Biodiversity refers to the variability of life. This includes diversity in the number of species, genetic diversity found within species and the diversity ecosystems. The number of species present is the easiest form of biodiversity to grasp, but even this is extremely difficult to pin down in practice. Recent estimates of the number of species on Earth range from 5 million to 100 million. The number so far identified and named is about 1.9 million—somewhere between 2% and 40% of those that may exist.
Collectively, all human beings are playing a crucial role in the sixth major extinction event to occur in the course of more than three billion years of life on Earth, and the first in the past 65 million years. Species are being driven to extinction thousands of times faster than new ones can evolve. One-third of U.S. native terrestrial and freshwater aquatic species are at risk of extinction.
Approximately 20% of the world’s coral reefs were lost and an additional 20% degraded in the last several decades of the twentieth century. The oceans, which support the greatest abundance of life on earth and provide us with protein that is estimated at $31 trillion a year, are now in trouble. Ninety percent of the big fish species are gone, including tuna, swordfish and sharks. It is estimated that seafood populations could be decimated in 40 years. For a quick overview on ocean issues, watch: http://www.oneworldoneocean.org/video/entry/why-the-ocean
For a video on shark conservation issues, produced by fourth graders in Missouri, go to: rbskids.net and click on the miniature screen in the center of the page.
Oceans face plastic pollution, 80 percent of which comes from activities on land. This mockumentary sums up the impact each plastic bag makes on ocean pollution: http://www.youtube.com/watch?v=GLgh9h2ePYw
— Anukriti Sud Hittle