Abstract
Marine plastic pollution is increasing exponentially, impacting an expanding number of taxa each year across all trophic levels. Of all bird groups, seabirds display the highest plastic ingestion rates and are regarded as sentinels of pollution within their foraging regions. The consumption of plastic contributes to sub-lethal impacts (i.e. morbidity, starvation) in a handful of species. Additional data on these sub-lethal effects are needed urgently to better understand the scope and severity of the plastics issue. Here we explore the application of fatty acid (FA) analysis as a novel tool to investigate sub-lethal impacts of plastic ingestion on seabird body condition and health. Using gas chromatography-mass spectrometry, we identified 37 individual FAs within the adipose, breast muscle and liver of flesh-footed (Ardenna carneipes) and short-tailed (Ardenna tenuirostris) shearwaters. We found high amounts of FA 16:0, 18:0, 20:5n3 (eicosapentaenoic acid), 22:6n3 (docosahexaenoic acid) and 18:1n9 in both species; however, the overall FA composition of the two species differed significantly. In flesh-footed shearwaters, high amounts of saturated and mono-unsaturated FAs (needed for fast and slow release energy, respectively) in the adipose and muscle tissues were related to greater bird body mass. While total FAs were not related to the amount of plastic ingested in either species, these data are a valuable contribution to the limited literature on FAs in seabirds. We encourage studies to explore other analytical tools to detect these sub-lethal impacts of plastic.
Highlights
Barnes et al, 2009, Provencher et al, 2017)
Palmitic acid (16:0) is the most abundant fatty acids (FAs) found in animals, and is commonly the product of de novo synthesis of 14carbon FAs within the liver of seabirds (Käkelä et al, 2009)
The abundance of this FA is believed to be important for the release of energy during migration, as observed in songbirds (McWilliams et al, 2004) and may explain why it is found in such high levels in fledgling shearwaters
Summary
Barnes et al, 2009, Provencher et al, 2017). Plastic can be readily consumed by a range of marine life from krill (Dawson et al, 2018) to large marine mammals (Fossi et al, 2018, Nelms et al, 2018). Different FAs serve different metabolic functions in animals and most FAs are combined into a range of lipid classes These include triglycerides (TAG), which are key to the storage of energy, phospholipids, which comprise the structural components of cell membranes, or wax esters, which are stored in various tissue structures (Ramos and Gonzalez-Solis, 2012). Adipose deposition has been scored and compared to morphometric measurements to determine body condition (Auman et al, 1997, Cousin et al, 2015, Schultner et al, 2013) Application of these methods to seabirds has received criticism as some measures of condition are thought to be subjective (van Franeker, 2004). We investigate the relationship between FA composition, linear morphometric measurements and plastic ingestion in two species of pelagic seabird: flesh-footed shearwaters (Ardenna carneipes) and short-tailed shearwaters (Ardenna tenuirostris) to better understand the potential sublethal impacts of ingested plastic
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