Sustaining Biodiversity The Species Approach Chapter 8 Section

Sustaining Biodiversity: The Species Approach Chapter 8

Section 8 -1 WHAT ROLE DO HUMANS PLAY IN THE EXTINCTION OF SPECIES?

Extinctions are natural but sometimes they increase sharply • Biological extinction occurs when a species can no longer be found anywhere on the earth. • The disappearance of species can weaken or break some of the connections in the ecosystem. • The extinction of many species in a relatively short period of geologic time is called a mass extinction.

Some human activities are causing extinction rates to rise • Extinction is a natural process but evidence indicates that extinction has accelerated as the human population has increased, consuming huge quantities of resources and creating large and growing ecological footprints. • Scientists from around the world have estimated that the current annual rate of species extinction is at least 100 to 1, 000 times the background rate. • The annual extinction rate is projected to rise to about 1% per year, mostly because of habitat loss and degradation, climate change, and other environmentally harmful effects of human activities. • At a 1% extinction rate, 25% - 50% of the world’s current species could vanish by the end of this century.

Some human activities are causing extinction rates to rise • A projected extinction rate of 1% a year may be on the low side, for several reasons. – The rate of species loss and the extent of biodiversity losses are likely to increase sharply during the next 50– 100 years due to projected growth of the human population. – Current and projected extinction rates are much higher than the global average in parts of the world that are already highly endangered centers of biodiversity. – Humans are creating a speciation crisis by eliminating or degrading many biologically diverse environments that are potential sites for the emergence of new species.

Some human activities are causing extinction rates to rise • Human activities might help to increase the speciation rates for other rapidly reproducing opportunist species such as weeds, rodents, insects, which could further accelerate the extinction of other species.

Endangered and threatened species are ecological smoke alarms • An endangered species has so few individual survivors that the species could soon become extinct over all or most of its natural range. • A threatened species (vulnerable species) still has enough remaining individuals to survive in the short term, but because of declining numbers, it is likely to become endangered in the near future. • Some species have characteristics that make them especially vulnerable to ecological and biological extinction.

Characteristics that can put certain species in greater danger of extinction

Characteristic Low reproductive rate Examples Blue whale, giant panda, rhinoceros Specialized niche Blue whale, giant panda, Everglades kite Narrow distribution Elephant seal, desert pupfish Feeds at high trophic level Bengal tiger, bald eagle, grizzly bear Fixed migratory patterns Blue whale, whooping crane, sea turtle Rare African violet, some orchids Commercially valuable Snow leopard, tiger, elephant, rhinoceros, rare plants and birds Large territories California condor, grizzly bear, Florida panther Fig. 8 -3, p. 154

Percentages of various species threatened with extinction due to human activities

Plants 70% 34% (37% of freshwater species) Fishes Amphibians 30% Reptiles 28% Mammals Birds 21% 12% Fig. 8 -4, p. 155

Section 8 -2 WHY SHOULD WE CARE ABOUT THE RISING RATE OF SPECIES EXTINCTION?

Species are a vital part of the earth’s natural capital • Three major reasons why we should work to prevent our activities from causing the extinction of other species: – The world’s species provide natural resources and natural services that help to keep us alive and support human economies. – Various plant species provide food crops, fuelwood and lumber, paper, and medicine. • Preserving species also provides economic benefits through wildlife/eco tourism.

Species are a vital part of the earth’s natural capital • Analysis of past mass extinctions indicates that it will take 5– 10 million years for natural speciation to rebuild the biodiversity that we are likely to destroy during your lifetime. • Many people believe that each wild species has a right to exist, regardless its usefulness to us.

Section 8 -3 HOW DO HUMANS ACCELERATE SPECIES EXTINCTION?

Loss of habitat is the single greatest threat to species: Remember HIPPCO • HIPPCO summarizes the most important causes of extinction from human activities: – Habitat destruction/degradation/fragmentation. – Invasive (nonnative) species. – Population growth/increasing use of resources. – Pollution. – Climate change. – Overexploitation.

Loss of habitat is the single greatest threat to species: Remember HIPPCO • Scientists say that the greatest threat to wild species is habitat loss, degradation, and fragmentation. The greatest eliminators of species are, in order: – Deforestation in tropical areas. – Destruction and degradation of coral reefs and wetlands. – Replacement of biologically diverse grasslands with monoculture crops. – Pollution of streams, lakes, and oceans.

Reductions in the ranges of four species

Indian Tiger Range 100 years ago Range today African Elephant Probable range 1600 Range today Black Rhino Range in 1700 Range today Asian or Indian Elephant Former range Range today Stepped Art Fig. 8 -6, p. 157

Loss of habitat is the single greatest threat to species: Remember HIPPCO • Island species, often endemic species found nowhere else on earth, are especially vulnerable to extinction. • Habitat fragmentation—by roads, logging, agriculture, and urban development—occurs when a large, intact area of habitat is reduced in area and divided into smaller, more scattered and isolated patches, or “habitat islands. ” • Most national parks and other nature preserves are habitat islands.

We have introduced species that can disrupt ecosystems • After habitat loss and degradation, the biggest cause of animal and plant extinctions is the deliberate or accidental introduction of harmful invasive species into ecosystems. • Most species introductions are beneficial to us, such as food crops, livestock and harvestable trees. • Problems arise when introduced species have no natural predators, competitors, parasites, or pathogens to help control their numbers in their new habitat.

Harmful invasive species

Deliberately Introduced Species Purple loosestrife European starling African honeybee Nutria (“Killer bee”) Salt cedar (Tamarisk) Purple loosestrife African honeybee. Water hyacinth Japanese beetle European wild (“Killer Bee”) boar (Feral pig) Fig. 8 -7 a, p. 159

Accidentally Introduced Species Sea lamprey (attached to lake trout) Argentina fire ant Brown tree snake Formosan termite Zebra mussel Fig. 8 -7 b, p. 159

We have introduced species that can disrupt ecosystems • An estimated 7, 100 species introduced into the US have caused ecological and economic harm. • CASE STUDY: The Kudzu Vine. – A deliberately introduced plant species; grows rampant in the southeastern US and is known as ‘the vine that ate the South’. – In the 1930 s, this vine was imported from Japan and planted in the southeastern US in an attempt to control soil erosion.

House overtaken by kudzu

Some accidentally introduced species can disrupt ecosystems • Many unwanted nonnative invaders arrive from other continents as stowaways on aircrafts, ships, wooden packing crates, on cars, or with tourists. • Terrestrial examples include: – The aggressive Argentina fire ant which has spread over much of the southern US. Fire ants can wipe out native ant populations. Fire ant mounds can cover fields and yards. When disturbed, up to 100, 000 ants may attack with painful, burning stings. They have killed deer fawns, birds, livestock, pets, and at least 80 people who were allergic to their venom.

Some accidentally introduced species can disrupt ecosystems – Pythons and boa constrictors have ended up in the Everglades in Florida after being dumped by their owners. Some reach 20 feet long and 200 pounds. They are hard to find and kill, and they reproduce rapidly. They devour birds, raccoons, pet cats and dogs, full-grown deer and alligators. Tens of thousands of these snakes now live in the Everglades and they may spread to other swampy wetlands in the southern half of the US.

Some accidentally introduced species can disrupt ecosystems • Bioinvaders also affect aquatic systems and are blamed for about two-thirds of fish extinctions in the US between 1900 and 2009 – The Great Lakes of North America have been invaded by more than 185 alien species. At least 13 of the recent invading species threaten some native species and cause billions of dollars in damages. – Fish-killing sea lamprey. – Zebra mussel - displaced some species, depleted the food supply for others and clogged pipes, shutting down water intake pipes for power plants and city water supplies, jammed ship rudders, and grown in huge masses on boat hulls, piers and other solid surfaces.

Zebra mussels attached to a water current meter in Lake Michigan

Prevention is the best way to reduce threats from invasive species • Scientists suggest several ways to do this: – Fund a massive research program to identify the major characteristics that allow species to become successful invaders and the types of ecosystems that are vulnerable to invaders. – Greatly increase ground surveys and satellite observations to detect and monitor species invasions and to develop better models for predicting how they will spread and what harmful effects they might have.

Prevention is the best way to reduce threats from invasive species – Identify major harmful invader species and establish international treaties banning their transfer from one country to another, as is now done for endangered species, while stepping up inspection of imported goods to enforce such bans. – Require cargo ships to discharge their ballast water and replace it with saltwater at sea before entering ports, or require them to sterilize such water or to pump nitrogen into the water to displace dissolved oxygen and kill most invader organisms. – Educate the public about the environmentally harmful effects of releasing exotic plants and pets into the environment near where they live.

Ways we can slow or prevent the spread of invasive species

Population growth, overconsumption, pollution, and climate change can cause species extinctions • Past and projected human population growth and excessive and wasteful consumption of resources have greatly expanded the human ecological footprint, impacting other species. • Pollution also threatens some species with extinction, as has been shown by the unintended effects of certain pesticides. – Each year pesticides kill about 20% of the honeybee colonies that pollinate almost 33% of U. S. food crops, kill more than 67 million birds and 6– 14 million fish each year, and threaten about 20% of the country’s endangered and threatened species.

Population growth, overconsumption, pollution, and climate change can cause species extinctions – The pesticide DDT can be biomagnified about 10 million times in an estuary food chain, causing animals such as the osprey, brown pelican and bald eagles to die. • Projected climate change could help drive a quarter to half of all land animals and plants to extinction by the end of this century.

Bioaccumulation and biomagnification

DDT in fish-eating birds (ospreys) 25 ppm DDT in large fish (needlefish) 2 ppm DDT in small fish (minnows) 0. 5 ppm DDT in zooplankton 0. 04 ppm DDT in water 0. 000003 ppm, or 3 ppt Fig. 8 -11, p. 162

CASE STUDY: Where Have All The Honeybees Gone? • About one-third of the U. S. food supply comes from insect-pollinated plants, and honeybees are responsible for 80% of that pollination. • A 30% - 40% drop in U. S. honeybee populations has been reported since the 1980 s, due to: – – – Pesticide exposure. Parasitic mites - can wipe out a colony in hours. Invasion by Africanized honeybees. A virus traced to Israel, and a certain fungus. Poor nutrition because of a decrease in the natural diversity of flowers and other plants on which bees feed.

CASE STUDY: Where Have All The Honeybees Gone? • In 2010, about 34% of commercial honeybee colonies in the U. S. were lost in part to colony collapse disorder (CCD), causing adult bees to mysteriously disappear. • Strategies to help honeybee populations: – Beekeepers are reducing CCD by practicing stringent hygiene, improving the diets of the bees, and trying to reduce viral infections. – Cut back on use of pesticides, especially at midday when honeybees are most likely to be searching for nectar. – Make our yards and gardens into buffets for honey bees by planting native plants that they like. – Bees need places to live, so some homeowners are purchasing bee houses from their local garden centers.

Illegally killing, capturing, and selling wild species threatens biodiversity • Some protected species are poached for their valuable parts or are sold live to collectors. • The global illegal trade in wildlife brings in an average of at least $600, 000 an hour and at least 66% of all live animals smuggled around the world die in transit. Organized crime has moved into illegal wildlife smuggling because of the huge profits involved. • Examples include: – A highly endangered, live mountain gorilla is worth $150, 000.

Male mountain gorilla

Illegally killing, capturing, and selling wild species threatens biodiversity – The pelt of a critically endangered giant panda can bring $100, 000. – A poached rhinoceros horn can be worth $25, 000 per pound. Rhinoceros are killed only for their horns. – About 25, 000 African elephants are killed illegally each year for their ivory tusks despite an international ban on the sale of poached ivory since 1989. – A coat made from the fur of the Indian or Bengal tiger can sell for as much as $100, 000 in Tokyo, and the body parts of a single tiger are worth as much as $70, 000. Without emergency action to curtail poaching and preserve their habitat, few if any tigers may be left in the wild within 20 years.

Poached white rhinoceros

Illegally killing, capturing, and selling wild species threatens biodiversity – More than 60 bird species, mostly parrots, are endangered or threatened because of the wild-bird trade. – The pet trade is depleting populations of many amphibians, various reptiles, some mammals, and many tropical fishes. For each fish caught alive, many more die, and the cyanide used to stun tropical fish also kills the coral polyps that build reefs. – Some exotic plants are endangered when they are gathered to for houseplants and landscapes. Collectors may pay $5, 000 for a rare orchid or $15, 000 for a saguaro cactus.

Rising demand for bush meat threatens some African species • Indigenous people in much of West and Central Africa have sustainably hunted wildlife for bush meat, a source of food, for centuries. • In the last two decades, bush meat hunting in some areas has skyrocketed as hunters try to provide food for rapidly growing populations or to make a living by supplying restaurants with exotic meats. • Bush meat hunting has led to the local extinction of many wild animals, driven one species of colobus monkey to complete extinction, and been a factor in reducing some populations of orangutans, chimpanzees, elephants, and hippopotamuses.

CASE STUDY: A Disturbing Message from the Birds • Approximately 70% of the world’s known bird species are declining in number. • The primary culprits appear to be habitat loss and fragmentation.

Section 8 -4 HOW CAN WE PROTECT WILD SPECIES FROM EXTINCTION?

International treaties and national laws can help to protect species • The 1975 Convention on International Trade in Endangered Species (CITES) is a far-reaching treaty signed by 174 countries that bans the hunting, capturing, and selling of threatened or endangered species. • The Convention on Biological Diversity (CBD), ratified by 190 countries (but as of 2011, not by the United States), legally commits participating governments to reversing the global decline of biodiversity and to equitably sharing the benefits from use of the world’s genetic resources.

The U. S. Endangered Species Act • The Endangered Species Act of 1973 (ESA; amended in 1982, 1985, and 1988) was designed to identify and protect endangered species in the United States and abroad. • Under the ESA, the National Marine Fisheries Service (NMFS) is responsible for identifying and listing endangered and threatened ocean species, while the U. S. Fish and Wildlife Service (USFWS) is to identify and list all other endangered and threatened species. • Any decision to add or remove a species on the list must be based on biological factors alone without consideration of economic or political factors.

The U. S. Endangered Species Act • The ESA forbids federal agencies (except the Defense Department) to carry out, fund, or authorize projects that would jeopardize an endangered or threatened species, or destroy or modify its critical habitat. • For offenses committed on private lands, fines as high as $100, 000 and 1 year in prison. • Between 1973 and 2011, the number of U. S. species on the official endangered and threatened species lists increased from 92 to more than 1, 320.

The U. S. Endangered Species Act • Since 1982, the ESA has been amended to give private landowners economic incentives to help save endangered species living on their lands. • Some believe that the ESA should be weakened or repealed, and others believe it should be strengthened and modified to focus on protecting ecosystems. • The ESA and international agreements have been used to identify and protect endangered and threatened marine species such as seals, sea lions, sea turtles, and whales.

CASE STUDY: Protecting Endangered Sea Turtles • Six of the world’s seven sea turtle species are critically endangered or endangered. • Two major threats to sea turtles are loss or degradation of beach habitat (where they come ashore to lay their eggs and the young hatch), and the legal and illegal taking of their eggs.

Endangered leatherback sea turtle tangled in a fishing net

CASE STUDY: Protecting Whales: A Success Story. . . So Far • Easier to kill due to their large size and their need to come to the surface to breathe. – Whalers killed an estimated 1. 5 million whales between 1925 and 1975, driving 8 of the 11 major species to commercial extinction and driving the blue whale, the world’s largest animal, to the brink of biological extinction. – The International Whaling Commission estimates some whale species are recovering, but many conservationists fear that opening the door to any commercial whaling may weaken international disapproval and legal sanctions. – Despite the ban on whaling, more than 28, 000 whales were hunted and killed between 1986 and 2010, mostly by the nations of Japan, Norway, and Iceland, which have openly defied the ban.

We can establish wildlife refuges and other protected areas • In 1903, President Theodore Roosevelt established the first U. S. federal wildlife refuge at Pelican Island, Florida, to help protect birds such as the brown pelican from extinction. • The National Wildlife Refuge System grew to 553 refuges by 2011. • More than three-fourths of the refuges serve as wetland sanctuaries that are vital for protecting migratory waterfowl.

We can establish wildlife refuges and other protected areas • One-fifth of U. S. endangered and threatened species have habitats in the refuge system, and some refuges have been set aside for specific endangered species, such as Florida’s Key deer, the brown pelican, and the trumpeter swan. • Harmful activities to wildlife such as mining, oil drilling, and use of off-road vehicles occur in nearly 60% of the nation’s wildlife refuges. • Wildlife refuges receive little funding; a third of them have no staff, and structures in some refuges are in disrepair.

Gene banks, botanical gardens, and wildlife farms can help to protect species • Gene or seed banks preserve genetic information and endangered plant species by storing their seeds in refrigerated, low-humidity environments. • More than 100 seed banks worldwide collectively hold about 3 million samples, however: – Some species cannot be preserved in gene banks. – The banks are expensive to operate and can be destroyed by fires and other mishaps. – A new underground vault on a remote island in the Arctic will eventually contain 100 million of the world’s seeds and will not be vulnerable to power losses, fires, storms, or war.

Gene banks, botanical gardens, and wildlife farms can help to protect species • The world’s 1, 600 botanical gardens and arboreta contain living plants, representing almost one-third of the world’s known plant species but only about 3% of the world’s rare and threatened plant species. • Some endangered or threatened species are raised on farms for commercial sale, such as alligator farms in Florida and butterfly Papua New Guinea.

Zoos and aquariums can protect some species • Zoos, aquariums, game parks, and animal research centers are being used to preserve some individuals of critically endangered animal species, with the longterm goal of reintroducing the species into protected wild habitats. • Two preserving techniques are: 1. Egg pulling, where wild eggs laid by critically endangered bird species are collected and then hatched in zoos or research centers.

Zoos and aquariums can protect some species 2. Captive breeding, where some or all of the wild individuals of a critically endangered species are captured for breeding in captivity, with the aim of reintroducing the offspring into the wild. • Limited space and budgets restrict efforts to maintain breeding populations of endangered animal species that are large enough to avoid extinction through accident, disease, or loss of genetic diversity due to inbreeding.

The precautionary principle • Biodiversity scientists call for us to take precautionary action to help prevent premature extinctions and loss of biodiversity. – The principle advocates that when substantial preliminary evidence indicates that an activity can harm human health or the environment, we should take precautionary measures to prevent or reduce such harm even if some of the cause -and-effect relationships have not been established scientifically.

The precautionary principle • Using limited financial and human resources to protect biodiversity based on the precautionary principle involves dealing with three important questions: – How do we allocate limited resources between protecting species and protecting their habitats? – How do we decide which species should get the most attention in our efforts to protect species? – How do we determine which areas of land water are the most critical to protect?

Three big ideas • We are greatly increasing the extinction of wild species by destroying and degrading their habitats, introducing harmful invasive species, and increasing human population growth, pollution, climate change, and overexploitation. • We should avoid causing the extinction of wild species because of the economic and ecological services they provide, and because their existence should not depend primarily on their usefulness to us. • We can work to prevent the extinction of species and to protect overall biodiversity by using laws and treaties, protecting wildlife sanctuaries, and making greater use of the precautionary principle.