Invasion strategies in round goby (Neogobius melanostomus): Is bigger really better?

Abstract

Few studies have systematically investigated mid- or long-term temporal changes of biological characteristics in invasive alien species considering the different phases of an invasion. We studied the invasion performance of one of the most invasive species worldwide, the round goby Neogobius melanostomus, from total absence over first occurrence until establishment from 2010 to 2015 in the upper Danube River. After an upstream movement of the invasion front of about 30 river km within four years, the pattern that round goby pioneering populations significantly differ from longer established ones has been confirmed: Pioneering populations at the invasion front comprised more females than males, and adult specimens with a larger body size compared to those at longer inhabited areas. On the population-level, the proportion of juveniles increased with time since invasion. The results of this study provide support for the previously postulated ´bigger is better´ and ´individual trait utility´ hypotheses explaining invasion success in round goby. Pioneering invaders with their greater exploratory behavior, highly adaptive phenotypic plasticity and increased competitive ability seem to act as prime emperors of new habitats, strongly following and benefiting from man-made river-bank structures.

Morphological and molecular data show no evidence of the proposed replacement of endemic Pomphorhynchus tereticollis by invasive P. laevis in salmonids in southern Germany

“…Indeed, Hohenadler et al [15] has shown that P. laevis is in the process of replacing the endemic P. tereticollis in eels captured from the High Rhine. However, the gobies did not passed the Rhine Falls to reach the Bodensee area and have also not spread into the river Danube in Baden-Württemberg [37,52]. This is consistent with the front of the expansion of P. laevis over the Danube not reaching Austria yet in 2006 [18] and our finding that Graylings from the Danube River being infected with P. tereticollis rather than P. laevis.…”

Functional feeding traits as predictors of invasive success of alien freshwater fish species using a food-fish model

“…In N . melanostomus it was found that individuals at the invasion front were different from those in longer established areas, mostly in traits related to size, growth, and feeding (the “bigger is better” hypothesis), increasing their competitive capability [ 57 , 58 ]. Therefore incorporating intra-specific variation in ecomorphological analyses to assess invasion risk is highly recommended.…”

Invasive round goby Neogobius melanostomus has sex‐dependent locomotor activity and is under‐represented in catches from passive fishing gear compared with seine catches

“…The higher activity of males can be a reason why there is a higher proportion of males in some newly invaded sites (Azour et al ., ; Gutowsky & Fox, ). On the other hand, some studies observed the opposite sex ratios at invasion fronts (Brandner et al ., a, ; Gutowsky & Fox, ). Such discrepancy could be related to population‐specific reactions to various ecological conditions or different sampling methods.…”

“…The higher activity of males can be a reason why there is a higher proportion of males in some newly invaded sites (Azour et al, 2015;Gutowsky & Fox, 2011). On the other hand, some studies observed the opposite sex ratios at invasion fronts (Brandner et al, 2013a(Brandner et al, , 2018Gutowsky & Fox, 2012).…”