Ecology

1. Ecology Reinaldo Gutiérrez Ana Ramirez

2. How do abiotic factors and biotic factors affect population size in an ecosystem? Biotic factors such as competition, emigration, and immigration play a vital role in the carrying capacity and population size in an ecosystem, since when populations reach a certain size individual species in a ecosystem compete for limited resources, such as food, and water which limits the population size in a community and therefore plays a vital role in its carrying capacity of a community, and during emigration some organisms live a ecosystem decreasing its population, ,and during immigration a new organism is introduced increasing the size of the population. Abiotic factors such , the amount of water, and sunlight available in a community also drastically affect a community since when resources become depleted due to abiotic factor such as a drought , many species compete for the few remaining resources left in their environment, whichas a result drastically decreases the population size in a ecosystem when resources are limited, however when resources are plentiful, population sizes, begin a period of exponential growth, until they reach their carrying capacity, at that point where the competive exclusion principle takes a toll in the population size due to competition, and many other abiotic factors, and many other abiotic factors.

3. What are the different types of organisms within an aquatic ecosystem? • The aquatic ecosystems contain a biodiversity of life on planet earth, since it covers seventy-five percent of our planet. The aquatic systems are divided into two parts the photic zone (200 meters at its deepest), where photosynthesis can occur, and the aphotic zone where photosynthesis cannot occur, but instead chemosynthesis takes a part in providing its great diverse deep underwater ecosystems. Photosynthetic algae called phytoplankton, and zooplankton live in the photic zone. There are however organisms called benthos who live near the bottom of aquatic ecosystems in a place called the benthic zone, where the water is shallow enough to allow benthos to be in the photic zone, algae, and rooted plants can grow, When the benthic zone is below the photic zone however, chemosynthetic autotrophs are the only primary producers.

4. Freshwater Ecosystems. • Freshwater ecosystems include rivers and streams, lakes and ponds, and freshwater wetlands. Even though rivers and streams contain a great amount of dissolved oxygen, they do not contain a great diversity of plants, and animals in these ecosystems depend on terrestrial plants, and animals that live along their banks for food, as downstream sediments build up plants establish themselves. Lakes and ponds contain ecosystems with food webs mainly depend on plankton ( zoo, and phytoplankton), attached algae, and plants. Water circulates in and out of lakes and ponds and circulates between the surface and the benthos during some seasons, providing heat oxygen, and nutrients. Wetlands are very often energy rich and highly productive providing a breeding ground for many organisms. Wetlands have an important role in the environment purifying water by filtering pollutants and help in prevent flooding by absorbing large amounts of water, and slowly releasing it. The three main types include freshwater bogs, freshwater marshes, and freshwater swamps.

5. Estuaries. • Estuaries are a special kind of wetland formed where a river meets the sea, containing a mixture of freshwater and saltwater. Many estuaries are shallow allowing enough sunlight to reach the benthos so photosynthesis can occur. Although support an outstanding amount of biomass, they contain fewer species than freshwater, or marine ecosystems, making them commercially valuable. Estuaries serve as nursery grounds for many ecologicallly and commercial important fish, such as bluefish, stripped bass, shrimp, and crabs.

6. Marine ecosystems. • Ocean ecosystems are divided vertically into zones based on light penetration and depth, and horizontally into zones based on distance from the shore. The shallowest and closest to land include the intertidal zone, the coastal, and the open ocean. Organisms in the intertidal zone are exposed to regular and extreme temperature changes, as well as they are battered by waves, and currents, yet many marine ecosystems are found in the intertridal zone. Coastal communities include coastal reefs and are highly productive , and water is brightly lit, and is supplied with nutrients by freshwater runoff from land. Open ocean includes 90 percent of the worlds ocean area, ranging from 500 to 10,00 meters, divided into the open ocean photic zone, and aphotic zone. In the open ocean photic zone low nutrient levels are found, and the smallest species of phytoplankton live, but it still contains the most photosynthesis in earth in its first 100 meters. The open ocean aphotic zone is the deepest part of the ocean based mostly on chemosynthetic organisms, but organisms are exposed to frigid temperatures, high pressure, and total darkness, yet are highly productive. The amount of salinity in different areas of the ocean also affects the different organism that live there, since the more salinity in the water the colder it is and the different organisms that live in it for example organism in the intertidal zone such as whales that live in the photic zone and receive more sunlight than organisms than organisms that live in the open ocean where the water temperatures are much colder since the sun’s rays do no penetrate that far down in the ocean, and there is a higher level of salinity since the water temperature is much colder, so therefore depending on how deep in the ocean organisms live the more salinity there is and the colder the temperature it is as well, and the different organisms that live there as well.

7. Potential changes to an ecosystem resulting from seasonal changes, climate changes, and or succession. • Seasonal changes, climate changes ,and succession can potentially alter an ecosystem in a variety of ways. Seasonal changes can drastically affect an ecosystem because since every seasonal change there are different resources that are being added and being removed from an ecosystem, and energy consumption and resources are depleted depending on the season drastically affecting the way animals live and how they search for the resources they need for survival, in other words the niche of the organism is altered, as well as its tolerance under certain seasonal changes stress. • Climate just like seasonal changes can drastically affect an ecosystem. If they year after year pattern of temperature and precipitation begin to slowly change overtime these minor changes can drastically alter the lives and niches of organisms in an ecosystem since they have to adapt to the new environmental conditions year after year after they have been adapted to the other climate conditions in which they thrived in, and if serious climate alterations begin taking place overtime their environment, overtime many species will begin to become endangered and extinct if they do not adapt to the environmental exposed stress and conditions. • Succession can alter an ecosystem just like seasonal and climate changes, since succession can alter an ecosystems original environmental condition by the immigration a pioneer species after the environment has been partially disturbed as in secondary succession , or it can be restored to its original conditions , and in some cases it may never recover. However another kind of succession primary succession unlike secondary may bring about the conditions for a new ecosystem to begin and grow over long periods of time, after new landscape has been exposed, and since there's no trace of an existing community in the place where primary succession began. In other words succession can change an ecosystem in a variety of ways it can introduce new species by immigration or emigration through secondary succession after the introduction of a pioneer species to that partially disturbed habitat, it can be restored to its original conditions over time, or it may not recover and remain barren and desolated, or it might introduce new communities, and eventually new ecosystems through primary succession.

8. Examples of what causes a reduction in biodiversity. • Catastrophic events such as tsunamis, volcanic eruptions, and earthquake contribute to reduction in biodiversity since these catastrophic events contribute to death toll of many species worldwide, thus reducing the biodiversity of species that the earth provides. • Climate changes such as global warming are another major problem that needs to be addressed since it constantly causes the increase of global temperature throughout the world at a steady rate of approximately 1 degree per year having a drastic effect on the melting of the polar ice caps which in turn has killed many species living in certain ecosystems in the poles due to the changing climate worldwide in which animals have to change their behavior and adapt to this pattern of change which can in turn cause major consequences in ecosystems worldwide as animals try to adapt to these major climate changes, such as the yellow bellied marmot which is coming out of hibernation one month earlier, in response to the rising temperatures. • Invasive and nonnative species which may be introduced by humans or may travel to a certain ecosystem just by chance can have a drastic effect on the biodiversity in that ecosystem. For example goats introduced by humans when they traveled to the Galapagos islands on their voyages into the island caused a drastic effect on the biodiversity on certain types of tortoises, that they either become extinct or are in danger of becoming extinct since the goats introduced by humans ate all the plants that the tortoises ate on the island, and when the plants began decreasing in population, so did the different varieties of Galapagos tortoises since they depend on these plants for food, and when the food became scarce due to the goats eating themthe tortoises became scarce as well, since they depended on these plants for food.

9. Pros and Cons resulting from a reduction in biodiversity. • The pros are that a reduction in biodiversity provides for human comfort and desires such as more land and better homes to live in, agriculture, communication, and the advancement in the benefits of human life, as time progresses, and new innovations, and technology in general, as we clear more land through deforestation to provide for human needs and comfort the world experiences the ever-growing human population transition to a better suited comfort for our own benefit, from the lives we lived in the past. • The Cons about reduction in biodiversity is that as we enjoy the comfort that we receive from a reduction in biodiversity we do not realize that as we benefit we are also damaging our environment and ourselves. For example, as we keep clearing out forests for land and agriculture, we do not realize that we are disturbing the balance of nature and we are constantly losing the precious biodiversity that earth provides, which we can use to benefit ourselves further since each species is unique, and it provides certain traits that others do not which can only assist us in the advancement in the medical field, in our search for cures to various diseases, and if we lose that biodiversity, we may never discover that treatment or cure, that will only help alleviate our pain and discomfort. Anyways besides the medical field if we keep clearing out forests for land we may lose many trees that are only assisting us in removing harmful toxics and pollutants that we put in the atmosphere through the use of automobiles that burn fossil fuels releasing harmful pollutants into the atmosphere, besides trees and plants in general are essential through our survival since they absorb carbon dioxide in the atmosphere and transform into oxygen which they release into the atmosphere which we use in order to breathe, and to remain alive. • In other words a reduction in biodiversity can be more harmful, than it can be beneficial to human beings.

10. Human impacts in the loss of biodiversity. • Humans are the main reason that we are experiencing a major loss in biodiversity. Humans have a major effect on the nitrogen cycle, carbon cycle, and phosphorus cycle. Humans impact the carbon cycle by releasing carbon in the form of carbon dioxide by burning fuels faster than carbon absorbing plants can absorb all that carbon which eventually accumulates in the atmosphere creating a greenhouse which traps large amounts of solar energy, which eventually accumulates overtime increasing the global temperatures by 1 degree yearly, which in turn melts the polar ice caps, reducing the biodiversity in the poles and around the world as many species attempt to adapt to this changing climate (global warming). Humans impact the phosphorus cycle by moving phosphorus around and it becomes runoff, and once it is in runoff in can end up in large bodies of water resulting in eutrophication to occur killing many animals in the water. Other sources of phosphate in aquatic systems include outflow from sewage treatment facilities and runoff of animal waste from livestock feedlots, resulting in heavy growth in algae and cyanobacteria, which consume a great deal of oxygen as they decompose the extra, depleting the water of dissolved oxygen, leading to reduced species diversity. Humans impact the nitrogen cycle by using nitrogen-containing fertilizers in agriculture, under certain conditions in which agricultural plants have access to as much water as they require , their productivity is usually constrained by the rate at which they can obtain nitrogen available forms, such as nitrate. Under these conditions farmers attempt to increase the availability of nitrogen by applying fertilizers. By dumping sewage and other types of organic matter into water bodies, which damages the environment by lowering dissolved oxygen levels related with microbial oxidation of the organic matter, and the presence of pathogens and parasites. Accidental fertilization of water bodies with large quantities of nitrogen contribute to eutrophication.

11. Other humans impacts leading to loss of biodiversity. A ph scale used to measure the concentration of hydrogen ions in a substance such as Dichlorodiphenyl-Tricholoroacetic Acid (DDT) released by humans into the environment can be vital to the survival of many species that take up this compound into their body systems, and the higher trophic level this component reaches in a food pyramid the more harmful it can be to consumers atop the food pyramid since they have a much higher concentration of DDT than producers in bottom of the food pyramid since every time these components are passed on from one consumer to the next the next this acidic component is stored in their systems in a much higher concentration, that can lead to birth defects of their offspring. For example eagles at the top of a food pyramid that have high concentration of DDt may lay leg thin eggs that may result in the death of its offspring before it is even born, this overtime may lead to a decrease in biodiversity, since it is very harmful to many species at a higher concentration, which eventually affects the balance of nature because the organism that these predators eat become abundant since there is less predators to capture them, and as a result they eat more of the primary producers, leading to a huge loss of biodiversity.