The Invasive Round Goby Neogobius melanostomus as a Potential Threat to Native Crayfish Populations

Abstract

Despite the spread of round goby Neogobius melanostomus into freshwater streams, there is a lack of information with respect to its effect on macroinvertebrate communities, especially crustaceans. We studied foraging efficiency of N. melanostomus on Procambarus virginalis and Asellus aquaticus, using a functional response (FR) approach. Stocking density of the prey species was manipulated to determine its effect on consumer utilization, with prey offered separately or combined at 1:1, 3:1, and 1:3 at each tested density. For both prey species, N. melanostomus exhibited type II FR, occasionally with a high proportion of non-consumptive mortality. Procambarus virginalis suffered a significantly higher attack rate compared to A. aquaticus. Neogobius melanostomus killed significantly more of the most prevalent prey, regardless of species. In trials with prey species of equal proportions, a difference in the number of each species killed was observed only at the highest density, at which P. virginalis was preferred. Neogobius melanostomus may be an important driver of population dynamics of prey species in the wild. The non-selective prey consumption makes N. melanostomus a potential threat to macrozoobenthic communities of river tributaries.

Feeding in predator naïve crayfish is influenced by cues from a fish predator

“…Interactions between crayfish and fish, including competition for shelter, direct predation and behavioural alterations have previously been described 54 . Crayfish are a known prey item of fish 2 , 55 , and studies show that the round goby successfully predates hard-bodied prey species such as marbled crayfish 56 , spiny-cheek crayfish 54 and signal crayfish; especially the size of the goby’s mouth gape acts as a limiting factor for swallowing crayfish 57 . However, we lack knowledge of the behaviour of crayfish as prey when they detect the chemical cues emitted by fish predators, which help them evaluate the degree of danger in the environment.…”

“…Understanding the response of the invasive marbled crayfish to the presence of the invasive round goby—and predatory fish in general—may help us understand, predict and possibly manage ongoing changes occurring in invaded freshwater ecosystems. The ethological effects of the presence of round goby, which include high feeding pressure on marbled crayfish 56 , competition for shelter, and other direct and indirect consequences of co-occurring invasive crayfish 11 , 54 , may result in behavioural alterations in crayfish and changes in invaded ecosystems. In addition to the aforementioned impacts, detailed accounts of additional impacts are reported in the literature.…”

Comparison of Behavior and Space Use of the European Bullhead Cottus gobio and the Round Goby Neogobius melanostomus in a Simulated Natural Habitat

“…In most cases, the round goby is a more successful species in natural conditions than the European bullhead and other cottiids [39,40]. It is generally assumed that the main drivers of the successful competition of the round goby have higher adaptability to alternative food sources as showing non-selectivity when consuming various size preys (e.g., macrozoobenthos crayfish) [58,59], fast growth and early sexual maturation, leading to rapid formation of dense populations [9,35]. Little is known about the effects of flow velocity and shelter availability on competition between the European bullhead and round goby, and these factors may be crucial for their potential co-occurrence in freshwaters and even for the persistence of the European bullhead in European waters.…”