Describe a basic aquaculture operation. (worth 2 points) 2. 3. Summarize the pro

Question

Describe a basic aquaculture operation. (worth 2 points) 2. 3. Summarize the problems that can occur in mariculture. (worth 3 points) Discuss how pollution and destruction of habitat that result from aquaculture impact marine environments. (worth 5 points) 4. Section 3: 1. Define: (each worth 1 point) a. Marine natural product 2. Identify: What problems are associated with the harvest of mangroves and corals? (worth 3 points) 3. Identify: what are the impacts of the aquarium trade on marine ecosystems? (worth 3 points) Section 4: 1. Define: (each worth 1 point) a. Methane hydrate b. Polymetallic nodules

Explanation / Answer

Q2) Describe a basic aquaculture operation----

Answer- Oyster farming is an aquaculture operation. In this the salinity and temperature of the water are controlled, to induce spawning and fertilization and to increase the speed of maturation.

In the first step it is required to condition the brood stock or parent stock because from them gametes for the larvae are obtained, To have matured oysters for spawning throughout the season, some growers prefers to keep mature oysters in a separate system where the temperature and food within the system can be manipulated. And a recirculating system usually used, a flow-through the system is preferred, because the natural diversity of phytoplankton is a better diet for conditioning the oysters.

When the farmer wants to spawn the oysters, he or she puts a batch of oysters in a tray and rapidly heat and cool the water to induce spawning. Usually a large number of oysters are taken, because it is not possible to detect externally either it is a male or female. When the oysters start to spawn they are picked up and kept in a separate containers, till they release all their gametes. Eggs and sperms then mixed together to fertilize.

After around two weeks an oyster is ready to set. They develop an “eyespot” and their muscular foot gets visible under a microscope. At this stage, the larvae are put in a system having a variety of cultch options (stones, broken shells, and grit from which an oyster bed is formed.) The best cultch is usually a full or ground up oyster shell because oysters are naturally attracted to other oyster shell for the reproduction process, once the larvae settles.

Three methods of cultivation are used they are i) The spat or seed oysters are distributed over existing oyster beds and are allowed to mature naturally. Such oysters are collected using a method called dredging. ii) Second method is spat or seed are put in racks, bags, or cages and are held above the bottom. Oysters cultivated by this method are harvested by lifting the bags or racks to the surface and removing mature oysters. iii) In the third method, the spat or seed are placed in a cultch in an artificial maturation tank, the maturation tank is fed with water specially prepared to accelerate the growth rate of the oysters, the third method though the last method production is more avoiding poaching , but is the most expensive method of oyster cultivation.

3) Summerize the problems that can occur in Mariculture---

Answer-The problems occurring in Mariculture are the environmental problems , they are i) Wastes from cage cultures, ii) Farm escapees and invasives iii) Genetic pollution and disease and parasite transfer, iiv) Habitat modification.

Besides these problems, other problems, taking place in mariculture are -Nitrogen and Phosphorus compounds from food and waste leads to blooms of phytoplankton, There gradual degradation may reduce the oxygen levels. If the algae are toxic, fishes gets killed and shellfish are contaminated.

Q4) Discuss how pollution and destruction of habitat that result from aquaculture impact marine environment.

Answer- Fishing an aquaculture practise puts impact on the marine environment, Some fishing techniques causes habitat destruction they are the Blast fishing and cyanide fishing, these are though illegal in many places, when used harm the surrounding habitat. In Blast fishing explosives are used to capture fish. In Cyanide fishing cyanide are used to make fish unconscious for fish collection. These methods are destructive because they puts great impact on the habitat where the reef fish live. Bottom trawling, is another method in which the fishing net is pulled along the sea bottom behind trawlers, by this method around 5 to 25% of an area's seabed life in a single time. Over-fishing also affects the over-exploitation of marine ecosystem. Fishing also disturbs the food web.

Damaging the habitats kills the plants and animals who are responsible for the habitat's ecological functions, survival and regeneration.  

Pollutants from urban sewerage and industrial waste in the form of hazardous, and toxic water. Enters sea by rivers, minerals due to mining also they go to sea, and interfere the development of coral polyps. These minerals and heavy metals like mercury, effects the water quality, imbalances the oxygen levels, and later settles down. Which is a breeding ground of many species of fishes. Oil spills also affects the marine life.

Oceans are the natural carbon sinks, because they absorb most of the carbon dioxide from atmosphere, this causes marine water acidic, as a result the corals and shell fish may not be able to form shells. The methane clathrate reservoirs found on the ocean floors, traps huge amounts of green- house methane. Leading to thickening of sea water by 3-14 meters.

Due to increase in chemical nutrients, eutrophication occurs, they cause plant growth and decay, this leads to depletion of oxygen, and severe reduction in water quality affecting fish and other animal population.

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