Differences in predator-avoidance behavior between two invasive gobies and their native competitors

Abstract

Globally, fish are frequently introduced beyond their native range. Some, like Ponto-Caspian gobies, are becoming invasive, achieving high colonization rates and constituting frequent prey for native predators. However, little is known about the effectiveness of antipredator behaviors of the invaders, which may shape their role in the invaded community and contribute to the invasion success. We compared antipredator behaviors of invasive gobies and native fish species after their detection by the predator, when the danger becomes direct. We studied 2 fish pairs, each consisting of an invasive and native species co-occurring in the environment and belonging to the same prey guild: (1) the racer goby Babka gymnotrachelus versus European bullhead Cottus gobio, (2) the monkey goby Neogobius fluviatilis versus gudgeon Gobio gobio, facing a naïve predator (the Eurasian perch Perca fluviatilis). We analyzed behaviors of single prey individuals (escaping, staying in shelter, and activity) and single predators (activity, searching, following, capturing, and latency to prey consumption). In the predator presence, the bullhead was less active and more often managed to escape after capture than the racer goby. The gudgeon escaped before the capture more often than the monkey goby. The predator succeeded later with the bullhead compared to racer goby, whereas no differences in ingestion time occurred between the gudgeon and monkey goby. The results suggest that, in terms of hunting effort of native predators, the invasive gobies are equivalent to or more profitable prey than their native analogs, which can facilitate the integration of the gobies into local food webs.

Keywords: antipredator behavior; fish behavior; invasive prey; native predator; predator–prey interactions.

Figure 1.

Experimental setup. The predator (perch) was placed in an experimental tank alone to acclimatize. A single prey individual was placed always inside a mesh cylinder acting as a hideout for prey (A). During a single trial, a perch individual was confronted with both prey species from the pair (one after another) in a sequence varying among replicates (native before invasive or invasive before native). Dimensions are given in centimeters.

Figure 2.

Experimental procedure. 1—releasing the predator (perch) to the tank; 2—the first feeding of the predator with Chironomidae larvae ad libitum; 3—placing the first prey individual in the tank; 4—the second feeding of the predator with Chironomidae larvae ad libitum; 5—placing the second prey individual (of different species than in step 3) in the tank. White rectangles indicate predator acclimation periods. Numbers in circles and gray rectangles indicate the recorded and analyzed periods (rounds) of the trial.

Figure 3.

Behaviors of the European bullhead (blue/light) and racer goby (red/dark) (A, B) as well as of their predator (perch) (C–E). A—prey activity; B—prey escape; C—predator activity; D—predator efficiency of attacks; E—delay in predator success. Asterisks indicate significant differences: *P < 0.05, **P < 0.01, ***P <0.001 (see online for color figures).

Figure 4.

Behaviors of the gudgeon (blue/light) and monkey goby (red/dark) (A, B), as well as of their predator (perch) (C, D). A—prey activity; B—prey escape; C—predation intensity; D—predator activity. Asterisks indicate significant differences: *P < 0.05, **P < 0.01, ***P < 0.001 (see online for color figures).