Microplastic model parameter values for each simulation presented here are provided in Table 1. These three simulations are highlighted to represent the solution space of the 14 individuals of a 300 member perturbed parameter ensemble 7, 8 that produced plausible global microplastic inventories 9 and subsurface particle maxima 10, using pollution rates 11 and marine snow aggregation rates 12 within available estimates. Figure 1 displays simulated microplastic concentrations from a model that does not include biological uptake (No Bio) and from three models that do ‘Low Concentration’ (LC), ‘High Concentration’ (HC), and ‘Moderate Concentration’ (MC). This result demonstrates that a physical effect of plastic pollution might presently have a disruptive influence on global ocean oxygenation equivalent of up to half that of climate warming, and it suggests a missing mechanism in Earth system models, which typically underestimate 21st century ocean deoxygenation 2.īiological uptake has the potential to profoundly shape microplastic particle distributions in the global ocean 7, concentrating particles in biologically-active surface regions as well as in gyres, and transporting particles to the deep ocean. Here we report that the zooplankton ingestion of microplastic in those same simulations also affects ocean biological rates relevant to dissolved oxygen. They demonstrated a potentially significant influence of both marine snow (aggregated organic detrital material) and zooplankton faecal pellets in shaping microplastic distributions in the global ocean. Explicit consumption of microplastic by zooplankton, as well as microplastic aggregation in marine snow, was recently implemented in an Earth system model in order to simulate the transport of microplastic particles by biology 7. If sufficiently widespread, this reduction of grazing on primary producers might have global biogeochemical consequences. These small particles (the microplastics, typically defined as having a length between 0.1 μm and 5 mm) replace food in the zooplankton’s diet and reduce their consumption (and subsequent export) of particle-bound organic carbon 6. A growing body of work shows zooplankton consume the smaller size fractions of plastic 4, 5. Plastic pollution in the global ocean is also increasing 3. However, climate change is not the only stressor on ocean biology, and therefore biogeochemistry. Drivers of this loss have been ascribed to climate change and the associated warming and altered circulation, as well as indirect effects on biogeochemistry 2. Although significant uncertainty accompanies these estimates, the potential for physical pollution to have a globally significant biogeochemical signal that exacerbates the consequences of climate warming is a novel feedback not yet considered in climate research. Employing a comprehensive Earth system model of intermediate complexity, we estimate this additional remineralisation could decrease water column oxygen inventory by as much as 10% in the North Pacific and accelerate global oxygen inventory loss by an extra 0.2–0.5% relative to 1960 values by the year 2020. Consequently, organic particle remineralisation in these regions increases. In regions where primary production is not limited by macronutrient availability, the reduction of grazing pressure on primary producers causes export production to increase.
#Evoscan 2.9 map tracer no values shown driver
We demonstrate the potential for an additional anthropogenic driver of deoxygenation, in which zooplankton consumption of microplastic reduces the grazing on primary producers. Global warming has driven a loss of dissolved oxygen in the ocean in recent decades.
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