Endangered species, if not protected, could eventually become extinct—and extinction has a myriad of implications for our food, water, environment and even health. Ninety-nine percent of all species that have ever lived have gone extinct over the course of five mass extinctions, which, in the past, were largely a result of natural causes such as volcano eruptions and asteroid impacts.
Today, the rate of extinction is occurring 1, to 10, times faster because of human activity. The main modern causes of extinction are the loss and degradation of habitat mainly deforestation , over exploitation hunting, overfishing , invasive species, climate change, and nitrogen pollution.
There are also other threats to species such as the pervasive plastic pollution in the ocean—a recent study found that percent of sea turtles had plastic or microplastic in their systems. This loggerhead was entangled in a line dragging a plastic bucket. Photo: U.
Coast Guard, Matt Strucic. Emerging diseases affecting more and more wildlife species such as bats, frogs and salamanders are the result of an increase in travel and trade, which allows pests and pathogens to hitch rides to new locations, and warming temperatures that enable more pests to survive and spread. Wildlife trafficking also continues to be a big problem because for some species, the fewer members there are, the more valuable they become to poachers and hunters.
This includes 40 percent of amphibians, 34 percent of conifers, 33 percent of reef-building corals , 25 percent of mammals and 14 percent of birds.
In the U. While it may seem unimportant if we lose one salamander or rat species, it matters because all species are connected through their interactions in a web of life. A balanced and biodiverse ecosystem is one in which each species plays an important role and relies on the services provided by other species to survive. Healthy ecosystems are more productive and resistant to disruptions.
An often-cited example is the impact of the wolves in Yellowstone Park, which were hunted to near extinction by Without them, the elk and deer they had preyed upon thrived, and their grazing decimated streamside willows and aspens, which had provided habitat for songbirds.
This left the stream banks susceptible to erosion, and a decline in songbirds allowed mosquitoes and other insects the birds would have eaten to multiply. When the wolves were reintroduced to the park in , they once again preyed on the elk; plant life returned to the stream banks and along with it, birds, beavers, fish and other animals.
Note: David Bernhardt, acting secretary of the Department of the Interior, just announced a proposal to strip gray wolves of their endangered status in the Lower 48 states. Kelp forests are another classic example. They play an important role in coastal ecosystems because they provide habitat for other species, protect the coastline from storm surges and absorb carbon dioxide. Otter in a kelp field. Photo: Doug Knuth. Yet kelp forests are rapidly getting mowed down by exploding numbers of purple sea urchin.
California sea otters eat the purple sea urchins that feed on giant kelp. These otters used to number in the hundreds of thousands to millions, but their population has been reduced to about 3, as a result of unchecked hunting in the 19th century and pollution. Moreover, in the sunflower starfish, which also eats purple sea urchins, began dying because of a virus that was likely exacerbated by warmer waters.
Without the sea otter and the sunflower starfish predators, the purple sea urchin began feasting on the kelp forests, which declined 93 percent between and A new study found that kelp forests are now also threatened by ocean heat waves.
Fish that need the kelp forests for spawning, such as sculpin, rock cod and red snapper may become vulnerable in the future as well. And Guam is covered in spiders because the birds are not there to eat them. These large species are more vulnerable because they live longer, reproduce more slowly, have small populations, and need more food and a greater habitat area.
Scientists say their loss has played a role in pandemics, fires, the decline of valued species and the rise of invasive ones, the reduction of ecosystem services, and decreased carbon sequestration. Elephants are an apex species that may go extinct in our lifetime, as a result of tourism, habitat loss and poaching for ivory. This could dramatically change ecosystems in Africa and Asia. Through consumption and digestion, elephants disperse more seeds farther than any other animals; this fosters the growth of plants and trees that birds, bats and other animals depend upon for food and shelter.
Photo: Johnny and Rebecca. Elephants also dig water holes that all animals share, and they fertilize the soil with their rich dung, which provides food for other animals. Findings revealed that almost half of the islands suffered losses of fruit-eating species and, on average, around one-third of the original communities on these islands also disappeared.
Animals are not the only living beings influenced by extinctions. Plants are also greatly affected when one or more species of fruit-eating island animals goes extinct.
When fruit-eating animals disappear, trees, in particular, are deprived of an essential mechanism for relocating their seeds to new areas, so they too, face extinction. As the saying goes, pulling on a loose thread of yarn can unravel an entire sweater. The same concept applies to how plants and animals depend on each other and how microorganisms, land, water, and climate together keep our entire system healthy.
Our current biodiversity crisis — dubbed by some experts as the Sixth Extinction — is becoming more pressing than ever, as the pace of anthropogenic change encroaches on nature. Current extinction rates are a thousand times higher than natural background rates, according to a study in Conservation Biology. After a while, these seeds will come out again and land somewhere else. This is how many plants move between different areas and make sure their little seeds can grow up in a good spot.
If there are no animals left to spread seeds, the plants are at risk of becoming extinct themselves. An island without animals and plants would be a lot less exciting than what the early explorers encountered.
Read More: Mass extinction 66 million years ago paved the way for modern shark communities. In our research, we wanted to know just how bad the situation was for fruit-eating animals on islands across the world.
Were some animals more likely to go extinct then others? Have there been more extinctions on certain types of islands? Together with my colleagues Daniel Kissling and Emiel van Loon from the University of Amsterdam, and Dennis Hansen from the Zoological Museum of Zurich, we investigated data from 74 islands across the world. We wanted to get the full picture, so we looked at all of the birds, mammals, and reptiles that eat fruit.
We also included animals that have recently become extinct. We checked to see whether the island size and remoteness could explain differences between the numbers of extinctions that we found.
Then, we compared characteristics between the animals that had gone extinct with those that survived, such as differences in their weight and whether or not they can fly. Many large animals that eat fruit birds, tortoises, lizards, bats have gone extinct on islands. The remaining small animals cannot swallow and disperse the largest fruits and those plants are now at risk of extinction too. We saw that large animals that cannot fly go extinct more often than any other.
The Dodo bird on Mauritius is a famous example. But interestingly, we saw a knock-on effect of such extinctions. In fact, the mean weight of all fruit-eating animals on islands has reduced by 37 per cent due to the loss of large animals, such as a giant bird on New Caledonia, several large flying foxes and some of the Galapagos giant tortoises.
Many of the islands in our study have lost their biggest fruit-eating animal and sometimes also the second biggest. Today, only the smallest animals remain. Our data show that the largest animals that can be found on islands today are 51 per cent smaller than the largest animals that used to live there.
The loss of so many large fruit-eaters is extra challenging for the plants. This is because large fruit-eaters have larger beaks and mouths and can swallow the largest fruits. The smaller animals that remain on the islands today are simply not capable of swallowing and dispersing large fruits.
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