The occurrence of plastic pollution in the Southern Ocean has been proven in almost all environmental compartments (1) which highlights this region is not as isolated from the rest of the world as previously considered.
Being well adapted to extreme but stable environmental conditions, with unique phenotypic traits, Antarctic organisms are considered more vulnerable to environmental perturbations and pollutants compared to species from lower latitudes (2). Thus, microplastics may pose a significant threat to Antarctic marine biota.
This study will examine the interaction between gelatinous zooplankton (i.e. jellyfish appendicularians and salps) and microplastic debris in the Scotia Sea, at the northern edge of the Southern Ocean.
Gelatinous zooplankton exhibit higher feeding rates than other marine planktonic herbivores and predators, ingesting particles over a wide range of sizes and types. They are abundant and ubiquitous in the all the world’s oceans and can rapidly reach high population densities or blooms. Laboratory feeding studies demonstrate that gelatinous zooplankton can ingest (3) and package microplastics into sinking aggregates. Furthermore, these organisms may perform significant vertical migrations and consequently actively act as biological vectors of microplastic from the surface to the deep ocean and in turn promote the penetration of plastic to the benthic community.
This study will analyze the role of gelatinous zooplankton as a microplastic conduit within the Antarctic foodweb and as vectors of microplastic penetration to the deep ocean.
The specific objectives will include:
1-Zooplankton net samples will be analysed in order to estimate the amount of plastic within gelatinous zooplankton. The characteristics of microplastics will be investigated by digestion and FTIR (Fourier-transform infrared spectroscopy) techniques.
2-Stable isotopes and fatty acid tracer techniques will be used to determine gelatinous zooplankton dietary sources in order to estimate potential relationships between food sources and microplastic assimilation.
3-Zooplankton stratified multinet samples will be analysed to estimate abundance, vertical distribution and biomass of gelatinous organisms both day and night, so as to parameterise the influence of diel vertical migration on the penetration of oceanic plastic to depth.
4-Neuston net and floating sediment trap samples will be analysed to quantify microplastic abundance through the water column to determine potential encounter rates between microplastics and gelatinous zooplankton.
There may be the opportunity to undertake fieldwork as part of as part of a BAS long-term observation programme, to collect microplastic and zooplankton samples within the Scotia Sea (Southern Ocean). However, should this not be possible, the PhD can be completed using historical samples already archived by BAS.
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 British Antarctic Survey (BAS). Specific training will include: Isotope and fatty acid sample preparation, clean laboratory chemistry, FTIR microplastic analysis, carbon analysis and gelatinous zooplankton identification. The student will join the Ecosystems group at BAS where he/she will get training in Southern Ocean carbon cycle and zooplankton ecology and will have the opportunity to work with the gelatinous zooplankton Group at UoS. If fieldwork in the Southern Ocean is undertaken, this will include at-sea training in sampling zooplankton, handling specimens, manipulating experiments.
1-Tirelli et al. 2020, Microplastics in the polar samples, Handbook of Microplastics in the Environment
2-Rowlands et al., 2020, A Polar outlook: Potential interactions of micro- and nano-plastic with other anthropogenic stressors, Science of the total environment
3-Brandon et al., 2020 Patterns of suspended and salp‐ingested microplastic debris in the North Pacific investigated with epifluorescence microscopy, Limnology and Oceanography letters