Micronuclei in embryos of eight seabird species in northwestern Mexico: A biomarker of exposure to coastal pollution?

The micronucleus (MN) test may be used to evaluate genome instability in birds and the potential of different species to function as biomarkers of genotoxicity. However, little is known regarding genome instability in seabird embryos or the instability present among embryonic development stages. Therefore, the present study aimed to describe the frequencies of micronucleated erythrocytes (MNE) and micronucleated polychromatic erythrocytes (MNPCE) in blood samples collected from the embryos of eight seabird species nesting on the coast of Sinaloa, Mexico. An additional description of blood cell maturation along with embryo development during incubation was conducted based on the proportion of polychromatic erythrocytes (PCE), and the potential relationships between metals (Hg and Cd concentrations in egg content) and the MN frequencies in embryo blood were evaluated. The PCE proportion appears to decline as incubation advances (initial stage > intermediate stage > advanced stage), and the values varied between species (Suliformes/Pelecaniformes < Charadriiformes: Laridae), which may be related to differences among incubation periods and reproductive strategies. Interspecific variation in the MNPCE frequency was found in embryos showing advanced development, which could be related to both variations in life-history traits and ecological factors and not Hg or Cd exposure. The genomic instability values in this study are the first to be reported for embryos of seabird species nesting in a subtropical coastal region.

Temporal and sex-based variation in organochlorine pesticide levels in the blue-footed booby in two coastal colonies of Sinaloa, Mexico.

The temporal, inter-site, and sex-based variation of 19 organochlorine pesticides (OCPs) in blood plasma samples collected from blue-footed boobies of two islands in Sinaloa, Mexico, was evaluated. The effect of OCPs was evaluated with the heterophil/lymphocyte ratio, micronucleated erythrocyte frequency, and scaled mass index. The OCP-group levels decreased as the breeding season progressed, and interannual (but not inter-colony) differences were detected. Intra-annual variation in OCP levels seemed to reflect run-off inputs, although other environmental processes may better explain the variation between years. Sex-based differences in OCP levels were likely related to ecological and physiological processes linked to breeding (e.g., egg-laying and use of lipid reserves). No correlations between OCP-group levels and biomarkers were detected. Small pelagic fishes are the main prey sources of blue-footed boobies and the targets of regional industrial fisheries, and thus blue-footed booby OCP levels could reflect ecosystem health and indicate potential risks for human consumers.