Changes in Biodiversity

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1 Think of the ocean, and you may imagine the fascinating creatures that live in its depths. The world s largest animal, the blue whale, and perhaps its fiercest predator, the great white shark, share the ocean with tiny photosynthetic algae. These algae, called phytoplankton, produce up to 90% of the world s oxygen. About one million ocean species are currently known. However, some scientists estimate the true number to be nearly ten times greater. photosynthetic: describes organisms that can use carbon dioxide and energy from sunlight to produce oxygen The biodiversity of ocean life is also important for humans. The 2008 Nobel Prize for chemistry was awarded to three scientists who investigated a chemical isolated from the jellyfish Aequorea victoria. This chemical, named green fluorescent protein (GFP), emits a fluorescent green color. Scientists attached GFP to other molecules within living cells and tissues, and for the first time, they could see the inner workings of living cells under a microscope. GFP has revolutionized molecular and medical science. This model illustrates the structure of green fluorescent protein. GFP has dramatically advanced our understanding of cell structure and cell processes. Scientists can now visualize what makes some of those processes go wrong in diseases. Other uses for GFP exist in stem cell medicine and gene therapy. It is impossible to project how many lives will be helped as a result of this jellyfish chemical. But, what if the Aequorea victoria had become extinct before the discovery of GFP? Throughout history, human activities such as hunting, fishing, and deforestation have caused the extinction of many species, including the dodo, silver trout, and Bali tiger. How else might human activities harm the ocean and other ecosystems? Why is it critical that we conserve the health of our ecosystems? People rely on ecosystems. Oceans or marine ecosystems are indispensible resources for life on Earth. Oceans cover more than 70% of the planet s surface. Algae in the oceans consume carbon dioxide and produce oxygen. Oceans also play critical roles in regulating Earth s climates and weather. They do this by absorbing and releasing heat energy. Weather patterns around the world are also a result of ocean temperatures and currents. For example, regions along a coastline typically have more moderate climates than regions further inland. It is these properties of oceans that help make Earth s climate suitable for life. extinct: describes a species that has completely died out The Atlantic Gulf Stream transfers heat up the eastern coast of the United States and down the western coast of Europe. Because of this current, climates in these regions are more moderate year-round. 1

2 You may think that humans need freshwater much more than we need saltwater. Yet people rely on Earth s oceans for a wide variety of purposes. Most goods and products are transported between countries via shipping routes throughout the ocean. Useful minerals and resources such as gold, silver, metal ores, and oil are retrieved through mining the ocean floor. Humans also enjoy recreational activities in the ocean, such as swimming, diving, sailing, and snorkeling among coral reefs. Most cultures of the world consume a great deal of ocean life as food. Many of these food sources are harvested from ocean systems such as estuaries and kelp forests. Estuaries are coastal water bodies that receive river flow and open into the ocean. Kelp forests are open ocean ecosystems based around marine algae populations. Kelp forests contain a large diversity of ocean life, such as fish, shellfish, and crustaceans. Human activities have modified Earth s ocean systems in many ways and with various consequences. In addition to relying heavily on Earth s oceans, humans also perform numerous activities that impact ocean systems. One of the most concerning impacts of human activity is water pollution. Water pollution is the addition of harmful substances and chemicals to natural water. Water pollution occurs in many different ways. Although illegal in many places, one source of water pollution is dumping wastes into sewers or rivers that empty into the ocean. Pollutants are sometimes dumped directly into the ocean. Contaminants in the land also cause water pollution. For instance, fertilizers and pesticides from farms accumulate in the soil. When rain and other water moves through the soil, the water dissolves and moves the pollutants. The runoff that results can eventually empty into oceans. 2

3 Pesticide runoff can poison marine organisms, whereas fertilizer runoff can cause populations of bacterial and algal populations to explode, crowding out other organisms and reducing biodiversity. Spills from ships such as oil tankers also pollute the oceans. Humans impact the oceans through overharvesting. This involves harvesting a resource at an unsustainable level. Marine life is sometimes fished until populations are nearly or completely wiped out. Changing the population sizes of different species also disturbs the balance of marine food webs. If prey animals die off, the predators that depend on them also die. On the other hand, if predators die off, prey animal populations may grow out of control. One way that humans attempt to compensate for overharvesting is to use artificial reefs. Artificial reefs are human-made underwater structures that promote marine life by providing surfaces for marine plants and animals to attach to on the ocean floor. These human-made ecosystems can support complex food webs. However, there are concerns with artificial reefs. Often they are made out of old objects such as oil rigs, train cars, and boats. Such materials may release toxic chemicals into the ocean. Humans also modify ocean systems by introducing new species into non-native ecosystems. Such invasive species disrupt the biodiversity and food webs by This ship was intentionally sunk in Australian waters to form an artificial reef. competing with or harming species native to that ecosystem. Invasive species can also promote the spread of disease, because they may carry germs to which native species have never been exposed. Invasive species can be introduced in a number of ways. Ships unintentionally pick up various marine plants, animals, bacteria, and viruses and transport them to other locations. Humans also dump exotic aquarium species into waterways that lead to the ocean. What do you think are some of the consequences of polluting ocean waters? If marine life is poisoned and killed as a result of pollution, what are some further consequences of this poisoning? How are other species and food webs affected? 3

4 In order to reduce the effects of overharvesting, many commercially sold fish are raised in compact fish farms. But there is controversy about the benefits and drawbacks of fish farming particularly when it happens in waters that flow into oceans or lakes. One problem is that fish farms lead to the accumulation of high concentrations of waste chemicals and other forms of pollution. The polluted waters can seep into natural ecosystems and harm wild fish. The pollution also supports bacterial growth. Excessive bacteria can remove oxygen from surrounding waters. In some cases, the need for wild fish to feed certain species of farmed fish can actually worsen overharvesting. Farming conditions also cause the spread of parasites and diseases through wild marine life. To combat this problem, farmed fish are often given antibiotics and other drugs. This open-sea fish farm may pose contamination problems to the surrounding waters and health hazards to those who eat the fish. There are a number of health concerns with eating many species of farmed fish. Farmed fish often contain elevated levels of various toxins. One reason is that fish farms located close to the shore are directly exposed to land runoff. Those who eat fish also consume the hormones and antibiotics fed to the fish. Furthermore, farmed fish are sometimes fed grain diets from land farms that use pesticides and other chemicals. Humans who eat these fish are then exposed to the same chemicals. Fish farming practices can be improved by addressing some of these problems individually. One potential improvement is a method of fish farming that takes place indoors. These farms do not threaten wild habitats and marine species. Career Corner: Conservation Biologist Conservation biology is an increasingly important field of study as human impact on the environment intensifies.these scientists research living species and their environments.they learn how human activities alter those environments. Conservation biologists dedicate their careers to preserving Earth s living and non-living resources. They typically earn a college degree that focuses on biology. You can practice being a conservation biologist by developing possible solutions to protecting the oceans. Remember sometimes parts of different solutions can be combined to create a solution that is better than any of its predecessors. 4

5 What specifically do these scientists do? A conservation biologist may measure the change in water quality in a particular ocean ecosystem. He or she can determine how quickly the ecosystem is becoming polluted and why. Another project for a conservation biologist may involve measuring the amount of mercury accumulation in a certain fish population. Information like this is critical for determining health concerns for species that eat those fish, including humans. Conservation biologists work in many sectors, including the government, non- profit organizations, and private companies. They play an invaluable role in promoting the health of our planet. Human activities that pollute Earth s atmosphere can also affect Earth s oceans. Many members of the world s scientific community believe that human activities contribute to global warming. Burning fossil fuels like gasoline and coal releases greenhouse gases, such as carbon dioxide and nitrous oxides, into the atmosphere. These gases trap heat on Earth s surface. But, how might global warming affect Earth s oceans? This biologist, working for the U.S. Fish and Wildlife Service, is studying endangered loggerhead turtles on a beach in Florida. global warming: a trend of climate change observed by scientists that shows average temperatures on Earth to be gradually increasing Warm air warms water at Earth s surface. Therefore, as air temperature increases, the temperature of Earth s oceans also increases. As water warms, it expands. Warmer air also melts ice at Earth s surface, and the melted ice flows into the oceans. As a result, many scientists predict that sea levels will rise in the future. One major consequence of rising sea levels is the destruction of coastal habitats. It is important to remember that coastal habitats are home to many of the world s most populous cities and communities. In addition to rising sea levels, greenhouse gases also impact the weather. Polluted water that falls from the sky, such as rain or snow, is called acid precipitation, which can contaminate both land and water ecosystems. 5

6 What Do You Know? Humans rely on the ocean for a wide variety of resources. However, many human activities impact ocean ecosystems. While some of these impacts have positive consequences, many lead to negative consequences. Below are a list of human activities and a list of some consequences of those activities. Match each activity with the consequences it can cause. Keep in mind that human activities may have several consequences. Human Activities 1. Overusing fertilizers and pesticides for agriculture 2. Dumping trash into the ocean 3. Farming fish for commercial sales 4. Emitting gases that contribute to global warming into the atmosphere 5. Constructing artificial reefs Consequences A. Bacterial or algal overgrowth B. Removal of oxygen from marine waters C. Death of fish or other marine life D. Accumulation and spread of toxic chemicals in ocean habitats E. Destruction of coastal land habitats F. Disruption of marine food webs G. Endangerment or extinction of entire marine populations or species H. Reduce the impact of overharvesting I. Spread of disease J. Rising sea levels K. Toxic chemical consumption by humans L. Acid precipitation over oceans 6. Overharvesting marine species 7. Introducing exotic marine species into new ecosystems 6

7 Observing Our Impact on Ocean Resources To help your child learn more about the impact of human activities on ocean resources, visit a local beach or possibly a river that runs to an ocean. Look for any signs of littering or pollution. Your child may also use Internet resources to investigate the water quality of that particular beach or river location. You might encourage your child to organize a beach clean-up day with other classmates if there is a local beach facing significant pollution. If this type of ecosystem is difficult to access, you may also take your child to a local fish market or the seafood section of a grocery store. You may want to visit a local fish farm if one is available. Have your child observe which species of fish and other seafood at the market are caught wild. Which species are sold farm-raised? Here are some questions to discuss with your child: How can individuals and local and national governments reduce the pollution of marine ecosystems? What are some of the specific dangers to marine life and marine habitats posed by various forms of pollution? For example, what might be the impact of plastic six-pack soda can rings, non-biodegradable materials, fertilizers from nearby farms, household cleaning agents, and oil spills? What health concerns are posed by various farm-raised fish, such as salmon, tilapia, or sea bass? 7