Foraging guilds of aquatic birds on productive boreal lakes: environmental relations and concordance patterns |
| |
Authors: | Cynthia A Paszkowski William M Tonn |
| |
Institution: | (1) IMAR- Institute of Marine Research, Department of Zoology, Faculty of Sciences and Technology, University of Coimbra, 3004-517 Coimbra, Portugal;(2) Chesapeake Biological Laboratory, Center for Environmental and Estuarine Studies, University of Maryland, Solomons, Maryland 20688-0038, USA |
| |
Abstract: | Previous studies have shown that when an ecosystem consists of many interacting components it becomes impossible to understand
how it functions by focussing only on individual relationships. Alternatively, one can attempt to quantify system behaviour
as a whole by developing ecological indicators that combine numerous environmental factors into a single value. One such holistic
measure, called the system ‘ascendency’, arises from the analysis of networks of trophic exchanges. It deals with the joint
quantification of overall system activity with the organisation of the component processes and can be used specifically to
identify the occurrence of eutrophication. System ascendency analyses were applied to data over a gradient of eutrophication
in a well documented small temperate intertidal estuary. Three areas were compared along the gradient, respectively, non eutrophic,
intermediate eutrophic, and strongly eutrophic. Values of other measures related to the ascendency, such as the total system
throughput, development capacity, and average mutual information, as well as the ascendency itself, were clearly higher in
the non-eutrophic area. When the whole-system properties of the three areas were compared, however, the values associated
with the intermediate eutrophic area turned out to be the lowest, which possibly could be attributed to the unstable nature
of this area. The current study provided an example of how the measures arising out of␣network analysis might lead to an improved
understanding of the system functioning and of the eutrophication process itself. |
| |
Keywords: | network analysis ascendency eutrophication estuary |
本文献已被 SpringerLink 等数据库收录! |
|