Lecture 2: Principles of Ecology: Matter, Energy, and Life

Principles of Ecology: Matter, Energy, and Life LECTURE 2 Learning Objectives Define/describe matter and energy Understand the principles of conservation of matter and energy, and appreciate how the laws of thermodynamics affect living systems Explain how photosynthesis captures energy for...

Principles of Ecology: Matter, Energy, and Life LECTURE 2 Learning Objectives Define/describe matter and energy Understand the principles of conservation of matter and energy, and appreciate how the laws of thermodynamics affect living systems Explain how photosynthesis captures energy for life and how cellular respiration releases that energy to do useful work Discuss food chain, food web, and trophic levels in biological communities Principles of matter and energy How and why materials are cycles between the living and non-living parts of our environment are the domain of ecology Ecology - the scientific study of relationships between organisms and their environment.  Every organism uses matter and energy from its environment and transforms them into structures and processes that make life possible. Organisms are made of inorganic compounds and organic compounds to understand how ecosystem function, it is important first to know something of how energy and matter behave – both in the universe and in the living things. What is matter? Matter – everything that takes up space and has mass Has three interchangeable physical forms, or phases: gas, liquid, and solids Example: water Under ordinary circumstances, matter is neither created nor destroyed but is recycled over and over again Conservation of matter: implies that, as we use more resources to produce more “disposable” goods, we should pay attention to where our waste products go. What is energy? energy is the capacity to do work, such as moving matter over a distance. Kinetic energy is energy contained in moving objects Potential energy is stored energy that is latent but available for use. Chemical energy, stored in the food you eat and the gasoline you put in the car, is also a potential energy that can be released to do useful work. measured in units of heat (calories) or work (joules) 1 J = 1 kg m2/s2 calorie can also be measured as 4.184 J.  Heat describes the energy that can be transferred between objects of different temperature. A substance can have low temperature but a high heat content, as in the case of a lake that freezes slowly in the fall. Other objects, such as a burning match, have a high temperature but little heat content. Low-quality energy is diffused, dispersed, or low in temperature, so it is difficult to gather and use for productive purposes. This distinction is important because many of our most common energy sources are low-quality and must be concentrated or transformed into high-quality before they are useful to us. Why is understanding heat and energy important to understanding environmental science? the concepts that energy can be converted from work to heat, or from potential to kinetic energy, help explain the ways we store and use energy, both in our bodies and in our electrical utility system. Further, a common problem in alternative energy production is that alternative energy sources are often more diffuse and difficult to capture than conventional sources, such oil or coal. Thermodynamics and energy transfers Thermodynamics is the study of how energy is transferred, its rates of flow and transformation from one form or quality to another. The first law of thermodynamics Energy of the universe is constant. Energy-mass cannot be created nor destroyed. Energy may be transformed, e.g. from a energy in a chemical bond to heat energy.  Second law of thermodynamics. When energy is converted from one form to another, some of the usable energy is converted to heat and is dispersed in the surroundings. At every step of energy transformation there is a loss of energy capable to do work. No one process that requires energy conversion is 100% efficient. All natural systems then to go from a state of order to toward a state of increasing disorder. Entropy or amount of disorder increases reflecting the loss of energy. There is less energy available at the end of a process than at the beginning. Sunlight: energy for life The sun is the ultimate source of energy for living organisms. A few ecosystems are based on energy derived from inorganic substances and the earth molten interior extremophiles are organisms that live in severe conditions Deep-sea hydrothermal vents provide energy to an ecosystem that lives in total darkness and under tremendous pressure. The energy source for this ecosystem is provided by inorganic molecules like hydrogen sulfide and hydrogen gas through a process called chemosynthesis. Most of these extremophiles are single celled organisms called archaea. Green plants get energy from the sun The sun produces warmth and light, both of which are needed for living organisms. Most organisms live within a narrow temperature range. Light is composed of particles of energy that travel as waves. Light is part of the electromagnetic spectrum, the entire range of electromagnetic radiation.  Of the solar radiation that reaches the earth’s surface, 45% is visible light, 45% is infrared radiation and 10% is ultraviolet radiation. 30% is reflected back into space. 20% is absorbed by the atmosphere. 50% is absorbed by ground, water and vegetation. Less than 1% of the absorbed energy is used in photosynthesis. This small percentage is the energy base for all life on the biosphere. How photosynthesis captures energy? Photosynthesis converts radiant energy into useful, high quality chemical energy in the bonds that hold together organic molecules (food!).  Photosynthesis is the conversion of light energy into chemical bond energy. It takes place in organelles called chloroplasts. 6CO2 + 6 H2O + solar energy → C6H12O6 + 6O2 light reactions of photosynthesis (make high-energy molecules of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate)) light-independent reactions (carbon dioxide is incorporated into small sugar molecules to make glucose, a high-energy sugar)  Cellular respiration releases chemical energy found in substances. The energy released is used by the cell to make biomolecules, e.g. proteins, lipids, etc., and to do cellular work, e.g. movement. C6H12O6 + 6O2 → 6CO2 + 6 H2O + energy released Photosynthesis captures energy; respiration releases energy. Energy and matter in the environment Living system are maintained by processes that capture energy from external sources and use it to carry out essential functions. Materials are used and recycled in these processes. Organization of living system: species, population, biological communities and ecosystem  Species – all organisms that are genetically similar enough to breed and produce live, fertile offspring in nature Population - consists of all members of a species that live in the same area at the same time biological community consists of all the populations living and interacting in an area. biological activity and its physical environment (water, mineral resources, air, sunlight) make up an ecological system, or ecosystem Much of ecology is concerned with understanding the ways energy and matter move through ecosystems. Food chains, food webs, and trophic level Photosynthesis is the base of the energy dynamics of an ecosystem Biomass refers to the amount of biological material produced in an ecosystem. productivity of an ecosystem is measured by the amount of biomass produced. The primary productivity of an ecosystem is the biomass produced by photosynthesis. The secondary productivity of an ecosystem is the biomass produced by organisms that eat plants or other organisms.  Food chain refers to the sequence of organisms in a community on successive trophic levels and through which energy is transferred. It is a feeding series (rarely more than four and five).  Food web – several interconnected network of food chain usually very complex involving hundreds of species.  Trophic level is the position of an organism in the food chain. Producers or autotrophs make food from simple organic matter. The largest group in a community. Consumers or heterotrophs obtain their food by eating other organisms. Primary consumers or herbivores eat plants. Secondary and tertiary consumers or carnivores eat other animals. Omnivores eat both plant and animal materials. Parasites, scavengers, detritivores and decomposers feed at all levels. Decomposers or saprobes feed on dead organisms and wastes.  Fungi and bacteria are decomposers and completer the final breakdown and recycling of organic materials. An ecological pyramid is formed when organisms in a community are arranged according to numbers. Producers are the most numerous and are placed at the base of the pyramid. The successive trophic levels decrease gradually. There are fewer deer than shrubs; less wolves than deer, etc. Ecosystem Characteristic 1. SELF-REGULATING = ability to maintain internal ecological balance = allows observation of the following: carrying capacity maximum sustainable yield waste assimilative capacity natural enemies  A species can indirectly affect the community and the physical environment through food chains. Changes in that group affect another group. Such indirect and complicated interactions are referred to as community-level interactions. Keystone species – a species that has a large effect on the community or ecosystem so that its removal or addition to the community leads to major changes in the abundances of many or all other species  Keystone species – a species (can be a predator) that has a large influence on the community or ecosystem so that its removal or addition to the community leads to major changes in the abundances of many or all other species Ex: Philippine eagle EXAMPLE: The sea otter is another example of a keystone species in the Pacific Northwest. These mammals feed on sea urchins, controlling their population. If the otters didn't eat the urchins, the urchins would eat up the habitat's kelp. Kelp, or giant seaweed, is a major source of food and shelter for the ecosystem. 2. Carrying capacity → maximum no. of individuals of a species that the habitat can support 3. Maximum sustainable yield → maximum limit of production that would still allow recycling of nutrients 4. Waste assimilative capacity → ability to take in and recycle waste4. 5. Natural enemies → maintain balance in ecosystem 6. Self-perpetuating → living components of the ecosystem have reproductive capability to allow species to continue existence → Organisms capability of reproduction leads to self-perpetuation of the species Biogeochemical Cycles is a pathway by which a chemical element or molecule moves through both biotic (biosphere) and abiotic (lithosphere, atmosphere, and hydrosphere) compartments of Earth. tells us that biological, geological and chemical factors are all involved. The circulation of chemical nutrients like carbon, oxygen, nitrogen, phosphorus, calcium, and water etc. through the biological and physical world are known as biogeochemical cycles. PHOSPHORUS CYCLE movement of phosphorus through the lithosphere, hydrosphere, and biosphere. the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth. Low concentration of phosphorus in soils reduces plant growth, and slows soil microbial growth - as shown in studies of soil microbial biomass.  ASSIGNMENT: Research the case of phosphate mining in Nauru and write your learning/reflection in a ½ sheet of paper. ECOLOGICAL FUNCTION Phosphorus is an essential nutrient for plants and animals. Phosphorus is a limiting nutrient for aquatic organisms. Phosphorus forms parts of important life-sustaining molecules that are very common in the biosphere. Eighty percent of the mined phosphorus is used to make fertilizers. Phosphates from fertilizers, sewage and detergents can cause pollution in lakes and streams. Enrichment of phosphate can lead to eutrophication of fresh and inshore marine waters, leading to algae blooms. HUMAN INFLUENCES Humans have greatly influenced the phosphorus cycle by: mining Phosphorus converting it to fertilizer by shipping fertilizer and products around the globe WATER CYCLE also known as the hydrologic cycle or the H2O cycle, describes the continuous movement of water on, above and below the surface of the Earth. involves the exchange of energy, which leads to temperature changes. figures significantly in the maintenance of life and ecosystems. HUMAN ACTIVITIES THAT ALTER THE WATER CYCLE INCLUDE: Agriculture industry alteration of the chemical composition of the atmosphere construction of dams deforestation and afforestation removal of groundwater from wells water abstraction from rivers urbanization NITROGEN CYCLE is the process by which nitrogen is converted between its various chemical forms. This transformation can be carried out through both biological and physical processes. Organism cannot exist without amino acids, peptides, nucleic acids, and proteins, all of which are organic molecules containing nitrogen N2 – stable diatomic molecules in the air which is cannot be used by plants IMPORTANT PROCESS IN THE NITROGEN CYCLE: FIXATION: occurs in lightning strikes, but most fixation is done by free- living or symbiotic bacteria. - process wherein N2 is converted to ammonium, or NH4+ - the few that can do this are called nitrogen-fixing organism - nitrogen fixing bacteria often form symbiotic relationships with host plant (e.g beans, peas, etc)  AMMONIFICATION: When a plant or animal dies, or an animal expels waste, the initial form of nitrogen is organic. Bacteria, or fungi in some cases, convert the organic nitrogen within the remains back into ammonium (NH4+), a process called ammonification or mineralization. NITRIFICATION - the conversion of ammonia to nitrate - primarily performed by soil-living bacteria and other nitrifying bacteria -Nitrosomonas species convert ammonia to nitrites (NO2-) - Nitrobacter are responsible for oxidation of the nitrites into nitrates (NO3-)  DENITRIFICATION - is the reduction of nitrates back into the largely inert nitrogen gas (N2), completing the nitrogen cycle. -This process is performed by bacterial species such as Pseudomonas and Clostridium in anaerobic conditions. HUMAN ACTIVITIES THAT ALTERED THE GLOBAL NITROGEN CYCLE: fossil fuel combustion use of artificial nitrogen fertilizers release of nitrogen in wastewater CARBON CYCLE is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere , geosphere, hydrosphere, and atmosphere of the Earth. Along with the nitrogen cycle and the water cycle, the carbon cycle comprises a sequence of events that are key to making the Earth capable of sustaining life; it describes the movement of carbon as it is recycled and reused throughout the biosphere. HUMAN INFLUENCE the industrial revolution -- direct emissions from burning fossil fuels, which transfers carbon from the geosphere into the atmosphere. Humans also influence the carbon cycle indirectly by changing the terrestrial and oceanic biosphere. SULFUR Sulfur (S), the tenth most abundant element in the universe, is a brittle, yellow, tasteless, and odorless non-metallic element. It comprises many vitamins, proteins, and hormones that play critical roles in both climate and in the health of various ecosystems. The majority of the Earth’s sulfur is stored underground in rocks and minerals, including as sulfate salts buried deep within ocean sediments.  Sulfur is a component of proteins, enzymes and other compounds. It is rarely a limiting nutrient and is usually absorbed as sulfate.  Ecology Matters Natural resource management = the application of ecological principles to the management of natural resources To manage biota, you have to understand ecology