Imagine a large inland sea located in a semi-desert region that supports a booming fishing and shipping trade. Through various lines of research, the following facts about this sea have been uncovered:
Thirty years ago, upstream irrigation systems were introduced to supply surrounding farms.
About twenty years ago, the water level of the sea began to drop noticeably. Today, over half the water volume has been lost.
Salt content of this inland sea has nearly doubled. Strong winds are blowing the salt, which accumulates along the shore, into nearby agricultural lands.
Pesticides and other chemicals used in agriculture and adjacent industries have seeped back into the sea.
The lack of proper sewage facilities has resulted in the dumping of waste into the sea.
What effects would you expect these factors to have on this ecosystem? Explain your answer. What would you propose as solutions to this potential ecological catastrophe?
To understand the complexities of the issue at hand, we must first look at what cause inland seas. According to the geographic descriptions, it was more than likely a result of tectonic plates shifting during the development of our current landmass positions. When they shift, the land can either sink or have its ocean basins fill with water from flooding. This is called Transgression. Either case causes a development of a salty body of water with aquatic animals trapped inside. Being that is surrounded by a desert-like biome, it is more likely to be the result of the tectonic plates spreading, causing the land to sink and fill in with salt water. As this occurs, prey animals will thrive through a lack of predators, such as smaller fish. This enables the fishing industry to boom as it did.
The fishing trade in this area is at risk of failing. When humans alter systems such as this one, their stability declines. For a while this was more than likely a self-sustaining environment. The implementation of irrigation systems have first, affected the wildlife surrounding the inland sea, which was assisting its survival. Every animal plays a role in the ecosystem. When the industries were built around the body of water, the land ecosystem suffered. As a result, the fish in the corresponding water will eventually suffer. Being a self-sustaining system, it will keep water cycling by itself. When the system was built for local farmers, water supplies were being pulled from the natural made sea and into other locations. This is normally fine for areas, but in one such as this, without any natural made filtering system, it will begin losing water. The process will take a while due to the water cycle consistently adding some back, but will occur. As the water levels decrease, so will the fish. This is the cause of research number two.
With an increasing salinity count, the pH of the water and soil will change as well. Adding salt to the soil as it is doing through wind patterns, slowly crops, which once thrived in the surrounding land, will begin to deplete. Not all plants require the same nutrient levels. If the farmers' crops are thriving now, with lower salinity counts and lower pH's then the same crops will not grow as well in higher salt concentrations and higher pH values. Another factor affecting local farmers as well as the fishermen is the pesticides and chemicals. These will not only affect the water's pH, it will also affect the stability of the water for the fish to live in. As more chemicals and sewage are added to a body of water, the fish have no choice but to take in those hazardous wastes. At first, humans will grow sick of ill-prepared fish. Second, the fish will slowly begin to die off causing the fishermen to lose a source of income.
The future of this environment is devastating. Local animals, which do use the sea as a source of food, will inadvertently be affected as well. While these animals may be capable of migrating, they cannot move far into a desert without and inevitable death. They know that. Therefore, they will stay, but will not survive if nothing is done to change the area's filtering technology. This is a classical food-web analysis. Even changing one abiotic factor such as water amount, affects the entire system's functioning.
In order to fix the environment, a proper irrigation system needs to be installed, complete with water purification and proper waste disposal. This would entail the development of a way to pump salt water into the inland sea to keep the water levels appropriate for the culturing of fish. It also would enable the water levels to be maintained. When a proper water filtration system is installed, water can be pulled from deep within the earth or from the local ocean. It would also be ideal to build some form of water tanks around the areas to trap falling rainwater. This water can also be purified and cleaned to use at the local farms, which will aid the salt water to replenish itself. In replenishing itself, the salt concentrations will decline from the evaporated sea and begin to add back to the water itself. Doing this will ensure a form of balance in the water which will allow the fish to begin surviving again due to the decrease in chemicals, pollutants, and wastes being disposed of.
After years of carefully monitoring chemical, pH, and nutrient levels of the inland sea the system has a small chance of stabilizing back to its prior arrangement.
The excessive use of fertilizers in agriculture practices can cause ecological impacts such as eutrophication. The nitrogen in the fertilizers will stimulate algal growth in large bodies of water. The increase in algae will increase the biological oxygen demand (BOD) and thereby decrease the dissolved oxygen (DO). This can choke out sensitive organisms. The accumulating dead matter, increased photosynthetic productivity from the algae will create conditions perfect for turning that large body of water into a meadow.