Ecological extinction
Estes, Duggins, and Rathburn (1989) recognize two other distinct types of extinction: Robert Paine (1969) first came up with the concept of a keystone species while studying the effects of the predatory sea star Pisaster ochraceus, on the abundance of the herbivorous gastropod, Tegula funebralis.
This study took place in the rocky intertidal habitat off the coast of Washington; Paine removed all Pisaster in 8m x 10m plots weekly while noting the response of Tegula for two years.
Historical over harvesting of sea otter furs has severely restricted their once wide-ranging habitat, and only today are scientists starting to see the implications of these local extinctions.
[3] The California spiny lobster, or Panulirus interruptus, is a keystone predator that has a distinct role in maintaining species diversity in its habitat.
Robles (1987) demonstrated experimentally that the exclusion of spiny lobsters from the intertidal zone habitats led to the competitive dominance of mussels (Mytilus edulis and M. californianus).
These algal blooms have competitively excluded any other species from surviving, including the rich diversity in faunal life that once flourished such as dolphins, manatees, river otters, sea turtles, alligators, sharks, and rays.
[5] The potential ecological extinction of guanacos (Lama guanicoe) and lesser rheas (Pterocnemia pennata) as a prey source for native omnivores and predators in the Argentine Patagonia was assessed by a study by Novaro in 2000.
This was the first study to take into account a large number of diverse predators, ranging from skunks to pumas, as well as conduct their survey in non-protected areas that represent the majority of southern South America.
The effect of introduction of new competitors, such as the red deer and rabbit, also served to alter the vegetation in the habitat, which could have further pronounced the intensity of competition.
Novaro and his colleagues suggest "this loss could have strong effects on plant-animal interactions, nutrient dynamics, and disturbance regimes ..."[6] This is an example of how current conservation policy has failed to protect the intended species because of its lack of a functionally sound definition for extinction.
Ants disperse up to 30% of the flora in the shrublands and are vital to the survival of fynbos plants because they bury the large seeds away from the dangers of predation and fire damage.
As hypothesized, McConkey and Drake found a threshold relationship between the Flying Fox Index (FFI) and the median proportion of seeds carried over five meters.
[8] While ecologists are just starting to get a grapple on the significant interactions within an ecosystem, they must continue to find an effective density threshold that can maintain the level of equilibrium species diversity.
[11] Conservation policy has historically lagged behind current science all over the world, but at this critical juncture politicians must make the effort to catch up before massive extinctions occur on our planet.
It is now that the governments of the world must act in order to prevent this catastrophe of the loss of biodiversity from progressing further and wasting all of the time and money spent on previous conservation efforts.
