Forecasting the effects of global change scenarios on bioaccumulation patterns in great lakes species

Abstract

Climate change will have substantial impacts on biodiversity, particularly for aquatic species. Warming temperatures and changing weather patterns will also remobilize and modify chemical partitioning. Holding millions of cubic yards of sediments contaminated with persistent legacy chemicals such as polychlorinated biphenyls (PCBs) and dioxins, the Laurentian Great Lakes are a laboratory for observing interactions between biological and chemical responses to climate change. They provide a wide range of habitat to a variety of species, from littoral forage fish to deep-water predators. In this paper, we couple bioenergetic and bioaccumulation models to investigate the biological and chemical effects of climate change in the Great Lakes. We consider three species: round goby, a warm-water invasive forage fish; mottled sculpin, a cool-water native forage fish; and lake trout, a cold-water native predator. Using our coupled models, we calculate the accumulation of a representative persistent chemical, PCB-77, under four climate scenarios for Lake Erie and Lake Superior. Predator-prey (lake trout-round goby) interactions and food availability (high-low) are incorporated into our simulations. For cool-to cold-water species (sculpin, lake trout) we find that warm temperatures limit growth. For warm-water species (round goby) cold temperatures limit growth. The impact of climate warming on growth depends on the winter lows as well as the summer highs of the scenario, in combination with the species' critical upper and lower thermal limits. We find conditions for high growth and consumption rates generally lead to high bioaccumulation. However, this can be confounded by predator-prey dynamics, as mismatches in the temperature preferences of predator and prey can lead to mismatches in relative growth and uptake rates. As predator-prey dynamics are expected to undergo substantial shifts with changing climate, these relative thermal sensitivities will be key in determining the implications of climate change for bioaccumulation, particularly in top predator species.

The role of winter phenology in shaping the ecology of freshwater fish and their sensitivities to climate change

“…At higher trophic levels, initial increases in richness will promote changes in predation and competition pressures that can strongly affect final community composition. Sharma et al (2007) argued that increased predation by invading smallmouth bass would pose a serious threat to native cyprinid species (as per Jackson 2002), while Ng and Gray (2011) argued that climate driven shifts in predator-prey relationships could cause increased bioaccumulation of persistent chemicals in freshwater food chains. Buisson and Grenouillet's (2009) study of climate change impacts on French rivers suggested that species diversity would increase more than trait diversity in many locations, leading to increases in the overall intensity of competition for resources (e.g.…”

Influence of global climate change on chemical fate and bioaccumulation: The role of multimedia models

“…Ng and Gray 17 focused their investigation of bioaccumulation and climate change on the impact of projected temperature increases in the Great Lakes on the metabolic rates of fish with different thermal sensitivities. Their study considered only PCB-77 and did not consider changes in the productivity or organic carbon content of the water column.…”

“…Consumption and growth rates, which are positively correlated in bioenergetics models but negatively correlated in bioaccumulation models, were predicted to have a balancing effect on the influence of temperature on chemical concentrations in biota. Changes in PCB-77 concentrations in fish due to projected temperature shifts in Lake Erie and Lake Superior were relatively small, particularly when compared with potential changes in food availability and food type 17. Metabolic effects (temperature effects on the rate of chemical uptake and loss) were confounded by trophic interactions among species with different thermal sensitivities, indicating possible effects of invasions of warm-water species into warming higher-latitude territories 17.…”

“…Potential changes in food-web structure, which affect bioaccumulation via exposures encountered in the diet, can at times be difficult to predict, resulting in challenges with respect to integrating biological information across many organisms at different trophic levels 78. The within-organism impacts of GCC due to changes in bioenergetics rates have been previously explored by Ng and Gray 17 for several species and a single chemical. Their methods are expanded here (see Supplemental Data for details) to explore the potential impacts of GCC on the bioaccumulation in an organism of a wide range of chemicals.…”

“…These can be broadly classified into three regions, illustrated in Figure 4A for the round goby ( Apollonia melanostomus ) 17: (1) the lower critical thermal limit (CT min ), (2) the optimal temperature(s) for growth (T opt ), (3) and the upper critical thermal limit (CT max ). In terms of maximizing consumption and growth, the longer time spent near T opt , the better.…”