Back to: MICROBIOLOGY 400 LEVEL
Welcome to class!
Welcome back, amazing learner! It’s such a joy to continue this learning journey with you. Today’s topic is something you may have heard about in news reports or even witnessed in your environment, especially around rivers or lakes—Algal Blooms and Aquatic Ecosystem Disruption. Let’s break it down in a simple and relatable way that connects deeply with our Nigerian environment.
Algal Blooms And Aquatic Ecosystem Disruption
To start, algae are tiny plant-like organisms that naturally live in water. They are very important because they produce oxygen and serve as food for many aquatic animals. But when there is too much of them growing too fast, especially in one place, it causes what we call an algal bloom.
What Causes Algal Blooms?
Algal blooms happen when conditions in the water are just right—plenty of sunlight, warm temperatures, and most importantly, too many nutrients, especially nitrogen and phosphorus. These nutrients mostly come from:
Fertilisers used on farms and washed into rivers during rainfall
Sewage and untreated wastewater dumped into water bodies
Industrial waste from factories
Animal waste from livestock farms
These nutrients act like “super food” for the algae, causing them to multiply rapidly.
Why Are Algal Blooms a Problem?
Oxygen Depletion (Eutrophication)
When algae grow too fast and die, they sink to the bottom and are decomposed by bacteria. This process uses up oxygen in the water, leading to oxygen depletion. Fish and other aquatic animals then suffocate and die.
Example: Fishermen in the Ogun River area sometimes notice mass fish deaths after heavy rain—this could be due to an algal bloom.
Toxin Production
Some algae, especially blue-green algae (cyanobacteria), produce harmful toxins. These can poison fish, animals, and even humans who drink or swim in the water.
Blocked Sunlight
Thick algae on the water surface prevent sunlight from reaching underwater plants. This disrupts photosynthesis and affects the entire aquatic food chain.
Bad Odour and Water Taste
Algal blooms can make water smell bad and taste unpleasant, making it difficult to use for drinking, washing, or fishing.
Biodiversity Loss
When certain algae dominate a water body, they outcompete other species, reducing biodiversity and harming the natural balance of aquatic life.
Nigerian Context
In places like Lagos Lagoon or River Benue, large algal blooms have been reported during dry seasons, especially near areas with farming or waste dumping. Communities depending on those water bodies for fishing or drinking water often suffer.
How Can We Prevent or Control Algal Blooms?
Reduce the use of chemical fertilisers and promote organic farming
Treat wastewater before releasing it into rivers or lakes
Educate communities on proper waste disposal
Encourage buffer zones with grasses near rivers to trap nutrients
Monitor and manage pollution sources
Summary
- Algal blooms occur when algae grow excessively due to excess nutrients like nitrogen and phosphorus.
- They cause oxygen depletion, produce toxins, and damage aquatic life.
- Controlling waste and managing nutrient runoff helps prevent blooms and protect water ecosystems.
Evaluation
- What are algal blooms, and what causes them?
- List two ways algal blooms affect aquatic ecosystems.
- Mention two methods for preventing algal blooms in Nigerian rivers.
You’ve just tackled a major environmental issue with confidence and clarity. Remember, your growing knowledge is powerful—it can help solve problems in your community and beyond. Keep up the great energy and get ready for the next exciting topic with Afrilearn!