The activities are as follows:
- Teacher Guide
- Student activity, Graph Type A, Level 3
- Student activity, Graph Type B, Level 3
- Student activity, Graph Type C, Level 3
- Grading Rubric
- Optional classroom reading: Harriet Booth: Unraveling the mysteries of Plum Island’s marshes
Salt marshes are among the most productive coastal ecosystems. They support a diversity of plants and animals. Algae and marsh plants feed many invertebrates, like snails and crabs, which are then eaten by fish and birds. This flow of energy through the food web is important for the functioning of the marsh. Today, we are adding large amounts of fertilizers to our lawns and agricultural areas. When it rains these nutrients runoff into marshes. Marsh plants and algae can then use theses extra nutrients to grow and reproduce faster. Changes in any links in the food chain can have cascading effects throughout the ecosystem.
To understand how these nutrients will affect the marsh food web, scientists working at Plum Island Marsh experimentally fertilized several salt marsh creeks for many years. In 2009, they noticed that fish populations were declining in the fertilized creeks. Because fertilizer does not have any direct effect on fish, they wondered what could fertilizer be changing in the system that would affect fish? That same year they also noticed the mudflats in the fertilized creeks were covered in mudsnails, far more so than in previous years. These mudsnails eat the same algae that fish eat, and they compete for space on the mudflats with the small invertebrates that the fish also eat. The scientists thought that the large populations of mudsnails were causing the mysterious disappearance of fish in fertilized creeks by decreasing the number of algae and invertebrates in fertilized creeks.
A few years later, Harriet began working as one of the scientists at Plum Island Marsh. She was worried mudsnails were getting a bad reputation. There was no evidence to show they were causing the decline in fish populations. She decided to collect some data. If mudsnails were competing with the invertebrates that fish eat, she expected to find high densities of mudsnails and low densities of invertebrates in the fertilized creeks. In the summer of 2012, Harriet counted and collected mudsnails using a quadrat (shown in the photo), and took cores down into the mud to measure the other invertebrates in the mudflats of the creeks. She randomly sampled 20 locations along a 200-meter stretch of creek at low tide. The data she collected is found below and can help determine whether mudsnails are responsible for the disappearance of fish in fertilized creeks.
Featured scientist: Harriet Booth from Northeastern University
Click here for a great blog post by Harriet detailing her time spent in the salt marsh: Harriet Booth: Unraveling the mysteries of Plum Island’s marshes