AN OVERVIEW: ECOLOGY

ECOLOGY Definition and Etymology of Ecology Ecology is the science which tries to understand how interactions between organisms and their environment happen. Ecology is the study of the relationships and interactions of living things with one another and with their external environment. Ecology comes from the Greek word oikos, which means “house” and logos which means “study.” Layers of Ecological Organization Biosphere – the part of the earth that supports life, which includes the top portion of the Earth’s crust (troposphere), all the bodies of water on the Earth’s surface (hydrosphere), and the surrounding atmosphere Ecosystem – the area in which living things interact with one another and with their environment Community – group of different species of organisms that interact with each other in a given area. A species is a group of organisms that share the same general physical characteristics and are able to interbreed and produce fertile offspring. Population – group of organisms of the same species that live in a defined area Habitat – the actual place or type of environment in which an organism or a population lives. A niche is the role of an organism has in its habitat. Components of Ecosystem Abiotic Factors – include all kinds of non-living things. Below are some abiotic factors in an ecosystem: Light Temperature Water Oxygen pH (acidity and alkalinity) Salinity (salt concentration) Biotic Factors – concern all kinds of living things, which an organism comes in contact with. Producers (Autotrophic) – mainly green plants that manufacture their own food. Certain microorganisms, such as phytoplanktons, are also producers. Photosynthesis – process of producing food using sunlight and water. Plants undergo this process. Chemosynthesis – process of producing food using chemical reactions or chemicals. Fungi and bacteria undergo this process. Consumers (Heterotrophic) – organisms that cannot make their own food and depend on producers for food and energy. They obtain their energy directly or indirectly from producers. Carnivores – animals that only eat meat Herbivores – animals that only eat plants Omnivores – animals that eat both meat and plants Scavengers – animals that feed on the bodies of dead animals Decomposers – organisms that break down dead organisms into simpler substances to enable the materials locked up in them to be returned to the physical environment and be used again by green plants. Flow of Energy in an Ecosystem Food Chain – way of describing the flow of energy in food through a community. Each stage in a food chain is known as trophic level. Producers Consumers Primary Consumer Secondary Consumer Tertiary Consumer Decomposer Food Web – network of food chains Energy Pyramid – food chain shown using a pyramid that starts with the producer at the base upward Pyramid of Numbers – it shows the number of organisms interacting in a food chain in a certain community Interrelationships in an Ecosystem Symbiosis – interaction between two organisms of different species in which at least one benefits Mutualism – symbiotic relationship in which both organisms benefit Commensalism – symbiotic relationship in which one organism benefits and the other is unaffected Commensal – organism that benefits Host – organism that is unaffected Parasitism – symbiotic relationship in which one organism benefits, while the other is harmed. Parasite – organism that benefits Endoparasite – parasite that lives inside its host’s body Ectoparasite – parasite that lives outside its host’s body Host – organism that is harmed Predation – feeding of one organism on another Predator – organism that feeds on the other organism Prey – organism eaten by a predator Competition – interaction when two species use the same limited resource Active Competition – battle occurs between two different predatory animals over a single prey Passive Competition – indirect competition between two organisms Biogeochemical Cycles Water Cycle Carbon Cycle Oxygen Cycle Nitrogen Cycle Natural and Man-made Ecosystems Natural Ecosystems Terrestrial Communities/Biomes Tropical Rain Forests Receive an incredible amount of rain Its constant moist and warm conditions make it the home of the greatest variety of plants and animals than any other land biome. Richest biome in terms of the number of species, probably containing at least half of the Earth’s species of terrestrial organisms Tropical trees stay green all year Layers of tropical rain forest: emergent layer (with the largest trees that tower above all other plants, controls how much light and water reach the lower layers); canopy layer (layer with trees that overlap into what looks like a solid green roof); understory (shady layer where plants and animals live a very difficult environment); forest floor (very dark and the air is very still and quiet). Examples: South America’s Amazon Basin, Africa’s Congo Basin, and the South Pacific’s Malay Archipelago Grasslands Areas where grass is the main type of plant Categories of grasslands: tropical grasslands (grass that grows in places where the climate is hot all year round; and temperate grasslands (grass that grows in places with hot summers and cold winters) Grasslands support the great herds of grazing animals.. Examples: Africa’s Serengati, Australian grasslands, Southeast Asia grasslands GRASSLAND LOCATION LOCAL NAME Temperate Grassland North America Shortgrass prairie Tall grass prairie South America Pampas (Argentina) Africa Veldt Asia Steppes Tropical Grassland South America Llanos Campos Africa Savannah Desert The world has twelve main desert regions Deserts are most extensive in the interiors of continents, such as in Africa, Asia, Australia, and North America. All deserts have one thing in common no matter where they are – deserts are arid. This means they are very dry. Deserts receive less than twenty-five centimeters of rain yearly. Although, most deserts have very hot climate, their evenings may be very cold. Plants and animals in a desert are adapted to the lack of rainfall. In desert regions, the vegetation is characteristically sparse. Rainfall in deserts is also unpredictable. Some deserts may not receive any rain for many years. When rain pours in the desert, some of it sinks down forming a reservoir of water. When this reaches the desert surface, an oasis forms. Animals which have adapted in desert regions are camels (Arabian deserts), ostriches (Africa), and a variety of reptiles, birds, and mammals. CONTINENT DESERT Africa Sahara Namib Kalahari Australia Australian desert Asia Arabian desert Iranian desert Thar desert (Indian and Pakistan) Gobi (China and Mongolia) Turkistan (Central Asia) South America Patagonian desert (Argentina) Atacama (Chile and Peru) North America North American Desert composed of the Great Basin Desert, Mohave Desrt, Sonoran Desert, and Chihuahuan Desert Temperate Forests Grow in milder climates The weather in a temperate climate changes with the seasons. Forest trees help keep the temperatures mild. Temperate Deciduous Forests Home to deciduous or hardwood trees that shed their leaves each winter. These trees produce flowers in spring, seeds in summer and spectacularly colored leaves in fall. Have relatively warm summers, cold winters, and sufficient precipitation It covers large areas, such as the eastern United States, southeastern Canada, and extensive areas of Europe and Asia. The hardwood trees are oaks, hickories, maples, ashes, birches, and beeches. Animals in this biome are deer, bears, raccoons, and beavers Temperate Coniferous Forests (Taiga) Trees in a coniferous forest are conifers, also called evergreen trees, which produce seeds in cones instead of flowers. Cold, wet climates promote the growth of coniferous forests. A great ring of northern forest coniferous trees, primarily spruce and fir, extends across vast areas of Eurasia and North America. This biome, one of the largest on Earth, is called by its Russian name taiga. Winters in the taiga are long and cold, and most of the precipitation falls in the summer. Many large mammals which live in the taiga include herbivores, such as elk, moose, and deer, and carnivores, such as wolves, bears, lynxes, and wolverines. Tundra Vast polar plain between the taiga and permanent ice surrounding the North Pole Covers one-fifth of the Earth’s land surface Very cold and dry Most of the water on the tundra is permanently frozen in the soil as permafrost. Foxes, lemmings, owls, and caribous are among the consumers in the tundra food chain. Algae, mosses, and lichens provide color to its plain surrounding. Aquatic Communities Marine Communities Covers about seventy percent of the earth An estimated 90 percent of all photosynthesis and release of free oxygen takes place in the oceans. The bottom can be muddy, sandy or rocky The shorelines can vary from smooth, sandy beaches to jagged, rocky cliffs, and the water can be centimeters or kilometres deep. The three major marine communities are shallow ocean waters, open sea surface, and deep seawaters. Freshwater Communities Only places where we can easily get fresh, flowing waters. Freshwater habitats – lakes, ponds, streams and rivers – are very limited in area. Lakes cover about 1.8 percent of the earth’s surface and rivers and streams cover only 0.3 percent. All freshwater habitats are strongly connected to terrestrial habitats; hence, they are easily polluted by human activities. Many organisms, such as some varieties of plants, fish, arthropods, mollusks, and other invertebrates are restricted to fresh water habitats. Ecologists divide freshwater ecosystems into bodies of running water and standing water. Freshwater communities have three zones of life, littoral, limnetic, and profundal. The littoral zone is a shallow zone near the shore where aquatic plants live among with various predatory insects, amphibians, and small fish. The limnetic zone refers to the area that is farther away from the shore but close to the surface. It is inhabited by floating algae, zooplankton, and fish. The profundal zone is a deep water zone that is below the limits of effective light penetration. Numerous bacteria and wormlike organisms that eat the debris on the lake’s bottom live in this zone. Not all freshwater ecosystems are deep enough to include a profundal zone. Open and Interdependent Ecosystems Estuaries Commonly regarded as a place where rivers meet. The estuaries’ plants and algae are stimulated to grow from the nutrients that are washed from nearby land. Estuaries are among the most productive ecosystems on Earth. Estuaries filter sediment and nutrients and purify the water that drains off the land. Porous salt-marsh soils absorb floodwaters and protect coastal communities from erosion. Many animals regard estuaries as hatching areas. Sadly, estuaries are regarded as wastelands and are currently being drained to provide land for housing and agriculture. Wetlands Basic name for a kind of ecosystem that develops where fresh or saltwater and land meet Scientists categorize wetlands as inland or coastal. Wetlands are found all over the world. They would stay wet all year or some would dry up. Examples of freshwater wetlands that are found inland are marshes, swamps, and bogs. Saltwater wetlands are found along coastlines. They include salt marshes and mangrove swamps. Amphibians, reptiles, small fishes, and water insects thrive in these places. Man-made Ecosystems Fish Pens Zoos Botanical Gardens Farms Artificial Ponds and Lakes Threats to the Ecosystem Natural Hazards Red Tide – also called as blooms, are natural phenomena caused by the explosive population of a minute, single-celled group of algae called dinoflagellates, particularly the species Karenia brevis (formerly Gymnodinium breve). El Nino – warming of an ocean that usually happens before Chirstmas occurring ever three to seven years and can affect climates around the world for more than a year La Nina – associated with colder-than-usual sea surface temperatures in the Equatorial Pacific region Man-made Hazards Bombings – the invention of weapons and bombs either protect a country from invasion or harm another. On August 6, 1945, during World War II, the first atomic bomb was dropped on Hiroshima City, Japan. The Supreme Allied Headquarters reported that 129,558 people were killed, injured or missing while 176,987 were made homeless by the bombing. The blast flattened more than 10 sq. km. (4 sq. mi.), about 60% of the city. Civilian of all ages were injured by another atomic bomb that the US dropped on Nagasaki, Japan on August 9, 1945. After the bombing, the nuclear bombs released radiation that caused serious long-term injuries to individual who survived the heat and blast of the initial explosion. Still not learning from these catastrophes brought by the Hiroshima-Nagasaki bombings, US-Terrorist wars in Afghan/Iraqi borders still continue. Nuclear Fallout – Chernobyl is a town in north-central Ukraine, located approximately 20 km. (12 mi.) from a nuclear power plant. In April 26, 1986, due to an improperly supervised experiment, one of its reactors went out of control and caused the world’s worst known reactor disaster to date. The steam explosion triggered the reactor’s protective covering to blow off, and approximately 100 million curies of radionuclides were released into the atmosphere. Some of the radiation spread across northern Europe and into Britain. 31 people died as a result of the accident, but the number of radiation-caused deaths is yet unknown although expected to be much greater. More than 100,000 people were evacuated from areas around the reactor site, and Chernobyl and some other settled regions remained unoccupied one year later. More than a decade after the Chernobyl accident, people are still restricted to inhabit or till the soil for agriculture. Areas of health concern are the increase in psychological disorders, genetic damage, and thyroid cancer in children. Deforestation – forests are being cleared by human activities to meet the demands of increasing human population. The invention of modern machineries aided the clearance of our forests much faster than they can be replaced naturally. Pollution – the process by which harmful substances are added to the environment Coral Reef Destruction Dynamite Fishing – or blast fishing, is a practice in which fishermen use explosives to kill ad harvest fish. Cyanide Fishing – this technique is used to capture fish live for aquariums, as well as for “live fish” restaurants. Divers spray cyanide solution from bottles directly onto fish resting on corals, killing the corals and shocking the fish. Human Runoff – sewage and other human waste products will eventually flow into coastal waters. Chemical fertilizers from runoff farms that flows from rivers to the sea also affects the coral reefs. Dive Tourism – divers frequently make contact with fragile corals that lead to their destruction. Muro Ami – carried out by hundreds of children swimming in a cavalry formation, smashing rocks on coral reefs, driving fish before them into their nets. Saving Our Ecosystem Convention on Biodiversity – the general objectives of this convention held in June 1992 in Rio de Janeiro are to achieve conservation of biological diversity, to make biodiversity sustainable in the long term, and to share fairly the benefits from use of genetic resources. The Montreal Protocol - In 1985, scientific evidence of the dangerous, rapid depletion of stratospheric ozone led to a United Nations convention which agreed by more than 160 countries to phase out CFCs and other ozone-destroying chemicals. The Earth Summit – the United Nations Conference on Environment and Development, held in Rio de Janeiro in 1992, delved into important issues, such as climate change, species and habitats threatened with extinction or degradation, while looking for solutions to reverse these trends. The shared goals are to manage the natural world and its resources more effectively, lessen the impacts of human activities, particularly environment pollution and waste disposal, and at the same time improve the development options for disadvantaged nations. Coral Reef Preservation – formation of the International Coral Reef Initiative (ICRI) in 1994 and the Global Coral Reef Monitoring Network (GCRMN) in 1996. The goals of the network are to provide data on the status of coral reefs of the world, and to raise awareness in all stakeholders on the status of reefs and the need for urgent action.