Filed under: Nature | Tags: Africa, Animals, Black Rhino, Endangered, extinct, Extinction, International Rhino Foundation, mammals, Rhinoceros, species, Suman, WWF, zoo
An endangered species is a population of an organism (usually a taxonomic species), which because it is either few in number or threatened by changing environmental or predation parameters, leaving it at risk of becoming extinct. Many countries have laws offering special protection to these species or their habitats: for example, forbidding hunting, restricting land development or creating preserves.
Only a few of the many endangered species actually make it to the official lists and obtain legal protection.
Many more species become extinct, or potentially will become extinct, without gaining public notice. The greatest factor of concern is the rate at which species are becoming extinct within the last 150 years.
While species have evolved and become extinct on a regular basis for the last several hundred million years, the number of species becoming extinct since the Industrial Revolution has no precedent in biological history. If this rate of extinction continues, or accelerates as now seems to be the case, the number of species becoming extinct in the next decade could number in the millions.
While most people readily relate to endangerment of large mammals or birdlife, some of the greatest ecological issues are the threats to stability of whole ecosystems if key species vanish at any level of the food chain. One such endangered animal is the Black Rhinoceros.
The Black Rhinoceros, Diceros bicornis also colloquially Black Rhino is a mammal in the order Perissodactyla, native to the eastern and central areas of Africa including Kenya, Tanzania, Cameroon, South Africa, Namibia and Zimbabwe. Although the Rhino is referred to as a “Black” creature, it is actually more of a grey-white color in appearance. For most of the 20th century the continental black rhino was the most numerous of all rhino species. Around 1900 there were probably several hundred thousand living in Africa. During the later half of the 20th century their number severely reduced from an estimated 70,000 in the late 1960s to only 10,000 to 15,000 in 1981.
In the early 1990s the number dipped below 2500, and in 1995 it was reported that only 2,410 black rhinos remained.
According to the International Rhino Foundation, the total African population has since then slightly recovered to 3,610 by 2003. According to a July 2006 report by the World Conservation Union, a recent survey of the West African Black Rhino, which once ranged across the savannahs of western Africa but had dropped to just 10, concluded the subspecies to be extinct.
Filed under: Research | Tags: atoll, coral reefs, HellBoy, howesii, palmyra, pollution, rhodactis, shipwrecks, species, Suman Das, tourism, tribes of honolulu, unwanted
Shipwrecks on coral reefs may increase invasion of unwanted species, according to a recent U.S. Geological Survey study. These unwanted species can completely overtake the reef and eliminate all the native coral, dramatically decreasing the diversity of marine organisms on the reef.
This study documents for the first time that a rapid change in the dominant biota on a coral reef is unambiguously associated with man-made structures. The findings of the study suggest that removal of these structures sooner rather than later is key to keeping reefs healthy.
Overgrowth of coral reefs by other species, such as algae, are usually attributed to environmental degradation, but bleaching, disease, damage by typhoons, overfishing, coastal development, pollution, and tourism can cause problems as well. The study was conducted at Palmyra Atoll National Wildlife Refuge in the central Pacific, a relatively remote, comparatively pristine area where little human activity has occurred since WWII. In 1991, a 100-foot vessel shipwrecked on the a toll. Scientists first surveyed the area in 2004 and found a species called Rhodactis Howesii —an organism related to sea anemones and corals—in low abundance around the wreck.
In subsequent years, however, populations of this organism increased exponentially. Scientists documented extremely high densities of R. Howesii that progressively decreased with distance from the ship, whereas R. Howesii were rare to absent in other parts of the atoll.
They also confirmed high densities of R. Howesii around several buoys. Whether this phenomenon occurs on other coral atolls is unknown; however, in the case of Palmyra, the R. Howesii infestation is beginning to reach catastrophic proportions, according to Dr. Thierry Work, the lead author of the study and a scientist at the USGS National Wildlife Health Center, Honolulu Field Station. Within a few years, R. Howesii spread to where it now occupies nearly 1 square mile. “Why this phenomenon is occurring remains a mystery,” said Work.
One possibility, he said, is that iron leaching from the ship and mooring buoy chains, accompanied with other environmental factors particular to Palmyra atoll, are somehow promoting the growth of Rhodactis. “Given the ability of Rhodactis sp. to rapidly reproduce and completely smother reefs, managers are now facing the possibility that even with removal of the ship, sheer reproductive capacity of R. Howesii may continue to fuel its spread along the western reef shelf of Palmyra,” Work said.Understanding what constitutes a healthy underwater ecosystem, as well as what does not, is crucial to preventing further losses in species and habitat.
This research illustrates a little-known problem that, unlike global warming and pollution, could be prevented by removing man-made debris such as shipwrecks from coral reefs before organisms like Rhodactis Howesii can overtake healthy coral reefs.
