Wednesday, August 4, 2010: 10:50 AM
320, David L Lawrence Convention Center
Background/Question/Methods The ability of species to disperse across the landscape helps them to cope with a changing environment. Processes like global warming can negatively affect a species’ current habitat, but simultaneously will create new suitable habitat elsewhere that can be colonized. However, only those species that are able to disperse to the new areas will endure. This seems especially challenging for species living in isolated wetlands, for which suitable habitat is distributed as patches in a matrix of land. Nevertheless, many freshwater wetlands have a high biodiversity which suggests regular dispersal, even of aquatic organisms that rely on passive transport vectors like wind, water, humans or animals.
The answer potentially lies in the highly abundant water birds in wetlands, as already suggested byDarwin in 1859. They can carry recently ingested seeds or aquatic invertebrates that survive digestion (endozoochory), or have propagules adhering to their outside (ectozoochory) on flights towards new suitable habitat.
Results/Conclusions We created and will present a taxonomical analysis of which aquatic organisms are currently known to be transported by (which) water birds. We identify gaps of knowledge and phylogenetic patterns of which species are actually dispersed and why. Furthermore, we noted that a surprisingly large amount of anecdotal evidence exists for the transport of aquatic snails by birds, but could not find actual evidence for bird mediated transport.
Therefore, we add our own experimental evidence for aquatic snails surviving passage through the digestive systems of birds, and their ability to adhere externally. Our experiments are also the first evidence that aquatic snails can be transported by water birds. Although at a low frequency, viable snails were retrieved up till five hours after being eaten, and snails stayed attached to the outside of birds even longer. Both endo- and ectozoochorous pathways provide snails with dispersal distances of over 200 kilometers. Differences between snail species in their suitability for transport by birds is also reflected in differences in their distributions, providing further evidence for this transport mechanism. We argue it is important to identify dispersal pathways like we did: Those aquatic species found to be transported by water birds in our taxonomic analyses will be less threatened by environmental pressures such as global warming then others, since they have a higher chance of flexibly colonizing new areas.
The answer potentially lies in the highly abundant water birds in wetlands, as already suggested by
Results/Conclusions We created and will present a taxonomical analysis of which aquatic organisms are currently known to be transported by (which) water birds. We identify gaps of knowledge and phylogenetic patterns of which species are actually dispersed and why. Furthermore, we noted that a surprisingly large amount of anecdotal evidence exists for the transport of aquatic snails by birds, but could not find actual evidence for bird mediated transport.
Therefore, we add our own experimental evidence for aquatic snails surviving passage through the digestive systems of birds, and their ability to adhere externally. Our experiments are also the first evidence that aquatic snails can be transported by water birds. Although at a low frequency, viable snails were retrieved up till five hours after being eaten, and snails stayed attached to the outside of birds even longer. Both endo- and ectozoochorous pathways provide snails with dispersal distances of over 200 kilometers. Differences between snail species in their suitability for transport by birds is also reflected in differences in their distributions, providing further evidence for this transport mechanism. We argue it is important to identify dispersal pathways like we did: Those aquatic species found to be transported by water birds in our taxonomic analyses will be less threatened by environmental pressures such as global warming then others, since they have a higher chance of flexibly colonizing new areas.