Worksheet (6-9) for ecology lab


Table 6.2 – number of species present in the quadrant

  1. The quadrant size that there is no additional species added is 8 m2 (2.0 x 4.0) because that is the quadrant where the number of species starts to be the same and there are three consecutive similar number of species.
  2. It is a relationship between the area of a habitat, and the number of species found within that area. Larger areas tend to contain larger numbers of species, and empirically, the relative numbers seem to follow systematic mathematical relationships. It also shows the average number of species detected against the cumulative area sampled.

Table 6.3 – frequency of the individuals

  1. The species that has the highest frequency is the common grass. The root systems of grasses are highly branched and do not have a well-defined central taproot. The advantage of this grass is that it is very salt-tolerant. It can be irrigated with non-potable water, such as greywater, an important advantage when there are increasing restrictions on water use. The grass will be lower in quality than that irrigated with potable water, but it survives.
  2. The species that has the lowest frequency is makahiya. This plant is most often grown as an indoor annual, but is also grown for groundcover. Propagation is generally by seed. It grows most effectively in nutrient poor soil that allows for substantial water drainage. However, this plant is also shown to grow in scalped and eroded subsoils.

Table 6.4 – summary of species areas from quadrant sampling

  1. The species that has the largest area is the common grass. Grasses include some of the most versatile plant life-forms. Grasses have adapted to conditions in different habitats, and are now the most widespread plant type; grass is a valuable source of food and energy for all sorts of wildlife and organics.
  2. The species that has the lowest area is radish. Radishes are a fast-growing, annual, cool-season crop. The seed germinates in three to four days in moist conditions with soil temperatures between 65 and 85 °F. They can function as a trap crop, luring insect pests away from the main crop. Because their pungent odor deters such insect pests.
  3. The summary of importance value of the tree species in table 6.3 is:

Grass – The most important food crops are the grains of grasses such as wheat, rice, maize (corn) and barley.

Makahiya – All parts of the plant have been used to combat glandular tumors and uterine cancer.

Radish – It is a roughage and it is composed of indigestible carbohydrates. This facilitates digestion, water retention, and it fixes constipation.

Table 6.5 – calculations for quadrant sampling

  1. The species that has the highest importance value is common grass. Grass is an incredible survivor and is virtually indestructible. Because the roots will regenerate the plant when the tops are eaten, burnt, drowned, grass will survive drought, flood, fire and aggressive cropping. Grasses will survive and flourish in areas where there is insufficient rainfall to support trees
  2. The species that as the lowest importance value is radish. Radishes can be available year-around with peak season during winter and spring. As a fast-growing plant, diseases are not generally a problem with radishes, but some insect pests can be a nuisance.
  3. I therefore conclude that we can measure the plant abundance of the grassland by using the quadrant method. We also learned that plants make up the backbone of all habitats. Other species of fish and wildlife also depend on plants for food and shelter.



Table 7.1 – measurement of depth and amount of light penetration in the lake

  1. The light that is absorbed by the lake is 90.66%. Light provides the solar energy required to drive the process of photosynthesis, the major energy source of lentic systems. Green plants convert the light energy of the Sun into chemical energy through a process called photosynthesis.
  2. Factors that affect the light absorption in lake is (1) lakes may experience shading by surrounding trees, while cloud cover may affect light availability. (2) Seasonal and diurnal considerations also play a role in light availability because the shallower the angle at which light strikes water, the more light is lost by reflection. (3) Scattering of light in the water column. This scattering decreases the total amount of light as depth increases.

Table 7.2 – measurement of depth and amount of light penetration in lake

  1. The epilimnion or surface lake is the top-most layer in a thermally stratified lake, occurring above the deeper hypolimnion. It is warmer and typically has a higher pH and higher dissolved oxygen concentration than the hypolimnion. It is the part of a lake or ocean where the rate of photosynthesis is greater than the rate of respiration by phytoplankton.
  2. The hypolimnion or under lake is the dense, bottom layer of water in a thermally-stratified lake. It is the layer that lies below the thermocline. It contains no algae or phytoplankton, and its inhabitants are exclusively carnivorous animals or organisms that feed on sediment or detritus, all reliant on energy inputs from the euphotic zone.
  3. The metalimnion is a thin but distinct layer in a large body of fluid in which temperature changes more rapidly with depth than it does in the layers above or below. It divides the upper mixed layer from the calm deep water below. The thermocline varies in depth. It is semi-permanent in the tropics, variable in temperate regions (often deepest during the summer) and shallow to nonexistent in the polar-regions, where the water column is cold from the surface to the bottom. A layer of sea ice will act as an insulation blanket.

Table 7.3 – measurement of temperature

  1. Yes there is difference of 2.16oC between the temperature of the surface and bottom. Hypolimnion being at depth, it is isolated from surface wind-mixing during summer, and usually receives insufficient irradiance (light) for photosynthesis to occur. Epilimnion Being exposed at the surface, it typically becomes turbulently mixed as a result of surface wind-mixing. It is also free to exchange dissolved gases such as O2 and CO2 with the atmosphere. Because this layer receives the most sunlight it contains the most phytoplankton.
  2. The importance of temperature in the lake is Temperature is also important because of its influence on water chemistry. The rate of chemical reactions generally increases at higher temperature, which in turn affects biological activity. An important example of the effects of temperature on water chemistry is its impact on oxygen. Warm water holds less oxygen that cool water, so it may be saturated with oxygen but still not contain enough for survival of aquatic life. Some compounds are also more toxic to aquatic life at higher temperatures. Temperature is reported in degrees on the Celsius temperature scale (C).
  3. 2 factors affecting the temperature of the lake is. (1) Shade is very important to the health of a stream because of the warming influences of direct sunlight. Some human activities may remove shade trees from the area which will allow more sunlight to reach the water, causing the water temperature to rise. (2) Another factor that may affect water temperature is the temperature of the air above the water. The extent of its influence has a great deal to do with the depth of the water. A shallow stream is more susceptible to changes in temperature than a deep river would be.

Table 7.4 – measurement of TSS

  1. Yes there is 0.11 g of difference between the TSS of the surface and the bottom. The TSS of the bottom is higher than the surface water because some suspended solids can settle out into sediment at the bottom of a body of water over a period of time. The remaining particles that do not settle out are called colloidal or non-settle able solids. These suspended solids are either too small or too light to settle to the bottom and they are the ones that settle in the surface water.
  2. The importance of TSS in the lake is Turbidity is commonly used as an indicator for the general condition of the drinking water, but is an easy field water quality parameter to measure. Turbidity in water is caused by suspended matter such as clay, silt, and organic matter and by plankton and other microscopic organisms that interfere with the passage of light through the water. Turbidity is closely related to total suspended solids (TSS), but also includes plankton and other organisms.  Turbidity itself is not a major health concern, but high turbidity can interfere with disinfection and provide a medium for microbial growth. It also may indicate the presence of microbes
  3. The 2 factors affecting the TSS of the lake is (1) Soil Erosion – is caused by disturbance of a land surface. The eroded soil particles can be carried by storm-water to surface water. This will increase the turbidity of the water body. (2) High Flow Rates – The flow rate of a water body is a primary factor influencing turbidity concentrations. Fast running water can carry more particles and larger-sized sediment. Heavy rains can pick up particles from the land and carry it to surface water. A change in flow rate also can affect turbidity; if the speed or direction of the water current increases, particulate matter from bottom sediments may be re-suspended.



Table 8.1 – nitrogen, phosphorus, and hardness

  1. The main source of nitrogen compounds in water are fertilizers that mainly contain nitrate, but also ammonia, ammonium, urea and amines. Nitrogen itself is not hazardous when present in water, and therefore does not cause any environmental damage. In seawater nitrates, nitrites and ammonia are dietary requirements for plankton, causing nitrogen concentrations to be lower at the surface than in the deep. At increasing nitrogen concentrations in surface layers, plankton production increases, leading to algal blooms.
  2. Phosphorus occurs naturally in rocks and other mineral deposits. During the natural process of weathering, the rocks gradually release the phosphorus as phosphate ions which are soluble in water and the mineralize phosphate compounds breakdown.  Phosphorus is one of the key elements necessary for the growth of plants and animals and in lake ecosystems it tends to be the growth-limiting nutrient and is a backbone of the Kreb’s Cycle and DNA. Phosphorus is essential to the growth of biological organisms, including both their metabolic and photosynthetic processes.
  3. Hardness is caused by compounds of calcium and magnesium, and by a variety of other metals. Water hardness is important to fish culture and is a commonly reported aspect of water quality. It is a measure of the quantity of divalent ions such as calcium, magnesium and/or iron in water.  There are many different divalent salts; however, calcium and magnesium are the most common sources of water hardness.

Table 8.2 – measurement of salinity, conductivity, and TDS in lake

  1. The most important sources of salts, and therefore salinity, in all Earth’s waters are: (1) washing (dissolving) of salts from the soil and rock of the Earth’s crust; (2) precipitation (dust, rain and snow falling into the water) and (3) the evaporation and precipitation cycle. Salinity is also important for water uses on land by people and wildlife. The saltier the water, the more difficult and expensive it is to prepare for drinking, and the more dangerous it is to apply to crops.
  2. Total dissolved solids (TDS) is a measure of the combined content of all inorganic and organic substances contained in a liquid in molecular, ionized or micro-granular (colloidal sol) suspended form. The principal application of TDS is in the study of water quality for streams, rivers and lakes, although TDS is not generally considered a primary pollutant (e.g. it is not deemed to be associated with health effects) it is used as an indication of aesthetic characteristics of drinking water and as an aggregate indicator of the presence of a broad array of chemical contaminants.
  3. Conductivity is directly related to the concentration of ions in the water. These conductive ions come from dissolved salts and inorganic materials such as alkalis, chlorides, sulfides and carbonate compounds. Therefore, significant changes in conductivity can be an indicator that a discharge or some other source of pollution has entered the water. The composition of the water can be critical for aquatic organisms as well, as many critters have very specific ranges that they can tolerate.

Table 8.3 – measurement of pH and dissolved oxygen in the lake

  1. The pH of water determines the solubility (amount that can be dissolved in the water) and biological availability (amount that can be utilized by aquatic life) of chemical constituents such as nutrients phosphorus, nitrogen, and carbon) and heavy metals (lead, copper, cadmium, etc.).
  2. Yes there is 1.61 difference in the DO between the surface and bottom water of the lake. Aquatic organisms need oxygen to live. As water moves past their gills, microscopic bubbles of oxygen gas called dissolved oxygen (DO), are transferred from the water to their blood. In other words, oxygen can be present in the water, but at too low a concentration to sustain aquatic life. Oxygen also is needed for many chemical reactions that are important to lake functioning.
  3. 2 factors affecting the DO of the lake. (1) Dissolved oxygen concentrations may change dramatically with lake depth. Oxygen production occurs in the top portion of a lake, where sunlight drives the engines of photosynthesis. Oxygen consumption is greatest near the bottom of a lake, where sunken organic matter decomposes. (2) Seasonal changes also affect dissolved oxygen concentrations. Warmer temperatures during summer speed up the rates of photosynthesis and decomposition. When all the plants die at the end of the growing season, their decomposition results in heavy oxygen consumption.

Table 8.4 – measurement of primary conductivity

  1. The photosynthetic rate of the lake is 3.67 x10-3. If photosynthesis ceased, there would soon be little food or other organic matter on Earth. Most organisms would disappear, and in time Earth’s atmosphere would become nearly devoid of gaseous oxygen.
  2. The respiration rate of the lake is -0.06. Respiration in lakes recycles organic carbon arising from photosynthesis back to inorganic carbon. Prior to this transformation, the organic carbon is potentially available to support secondary production. The efficiency of primary and secondary production relative to respiration is an important feature of lakes and other aquatic ecosystems.
  3. The primary productivity of the lake is 0.06367. 2 factors affecting the primary productivity of the lake is (1) Land use – Levels of nutrients (nitrogen and phosphorus) and algae tend to be higher in lakes in pastoral catchments than in lakes in natural catchments. Because algal concentrations affect water clarity, the lakes in natural catchments have water that is clearer than water in lakes in pastoral catchments. (2) Lake depth – Deep lakes have a greater capacity to absorb incoming nutrients before showing definite signs of deterioration in water quality. The monitored lakes that have high levels of nutrients tend to be shallow. The monitored lakes with the lowest levels of nutrients are nearly all deep lakes

Table 8.5 – measurement of BOD5

  1. Yes there is a difference of 1.03 in the DO of the samples after 5 days. BOD is a common, environmental procedure for determining the extent to which oxygen within a sample can support microbial life. It is also important in waste water treatment, food manufacturing, and filtration facilities where the concentration of oxygen is crucial to the overall process and end products.
  2. When BOD levels are high, dissolved oxygen (DO) levels decrease because the oxygen that is available in the water is being consumed by the bacteria. Since less dissolved oxygen is available in the water, fish and other aquatic organisms may not survive. BOD value in polluted water is normally higher than the fresh water. Increased BOD can be resulted due to domestic sewage, petroleum residues and wastes of animals and crops.



Table 9.1 – total counting of planktons in the lake

  1. The species hat is the most abundant is Euglena and species C. Euglena serve as excellent bio-indicators of environment changes, not only by their presence or absence, but also by measuring the cellular changes that occur under differing environmental conditions. It is also able to photosynthesize, thus taking in carbon dioxide and releasing oxygen into the atmosphere so that other organisms can survive.
  2. The importance of planktons in the lake is Plankton are an important source of food for larger animals. Phytoplankton are the first link in the food chain. They are known as primary producers because they produce the first forms of food. Zooplankton and other small animals that graze on the phytoplankton are known as primary consumers. Phytoplankton are sometimes called the grasses of the sea. Like land plants, they produce lots of oxygen through photosynthesis. During photosynthesis they use the sun’s energy to combine carbon dioxide and water into simple foods. This process removes carbon dioxide from seawater and allows the water to absorb a lot of carbon dioxide produced in the atmosphere. This “global carbon cycle” helps regulate the temperature of our planet.

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