Threats to ocean ecosystems are

As they flow down a mountain to flatter ground, rivers generally become

What mainly distinguishes nekton from benthos?

Which of the following statements is not correct?

Estuaries

Which of the following is a threat to coral reefs?

Estuaries are very productive ecosystems because they receive fresh nutrients from

What causes most coastal pollution in the United States?

Which organism produces most of the food in an aquatic ecosystem?

An estuary functions as a mineral trap due to

Which of the following is not an environmental function of wetlands?

In the _____ zone, the water is cool and dark.

Why doesn’t photosynthesis occur in deep ocean water?

The majority of marine organisms are found in

Coral reefs are intricately shaped rock-like structures that are formed as a result of

What are the two main types of freshwater wetlands?

A river changes with the _______________________________ and ______________________________ through which it flows.

Fish are a type of _________________________, or free-swimming, organisms.

In estuaries, fresh water and salt water mix, forming a(n) _______________________ trap.

Marshes are dominated by ____________________________ plants

Swamps are dominated by ____________________________ plants

Excessive nutrient growth in an aquatic ecosystem can be accelerated by ____________________.

Upstream, a river is usually cold and flows _________________________ through a shallow riverbed.

An estimated ____________________ percent of all coral reefs are in danger.

Barnacles are a type of _________________________, or bottom-dwelling, organisms.

Most ocean pollution can be traced to activities on __________________________.

The amount of dissolved salts in water is known as _________________________.

Mosses use _________________________ to anchor themselves to rocks near churning river headwaters.

Plankton that are microscopic plants are called ________________________________

Plankton that are microscopic animals are called ________________________________