Practice designing an experiment

Practice stating and testing a scientific hypothesis

Practice communication and presentation skills

Increased understanding of estuaries in general and Puget Sound in particular

Estuaries are embayments where rivers empty into the ocean. In these inlets, river runoff, tidal fluctuation, channel configuration, and irregular bathymetry conspire to create some of the most complex circulation patterns in the world. These areas are of great scientific interest because they are among the world’s most productive environments biologically, and because human interaction with the ocean is concentrated in estuarine regions.

Puget Sound is a large estuary that provides us with an excellent "field laboratory" for studying estuarine circulation patterns. However, the complexity of tidal flow in this area makes a detailed understanding extremely difficult by field observations alone. A physical model of the Sound was constructed in 1950 as a research tool for studying the factors controlling circulation in the Sound. A small-scale model has the advantage of allowing us to observe long-term processes in the space of a few minutes or hours. Many of the physical parameters can be controlled to investigate their effects singly or in combination. For example, river discharge can be set to study the consequences of extreme runoff, tidal action can be set for specific epochs, or anomalous conditions can be simulated. Thus we can predict the circulation patterns that would result from natural or man-made changes in the system. The Puget Sound Model has been used as a teaching aid for marine science classes and for basic and applied research, including pollution studies.

With your Puget Sound group, you will state a hypothesis that is testable by experimenting with the dye and the Puget Sound Model. Unfortunately, we are not able to change the model parameters (tides, river runoff, temperature, salinity, etc.). Therefore, you need to state a hypothesis or question about the current state of circulation in Puget Sound not about how changing parameters might effect the circulation.

You will perform the experiment and take whatever observations you deem necessary.

You will interpret the observations and come to conclusions. Is your hypothesis supported or refuted by the observations?

You will demonstrate your experiment to the class and explain your hypothesis and conclusions.

Each individual will write up an experiment report including:

Hypothesis statement

Description of experiment

Observations (make sure you present your observations in a meaningful way)

Conclusions (explain how the observations support your conclusions)

Further questions (Do your observations suggest further questions?)

Grades will be based both on the individual experiment report (75%) and on the group experiment demonstration in class (25%). Grade will be based on the following questions:

Does the experiment address the hypothesis?

Are the observations well presented?

Are the conclusions supported by the observations?

Did you think about the implications of your results?

Remember that the nature of science is that questions are not always answered to our satisfaction. It is perfectly OK if your conclusion is that the experiment was inconclusive and did not either support or refute your hypothesis. An inconclusive result is much better than a conclusion that is not supported by the evidence. However, if you do have an inconclusive result you should suggest another experiment or a modification of your original experiment that would (hopefully) help address your hypothesis.