The flux of microplastics in the Southern Ocean: the role of gelatinous zooplankton

Lead supervisors: Dr Clara Manno

Location: Ecosystems, British Antarctic Survey (BAS)

Duration: 8 weeks

Suitable undergraduate degrees: Environmental science, marine biology

Project background

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.

Objective: This study will assess the role of gelatinous zooplankton as vectors of microplastic penetration to the deep ocean. The work will be performed in the frame of the FLF UKRI funded project CUPIDO (Calculating the strength of the Plastic pump In counteracting the Deep export of Oceanic carbon), focus on the role of zooplankton in promoting the vertical flux of plastic in the ocean.

Methods: samples previously collected with a multi-stratified zooplankton net (up to 1000m depth) will be analysed to estimate abundance, vertical distribution by using an optical microscope. Then, the amount of microplastic debris within gelatinous zooplankton will be quantified. The characteristics of microplastics will be investigated by enzymatic digestion (to separate microplastic from the organic component) and FTIR, Fourier-transform infrared spectroscopy techniques (to identify the different plastic polymers). The student will join the Ecosystems group at BAS where he/she will get training in Southern Ocean zooplankton ecology.