Results & Conclusion

Our results indicated that the population estimate is around 99,800 individuals with a 95% confidence range of 95,616-103,985 individuals in the 1000m^2 area. This results in a density of 25.15 individuals per meter squared. While taking the data, we realized that it would be impossible to gather an entire census, as the population is so dense and environmental factors such as the tide would limit our abilities. This method was the best way to go. If we had used a transect model, the data would have been skewed, as the population density was not equally spread over the sample area; there were less snails present on the rocky shore than in the tide pools, and the most directly in the surf edge.
The population estimate method we employed could be easily used for many other locations in Montana de Oro State Park, Morro Bay, and even along he coast of California. These methods could also be utilized over time to provide an accessible understanding of the population dynamics of the Tegula funebralis Gastropoda snail. Although the turban sea snails are not endangered, using their population dynamics model, data could be extrapolated to draw inferences on populations both interacting and depending upon the turban sea snails. They could also be used in conservation efforts to provide sanctuary to other endangered species.

Table 1. The actual counts of the individuals found in each of the 20 quadrate sampled.

Table 2. The statistical data of the population estimate generated from the mean of the individuals from Table 1 and the study sample area of 1000m^2.

Methods

To estimate the population size of turban sea snails in the study area, we used quadrat sampling.  A spool of twine was marked at every meter, and a random number generator was used to select the coordinates of the quadrats sampled.  The twine was used to measure the study area (20 meters x 50 meters) and locate the coordinates of each quadrat, then the twine was formed into a square with 0.5 meter sides to sample.  All individuals were counted within the 0.25m² quadrat, with those on the edges counted in the quadrat if they were more than halfway in the sample.  A total of 20 samples were taken over a period of 60 minutes to ensure a closed population through the data collection. 

Tide pooling!

Wednesday we went out to turn our pilot study into a real experiment. We opted for the tide pools in Montana de Oro state park, as they seemed more accessible and feasible for our study. We walked down to the bluffs by the Badger trail. I measured the total area to be around 0.15mi in length by running as close as I could on the perimeter. The tide posed an issue of width, but we went out as close to low tide as we could, and it seemed to be minor while sampling. Measuring the length in meters by twine proved simple and effective. The random number generator gave us coordinates along our twine axis and then further down our width axis. From the point on the horizontal twine, we walked out to various points to set up the quadrat. With an incoming tide obstructing the view and changing the environment, we opted to only count 10 quadrats 0.5m squared. We counted as fast as we could, but in the end it is only an estimate. We have to acknowledge that there is a probability of detection involved; not all turban snails could have been seen or present. I would call it a successful sample because the random number generator spread our samples over a wide variety of spots in the area, and the data seemed cohesive.
- Kelsie Clausen

Here are some photos I took of the day:

The study area

The turban snails counted

Tide pools stretched longitudinally

A typical view of a quadrat sample

Marking the twine in meters

Counting the distance horizontally