## Contents

SECTION 3 Aquatic Ecosystems E ♦ 79

James R. Fisher/DRK Photo

### Saltwater Ecosystems

About 95 percent of the water on the surface of Earth contains high concentrations of various salts. The amount of dissolved salts in water is called salinity. The average ocean salinity is about 35 g of salts per 1,000 g of water. Saltwater ecosystems include oceans, seas, a few inland lakes such as the Great Salt Lake in Utah, coastal inlets, and estuaries.

Applying Math

### Convert Units

TEMPERATURE Organisms that live around hydrothermal vents in the ocean deal with temperatures that range from 1.7°C to 371°C. You have probably seen temperatures measured in degrees Celsius (°C) and degrees Fahrenheit (°F). Which one are you familiar with? If you know the temperature in one system, you can convert it to the other.

You have a Fahrenheit thermometer and measure the water temperature of a pond at 59°F. What is that temperature in degrees Celsius?

Solution

Q This is what you know:

Q This is what you need to find out:

Q This is the procedure you need to use:

Check your answer:

Practice Problems water temperature in degrees Fahrenheit = 59°F The water temperature in degrees Celsius.

• Solve the equation for degrees Celsius: (°C X 1.8) + 32 = °F

• Substitute the known value: °C = (59°F - 32)/1.8 = 15°C

Substitute the Celsius temperature back into the original equation. You should get 59.

1. The thermometer outside your classroom reads 78°F. What is the temperature in degrees Celsius?

2. If lake water was 12°C in October and 23°C in May, what is the difference in degrees Fahrenheit?

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