Food depletion regulates the demography of invasive dreissenid mussels in a stratified lake

Abstract

Lake stratification produces sharp gradients in temperature and pelagic resources which have cascading effects on the traits of aquatic populations, including invasive species and their ecosystem impacts. We study the consequences of such common environmental gradients on the demography of quagga mussels, one of the world's most aggressive invasive species. Coupling a series of in situ experiments with a biophysical model of the pelagic community, we quantify mussel growth and recruitment in littoral vs. profundal benthic habitats of eastern Lake Erie. We found that both severe food depletion and cold temperatures in the hypolimnion during summer stratification cause mussels to grow twice as slowly and currently inhibit recruitment in profundal compared to littoral habitats. Together with the high biomass and large mean mussel size found in long-term monitoring surveys in the profundal habitats, our results imply that mussels successfully colonizing profundal habitats have relatively long lifespans with low growth rates, and therefore lower productivity, compared to mussels in shallow areas. Consequently, the bulk of dreissenid biomass in Lake Erie and other Great Lakes found in the vast but resource-poor profundal habitats may have very limited impacts on epilimnetic communities compared to mussels in littoral areas. By contrast, mussels in profundal habitats strongly reduce food availability to hypolimnetic communities throughout the year. Thus, our results explain how the ecosystem impacts of sessile freshwater invaders are likely to vary among habitats and lakes depending on the relative size of profundal populations and the extent of stratification.The physiological activities of individuals both determine and reflect how species interact with and impact their ecosystem. For example, high rates of reproduction, growth, and mortality within a species correspond to a strong per capita energetic role in the ecosystem. Differences in environmental conditions or community composition across habitats can therefore produce variation in both the demographic rates of a species and its ecological role (J onasson 2004;Benton et al. 2006). This variation can be especially pronounced in widespread species with strong capacity for phenotypic plasticity, such as invasive species (Davidson et al. 2011). Consequently, ignoring demographic variation among habitats by focusing detailed population studies on specific habitats can produce a strong, unrecognized bias in the estimated ecological role of a species. The importance of this bias is especially acute for invaders rapidly expanding their distribution range, as the impacts of such species in novel ecosystems can be simultaneously strong and poorly resolved.Thermal stratification is one particularly common source of habitat heterogeneity in aquatic ecosystems. In lakes with strong stratification during productive summer seasons, species are distributed along environmental gradients from the warm, well-mixed littoral zone, where the surface mixedlayer intersects th...

Biofouling of a unionid mussel by dreissenid mussels in nearshore zones of the Great Lakes

“…Although these characteristics also describe conditions near the Saginaw rivermouth, our sampling in Saginaw Bay was much farther from the mouth of the Saginaw River. The area of influence for the Maumee rivermouth for biofouling appears to extend only about 10–15 km, after which biofouling rates are much lower, and other portions of Lake Erie appear to lack dreissenid mussel biofouling past a certain depth (Karatayev et al, 2018 ). This is also the area where flowing lotic waters are slowed by mixing with lentic waters, a zone often associated with the deposition of sediment and high primary productivity (Larson, Frost, Vallazza, et al, 2016 ; Lucy et al, 2013 ).…”

“…Our objectives were to assess (1) the degree to which overall biofouling rates vary annually in Lake Erie and (2) whether biofouling rates are similar across diverse Great Lakes nearshore areas. As a third objective, we then assessed whether biofouling varied in response to two important environmental characteristics that varied strongly among our sites (temperature and depth) and that are known to influence dreissenid mussel growth and recruitment (Karatayev et al, 2013 , 2018 ).…”

Seasonal and Spatial Variation in Growth and Abundance of Zebra Mussel (Dreissena polymorpha) in a Recently Invaded Artificial Lake: Implications for Management

“…Although the growth of zebra mussel on suspended substrates cannot be assumed to be representative of that on the bottom (Karatayev et al, 2006(Karatayev et al, , 2018, Cardiff Bay is rather shallow (mean = 4.5 m; (Olivier, 2016) and our experimental panels extended to 41-91% of the water column (mean = 67%). Most of the zebra mussel production in Cardiff Bay takes place on vertical substrates, including submerged margins, piers, docks, and boat hulls that our panels tried to mimic.…”

“…Several predators feed on zebra mussel (Wisniewski, 1974;Pedroli, 1977;Petrie and Knapton, 1999;Werner et al, 2005;Naddafi and Rudstam, 2014), but "natural enemies" alone are unlikely to regulate zebra mussel populations (Molloy et al, 1997). Densitydependent drivers like disease outbreaks (Strayer and Malcom, 2006), or food depletion caused by mussel filtration (Karatayev et al, 2018) are thought to play a much greater role in regulating the abundance of zebra mussel. Whatever the reasons, we suggest that since complete eradication will seldom be possible, local zebra mussel populations dynamics should be considered before embarking on partial removal as this may prove expensive, ineffectual, and may in some cases enhance production and aggravate the problem.…”

Mutual Facilitation Among Invading Nuttall’s Waterweed and Quagga Mussels

“…Indeed, low phytoplankton abundances (Figure 4C) might have affected the growth, recruitment and survival of quagga mussels in Müggelsee. Declining dreissenid recruitment and growth has been found following declines in food availability in the hypolimnion of Lake Erie (Karatayev et al, 2018b), so it would be worth following size-frequency distributions in the future. Higgins (2014), however, did not find evidence for diminished effects of dreissenids on ecosystems within two decades after their establishment in US waters.…”