Hydrosphere Contents

5. Aquatic Habitats

Conclusion

There are a wide range of aquatic habitats. Coral reefs are the rainforest of the sea, and provide a resource base for many fish which are in turn an input to the human food chain. They are under threat from both natural events and human activities. Freshwater wetlands account for most of the designated conservation areas. Freshwater rivers and lakes suffer pollution threats. Marine fisheries are under threat from over-exploitation.

Questions and answers

1.Why are coral reefs important?

question 1 answers

2.What acts as the natural control of coral reef growth?

question 2 answers

3.In which ways are coral commercially exploited?

question 3 answers

4. Give an example of a measure which is in place to help reduce human threats to coral reefs?

question 4 answers

5. What are the three categories of freshwater habitats?

question 5 answers

6. What are the three typical characteristics of wetlands?

question 6 answers

7.Which two chemicals can cause eutrophication?

question 7 answers

8. Phosphate is the limiting nutrient for plant growth in freshwater lakes; what is the significance of this with regards to the health of the lake?

question 8 answers

9.How does the Freshwater Indicator Indexing system determine water quality?

question 9 answers

10.Is fishing currently sustainable?

question 10 answers

11.How can incidental bycatch be eliminated in fishing practices?

question 11 answers

12.Why is the ocean bottom environment unique?

question 12 answers

13.How can the impacts of human activities on the marine environment be successfully mitigated?

question 13 answers

Question 1 answer

Coral reefs are sometimes described as the rainforests of the sea, and are of great economic and social value. Algae and plants grow on the reefs providing an important resource base for a wide range of fisheries. Reefs also protect the coastline from storm damage, and act against erosion.

Question 2 answer

Hurricanes, tropical storms and El Niño can reduce the coral reef to a pile of rubble, after which the coral can regenerate more densely. Corals are also affected by disease, and are voraciously predated by the Crown of Thorns starfish, both of which can destroy a reef in a matter of weeks.

Question 3 answer

Corals and shells are collected to sell as souvenirs or to make into jewellery. Coral can also be mined and used to build houses and roads. Millions of people visit, and inadvertently destroy, the coral reefs each year. Snorkellers and divers may kill polyps by touching and walking on coral colonies. Anchors and ship groundings can also destroy large areas of reef.

Question 4 answer

Acting as an underwater nature reserve, marine protected areas (MPAs) have become an increasingly important reef management strategy, helping to monitor reef biodiversity, promoting responsible fishery management and regulating potentially damaging activities such as coastal development, shipping and commercial marine tourism.

Question 5 answer

Wetlands, running waters and standing waters

Question 6 answer

The typical characteristics of a wetland are the presence of a very high water table, anaerobic soil conditions and a high peat content.

Question 7 answer

Nitrates and phosphates, often found in agricultural effluents

Question 8 answer

Phosphate is the limiting nutrient for plant growth in freshwater lakes. If it is present in large concentrations, the growth of plants will be unlimited. Increased plant growth can lead to the deoxygenation of the lake water which can negatively impact other species which depend on the availability of oxygen.

Question 9 answer

Studying the micro-organisms living in water can help monitor pollution levels in freshwater. If the water quality is high, organisms which are sensitive to, and cannot tolerate a certain threshold of pollution, will be present. However, if the pollution level is high, these organisms will not be present, whilst the relative number of pollution tolerant micro-organisms will be high. Freshwater indicator species are a useful tool in ascertaining the overall state of a stretch of river or stream.

Question 10 answer

The United Nations Food and Agriculture Organisation estimates that almost 80% of the world's major fisheries are fully exploited, over-exploited, or depleted. The aim of fisheries is to maximise their yields in order to increase their profits. However, this may often be to the detriment of the long-term sustainability of fish stocks. Management plans need to be implemented, based on sound scientific and conservation principles, if fish stocks are to remain healthy and commercial fishing operations to remain profitable.

Question 11 answer

By imposing selective fishing regulations on fishing companies and communities, and developing selective fishing technologies to prevent the capture of seabirds and mammals in the nets. Using fishing nets with larger sized netting can reduce the number of small immature fish caught as well.

Question 12 answer

The ocean bottom environment supports a unique ecology, which in the absence of sunlight, relies on hydrogen sulphide. Without sunlight, they survive through chemosynthesis rather than photosynthesis, by utilising the hydrogen sulphide and carbon dioxide. The ocean bottom has many important mineral reserves, including manganese oxide nodules, magnesium and sulphide deposits. Mining of

Question 13 answer

When a mitigation measure if enforced on a company which has developed a coastal areas, it requires the developers to purchase an area of a similar environmental value to that which has been destroyed, and arrange for it to be maintained in its natural state. Mitigation ensures that certain species and habitats are conserved. As it is the developers who must pay for the purchase and maintenance of the land, mitigation encouragers developers not to over develop an area.