Biodiversity is directly related to the integrity of the ecosystem. The Pacific salmon requires several different ecosystems during
its life cycle. These would include the frershwater, the estuarine, and the marine ecosystems. Healthy ecosystens are made up of
diverse communities made up many different plants and animals that interact together in a complex web. For instance in the
freshwater system, the whole watershed influences the health of the stream. The plant diversity in the watershed and the riparian
zone have a strong effect on the amount of rainfall that reaches the stream. Large woody debris, that provides complexity and
structure to the strean channel, also is recruited from the plant community. This plant diversity is made up of agents of decay and
renewal that include bacteria, fungi, and nematodes to earthworms.
    All species from the smallest microbes to animals like the beaver have a strong impacts on the water quality and the health and
productivity of the freshwater ecosystem. Certain species are considered more important or critical to the functioning of the
ecosystem. These species are referred to as "keystone" species. The removal of a keystone species can have dire effects on the
health of the ecosystem and in some cases total collapse of the ecosystem is possible.
    The Pacific salmon in abundant numbers is a keystone species in the riverine habitat. The return of these fieh to the watershed
brings needed nutrients and food to many species of plants and animals. Scavengers and predators like eagles and bears depend
on this food sourse and the numbrs of returning fish has a direct correlation to the number of these animals present in the
ecosystem. The size of the returning salmon run also has a effect on the numbr of juvenile fish that can rear in a given stream. One
can only imagine what the changes in the diversity of the plants and animals have been in streams that have lost their salmon runs.
By comparing a healthy salmon stream to a stream that at one time lost its salmon run one should be able to see differences in the
biodinersity of the two streams and how they function.
    In the marine ane the estuarine ecosystems the salmon depends on diversity for its food and other species depend on the
salmon for their food sourse. One missing link in the food web could spell disaster for the ecosystem.
 

Jeff Heinis