Thursday, November 25, 2010



            Situated close to the Shaganappi-John Laurie intersection in the Northwest of Calgary in the province of Alberta, Canada, Nosehill Park is a grassland dominated area situated amidst an urban environment surrounded on all sides by residential communities. The park is approximately 11.3 km2 in area and comprises of various ecosystems such as the grassland ecosystem, the forest ecosystem and the pond ecosystem.

Figure 1. Storm water reteinton pond at Nose Hill.
Taken by Pawan on October 10, 2010

          The pond ecosystem at Nosehill Park is presently a storm-water retention pond.  8 years ago, the City of Calgary unveiled a project that would move the hill on the Northern side of the pond to the Southern side of the pond. This would in turn allow storm runoff to flow into the pond from high-level areas in Edgemont. Over the years, the ecosystem in the pond has changed drastically. Chemicals in the pond that were present in mild concentrations began to accumulate to form large quantities, native species populations in the pond ecosystem began to decrease only to be replaced by populations of non-native species and direct human activity on the pond was on the incline as well.

 - background information that relates to how human activity has affected biological life in and around the pond ecosystem at Nosehill Park. More specifically, the impact of fertilizers, invasive plant species, and garbage on the pond ecosystem of Nosehill will be conveyed in this blog.

            This is how the storm-water retention pond in Nosehill Park looks like:
  1. Light and the temperature of the water.
  2. The presence of nutrients such as nitrates (in mg/L), phosphates (in mg/L), sediments and dissolved solids such as sand and soil particles in the water.
  3. The dissolved oxygen content in the water (in ppm).
            The area of human activity that impacts all of the three factors is the use of fertilizers and other nutrients on surrounding rural areas in the pond ecosystem.


What are fertilizers?
            Fertilizers are materials that are used by humans to restore low-level nutrients in the soil to that of a higher concentration and to increase plant production from land. Estimates suggest that fertilizers containing nitrogen and phosphates double crop yields such as wheat and barley. However, at times the use of fertilizers can have devastating impacts to terrestrial and aquatic ecosystems and must therefore be used in a responsible manner. Negative impact of fertilizers on the terrestrial ecosystem is the build up of nitric acids in the soil it is used in. As soil bacteria convert the nitrogen content of fertilizers into nitrates, the presence of high levels of nitrates can result in the increase in concentration of nitric acids in the soil which can affect all organisms in the soil including the soil bacteria.
            The impact of fertilizers on aquatic ecosystems such as ponds can similarly be detrimental to the organisms that live in them.

How do nutrients enter aquatic ecosystems?
The three most common sources of nutrients in the pond ecosystem are:
  1. Runoff of water from surrounding areas.
  2. Sources of incoming water.
  3. Figure 2.  Nutrient cycling in the pond. 
    Texas Parks and Wildlife
    Development. (2007). Life in a Pond.
    Retrieved October 2, 2010 from
  4. Bottom Silt and dead vegetation in the pond.
How do fertilizers enter pond ecosystems?
The most common source of nutrients is runoff from farms and other outlying areas.
The USGA reports that up to 4% of fertilizer material applied to areas close to ponds may eventually runoff into the lakes and ponds through the drainage and sewage pipelines at times of heavy rainfall. When precipitation occurs, gases in the atmosphere mix with the water polluting it. When liquid water falls on land areas as precipitation, it forms runoff which may collect above the ground in areas called ‘surface water’ which includes lakes, rivers, ponds, oceans etc. It may also fall directly onto land surfaces and may filter into the ground through a process known as percolation over time. This involves the movement of water down the layers of the ground assisted by Earth’s gravitational force. Through water transport systems such as drainage and sewage pipelines, the precipitation that falls directly onto land surfaces is transported to nearby water bodies such as rivers, lakes, oceans and pond ecosystems. In the process, the precipitation also carries the nutrients, minerals and other sediments in the soil into the water bodies which may also include the nitrogen and phosphorus fertilizers that you have applied to your lawns. Also, leaves, grass clippings and other such materials too are carried into these water bodies through precipitation and heavy rainfall raising the nutrient levels in the pond. The transport of nutrients and other soil particles into the aquatic ecosystems resulting in a rapid increase in nutrient levels in the aquatic ecosystems is called nutrient loading. Nutrient loading causes the rate of plant growth in an aquatic ecosystem to increase which have devastating effects to life in the aquatic ecosystem.

What happens when fertilizers enter an aquatic environment?

Fig # 3: Algae Species 1 at Nosehill Pond
Taken by Pawan on October 10, 2010
Fig # 4: Spiked Water-Milfoil Myriophyllum
 spicatum at Nosehill Pond.
Taken by Pawan on October 10, 2010
            Fertilizers usually contain phosphorus and nitrogen compounds which are important for plant growth. When an aquatic environment gets loaded with too much of these nutrients, algae and other aquatic plants in the water grow at a rapid pace. The rapid increase in algae (called an algal bloom) and aquatic plant growth can affect factors such as light, temperature and dissolved oxygen content in the aquatic environment. Abundant aquatic plant growth on the water surface in a nitrogen and phosphorous-rich aquatic environment can decrease the amount of sunlight that penetrates the surface of the water. Since aquatic plants (such as algae) on the water surface utilize sunlight to carry out the process of photosynthesis (which is the reaction of carbon dioxide, water vapour and sunlight to produce oxygen and glucose), they reduce the amount of sunlight that enters the water thereby decreasing the temperature of the water. The decrease in sunlight that enters in the water and the temperature of the water can harm other aquatic organisms that live in the water since most aquatic organisms cannot survive below water temperatures of 5.0 °C. As algae and aquatic plants die, bacteria in the water use dissolved oxygen in the water to decompose them. Because decomposers flourish in an environment where a food source is abundant, the dissolved oxygen levels in the water drop quickly killing fish and other aquatic organisms that live in the environment. As more organisms die, the aquatic ecosystem slowly becomes unbalanced with the drastic decline in dissolved oxygen levels in the water used by the rapidly growing population of decomposers in the water.


            What are invasive plants?
Fig 5. Spiked Water-Milfoil Myriophyllum 

spicatum at Nosehill Pond
Taken by Pawan on October 10, 2010.
The invasive plant species shown in Figure 5 and 6 were found in the Nosehill pond ecosystem.

Fig 6. Common peppergrass Lepidium densiflorum
Taken by Pawan on October 10, 2010

            Invasive plants are plants which grow aggressively and quickly in ecosystems that are not naturally their own, displacing and often destroying other plants that grow in the area. When introduced, invasive plant species pose a great threat to terrestrial, coastal and freshwater ecosystems. They cause extinction of various species and loss of biodiversity in aquatic environments worldwide. They destroy and displace the native species which in turn decrease the biodiversity of the entire ecosystem. Since invasive plants often do not have predators in the ecosystem they have been introduced to, the population of the invasive plants grows in a very short period of time competing with native plants for food and resources. When two different species compete with one another over similar resources, this relationship is called interspecies competition. Compared to the invasive plants however, native plants have natural predators in the ecosystem that are dependent on the native plants for food and survival. Therefore, native plants are often unable to compete with the invasive plants and over time the population and biodiversity of the native plants dwindle.

How do invasive plants enter ecosystems?
Terrestrial invasive plant species can be introduced to new areas as ornamental plants in lawns and gardens. Once established, non-native terrestrial plants can spread by seed since the seeds are light enough to be carried by wind, fire, water, or animals. They can hitchhike on the shoes of hikers, tire treads of vehicles, boats and boat trailers, and in the furs and intestines of animals such as livestock, horses, and wildlife. Some invasive plants also have the ability to reproduce by sending out underground shoots which form new plants. Plants that reproduce by this method include the Camelthorn and the Bermuda grass species.
Aquatic invasive plant species can also be spread to native ecosystems through the transport of their seeds by wind, water and animals. An interesting example of the transportation of invasive aquatic plants by water could be through the dumping of fish tanks and aquariums that contain non-native aquatic vegetation into storm drains, lakes and ponds which is common when their owners can no longer care for them. An invasive aquatic plant species that is thought to have spread this way is the Giant Salvinia.

            Garbage or waste is unwanted or unusable materials that are disposed off on a regular basis. Waste types may be of different types such as municipal waste, construction waste, industrial waste, commercial waste, medical waste, hazardous waste, and biodegradable waste. Garbage or waste such as tissue, plastic, rope, paper, foil, cans, bottles etc, are at times improperly disposed off (thrown away) by humans inside natural environments and in turn affect terrestrial and aquatic ecosystems all around the world.

How does garbage enter ecosystems?
     Figure 7. Garbage littered around a beach.
Retrieved October 6, 2010

Human garbage can enter aquatic ecosystems through improper waste disposal which may then be carried by water (runoff at times of heavy rainfall) and by wind to form large deposits in aquatic ecosystems.
An example is the Great Pacific Garbage Patch, a nebulous floating junkyard stretching for miles in the Pacific Ocean. Sometimes called ‘a trash island’ the Garbage Patch is made up of plastic, the most commonly disposed type of garbage in the world. According to research some of the plastic is washed away from interior continental areas to the sea through sewers and other drainage systems and accumulates into the Great Pacific Garbage Patch with the help of  
Fig # 8 the Great Pacific Garbage
Patch (underwater)
Retrieved October 4, 2010
converging ocean currents at two main zones in the Pacific Ocean; the North Pacific Subtropical Gyre and the North Pacific Subtropical Convergence Zone. This area is known to be a ‘trash superhighway’ where plastic garbage is ferried between both zones from different continents at both sides of the Garbage Patch. At times, garbage (such as fishing nets and steel containers) may also be disposed directly onto the Pacific Garbage Patch from fishing boats and large cargo ships (which dispose hockey pads, computer monitors, resin pellets and LEGO octopuses yearly into the sea).

How does garbage affect ecosystems?
Garbage especially plastic are known to cause grave threat to the environment, harming ocean and marine life. Fish, birds, sea mammals and other water creatures are becoming poisoned and deformed because of plastic consumption. Plastic alone has resulted in deaths of a number of sea creatures.
Unlike other trash, plastic is not biodegradable, meaning that microbes that break down other substances do not recognize plastic as food. Even though sunlight and radiation does eventually ‘photodegrade’ or break down the bonds in plastic substances, the plastic never goes away from the ecosystem. Instead the plastic polymers are reduced to smaller and smaller substances which it makes it easier for marine life to eat and transfer to other organisms through the food chain, a process known as bioamplification.
Figure 9. Turtle entangled in a net.
Retrieved October 4, 2010
Figure 10. A chick albatross
whose stomach is filled
with debris.
Retrieved October 4, 2010
            A growing number of abandoned fishing nets in the sea are one of the largest dangers from marine debris. Nets entangle seals, turtles and other aquatic organisms, a phenomenon called ‘ghost fishing’ which drowns these organisms. Even more, plastic items can also be mistaken by marine animals as a source of food. Most often sea turtles are the most susceptible to being endangered by plastic. Often mistaking floating plastic bags as jellyfish, their common prey, sea turtles swallow plastic bags. They can also be caught into a variety of other objects such as plastic rings which constricts around their body often killing them in the process.
            Plastic resin pellets are another example of how plastic items affect marine animals. Since plastic resin pellets are a common industrial item, used at manufacturing sites and remoulded into commercial products, they often escape out of their confined facilities and accumulate in seas and other aquatic areas. They tend to float on the surface of water bodies and eventually photodegrade, but that takes a long time. In the meantime, the pellets pose a threat to coastal ecosystems and harm organisms such as the short-tailed albatross. Albatross parents rely on coastal ocean areas in the Pacific for food, mainly protein eggs of which they can use to feed their chicks. These protein eggs are similar in appearance to the plastic resin pellets. Unfortunately, albatrosses scoop up these pellets and other shiny items such as cigarette lighters from the ocean and feed them to their chicks. This causes rupture of organs and eventually death of these creatures.


Fertilizers, invasive species and garbage have adverse impact on aquatic ecosystems. They destroy the native species and cause imbalances in the ecosystem finally destroying the ecosystem itself. Human activities have resulted in high levels of pollutants entering these ecosystems causing extinction of various species besides causing environmental hazards. Our aquatic ecosystems need to be protected and pollution controlled through strict legislations curtailing such human activity.   

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