Marine science please help!!!?

[rolfe16]

Coral reefs are usually found near the equator between the Tropic of Cancer and the Tropic of Capricorn. Which of the following best describes why this is an ideal location for coral?
A)warm water temperatures
B)wave action
C)longer rainy season
D)changes in salinity

Certain corals have been found in extremely deep water. These coral lack the zooxanthellae that are found in tropical coral reefs because zooxanthellae require sunlight to go through photosynthesis and there is no sunlight available at these depths. These deepwater coral often are built upwards instead of across the bottom. Why do the polyps build the coral this way?
A)The pressure of the deep water is too great to build outwards.
B)They grow to avoid predators.
C)They are filter feeders.
D)The temperature of the water keeps them from building outwards

Coral reefs face many threats. Destructive fishing is an example of a ________________ threat.

A)chemical
B)agricultural
C)natural
D)man-made

Which of the following is an example of a mollusk in class Gastropoda?
A)nautilus
B)clam
C)squid
D)conch

Which of the following does NOT describe an estuary?

A)partly enclosed area of brackish water not affected by high and low tides
B)partly enclosed area with brackish water strongly affected by high and low tides
C)home to large variety of flora and fauna
D)highly productive and polluted area

Which of the following could explain a decrease in the salinity of water in an estuary?

A)High tide moves saltwater in to an estuary.
B)High tide moves freshwater in to an estuary.
C)Low tide moves saltwater out of an estuary.
D)Low tide moves freshwater out of an estuary.


I've gotten every answer except these, and I'm completely stuck! If someone could answer like one or 2 it would make my life so much easier, since I'd have enough points to bomb the rest of these above questions.(I KNOW I got the others right)

[philibert63]

Coral reefs are found near the equator because of warmer water.

Destructive fishing is a man-made threat.

Gastropoda are the snails; a conch is a snail.

In the question on the estuary, since a and b are opposite, you know one of them must be the correct answer - estuary are affected by the tide.

Since the ocean (the source of the tides) are salt water, low tide moves saltwater out of an estuary. Strictly speaking, since at low tide, with the salt water gone, the freshwater can move out too, d could also be considered a correct answer.