Species Diversity Within and Among Ecosystems - Ecological Systems - page 260

currently threatened with extinction; areas with particularly high densities of
threatened bird species are the tropical Andes, the Atlantic forests of Brazil,
the Eastern Himalayas, Eastern Madagascar, and the archipelagos of Southeast
Asia [ 38 , 44 ].
The LPI shows an overall decline of 8% for birds and 28% for tropical birds
alone. The main threats to birds are the spread of logging, wood harvesting, and
agriculture in addition to the impacts of invasive alien species. Residential and
commercial development, hunting, and pollution are also having serious impacts on
bird populations globally [ 38 , 44 ].
Amphibians
As amphibians are dependent on water for reproduction and other stages of their life
cycles, the majority are found in tropical moist forests or freshwater ecosystems.
Amphibian species richness is highest in the Neotropical regions of South and
Central America and the countries with the highest species richness are Brazil,
Colombia, Ecuador, and Peru. The Southeastern USA also has high species richness
due to the large number of native salamander species. Roughly 30-56% of all
amphibian species are currently threatened with extinction [ 45 ]. Among
vertebrates, they have the highest proportion of Critically Endangered species and
highest number of recent extinctions. The highest species richness of threatened
amphibians is found in the dense tropical and subtropical forests of the Northern
Andes, Caribbean, Western Ghats, Malaysian Borneo, and West Africa [ 38 , 45 ].
There is only limited data on amphibian population trends, so the LPI result of an
80% decline should be treated with caution [ 38 ]. There is, however, a great deal of
supporting evidence that amphibian species have suffered a major decline since the
1970s [ 40 , 45 , 49 , 50 ]. Their aquatic habitats are under great human pressures,
which included rapid deforestation, habitat degradation, pollution, and overuse of
water. In addition, the emergence of the chytrid fungus, Batrachochytrium
dendrobatidis , is another major threat. First described in the 1990s, the fungus is
now found on every continent inhabited by amphibians and evidence suggests that
it is responsible for causing mass mortalities among many populations [ 51 , 52 ].
Fishes
The West and Central Indo-Pacific, South China, and Coral Sea are the areas of the
highest marine fish species richness, while Southeast Asia, Eastern Africa's Great
Lakes, South American Amazonia, and the forest of Central Africa have the highest
species richness of freshwater fish [ 38 ]. Of the world's fish species, 41% are
obligate freshwater, 58% are obligate marine, and the remaining 1% can tolerate
both systems. An assessment of a representative sample of fish species suggests that