lecture recording on 14 March 2025 at 09.48.56 AM

Organic Matter in Ecosystems

• Organic matter can originate from various sources, including non-man-made resources like sewage effluent.

• Each ecosystem maintains a baseline level of organic matter, typically from leaves and animal waste, which it can process effectively.

• Issues arise when excess organic matter is introduced, overwhelming the system's natural capacity for nutrient processing.

Sewage Effluent and Eutrophication

• Sewage effluent is nutrient-rich and can disrupt aquatic ecosystems when excess organic matter is released.

• Eutrophication: A process driven by nutrient overload in which plants cannot absorb all incoming nutrients, leading to overgrowth of algae.

• Algae rapidly proliferates, forming thick mats that block sunlight from reaching underwater plants.

• When submerged plants die due to lack of light, decomposition occurs, consuming oxygen in the water.

Consequences of Eutrophication

• Depleted oxygen results in hypoxic conditions, threatening aquatic life, particularly fish.

• Large fish kills have been observed as a consequence, as seen in various regions, including the Murray-Darling Basin and Newcastle Harbor following floods.

• The resulting dead zones in water bodies can span kilometers, affecting both local ecosystems and human communities.

Impact on Local Ecosystems

• In coastal areas, floodwater runoff containing sewage and nutrients contributes to significant die-off events in lakes and rivers.

• Farming activities, even many kilometers away, can have dire impacts on delicate ecosystems like the Great Barrier Reef due to runoff of fertilizers and other pollutants.

• It is a challenge to communicate the environmental impacts of farming to producers, especially when they are far removed from affected ecosystems.

Laboratory Procedures

• During lab experiments, ensure to follow the instructions concerning heating and measuring pH levels accurately.

• Calibration of equipment may not be necessary if systems are already set up correctly to prevent inaccuracies.

• Accurate measuring of sediment and organic content is critical for valid experimental outcomes.