Chapter 13: Marine Ecosystems
The lowering of the pH of the oceans is known as ___________. A) salting B) reduction C) alkalinity D) acidification E) chloride shifting
D) acidification
The largest percentage of destroyed coral reefs is found in the ___________. A) Indian Ocean B) Pacific Ocean C) Caribbean Sea D) Atlantic Ocean E) Mediterranean Sea
A) Indian Ocean
As the atmospheric concentration of CO2 increases, the amount of CO2 absorbed by the oceans (pCO2) also increases. This type of relationship is ____. A) directly proportional B) inversely proportional C) negative feedback D) positive feedback E) None of the above
A) directly proportional
It is estimated that ___ of all ocean species spend some portion of their life in a coral reef. A) 10% B) 25% C) 50% D) 75% E) 90%
B) 25%
Coral reefs are limited to shallow water. Rising sea levels will affect them because ____. A) they require the lower salinity found in shallow waters B) there are more nutrients found in shallow water C) their symbiotic zooxanthellae require light to survive D) they require coastal upwellings of CO2 in order to survive E) it is too difficult for them to build reefs in deeper water
C) their symbiotic zooxanthellae require light to survive
Why is proximity to land such an important factor influencing the abundance of life in ocean zones? Provide an example to support your reasoning.
The closer an ocean region is to land and to estuaries, the more nutrient rich that region will be and the more productive its community. Estuaries are known as "the nurseries of the sea" because they are where many species come to spawn.
Describe two strategies that reduce threats to ocean ecosystems and their beneficial effects. (Refer to Infographic 13.8.)
(1) Limit coastal development especially in vulnerable areas. This keeps the areas intact and also reduces exposure to land-based pollution that can harm sea life. (2) Reduce use of fossil fuels and transition to non-fossil fuel-based energy sources. This will reduce the amount of anthropogenic CO2 released, which will reduce the CO2 available to be absorbed by oceans and thus slow ocean acidification and warming.
What effect do acidic ocean waters have on shells made of calcium carbonate? A) increased dissolution (dissolving) of calcium carbonate shells B) decreased dissolution (dissolving) of calcium carbonate shells C) shells grow at faster rates D) shells overly calcify E) acidic ocean waters have no effect on shells made of calcium carbonate.
A) increased dissolution (dissolving) of calcium carbonate shells
Which of the following changes will have the greatest global effect on coral reefs despite their location? A) increased water temperatures from anthropogenic CO2 emissions B) increased salinity from desalination of ocean water for human use C) increased oxygen concentrations from algal blooms due to nutrient pollution D) increased predation on native coral reef fish by non-native lionfish E) increased sediment pollution from clear-cut inland forests that smother reefs
A) increased water temperatures from anthropogenic CO2 emissions
Which ecosystem has the greatest variety of flora and fauna? A) marine B) freshwater lake C) prairie D) tropical forest E) desert
A) marine
When changes caused by an initial event, trigger events that then reverse that response (e.g. changes brought on by warming lead to cooling), this is a(n) ___. A) negative feedback cycle B) positive feedback cycle C) amplification D) dissolution E) balanced feedback cycle
A) negative feedback cycle
The majority of coral reefs on Earth are found between _____ and _____ of the equator. A) 10 N; 10 S B) 30 N; 30 S C) 50 N; 50 S D) 10 W; 10 E E) 30 W; 30 S
B) 30 N; 30 S
Which of the following statements is/are TRUE regarding reducing threats to marine ecosystems? A) MPAs do not improve marine ecosystems; it is impossible to maintain community connections, and ocean ecosystems are not very resilient. B) A transition to non-fossil fuel-based energy sources will reduce the amount of anthropogenic CO2 released and slow ocean acidification and warming. C) Given rising sea levels, it is less critical to reduce nutrient or toxic pollution, as the larger volume of water will dilute the pollutants. D) Overfishing is not the problem: it is fishing techniques. We can keep fishing at current rates and improve ocean ecosystems if we change how we fish. E) All of the above statements are true.
B) A transition to non-fossil fuel-based energy sources will reduce the amount of anthropogenic CO2 released and slow ocean acidification and warming.
Which factor in the ocean is key in determining environmental conditions? A) space B) depth C) predators D) pressure E) biota
B) depth
Nutrient rich areas where shallow rivers meet the ocean are known as ______. A) intertidal zones B) estuaries C) coral reefs D) abyssal zones E) open ocean
B) estuaries
The deepest zone in the ocean is the ____________. A) abyssal B) hadal C) bathypelagic D) epipelagic E) mesopelagic
B) hadal
Where does the majority of ocean pollution come from? A) offshore mining and oil drilling activities B) human activities on land that pollute runoff that enters ocean ecosystems C) accidental oil spills from oil tankers transporting crude oil D) deliberate dumping of litter in the ocean by cruise ships E) atmospheric contaminants that enter the ocean via precipitation
B) human activities on land that pollute runoff that enters ocean ecosystems
What are MPAs? A) fishing areas for commercial fishermen B) places where fishing and other human activities are limited C) delicate intertidal communities D) areas that are overrun with invasive species E) places near shorelines that have been extremely polluted by sediment
B) places where fishing and other human activities are limited
Which of the following is NOT a major threat to ocean ecosystems? A) overfishing B) plate tectonics C) pollution D) rising sea levels E) invasive species
B) plate tectonics
The exoskeleton of coral is mostly composed of ________. A) nitrogen B) aluminum C) calcium carbonate D) silicon E) iron
C) calcium carbonate
In some areas of Florida, divers who remove non-native lionfish from coral reefs are eligible for a $10 000 prize. This is because ___________. A) lionfish produce a chemical in great demand in the pharmaceutical industry B) lionfish exclusively eat grouper, a fish considered a delicacy in fine dining C) lionfish aggressively kill native fish outright or outcompete them when foraging D) lionfish populations are dwindling in some parts of their range and this is a way to repopulate them in those regions E) lionfish are in high demand by aquarium enthusiasts
C) lionfish aggressively kill native fish outright or outcompete them when foraging
Describe the complex relationship that coral have with zooxanthellae ('zooks')
Coral live in a mutualistic relationship with zooxanthellae. The two species share nutrients. The zooxanthellae raise the pH of the coral cells which help the coral lay down its coral skeleton. Corals provide the zooxanthellae with nutrients and carbon dioxide for photosynthesis. Zooxanthellae provide the coral with food made during photosynthesis.
The NOAA estimates that ______ of coral reefs worldwide are threatened by either human activity or environmental changes. A) 10% B) 25% C) 50% D) 75% E) 90%
D) 75%
Why do corals become 'bleached'? A) They become exposed to excessive ultraviolet radiation. B) They are effected by increasing water temperatures. C) They expel their zooxanthellae when stressed. D) All of the above are correct. E) B and C only are correct.
D) All of the above are correct.
Which statement about coral reefs is FALSE? A) Overfishing is a major cause of coral reef destruction. B) Coral reefs serve as a source of current and potential medicines. C) Coral reefs help protect shorelines from storms. D) Coastal development does not affect coral reefs because they develop far away from the shore. E) Most coral reefs are found between 30 degrees north latitude and 30 degrees south latitude.
D) Coastal development does not affect coral reefs because they develop far away from the shore.
When a solution becomes acidic it contains more of which of the following? A) H2O B) OH- C) CH4 D) H+ E) O2
D) H+
Which ocean zone has the highest rate of photosynthesis? A) abyssal B) hadal C) bathypelagic D) epipelagic E) meso
D) epipelagic
You would expect to find barnacles, starfish, and mussels in which of the ocean zones listed below? A) abyssal B) hadal C) bathypelagic D) intertidal E) All of the above
D) intertidal
The greatest threat to coral reefs, of the following, is ___________. A) marine-based pollution B) inland pollution C) coastal development D) overfishing E) None of the above are threats
D) overfishing
In which of the following is the human activity correctly matched to its consequence for marine ecosystems? A) drill for oil---coral bleaching B) fertilizer use---ocean acidification C) fishing with dynamite---algal blooms D) release of ballast water from ships---introduction of invasive species E) None of the above
D) release of ballast water from ships---introduction of invasive species
Where would you find the highest concentration of coral reefs? A) freshwater lakes B) freshwater streams C) temperate marine areas D) tropical marine areas E) terrestrial areas
D) tropical marine areas
Why is depth such an important factor influencing the abundance of life in ocean zones? Provide examples to support your reasoning.
Depth is important because most of the sunlight that enters the ocean is absorbed in the first 10 metres of the water column. Since sunlight is essential to photosynthesis, surface and shallow regions of the ocean are more productive than deeper regions. For example, the majority of ocean life, including coral reefs, is found in coastal waters on shallow continental shelves. The farther you move away from the coast into deeper waters, the less life there is.
More than ______ of the oceans today contain at least one invasive species. A) 20% B) 40% C) 50% D) 60% E) 80%
E) 80%
Fishing pressure (overexploitation) has eliminated ______ of top trophic level predators in the oceans. A) 15% B) 30% C) 55% D) 75% E) 90%
E) 90%
Coral live in a mutualistic relationship with zooxanthellae ('zooks'), which _____. A) are photosynthetic algae B) slightly raise the pH of coral cells C) act as parasites, draining nutrients from coral cells D) All of the above E) A and B only
E) A and B only
Which of the following is NOT a source of human impact on marine ecosystems? A) fishing practices such as bottom trawling B) resort development in coastal areas C) agricultural use of chemical fertilizers and pesticides D) offshore oil drilling E) All of the above are examples of human impact on marine ecosystems.
E) All of the above are examples of human impact on marine ecosystems.
How do zooxanthellae affect coral? A) They give corals their colour. B) They provide coral with food via sugars they make during photosynthesis. C) They provide coral with a place to attach to the ocean floor. D) All of the above are correct. E) Only A and B are correct.
E) Only A and B are correct.
The ocean is so vast that it is hard to imagine that human activities could harm it. However the evidence of human impact is unmistakable. Explain the nature of marine ecosystem destruction from pollution and overfishing
Human activities harm marine ecosystems in a variety of ways, with major threats coming from pollution and overfishing. Oceans receive pollution from land (via runoff) and from the atmosphere (via precipitation). Millions of metric tons of trash, including plastic and fishing nets, entangle and kill marine organisms. Less visible contaminants like fertilizers, pesticides, and human sewage also cause problems. Nutrient runoff from agricultural areas causes algal blooms which smother corals and block sunlight, reducing photosynthesis. Pathogens in untreated sewage contaminate shellfish and other seafood, posing a threat to public health. Offshore oil drilling not only pollutes as a result of oil spills but the combustion of fossil fuels releases CO2 into the Earth's atmosphere which is then absorbed by the world's oceans, leading to ocean acidification. But it is overfishing that is currently the biggest threat to oceans; about 90% of top trophic-level predators have already been eliminated by overexploitation. Fishing pressure also inflicts other wounds such as the destruction of sea beds by bottom trawling and the destruction of reefs from the use of dynamite and cyanide sprays.
What are invasive species? Discuss the possible causes and the ecological impact of this threat to ocean ecosystems, using the lionfish as an example.
Invasive species are non-native species that are introduced into ocean ecosystems in which they do not belong and where they can wreak major havoc. More than 80% of ocean harbours around the world now host at least one invasive species which may have arrived in the ballast water of ships, have been accidentally released from aquaculture pens, or have escaped while being moved as part of the aquarium trade. Take the lionfish as an example. It was an escapee from aquaria and now poses a significant threat to coral reefs in places like the Bahamas and Florida. Lionfish are aggressive and poisonous predators and either outright kill native fish or outcompete them when foraging. When they are introduced to a coral reef, the survival of native fish can drop by as much as 80%.
Anthropogenic carbon dioxide emissions have reduced ocean pH by about 0.1. Why is this degree of acidification of the ocean such a problem?
Normal seawater has an average pH of 8.2. Since the Industrial Revolution, the average pH has dropped to 8.1. Since the pH scale is logarithmic, a decline of 0.1 corresponds to a 30% increase in ocean water acidity. Even a decline of a few tenths of a pH unit can alter the ability of marine organisms to produce shells. At a pH of 7.6, most shells would dissolve quickly. The projected pH for 2100 is 7.7. Marine ecosystems contain vast biodiversity, and experts say that the ocean acidification changes are happening too fast for many organisms to adapt. The loss of that biodiversity will be a catastrophe.
What is ocean acidification and how are humans causing it?
Ocean acidification is the name scientists chose to describe the current catastrophe that is occurring in ocean waters—the decrease in pH of ocean water due to increased amounts of atmospheric carbon dioxide. Since the Industrial Revolution, humans have been burning fossil fuels and releasing carbon dioxide into the atmosphere. Because the ocean and atmosphere are in direct contact on over 75% of Earth's surface, the carbon dioxide emitted into the atmosphere eventually winds up in the ocean. Increased levels of carbon dioxide in the ocean cause chemical reactions to occur which lower the pH of ocean waters.
You have been given the task of monitoring the health of a coral reef. Over the years, you have documented a decrease in the biodiversity of life in the reef. What might be some of the reasons why the reef is suffering?
The introduction of invasive species can have a major impact on the health of a reef. Lionfish have the ability to reduce native fish populations by 80%. Changes in the temperature and pH of the water can cause coral bleaching which would reduce the productivity of the reef, reducing the number of organisms the reef could support. Illegal use of dynamite, cyanide, or bottom trawling could also damage the reef. Other threats include overfishing, pollution, debris, and fish collection.
What do white patches on coral reefs indicate? Discuss the possible causes and the ecological impacts of this phenomenon. (Refer in part to Infographic 13.6.)
The white area indicates bleached coral. A healthy coral lives in a symbiotic relationship with its algal partners (the zooxanthellae, or "zooks"). Corals provide their resident zooks with nutrients and CO2 for photosynthesis as well as protection of the calcium carbonate skeletons of coral reefs. Zooks, in turn, provide the coral polyps with food (sugars made during photosynthesis). When corals get stressed, they expel their zooxanthellae. This event is known as coral bleaching because when it happens the coral turns bone white (as the zooxanthellae also give the corals their colours). Environmental stressors such as warmer seawater temperatures, pollution, and coral diseases are all potential causes of coral bleaching. Bleaching could be an adaptation that allows the coral to take up a different species of zooks, one that can tolerate the particular environmental stress, and coral may survive for a few months without the zooks. But since these algae are necessary for the survival of the coral, when the zooxanthellae die, the coral slowly dies if not recolonized. Loss of coral reefs means loss of marine habitat for many organisms and loss of ecosystem services, including: protection of coastal areas from storms, purification of the water (many reef occupants are filter feeders), provision of recreational opportunities, support of important commercial fisheries, and a source of current and potential medicines such as antibiotics and anticancer drugs.
