 1979), provide similar values (x ̅ = -22.2 ± 2.3‰).…”