Biology 25

Information about Biology 25

Published on July 9, 2014

Author: JCKilapkilap



Freshwater Ecosystem : Freshwater Ecosystem PowerPoint Presentation: Freshwater is defined as having a low salt concentration — usually less than 1%. Plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (i.e., ocean). There are different types of freshwater regions PowerPoint Presentation: River River Ecosystem: River Ecosystem These are bodies of flowing water moving in one direction. Streams and rivers can be found everywhere — they get their starts at headwaters, which may be springs, snowmelt or even lakes, and then travel all the way to their mouths, usually another water channel or the ocean. The characteristics of a river or stream change during the journey from the source to the mouth. The temperature is cooler at the source than it is at the mouth. The water is also clearer, has higher oxygen levels, and freshwater fish such as trout and heterotrophs can be found there. Towards the middle part of the stream/river, the width increases, as does species diversity — numerous aquatic green plants and algae can be found. Toward the mouth of the river/stream, the water becomes murky from all the sediments that it has picked up upstream, decreasing the amount of light that can penetrate through the water. Since there is less light, there is less diversity of flora, and because of the lower oxygen levels, fish that require less oxygen, such as catfish and carp, can be found. PowerPoint Presentation: Viewed as a system operating in its natural environment and includes biotic interactions amongst animals, plants and micro-organisms, as well as abiotic physical and chemical interactions. River ecosystem are prime examples of lotic ecosystem. Lotic refers to flowing water, from the Latin lotus ,’’washed”. Lotic waters range from springs only a few centimetres wide to major rivers kilometres width. Light is important to lotic systems because it provides the energy necessary to drive Primary Production via Photosynthesis, and can also provide refuge for prey species in shadows it cast. The amount of light that a system receives can be related to a combination of internal and external stream variables. PowerPoint Presentation: Larger river systems tend to be wide so the influence of external variables is minimized, and the sun reaches the surface. Seasonal and diurnal factors might also play a role in light availability because the angle of incidence, the angle at which light strikes water can lead to light lost from reflection known as Beer’s law. Temperature- most lotic species are poikilotherms whose internal temperature varies with their environment, thus temperature is key abiotic factor for them. PowerPoint Presentation: Chemistry water chemistry between system varies tremendously. The chemistry is foremost determined by inputs from the geology of its watershed or catchment area but can also be influenced by precipitation and the addition of pollutants form human sources. Bacteria are present in large numbers in lotic waters. Free living forms are associated with decomposing organic material, biofilm on the surfaces of rocks and vegetation in between particles that compose the substrate and suspended in the water column. PowerPoint Presentation: Pond Pond ecosystem: Pond ecosystem An ecosystem is a dynamic complex of plant, animal, and microorganism communities and the non-living environment, interacting as a functional unit. Remember that the organisms living in an ecosystem are broken down into categories: producers, consumers, and decomposers. A pond is a quiet body of water that is too small for wave action and too shallow for major temperature differences from top to bottom. It usually has a muddy or silky bottom with aquatic plants around the edges and throughout. However, it is often difficult to classify the differences between a pond and a lake, since the two terms are artificial and the ecosystems really exist on a continuum. Generally, in a pond, the temperature changes with the air temperature and is relatively uniform. Lakes are similar to ponds, but because they are larger, temperature layering or stratification takes place in summer and winter, and these layers turnover in spring and fall. Ponds get their energy from the sun. As with other ecosystems, plants are the primary producers. The chlorophyll in aquatic plants captures energy from the sun to convert carbon dioxide and water to organic compounds and oxygen through the process of photosynthesis. Nitrogen and phosphorus are important nutrients for plants. The addition of these substances may increase primary productivity. However, too many nutrients can cause algal blooms, leading to eutrophication. PowerPoint Presentation: Producers • Phytoplankton, literally “wandering plants,” are microscopic algae that float in the open water and give it a green appearance . They carry out photosynthesis using carbon dioxide that is dissolved in the water and release oxygen that is used by the bacteria and animals in the pond. Phytoplankton are not actually plants-they are protists ! • Periphytic algae are microscopic algae that attach themselves to substrates and give the rocks and sticks a greenish brown slimy appearance. They also carry out photosynthesis and produce oxygen , often near the bottom of the pond where it can be used by decomposers. • Submerged plants grow completely under water • Floating plants include plants that float on the surface and plants that are rooted on the bottom of the pond but have leaves and/or stems that float. • Emergent plants are rooted in shallow water but their stems and leaves are above water most of the time. • Shore plants grow in wet soil at the edge of the pond. PowerPoint Presentation: Consumers • Zooplankton are microscopic animals that eat phytoplankton or smaller zooplankton. Some are single-celled animals, tiny crustaceans , or tiny immature stages of larger animals. Zooplankton float about in the open water portions of the pond and are important food for some animals. • Invertebrates include all animals without backbones. Macro invertebrates are big enough to be seen with the naked eye . Some of them are only found in clean water. • Vertebrates are animals with backbones. In a pond these might include fish, frogs , salamanders , and turtles. Decomposers Animal waste and dead and decaying plants and animals form detritus on the bottom of the pond. Decomposers, also known as detritovores , are bacteria and other organisms that break down detritus into material that can be used by primary producers thus returning the detritus to the ecosystem. As this material decomposes it can serve as a food resource for microbes and invertebrates. During decay microbes living on detritus can pull nutrients from the overlying water thus acting to improve water quality. In the process of breaking down detritus, decomposers produce water and carbon dioxide. Lake ecosystem: Lake ecosystem Life in a Lake Lakes and ponds can be structured into horizontal and vertical zones. In the nutrient-rich near the shore , aquatic life is diverse and abundant. Plants, such as cattails and reeds , are rooted in the mud underwater, and their upper leaves and stems emerge above the water. Plants that have floating leaves, such as pond lilies, are rooted here also. Farther out from the shore, in the open water, plants, algae, and some bacteria capture solar energy to make their own food during photosynthesis. T he types of organisms present in a pond or lake ecosystem depend on the amount of sunlight available. Some bodies of fresh water have areas so deep that there is too little light for photosynthesis. Bacteria live in the deep areas of the fresh water to decompose dead plants and animals that drift down from the land and water above. Fish adapted to cooler, darker water also live there. Eventually, dead and decaying organisms reach the bottom of a pond or lake , which is inhabited by decomposers, insect larvae, and clams. Animals that live in lakes and ponds have adaptations that help them obtain what they need to survive. Water beetles use the hairs under their bodies to trap surface air so that they can breathe during their dives for food. Whiskers help catfish sense food as they swim over dark lake bottoms. In regions where lakes partially freeze in winter, amphibians burrow into the littoral mud to avoid freezing temperatures . PowerPoint Presentation: How Nutrients Affect Lakes is an increase in the amount of nutrients in an aquatic ecosystem. A lake that has a large amount of plant growth due to nutrients is known as a eutrophic lake. As the amount of plants and algae grows , the number of bacteria feeding on the decaying organisms also grows. These bacteria use the oxygen dissolved in the lake’s waters . Eventually, the reduced amount of oxygen kills oxygen loving organisms. Lakes naturally become eutrophic over a long period of time. However, eutrophication can be accelerated by runoff . Runoff is precipitation, such as rain, that can carry sewage, fertilizers , or animal wastes from land into bodies of water. Life Zones in a Lake or Pond: Life Zones in a Lake or Pond Depend of the amount of sunlight available • Littoral Zone – nutrient-rich, near shore, aquatic life is diverse and abundant. • Plants, such as cattails and reeds are rooted in the mud underwater, and their upper leaves and stems emerge above the water. • Plants with floating leaves, like pond lilies, are also rooted here. • Many fish live here as there is good hiding and food in the plants. PowerPoint Presentation: Limnetic Zone – well-lit, open surface waters, away from the shore • Further out from the shore in the open waters there are other plants, algae, and some bacteria that make food through photosynthesis. • Many fish swim freely in this zone. • Algae, phytoplankton, and zooplankton live (float freely) here as well. • Most photosynthesis occurs in this part of the lake. • Near the surface there is plenty of light penetrating down through the waters. As waters deepen it becomes darker PowerPoint Presentation: Profundal Zone (aphotic zone) – deeper open waters away from shore, colder and darker zone • located below the range of light penetration – so little to no light. • Temperatures typically colder (because sunlight does not penetrate) • Fish adapted to live in darker, cooler water live here. PowerPoint Presentation: • Benthic Zone – bottom of a pond or lake, predominately inhabited by decomposers, insect larvae, and clams. • Sometimes little to no light, depending on the depth. • Bacteria live here to decompose dead plants and animals that drift down from the land and water above. • Fish adapted to live in darker, cooler water also live here. Wetlands: Wetlands Freshwater wetlands – areas of land covered with freshwater for at least part of the year. • Are identified based on their water, soil types (hydric soils), and vegetation. • Water typically floods the areas consecutively for at least 7.5% of the growing season. • Hydric soil (wetland soils) remains wet long enough to create oxygen –poor conditions. • Plants in wetlands are hydrophilic – adapted to growing in wet soil with little oxygen. • Wetlands are important environmental functions that are needed to help protect our land and water sources. Important Environmental Functions: Important Environmental Functions They improve water quality of lakes, reservoirs, and rivers • Wetlands act as filters or sponges – they absorb and remove pollutants from the water that flows through them. • They control flooding by absorbing extra water when rivers overflow. (protecting farms, urban, and residential areas from damage) • Provide feeding and spawning grounds for fish • Provide home for native and migratory wildlife, including blue herons • Wetland vegetation traps carbon (that would otherwise be released as carbon dioxide into the atmosphere) • Buffering shorelines against erosion PowerPoint Presentation: Freshwater Wetlands Two main types of freshwater wetlands: • Marsh – contains non woody plants, such as cattails • Swamps – dominated by woody plants, such as trees and shrubs

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