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In Central-Eastern Argentina, a 2017 study found large quantities of metal pollutants (chromium, copper, arsenic and lead) in their freshwater streams, disrupting the aquatic biota. [183] The level of chromium in the freshwater systems exceeded 181.5× the recommended guidelines necessary for survival of aquatic life, while lead was 41.6× ...
The researchers examined around 23,500 species of dragonflies, fish, crabs and other animals that depend exclusively on freshwater ecosystems. They found that 24% were at risk of extinction – classified as vulnerable, endangered or critically endangered – due to compounding threats from pollution, dams, water extraction, agriculture ...
Aquatic animals (especially freshwater animals) are often of special concern to conservationists because of the fragility of their environments. Aquatic animals are subject to pressure from overfishing/hunting, destructive fishing, water pollution, acidification, climate change and competition from invasive species.
The culture that has been connected with the wave of extinctions in North America is the paleo-American culture associated with the Clovis people (q.v.), who were thought to use spear throwers to kill large animals. The chief criticism of the "prehistoric overkill hypothesis" has been that the human population at the time was too small and/or ...
Every species of freshwater crab described so far has been assessed by the International Union for Conservation of Nature; [6] of the species for which data are available, 32% are threatened with extinction. [5] For instance, all but one of Sri Lanka's 50 freshwater crab species are endemic to that country, and more than half are critically ...
Large body size is generally associated with other traits, such as having a slow rate of reproduction and, in large herbivores, reduced or negligible adult mortality from being killed by predators. Megafauna species have considerable effects on their local environment, including the suppression of the growth of woody vegetation and a consequent ...
The invasive freshwater zebra mussels, native to the Black, Caspian, and Azov seas, were probably transported to the Great Lakes via ballast water from a transoceanic vessel. [21] Meinesz believes that one of the worst cases of a single invasive species causing harm to an ecosystem can be attributed to a seemingly harmless jellyfish.
Invasive species are defined by the U.S. Department of Agriculture as non-native to the specific ecosystem, and whose presence is likely to harm the health of humans or the animals in said system. [140] Introductions of non-native species into new areas have brought about major and permanent changes to the environment over large areas.