Decrease In Crayweed Population And The Process Of Regenerating These Population

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Abstract: The crayweed around the Sydney coastal area has experienced significant decline in recent decades. It has been suggested this was due to the increased human activity in the 1970s to 80s. More recent projects have enabled the reintroduction of crayweed into its previous range. Conclusive evidence of the causes of decline, and the success of the reintroduction projects can now be established. It has been hypothesized that the decline of crayweed due to rapid population increase in the period 1970-89 in the greater Sydney area. This has led to increased pollution and runoff into the ocean. Methodology included historical research and field work. Project results indicate the crayweed has increased of late in the Sydney coastal area. This may be due to increase in water quality and better coastal management.

Introduction: Seaweed or macroalgae refers to several species of macroscopic, multicellular and marine algae. Seaweeds in the sea have neither leaf, stem or root. However they have other structure whose function is similar to land plants. They substitute blade, stipe and holdfast into leaf, stem and root. The blade also has large surface area to absorb sunlight but some seaweeds only have one blade, which may be divided while other species have a number of blades. The stipe supports the rest of the seaweed plant. The structure of it is much different among each seaweeds but holdfasts are needed to resist water flow. Therefore it is made up of many fingerlike projections called haptera. However,these seaweeds are in decline. A global study found that 38% of the worlds kelp forests have declined over the past 50 years. The main cause of the decrease is said to be sea warming. The environmental stress may lead to a general increase of diseases in marine habitats. In Sydney, some people restore the forests of the essential species by creating patches of transplanted crayweed onto a reef.

Literacy review: Sea Warming: Sea Warming is a big threat to the population of algae in the world's oceans. Most notably in the algal forests of Eastern Australia and Tasmania. The most heavily affected being the algal forests in Tasmania which has had 95% of its mass destroyed. This destruction has been caused by rapid warming of sea water. Rising ocean temperatures have caused the death of several species of kelp, such as Ecklonia radiata native to western Australia and Saccharina latissima or sugar kelp from southern Norway. In the late 1990s, sugar kelp died because of rising ocean temperatures and could not grow back because of turf algae which took its place. In western Europe Laminaria digitata is at risk of dying out completely, this is because of the Atlantic ocean around France, Denmark and Southern England heating up. Researches have predicted this will happen by the first half of the 21st century.

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Methodology: Initial observations were made with the naked eye in a number of locations. This involved trips to the site locations, both on foot, and by diving on the reefs. The dives were used to observe the sediment and growth of the crayweed. Photographic evidence suggests that the reefs have increased in recent years. Methodology for testing water quality included accessing the crayweed project's achieve to find test results from the 1980s. A further method consisted of collecting health samples from the sea floor. These included more recent trends dating from the period 2016-18, and from sediment from that was deposited in the years 1970-1990, obtained during excavation. Finally, analysis of graphs was undertaken, with several samples identified.

Result: In the observation, I found many vegetation’s life activity. I could found many small creatures but a number of them eat seaweeds. Especially, sea urchins were one of the largest animals we found so It seemed to need more nutrients than other small creatures. From the research, I found the two cause of the decline seaweeds. The main cause is the kelp’s dead by sea warming. In Australia, some species are shifted north and south. The population of the crayweed decline near the Sydney. From the figure 1, we can find that most of the seaweeds shifted southward in the east coast and shifted northward in the west coast. On the other place, the kelps can’t grow back by the turf algaes took the place of the kelps. However, the people plant the sea weed with the patch not to travel somewhere or be taken their place. The another reason is sea urchin. The sea urchins usually eat seaweeds. If only that, it doesn’t affect to the ecosystem but the number of the long-spine sea urchin is bombed in 1980s. In addition, if they form the urchin barrens, any other vegetation cannot grow up. Therefore, it became serious issue. From the figure 2, the population of the kelps were decreased rapidly. Some researchers came up with the way to prevent the increase sea urchin but it wasn’t completely successful.

Discussion: In the research, I could get the good results about my inquiry question. My question is to research about the cause of decrease seaweed and the way of regeneration of them. First, l went to the excursion and survey many creatures in the sea. In this time, I saw the many seaweeds and their life activities. Especially, seeing sea urchin became one of the element to accept the content of the article on the Internet. The size of sea urchin was bigger than I expected so I understand that the increase the sea urchins influence other ecosystem. The excursion was gave me the benefit for the assessment task. Second, I research on the Internet. I studied with the support of the teachers and the friends. I found the article from the web site in the UNSW. It described about the recent trend in the seaweeds moving. I chose this article because if I want to know Explained the reason of the decline, the trend of them is essential information. However, it wasn’t enough so I referenced another article. Another one was about the sea urchin. That is a main cause of the decline seaweeds in the world. I could utilize the information from the excursion on this research. From whole research, we cannot get the result I want because the way to fix the unstable ecosystem haven’t found yet.

However, It means that there are no way to fix easily. How it affected the ecosystem: Sea warm is also causes bombed long-spine sea urchin, which cannot alive in the temperatures lower than 53 degrees Fahrenheit. When sea warm is happened, they travel southward and form vast urchin barrens. Lobsters, which eat urchins are fished by human for decade, so the number of urchin bombed. In addition, they are annihilating the seafloor vegetation while forming the urchin barren. Therefore, the seaweeds are decline rapidly and species which eat seaweeds are died. The decline of the seaweeds becomes serious issue in the world.

What has been done to fix it: In UNSW, the people attach the patch on the big rocks and translocation the seaweeds on it. This way can keep seaweed on same place but if the sea urchins come and eat seaweeds, we can’t protect seaweeds from them. In Tasmania, some researchers tried to increase the localized population of predatory rock lobsters. They called out fishers and tightly restricted lobsters harvest to increase their numbers. However, it was only moderately successful. We still don’t found the way of suppress the decline of the seaweeds. What else can be done: We can fish the sea urchins to protect the seaweeds. However, the increase the sea urchin is caused by human. If we fish the sea urchin, the number of the sea urchin is also decrease and lose the balance of the ecosystem again. We should respect the nature in the sea so we should farm the kelp and lobster, and make steady effort to recover the ecosystem.

Conclusion: The main cause of decline seaweeds is sea warming and increase the sea urchin. Some people have already started to regenerate the seaweeds but the way to prevent the increase the sea urchin is haven’t found yet. When the sea urchins form the urchin barrens, we can’t prevent them now. If we want to fix the ecosystem, we have to make steady small effort like the crayweed project in the UNSW. Also, we don’t think about decreasing other species to get balance of the ecosystem. Therefore, we should consider this problem seriously and get answer as soon as possible.

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