Question

1. an estuary is best defined as:

a) a completely enclosed marine environment
b) a semi - enclosed area where freshwater and seawater meet and mix
c) a deep ocean trench
d) a mountain river system

1. which of the following is not a typical function of estuaries?

a) providing spawning grounds for marine organisms
b) filtering pollutants from water
c) generating electricity
d) serving as a buffer during storms

1. estuaries formed when sea levels rose at the end of the last ice age are called:

a) tectonic estuaries
b) fjords
c) drowned river valleys
d) bar - built estuaries

1. the salt wedge phenomenon occurs because:

a) freshwater is lighter and flows on top
b) seawater is denser and flows along the bottom
c) tides push water randomly
d) rivers always mix salt and freshwater evenly

1. which characteristic makes estuaries highly productive ecosystems?

a) constant salinity
b) lack of predators
c) high nutrient input from rivers and tides
d) stable temperature

1. anadromous fish are unique because they:

a) live exclusively in saltwater
b) migrate from freshwater to spawn in the sea
c) migrate from the sea to spawn in freshwater
d) never leave their original habitat

1. in salt marshes, plant zonation is primarily determined by:

a) soil type only
b) temperature variations
c) effects of flooding, tides, and salinity
d) predator distribution

Explanation:

1. An estuary is a semi - enclosed area where freshwater (from rivers) and seawater meet and mix.
2. Estuaries do not typically generate electricity. They provide spawning grounds, filter pollutants, and act as storm buffers.
3. When sea levels rose at the end of the last ice - age, drowned river valleys were formed as estuaries.
4. The salt wedge phenomenon occurs because seawater is denser and flows along the bottom while freshwater is lighter and flows on top.
5. Estuaries are highly productive ecosystems due to the high nutrient input from rivers and tides.
6. Anadromous fish migrate from the sea to spawn in freshwater.
7. In salt marshes, plant zonation is primarily determined by the effects of flooding, tides, and salinity.

Answer:

1. B. A semi - enclosed area where freshwater and seawater meet and mix
2. C. Generating electricity
3. C. Drowned river valleys
4. B. Seawater is denser and flows along the bottom
5. C. High nutrient input from rivers and tides
6. C. Migrate from the sea to spawn in freshwater
7. C. Effects of flooding, tides, and salinity