Porphyrin levels in excreta of sea birds of the Chilean coasts as nondestructive biomarker of exposure to environmental pollutants.

In this preliminary study on sea birds we propose the use of porphyrins in excreta as a biomarker of exposure to contaminants. Samples of excreta were obtained from colonies of brown pelicans (Pelecanus occidentalis thagus), neotropic cormorants (Phalacrocorax olivaceus), and kelp gulls (Larus dominicanus) in three areas of the south coast of Chile with different human impact (Tubul, Talcahuano, and Valdivia). They were analyzed for porphyrin content (copro-, uro-, and protoporphyrins and total porphyrins) by a rapid fluorimetric method and by HPLC. The main outcomes of the study were: (a) kelp gulls and neotropic cormorants living in areas with high human impact showed a clear capacity to accumulate and eliminate porphyrins in the excreta; (b) species-related accumulation capacities are likely, as shown by the different levels found in different species living in the same area; (c) the porphyrin profile obtained by fluorimetry and HPLC showed a higher percentage of protoporphyrin than the other porphyrins; (d) although the fluorimetric method of Grandchamp is semiquantitative, it was found to be sensitive enough to detect differences in samples from field studies. The positive results of this preliminary study make it possible to propose this nondestructive method for a variety of field applications.