The Distribution and Fate of Microplastic Pollution in Polar Environments: From the Canadian Arctic to the South Pole

A multitude of concurrent stressors pose a pernicious, global threat to marine ecosystems /services and understanding the synergic impact of these environmental perturbations to marine biota remains a major challenge. The negative impact of Ocean Acidification (OA) and microplastics on zooplankton function and health has been already recognised (i.e. Manno et al. 2016; Cole et al. 2016). Recently, It has been hypothesised that zooplankton (and their faecal pellets) may play a significant role in the vertical flux of microplastics in pelagic ecosystems (Clark et al. 2016). However the synergistic impact of both anthropogenic stressors is still unexplored. The Southern Ocean (SO) is predicted to be particularly affected by OA due to naturally high CO2 ocean uptake and low carbonate saturation levels. Further, the SO has been highlighted as a region in which microplastics will have significant overlap with biota (Worm, 2015). Within the SO, the Northern Scotia Sea contains the largest seasonal uptake of atmospheric carbon dioxide measured yet. In this region, zooplankton can contribute significantly to the deep ocean carbon export (trough production of fast sinking faecal pellets) and to the food web (because key prey to high trophic level predators). A negative impact of the anthropogenic multi-stressors on the zooplankton community may in turn affect both marine ecosystem and biogeochemical cycles.
Rationale and resources: to investigate the multi-stressors effect of OA and microplastics on key zooplankton taxa (copepods and pteropods) in the Northern Scotia Sea. The potential effect on the carbon export to the deep ocean will also be investigated. The successful candidate will work on the sediment trap samples archive at BAS. The candidate will participate in one SO sampling campaign for which he/she will receive training in sea-survival techniques. On board, the student will participate in collection of zooplankton net samples and run incubation experiments.
Specific objectives:
1. To assess physiological response to the synergic impact of anthropogenic stressors: During a sampling campaign, the student will undertake incubations of zooplankton in manipulated seawater to examine their response to the simulated OA and microplastic synergistic stress. The measurements will include mortality, respiration rates, ammonia excretion rates, faecal pellets production and egg production. Stable isotopes analysis will be performed on samples to identify the effect of stressors exposure on the isotopic signature.
2. To quantify the role of zooplankton as drivers of microplastics to the deep ocean- The PhD candidate will assess the seasonal and interannual variability of "microplastic flux" to the deep ocean by investigating samples collected from deep moored sediment traps (1500-2000 m). He/she will quantify the total microplastic amount in the sinking particles and the specific contribution included in faecal pellets and zooplankton carcasses.
References
-B. Worm, Silent spring in the ocean Boris Worm, PNSA, 112, 752-11753 (2015)
-J. R. Clark, M. Cole, P. K Lindeque, J. Blackford, E. Fileman, C. Lewis, T. M Lenton and T. S. Galloway, Marine microplastic debris: a targeted plan for understanding and quant