At-Home STEM Activities: SAV Services
As we look at the evolution and importance of plants this week, let’s focus on some flowering plants that took an interesting step back into the water. Submerged Aquatic Vegetation (SAV) includes aquatic grasses- these are plants that grow almost completely in water (one genus produces flowers above the water- the rest have underwater flowers pollinated by water movement!) even though ancestral flowering plants evolved on land.
Photo courtesy of NOAA
Sea grasses and other SAV provide a number of ecosystem services, making them an important part of aquatic habitats- in addition to being a habitat for other aquatic species, they help oxygenate water, cycle and recycle nutrients, dampen wave energy, and trap sediment. All of this together helps improve water quality and reduce land loss.
You can see for yourself how sea grass ‘meadows’ change water flow with a just few items probably on hand in your home.
For this activity, you will need:
-container for water
-water
-1 or more combs
-something to generate waves- I used a small cup, but you could try a variety of things including a potato masher, plastic toy, or even a small rain boot
-ground black pepper
-white surface to place the container on if it’s clear (I put paper underneath my dish)
-tape or something else to help hold the combs upright
Place the largest comb in the container so that it is standing on its teeth and touching two of the container’s sides- I used tape to keep it in place- you could also hold it in place if needed
Stand up any additional combs in the small area blocked off by the big comb
3. Fill container so that the water comes partly up the teeth of the comb but does not reach the shaft
4. Use the small cup/toy/other wave-maker to create waves by moving it up and down in the largest section of the container- notice what happens when the waves hit the combs and the size (amplitude) of the waves on either side of the combs
5. Let the water become calm again and then sprinkle ground pepper on the surface- once again make waves and notice how the pepper moves around. Some of the pepper will settle to the bottom when the water stops moving- was there any place that it bunched up as it settled out?
6. Try experimenting with different comb configurations and see how that changes your results
What happened?
Water and wave energy were deflected and absorbed by the sea grass (comb teeth) so that the area behind the combs was protected- sea grass does the same thing for our coasts which helps prevent erosion. When water slows as it encounters sea grass, sediment it’s been carrying falls out to replenish the sea bottom.
