Effects of dreissenid mussels, chironomids, fishes, and zooplankton on growth of round goby in experimental aquaria

Abstract

There is a widely accepted paradigm supported by early field and laboratory observations that the adult round goby (Neogobius melanostomus) is highly adapted to, and primarily survives on, dreissenid mussels. However, more recent stable isotope and diet analyses indicate that the round goby may not rely on dreissenid prey to the extent that was previously believed. We conducted a feeding experiment where round gobies were provided with an excess of one of four naturally occurring diets for 25 days -dreissenid mussels, juvenile fish, chironomids, or zooplankton. Round gobies fed dreissenids had significantly lower growth (À0.04 g day À1) than individuals fed fish and chironomids (0.13 g day À1 ) and displayed the same weight loss as round gobies fed only zooplankton. Although dreissenids are often consumed by round gobies, this likely happens only when more profitable prey such as fish and non-dreissenid invertebrates are lacking or difficult to capture. Additionally, field observations of round goby diets that have supported the paradigm may overestimate the importance of dreissenid prey due to the longer retention time of shells in round goby guts compared to other soft-bodied prey. Our results provide direct evidence supporting recent findings that dreissenid mussels may not be as essential to round goby survival as previously considered.

Predator and prey: the role of the round gobyNeogobius melanostomusin the western Baltic

“…In our study, the percentage of bivalves might be overvalued in the diet of round goby because their shells are indigestible and have a longer retention time in stomachs compared to soft-bodied prey. Moreover, they are easier to identify (Coulter et al 2011;Brush et al 2012). Another critical aspect is that the digestive process continues during the catch period (Baker et al 2014); therefore, fish were frozen immediately after capture and the fishing time of the gillnets was minimized to less than 24 hours.…”

Twenty years of invasion: a review of round gobyNeogobius melanostomusbiology, spread and ecological implications

“…In lakes and seas (lentic habitats), molluscs are usually the primary diet component (mean of 57·0 and 64·5% by mass in the Laurentian Great Lakes and Eurasia, respectively). In a laboratory study, however, N. melanostomus that were fed only dreissenids had lower growth rates (−0·04 g day −1 ) than those fed only chironomids (0·13 g day −1 ), suggesting dreissenids may be primarily consumed when more profitable prey are rare or difficult to capture (Coulter et al , 2011). Neogobius melanostomus can crush mollusc prey with the pharyngeal teeth (Ghedotti et al , 1995) with field studies indicating c. 50% of mussels consumed by N. melanostomus are crushed v. 50% swallowed whole (Andraso et al , 2011).…”

Invasion strategy and abiotic activity triggers for non-native gobiids of the River Rhine

“…Round goby may outcompete tubenose and bighead goby by sheer number, size, and overcrowding of available space. In addition, while round goby shares a number of food resources with tubenose and bighead goby, including zooplankton (as juveniles), benthic invertebrates, small fishes and the eggs and larvae of large fishes [ 10 , 31 ], they can also consume mussels when more profitable prey is rare or difficult to capture [ 32 ]. In the study area, invasive dreissenids (zebra mussel Dreissena polymorpha and quagga mussel Dreissena rostriformis bugensis ), are building huge stocks [ 33 , 34 ] and provide a potentially important food source for round gobies, thus boosting their competitive advantage and providing a convincing explanation for the observed decline in tubenose and bighead gobies following the arrival of round goby.…”