Microplastic Contamination Has Limited Effects on Coral Fertilisation and Larvae

Kathryn L E Berry,Nora M Hall,Hannah E Epstein,Phoebe J Lewis,Andrew P Negri

doi:10.3390/d11120228

Abstract

Microplastics are ubiquitous throughout the world’s oceans and contaminate coral reef ecosystems. There is evidence of microplastic ingestion by corals and passive contact with coral tissues, causing adverse health effects that include energy expenditure for particle removal from the tissue surface, as well as reduced growth, tissue bleaching, and necrosis. Here, it was examined whether microplastic contamination impairs the success of gamete fertilisation, embryo development and larval settlement of the reef-building coral Acropora tenuis. Coral gametes and larvae were exposed to fifteen microplastic treatments using two types of plastic: (1) weathered polypropylene particles and (2) spherical polyethylene microbeads. The treatments ranged from five to 50 polypropylene pieces L−1 and 25 to 200 microbeads L−1. Fertilisation was only negatively affected by the largest weathered microplastics (2 mm2), but the effects were not dose dependent. Embryo development and larval settlement were not significantly impacted by either microplastic type. The study shows that moderate–high levels of marine microplastic contamination, specifically particles <2 mm2, will not substantially interfere with the success of critical early life coral processes.

Highlights

The amount of plastic pollution entering the marine environment is increasing [1] concurrent to plastic production (384 million Mt in 2017 alone [2,3]) and global microplastic contamination was recently estimated at between five and 51 × 1012 particles [4,5]
Microplastics, which refer to plastic pieces
The effects of microplastics on fertilization and larval settlement were tested using gametes and larvae from six Acropora tenuis colonies collected at Magnetic Island (19.198578◦ S, 146.791696◦ E) 3 days prior to the November 2015 full moon to coincide with the 2015 mass spawning event on the Great

Summary

Introduction

The amount of plastic pollution entering the marine environment is increasing [1] concurrent to plastic production (384 million Mt in 2017 alone [2,3]) and global microplastic contamination was recently estimated at between five and 51 × 1012 particles [4,5]. 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. Fewer experiments have been conducted on Cnidaria [13,31,38,41,42,43], despite the documentation of microplastics in coral reef environments and organisms, including in north and central Australia, Mo’orea, and Hong Kong [13,14,15,44]

Methods

Results

Conclusion