About this Research Topic
What is generally known about the Amazonian ecosystem is that it is very large, contains high biodiversity, and is endangered. The ecosystem is a continuum between aquatic and terrestrial biotic communities that interact with and depend upon each other. The Amazon River Basin covers more than a million km2, and produces about 18% of the earth's river water discharge. The region is the home of more fish species than anywhere else on Earth. The high biodiversity of this system is largely a result of the complexity of the physical environment, including seasonal variations in water depth (ca. 15 meters difference between high and low water seasons) and the isolation of lakes upon the floodplains at low water. These and other factors operating over geological time have promoted adaptive radiation into a wide variety of local environments within this vast system, providing opportunities for specialization and speciation. Floodplains are important ecotones where the interaction between terrestrial and aquatic components of the ecosystem are most clearly evident, and therefore where our research is concentrated.
Many of the threats to biodiversity in this system are shared by tropical wet forests in general, such as deforestation, invasive species introductions, and droughts caused by climate change. The majority of publications on tropical ecosystems concern the terrestrial component, especially with regard to deforestation. Reduction of the floodplain forest component also has profound effects on the aquatic environment, including loss of allochthonous sources of food for aquatic animals. Similarly, damming rivers can reduce nutrient supply to the forest as well as interrupt dispersal of terrestrial plant seeds (ichthyochory). Dams also disrupt migratory species, play havoc with metapopulation dynamics, alter hydrologic and sedimentary conditions, and increase the risk of mercury contamination. An increasing number of smaller dams built to impound alien fish (tilapia) for aquaculture have both altered hydrology and enabled these invasive species to escape and threaten native fish populations. In addition, overfishing by both resident human communities and commercial enterprises that sell the catch elsewhere have changed the structure of natural fish assemblages. Finally, water contamination all along the Amazon River system from the Andes to the Atlantic estuary that are linked to agriculture, gold mining, and industrial wastes, also are of concern.
The challenges for science in the Amazon River Basin are to:
(1) identify patterns of distribution and abundance of species that can indicate important ecological interactions, such as competition, predation, symbiosis, etc;
(2) discern the environmental correlates, including landscape components, with these patterns that give clues to the evolution of biodiversity and development of biotic communities;
(3) use our knowledge of why these systems are biodiverse to preserve species assemblages through intelligent conservation measures.
We propose to solicit papers for our collection based on their relevance to these three issues, specifically associated with floodplain ecosystems. Many of the papers will be concerned with the aquatic environment, but we also wish to include papers on terrestrial organisms in the region, especially those that illustrate how the terrestrial and aquatic environments are interconnected.
Keywords: Amazon Basin, Biodiversity, Tropical Ecosystems, Floodplain Ecology, Diversity Evolution
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