Size (health) of Snails in Relation to Human Impact

By: Julia Pollard, Abbie Titcomb, Sara Sweeten, Amanda Richards

Question: In what ways and to what extent is the size of periwinkle snails affected by

water salinity/the runoff pipe located at Town Neck Beach, Sandwich MA?

Importance of Research: -Fresh water run-off pipe could have a significant effect on the health of snails

in the entire ecosystem, which could in turn affect the ecosystem in general (regarding predator-prey relationships and the niches of individual organisms).

-The health of the snails could be an indication of further health concerns inflicted by the run-off pipe water.

Implications of Human Interference: -The run-off pipe at the Town Neck beach has resulted in the stunting of

growth of periwinkle snails, even death. The ecosystem is therefore affected negatively, because of the predator-prey relationships (seen above).

Research Question

Fresh-water Pipe:1. Collect 50 snails from along the stream banks

created by the fresh water pipe

a. Measure size of snails

b. Take note of where specifically snails are found (ex. in the water, on the mud bank, etc.)

2. Take water samples along the stream from three different locations, where snails were found

a. Note where the water samples were taken from3. Measure salinity of water samples taken

a. Note the change in salinity as the distance from the pipe increases

4. Make observations about the relationship between size of snails, their location, and salinity

a. How can these three factors demonstrate how freshwater (human impact) affects periwinkles?

Saltwater Creek:5. Same process as above, but with one water sample

instead of three

Data Collecting Process

Salinity (was measured at three locations of stream where freshwater pipe flowed into):

Beginning of stream: 3.3 pptHalfway through stream: 19.4 pptEnd of stream: 21.0 ppt

Snail Collection:

12/50 snails collected alive, 38/50 snails collected dead

Fresh Water Pipe Data

Average Sizes (cm)

All snails 2.22

Dead snails 2.28

Alive snails 2.21

Salinity (was only taken at one location as the salt water creek turns into a large body of water):

Average of 3 water samples taken: 30.1 ppt

Snail Collection: Unlike in the fresh water pipe creek, all of the snails collected were alive. The average size of 50 snails in this area was 1.80 cm.

Saltwater Creek Data

• Based on the data collected it is very clear that the freshwater run-off pipe has a very negative impact on snails. While no clear trend in shell size of the snails was observed, a clear trend was indicated between the number of dead snails found and the number of living ones.

• All of the snails located near the freshwater pipe located in the water were dead. All of the alive snails near the pipe stayed on top of the marsh.

• All of the snails found in the saltwater creek were alive, no dead snails were found.

• Salinity level near the freshwater pipe 3.0 ppt, Salinity near the saltwater creek 30.1 ppt.

• Negative human impact from the freshwater pipe, Snails survive better in areas of higher salinity.

Conclusions

Collaborative approach to developing a research question:

Sara: Note-taker, group documenter / data recorderJulia: Snail and sample collector, took salinity

measurementsAmanda: Snail and sample collector, took salinity

measurementsAbbie: Took snail size measurements, snail collector

Group Collaboration