Water saver: could a population boom cause a decline in one bay's water quality? An environmentally concerned teen finds out.

Barnegat Bay was once a sleepy body of water by the New Jersey shore (see map, right). Then, more and more people discovered the bay's natural beauty. They began settling around this estuary, where freshwater from rivers and streams meets saltwater from the sea. Since 1960, the number of year-round Barnegat Bay residents has quadrupled to 500,000. And during the summer, vacationers flock to the bay, doubling the normal population. "I've spent parts of every summer there," says 16-year-old Anastasia Roda. "It has gotten much more well known in the last 10 years."

But Barnegat Bay is more than just a vacation spot. It's rich in wildlife and serves as a nesting ground for many species of shorebirds. The bay's brackish water, which is a mixture of fresh and salt water, also supports a lot of marine life, including blue claw crabs. "They can't survive in the ocean or in the rivers," says Anastasia. When the 10th-grader from Lancaster, Pennsylvania, heard longtime bay residents say that they had noticed changes in the marine life in recent years, she was intrigued.

For example, many people have seen an increase in a jellyfish species that thrives in areas with high nutrient levels. So Anastasia wondered if the bay's water quality has changed. She suspected that the area's population boom could mean that more pollutants such as nutrient-rich lawn fertilizers, trash, and household chemicals might be seeping into the estuary.

Anastasia was concerned: If Barnegat Bay's water quality has indeed declined, then its delicate ecosystem could be at risk. So two years ago, Anastasia began a science project to test the water. She wanted to find out if an increased human population has had a negative impact on the bay's water quality.

GET READY

To stay organized, Anastasia followed the scientific method. This step-by-step process that scientists use to perform experiments is important. "It provides you with something to follow," explains Anastasia. "That way, you won't go off in a random direction." Here's how she followed the steps and turned her concerns for Barnegat Bay into an award-winning science project.

STEP ONE: INVESTIGATE

All experiments begin simply, starting with an observations. Anastasia learned about a population boom in the areas surrounding Barnegat Bay. She also heard longtime residents describe how the bay has changed over the years.

To move on to the next step of her project, the teen needed to learn what scientists look for when they test water quality. So Anastasia combed many Web sites and did background research. "I found that there are 11 indicators that are commonly used for basic analysis of water quality," she says. Two of these indicators are nitrogen and dissolved oxygen, or the amount of oxygen in the water.

STEP TWO: PREPARE

Next, Anastasia came up with a research question: Has the increased human population since 1960 around Barnegat Bay caused a decline in the bay's water quality?

Since Anastasia could not answer that question without further investigation, she first made a hypothesis, or possible explanation for a set of observations. A hypothesis must be able to stand up to a test, so she stated her hypothesis this way: The increased population around Barnegat Bay since 1960 has caused a decline in the bay's water quality.

STEP THREE: SAMPLE THIS

To find out if her hypothesis was true, Anastasia had to run an experiment. "An experiment gives you evidence," says Anastasia. "It helps you answer your question." To get reliable results, an experiment must include a carefully mapped out procedure (see p. 14), or a step-by-step plan containing clear instructions to test the effect of one or more variables (characteristics) on another.

To learn about the current water condition in Barnegat Bay, Anastasia collected water samples on a regular basis over one summer. She used water-testing equipment to determine the levels of 11 water-quality indicators. To get a better sense of how Barnegat Bay has changed over time, Anastasia consulted experts. With their help, she gathered water-quality data, or collected information, for the region from the last 40 years.

In any experiment, there are two major types of variables:

The independent variable, or the factor that you change on purpose, and the dependent variable, or the factor that responds to the change in the independent variable. In Anastasia's experiment, the independent variable was time--which reflects the corresponding population increase that occurred in Barnegat Bay every decade. Her dependent variable was the level of water-quality indicator.

STEP FOUR: FINDING ANSWERS

After studying the data, the budding scientist reached a conclusion, or a result summary.

Of the 11 water-quality indicators, four worsened, four improved, and three stayed the same. "When I first looked at my data, I rejected my hypothesis," Anastasia says. But she changed her mind after examining the indicators that had gotton worse. "I realized that the ones that had worsened were actually the most important ones," she says.

Anastasia found an increase in the level of nitrate-nitrogen, a nutrient that comes front plant fertilizers. She also discovered that the level of dissolved oxygen had decreased every decade since the 1970s. Because most organisms need oxygen to survive, this decline spells danger for marine life. "Low dissolved oxygen levels could cause stress to, or even kill, fish populations," says Anastasia.

SPREAD THE WORD

Anastasia entered her science project in numerous science fairs. Her work impressed the judges, and she won several top prizes. The teen was even selected as a national finalist in the Discovery Channel Young Scientist Challenge 2004.

But getting awards is not enough for Anastasia. "When I learned about all the things that could harm water quality, I wanted to tell people about it," she says. She applied for and received grant money front the Environmental Protection Agency's National Estuary Program to create and distribute a pamphlet to educate visitors on how to protect Barnegat Bay.

Nuts & Bolts

SCIENTIFIC-METHOD CHECKLIST

* Base your idea for an experiment on an observation.

* State your purpose. Usually, the purpose of an experiment is stated in the form of a research question: What is the effect of [your independent variable] on [your dependent variable]?

* Perform background research to find out what is already known about your topic.

* State your hypothesis, a possible answer to a research question.

* Design a detailed procedure, or list of steps (see p. 14).

* Carry out your experiment and collect data.

* Record your results. In many cases you can present your results in charts, pictures, or graphs (see p. 18).

* Draw a conclusion from your results. Did your hypothesis prove true?

SCIENTIFIC METHOD: WORDS TO KNOW

VARIABLES: Characteristics in an experiment that change or could be changed.

INDEPENDENT VARIABLE: Factor that you change on purpose; also called manipulated variable.

DEPENDENT VARIABLE: Factor that responds to a change in the independent variable; also called responding variable.

HYPOTHESIS: Possible explanation for a set of observations or an answer to a scientific question; must be testable.

CONSTANTS: Characteristics in an experiment that are kept unchanged in all trials.

CONTROL: Standard to which you will compare your results.

TRIALS: Number of times an experiment is repeated for each level, or value, of the independent variable. The more trials, the more reliable your results.