The Use of Novel Biomarkers in Waterbird Biology

The use of focal species in determining the condition of a particular habitat type is a growing trend in conservation and management. In coastal-marine environments, bioindicators have been identified as the most ecologically relevant focal species for guiding coastal estuary monitoring programs. Colonial waterbirds have long been used as bioindicators due to their intimate connection with the hydrologic regime, high trophic position, and central place foraging at breeding locations. Population-level observations are frequently used for monitoring the health of near-shore habitats utilized by waterbirds, however these data are often limited to indicating that change has taken place and lend little predictive power to causality. Individual-level biomarkers serve as more useful tools for identifying the proximate factors leading to population-level fluctuations. Attributes of the individual that can accurately represent the threat associated with change are useful bioindicator tools and, when coupled with population-level data, prove useful for ecosystem monitoring. In this dissertation I investigate resource use by breeding adult waterbirds and introduce and apply novel biomarkers of contaminant stress. These biomarkers are easy to collect, serve as efficient predictors of large-scale processes, and are cost effective. I use developmental instability (DI) and ptilochronology to determine the nutritional health of nestling waterbirds in locations of drastically different environmental qualities. When coupled with observations of diet, mercury load and nestsite interactions, these biomarkers accurately reflect local foraging habitat health and further strengthen the use of waterbirds as potential bioindicators of coastal estuary condition.

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