Lecture 2-Water as an Environment PDF

MAFS 110: Aquatic Resources for Food and Livelihoods Lecture 2: Water as an Environment for Living and Non-living Resources Dr. Sam Addo Dr. Eunice K. Asamoah Dr. Andy Agyekumhene  Water Is Life Three-quarters of Earth’s surface is cover...

MAFS 110: Aquatic Resources for Food and Livelihoods Lecture 2: Water as an Environment for Living and Non-living Resources Dr. Sam Addo Dr. Eunice K. Asamoah Dr. Andy Agyekumhene  Water Is Life Three-quarters of Earth’s surface is covered by water. Although most of this water is in liquid form, water is also present on Earth as a solid (ice) and a gas (water vapor). Water is the only common substance to exist in the natural environment in all three physical states of matter. Furthermore, the solid state of water floats on the liquid, an anomaly emerging from the chemistry of the water molecule.  Water Is Life What is peculiar about the planet Earth? All the biochemical processes which occur in plants and animals, our surroundings, etc. require water to function. It is required for the existence of life on earth as it is an essential component of all the biological processes. Lives without the presence of water? The abundance of water is a major reason Earth is habitable  Water Chemistry Water molecules are made of two hydrogens and one oxygen. These atoms are of different sizes and charges, which creates the asymmetry in the molecular structure and leads to strong bonds between water and other polar molecules.  How is water important to Life? The bonding makes water molecules stick together in a property called cohesion. The cohesion of water molecules helps plants take up water at their roots. Cohesion also contributes to water’s high boiling point, which helps animals regulate body temperature. The capability of water to dissolve a variety of molecules has earned it the term “universal solvent,” and this ability makes water an invaluable life-sustaining force. On a biological level, water's role as a solvent helps cells transport and use substances like oxygen or nutrients, drugs etc.  Water impacts cell shape Water creates pressure in the cell that helps it maintain shape. In the hydrated cell, the water pushes outward and the cell maintains a round shape. In the dehydrated cell, there is less water pushing outward so the cell becomes wrinkled. Water also contributes to the formation of membranes surrounding cells.  Chemical reactions of water Water is vital for all life. Its versatility and adaptability help perform important chemical reactions. No other molecule matches water when it comes to unique properties that support life. Water acts as a buffer by releasing or accepting hydrogen atoms Earth’s water  The Hydrologic Cycle Water is an environmental resource without which, nothing can survive. It is an essential, renewable resource that occurs naturally on Earth. Water is constantly being recycled through the atmosphere, rivers and oceans in a natural system known as the water/hydrologic cycle The Hydrologic Cycle  Water as an environment Water is the environment/habitat for aquatic lifeforms. In general, there are two types of aquatic ecosystem: – Marine ecosystems – Freshwater ecosystems. Both marine and freshwater ecosystems are further divided under different aquatic ecosystems; – Aquifers and springs (Groundwater) – Rivers and streams – Lakes and ponds – Wetlands – Lagoons and estuaries. – Ocean  The aquatic ecosystem supports aquatic plant growth provides a permanent dwelling for animals provides a temporary habitat or breeding ground for amphibians, insects and other organisms provides the nutrients and minerals necessary to sustain aquatic life. provides food and wealth to sustain livelihoods (fish, gold, diamond, petroleum etc) and build a nation Varieties of aquatic lifeforms Varieties of aquatic lifeforms  Pistia stratiotes (Water Lettuce) Nymphaea lotus (Water Lily)  Oryza longistaminata (Longstamen rice) Vossia cuspidata (Hippo grass)  Ceratophyllum demersum (Coontail) Typha domingensis  Phragmites australis (common reed) Cyperus papyrus (papyrus sedge)  Biotic and Abiotic factors Ecosystems, such as oceans, rivers, and lakes, sustain themselves through the flow of energy and matter between the biotic and abiotic factors. Biotic factors are the living elements in an ecosystem There are three main groups: – Producers – consumers (herbivores, carnivores and omnivores) – decomposers.  Abiotic Factors Major factors that determine where organisms live in water include: Light/sunlight Temperature Oxygen Nutrients pH Temperature = active zz z = z z z inactive Fish gasping for oxygen