Sources, distribution and fate of microfibres on the Great Barrier Reef, Australia

Abstract

Marine microdebris, in particular microplastics (plastics <5 mm), has become an issue of international concern due to its prevalence, persistence and potential adverse impacts on marine ecosystems. Informing source reduction based on ecological effects requires an understanding of the origin, distribution and characteristics of microdebris and the interactions with marine organisms. Here we show widespread contamination of the central Great Barrier Reef environment with microdebris, with microfibres comprising 86% of all items detected. Microdebris intake by coral reef fish was non-random, with chemical composition, shape and colour differing significantly from that detected in surface waters. Furthermore, the origin of microdebris contamination in surface waters is non-random with riverine discharge a likely source for microdebris detected at inshore, but not at offshore reef locations. Our findings demonstrate the complexities associated with determining marine microdebris exposure and fate, and assist in improving future ecological assessments and prioritizing source reduction.

Microplastic Contamination Has Limited Effects on Coral Fertilisation and Larvae

“…Examination of ecologically relevant concentrations (i.e., contamination levels measured in the field) is important to ensure impacts are not overestimated and sensationalized [79]. With respect to the concentration of particles in the water column, our tests reached as high as 50 and 200 pieces L −1 (large weathered and microbeads respectively), relatively high by published environmental levels [13][14][15], indicating microplastic particles of this type present little risk to the early life processes of the coral species A. tenuis.…”

“…Emerging contaminants, such as microplastics, represent an additional stressor potentially impacting these important tropical ecosystems and their associated organisms and function [68,69]. With increasing accounts of microplastic contamination at coral reefs [2,[13][14][15]44], this experiment aimed to investigate the potential effects of two plastic types on three early life history stages of corals-fertilisation, early embryo development, and larval settlement. The experimental assays showed that short exposures to both types of microplastics exhibited minimal impacts on all three processes, even at relatively high particle concentrations.…”

“…The experimental assays showed that short exposures to both types of microplastics exhibited minimal impacts on all three processes, even at relatively high particle concentrations. Further work is required to confirm the resistance of early life processes in corals to other plastic types such as microfibres, which accounted for 86% of all micro-debris measured at reef surface waters in the central Great Barrier Reef [15].…”

“…Microplastics, which refer to plastic pieces <5 mm in size [6], can form from the breakdown of larger plastic marine debris (i.e., secondary microplastics) or enter the marine environment via wastewater containing plastic fibres from clothing, and manufactured plastic particles used in personal care products and medicinal drugs (i.e., primary microplastics [7]). Plastic degrades slowly and wide-scale dispersal of marine microplastics by wind, tidal action, and water currents [8], has resulted in global documentation of contamination throughout the water column [4,9], in Arctic sea ice [10], surface waters of the Antarctic [11], in bottom sediments [12], at tropical coral reefs, including the Great Barrier Reef (GBR, [13][14][15]), and benthic organisms [16,17], including those found in the deep-sea [18]. This widespread contamination by microplastics suggests many marine organisms may experience a range of exposure scenarios, with implications for potential adverse effects on different life history stages and feeding behaviours.…”

Effects of pollution on marine organisms

“…Many studies investigated the concentration of microplastics in wild-caught invertebrates, from bivalves in Oregon (Baechler, Granek, Hunter, & Conn, 2019) and southeastern India (Naidu, 2019), to deep-sea invertebrates in the northeast Atlantic (Courtene- Jones, Quinn, Ewins, Gary, & Narayanaswamy, 2019) and around the world (Jamieson et al, 2019), to coral reefs in the South China Sea (Ding et al, 2019), Australia (Jensen, Motti, Garm, Tonin, & Kroon, 2019), and cold-water corals off the coast of Scotland (La Beur et al, 2019). Wang, Wang, Ru, and Liu (2019) measured the abundance and characteristics of microplastics found in sediments and benthic organisms from the South Yellow Sea, China, and documented 1.7-47.0 particles per gram (ww).…”