Ecology

Tropical Rainforest

The tropical rainforest is a forest that is consistently warm and has a high rainfall of more than 2000mm annually. It has a unique dense vegetation with different plant layers and unique characteristics. These include the emergent layer, characterised by very tall trees, the canopy layer, characterised by the primary layers of rainforest that form a dense roof of leaves and branches, the understory layer located below the canopies and receiving limited sunlight, and finally, the bottom layer of the rainforest called the forest floor.

Figure 3.16: Rainforest canopy layers The tropical rainforest is home to a huge variety of plants and animals because the weather is consistently warm and rainy, and there is plenty of food and resources available. This creates a stable and comfortable environment that allows many different species to thrive and coexist.

Figure 3.17: Tropical rainforest This habitat is home to tiny microorganisms such as bacteria and fungi that help break down dead plants and animals in the soil. Some bacteria help plants grow by fixing nitrogen. when they grow in the roots of the plants. Nitrogen fixation is a biological process where nitrogen in the atmosphere is converted into ammonia (another form of nitrogen) by certain bacterial species like Rhizobium, Azotobacter, etc. Protoctista like Amoebae and Flagellates can also be found in the forest soil.

The rainforest is home to tall trees like ceiba or kapok, African mahogany, wawa, Odum and rubber. Other plants found include epiphytes such as orchids, ferns and bromeliads that grow on other plants, and vines that climb up the trees.

The rainforest is also home to a vast array of animals like monkeys, forest elephants and birds like parrots, sparrows and eagles. Reptiles such as snakes and lizards are also present along with amphibians like frogs and salamanders, Insects like butterflies and ants and arachnids such as spiders and scorpions.

National Geographic documentary on rainforests:

https://www.youtube.com/watch?v=3vijLre760w Characteristics of tropical rainforests

1. Has heavy rain, over 2000mm every year.

2. Temperatures that stay between 20-30°C.

3. The air is always humid.

4. The rainforest is home to a huge variety of plants and animals.

5. The plants grow in layers with different levels of trees, shrubs, and vines.

Adaptations of plants in the tropical rainforest

1. Plants such as African mahogany have huge leaves with pointed tips that allow water to slide off, preventing fungi from growing on them.

2. Epiphytes such as orchids and bromeliads grow on other plants to reach the sunlight filtering through the dense canopy.

3. Vines and lianas such as pothos (candle vine) climb up trees to reach the sunlight in the upper canopy.

4. Trees such as kapok develop big, flat roots (buttress roots) that help them stand tall in thin soil and absorb nutrients

Figure 3.18: A large tropical rainforest tree with supporting buttress roots.

Adaptations of animals in the tropical rainforest

1. Animals like chameleons have colours and patterns (camouflage) that help them to blend with the environment and hide from predators.

2. Bush babies and other animals live in trees to avoid predators that roam the forest floor.

3. Monkeys and pangolins have prehensile tails that act like an extra hand, helping them grip tree branches and move through the forest canopy.

4. Pangolins and other animals are nocturnal, meaning they are active at night, to avoid predators that hunt during the day.

Activity 3.10 Exploring Tropical Rainforests

Materials needed

• Whiteboard

• Markers

• Diagrams of tropical rainforest layers (emergent, canopy, understory, forest floor) Procedure

1. In groups, share what you know about tropical rainforests.

2. Discuss each layer’s unique features and how plants and animals adapt to that layer, using the printed copies of the tropical rainforest layers and zones as a guide.

3. Choose a plant or animal as a group and create a poster or drawing that illustrates its adaptations.

4. Share your drawing or poster with other groups.

Savannah and Desert Habitats

The savannah is a mixed grassland characterised by a variety of grasses, scattered trees and seasonal wet and dry cycles supporting a rich range of plant and animal species. In contrast, deserts are dry regions defined by extremely low rainfall, extreme temperature fluctuations and bare vegetation where life has adapted to survive in challenging conditions. The savannahs near the equator are called tropical savannahs.

Figure 3.19: Tropical Savannah

Types of Tropical Savannahs

In Africa, there are three main types of tropical savannahs:

Table 3.1: Types of Savannahs in Africa and their grass vegetation.

Types of savannahs in Africa Grass vegetation Guinea Guinea grass, Bermuda grass, Gamba grass, and elephant grass.

Sudan Tussock grasses and thatching grasses Sahel Drin grass, tussock grass and Bushman grass

Figure 3.20: Types of grasses Organisms in the Savannah

1. Microorganisms: These are usually bacteria and the fruiting body of fungi, such as mushrooms (for example, the termitomyces).

Figure 3.21: Fruiting body of Termitomyces

2. Trees: These comprise acacia trees, shea trees, palm trees and baobabs.

Figure 3.22: The baobab tree

Figure 3.23: Acacia tree

3. Animals: The savannah is home to many animals, e.g. giraffes, elephants, antelopes, snakes, termites, ostriches and lions roaming freely among the grasses and trees.

Figure 3.24: Ostriches

NOTE: Click on the link below to watch a short documentary on Savannah Bing Videos Desert Deserts are dry areas where rainfall is extremely low. They can be very hot during the day and freezing at night, and because of these tough conditions, you will not find many plants or animals there.

Figure 3.25: Desert

Organisms in the Desert

1. Bacteria: They are mostly algae and thermophiles (bacteria that love hot temperatures).

2. Fungi: These desert fungi help recycle nutrients in the soil.

3. Plants: The saguaro and prickly pear cacti are tough and can store water.

Figure 3.26: Saguaro and cacti You will also find shrubs like sagebrush and creosote bush. They have adapted to survive in the heat.

Figure 3.27: Sage bush

4. Animals like camels, kangaroos, fennec foxes, rattlesnakes, burrowing owls, roadrunner Birds, Ants and scarab beetles are found.

Figure 3.28: Camel Figure 3.29: Fennec Fox

Figure 3.30: Dessert Lark

NOTE: Click on the link below to watch a short documentary on Deserts Bing Videos Characteristics of Savannahs and Desert Habitats The Savannah

1. Seasonal rainfall: Savannahs experience distinct wet and dry seasons.

2. Vegetation: The flora mainly consists of grasses with scattered drought- resistant trees.

3. Animal life: Fauna includes animals adapted to grazing, browsing and seasonal migration.

4. Soil quality: Soils are often nutrient-poor but well-drained.

The Desert

1. Low rainfall: Deserts receive extremely low rainfall, often less than ten inches per year, with high evaporation.

2. Vegetation: Flora is scarce, primarily made up of succulent and drought- resistant shrubs.

3. Animal adaptations: Fauna is adapted to survive extreme temperatures and water scarcity.

4. Soil composition: Desert soils are mainly sandy with minimal organic content or consist of rocky terrain.

Adaptations of organisms in the Savannah

1. Camouflage: Some animals, such as lions and zebras, use camouflage for hunting and protection.

2. Migration: Large mammals like wildebeests migrate to find water and fresh grazing.

3. Water conservation: Some savannah animals, such as giraffes, can go long periods without water.

4. Deep roots: Savannah plants, like acacia trees, develop deep roots (tap roots) to access groundwater.

5. Fire resistance: Many grasses and trees can withstand periodic fires, such as elephant grass.

Adaptations of organisms in the Desert

1. Nocturnal behaviour: Many desert animals, including kangaroo rats and foxes, are nocturnal to avoid daytime heat.

2. Burrowing: Some animals, like ground squirrels and meerkats, burrow into the soil to escape heat and predators.

3. Fat storage: Certain animals, such as gerbils and camels.

4. Water storage: Many desert plants, like cacti and aloe vera, store significant amounts of water in their tissues.

5. Reduced leaves: Some desert plants, such as the Joshua tree, have reduced leaves to minimise water loss.

6. Extensive roots: Plants like Welwitschia have deep and extensive root systems to increase water absorption. Welwitschia is found only in the Namib desert of south-western Africa, near the coast of Angola and Namibia

Figure 3.31: Welwitschia

Activity 3.12 Selection of favourites in the habitat

1. Draw your favourite desert animal or plant and outline its unique adaptations that help it survive in such a harsh environment.

2. Why do you think deserts have fewer plants and animals compared to other habitats like forests or savannahs? Discuss your answer in groups.

Activity 3.13 Debate on the feasibility and implications of converting desert areas into forested regions Materials needed

• Paper

• Pens

• Research materials (Textbooks, articles, or internet access if available) Instructions

1. With your debate team, research and discuss your stance, such as:

a. Proponents (for reclaiming deserts into forests): Potential benefits (e.g., increased biodiversity, carbon sequestration, improved climate), methods for reclamation (e.g., irrigation, soil improvement), and successful case studies.

b. Opponents (NOT possible to reclaim deserts into forests): Challenges (e.g., water scarcity, cost, ecological impact), potential negative consequences (e.g., displacing native species), and the practicality of large-scale projects.

2. Present your arguments and, alternatively, respond to each other’s arguments.

3. The class discusses the arguments presented.

Lagoon Habitats

A lagoon is a shallow body of water that is separated from larger bodies of water, like seas and oceans. This separation is often caused by barriers such as sandbars, barrier islands or coral reefs. Lagoons are formed through several natural processes:

1. Sediment deposition occurs when soil and sand are carried by water and settle in one place.

2. Wave action: Waves shape the shoreline and help create barriers.

3. Growth of coral reefs or barrier islands: These structures can form over time, creating a lagoon behind them.

4. Lagoons often contain a mix of freshwater and saltwater from the sea, called brackish water. The salinity (saltiness) can change. During low tide, freshwater mixes easily with lagoon water, lowering the salinity. At high tide, more ocean water flows in, increasing the salinity.

Biodiversity in Lagoons

Lagoons are rich in biodiversity, meaning they are habitats for many different species, including fish, birds, insects and plants. They also serve as important breeding grounds for many species.

Types of Lagoons

There are two main types of lagoons:

1. Coastal lagoons: Found along coastlines, separated from the sea.

2. Atoll lagoons: Located within coral atolls, surrounded by coral reefs.

Lagoons in Ghana

In Ghana, you can find several lagoons, including Benya Lagoon in Elmina.

Figure 3.32: Benya Lagoon in Elmina in the Central region of Ghana

Figure 3.33: Korle Lagoon in Accra

Figure 3.34: Keta Lagoon in the Volta region of Ghana Threats to Lagoons Unfortunately, lagoons face many threats, such as:

1. Pollution: Harmful substances that can damage ecosystems, such as seen in the Korle Lagoon below.

Figure 3.35: A polluted lagoon

2. Eutrophication: When excessive nutrients lead to algae overgrowth. During the day, algae photosynthesise in the light and produce vast quantities of oxygen, more than enough to oxygenate any body of water, even where there is much decay and decomposition. At night, every organism in an ecosystem (in this case, the lagoon), including the algae, respires. Aerobic respiration results in the removal of oxygen from the surroundings by many organisms, respiring at night, when there is no photosynthesis to supply them with oxygen, leading to the death of the organisms.

3. Habitat destruction: Human activities that destroy these important environments.

To wrap up on the threats to lagoons, lagoons are vital ecosystems that support a wide range of life. By learning about them, we can appreciate their importance and find ways to help protect them. Happy exploring.

Self-Reflection What do you think we can do to help protect lagoons and their ecosystems?

Characteristics of Lagoons

1. Fluctuating salinity and temperature: Lagoons experience changes in saltiness( creating brackish water) and temperature due to tides and freshwater inflows.

2. Shallow depth: Most lagoons are relatively shallow, typically just a few metres deep.

3. High biodiversity: Lagoons support a wide variety of life, including fish, birds, and plants.

4. Slow water flow: The water in lagoons flows slowly and sluggishly, creating a unique habitat.

Adaptations of organisms in lagoon habitats Now, let’s explore how different organisms have adapted to thrive in lagoons.

1. Osmoregulation: Some organisms, like crabs and oysters, have special features to tolerate changing salt levels.

2. Respiratory features: Organisms may have efficient ways to breathe in low-oxygen conditions. For example, some move to the surface to breathe.

3. Burrowing behaviour: Oysters and other organisms burrow into sediments to cope with extreme temperatures.

4. Feeding strategies: Many lagoon organisms, like snails, are detritivores or filter feeders, feeding on organic matter that collects in sediments.

5. Reproductive strategies: Some species produce many eggs that hatch into larvae, which can disperse widely.

6. Camouflage and toxins: To avoid predators, some organisms use camouflage or produce toxins.

7. Mobility: Many lagoon animals are highly mobile and can quickly move to better conditions.

8. Mangroves: Some of these coastal plants have special roots called pneumatophores that help them exchange gases with the atmosphere.

Lagoons are incredible ecosystems rich in life and diversity. By understanding their characteristics and the adaptations of the organisms that inhabit them, we can appreciate the delicate balance of these environments.

Activity 3.14 Surviving in the Lagoon - exploring adaptations through fieldtrips

1. Visit a lagoon and take note of all the organisms found in and around it.

2. How are they able to survive respectively?

3. Look out for special features or structures, if any.

4. Write down all observations and findings for discussion.

Activity 3.15 Exploring mangroves

1. Look up pictures of mangrove trees from textbooks, journals or the internet.

Figure 3.36: A mangrove tree

2. How do you think their unique roots help them survive in lagoon environments?

Estuaries In estuaries, freshwater meets the sea. Let’s discover what makes these ecosystems so special and how the organisms living there adapt to their unique environment.

Estuaries are coastal water bodies where freshwater from rivers and streams converges or meets with saltwater from the ocean. These ecosystems are dynamic, influenced by tides that bring in seawater and freshwater inflows that dilute it.

Acting as transitional zones between land and sea, estuaries feature varying salinity levels (brackish) and nutrient concentrations, shaped by tidal movements, river flow, and wind patterns.

These habitats are crucial for many species, offering nurseries for juvenile fish and feeding grounds for migratory birds. However, estuaries face significant threats from pollution, including runoff from agriculture, industrial waste, and urban development. Examples of estuaries include the Volta River Estuary near Ada and the Rivers Pra and Densu estuaries located in Ghana.

Characteristics of Estuaries

1. Deeper than lagoons: Estuaries tend to be deeper than lagoons, creating different habitats for organisms.

2. Consistent freshwater inflow: Estuaries always receive freshwater from rivers and streams.

3. Fast and strong water flow: The flow of water into an estuary can be quick and powerful, especially during heavy rains or floods.

4. Fluctuating salinity: Salinity levels in estuaries can change rapidly, influenced by tides and freshwater input.

Activity 3.16 Exploring Estuaries - a delicate balance Materials needed: Pictures of different estuaries (as shown below).

Figure 3.37: Ankobra estuary in Ghana Figure 3.38: Ada estuary in Ghana

Figure 3.39: Pamlico Sound estuary in the USA Procedure:

1. Observe pictures of different estuaries and discuss the types of plants and animals likely to be found there.

2. How well are these organisms going to survive?

3. Write down all findings and discuss with other classmates.

Adaptations of Organisms in Estuaries

1. Salt regulation in fish: Many fish, like salmon and eels, can regulate their internal salt concentrations, allowing them to thrive in both freshwater and saltwater.

For example, salmon hatch in freshwater, migrate to the ocean, and return to rivers to spawn.

2. Burrowing for safety: Species like mussels and clams burrow in sediment to avoid predators and harsh conditions.

3. Streamlined bodies: Some organisms have flattened or streamlined bodies to navigate strong currents and hide in sediments.

4. Anadromous fish migration: Anadromous fish, such as pink salmon, use estuaries as a pathway from the ocean to freshwater for spawning.

5. Filter feeders: Oysters and barnacles have specialised feeding structures to filter plankton and detritus from the water.

6. Mangrove roots: The roots of mangrove plants provide habitat and protection for young fish and other aquatic organisms.

7. Salt-tolerant seagrasses: Seagrasses can tolerate high salt concentrations, providing food and shelter for marine life.

Activity 3.17 Creating an Interactive Map

1. Draw a migration route of a pink salmon from the ocean to a river.

2. Research different types of seagrasses and other organisms that may be found along the migration route, and include these organisms on your map

3. Mount your work in class to compare and discuss with your friends.

Exploring Seashore Habitats

Learners, today, we are diving into the fascinating world of seashore habitats, where land meets the ocean. This vibrant ecosystem is rich in nutrients and filled with diverse life forms. Let’s explore the different zones of the seashore and discover the amazing organisms that inhabit them.

The Zones of the Seashore

The seashore is made up of zones. These are:

1. Supralittoral Zone (Splash Zone)

Description: This is the uppermost zone; it’s often exposed to salt spray and strong waves.

Organisms: Lichens, algae, barnacles, and periwinkles thrive here.

Adaptations: Organisms in this zone must withstand drying out (desiccation) and fluctuating temperature changes because of sea water splashing.

2. Littoral Zone (Intertidal Zone)

Description: This area lies between the high and low tide marks, experiencing regular submersion and exposure due to tidal movements.

Organisms: Seaweeds (algae), mussels, barnacles, crabs, starfish, and sea anemones call this zone home.

Adaptations: These organisms deal with frequent changes in temperature, salinity, and moisture.

3. Sublittoral Zone (Subtidal Zone)

Description: This zone extends from the low tide mark to the edge of the continental shelf and is always submerged.

Organisms: Sea grasses, kelp, various fish species, sea urchins, and coral reefs thrive here.

Adaptations: Organisms in this zone adapt to stable aquatic conditions while needing to tolerate varying light levels.

Figure 3.40: A rocky seashore Figure 3.41: A sandy beach at Krokobite in Ghana

Activity 3.18 Our seashore world

1. Draw and describe how a barnacle would anchor itself to survive in the intertidal zone. What adaptations does it need to survive?

2. Imagine you’re a crab. Create a short story about a day in your life in the intertidal zone. How do you find food and avoid predators?

3. Research one organism from the sublittoral zone. Create a poster that includes its habitat, adaptations, and any interesting facts.

4. Share your drawing, story and posters with the class.

Adaptations of Organisms in the Seashore Habitat

Let’s dive into the fascinating adaptations that help organisms survive in the challenging seashore environment and discover how these amazing animals and plants, and algae thrive in their unique habitat.

Adaptations of seashore animals

1. Protective Shells and Exoskeletons: Many seashore animals, like snails and crabs, have shells or exoskeletons that protect them from predators and desiccation (drying out).

2. Anchoring Mechanisms: Some animals, such as mussels and starfish, use byssal threads and tube feet, respectively, to cling tightly to rocks, preventing them from being swept away by waves.

3. Flattened Bodies: Animals like limpets and chitons have flattened bodies to reduce resistance against strong waves.

Figure 3.42: Limpets on a rocky seashore

4. Burrowing Behaviour: Clams and worms burrow into the mud to escape predators and prevent drying out.

5. Movement Strategies: Some seashore animals move to tidal pools or migrate to deeper waters during low tides to find shelter and food.

Activity 3.19 Deep dive at the seashore

1. Draw an imaginative shell that would best protect a seashore animal. List the features it has for keeping the animal safe.

2. Think like a mussel. Write a short diary entry about your day clinging to a rock during a storm. What challenges do you face?

3. Imagine you’re a crab, create a map of your journey from the shoreline to a tidal pool during low tide. What obstacles would you encounter?

4. Share these results with your friends in class.

Adaptations of seashore plants

1. Physical Adaptations: Seashore vascular plants develop deep roots, thick cuticles, and waxy coatings to withstand high tides, waves, and to conserve water.

Figure 3.43: A plant at the seashore

2. Physiological Adaptations: Some plants have developed salt tolerance and drought resistance to survive during periods of high salinity and water scarcity.

Activity 3.20 Plants on the shore discussions

1. Imagine a “super plant” that can survive in harsh seashore conditions.

What special features would it have? Draw it and share with the class.

2. Why do you think being able to tolerate salt and drought is important for plants in the seashore habitat? Share your thoughts in small groups.

River A river is a natural flowing freshwater body which is connected to other water bodies such as oceans, lakes, other rivers and wetlands. It typically has a narrow and winding course with constant movement, and may take its source from springs, lakes, rocks and glaciers. Depth varies along its length and may have rapids, waterfalls, dams or tributaries. Rivers support aquatic life forms such as algae, plants (e.g. water lily, water lettuce and water hyacinth), fish (e.g. salmon, Tilapia and catfish), and insects (e.g. water beetles, dragonflies, mayflies and stoneflies), amphibians (e.g. frogs, toads and newts) and other invertebrates such as snails.

Adaptations of organisms in rivers and streams

1. Plants that are adapted to life in rivers often have flexible stems that allow them to bend without breaking when swept over by the water current, e.g.

cattails

2. Amphibians such as frogs and toads obtain oxygen through their moist skin when in water.

3. Aquatic organisms such as fish have streamlined bodies and fins for movement, and gills for the exchange of gases in water.

4. Also, some aquatic organisms have hooks, suckers or muscular feet that enable them attach to rock surfaces. E.g. mussels and leeches.

5. Aquatic organisms like crocodiles and turtles have webbed feet and strong swimming muscles for swimming.

6. Plants adapted to rivers and streams also have aerenchyma (air-filled tissues) for the supply of air and buoyancy, to keep the leaves closer to the surface where there is sunlight and carbon dioxide.

Figure 3.44: Black Volta River in Ghana

Activity 3.21 Exploring aquatic ecosystems.

1. Embark on a field trip to a nearby river, lake or pond (if possible) or search for videos of rivers, lakes and ponds on the internet.

2. Discuss in groups the definition and nature you observed of rivers, lakes and ponds as you observed from the video or your field trip.

3. Select a specific freshwater body (river, lake or pond) and create a poster or presentation defining your selected water body.

4. Present your work before the class for discussion.

5. Compare your work with presentations on other water bodies from other groups.

Lakes Lakes are typically a large body of standing water surrounded by land. They are larger than ponds with generally no significant water flow. The water level is relatively stable however, the depth varies. It has three distinct zones based on temperature differences: the littoral (shallow), limnetic (open water zone) and profundal (deep water zone). The chemical composition of lakes is influenced by the surrounding geology and climate, i.e. the type of rocks, soil and minerals, as well as weather patterns and temperature. Lakes support a variety of living organisms, including phytoplankton, plants such as water lilies and cattails, various kinds of fish such as catfish and mudfish, perch and trout, birds such as swans, herons, geese, egrets and ducks. Examples of lakes found in Ghana are Lakes Bosomtwe and Volta.

Figure 3.45: Structure of a lake showing different zones.

Adaptations of organisms in lakes

1. Lake plants such as cattails have tall stalks to enable them to reach sunlight and fibrous roots for stability.

2. Fish possess swim bladders, which enable them to maintain buoyancy.

3. Lake plants such as water lettuce have air-filled tissues in the stem, which enable them to float, and large, flat, floating leaves to increase the surface area for absorption of sunlight and for gas exchange.

4. Many lake insects have (hydrophobic) water-repellent surfaces that help them stay dry and float, using the surface tension of the water

5. Some insects, like diving beetles, can be underwater for long periods.

6. Insects like water boatman and backswimmers have air-filled structures for buoyancy.

7. Insects like mayflies and caddisflies have slender bodies for efficient swimming.

Pond Ponds are small, shallow standing bodies of water, typically smaller than lakes.

Ponds have limited water volume and surface area. Water levels fluctuate with precipitation and evaporation. Ponds are often connected to groundwater or nearby water bodies such as the ocean, which could form tidal pools and rock pools.

Due to the shallowness of ponds, light easily penetrates to the bottom to support aquatic life. Ponds serve as important habitats for various living organisms. These include algae, plants (duckweed, water ferns and water lilies), fish (minnows, catfish, goldfish, trout and golden shiners), insects (water beetles, mosquitoes, as well as their larvae), amphibians and birds.

Figure 3.46: A pond, partly covered on the surface by leaves of a water lily.

Adaptations to Pond Habitats

1. Pond dwellers, such as fish, survive in varying oxygen levels, and some can also hide under rocks or mud when the pond water dries out.

2. Pond plants exhibit rapid growth to capitalise on seasonal opportunities like rainfall periods with high nutrient levels to ensure their survival.

3. Amphibians such as toads lay eggs in shallow water, which offers ideal breeding conditions including warmth, oxygen, food availability and protection from predators, thereby increasing reproductive success.

4. Certain insect larvae, like mosquito larvae, possess breathing tubes that allow them to obtain air from the surface of the water.

Activity 3.22 Freshwater Habitat Exploration

1. Embark on a field trip to a nearby river, lake or pond.

2. Observe and record in your notebooks the different organisms you come across (your teacher will provide you with equipment to collect and identify aquatic organisms).

3. Discuss in groups the sampled organisms and their different adaptations to the aquatic habitat where you collected them.

4. Do a presentation of your write-up in class.