Seasonal habitat use indicates that depth may mediate the potential for invasive round goby impacts in inland lakes

Abstract

The round goby (Neogobius melanostomus) is among the fastest‐spreading introduced aquatic species in North America and is radiating inland from the Great Lakes into freshwater ecosystems across the landscape. Predicting and managing the impacts of round gobies requires information on the factors influencing their distribution in habitats along the invasion front, yet this information is not available for many recently invaded ecosystems. We evaluated the seasonal habitat use and biomass of round gobies in an inland temperate lake to define the spatiotemporal scope of biological interactions at the leading edge of the round goby invasion. Using novel statistical approaches, we combined hierarchical models that control for imperfect species detection with flexible smooth terms to describe non‐linear relationships between round goby abundance and environmental gradients. Subsequently, we generated accurate detection‐corrected estimates of the standing stock biomass of round gobies. Our results show seasonally differentiated habitat niches, where suitable round goby habitat in summer months is restricted to shallow depths (<18.4 m) with a mixture of vegetative and mussel cover. We found high round goby biomass of 122 kg/ha in occupied habitats during the summer, with a total lake‐wide biomass of 766,000 kg. In winter, round gobies migrate to deep offshore habitats and disperse, dramatically altering their scope for biological interactions with resident aquatic species across summer and winter seasons. The results of this study indicate that the scope of biological interactions in inland lakes may be seasonally variable, with potential for high round goby biomass in shallow lakes or at the periphery of deep lakes in the summer months. Such shallow‐water habitats may therefore present higher risk of ecological impacts from round gobies in invaded lentic ecosystems. As round gobies expand inland, consideration of seasonal habitat use will be an important factor in predicting the impacts of this pervasive invader.

Seasonal depth distribution and thermal experience of the non-indigenous round goby Neogobius melanostomus in the Baltic Sea: implications to key trophic relations

“…This ultimately reveals a pronounced seasonal migration between shallow coastal waters and offshore areas, which can be related directly to different thermal conditions between the seasons. This finding mirrors the annual inshore/offshore seasonal migration of round goby documented in some North American lakes (Andres et al 2020, Pennuto et al 2021) and previously suggested in Europe (Sapota and Skora 2005;Christoffersen et al 2019). These migration events have been shown to translocate significant amounts of energy, prey, and nutrients in a range of lake sizes (Johnson et al 2005, Andres et al 2020, Pennuto et al 2021.…”

“…This finding mirrors the annual inshore/offshore seasonal migration of round goby documented in some North American lakes (Andres et al 2020, Pennuto et al 2021) and previously suggested in Europe (Sapota and Skora 2005;Christoffersen et al 2019). These migration events have been shown to translocate significant amounts of energy, prey, and nutrients in a range of lake sizes (Johnson et al 2005, Andres et al 2020, Pennuto et al 2021. ECThe deepest location previously recorded was 130 m in the North American Great Lakes (Walsh et al 2007) (although based on much less extensive spatial data), as opposed to 90 m in the Baltic Sea in this study.…”

“…Our results show pronounced seasonal migration of the round goby from the very shallow coastal areas to the deep offshore regions and vice versa, similar to findings in North American freshwater environments (Andres et al 2020, Pennuto et al 2021. Both the spatial distribution (Kotta et al 2016) as well as biomass of the round goby has increased over time in the Baltic Sea (up to 350 individuals/100m 2 ; Sapota and Skora 2004;Puntila et al 2018), which has resulted in increased translocation of organic matter and energy to deeper offshore regions over time.…”

“…Because of large areas colonized and high population sizes achieved, major effects on the native species and communities have been documented in the wake of its invasion (Crane and Einhouse 2015;Karlson et al 2007;Bergstrom and Mesinger 2009;Poos et al 2010;French and Jude 2001). Recent investigations in the Great Lakes and other inland lakes of North America show that in these environments, this species engages in annual nearshore/ offshore migrations, typically of the entire populations, and that this seasonal migration of the round goby displaces a large biomass, with substantial ecological impacts (Andres et al 2020, Pennuto et al 2021. In general, the round goby has a generalist feeding strategy and preys upon a wide range of different pelagic and benthic invertebrates (Skabeikis and Lesutiene 2015;Nurkse et al 2016) and also fish eggs and small fish (Schrandt et al 2016;Wiegleb et al 2019).…”

Nuclear eDNA estimates population allele frequencies and abundance in experimental mesocosms and field samples

“…To determine the feasibility of estimating population allele frequencies from eDNA samples in a field‐based setting, we collected eDNA samples and additional round gobies ( n = 15) from another site on Cayuga Lake (c. 20 miles away from the site of round goby collection for the mesocosm experiment; Figure A). Sampling was conducted during the summer months when round goby densities peak in nearshore waters, and density estimates from a previous study using benthic videography and direct observation report round goby densities of 0.34 fish/m 2 in this section of the lake (Andres et al, 2020). We confirmed the round gobies collected from the two sites in Cayuga Lake are panmictic using genotyped tissue samples from both sites and the “find.clusters” function of the ADEGENET package in R version 3.5 (Jombart, 2008; R Core Team, 2016), where a single cluster (k) exhibited the lowest Bayesian Information Criterion (BIC; Figure B).…”