Monitoring of mercury in the mesopelagic domain of the Pacific and Atlantic oceans using body feathers of Bulwer's petrel as a bioindicator

Abstract

Bulwer's petrels were used as biomonitors of Hg levels in the mesopelagic domain.• Atlantic colonies showed higher Hg concentrations than those from the Pacific. • CSIA-AA-derived trophic levels for chicks were similar among colonies. • Feather Hg levels recorded were lower than those reported in 1992 for the Atlantic.

Revealing the foraging movements and diet of the White-faced Storm Petrel Pelagodroma marina in the NE Atlantic

“…The chicks of White-faced Storm Petrel showed no significant differences in mercury concentration in body feathers compared to the chicks of Bulwer's Petrel, a specialist predator of mesopelagic prey (Waap et al 2017) from the Deserta Grande, Madeira (275 km north of our study site), that showed a mercury concentration in body feathers of 4.38 ± 1.69 mg kg −1 dw in 2018 (mean ± SE, Furtado et al 2021) (Welch's t test, t = − 1.491, df = 0.28, P = 0.148). Seabirds feeding on mesopelagic prey present higher mercury concentrations in feathers than those feeding predominantly on epipelagic prey (Monteiro and Furness 1995;Kim et al 1996;Monteiro et al 1996;Bond and Diamond 2009;Carravieri et al 2018;Furtado et al 2019Furtado et al , 2021. Hence, mercury measurements in feathers support the idea that White-faced Storm Petrels raise their chicks mostly on mesopelagic prey.…”

“…Feathers were clipped at the superior umbilicus of the feather, excluding the calamus, and stored in polyethylene bags. Samples were weighed on a Sartorius M5P micro balance (Sartorius AG, Goettingen) (mass between 0.441 and 3.020 mg, mean 1.23 ± 0.59 mg) and analysed according to the method described in Furtado et al (2021). Total mercury in the body feathers was quantified by atomic absorption spectrophotometry with thermal decomposition (Costley et al 2000) in LECO AMA-254 with a detection limit of 0.01 ng of mercury.…”

“…Seabirds that rely extensively on mesopelagic prey tend to display high mercury concentrations compared to species with an epipelagic diet (e.g., Carravieri et al 2018;Furtado et al 2019Furtado et al , 2021Monteiro and Furness 1995;Kim et al 1996). This is due to the higher rate of microbial-mediated methylation of mercury in sub-thermocline low oxygen waters (Choy et al 2009).…”

“…We also briefly describe the prey delivered during chick rearing by examining chick faecal samples using DNA metabarcoding. In addition, we report the mercury levels in chick body feathers in Selvagem Grande, reflecting the concentration of this heavy metal in prey obtained in the foraging areas used during chick rearing (Stewart et al 1997;Furtado et al 2021).…”

Pan-oceanic distribution of mercury (Hg) in sea turtles: a review

“…Other marine organisms such as sea birds have also been shown to reflect regional characteristics on Hg levels. Comparing 2 colonies of Bulwer's petrel Bulweria bulwerii between the Atlantic and the Pacific showed that chicks and adults had significantly higher concentrations of Hg in the colonies of the Atlantic than those of the Pacific Ocean (Furtado et al 2021). Given that this species has no apparent trophic differences, the most likely explanation is that food items consumed by these birds (e.g.…”