Aquatic invasive species (AIS) pose a significant threat to biodiversity and production from large-scaled lake and river ecosystems. AIS cause species extinctions, increase homogenization of biological communities, decrease native biotic resistance to disruptions, outcompete heterospecifics for limited prey, eat larvae or eggs of natives and parasitize native hosts. One recent and now widespread successful invader in North American Laurentian Great Lakes (hereafter Great Lakes) and many large European waterbodies is the Ponto-Caspian round goby (Neogobius melanostomus; Figure 1).
This small (max 200 mm total length) omnivorous benthic fish was first discovered in the Detroit River in 1992 (Jude et al., 1992) and has since spread nearly ubiquitously across the Great Lakes (Figure 2).
Figure 2: Heat map showing the spread of Round Goby in the Great Lakes since discovery in 1992. Zoom in for effect. (Credit: The Nature Conservancy)
Likewise, there has been recent concern as round goby continue to invade major European waterways including along an ongoing southern invasion front in the Danube River and Rhine Rivers (Figure 3, modified from Kalchhauser et al., 2014).
At the 57th Annual Meeting of the International Association of Great Lakes Research (IAGLR; Hamilton, Ontario 2014), a session was held specific to round goby with the intent to increase awareness and understanding of ongoing ecological impacts of this AIS in the Great Lakes and in large-bodied European aquatic ecosystems. Presentations showcased the most recent research on round goby and several researchers presented research conducted as part of a nation wide directive on tackling invasive species: the Canadian Aquatic Invasive Species Network (CAISN http://www.caisn.ca/en/index.php).
Dr. Vladimír Kováč from the Department of Ecology at Comenius University in Bratislava, Slovakia, gave the first talk entitled: “Ten years of successful invasion of round goby in the River Danube.” As Europe’s second longest river (2,872 km) the Danube is an ideal route for biological invasion. Kováč’s research has addressed variability in round goby morphology, life-history, feeding ecology, phenotypic plasticity and determines how these factors have had, or continue to influence past and ongoing invasion successes. Round goby have highly specialized large eggs with dense yolks, large sizes at first feeding, high parental investment and long juvenile periods – traits that likely increased its success as an AIS. Kováč also found round goby from the invaded Slovak portion of the Danube to be smaller at maturity than most native populations from the Black and Azov seas, a pattern similarly observed for invasive Detroit River populations (MacInnis and Corkum 2000). Concordant with the session theme, Kováč found round goby consumed specialized prey types where such prey were abundant but observed also that they can shift back to generalized feeding strategies across locations or seasons when such prey are absent or decrease in abundance. Accordingly, diets of newly established round goby in the Upper and Middle Danube strongly differed from diet in native ranges. Relative abundance of round goby appears low in native European habitats and much higher in newly invaded habitats as a function of distance from native habitat (Figure 4, Kováč 2014).
A second international researcher at the session conference had characterized the potential economic impacts from a round goby invasion into Lake Zurich using multivariate modelling and found that losses could be as high as about 11% of respective annual revenues (Figure 5; N’Guyen et al., 2014).
The majority of research talks in the IAGLR round goby session were focused upon studies occurring in the Great Lakes. Talks and research results related to round goby: pheromones and olfaction (Zielinski et al., 2014); roles as prey species in avian botulism dynamics (Essian et al., 2014); PCB toxicology and bioenergetics modeling (Droulliard et al., 2014); video-capture of potential egg predation on mid-lake spawning reefs in Lake Michigan (Cole et al., 2014); and as an increasingly important prey by biomass and number for native piscivores such as burbot (Lota lota; Hares et al, 2014). Qualitative and quantitative diet analysis of larval stage (9-23 mm total length) round goby revealed that populations from nearshore Western Lake Michigan and from regional inshore tributaries had different diet compositions (Olson et al., 2014). In lab-based experiments at the University of Windsor (Ontario, Canada), Stephenson et al. (2014) found that larval round goby yolk sac absorption took 15 days at 15° C, 9 days at 20° C and only 2 days at 25° C and observed increased nighttime activity.
Session co-chair Pettitt-Wade et al. (2014) highlighted how the dietary niche breadth of AIS determined from stable isotope content of tissues can be used to predict the likelihood of establishment and range expansion. Carbon (δ13C) and nitrogen (δ15N) stable isotopes are routinely used in trophic and food web ecology as tracers of diet history (Fry, Stable Isotope Ecology. 2006), and can be used in combination to represent the niche of an organism (or ‘isotopic niche’; Newsome et al. 2007). This presentation was one of two that compared the isotopic niche of round goby with another species of goby that is also invasive in the Great Lakes Basin but less geographically widespread; the tubenose goby (Proterorhinus semilunaris). Round goby were suggested to have a wider geographic establishment because of a broader and more flexible dietary niche (termed niche plasticity). Round goby populations in Lake St. Clair and Western Lake Superior were also found to feed at higher trophic levels than similarly sized spatially overlapping populations of tubenose goby. The onset of niche plasticity in round goby was delayed until larger body size, which increased niche overlap with smaller round goby and tubenose goby thus increasing potential for resource competition (Figure 6, Pettitt-Wade et al., 2014). Pettitt-Wade et al. (2014) concluded that the broad and plastic dietary niche of round goby characterize why this AIS is so widely established where others, such as the tubenose goby, are not.
Another session co-chair, Wellband et al. (2014), used a comparative approach to examine whether genetic diversity of round and tubenose goby measured at individually distinct microsatellite markers was higher for populations of each species in their native European habitats compared to invaded Great Lakes habitats. Spatial and temporal comparisons of genetic diversity for central and range-edge populations of round gobies demonstrates a high genetic diversity throughout their invaded range yet this range appeared higher and larger in samples from native habitats. Additional preliminary results appear to suggest that tubenose gobies have reduced genetic diversity compared to round gobies but, like round goby, tubenose goby also appeared to have higher genetic diversity in its native range. Wellband et al. (2014) concluded that the genetic diversity of each species as well as from introduced populations may have been an important initial factor, or continues to be an important ongoing contributing factor to the differential success in the comparative spread of round goby vs. tubenose goby in the Great Lakes (Figure 7, Wellband et al., 2014).
The session concluded with Janssen and Jude (2014) who suggested round goby are here to stay. It’s well known that round goby now are an important predator integrating mostly otherwise unconsumed invertebrate AIS biomass (such as dreissenids) in their diet and that round goby in turn are consumed as prey in high numbers by many native and non-native piscivores. Much like the Great Lakes AIS alewife (Alosa pseudoharengus) which is the main/only prey able to support a stocked chinook salmon (Oncorhynchus tshawytscha) fishery, and which is an AIS that also has multiple, numerous negative impacts on other less-valued naïve aquatic species, scientific decision makers might be faced with similarly difficult choices in the future management of round goby in the Great Lakes as they become increasingly integrated in food webs and diets of valued sport and commercially caught fishes. Janssen and Jude (2014) suggest one strategy to control round goby populations in the Great Lakes might be to stock native fish predators that consume high numbers of round goby including smallmouth bass (Micropterus salmoides) or stock other native round goby predators such as Lake Erie water snakes (Nerodia sipedon insularum). Furthermore, they suggested that such predators may learn to work together to increase capture rates. Whether or not round goby may be stocked or managed in a contextual role as an important forage fish for predators despite its many negative impacts as an AIS in the future is doubtful (Figure 8, Janssen and Jude 2014), but captures some of the many difficulties faced in managing AIS such as this which have the ability to spread widely and proliferate on a dramatic scale.
Featured Image: Palisade Head on the North Shore of Lake Superior. (Credit: U.S. Environmental Protection Agency via Wikimedia Commons)
- Jude, D. J., R. H. Reider and G. R. Smith. 1992. Establishment of Gobiidae in the Great Lakes basin. Canadian Journal of Fisheries and Aquatic Sciences. 49:416–421
- Kalchhauser, I., P. Mutzner, P. E. Hirsch and P. Burkhardt-Holm. 2013. Arrival of round goby Neogobius melanostomus (Pallas, 1814) and bighead goby Ponticola kessleri (Günther, 1861) in the High Rhine (Switzerland). Bio Invasions Records. 2:79-83.
- MacInnis, A. J. and L. D. Corkum. 2000. Age and growth of round goby, Neogobius melanostomus, in the upper Detroit River. Transactions of the American Fisheries Society. 129:852-858.
- Fry B (2007) Stable isotope ecology. Springer, New York
- Newsome SD, Martinez del Rio C, Bearhop S, Phillips DL (2007) A niche for isotopic ecology. Frontiers in Ecology and the Environment 5:429–436. doi: 10.1890/060150.01
References for Presentations:
- Cole, K.M., T. L. Galarwicz, R. M. Claramunt, W. L. Chadderton, M. E. Herbert, A. J. Tucker and J. A. Gross. (2014). “Spatial and temporal distributions of the invasive Round Goby (Neogobius melanostomus) and Rusty Crayfish (Orconectes rusticus) on critical spawningreefs.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Droulliard, K. G., J. A. O’Neil, X. Sun, T. B. and Johnson. (2014). “Use ofPCBs as metabolic tracers to estimate field metabolic rate of round goby (Neogobius melanostomus) during temperature acclimation.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Essian, D., B. Moraska LaFrancois and J. B. K. Leonard. (2014). “Diets of botulism affected piscivorous birds on Lake Michigan.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Hares, C. and J. B. K. Leonard. (2014).“Round Goby Replacing Native Fauna as Main Littoral PreyItem of Burbot in eastern Lake Michigan.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Kováč, V. (2014). ”Ten Years Of Successful Invasion Of Round Goby Neogobius Melanostomus In The River Danube (Central Europe) – A Review.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- N’Guyen, A., P.Hirsch, I. Kalchhauser and P. Burkhardt‐Holm. (2014). “Estimating potential economic impacts of a goby invasion.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Janssen, J. and D. J. Jude. (2014). “Goby lemonade.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Olson, D.S. and R. A. Dillon. (2014). “The Diets of Hatchling Round Gobies in Western Lake Michigan.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Petittt-Wade H., K. W. Wellband, D. D. Heath and A. T. Fisk. (2014). “Isotopic Niches and Potential for Dietary Plasticity in Round Goby andTubenose Goby in The Great Lakes.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Stephenson, S.L., L. D. Corkum,Y. Zhao and J. H. Ciborowski. (2014).“Effects of temperature on round goby (Neogobius melanostomus) larval survival,development and distribution.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Wellband, K.W., H. Pettitt-Wade, A. T. Fisk and D. D. Heath. (2014). “Is Genetic Diversity a Predictor of Invasion Success? A Case Study ofGobies in the Great Lakes.” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.
- Zielinski, B.S. (2014). “The scent of a man (Neogobius melanostomus).” 57th Annual Conference on Great Lakes Research (IAGLR 2014), Hamilton, Ontario.