Aquatic Invasions (2018) Volume 13, Issue 4: 553–563 DOI: https://doi.org/10.3391/ai.2018.13.4.12 © 2018 The Author(s). Journal compilation © 2018 REABIC This paper is published under terms of the Creative Commons Attribution License (Attribution 4.0 International - CC BY 4.0) Special Issue: Biological Invasions in Inland Waters Research Article Non-lethal effects of a native and a non-native piscivorous fish on the interaction between a mesopredator and benthic and pelagic invertebrates Bruno R. S. Figueiredo1,*; Leandro F. Fiori1; Friedrich W. Keppeler2; Roger P. Mormul1 and Evanilde Benedito1 1Programa de Pós-Graduação em Ecologia de Ambientes Aquáticos Continentais, Núcleo de Pesquisas em Limnologia, Ictiologia e Aquicultura (Nupélia), Universidade Estadual de Maringá (UEM), Avenida Colombo, 5790, Bloco H-90, Maringá, PR, CEP 87020-900, Brazil 2Department of Wildlife and Fisheries Sciences, Texas A&M University, 645 Lamar St, Heep 112, College Station, TX 77843-2358, USA Author e-mails: [email protected] (BRSF), [email protected] (LFF), [email protected] (FWK), [email protected] (RPM), [email protected] (EB) *Corresponding author Received: 27 April 2018 / Accepted: 14 October 2018 / Published online: 12 November 2018 Handling editor: Amy Deacon Abstract Predator presence may result in non-lethal costs to prey; these costs may be even larger if both predators and prey do not naturally co-occur. We experimentally evaluated the survival of two aquatic invertebrates from the upper Paraná River basin (Chironomus sancticaroli – benthic and Daphnia magna – pelagic) exposed to a native mesopredator fish (Astyanax lacustris) in three non-lethal predation treatments: (i) the absence of piscivorous fish, (ii) the presence of a native piscivorous fish (Hoplias aff. malabaricus), or (iii) the presence of a non-native piscivorous fish (Astronotus crassipinnis). The treatments were crossed with the absence and presence of vegetated habitats. We predicted that the mesopredator might not have adapted foraging strategies to eat in the presence of an unfamiliar predator while invertebrate prey use vegetated habitats for protection. Therefore, we expected that the combination of piscivorous fish presence and vegetated habitat would lead to a classical additive response on invertebrate survival, which will be higher in the presence of non-native piscivorous fish than in the presence of native piscivorous fish. The presence of vegetated habitat and piscivorous fish increased invertebrate survival, but together they did not promote an additive response. Instead, the non-lethal cascade effects of the native piscivorous fish was similar between vegetation treatments, whereas the non-native piscivorous fish led to higher survival of the invertebrates in non-vegetated versus vegetated habitats. Although refuges are understood as elements that enhance predator-prey stability, the effectiveness of submerged macrophyte stands as safe habitats is dependent on some predator traits, such as origin and hunting mode. Our results also indicate that the invasion of A. crassipinnis has the potential to change mesopredator prey selectivity from a diet based on pelagic prey with the native H. aff. malabaricus to the random consumption of pelagic and benthic prey, which may have important consequences for the stability of natural aquatic food webs. Key words: anti-predator behaviour, evolutionary history, predation threat, predator-prey interaction Introduction the abundance of aquatic invertebrates (Carpenter et al. 1985). Although there is empirical evidence for The presence or absence of predators may lead to this traditional theoretical model (e.g., Benndorf et profound changes in trophic links and in the survival al. 2002), one of its main limitations is the consi- of species of a lower trophic level (Carpenter et al. deration of only the lethal effects of predators. The 1985; Pace et al. 1999; Estes et al. 2011). According simple presence of a predator may also provide a to cascade models of aquatic food webs, an increase non-lethal cost to prey, which often spends more in piscivorous biomass reduces both zooplanktivorous time in a vigilant state after perceiving the predation and benthivorous fish biomass, which in turn increases threat (Lima 1998; Werner and Peacor 2006; Ajemian 553 B.R.S. Figueiredo et al. et al. 2015). When prey display anti-predation beha- (Peretti and Andrian 2008; Montenegro et al. 2013). viours (such as keeping in a vigilant state), they Around the year 2000, an omnivorous predator fish consequently reduce the time spent on feeding- with a high tendency for piscivory, Astronotus related events (Abrahams et al. 2009; Rudman et al. crassipinnis Heckel, 1840 (Perciformes: Cichlidae) 2016), ultimately impacting the prey reproduction (hereafter considered as a piscivorous fish), native to and growth rates (McPeek 2004; Ahlgren et al. 2011). the Amazon River basin, was introduced into the Therefore, the mere presence of predators may be as upper Paraná River by fish-stocking programmes important as their consumption effect on the commu- (Garcia et al. 2018). Astronotus crassipinnis is an nity assemblage (Romare and Hansson 2003). active predator well-adapted to living in shallow Anti-predator behaviours that minimise the costs lakes (Abujanra et al. 2009; Júlio-Júnior et al. 2009). while maximising the benefits usually evolve in Presently, there have been no reports regarding the predator-prey interactions over co-occurrence time extent of environmental alteration caused by A. crassi- between predators and prey species (Abrahams et al. pinnis. However, the effects of A. crassipinnis on 2009; Lazzaro et al. 2009; Sih et al. 2010). The effects native fish populations could be similar to that of of predator presence may be more pronounced when Cichla kelberi Kullander and Ferreira, 2006 (Per- the predator involved is a non-native species given ciformes: Cichlidae), another recent non-native the lack of prey adaptation to avoid being eaten cichlid established in the region. Cichla kelberi was (Salo et al. 2007; Martin 2014). Introduced predators responsible for a 95% decline in native fish density might also be able to decrease prey populations not and an 80% decline in fish richness in a reservoir by a xenophobic effect (Simberloff 2003) but rather located in the upper Paraná River basin (Pelicice and because invaders could present higher resource use Agostinho 2009; Pelicice et al. 2015). efficiency than native species and have superior This relationship between the arrival of a new competitive ability (e.g., Vilà and Weiner 2004; predator and the decline in native fish populations Alexander et al. 2014). Conversely, species with may have occurred because the prey was not high anti-predator plasticity behave cautiously prepared to recognise and avoid such a new threat towards any new threat (Sneddon et al. 2003; (naiveté hypothesis, Cox and Lima 2006), and con- Mesquita and Young 2007); this trait may concede sequently it may have experienced higher rates of them some resistance to predator introduction. mortality compared with a condition without the However, mesopredator species in a constant vigilant exotic predator (Sih et al. 2010). Alternatively, the state usually decrease their foraging area and new top predator may have had few antagonistic consumption rate, benefiting the trophic level below. trophic interactions in the new environment (enemy Mesopredators may also feed on non-preferential release hypothesis, Williamson 1996), which allowed prey types in safe areas to maintain their energy it to have a high population growth rate. Therefore, intake (Persson and Eklöv 1995). Although species A. crassipinnis can be a potential danger to native origin does matter (Paolucci et al. 2013), differences fish populations in lentic environments, as C. kelberi in predator hunting modes might also affect the was. The negative impact caused by A. crassipinnis structure of trophic cascades because they lead to to native fish populations may be further intensified different prey responses (Miller et al. 2014). For in environments with greater water transparency example, the mayfly Baetis bicaudatus Dodds, 1923 (e.g., Figueiredo et al. 2016), such as the current (Insecta: Baetidae) hides under rocks when threatened state of the upper Paraná River basin, generated by by an active predator (trout) but tends to be more the increasing number of hydroelectric reservoirs active and less timorous in the presence of a less (Stevaux et al. 2009). active predator (stoneflies) (Peckarsky and McIntosh Both H. aff. malabaricus and A. crassipinnis 1998). In this sense, the interaction between pisci- inhabit shallow lakes with large littoral areas, where vorous (tertiary consumer) species origin and hunting vegetated habitats, such as macrophyte beds, are mode may elicit more profound changes in prey fish abundant. Vegetated habitats are recognised as behaviour (secondary consumer), which might end up crucial providers of refuge for prey because their affecting the consumption of invertebrates (primary structural complexity can limit the movement of consumer). large predators and reduce the likelihood of encoun- Hoplias aff. malabaricus Bloch, 1794 (Osteich- ters between predators and prey (Diehl 1988; Padial thyes: Erythrinidae) is a native sit-and-wait predator et al. 2009). Thus, the presence of vegetated habitats (Montenegro et al. 2013) of the upper Paraná River might reduce the predation rates of mesopredators floodplain, southern