Ecology and Environment Notes Part 3 – Coral Reefs, Biomes, Community and Population

  • Post category:Environment

Coral Reefs

  • Coral is a plant-animal superorganism, an alga called zooxanthellae, grow inside the tissues of the animal polyp, thus exhibits mutualism between polyps & algae
  • Located generally between 30 degrees North and 30 degrees South latitudes.
  • Found scattered in coastal zones above continental shelves throughout the tropical and subtropical western Atlantic and Indo-pacific oceans.
  • The polyp can feed itself using stinging cells found on its tentacles but is able to feed itself partially. The remainder comes from the zooxanthellae and the carbohydrates are also used by the polyp to make calcium carbonate via calcification. This material forms the skeleton of the coral and eventually the framework known as the coral reef.
  • Polyps secrete hard limestone deposits (calcium carbonate that remains when polyps die. • Coral reefs are sometimes referred to as ‘tropical rainforests of the deep’.
  • Bleaching: Under environmental stress, much of the algae are lost and corals appear white in colour. If the symbiotic green algae leave the coral animal and the mutualism is not restored, then the coral slowly dies of starvation. Importance of Coral reefs
  • Apart from tropical rainforests, they are the other most productive natural ecosystems in the world.
  • They protect the coastline from storms & high waves by breaking the force of the waves, thereby allowing mangroves and seagrass to flourish.
  • They serve as nurseries for many fish species and provide resources for fisheries.
  • Coral skeletons are being used as bone substitutes in reconstructive bone surgery. The pores and channel in certain

Importance of Coral reefs

  • Apart from tropical rainforests, they are the other most productive natural ecosystems in the world.
  • They protect the coastline from storms & high waves by breaking the force of the waves, thereby allowing mangroves and seagrass to flourish.
  • They serve as nurseries for many fish species and provide resources for fisheries.
  • Coral skeletons are being used as bone substitutes in reconstructive bone surgery. The pores and channel in certain corals resemble those found in human bone. Bone tissue and blood vessels gradually spread into the coral graft. Eventually, bone replaces most of the coral implant.

Terrestrial Ecosystem

Biomes can be defined as major ecological communities of flora and fauna, which generally extend over a large part of the earth surface and usually characterized by a distinct type of vegetation.

The main terrestrial biomes are:

  • Tundra
  • Coniferous forests/Temperate evergreen forests
  • Temperate Broadleaf deciduous forests
  • Mediterranean Shrublands
  • Grasslands
  • Deserts
  • Tropical deciduous forests
  • Tropical shrubs/Thornwood
  • Tropical rainforests
  • E elements and V.E Shelford (1939) introduced the biome concept.
  • Ecotone: the boundary between two biomes.
  • Bailey (1976) developed the concept of the ecoregion.
  • Ecoregions: Ecosystems based on a continuous geographical or landscape area across which the interactions of climate, soil and topography are sufficiently uniform to permit the development

Community

A group of the population of distinct species living together in a given area with mutual tolerance and beneficiary interactions is defined as a community. The species may be plant, animal or microorganism.

Characteristics:

  • Biodiversity
    • Species richness
    • Relative abundance
  • Dominant vegetation
  • Stability/disturbance
  • Succession

Population

A population is a summation of all the organisms of the same group or species, which live in a particular geographical area, and have the capability of interbreeding. Population Dynamic is the change in the number of individuals in a population or the vital rates of a population over time. It is the key to

  • Examine the response of species to ecosystem manipulation,
  • Analyzetheendangered species
  • Understand ecosystem dynamics and ecology

Theories of Population Dynamics

  • Exponential population growth is when the birth rate is constant over a period and isn’t limited by food or disease. A species growing exponentially would also affect other species directly due to competition for food and other resources. Exponential growth can be affected by modern medicine, quality and quantity of food and the overall standard of living for a species.
  • Logistic growth describes a sustainable growth of populations which slows down after a period of significant development as the availability of living space and resources, along with other factors, limits its growing ability. The logistics growth model is a more reliable measure of population growth than the exponential model because it accounts for the real-world factors that inhibit population growth.

 

Organism

An organism is any form of the contiguous living system such as an animal, plant or bacterium with the cell as its basic units. All organism has developed with some degree of response to stimuli, reproduction, growth and development and homeostasis. As the basic unit of every organism is cell it can be categorized into both unicellular and multicellular depending upon the no. of cells present in the organism. Mostly the unicellular organisms are microscopic by nature. Biodiversity means diversity or heterogeneity at all levels of biological organization, i.e., from macromolecules of the cells to the Biomass. The term Biodiversity was popularized by the sociologist Edward Wilson.

The important levels of biodiversity are

  • Genetic diversity
  • Species diversity
  • Ecological diversity

Genetic diversity

It is the diversity at the genetic level, or at subspecies level, i.e. below the species level, in a single species. The genetic diversity helps the population to adapt. If a population has more diversity it can adapt better to the changed environmental conditions. The low diversity leads to uniformity. The genetic variability is, therefore, considered to be the raw material for speciation.

Species diversity

The measurement of species diversity is its richness, i.e. the number of species per unit area. The greater is the species richness the more will be the species diversity. In nature, the number and kind of species, as well as the number of individuals per species, very, and this leads to greater diversity.

Ecological diversity

It is the diversity at the community level. It can be of 3-types

  • Alpha (α) diversity: It is the diversity of organisms within the same community or habitat.
  • Beta (b) diversity: It is the diversity of communities or different habitats. Higher the heterogeneity in the altitude, Humidity and Temperature of a region, the greater will be the dissimilarity between communities, and higher will be the β diversity.
  • Gamma (γ) diversity: It is the diversity of organisms over the entire geographical area, covering several ecosystems or habitats and various trophic levels and food webs. Such diversity is most stable and productive.

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