Implement this Lesson:
This unit can be used in conjunction with a carbon cycle lesson, microscope unit, or ocean unit.
Learning Objective:
- Observe changes in algal growth in response to nutrient levels.
- Explain changes in water quality due to algal growth.
- Assess the potential affects of water quality on a water ecosystem.
Texas Essential Knowledge and Skills (TEKS)
6.11(A) research and describe why resource management is important in reducing global energy poverty, malnutrition, and air and water pollution
6.11(B) explain how conservation, increased efficiency, and technology can help manage air, water, soil, and energy resources
6.12(A)* investigate how organisms and populations in an ecosystem depend on and may compete for biotic factors such as food and abiotic factors such as availability of light and water, range of temperatures, or soil composition
6.12(B) describe and give examples of predatory, competitive, and symbiotic relationships between organisms, including mutualism, parasitism, and commensalism
6.12(C) describe the hierarchical organization of organism, population, and community within an ecosystem
6.13(A) describe the historical development of cell theory and explain how organisms are composed of one or more cells, which come from pre‐existing cells and are the basic unit of structure and function
6.13(B) identify and compare the basic characteristics of organisms, including prokaryotic and eukaryotic, unicellular and multicellular, and autotrophic and heterotrophic 6.13(C) describe how variations within a population can be an advantage or disadvantage to the survival of a population as environments change
7.10(A)* describe the evidence that supports that Earth has changed over time, including fossil evidence, plate tectonics, and superposition 7.10(B)* describe how plate tectonics causes ocean basin formation, earthquakes, mountain building, and volcanic eruptions, including super volcanoes and hot spots
7.11(A)* analyze the beneficial and harmful influences of human activity on groundwater and surface water in a watershed
7.11(B)* describe human dependence and influence on ocean systems and explain how human activities impact these systems
7.12(A)* diagram the flow of energy within trophic levels and describe how the available energy decreases in successive trophic levels in energy pyramids
7.13(A)* identify and model the main functions of the systems of the human organism, including the circulatory, respiratory, skeletal, muscular, digestive, urinary, reproductive, integumentary, nervous, immune, and endocrine systems
7.13(C)* compare the results of asexual and sexual reproduction of plants and animals in relation to the diversity of offspring and the changes in the population over time
7.13(D)*describe and give examples of how natural and artificial selection change the occurrence of traits in a population over generations
7.14(A) describe the taxonomic system that categorizes organisms based on similarities and differences shared among groups
8.10(A) describe how energy from the Sun, hydrosphere, and atmosphere interact and influence weather
8.10(B) identify global patterns of atmospheric movement and how they influence local weather
8.10(C) describe the interactions between ocean currents and air masses that produce tropical cyclones, including typhoons and hurricanes
8.12(B) describe how primary and secondary ecological succession affect populations and species diversity after ecosystems are disrupted by natural events or human activity
8.12(C) describe how biodiversity contributes to the stability and sustainability of an ecosystem and the health of the organisms within the ecosystem
8.13(A) identify the function of the cell membrane, cell wall, nucleus, ribosomes, cytoplasm, mitochondria, chloroplasts, and vacuoles in plant or animal cells 8.13(C) describe how variations of traits within a population lead to structural, behavioral, and physiological adaptations that influence the likelihood of survival and reproductive success of a species over generations
8.13(B) describe the function of genes within chromosomes in determining inherited traits of offspring
Red Tides — When the Ocean Turns Red
Sometimes the ocean water along the coast turns reddish-brown, orange, or even green.
That’s called a red tide — but it’s not really made of blood or paint!
A red tide happens when tiny algae in the water grow too fast and too many. This sudden growth is called a “bloom.”
What Causes Red Tides?
The ocean is full of microscopic algae, also known as phytoplankton — tiny plant-like organisms that float near the surface.
Most of the time, these plankton are good because they:
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Make oxygen
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Feed fish and other sea animals
But sometimes, certain kinds of algae multiply too quickly, especially when:
Warm water- Algae grow faster in warm, sunny weather
Nutrients in the water- Runoff from farms, cities, or rivers add fertilizer-like nutrients
Calm seas- Still water helps the algae stay near the surface
When this happens, the water becomes cloudy and discolored — that’s a red tide!
What Makes the Tide “Red”?
Not all red tides are the same color.
The color depends on the type of algae causing the bloom.
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Some are red or brown (like Karenia brevis, common in the Gulf of Mexico).
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Others can look green or yellow depending on the species.
Even though it looks pretty, it can be dangerous to animals and people.
Why Red Tides Can Be Harmful
Some red tides produce toxins, or poisons, that can harm marine life.
Fish- The toxins can damage their gills, making it hard to breathe.
Dolphins and manatees- can get sick from eating fish that have the toxins
Shellfish (like oysters and clams)- Store toxins in their bodies, making them unsafe to eat
Seabirds- Can get poisoned from eating fish during a red tide
People can also feel sick if they eat shellfish caught during a red tide or if they breathe in ocean air near a bloom — it can irritate the eyes, throat, and lungs.
Red Tides on the Texas Coast
Red tides sometimes happen along the Texas Gulf Coast, especially in late summer and fall when the water is warm.
Scientists from the Texas Parks and Wildlife Department and other groups monitor red tides by testing the water.
If a bloom is detected, they post warnings to keep people safe from swimming or fishing in affected areas.
Can Red Tides Be Stopped?
It’s hard to stop a red tide once it starts, but we can help prevent them!
Reduce pollution- Less fertilizer and waste means fewer nutrients for algae to grow
Keep waterways clean- Picking up trash keeps harmful materials out of the ocean
Learn and share- Understanding red tides helps communities stay safe.
Scientists are also studying how winds, currents, and weather affect red tides to better predict when they might happen.
Fun Facts!
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“Red tide” is also called a harmful algal bloom (HAB).
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The algae that cause red tides are as small as dust, but together they can color miles of water!
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Dolphins and sea turtles sometimes move away from red tide areas to find clean water.
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The Gulf of Mexico is one of the most studied places for red tides in the world.
Why It’s Important to Know About Red Tides
Even though red tides can be harmful, learning about them helps us protect our oceans, animals, and ourselves — keeping the Gulf of Mexico healthy and full of life!
Possible Books:
- What is Red Tide
- The Mystery of Red Tide
- Red Tide Alert
Materials Needed:
- Poker chips-at least two different colors (Colored paper or other types of identifiers can also be used if poker chips aren’t available.)
- Playing area (open area outside or inside suitable for a walking or running tag game)
- Boundary markers (cones, chalk line, rope, etc.)
- Gym vests or other identifiers for “fish”
- Chart to record data (easel with paper, dry erase board, chalkboard, clipboard, etc.)
- Pen, pencil, marker, etc.
Lesson Plan:
- Discuss the effects of harmful algal blooms on fish populations and how toxins released into the water may change fish numbers.
- Explain that in this activity, students will be fish and algae interacting in the ocean (playing field). Remind students of physical safety issues, and let students know if this activity will involve running or only walking.
- Explain the rules of the activity as follows: Algae are trying to get to the finish line without being eaten (tagged) by the fish. Tagged algae must show their poker chips to the fish that tagged them. If the chip is red, the alga released toxin into the water that killed the fish, so the fish and alga go to the finish line to become algae in round two. If the poker chip is not red, the alga was eaten by the fish. In round two the alga becomes a fish.
- Randomly divide the class into fish and algae. For the first round, in a class of twenty-five students designate about four students as fish.
- Have students designated as algae, stand along the end of the playing area identified as the starting line.
- Have students designated as fish; enter the playing field at least halfway between the start and finish lines. Have fish turn their backs to the algae.
- Have algae close their eyes and give each alga a poker chip. Algae should put the chip into a pocket without looking at it or keep it in a hand. After the chips are distributed, the algae may open their eyes.
- Once chips are distributed the algae and fish may face each other.
- On the start signal, algae try to get to the opposite end of the playing field.
- After each round the number of fish and algae are recorded, and chips are redistributed. (If all fish or algae die, record the results, discuss it, and start again with a new population.)
- Following the activity with a discussion of the change in population size for both organisms and relate this to what happens in nature. Additional discussions could focus on carrying capacity and how it is affected by environmental factors.