Round goby versus marbled crayfish: alien invasive predators and competitors

Abstract

Aquatic biodiversity is threatened by spread of invasive alien species. Round goby Neogobius melanostomus is an invasive fish in large European rivers as well as in coastal waters near their mouths and marbled crayfish Procambarus virginalis is a highly invasive crustacean. Both are small, bottom-dwelling species occupying similar habitat and shelters and utilizing similar food sources. We hypothesized that goby presents a threat to both native and non-native astacofauna in invaded ecosystems. We tested this through laboratory experiments designed to determine aggressiveness and competitiveness of goby against marbled crayfish as a model for other North American cambarid crayfish, assessing goby prey size selection and competition with marbled crayfish for space and shelter. Gobies showed high aggressiveness and dominance over the crayfish. Goby predation on juvenile crayfish was limited by mouth gape size. In goby/crayfish pairs of similar weight, gobies were more aggressive, although each affected the behavior of the other.

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.…”

“…For instance, a comparative study examining the interactions between native European bullhead and non-native round goby describes the impacts in great detail 33 . Similarly, another study has explored the predation of round goby as a predator on marbled crayfish of varying size classes 57 . All the effects, including the lower food consumption in crayfish, shown in our study reflect the potential impact of invasive predatory fish on both native and non-native crayfish in freshwater ecosystems.…”

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.…”

Sustained ecological impacts of invasive crayfish following claw injury

“…Cray sh claws are essentially involved in courtship, mating (Holdich, 2002), as well as burrowing (Kouba et al, 2016), and chemoreception (Moore and Belanger, 2009). Claws are additionally critical during intra-and interspeci c interactions (Fořt et al, 2019;Roje et al, 2021), and food intake, mainly when the prey is relatively large, mobile, or hard-shelled (Keller and Hazlett, 1996;Sanders and Mills, 2022). Cray sh can lose their claws, usually via autotomy, during e.g., aggressive interactions through predator defense, or unsuccessful molting.…”