Question

1. Define estuary, coastal wetland, salt marshes, intertidal zone, coastal zone barrier islands
2. List the problems with rapid human population decline
3. What are the major processes that can affect Natural Selection?
4. What is the difference between (GPP) and (NPP)?

Answer 1

Define estuary

An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea.

Estuaries form a transition zone between river environments and maritime environments known as ecotone. Estuaries are subject both to marine influences—such as tides, waves, and the influx of saline water—and to riverine influences—such as flows of fresh water and sediment. The mixing of seawater and fresh water provide high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world.

coastal wetlands

Coastal wetlands include saltwater and freshwater wetlands located within coastal watersheds — specifically USGS 8-digit hydrologic unit watersheds which drain into the Atlantic Ocean, Pacific Ocean, or Gulf of Mexico.

Wetland types found in coastal watersheds include salt marshes, bottom land hardwood swamps, fresh marshes, mangrove swamps, and shrubby depressions known in the southeast United States as “pocosins.” Coastal wetlands cover about 40 million acres and make up 38 percent of the total wetland acreage in the conterminous United States. 81 percent of coastal wetlands in the conterminous United States are located in the southeast.

(Conterminous-sharing common boundary)

Salt marshes

Salt marshes are coastal wetlands that are flooded and drained by salt water brought in by the tides. They are marshy because the soil may be composed of deep mud and peat. Peat is made of decomposing plant matter that is often several feet thick. Peat is waterlogged, root-filled, and very spongy. Because salt marshes are frequently submerged by the tides and contain a lot of decomposing plant material, oxygen levels in the peat can be extremely low—a condition called hypoxia. Hypoxia is caused by the growth of bacteria which produce the sulfurous rotten-egg smell that is often associated with marshes and mud flats.

Salt marshes occur worldwide, particularly in middle to high latitudes. Thriving along protected shorelines, they are a common habitat in estuaries. In the U.S., salt marshes can be found on every coast. Approximately half of the nation's salt marshes are located along the Gulf Coast.

Intertidal zone

The intertidal zone, also known as the foreshore or seashore , is the area that is above water level at low tide and underwater at high tide (in other words, the area within the tidal range). This area can include several types of habitats with various species of life, such as starfish, sea urchines, and many species of coral.Sometimes it is referred to as the littoral zone, although that can be defined as a wider region.

Coastal zone

The coast, also known as the coastline or seashore, is the area where land meets the sea or ocean,or a line that forms the boundary between the land and the ocean or a lake.A precise line that can be called a coastline cannot be determined due to the coastline paradox.

Barrier island

Barrier islands are coastal landforms and a type of dune system that are exceptionally flat or lumpy areas of sand that form by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of anything from a few islands to more than a dozen. They are subject to change during storms and other action, but absorb energy and protect the coastlines and create areas of protected waters where wetlands may flourish.

2.Problems of rapid human population decline.

When young people move to bigger towns and cities, the average age of the population in the place they leave behind automatically goes up. A community with a higher proportion of older inhabitants may be less attractive to businesses, which may additionally have difficulty finding suitable staff locally. Other effects of population decline include:

• fewer schools, due to there being fewer children;
• a drop in house prices because more homes are unoccupied;
• fewer new homes being built;
• less demand for rented accommodation;
• fewer care facilities;
• less turnover for shopkeepers and businesses;
• fewer sports facilities;
• fewer people going to the theatre, cinema or concerts, so these facilities are eventually cut back;
• fewer people travelling by public transport, which thus costlier to run;
• local residents have to travel further to reach the facilities they want.

3.Processes that affect natural selection

4.Difference between GPP and NPP