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.
Highlights
Freshwater ecosystems are extremely vulnerable to biological, chemical, and physical alterations (Bucciarelli et al 2014; Strayer 2010)
No significant differences were found between Neogobius melanostomus and Proterorhinus semilunaris in a values on gravel with artificial plant or in h values on gravel substrate
Proterorhinus semilunaris showed significantly lower a and h values on gravel, whereas no difference was found between sand and gravel with artificial plant (Tables 1 and 2)
Summary
Freshwater ecosystems are extremely vulnerable to biological, chemical, and physical alterations (Bucciarelli et al 2014; Strayer 2010). Restructuring of regulated rivers, including shoreline, flow regime, and vegetation cover (Bunn and Arthington 2002; Jansson et al 2000; Nilsson and Berggren 2000), has resulted in the loss of native species unable to adapt (Wolter 2001), increasing niche opportunities for aliens (Shea and Chesson 2002). Both habitat alterations and nonnative invasions induce changes in a range of processes such as predation (Griffen and Delaney 2007; Wootton et al 1996), which plays an essential role in organization of community ecology (Lima 1998; Polis et al 2000). Comparative FR is a useful tool for assessment, comparison, and prediction of the impact of newly introduced species (Alexander et al 2014; Dick et al 2014; Xu et al 2016)
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