Different life-histories of native and invasiveNeogobius melanostomusand the possible role of phenotypic plasticity in the species’ invasion success

Abstract

Key-words:round goby, biological invasions, epigenesis, alternative ontogenies, reproductive parametersOne of the most successful invasive fish species with negative impacts is round goby Neogobius melanostomus that has spread from its original Ponto-Caspian area to west and central Europe and even to North America. Previous studies focused on invasive fishes have revealed that these species have the capability to generate forms with life-history traits that differ between native and non-native populations. As a contribution to explain their invasion success, the theory of alternative ontogenies and invasive potential has been developed. The main aim of the present study was to test the hypothesis derived from this theory, which predicts that females of the non-native population of N. melanostomus (from Slovakia) will have significantly smaller oocytes, higher fecundity and smaller body size at maturity than those of the native population (from Bulgaria). All the three quantitative parameters of life-history traits examined in this study were found to be consistent with the predictions tested. Variations in reproductive parameters observed in non-native N. melanostomus demonstrate the species' phenotypic plasticity, which appears to be an important attribute that helps potential invaders to establish new populations in unknown environments. However, further experimental studies are necessary to verify this theory by testing hypotheses derived from it. Une des espèces les plus envahissantes de poissons aux impacts négatifs est le gobie à taches noires Neogobius melanostomus qui s'est propagé à partir de sa zone ponto-caspienne native vers l'ouest et le centre de l'Europe et même en Amérique du Nord. Des études antérieures sur les poissons invasifs ont révélé que ces espèces ont la capacité de générer des individus avec des traits d'histoire de vie qui diffèrent entre les populations autochtones et non autochtones. En guise de contribution à expliquer leur succès d'invasion, la théorie des ontogenèses alternatives et du potentiel invasif a été développée. L'objectif principal de cette étude était de tester l'hypothèse dérivée de cette théorie, qui prédit que les femelles de la population non autochtone de N. melanostomus (de Slovaquie) auront de plus petits ovocytes, une plus forte fécondité et une plus petite taille à maturité que celles de la population autochtone (de Bulgarie). Tous les trois paramètres quantitatifs des traits d'histoire de vie examinés dans cette étude ont été jugés conformes aux prédictions testées. Les variations dans les paramètres de reproduction observés chez N. melanostomus non indigènes démontrent la plasticité phénotypique de l'espèce, qui semble être un attribut important qui aide les envahisseurs potentiels à établir de nouvelles populations dans des environnements inconnus. Toutefois, d'autres études expérimentales sont nécessaires pour vérifier cette théorie en testant des hypothèses qui en découlent. RÉSUMÉ

Upstream expansion of round goby (Neogobius Melanostomus) – first record in the upper reaches of the Elbe river

“…It was even introduced and is widely established in the Laurentian Great Lakes (Charlebois et al, 2001;Vanderploeg et al, 2002). Round goby can affect freshwaters as well as brackish ecosystems by its high invasive potential, including high reproductive effort, aggressiveness, high foraging activity and, among others, its role as a vector of parasites (Hempel and Thiel, 2015;Horkova and Kovac, 2014;Ondrackova et al, 2015;Vanderploeg et al, 2002). On the other hand, round goby can represent a significant part of the diet of other fish (Hensler et al, 2008;Vanderploeg et al, 2002).…”

“…As mentioned above, further expansion of round goby has been expected, because of its history of invasion not only in European water systems but also its introduction, establishment and expansion in North America (Czugala and Wozniczka, 2010;Horkova and Kovac, 2014;Pettitt-Wade et al, 2015;Roche et al, 2013). Several ways have been outlined as a possible source of newly detected round goby population in Elbe river: (1) upstream migration from the coastal part of the Elbe River (Hempel and Thiel, 2013); (2) migration through the canals connecting Elbe and Oder Rivers (through the system of canals of the Spree and Havel Rivers) which were also successfully invaded (Grabowska et al, 2010); (3) transport in ballast waters used in shipping; (4) unintentional transport by anglers using round goby as a bait; (5) unintentional introduction by fishermen or aquarists; and (6) transport of juvenile fish or fertilized eggs by other organisms e.g.…”

What can morphology tell us about ecology of four invasive goby species?

“…Neogobius melanostomus appears to have the least specialized external morphology that may favour its invasive success: little specialization to habitat or diet means reduced restraints concerning overall ecological requirements. Of course, flexible life‐history traits (Ľavrinčíková & Kováč, ; Hôrková & Kováč, , ) also contribute essentially to the fact that N. melanostomus is the most successful among the four invaders. The other three species possess some morphological specializations ( P. kessleri to large prey, N. fluviatilis to sandy habitats and P. gymnotrachelus to macrophytes) and none of these gobies have managed to colonize such large areas or reach such overall abundances as N. melanostomus .…”

“…The expansion of these species has probably been facilitated by human activities (freight vessels) (Wiesner, ) and introduction to non‐native regions has happened multiple times (Taraborelli et al ., ; Brownscombe et al ., ). Nevertheless, phenotypic plasticity and flexibility in life‐history traits also contribute to their invasive success, providing them opportunity to adapt easily to different environmental conditions throughout all stages of the invasive process (Kováč et al ., ; Brandner et al ., ; Hôrková & Kováč, , ).…”

First information on age and growth ofPadogobius bonelli(Bonaparte, 1846) outside of its native range: River Aggia (Central Italy)

“…P. bonelli is counted as one of the main threats to the survival of the congeneric P. nigricans, a species endemic to Central Italy, due to: aggressive behaviour and competition for premium reproductive territory (Gandolfi et al 1991;Zerunian, 2004;Mecatti et al, 2010), competition for feeding resources and a higher allocation of energy in reproduction compared to P. nigricans Pompei et al, in press.). A full understanding of life history characteristics of alien species is crucial to assess their possible ecological impact on ecosystems, to predict their invasive potential (Ricciardi and Rasmussen, 1998;Guo et al, 2013;Grabowska et al, 2011;Hôrková and Kováè, 2013) and propose effective management strategies (Guo et al, 2013;Yeates et al, 2012;Giannetto et al, 2014). Although the severe ecological impact of P. bonelli on native species is wide known, to date, any study on age and growth of non-native populations of P. bonelli out of its native range has ever been conducted and basic information on the reproductive biology of this species outside of its native range is only recently available (Pompei et al, in press).…”