A long-term time series of microplasitcs: An investigation into ingestion of microplastics by the Antarctic cushion star Odontaster validus

Abstract

Plastic remnants are a serious environmental contaminant that may impact organisms across all trophic levels globally. Long-term investigations into the proportion of plastic entering ecosystems are difficult, in part due to the relatively new discovery of the impact plastics have, and because of the complex nature of interactions between coastal ecosystems and the generally dense placement of human settlements. A better understanding of the interactions between microplastics and organisms of different feeding ecologies and trophic levels will be key to understanding the mobility of microplastics through trophic systems. Samples of the Antarctic cushion star Odontaster validus were collected next to Rothera Research Station, Adelaide Island (British Antarctic Survey, 67° 34' 12"S 68° 07' 12"W) over a 23-year period and their pyloric caeca processed to quantify microplastic loading. Plastic particles were quantified and categorised by type and polymer composition using UV microscopy and Laser Direct Infra-Red (LDIR) techniques, respectively. Peak average plastic density (376.65 particles/g of tissue) was observed after a fire in the station’s Bonner Laboratory in 2001, whereas the lowest average plastic level (11.8 particles/g of tissue) coincided with the implementation of new waste management strategies in 2019. A relationship between plastic density and pyloric caeca weight (f(2,294) = 143.8, adjusted r2 = 0.49, p < 0.05) suggests that plastic uptake changes based on physiological factors, which should be considered when measuring species-wide plastics uptake. Environmental factors also impacted these data. For example, a positive relationship was observed between plastic density and ice scour (f(2,238 = 4.7, adjusted r2 = 0.03, p < 0.05) mediated by the cushion star’s feeding ecology. These data demonstrate the complexity of the microplastics problem even when studying the relationships between plastics and isolated ecosystems, while affirming the idea that sustainability efforts can lessen the introduction of plastic pollutants into the ecosystem.

Date of Award	11 Feb 2025
Original language	English
Sponsors	HEFCW
Supervisor	Christian Dunn (Supervisor), Laura Grange (Supervisor) & Davey Jones (Supervisor)