Coral Reefs

Map of the reefs on Earth

Red = Fringing reefs / Green = Barrier reefs / Orange = Atolls

1. How is each reef structure formed? A reef structure is form by what is known as “Coral.” Corals are different groups of cnidarians but only some have the ability to build reefs. In reef-building, corals/polyps produce calcium carbonate skeletons, where as billions of these tiny skeletons unite as one to form a massive reef. The most important reef builders are the scleractinian corals, also known as the "stony" or "true" corals. Most reef-building corals contain symbiotic zooxanthellae. It helps the corals make their calcium carbonate skeletons. However, as much as for the corals, it is the help of the symbiotic zooxanthellae that construct the reefs framework, where as without it-there would be no reefs.

2. Where is each reef structure found? There are three different types of reefs. They are called the fringing reef, barrier reef and atoll. The fringing reefs are located close to shore and are seperated from land by shallow water or no water at all. Barrier reefs are lacated farther from shore seperated from land by a lagoon ten meters deep. Atolls are also found far offshore. They are ring-shaped reefs that enclose a circular lagoon and are also known as coral islands.

3. What is the trophic structure of a reef? The trophic structure of a reef is the reprocess of nutrients, where as then the ocean water lacks nutrients. However, the reef is able to provide some of its own nutrients, which make it very productive. Coral reefs are amongst those who have the highest rate of nitrogen fixation. The nitrogen is fixed on the reef, where as the zooplankton and nutrients that transpire in the water are used efficiently.

4. How does the location and type of reef influence the trophic structure? It is theorized that each type of reef and/or an entire reef structure differentiates in age. The fringing reef is known to be the youngest, where as the corals colonize at the shallow area close to the land. If the sea levels rise or the land subsides, the reef structure keeps up with the changing depths by growing upward. A shallow area with no coral growth will then form behind the main reef, called a lagoon; proceeding to a barrier reef. However, if the sea level or land subsides too much, it will cause the land to disappear below the water surface and an atoll will form. Each type of reef is also divided into various zones within each reef.

5. Examples of the types of corals found on reefs. Corals are divided into two kinds but both are stationary on the ocean bottom. There are the hard corals and the soft corals. The hard corals are considered to be the brain, star, staghorn, elkhorn and pillar corals, which have rigid exoskeletons, or corallites, that protect their soft delicate bodies. The soft corals on the other hand are also known as the "gorgonians," which are the sea fans, sea whips, and sea rods, that sway with the currents and lack an exoskeleton.

6. Examples of competition, predation, and grazing. *Competition is the interaction that results when a resource is in short supply and one organism uses the resource at the expense of another. For example: Sessile coral reef organisms must compete for space, however, corals and seaweeds compete for light as well. The two effective ways in which corals compete for space are by overgrowing their neighbors and by directly attacking them. *Predation is the act of an animal, or predator, eating another organism or prey, where as a top predator is one that feeds at the top of the food chain. When predation takes place on corals, it only occurs when a variety of animals eat corals, but instead of killing the coral and eating it entirely, most coral predators eat or bite off pieces of individual polyps. This leads to the survival of the coral colony, where as it can then grow back the portion that was eaten. *A grazer is an organism that feeds primarily on plants, where as grazing is the process of transplantation, removal and caging. A damselfishe is an example of a grazer. It grazes on seaweeds inside territories that they vigorously defend, chasing away other fishes that happen to venture inside, where as their territories are so called their "farm."

SIMILARITIES

*have all types of coral reefs and also grow several types of coral

*home to many different organisms

*contain reef flats and reef slopes

DIFFERENCES*

*atolls grow on top of sunken volcanic land and grown around lagoons

*fringing reefs form along the coastline

*barrier reefs separate lagoons

Critical Thinking Questions

Chapter 19 Critical Thinking Question 1.) Most maritime cultures are either long gone or have been radically modified by others. Which elements of a rapidly changing maritime culture do you predict would be the first to disappear? Which would tend to remain unchanged the longest? *Some of the early stages of human evolution were spent on the seashores. Our ancestors were coastal inhabitants who frequently waded in the water searching for food. Over time, humans then began to learn how to fish using nets, traps, and other, more sohisticated techniques. In the mean time, many of the maritime cultures that manage to survive have been greatly modified and transformed. Only traces may remain of times when life depended on the cycles of the ocean.

Chapter 18 Critical Thinking Question 1.) Waste from duck farms used to wash into two shallow-water bays on Long Island, New York. The wastes, rich in nutrients such as nitrate and phosphate, polluted the water. What do you suppose was the immediate effect of the pollutants? Can you speculate on the likely effects on the commercially valuable shellfish of the area. *Fertillizers in agricultural runoff and sewage are major sources of nitrate, phosphate, and other nutrients to the marine environment. When the fossil fuel combustion is released into the atmosphere, it becomes another source of nitrogen. Thus, people have come to dominate the nitrogen cycle, and the situation will then intensify because of the usage of fertilizers, fossil fuel combustion, and other human activities that increase nutrient inputs to the open water.



Chapter 14 Critical Thinking Question 1.) What factors might account for the fact that the vast majority of atolls occur in the Indian and Pacific oceans and that atolls are rare in the Atlantic? *Atolls are strongly influenced by trade winds, which blows from latitudes of about 30 degrees towards the equator and there are more warm surface currents in the Indian and Pacific Ocean than in the Atlantic Ocean.



3.) There are only a few reefs off the northeast coast of Brazil, even though it lies in the tropics. How would you explain this? *Not all reef building corals can form in the tropics especially where rivers bring in a lot of silty sediment, which is uncommon to corals.



2.) Scientist predict that the ocean will get warmer and the sea level will rise as a result of an intensified greenhouse effect. How might this affect coral reefs? *The earth is getting wamer because of global warming. The change will affect and flood our ecosystem such as the mangrove forest and the estuaries, where as the coral reefs may not grow fast enough to keep up with the rising sea levels.



Chapter 9 Critical Thinking Question 1.) Sea turtles have disappeared from many regions, and one way of trying to save them is to reintroduce them to areas where they have been wiped out. This is done by reburying eggs or by releasing newborn baby turtles on beaches. Why are eggs reburied or baby turtles released instead of fully grown individuals?

*Eggs are buried under the sand, where as it hatches about after 60 days of incubation in the sand. Once born, the baby turtles must then dig themselves out of the sand and safely crawl all the way back into the water. Green turtles and other sea turtles have many enemies/predators. The eggs are often eaten by dogs, ghost crabs, wild pigs, and other animals, where as the hatchings are even more easy prey for land crabs and birds, especially during the day. Even more young turtles are lost in the water, where they are taken by a variety of fishes and sea birds.



Chapter 8 Critical Thinking Question 1.) Hagfishes and lampreys are the only living representatives of a very ancient group. Why do you suppose there are still some of these jawless fishes around? *Jawless fishes are known to be the most primitive fishes still living today. They have exsited through the years because of their feeding habits. They mostly feed on dead or dying fishes, which is impossible of becoming to be extinct.



2.) A deep-water shark, new to science, is collected for the first time. The specimen is studied in detail, but its stomach is empty. How could you get a rough idea of its feeding habits? The specimen is a female, and its reproductive tract is found to contain 20 eggs. Can you tell the type of developement characteristic of this species? *In order to determine the feeding habits of the deep-water shark, you must study the jaws. Not all living species of sharks consists of the same body characteristics, but majority are known to contain rows of numerous sharp, often triangular teeth. This is one major characteristic of sharks since they are known to be massive in predatory feeding. However, whale sharks differ in that they are filter feeders, which means an empty stomach; so the type of developement characteristics of the 20 eggs is yet to be unknown. There are two different types of sharks which may have an affect on the developement. One is the oviparous shark, where as the yolk is an essential need to provide energy for atleast several months of development and because without this amount of time, the eggs won't be fully developed. The second one is the vivparous shark; its nutrition is provided by its direct contact with the reproductive tract of the female.



3.) Individuals of some species of bony fishes change sex, some to maintain more males than females, others more females than males. What are the advantages and disadvantages of each situation? Are there any advantages and disadvantages in having an equal number of males and females? *One advantage of maintaining more males than females is that there will be more chances of having a dominant male. Since a dominant male is needed to triger these changes (protandry and protogyny). A disadvantage of this situation will be that with less female, there will be less chances of reproduction. Whereas, this would be an advantage of having more females than males. And as for having an equal number of males and females, I think that there will be no advantages or disadvantages, since everything will turn out to be average.



Chapter 7 Critical Thinking Question 2.) Cephalopods, the squids, octopuses, and allies, show a much higher degree of structural and behavioral complexity than the other groups of mollusks. What factors triggered the evolution of these changes? A rich fossil record among cephalopods shows that once they were very common and even dominant in some marine environments. Now there are only about 650 living species of cephalopods, far fewer than gastropods. In the end, were cephalopods successful? What do you think happened along the way? *The need for movement and a more active hunting lifestyle were the factors/changes that triggered evolution. Cephalopods are greatly outnumbered by so many other organisms but is still in existence today, where as I believe they are successful. The difference between a gastropod and a cephalopod is that a gastropod has a soft body, therefore they need something hard to protect themselves from predators. Cephalopods on the other hand, have a quick paced movement and have developed tactics to confuse or harm predators. However, not all are the same, where as, some may be slower and weaker than others to have survived their predators and the others may be more dominant and successful in the world of survival.



Chapter 6 Critical Thinking Question 2.) Only very few flowering plants have invaded the oceans, but those that have are very successful. What are some possible reasons for the small number of marine flowering plants? How do those that have taken the step manage to thrive in some environments? *There are only a few species of flowering plants that have mange to invade and live in the ocean. For an example the "Seagrass flower". It is the closest relatives and members of the lily family, which shows that seagrass flowers evolved from land plants. They have very well adapted to life in the marine environment though instead of attracting insects for pollination like any ordinary flower, the pollen is rather more carried by the water currents. The tiny seeds result from successful fertilization, where as they are dispersed by the water currents, feces of the fish and other organisms that browse on the plants.

Chapter 5 Critical Thinking Question 1.) Scientists use the particular structure of nucleic acids and other chemical differences to separate the archaea from the bacteria. Can you think of other characteristics that could be used to distinguish not only between these two domains but also between them and Protists? *There are two prokaryotic domains,which are the Bacteria and Archaea. They have important differences that include the chemistry of their cell walls, plasma membranes, and the cellular machinery that manufactures proteins. They are the most simpliest and primitive form of life. Protists are mostly aquatic primary producers that lack the specialized tissues of plants. They range in size and complexity from single cells to large multicellular seaweeds.

Chapter 4 Critical Thinking Question 1.) During the day, algae carry out both photosynthesis and respiration, but at night, when there is no light, they can only perform respiration. Small, isolated tide pools on rock shores are often inhabited by thick growths of seaweeds, which are algae. Would you expect the amount of oxygen in the water to differ between night and day? How? *Yes, I would expect the amount of oxygen in the water to differ between night and day because i would expect that the amount of energy produce during day decrease at night because there is no source of sun light and with out solar energy, the autotrophs would not or then cant produce oxygen.

Chapter 3 Critical Thinking Question 4.) Most tsunamis occur in the Pacific Ocean, as indicated by the map in the "Waves that Kill" boxed reading. How would you explain this? *Tsunamis are caused from earthquakes, landslides, volcanoes, and other seismic disturbances of the sea floor, where as 85% of all tsunamis occured in the Pacific Ocean. Around the rim of the Pacific Ocean are many volcanoes, which is known as the Pacific Rim of Fire. These eruptions are one of the main causes of the seismic activity in the Pacific Ocean, which causes the tsunami.

Chapter 2 Critical Thinking Question 2.) Why are most oceanic trenches found in the Pacific Ocean? *Most oceanic trenches are found in the Pacific Ocean because of geolocical activitiy around its feature. Collision between the oceanic and continental plates causes the developement of the continental volcanoes, which are associated and concentrated near the trench. The trench is formed when the two plates collide and one of the plates dips below the other and sinks back down running into the earth's mantle, also known as subduction or subduction zone, known as the trench. Volcanoes may rise from the sea floor, which may result in a chain of volcanic islands. Because of the earth's spherical shape, trenches are curved therefore the volcanic islands chain follows the trenches curvature , which are also called as island arcs, as the Mariana islands. The Mariana Islands are located in the Pacific Ocean. Oceanic trenches typically extend 3 to 4 km below the level of the surrounding oceanic floor. The deepest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench at a depth of 10,911 m (35,798 ft) below sea level.

Chapter 1 Critical Thinking Question 2.) In Chapter 1 it was expalined that the statement "There are mermaids in the ocean" is not a valid scientific hypothesis. Can the same be said of the statement "There are no mermaids in the ocean"? Why? *"There are mermaids in the ocean" is not a valid scientific hypothesis but nor is it to be proven false. The ocean is far too large for marine biologists to conduct a search or study on. There for, even if one says mermaids do exists because of some random incident that happened to them but maybe could have been some other kind of marine creature or was seeing things at the time; still remains a cold case file until can be proven true with some sort of hard evidence.

Sea Floor Spreading

What is sea floor spreading? Sea-floor spreading is the process in which the ocean floor is extended when two plates move apart. As the plates move apart, the rocks break and form a crack between the plates. Earthquakes occur along the plate boundary. Magma rises through the cracks and seeps out onto the ocean floor like a long, thin, undersea volcano.

What are some of the major land forms that are created from plate movement? As plate movement occurs, a long chain of mountains form gradually on the ocean floor as magma piles up along the crack, which is called the oceanic ridge.

How were the Mariana Islands formed? As plate tectonics presumes; the Asian continent and the North and South American continents are moving and that the crust of the continents are composed of different material. The edge of these plates are believed to be moving in such a manner that one moves under the other and the cataclysmic forces that result push material upward to form the islands.

What evidence exists today that the plates are still moving and that the islands are ancient volcanoes? Plate tectonics has been developed to explain the observed evidence for large scale motions of the Earth's crust. This explains that the fitting together of the coasts of the continents on the opposite side of the Atlantic Ocean express geologic formations and fossils found on the opposite sides. A geologically active mid-ocean ridge running along the central Atlantic between the opposite coasts, where as the bottom sediments get thicker and the farther one travels from the ridge, and the rocks on the sea floor on one side of the ridge show magnetic bands that are mirror images of rocks found on the opposite side of the ridge.

What is an atoll? An atoll is an island of coral that encircles a lagoon partially or completely. There are different types of reefs that make up the components of an atoll. A fringing coral reef surrounds a volcanic island in the tropical sea and will grow upwards as the island subsides, becoming an "almost atoll" (barrier reef island). The fringing reef becomes a barrier reef for the reason that the outer part of the reef maintains itself near sea level through biotic growth, while the inner part of the reef falls behind, becoming a lagoon because conditions are less favorable for the corals and calcareous algae responsible for most reef growth. Subsidence then carries the old volcano below the ocean surface, but the barrier reef remains. At this point, the island has become an atoll.

Why are atolls mainly found on the Pacific? Atolls are only found in warm tropical waters, which are the main cause of growth of the tropical marine organisms. The volcanic islands are located beyond the warm water temperature, which contain reef building organisms that become seamounts as they subside and are eroded away at the surface. The islands are located where the ocean water temperatures are sufficiently warm for upward reef growth to keep pace with the rate of subsidence.