Spatial variation and biovectoring of metals in gull faeces

Víctor Martín-Vélez,F Hortas,M.A Taggart,A.J Green,N.J Óhanlon,M.I Sánchez

doi:10.1016/j.ecolind.2021.107534

Víctor Martín-Vélez, F Hortas + Show 4 more

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https://doi.org/10.1016/j.ecolind.2021.107534

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Abstract

We assessed the spatial variation in concentrations of ten metals in faeces of the lesser black-backed gull (LBBG) Larus fuscus wintering at seven localities in South-West Spain. We found high concentrations of metals in gull faeces, with several elements (As, Cu, Mo, Pb, Zn) locally exceeding (by 2 to 11 times) derived Lowest Effect Level (LEL) values. We also found strong spatial variation, related to the main pollution sources associated with the different sites. Faeces from Chipiona Port (Gulf of Cádiz) showed the highest levels of As; Cetina saltpans (Bay of Cádiz) ranked first for Pb, Zn and Mo, which was consistent with historic mining and industrial pollution; Doñana ricefields showed the highest levels of Mn, a highly available element in flooded areas; while landfills ranked first for Cd, Co, Cr, Cu and Ni, potentially associated with electronic waste. Furthermore, we demonstrate how faecal analysis can be used to quantify biovectoring of metals into specific localities, using LBBG movement ecology and census data. At Fuente de Piedra, a shallow, closed-basin lake important for waterbirds, we show that metal inputs by LBBG have increased in recent years, and long-term deposition (e.g., of Pb) may impact aquatic communities and ecological processes in this Ramsar site.

Highlights

Anthropogenic activities are increasingly contributing to environmental pollution worldwide (Baby et al, 2010; Vareda et al, 2019)
We assessed the spatial variation in concentrations of ten metals in faeces of the lesser black-backed gull (LBBG) Larus fuscus wintering at seven localities in South-West Spain
We found strong spatial variation, related to the main pollution sources associated with the different sites

Summary

Introduction

Anthropogenic activities (e.g., industrial processes, urban and agri cultural practices) are increasingly contributing to environmental pollution worldwide (Baby et al, 2010; Vareda et al, 2019). Aquatic ecosystems are vulnerable because pollutants cause direct impacts in biota, resulting in lethal or sub lethal effects, and a variety of indirect perturbations through trophic cascades that can result in dramatic changes in food webs, ecosystem structure and nutrient fluxes (Fleeger et al, 2003; Baby et al, 2010). Understanding how toxic metals and metalloids enter and distribute within aquatic environments, and identifying potential sources of contamination in the environment, are critical points in evaluating the risks they pose to the environment, wildlife and human health. While pathways and entry routes of metals into aquatic ecosystems via abiotic (physical) mechanisms are well characterized, the role of biological transport has been widely overlooked (Blais et al, 2007). There exists increasing evidence of pollutant transport within and among ecosystems via biota (Michelutti et al, 2010), which can, in some cases, even exceed that mediated by

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