Geography answers and questions for CSEC

Three ways coral reefs are destroyed: 1. Water Pollution - Reefs are harmed when oil, fertilizer, human and animal waste are dumped in the area. This waste can also block life-giving sunlight to the reef. Floating trash can cut young coral polyps off from nutrients they need to grow into a thriving reef. 2. Global Warming - This causes significant temperature increases in waters in which corals inhabit. This rise in sea temperature creates a very stressful living environment for the coral reef. Coral Reefs respond to such stresses by ejecting necessary symbiotic Zooxanthellae (which are single celled photosynthetic organisms that provide vital nourishment to the coral). This ejection leads to a loss of pigmentation in the coral reef, this is known as coral bleaching 3. Sedimentation - Construction and mining along sea coasts can create a great deal of silt and soil run off. Particles that enter the ocean can smother coral reefs, depriving them of sunlight and nutrients. Fish are unable to feed and coral polyps are unable to grow leaving the area inhospitable to reef life. Three measures used by St. Lucia to reduce coral destruction 1. Fisheries laws- establishing marine protected areas or marine reserves (is a type of marine protected area that has legal protection against fishing or development). These marine reserves will protect marine life. 2. Monitoring – fisheries officers or marine police randomly the coastline to ensure people don’t destroy the coral reefs. 3. Zoning – dividing the coastline into multiple uses like no fishing areas, marine protected areas, recreational fishing priority. Zoning helps to manage and protect the values of marine life Why few coral reefs are found near the mouth of rivers

Corals occur in a salinity range between 32 and 40 PSU although coral reefs also thrive in exceptionally high and low salinity conditions. More important than average salinity concentrations, however, are sudden decreases in salinity due to high freshwater input by rivers or torrential rains. Decreased salinity is seen as a second factor for the disappearance of massive coral reefs in front of large river mouths.

Corals need access to sunlight (the algae living in their cells need light for photosynthesis) so the water where they grow needs to be shallow and clear. Too much sediment in the water can smother the coral polyps and too much fresh water kills them. That is why coral reefs don't grow close to the mouths of rivers.

Karst - landscape underlain by limestone that has been eroded by dissolution, producing ridges, towers, fissures, sinkholes, and other characteristic landforms. Two characteristics of limestone that make it susceptible to chemical weathering 

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Joints - Limestone is pervious so water can travel through it. Joints are cracks that are found in limestone rocks. These joints are areas where the limestone is very susceptible to chemical weathering. The gaps created by this process are called grykes. Bedding planes - Bedding planes provide pathways for the entry of water. This contributes to chemical weathering of limestone. A rock with lots of these features will weather more rapidly than a massive rock containing no bedding planes.

How Caves are formed A cave is a naturally occurring underground hollow or passage, especially one with an opening to the surface of the Earth. They are formed when s stream disappears down a sink hole and dissolves along the bedding plane.

How sink holes are formed Surface and rain water do not flow far on exposed limestone, but infiltrate rapidly into the rock and soil. Where a joint or intersection of joints has been greatly

weathered water can pass down through the limestone. A stream travelling over an impermeable rock will very quickly disappear when it has to travel over limestone. These sinkholes can be many meters deep leading down to a series of subsurface features.