Prediction of ecological impact of two alien gobiids in habitat structures of differing complexity

Abstract

Rapid expansion of round goby (Neogobius melanostomus) and western tubenose goby (Proterorhinus semilunaris) beyond their native ranges calls for urgent management action, particularly in localities with high introduction possibility of the species. We used a comparative functional response (FR) approach to forecast invader ecological impact. We compared their foraging efficiency in three habitat structures: sand, coarse gravel, and coarse gravel with an artificial plant. Both Neogobius melanostomus and Proterorhinus semilunaris showed type II FR in all habitats. Interspecific comparison showed similar handling times in both the gravel and gravel with artificial plant habitats, suggesting similar per capita impact. Intraspecific comparison showed significantly lower handling times of both predators on gravel substrates. Therefore, their ecological impact in such an environment could be higher. Neogobius melanostomus showed higher attack rates on sandy substrates compared with Proterorhinus semilunaris, while no significant differences were observed on other substrates. Our results highlight the importance of interacting factors in management of ecosystems with multiple invaders, as the elimination of invasive Neogobius melanostomus may lead to utilization of the empty niche by alien Proterorhinus semilunaris with similar ecological impact.

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

“…In our experimental exposures, N. melanostomus exhibited a high rate of NCM, indicating its potential role in the effect of this predator on prey population abundance and ecosystem function. Our observed NCM is in contrast with previous studies of N. melanostomus FR with fish larvae as prey [ 52 , 77 ] in which no NCM was observed. In mammals, NCM is usually connected either with an ineffective anti-predator response due to lack of co-evolution with the predator [ 101 ] or to lack of prey escape response as a consequence of isolated short-term events [ 102 ].…”

“…However, this expected phenomenon was not observed in our two prey–species system, although prey organisms displayed different escape abilities. This is consistent with Gebauer et al [ 77 ] who found no shift in N. melanostomus FR with increased habitat complexity, suggesting that N. melanostomus is a highly effective predator irrespective of habitat conditions [ 76 ] and prey behaviour (this study).…”

“…Handling time, as the ability to find and process prey, determines the predator maximum feeding rate [ 50 ]. This parameter closely correlates with habitat complexity [ 57 , 77 , 78 ] and, especially, with prey morphology and behaviour [ 53 , 79 ]. The typical crayfish flip-tail escape is generally considered a successful antipredation strategy [ 34 , 80 ] that reduces predator success or at least requires higher predator energy [ 81 , 82 ].…”

Prey type and temperature influence functional responses of threatened endemic Cape Floristic Ecoregion fishes

“…benthic chironomids with a burrowing escape strategy and water surface-dwelling mosquito larvae using movement for escape). Benthic and pelagic prey (and the substrate of the environment) present distinct challenges to successful capture by predators, and this aspect of prey behaviour can significantly affect the ability of predators to effectively exploit prey resources and therefore performance in FR trials (Gebauer et al 2019;South et al 2019). Furthermore, we expected that there would be species-specific context dependency of the FR owing to spatial differentiation between the species, i.e.…”

Round goby versus marbled crayfish: alien invasive predators and competitors

“…When co-existing fish and decapods are omnivores, there will be competition and mutual predation, depending on relative size and vulnerability (Reynolds, 2011). Bottom-dwelling fish such as round goby can potentially exert negative effects on crayfish in addition to predation, as they use similar food sources and compete for shelter (Gebauer et al, 2019). Limited shelter availability can increase the vulnerability to predation of the weaker opponent (Church et al, 2017).…”