Mercury, viruses and seabirds of French Guiana

The multidisciplinary SENTINEL project aims to:

1) establish the state of the art on contaminants (mercury, persistent organic pollutants, poly- and perfluorinated compounds) present in seabirds in French Guiana,
2) interpret the levels observed via trophic ecology
3) estimate the effects on physiology, immunity and reproduction. These toxicological data are essential to monitor, via these sentinels, the overall state of health of the French Guiana coastline.

In the Grand-Connétable Nature Reserve

This programme is carried out in the Grand-Connétable Island Nature Reserve, the only functional marine protected area on the Amazonian coast and the second largest marine nature reserve overseas. Six species of seabirds nest in this reserve : Superb frigatebird, Black-headed Gull, Royal Tern, Cayenne Tern, Sooty Tern and Brown Noddy. The Nature Reserve covers 7,852 hectares and is managed by the Groupe d’Étude et de Protection des Oiseaux en Guyane (GEPOG).

Bioanalysis at the centre of the program

SENTINEL is based on the skills of the CEBC’s biological analysis service, and involves numerous research laboratories (CEBC, National Museum of Natural History, Paris, LIENSs, University of La Rochelle, Pasteur Institute and University of Antwerp).

High mercury contamination

The SENTINEL program focuses on the mercury contamination of several species of seabirds nesting in the Great Constable Nature Reserve. Indeed, French Guiana is characterised by old soils whose mercury concentrations are on average 5 times higher than those of temperate soils, and by a gold mining activity using this element for gold extraction, an activity that has released several hundred tonnes of this metal into the environment since the beginning of the 20th century. Stable isotopes (C and N) are also measured in order to place the search for contaminants in a trophic ecology context. Adults and chicks of six species of seabirds were sampled.


The results show high mercury contamination for the seabird community of the Great Constable, particularly for the superb frigates. This contamination is more pronounced in adults and in species at a high trophic level. In frigate birds and gulls, mercury levels are of concern and are likely to affect the health of individuals. Measurements of historical persistent organic pollutants (POPs) have also been carried out and show low levels of contamination, much lower than those found in polar birds (Arctic, TAAF).

Massive mortality in frigate chicks and herpes viruses

In collaboration with the Pasteur Institute, the SENTINEL program has been looking at the mechanisms involved in the mass mortalities seen in frigate chicks. The disease is characterized by the appearance of visible clinical signs (skin crusts) that spread rapidly throughout the body, progressive weakening and, in the vast majority of cases, death of the chick. This disease is associated with a herpes virus, which is specific to super frigate birds.

Does mercury promote disease states in these birds?

The prevalence of high mercury levels and disease outbreaks has prompted us to continue our research studying the oxidative status of chicks, showing that oxidative stress is associated with the onset of clinical signs. Given that mercury can disrupt the regulation of oxidation, it is questionable whether mercury promotes disease states in these seabirds. We therefore verified whether the disease is associated with (i) food shortage and (ii) mercury exposure. Our experience with feed supplementation has shown that chicks that have received feed are protected against the appearance of clinical signs and show an increased ability to recover from the disease. In contrast, experimental supplementation with selenium, a trace element known to protect against the adverse effects of mercury, did not improve clinical signs, but supplemented birds showed interesting physiological trends. A potential synergistic or additive interaction between food availability and mercury exposure in determining recurrent episodes of disease makes this project unique, and the SENTINEL project has opened the door to various collaborations and other projects to investigate this topic further.

ECOPHY team: The SENTINEL programme is supported by the DEAL Guyana and the CNRS Researchers involved: Manrico Sebastiano and Olivier Chastel (CEBC), David Costantini (MNHM), Marcel Eens (University of Antwerp)