How will microplastics affect marine copepods and their contributions to global biogeochemical cycles?

Dr Daniel Mayor, Dr Kathryn Cook, Dr Jasmin Godbold, Dr Andrew Yool, Dr Alice Horton
Rationale: 

Marine copepods are possibly the most abundant group of animals on Earth and their total global biomass is many times greater than that of the whole human population. Copepods are fundamental to the productivity and biogeochemistry of the global ocean; they consume ~12% of global annual primary production and their faecal pellets constitute >60% of the global export of organic matter that sequesters atmospheric carbon in the deep ocean. They also form the principle trophic interface between primary producers and countless species of higher predators including many commercially important fish stocks, birds and mammals [1]. Understanding the physiology of marine copepods, and how it changes in response to perturbations, is therefore important to predicting the future functioning of the wider Earth system. Recent modelling work suggests that microplastics may reduce copepod grazing on primary producers, with consequences for biogeochemical cycling in the global ocean [2]. However, significant uncertainties remain in our understanding of how microplastics affect copepod feeding and their energy budgets. This project aims to fill this knowledge gap; focused laboratory experiments will examine how microplastic pollution affects the feeding, respiration, excretion and egg production of marine copepods, helping to reduce uncertainties in understanding the impacts of microplastics at the global scale.

 

Methodology: 

Laboratory culture experiments will be used to quantify how the presence of different microplastic concentrations, particle shapes, and polymer types affect important physiological processes in copepods, including respiration, excretion, ingestion, prey selection, egg production, absorption efficiencies and faecal pellet production. Analysis of preserved animals from a range of locations throughout the Atlantic Ocean, from the Arctic down to the Southern Ocean, will determine the range of microplastic concentrations observed within contemporary marine copepods. The understanding generated will be used in collaboration with marine ecosystem modelers to develop a new zooplankton parameterization for use in the IPCC-class global biogeochemical model, MEDUSA [3]. This will allow the student to quantify how future ocean microplastic scenarios may affect the production and biogeochemical cycling of marine ecosystems. We also anticipate opportunities for the student to collect additional plankton samples/conduct experiments on forthcoming research cruises (e.g. North Atlantic, Southern Ocean) during their PhD.

 

Location: 
NOC Southampton
Training: 

The INSPIRE DTP programme provides comprehensive personal and professional development training alongside extensive opportunities for students to expand their multi-disciplinary outlook through interactions with a wide network of academic, research and industrial/policy partners. The student will be registered at the University of Southampton and hosted at the National Oceanography Centre, in the Ocean Biogeosciences group. The Ocean Biogeosciences group is renowned globally as one of the leading centres of excellence in biological carbon pump research with plankton ecologists, numerical modellers, remote sensing specialists, theoreticians and particle flux geochemists working together to address the most significant problems in contemporary biological oceanography. Specific training will include: plankton culturing techniques, experimental design, zooplankton sampling, statistical skills and R programming. Additional training in elemental- and inorganic nutrient analysis, the use of optodes and processing plankton samples using semi-autonomous FlowCam technologies will also be provided.

Eligibility & Funding Details: 

Please see https://inspire-dtp.ac.uk/how-apply for details.

Background Reading: 

[1] Steinberg & Landry, 2017. Zooplankton and the ocean carbon cycle. Annu. Rev. Mar. Sci. 2017. 9:413–44.

[2] Kvale et al., 2021. Zooplankton grazing of microplastic can accelerate global loss of ocean oxygen. Nature Comms. 12: 2358.

[3] Yool et al. Yool, A., Palmiéri, J., Jones, C. G., de Mora, L., Kuhlbrodt, T., Popova, E. E., Nurser, A. J. G., Hirschi, J., Blaker, A. T., Coward, A. C., Blockley, E. W., and Sellar, A. A.: Evaluating the physical and biogeochemical state of the global ocean component of UKESM1 in CMIP6 historical simulations. Geosci. Model Dev., 14, 3437–3472.