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mar bio exam 5
| Question | Answer |
|---|---|
| The continental shelf is | the submerged edge of a continental plate. |
| The continental shelf extends from | the low tide line to an area known as the shelf break. |
| The slope of the continental shelf is normally more gradual, whereas, the slope past the shelf break is | normally very steep. |
| Estuaries are much more well developed in areas of the world where | the continental shelf has a gradual slope and is very wide. |
| The depth of water at the shelf break varies greatly with an average depth of around | 490 feet. |
| The width of the continental shelf varies greatly from | 0.6 miles to 470 miles with an average of 48 miles. |
| A major portion of the fisheries global catch is caught over the | continental shelf. |
| A wide variety of organisms can be found on/in the continental shelf. Some of the most common includes | sponges, cnidarians, worms, molluscs, fish and echinoderms. |
| Temperature of the water over the continental shelf varies much more than | the water in the deep sea (but less than in an estuary). |
| The temperature in a continental shelf fluctuates more because | the water is shallower than in the deep sea and because waves and currents keep the water circulating |
| Water turbulence created by waves and currents keep the water column well mixed.This affects not only the temperature of the water, but also affects | the nutrients available in the water. |
| Nutrients come from many sources, including: | -Autotrophs -Decaying marine organic matter -Nutrients delivered from estuaries and terrestrial ecosystems via rivers |
| Soft-bottomed benthic- | -Dominant bottom type on the continental shelf. -There are more species present in this area than in the adjoining intertidal, but the distribution is often patchy |
| Sessile types are rare int he Soft-bottom benthic due to lack of | “hard substrate” for attachment (remember, limiting resources?) |
| Many tube-builders can assist with the stability of the | soft bottom habitat |
| Many soft-bottom benthic species are | deposit feeders (directly getting nutrients from the soft bottomed material) -Many other species are suspension feeders and filter nutrients directly from the water |
| Bioturbators (organisms that disturb bottom sediments) constantly “churn” the bottom This churning helps to | oxygenate benthic soils |
| Bioturbators can include | worms, mollucs, fish and even whales |
| Skates and stringrays as well as sperm whales are well known for their activity as | bioturbators |
| Seagrass Beds | -They are best developed in sheltered, shallow waters with good water clarity -There are over 50 known species |
| Due to narrow tolerances, species of seagrass bed normally prefer either | cool waters OR tropical/subtropical waters, but not both |
| Seagrasses are often found in | combination with algal species |
| The density of individual seagrass plants tend to be | very thick (high biomass) |
| Thalassia (turtle grass): | -is a common seagrass in tropical and subtropical areas -It is named turtle grass because it is often directly consumed by green sea turtles |
| Zostera or eelgrass prefers | cooler, temperate waters It is mainly found in the Pacific and the North Atlantic |
| Hard-bottomed subtidal- | -Less common -Often, it is the result of a submerged rocky shoreline |
| Rock formations attract a wide variety of organisms including | many sessile types that cannot survive in soft bottomed communities |
| Oyster reefs, worm tubes and calcareous algae can all serve as | hard-bottomed subtidal communities |
| One of the most important features of the rocky hard-bottomed community is | the hiding places it provides for prey and predators alike |
| Kelp community- | Kelps are brown algae that are restricted to cold waters in distribution |
| In addition to requiring cold water, kelps are | very nutrient-needy |
| Laminaria is a species of kelp common in | the North Atlantic, North Pacific and the Asiatic coast of the Pacific - large primary producers |
| Macrocystis: -is a large species of kelp that can grow heights of over 100 feet -forms thick forests that serve as | a MAJOR ocean ecosystem in the areas where it is found |
| Sea urchins are by far the largest direct consumer of | kelp |
| The soft body of the coral (polyp) is enclosed in | a hard shell of calcium carbonate “skeleton” created by the coral (technically called theca). |
| Hermatypic corals- | -Reef builders -Normally contain zooxanthellae, symbiotic photosynthetic dinoflagellates -Restricted in distribution by water temperature and water quality |
| Ahermatypic corals- | -Do not build reefs -May not contain zooxanthellae -Not restricted by water temperature and water quality |
| Corals are groups of | polyps inter-connected by thin layers of tissue |
| Grouped coral polyps share a | nervous system and digestive connection – this is due to the fact that the entire colony came from one original polyp. |
| Each coral polyp continues to lay down new CaCO3 beneath the polyp body so the entire coral colony continues to | grow upward |
| The zooxanthellae housed inside the coral produce | organic matter through photosynthesis |
| If zooxanthellae are supplied with enough light, they can | feed the coral completely |
| Coral possess | nematocysts to sting potential prey that come within reach of the tentacles |
| Coral can also feed using extensions of the gut wall called | mesenterial filaments These filaments secrete digestive enzymes. |
| The coral can extend the mesenterial filaments with its enzymes allowing the coral to | feed and digest food outside the body |
| Conditions Required for Reef Growth | -Hard Substrate -Light Optimal -Narrow temperature range -Narrow salinity range -Low sediment load in water -Low pollution -Narrow range of pH |
| Corals reproduce | both sexually and asexually |
| Asexual reproduction in corals allows for | the growth of buds from a single polyp |
| Sexual reproduction in coral results in | the creation of a planula larvae that is able to ride on the water currents to a new environment |
| Light must be able to penetrate the water to the depth of a coral to allow | the symbiotic zooxanthellae to photosynthesize |
| Corals are mostly found on | continental shelves, near islands or on seamounts due to this light/depth dependency |
| Reef building (hermatypic) corals tolerate | a narrow temperature range compared with most marine organisms |
| Corals can only reproduce and grow if water temperatures are | over 68 degrees F |
| water temperatures above 86 degrees (or higher in some species) causes | coral stress. This can lead to “bleaching,” an expulsion of zooxanthellae from the coral polyp. |
| Poor water quality, increased sediment in water column, wave stress or disease can also | cause bleaching |
| Widespread bleaching often occurs as a result of events such as | El Nino (increased water temps) and hurricanes |
| Corals normally do not exist near areas where rivers deliver large amounts of freshwater to the marine environment because of | salinity requirement (35ppt) |
| Corals do not normally grow in areas where wave action is high This is due to the fact that heavy wave action results in | the suspension of sediments in the water column |
| Taller, more branching coral tend to be more common in | shallower areas of the reef due to intense competition for space and light |
| Flatter coral forms tend to be more common in | deeper areas of the reef; this probably assists with capturing all possible light available. |
| Scleractinian corals are | the main reef builders. Produce a calcerous skeleton. Most have zoooxanthellae. |
| Soft corals | non reef builders. - Most have zooxanthellae , calerous sksleton. |
| Gorgonians | sea fans and sea whips. Skeleton of protein. |
| Fringing Reefs | -Simplest and most common form of reefs -tropical waters -These reefs develop as narrow strips along the shore -consist of an inner reef flat and an outer reef slope |
| Growth of fringing reefs are normally fairly high on | the reef slope and especially at the reef crest |
| Coral growth is slower on the reef flat due to | runoff from land which includes sediment, freshwater and pollution |
| Barrier Reefs | grow along the shore or may be farther from shore. They are different from fringing reefs by the presence of a deep lagoon between the shore and the reef |
| Belize barrier reef is | the 2nd largest barrier reef in the world |
| Waves often wash sediment onto the back reef slope or reef flat which causes | reduced coral growth in this area |
| Enough sediment may accrue to form small islands on the reef. These islands are called | keys in the US or cays elsewhere |
| Coral growth is normally the highest at the | reef crest or just below the crest on the fore-reef slope |
| The Great Barrier Reef is considered | the largest reef structure in the world with regards to total coral area. -The length of the reef systems exceeds 1200 miles |
| Atolls | a circular reef structure surrounding a central lagoon |
| Sand cayes may be a part of the | atoll structure |
| Atolls form when | a volcanic island is formed -The coral begins as a fringing reef around the newly formed island -Eventually, the island disappears below the water’s surface, leaving only the outer band of coral surrounding a lagoon |
| Atolls possess a reef flat and | inner and outer reef slopes |
| The two largest atolls are in | the Maldives (Indian Ocean) and the Marshall Islands (Pacific) |
| Patch reefs | relatively small, isolated coral reefs found between the shore and barrier reef |
| Cyanobacteria present on the reef are able to fix nitrogen which is then available to | other reef inhabitants who feed on the cyanobacteria |
| Many coral reef inhabitants can deter predation by | producing toxic or foul tasting chemicals – this is common in soft corals and sponges |
| Coralline algae as well as other organisms grow in an encrusting form that is | difficult to feed upon (tissue layer is VERY thin) |
| Corals may feed directly or | sting one another if they contact each other |
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