PEARL Paleoecological Environmental Assessment and Research Laboratory
Department of Biology, Queen's University, Kingston ON, Canada, K7L 3N6
Bird Biovector Studies
Birds often form large breeding colonies or roosts that can number in the tens of thousands. Because many species feed almost exclusively in the ocean, but nest on land, seabirds act as potent biological vectors of nutrients from marine to terrestrial ecosystems. The wastes released from seabird colonies provide critical nutrient subsidies for many coastal ecosystems, often creating thriving biological communities that would not exist otherwise. An unfortunate irony is that this transport pathway also concentrates contaminants that are biomagnified and bioaccumulated through the marine foodweb, thereby threatening the very ecosystem it supports and sustains. The biological transport of contaminants by seabirds is of global concern as they are the dominant form of wildlife along coastlines worldwide.
Sediment cores from lakes and ponds that drain seabird nesting sites can be used to track past seabird inputs over long-term timescales. This is a relatively new application of paleolimnology, the science that deals with reconstructing past ecological and environmental conditions using the physical, chemical, and biological information stored in sedimentary profiles. Lake and pond sediments archive a wealth of information about past seabird population dynamics (a rare commodity in most regions), and can be used to better understand the fate and transport of environmental contaminants. We track seabird inputs through time by analyzing sediment cores for: (1) stable isotopes of nitrogen (δ15N), which reflect foodweb dynamics and trophic structure and can also be used to track marine-derived nutrients; (2) the remains of biological indicators such as algae and aquatic invertebrates, which change in response to past nutrient and/or contaminant inputs; (3) fossil pigment such as chlorophyll a, which reflects past aquatic production; and (4) contaminants, such as persistent organic pollutants (POPs) and metals, which we can link to past seabird inputs.
Sediment cores from lakes and ponds located near large bird colonies can be used in paleoecological investigations because the seabird inputs have direct effects on downstream water chemistry, biological communities, and sediment geochemistry. In some instances, the actual bird guano deposits can be used as the environmental archive, much in the same way as sediment cores. For example, guano deposits can build up over time at the base of nesting or roosting sites. These deposits create natural archives that can be sampled and analyzed for changes in diet via insect remains, as well as environmental contaminants through time. Chimney swifts are one such species that leave deposits of guano and egested pellets that archive a record of diet and environmental contaminants.
The Paleoecological Environmental Assessment and Research Laboratory (PEARL), in collaboration with colleagues at the University of Ottawa, University of Alberta, and the Canadian Wildlife Service of Environment Canada, have been developing and applying some of these approaches to studying bird populations from different regions. Follow the links below for details and publications on each project.
Click on each bird image below to link to a web page with publications from these studies.
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Cape Vera |
Tern Island |
Chimney Swift |
