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Many of the causes of amphibian declines are well understood, and appear to affect other groups of organisms as well as amphibians. These causes include habitat modification and fragmentation, introduced predators or competitors, introduced species, pollution, pesticide use, or over-harvesting. However, many amphibian declines or extinctions ...
Additionally, 1193 amphibian species (16.4% of those evaluated) are listed as data deficient, meaning there is insufficient information for a full assessment of conservation status. As these species typically have small distributions and/or populations, they are intrinsically likely to be threatened, according to the IUCN. [ 3 ]
Causes of habitat fragmentation include geological processes that slowly alter the layout of the physical environment [36] (suspected of being one of the major causes of speciation [36]), and human activity such as land conversion, which can alter the environment much faster and causes the extinction of many species.
The release of nitrogen oxides (N 2 O, NO) from anthropogenic activities and oxygen-depleted zones causes stratospheric ozone depletion leading to higher UVB exposition, which produces the damage of marine life, acid rain and ocean warming. Ocean warming causes water stratification, deoxygenation, and the formation of dead zones.
The decline in amphibian and reptile populations has led to an awareness of the effects of pesticides on reptiles and amphibians. [176] In the past, the argument that amphibians or reptiles were more susceptible to any chemical contamination than any land aquatic vertebrate was not supported by research until recently. [ 176 ]
If toxicity is the cause, species are more generally affected and the event may include amphibians and shellfish as well. A reduction in dissolved oxygen may affect larger specimens more than smaller fish as these may be able to access oxygen richer water at the surface, at least for a short time.
Many physical processes over ocean surface generate sea salt aerosols. One common cause is the bursting of air bubbles, which are entrained by the wind stress during the whitecap formation. Another is tearing of drops from wave tops. [19] The total sea salt flux from the ocean to the atmosphere is about 3300 Tg (3.3 billion tonnes) per year. [20]
With primary causes being warming ocean waters, ocean acidity, and pollution. [3] In 2008, a worldwide study estimated that 19% of the existing area of coral reefs had already been lost. [ 4 ] Only 46% of the world's reefs could be currently regarded as in good health [ 4 ] and about 60% of the world's reefs may be at risk due to destructive ...