Tropical seabirds sample broadscale patterns of marine contaminants

M E Gilmour; S A Trefry Hudson; C Lamborg; A B Fleishman; H S Young; S A Shaffer

doi:10.1016/j.scitotenv.2019.07.147

Tropical seabirds sample broadscale patterns of marine contaminants

Sci Total Environ. 2019 Nov 15:691:631-643. doi: 10.1016/j.scitotenv.2019.07.147. Epub 2019 Jul 12.

Authors

M E Gilmour¹, S A Trefry Hudson², C Lamborg³, A B Fleishman⁴, H S Young⁵, S A Shaffer⁶

Affiliations

¹ Ocean Sciences Department, University of California, Santa Cruz, CA 95060, USA. Electronic address: mgilmour@ucsc.edu.
² Department of Biology, University of New Brunswick, Fredericton, New Brunswick E3B 5A3, Canada.
³ Ocean Sciences Department, University of California, Santa Cruz, CA 95060, USA.
⁴ Department of Biological Sciences, San Jose State University, San Jose, CA 95192, USA; Conservation Metrics, Inc., 145 McAllister Way, Santa Cruz, CA 95060, USA.
⁵ Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA 93106, USA.
⁶ Department of Biological Sciences, San Jose State University, San Jose, CA 95192, USA.

PMID: 31325863
DOI: 10.1016/j.scitotenv.2019.07.147

Abstract

Contaminants in the marine environment are widespread, but ship-based sampling routines are much narrower. We evaluated the utility of seabirds, highly-mobile marine predators, as broad samplers of contaminants throughout three tropical ocean regions. Our aim was to fill a knowledge gap in the distributions of, and processes that contribute to, tropical marine contaminants; and explore how species-specific foraging ecologies could inform or bias our understanding of contaminant distributions. Mercury and persistent organic pollutant (POPs) concentrations were measured in adults of five seabird species from four colonies in the central Pacific (Laysan and Tern Islands, Hawaii; Palmyra Atoll) and the eastern Caribbean (Barbuda). Blood-based total mercury (THg) and 89 POPs were measured in two seabird families: surface-foraging frigatebirds (Fregata spp.) and plunge-diving boobies (Sula spp.). Overall, largescale contaminant differences between colonies were more informative of contaminant distributions than inter-specific foraging ecology. Model selection results indicated that proximity to human populations was the best predictor of THg and POPs. Regional differences in contaminants were distinct: Barbudan Magnificent Frigatebirds had more compounds (n=52/89 POP detected) and higher concentrations (geometric mean THg=0.97μgg^-1; mean ΣPOP₅₃=26.6ngmL^-1) than the remote colonies (34-42/89 POP detected; range of THg geometric means=0.33-0.93μgg^-1; range of mean ΣPOP₅₃:7.3-17.0ngmL^-1) and had the most recently-synthesized POPs. Moderate differences in foraging ecologies were somewhat informative of inter-specific differences in contaminant types and concentrations between nearshore and offshore foragers. Across species, contaminant concentrations were higher in frigatebirds (THg=0.87μgg^-1; ΣPOP₅₃=17.5ngmL^-1) compared to boobies (THg=0.48μgg^-1; ΣPOP₅₃=9.8). Ocean currents and contaminants' physiochemical properties provided additional insight into the scales of spatial and temporal contaminant exposure. Seabirds are excellent, broad samplers with which we can understand contaminant distributions in the marine environment. This is especially important for tropical remote regions that are under-sampled.

Keywords: Foraging ecology; Fregatidae; Mercury; Persistent organic pollutants; Spatial ecotoxicology; Sulidae.

MeSH terms

Animals
Birds / metabolism*
Environmental Monitoring*
Environmental Pollutants / analysis
Environmental Pollutants / metabolism*
Environmental Pollution / statistics & numerical data*
Mercury / analysis

Substances

Environmental Pollutants
Mercury