Rapid response of invasive round goby (Neogobius melanostomus) (Pallas, 1814) to an environmental perturbation demonstrated in reproductive parameters of females

Plasticity in life-history traits appears to be very important for adaptation of invasive species to a novel environment. Predictable changes in life-history traits have been observed in the progression of invasions in several fish species. Nevertheless, the novel environment of the invaded areas can pose a challenge to the invaders caused by sudden perturbations in the ecological conditions. The aim of this study was to examine whether a sudden environmental disruption would reflect in significant changes in the reproductive parameters of the females of an invasive round goby (Neogobius melanostomus) population. Samples were collected from the middle section of the River Danube (Bratislava, Slovakia) from the 2008 post-spawning period to the end of spawning in 2010. The results support the prediction that after a strong environmental perturbation, the females increase their absolute as well as relative numbers of oocytes and their real absolute fecundity; the differences in all of these parameters were statistically significant. Another strong environmental disruption occurred in June 2010, although the response differed from that of 2009. In 2009, the females responded by increasing their oocyte numbers; in 2010, they extended their reproductive season by producing an extra batch of eggs. This can be explained by the different timing of the sudden perturbations. In summation, a coincidence between the environmental perturbations and the significant changes in their reproductive traits was found in the round goby females in the two subsequent years. This indicates that the round goby can respond rapidly to environmental disruptions, and that such reproductive flexibility likely helps the species in its successful invasions.