Some like it hot: factors impacting thermal preferences of two Ponto-Caspian amphipodsDikerogammarus villosus(Sovinsky, 1894) andDikerogammarus haemobaphes(Eichwald, 1841)

Abstract

Temperature is a crucial factor determining biology and ecology of poikilothermic animals. It often constitutes an important barrier for invasive species originating from different climate zones but, on the other hand, may facilitate the invasion process of animals with wide thermal preferences and high resistance to extreme temperatures. In our experimental study, we investigated the thermal behaviour of two Ponto-Caspian amphipod crustaceans—Dikerogammarus villosus and Dikerogammarus haemobaphes. Both species are known to live under a wide range of thermal conditions which may promote their invasion. Moreover, both these amphipods are hosts for microsporidian parasites which co-evolved with them within the Ponto-Caspian region and spread in European waters. As the presence of a parasite may influence the thermal preferences of its host, we expected to observe behavioural changes in infected individuals of the studied amphipods leading to (1) behavioural fever (selecting a warmer habitat) or (2) anapyrexia (selecting a colder habitat). The experiment (N = 20) was carried out for 30 min in a 100 cm. 20 cm from boths sides were not avaliable for amphipods long thermal gradient (0–40 °C), using 30 randomly selected adult amphipod individuals of one species. At the end of each trial, we checked the position of amphipods along the gradient and determined their sex and infection status (uninfected or infected by one of microsporidium species). D. villosus was infected with Cucumispora dikerogammari whereas D. haemobaphes was a host for C. dikerogammari, Dictyocoela muelleri or D. berillonum. Thermal preferences of amphipods depended on their species and sex. Females of D. villosus preferred warmer microhabitats (often much above 30 °C) than conspecific males and females of D. haemobaphes, whereas no significant differences were found among males of both species and both sexes of D. haemobaphes. Moreover, infected males of D. villosus stayed in warmer water more often than uninfected males of this species, selecting temperatures higher than 30 °C, which may be explained either as a behavioural fever constituting a defence mechanism of a host against the infection, or as a parasite manipulation of the host behaviour increasing the parasite fitness. On the other hand, none of the parasite species affected the thermal preferences of D. haemobaphes, including also C. dikerogammari, changing the behaviour of D. villosus. Our research presents the complexity of the thermal behaviour of studied amphipods and the evidence that microsporidia may trigger a change in temperature preferendum of their host species and those observations may be the result of different host-parasite coevolution time which may vary for the two host species (Poulin, 2010).

Movement of Southern European Aquatic Alien Invertebrate Species to the North and South

“…Unfortunately, these species are generalists [65][66][67][68]-they utilise different food sources and have relatively wide thermal tolerance [69,70]. Some of these are tending to decline, compete, and displace native species from their habitats [71][72][73] and to re-engineer the new ecosystems [74]. Further changes in the distribution of Southern European aquatic alien invertebrate species are expected due to climate change and the degradation of habitats in their native areas.…”

Effects of temperature and a manipulative parasite on the swimming behaviour of Gammarus pulex in flowing water

“…According to Foucreau et al (2014), G. pulex have a reduced lifespan above 21°C. We also know that thermal optimum differs among gammarids species and sex (Rachalewski et al, 2018), and there is local adaptation by different populations of G. pulex living in contrasting thermal conditions (Foucreau et al, 2016).…”

“…Temperature is a key environmental factor affecting both the physiology and the behaviour of freshwater organisms (Sainte-Marie, 1991;Foucreau et al, 2014;Kobak et al, 2017;Rachalewski et al, 2018), including associated parasites (Marcogliese, 2001). could alter the behaviour and the ecology of a freeliving freshwater species and its associated parasite.…”

What doesn’t kill you doesn’t make you stronger: Parasites modify interference competition between two invasive amphipods

“…Parasite-induced changes are usually multidimensional, altering multiple phenotypic traits by a single parasite (Cezilly and Perrot-Minnot 2010;Cezilly et al 2013). This includes such aspects as morphology (Bakker et al 1997), habitat selection (Żbikowska and Cichy 2012;Rachalewski et al 2018), mobility (Dezfuli et al 2003), boldness (Flegr 2015), aggression (Thomas et al 2005;Mikheev et al 2010), foraging (Fielding et al 2003;Bącela-Spychalska et al 2014) and reproduction (Hall et al 2007). These changes may further propagate to the impact on ecosystem functioning (Friesen et al 2017;Anaya-Rojas et al 2019) through intra-and interspecific interactions of infected individuals with other organisms through consumption (Fielding et al 2003), predation (Bakker et al 1997;Flegr 2015;Friesen et al 2019) or competition (Anderson and May 1986;Mikheev et al 2010;Reisinger et al 2015;Friesen et al 2018).…”

“…Some of them can affect their host's behaviour, such as activity and predation (Bacela-Spychalska et al 2014;Farahani et al 2021). The strength of parasite impact depends on the transmission mode: horizontal, vertical or both (Dunn et al 2001;Bącela-Spychalska et al 2014;Bojko et al 2018;Rachalewski et al 2018). In general, the horizontal transmission is often linked to high virulence (Fielding et al 2005), while vertical transmission is associated with low or no virulence, or even with the increased host fitness (e.g.…”