Assessment of Contaminant Load and Its Relationship to Foraging in a Top Marine Predator

EPA Grant Number: F13C31180
Title: Assessment of Contaminant Load and Its Relationship to Foraging in a Top Marine Predator
Investigators: Gilmour, Morgan Elizabeth
Institution: University of California - Santa Cruz
EPA Project Officer: Lee, Sonja
Project Period: September 27, 2014 through September 27, 2016
Project Amount: $84,000
RFA: STAR Graduate Fellowships (2013) RFA Text |  Recipients Lists
Research Category: Academic Fellowships , Fellowship - Oceanography , Fellowship - Environmental Toxicology


This research will test the hypothesis that foraging strategies of frigate birds and boobies reflect seasonal fluctuations in available prey and local oceanographic conditions, resulting in colony-specific variations in contaminant loads and foraging behaviors. This hypothesis will be tested by (1) assessing the contaminant loads of heavy metals (such as mercury) and organochlorines (such as DDT and its metabolites) of several populations of two seabirds, boobies (Sula spp.) and frigatebirds (Fregata spp.); (2) identifying important foraging areas with GPS-tracking tags; and (3) relating the seabirds’ contaminant loads with their diets and regional foraging locations.


Contaminant loads in seabirds will be assessed by sampling blood from breeding seabirds in several colonies. The blood will be tested for mercury and such organochlorines as DDT; these contaminants affect breeding behaviors and also can be lethal to birds. The sampled seabirds will be fitted with GPS-tracking tags to record foraging trips as the birds search for fish at sea. These data will allow identification of important foraging areas to these birds and determination of important foraging behaviors and characteristics that may help explain how these birds find food. The contaminant and tracking data will be combined to estimate whether these foraging areas contain harmful contaminants for these seabirds, fish and humans.

Expected Results:

Mercury and organochlorines, such as DDT and PCBs, are highly volatile at low latitudes that exhibit warm temperatures. As warm air travels to cooler temperatures, the ocean becomes a sink for atmospheric organochlorines and mercury, and their concentrations increase with latitude. It is expected that (1) birds foraging in more northern areas that exhibit cooler sea-surface temperatures will exhibit higher contaminant loads than birds that forage in warmer waters; and that (2) due to anthropogenic uses of organochlorines and mercury in agriculture and industrial processes, birds that forage closer to coasts will exhibit higher contaminant loads than birds that forage further from human settlements.

Potential to Further Environmental/Human Health Protection

Boobies and frigatebirds typically eat sardines, anchovies and squid—the same fish eaten by both humans and many large sport fish, like tuna. Sampling contaminant loads in these birds will help to create an accurate picture of the types of contaminants that humans and commercially important fishes are exposed to in the oceanic environment. Information from this study can be used to create and support policy decisions for protected resources, risk assessment with fisheries operations and restoration of habitats.

Supplemental Keywords:

contaminants, mercury, organochlorines

Progress and Final Reports:

  • 2015
  • Final