Skill Practice: Cause/Effect
Cause and effect words are common in academic writing. Learning to identify them can help you to better understand the logic and organization of university texts.
The two following tables list common cause and effect words. They can be nouns, verbs, or phrases that can connect clauses or sentences. In the example sentences in the Cause Language table, the cause language has been bolded and the cause is underlined.
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Cause Language |
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Type |
Example Cause Words |
Example Sentences |
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Nouns |
cause factor |
One factor that affects biomes is sunlight. |
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Verbs |
cause |
The overuse of fossil fuels may cause global warming. |
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Phrases |
Because of [cause as noun], Due to [cause as noun], As [cause as S+V], If [cause as S+V], When [cause as S+V], Since [cause as S+V], |
Because of the weather, the temperature in the water increased. As their predator’s population grew, the animals struggled to survive. |
In the Effects Language table, the effect language is given and the effect is italicized.
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Effect Language |
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Type |
Example Cause Words |
Example Sentences |
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Nouns |
effect impact result |
The effect could be seen in the increased pollution in the area. |
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Verbs |
affect lead to |
The new housing development has led to decreased habitat for animals. |
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Phrase |
hence [+ effect] so [+ effect] thus [+ effect] |
Thus, wild animals have had to be relocated. |
Practice
The following sentences are taken from “Reading 4” about the global decline of coral reefs. Make note of the cause and effect signal word(s), the cause, and the effect in each sentence. The first sentence is an example. Notice that there may be multiple cause and effect words in one sentence, such as the example.
- The excessive warmth causes the reefs to expel their symbiotic, food-producing algae.
Signal Word: causes Cause: warmth Effect: the reefs to expel their symbiotic, food-producing algae
- If loss of the symbiotic zooxanthellae is prolonged, then the algae and the coral animals die.
Signal Word: _________________ Cause: __________________________________ Effect: __________________________________
- When a coral reef begins to die, species diversity plummets because of animals losing food and shelter.
Signal Word: _________________ Cause: __________________________________ Effect: __________________________________
- Coral reefs are also economically important tourist destinations, so the decline of coral reefs poses a serious threat to coastal economies.
Signal Word: _________________ Cause: __________________________________ Effect: __________________________________
Bonus: In the reading, you’ll find complex sentences where one action is both the cause and the effect. Look at this example below. Can you identify the sophisticated cause and effect relationships?
As global warming, due to fossil fuel emissions, raises ocean temperatures, coral reefs are suffering.
Signal Word: _________________ Cause: __________________________________ Effect: __________________________________
Signal Word: _________________ Cause: __________________________________ Effect: __________________________________
Pre-Reading
The words in bold in the chart are from the following reading. Complete the chart with the different forms of each word.
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NOUN |
VERB |
ADJECTIVE |
ADVERB |
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absorb |
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____ |
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stratification |
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____ |
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decayed |
____ |
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____ |
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relatively |
Given the words above and the reading’s title, what do you think the reading will be about?
Reading 4: Aquatic Biomes [1]
Abiotic Factors Influencing Aquatic Biomes
Like terrestrial biomes, aquatic biomes are influenced by a series of abiotic, non-living, factors. The aquatic medium—water— has different physical and chemical properties than air, however. Sunlight often affects these properties. Even if the water in a pond or other body of water is perfectly clear (there are no suspended particles), water, on its own, absorbs light. As one descends into a deep body of water, there will eventually be a depth which the sunlight cannot reach. While there are some abiotic and biotic factors in a terrestrial ecosystem that might obscure light (like fog, dust, or insect swarms), usually these are not permanent features of the environment. The importance of light in aquatic biomes is central to the communities of organisms found in both freshwater and marine ecosystems. Additionally, the thermal properties of water (rates of heating and cooling) are significant to the function of marine systems and have major impacts on global climate and weather patterns. Marine systems are also influenced by large-scale physical water movements, such as currents; these are less important in most freshwater lakes.
The ocean is categorized by several areas or zones (Figure 15). All of the ocean’s open water is referred to as the pelagic realm (or zone). The benthic realm (or zone) extends along the ocean bottom from the shoreline to the deepest parts of the ocean floor. Within the pelagic realm is the photic[2] zone, which is the portion of the ocean that light can penetrate (approximately 200 m or 650 ft). At depths greater than 200 m, light cannot penetrate; thus, this is referred to as the aphotic zone. The majority of the ocean is aphotic and lacks sufficient light for photosynthesis. The deepest part of the ocean, the Challenger Deep (in the Mariana Trench, located in the western Pacific Ocean), is about 11,000 m (about 6.8 mi) deep. To give some perspective on the depth of this trench, the ocean is, on average, 4267 m or 14,000 ft deep. These realms and zones are relevant to freshwater lakes as well.
Marine Biomes
The ocean is the largest marine biome. It is a continuous body of salt water that is relatively uniform in chemical composition; it is a weak solution of mineral salts and decayed biological matter. Within the ocean, coral reefs are a second kind of marine biome. Estuaries, coastal areas where salt water and fresh water mix, form a third unique marine biome.
Ocean
The physical diversity of the ocean has a significant impact on plants, animals, and other organisms. The ocean is categorized into different zones based on how far light reaches into the water. Each zone has a distinct group of species adapted to the biotic and abiotic conditions particular to that zone.
The intertidal zone, which is the zone between high and low tide, is the oceanic region that is closest to land (Figure 15). Generally, most people think of this portion of the ocean as a sandy beach. In some cases, the intertidal zone is indeed a sandy beach, but it can also be rocky or muddy. The intertidal zone is an extremely variable environment because of tides.
Organisms are exposed to air and sunlight at low tide and are underwater most of the time, especially during high tide. Therefore, living things that thrive in the intertidal zone are adapted to being dry for long periods of time. The shore of the intertidal zone is also repeatedly struck by waves, and the organisms found there are adapted to withstand damage from the pounding action of the waves (Figure 16). The exoskeletons of shoreline crustaceans (such as the shore crab, Carcinus maenas) are tough and protect them from drying out and wave damage. Another consequence of the pounding waves is that only a few types of algae and plants establish themselves in the constantly moving rocks, sand, or mud.
The neritic zone (Figure 15) extends from the intertidal zone to depths of about 200 m (or 650 ft) at the edge of the continental shelf. Since light can penetrate this depth, photosynthesis can occur in the neritic zone. The water here contains silt and is well-oxygenated, low in pressure, and stable in temperature. Phytoplankton and floating Sargassum (a type of free-floating marine seaweed) provide a habitat for some sea life found in the neritic zone. Zooplankton, protists, small fishes, and shrimp are found in the neritic zone and are the base of the food chain for most of the world’s fisheries.
Beyond the neritic zone is the open ocean area known as the oceanic zone (Figure 15). Within the oceanic zone there is thermal stratification where warm and cold waters mix because of ocean currents. This stratification is part of what determines the two main realms and three main sub-zones within the ocean. The pelagic realm, also known as the open ocean, is divided into different zone depending on the depth and amount of sunlight they get.
Beneath the pelagic realm is the benthic realm, the deep-water region beyond the continental shelf (Figure 15). The bottom of the benthic realm is comprised of sand, silt, and dead organisms. Temperature decreases, remaining above freezing, as water depth increases. This is a nutrient-rich portion of the ocean because of the dead organisms that fall from the upper layers of the ocean. Because of this high level of nutrients, a diversity of fungi, sponges, sea anemones, marine worms, sea stars, fishes, and bacteria exist.
The deepest part of the ocean’s open water is the abyssal zone, which is at depths of 4000m or greater. The abyssal zone (Figure 15) is very cold and has very high pressure, high oxygen content, and low nutrient content. There are a variety of invertebrates and fishes found in this zone, but the abyssal zone does not have plants because of the lack of light. Hydrothermal vents are found primarily in the abyssal zone; chemosynthetic bacteria utilize the hydrogen sulfide and other minerals emitted from the vents. These chemosynthetic bacteria use the hydrogen sulfide as an energy source and serve as the base of the food chain found in the abyssal zone.
Coral Reefs
Coral reefs are ocean ridges formed by marine invertebrates living in warm shallow waters within the photic zone of the ocean. They are found within 30˚ north and south of the equator. The Great Barrier Reef is a well-known reef system located several miles off the northeastern coast of Australia. Other coral reef systems are fringing islands, which are directly adjacent to land, or atolls, which are circular reef systems surrounding a former landmass that is now underwater. The coral organisms (members of phylum Cnidaria) are colonies of saltwater polyps that secrete a calcium carbonate skeleton. These calcium-rich skeletons slowly accumulate, forming the underwater reef (Figure 17). Corals found in shallower waters (at a depth of approximately 60 m or about 200 ft) have a mutualistic relationship with photosynthetic unicellular algae. The relationship provides corals with the majority of the nutrition and the energy they require. The waters in which these corals live are nutritionally poor and, without this mutualism, it would not be possible for large corals to grow. Some corals living in deeper and colder water do not have a mutualistic relationship with algae; these corals attain energy and nutrients using stinging cells on their tentacles to capture prey.
It is estimated that more than 4,000 fish species inhabit coral reefs. These fishes can feed on coral, the cryptofauna (invertebrates found within the calcium carbonate substrate of the coral reefs), or the seaweed and algae that are associated with the coral. In addition, some fish species inhabit the boundaries of a coral reef; these species include predators, herbivores, or planktivores. Predators are animal species that hunt and are carnivores or “flesh eaters.” Herbivores eat plant material, and planktivores eat plankton.
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Evolution Connection – Global Decline of Coral Reefs It takes a long time to build a coral reef. The animals that create coral reefs have evolved over millions of years, continuing to slowly deposit the calcium carbonate that forms their characteristic ocean homes. Bathed in warm tropical waters, the coral animals and their symbiotic algal partners evolved to survive at the upper limit of ocean water temperature. Together, climate change and human activity pose dual threats to the long-term survival of the world’s coral reefs. As global warming, due to fossil fuel emissions, raises ocean temperatures, coral reefs are suffering. The excessive warmth causes the reefs to expel their symbiotic, food-producing algae, resulting in a phenomenon known as bleaching. When bleaching occurs, the reefs lose much of their characteristic color; if loss of the symbiotic zooxanthellae is prolonged, then the algae and the coral animals die. Rising levels of atmospheric carbon dioxide further threaten the corals in other ways; as CO2 dissolves in ocean waters, it lowers the pH and increases ocean acidity. As acidity increases, it interferes with the calcification that normally occurs as coral animals build their calcium carbonate homes. This makes the coral more vulnerable to breakage and death. When a coral reef begins to die, species diversity plummets because of animals losing food and shelter. Coral reefs are also economically important tourist destinations, so the decline of coral reefs poses a serious threat to coastal economies. Human population growth has damaged corals in other ways, too. As human coastal populations increase, the runoff of sediment and agricultural chemicals has increased, too, causing some of the once-clear tropical waters to become cloudy. At the same time, overfishing of popular fish species has allowed the predator species that eat corals to go unchecked. Although a rise in global temperatures of 1–2˚C (a conservative scientific projection) in the coming decades may not seem large, it is very significant to this biome. When change occurs rapidly, species can become extinct before evolution leads to new adaptations. Many scientists believe that global warming, with its rapid (in terms of evolutionary time) and inexorable increases in temperature, is tipping the balance beyond the point at which many of the world’s coral reefs can recover. |
Estuaries: Where the Ocean Meets Fresh Water
Estuaries are biomes that occur where a source of fresh water, such as a river, meets the ocean. Therefore, both fresh water and salt water are found in the same vicinity; this mixing results in a diluted saltwater. Estuaries form protected areas where many of the young offspring of crustaceans, mollusks, and fish begin their lives. Salinity, the saltiness, is a very important factor that influences the organisms and the adaptations of the organisms found in estuaries. The salinity of estuaries varies and is based on the rate of flow of its freshwater sources. Once or twice a day, high tides bring salt water into the estuary. Low tides occurring at the same frequency reverse the current of salt water.
The short-term and rapid variation in salinity due to the mixing of fresh water and salt water is a difficult physiological challenge for the plants and animals that inhabit estuaries. Many estuarine plant species are halophytes: plants that can tolerate salty conditions. Halophytic plants are adapted to deal with the salinity resulting from saltwater on their roots or from sea spray. In some halophytes, filters in the roots remove the salt from the water that the plant absorbs. Other plants are able to pump oxygen into their roots. Animals, such as mussels and clams (phylum Mollusca), have developed behavioral adaptations that expend a lot of energy to function in this rapidly changing environment. When these animals are exposed to low salinity, they stop feeding, close their shells, and switch from aerobic respiration (in which they use gills) to anaerobic respiration (a process that does not require oxygen). When high tide returns to the estuary, the salinity and oxygen content of the water increases, and these animals open their shells, begin feeding, and return to aerobic respiration.
Reading Comprehension
Choose the best answer to the following questions.
- Where would you expect to find the most photosynthesis in an ocean biome?
- aphotic zone
- abyssal zone
- benthic realm
- intertidal zone
- A key feature of estuaries is:
- low light conditions and high productivity
- salt water and fresh water
- frequent algal blooms
- little or no vegetation
Match the zones or regions in the ocean with their descriptions.
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3. ______ abyssal zone |
a) part of the ocean where no light penetrates
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4. ______ aphotic zone |
b) deepest part of the ocean at depths of 4000 m or greater
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5. ______ benthic realm |
c) open ocean waters that are not close to the bottom or near the shore
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6. ______ photic zone |
d) portion of the ocean that light can penetrate
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7. ______ pelagic realm
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e) part of the ocean that extends along the ocean bottom from the shoreline to the deepest parts of the ocean floor |
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Hint: Use the reading skill of looking for cause and effect language to answer these questions. You may need to go back and look for those clues. Then, answer the questions below. |
Answer the questions in your own words.
- How do tides affect organisms in the intertidal zone?
- How is the neritic zone different from the oceanic zone in terms of location, organisms, etc.?
- Why is there thermal stratification in the oceanic zone?
- What causes coral bleaching? What are some of its effects?
Read the statements. Put T for True or F for False. If the statement is false, correct the error to make the statement true.
- ______ The sea life in the neritic zone is the foundation for the food chain for the world’s fisheries.
- ______ The abyssal zone is very cold with low oxygen content and low nutrient content.
- ______ Coral reefs are ocean ridges created by marine invertebrates living in cool shallow waters.
- ______ Human population growth has damaged coral reefs due to the runoff of agricultural chemicals into the oceans.
- ______ The salinity of estuaries fluctuates based on the flow of its salt water sources.
Vocabulary Practice
Complete the sentences below using the words in the box.
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absorb acidity adjacent decay dual habitat nutrient penetrate relatively stratification |
- The animals were endangered in part because of the loss of their _________________________, which made it difficult for them to find shelter.
- Dark colors _________________________ a lot of light.
- The animal must have died several days ago judging by the amount of _________________________.
- Planting trees _________________________ to a river can drastically change the temperature of the water and help ensure a healthy environment for fish.
- The _________________________ in society is well established, and few people interact with people who are different from them.
- The scientist played a _________________________ role as both an educator and a researcher.
- Without proper food intake, organisms will become _________________________ deficient and may even die.
- Light can’t _________________________ to the bottom of the ocean.
- After the chemical spill, the water’s _________________________ increased significantly.
- The fish were introduced to the lake a decade ago, so they are a _________________________ recent addition.
Reading Discussion
Discuss these questions with your classmates.
- Describe the conditions and challenges facing organisms living in the intertidal zone. What do you think is the most difficult zone in the aquatic biome to survive in? Why?
- Summarize the effects that climate change and human activity are having on the world’s coral reefs. What should governments do to address this issue?
- Explain how plants and animals in estuaries have adapted to deal with salinity. What other plants or animals do you know of that have adapted to their environment?