Introduction to Ecology 2024 PDF

An Introduction to Ecology Env.E. 101 Fall 2024 Outline Ecology and ecosystems Energy flow in ecosystems Pollution in Aquatic Environments Ecology Ecology – science dealing with interactions between organisms and the environment – These interactions determine dis...

An Introduction to Ecology Env.E. 101 Fall 2024 Outline Ecology and ecosystems Energy flow in ecosystems Pollution in Aquatic Environments Ecology Ecology – science dealing with interactions between organisms and the environment – These interactions determine distribution of organisms and their abundance – Plants and animals in their physical and chemical environment make up an ecosystem. Ecosystems Ecosystems are communities of organisms that interact with one another and with physical environment including sunlight, rainfall, and soil nutrients as well as chemical environment. Ecosystem is somewhat more technical term for “nature”. Structure of Ecosystem Abiotic components: Non-living things Biotic components: Living things Structure of Ecosystem Biotic components: Primary producers – Plants, algae etc. (autotrophs) All convert light energy into metabolic energy Consumers – Primary, secondary etc. (Macro consumers) (heterotrophs) Primary consumers (herbivores) feed on primary producers (Plant eaters). Higher organisms are carnivores (meat eaters). Decomposers – bacteria, fungi (Micro consumers) (heterotrophs) They break down the dead bodies (detritus) and release simple substances usable by the producers.  © 2011 Cengage Learning Engineering. All Rights Reserved. Source: Introduction to Environmental Engineering SI; Vesilind, Morgan, Heine Pyramid Effect Structure of Ecosystem Abiotic components: Inorganics – Nutrient elements C, H, N, S, O, P, Mg, K, Na etc. Recycle in the environment and are available to biotic components. Organics – Cellulose, lignin, proteins, carbohydrates, lipids etc. Physical Conditions – Temperature, pH, currents etc. Ecosystems Ecosystems are continually regulated by checks and balances. i.e. there are forces and counterforces in order to compensate every phenomena. e.g. CO2 remains fairly constant in the biosphere thanks to green plants utilizing this gas. CO2 fixed by plants is oxidized back to CO2 (by fossil fuel combustion) Ecosystems Ecosystems are continually regulated by checks and balances. i.e. there are forces and counterforces in order to compensate every phenomena. e.g. CO2 remains fairly constant in the biosphere thanks to green plants utilizing this gas. CO2 fixed by plants is oxidized back All living systems to resist change and to to CO2 (by fossil fuel remain in a state of equilibrium. But, human combustion) upset the balance… Ecosystems function thru: 1. Energy flow between trophic levels 1. Recycling of nutrients (mass flow) Energy and Trophic Levels – Part of sun energy hits the surface of the earth – Of this, 1-2 % is converted to useful metabolic energy Energy and Trophic Levels Thermodynamic Law: 1. You cannot create or destroy energy but you can only transfer it from one form to another 2. During transfer or conversion, a portion will be lost as heat. The rest will be available for work. – Part of sun energy hits the surface of the earth – Of this, 1-2 % is converted to useful metabolic energy  Energy flow in a food chain Sun (e.g. 1000 J) The transfer of 98% energy lost food energy from (e.g. 7 J maintenance) Producer (e.g. 12 J) (e.g. 5 J new tissue) plants, ultimately to higher animals 90% energy lost by way of eating Primary consumer (e.g. 0.5 J) and being eaten. 90% energy lost Secondary consumer (e.g. 0.05 J) 90% energy lost Tertiary consumer (e.g. 0.005 J)  © 2011 Cengage Learning Engineering. All Rights Reserved. Energy flow in a food chain Source: Introduction to Environmental Engineering SI; Vesilind, Morgan, Heine Energy Flow in Ecosystems (via Food Chain) The flow of energy maintains order and life. Ecosystems maintain a high state of internal order or a condition of low entrophy. For example: an animal takes in chemical potential energy for food, large part of this energy is dissipated and a small fraction (10%) is converted into new protoplasm. Roles of Organisms Organisms can be either producers or consumers in terms of energy flow through an ecosystem. Producers convert energy from the environment into carbon bonds (plants, algea, deep-sea bacteria) (autotroph) Consumers get their energy from the carbon bonds made by the producers (heterotroph) Bioaccumulation and Biomagnification Bioaccumulation build up of substances (e.g. DDT) in the tissues of organisms Biomagnification cumulative build up of substances sequentially through a food web by a series of bioaccumulation Food chain & food web Biomagnification of DDT in a Marine Ecosystem (0.04 ppm) Source: Introduction to Environmental Engineering SI; Vesilind, Morgan, Heine World War II - DDT It was used in the second half of World War II to control malaria and typhus among civilians and troops. DDT Paul Hermann Müller was DDT is an effective pesticide given 1948 Nobel Prize in medicine for his discovery DDT was used for about 20 years, of the high efficiency of then banned DDT as a contact poison But, the body of every people still has against several insects" DDT Agricultural pesticides… Arsenic and other chemicals had also been used as agricultural pesticides Mercury, cadmium may also accumulate As a result of high concentration of chemicals, many bird populations are going extinct. The greater the biodiversity, the greater stability in ecosystem PP1 X PP2 PP3 PP4 … Recycling of Nutrients in Ecosystems Biogeochemical cycles Living organisms require 30-40 elements Finite supply Utilization of these needs to be compansated Cycles make the elements available for reuse by transforming and recirculating them thru atmosphere, hydrosphere, litosphere and biosphere. Biogeochemical cycles Types: Gaseous nutrient cycles Sedimentary nutrient cycles Gaseous nutrient cycles Nutrient reservoir : the atmosphere There is little or no loss of the nutrient element. Typical cycles: “C, O, N” cycles Sedimentary nutrient cycles Nutrient reservoir : sedimentary rocks Considerable loss of the nutrient elements (sedimentary loss in deep-sea) Typical cycles: “P, S” cycles  Carbon Cycle CO2 in the air Respiration Respiration Photosynthesis Respiration Decomposers Death Plants Death Animals Eating Nitrogen Cycle 79% of the atmosphere is made up of nitrogen gas Nitrogen is essential for all N2 organisms to make very few organisms can proteins extract it from the air Nitrogen Cycle N2 Photochemical, industrial Biological fixation fixation Eating NO3- Death and decay Denitrification NO3-  Phosphorus Cycle P is a vital component P is essential for all of organisms DNA, RNA & ATP Phosphorus Cycle  Sulphur Cycle S is a vital part of protein (-SH-thiol group) Both gaseous and soluble forms S is essential for all organisms Sulphur Cycle  © 2011 Cengage Learning Engineering. All Rights Reserved. Water Cycle Water budget P=I+E+T+R Source: Introduction to Environmental Engineering SI; Vesilind, Morgan, Heine