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Marine Biology 5
Marine Biology Coral Reefs
| Question | Answer |
|---|---|
| What are the mechanisms that generate and maintain the diversity of organisms? | Symbiosis, Interspecific competition, Predation, Allelopathy, Sedimentation |
| What is the importance of preserving these life forms? | Because of their prevalence, ease of collection, and ability to biosynthesize a variety of natural products, sponges have become a dominant source of natural products. |
| Interspecific competition | Like in stony corals vs soft corals--examination shows that one is digesting the other. |
| Predation | כוכב הקוצים |
| Allelopathy | |
| Sedimentation | |
| Bioerosion, grazing and boring organisms | |
| Coral Diseases | Like BBD--black band disease, tumorous skeletal growths, |
| Black Band Disease | Filamentous cyanobacterium causes the black band bordering the healthy tissue. |
| Coral Bleaching | Under temperature stress the corals begin to reject their beneficial zooxanthellae with which the share a symbiotic relationship |
| Coral Massacre in the reef flat at the coral nature reserve in Eilat 1970 | Unpredictable extreme low tide during midday exposed corals for 4 days to high irradiance causing massive mortality of about 90% of the reef flats |
| Midday low tides | Hypothesis: unpredictable midday low tides act as diversifying forces by preventing monopolization of the reef flat by single or few competitively superior species. |
| Connell's intermediate disturbance hypothesis | |
| Oil pollution in Eilat | Chronic oil spills (2-3 every month) occured in the vicinity of the coral nature reserve of eilat during 1970-79 |
| Aftermath of oil pollution | volunteers tried to cover it with hay. Its effects on the S. postillata were documented. The polluted reefs had higher mortality, very low/absence of recruitment, Fewer planulae per coral head |
| Crude Oil effects on S. pistillata | Lower number of colonies in reproduction (histological studies), decrease in the number of ovaries per polyp, lower life expectancy of planulae in increasing concentrations of oil, also premature planulae shedding. |
| Brooding | Habit of species that protect their young. |
| Result of temporal reproductive isolation of eilat coral | Hypothesis: it generates high diversity by decreasing interspecific competition. (no comp over substrate, more successful species. |
| Human polution to the coral reefs in Eilat | Until 1993 the phosphate terminal in Eilat chronically polluted the reef and technological renovations have solved the problem. |
| Direct human damage to coral reefs | Tourist industry--breakage of corals by divers. Also the 2.5 m^3 million/year sewage that had been flowing in--in 1995 they built a sewage treatment plant. |
| Fish Farming effects coral reefs | The fish cages are packed with fish. Excess food and waste provide too much nutrient content for the environment |
| Effects of fish cages-1 | Particles of organic materials sink from the fish cages to the substrate and create a thick layer of anoxic sediment rich with hydrogen sulfide and covered by microbial mats. |
| Effects of fish cages-2 | Nutrient enrichment sets up a chain reaction that stimulates phytoplankton blooms; the excess phytoplankton stimulates zooplankton production and these are eaten by fish where excess nutrients are distributed and waste products are deposited on the reefs. |
| Effects of fish cages in Eilat | Between 1996-2007 cultured fish were fed by 4200 tons/year of fish pellets resulting in the eutrophication of the water column by 300 tons of nitrogen and 50 tons of phosphate annually. |
| Vertical Mixing | During the winter cold surface water sinks pumping the nutrient rich waters to the surface. This process results in algal blooms and competitive exclusion of stony corals. |
| Algal Bloom | |
| Anoxic | Refers to waters that are completely depleted of oxygen, usually due to depleted water exchange. |
| Eutrophication and its effects on corals | It reduces survivorship and settlement capacity of planulae. It has severe adverse effects on juvenile corals at all stages and it stimulates bio eroding activities of organisms. Annual introduction of 350 tons of nutrients that are foreign to the waters. |
| Other problems with the fish cages | There are a point source for the dispersal of infections, parasites and pathogens. It also includes the introduction of non-indigenous species. They use antibiotics, antifouling paints, TBT concentrations are then elevated and they use growth hormones. |
| Mycobacterium | A bacterium of the tuberculosis cluster causing fish infection which is lethal. It is absolutely absent in wild fish populations in the 70's and 80's but since the 90's it has effected 40% of the population. |
| Eutrophication effects on the growth rate of the coral reefs of Eilat | Measurements indicate an increase of 75% in the concentration of nutrients dissolved in the deep water column. An increase in the deep pool of dissolved inorganic nitrogen, in the potential growth of macro algae and organic sediment content. |
| Coral reefs of Eilat today | Population explosions of a predatory snail, high mortality rate of branched corals, enhanced eutrophication encourages proliferation of sea weeds (mass mortality to stony corals) |
| How many people are required to produce sewage which is equivalent to the amount of nutrients released by the fish farms? | Sewage produced by a city of 70,000 people |
| Seasonal water flow in the Gulf of Aquaba | In the summer its southward from the northern shore of the gulf towards the MBL |
| Reproductive activity among marine life in the Gulf of Akaba | The summer season is also the season of the most intensive reproductive activity. Small increases in concentrations of N and P have severe effects on it for corals. |
| Conclusion about fish cages | They increase P and N concentrations which can be severely detrimental to coral reproductive activity and they produce 10 times as much as any other polluting source. |
Created by:
YaelNoa
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