Snail Habitat Preference Following Relocation Throughout the Rocky Intertidal: Pretty in Pink Chapter 6 By Julianna Rick and Sara Pratt
Abstract: This study tracks and recovers Common Periwinkles and Dog Whelks in order to observe their choice of habitat when presented with a new one. We marked and relocated snails and moved them to a foreign habitat (Common Periwinkles) and an unprotected one (Dog Whelks). We believed that the Common Periwinkles would return to their original habitat, be found facing in the direction of their original habitat, or will be found in a habitat similar to their original, and the Dog Whelks would not return home but would be found in the closest protected area. We found that the Common Periwinkles did not return home but the Dog Whelks did move to protected areas. This demonstrated the two species relation to community and habitat preference. Introduction: Both Dog Whelks ( Nucella lapillus ) and the Common Periwinkles ( Littorina littorea ) cover the middle and lower intertidal areas of the east coast. The Common Periwinkles have an even more expansive domain ranging from the upper intertidal to 40 meters below the water line. These herbivorous snails are generally found in tidepools, among marsh grasses, roots, in seaweed, and on rocky substrates or grazing on algae. They can and will attach to almost any surface: bottom of boats, ballast stones, rocks, pilings, or garbage heaps. On those surfaces, they love to form colonies. They can be found in groups of 200-800 snails in a square meter (Cohen 2011). Even though there are so many of them it is still hard to locate them due to their camouflage. They can grow up to 38mm and live in thick brown, gray, and blackish shells with 5-8 whorles. Their small shells and whorls protect them from the buffeting of the waves (Cohen 2011). Dog Whelks can be found in areas with greater wave action than Common Periwinkles can withstand, mainly due to the Dog Whelks large muscular foot that grips onto the surface of rocks. If wave action becomes too strong, Dog Whelks make use of sheltered microhabitats in rocky crevices. But even in crevices, Dog Whelks are extremely visible to the naked eye because of their size and color. Dog Whelks can grow up to 6 cm in height and their more unique colors tend to be orange, yellow, pink, blue, and green. They can be found throughout the rocky intertidal because of their hunger for barnacles, which cover large surfaces of rocks (MarineBio Conservation Society 2017). It was not hard for us to find these snails In the intertidal we found both the Dog Whelks and the Common Periwinkles everywhere. Due to the fact that the entire intertidal was their prefered habitat, we had to take the first day and observe their movements and habitats before creating a concrete hypothesis. We observed that the Dog Whelks went from exposed rock to crevices when we moved them from a protected area. From this, we inferred that their main priority would be to protect themselves rather than return to their original habitat. The Common Periwinkles did not have the problem of protection from waves because they are significantly smaller than the Dog Whelks (Sumich 1988). When we relocated these snails, most of them moved in the direction of their original habitat or were found in a similar habitat. From these observations and a study conducted by Robert P. Gendron (1977), we were lead to create these two hypotheses: the Common Periwinkles will return to their original habitat, be found facing in the direction of their original habitat, or will be found in a habitat similar to their original, and the Dog Whelks will not 2017 Chapter 6 1
return home but will be found in the closest protected area. The study conducted by Gendron proved his hypothesis that Common Periwinkles continued to travel back towards their original home. Those groups would share eating, mating, and movement habits. He believed that because of this they would migrate back to their spot if moved in order to find the snail in their group. In his experiment, an entire colony of Common Periwinkles were moved and he tracked each snail s movement. Each day Gendron would returned each snail (that he could find) back to the starting point and track their movements 10 days in a row. He found that each day the snails would get closer and closer to their original home. We believe this study clearly demonstrates that dislocation does affect the direction of the migration for the Common Periwinkles. Our study is important because it will broaden our knowledge of different snail communities and demonstrate snails preference depending on the species priorities, to help understand the structure of the intertidal community. Even though we set out from the classroom having little idea what our hypothesis would look like we were able to utilize the Hurricane Island intertidal and observe first before creating our concrete hypothesis. People had doubts about how we would go about it, but we believe that we created a procedure that would recapture the most snails. ommon Periwinkles C Materials: Dog Whelks Two tape measures A meter stick 4 colors of nail polish Pink base for visibility 2017 Chapter 6 2
3 other colors to differentiate days/data Bucket GPS Note book Pencil Methods: Preliminary Experiments 1. Observe where the Common Periwinkles and Dog Whelks live in the Two Bush rocky intertidal zone 2. Find a habitat for each 3. Mark 20 snails, their shells, but keep them in same location, don t touch/move them 4. Return at next low tide and record how many are found and observe their movement 5. Record how many of each are found 6. Repeat for each day there is an opportunity to return to the tide pool 7. Record how many are found each day Common Periwinkles 1. Locate a colony of Common Periwinkles in the Two bush rocky intertidal zone a. Definition: Very close together, shell touching at least 20 of them, can be up to 200-800 in a square meter 2. Record description of location 3. Mark location with Pink Polish 4. Record GPS location 5. Take pictures for reference 6. Use a measuring tape to mark 2 meters from original location a. Find a location in that area that is different from the original (Will be different for each location and colony of snails) Original New 7. Pick up 20 snails and paint their shells pink and another color to differentiate data and locations 8. Move them to new spot 2017 Chapter 6 3
a. Located in step 6 9. Mark new location with pink nail polish 10. Wait till next low tide 11. Return and attempt to locate all the snails, they hide in seaweed 12. Set up an x and y axis a. Y axis = original to new location and beyond b. X axis = original to the right (left side is negative) 13. Record their location of the X and Y axis 14. Record if they have returned home, are in a similar habitat to original, or neither 15. Record if they are moving in the direction of their original location 16. Put the one's that are already found in a bucket so they are not counted again 17. Use Chi Tests to compare graphs Dog Whelks 1. Locate a group of Dog Whelks that are in a protected are (from waves, a crevice, side of rock, etc. in the Two Bush rocky intertidal zone Protected (original Habitat) Unprotected (New Habitat) a. Not found in large clumped colonies, find a group that has at least 20 in a circle with a circumference of 15 cm 2. Mark Location with pink nail polish 3. Record GPS location 4. Use a measuring tape to mark 2 meters from original location a. Find a location in that area that doesn t have protection, open rock, more exposed to the waves, etc. 5. Pick up 20 snails and paint their shells pink and another color to differentiate data and locations 6. Move them to new spot a. Located in step 4 7. Mark new location with pink nail polish 8. Wait till next low tide 9. Return and attempt to locate all the snails, they hide in seaweed and crevices 10. Set up an x and y axis a. Y axis = original to new location and beyond b. X axis = original to the right (left side is negative) 2017 Chapter 6 4
11. Record their location of the X and Y axis 12. Record if they have moved to a location that is more protected from the waves 13. Put the ones that are already found in a bucket so they are not counted again 14. Use Chi Tests to compare results Results: Common Periwinkles Figure 1a: Shows that the Common Periwinkles do not prefer to go to a habitat similar to their original Chi Test Original to Neither: p-value < 0.05 Original to Similar: p-value < 0.05 Similar to Neither: p-value > 0.05 2017 Chapter 6 5
Figure 1b: Shows that more Common Periwinkles travel in the direction of their original habitat. It is not statistically significant. Chi Test: p-value > 0.05 Dogwhelks Figure 2a: Suggests that more Dogwhelks found protection after being placed in an exposed and unprotected area. It is not statistically significant. This graph includes data from locations 1+2+3+4. Chi Test: p-value > 0.05 2017 Chapter 6 6
Figure 2b: Shows that the majority of Dog Whelks recovered from locations 1+2 did not find protected areas when there were fewer protected options available and that the majority of Dog Whelks offered protected options found them. It is statistically significant (p-value <.05) Locations 1 and 2 were areas covered in seaweed that we did not define as protection. The only possible protected option was a small crevice far away from the locations. Locations 3 and 4 offered protected options such as crevices and wave sheltered rocks. Location 1+2: Chi Test: p-value < 0.05 Location 3+4: Chi test: p-value < 0.05 Discussion: Unfortunately, we were not able to prove our hypothesis. Originally we thought that the Common Periwinkles would return to their original habitat, be found in similar habitat to their original, or be found moving towards their original habitat. We have concluded that none of our results are significant. Numerically we had more snails going in the direction of their original habitat, but when we performed the chi test, our results were well above.05 as shown in Figure 1a. As for the Dogwhelks, we thought that they would find protected options and we were right. They choose to move towards shelter in general rather than back to their original habitat. Our Dog Whelk results are broken into two graphs, one for the overall results from all four locations shown in Figure 2a and another for the locations that offered few protected options and many protected options shown in Figure 2b. When there are not protected options available they are unable to protect themselves. In contrast, when there are protected options, they go to those protected areas. Our error with properly testing the snails from locations 1 and 2 turned into a great comparison for us to look at. We now believe that Dog Whelks natural instinct is to protect themselves and Common periwinkles are more likely to find another colony of Common periwinkles. When we found our Common periwinkles, the snails were in areas that had colonies or smaller groups of periwinkles. When we found the Dog Whelks, the snails were in 2017 Chapter 6 7
protected areas or had moved far away from their new habitat, we believe, to find a protected location. Coming into the experiment our research suggested that there would be distinct habitats for each species, but we found them everywhere in the intertidal. Because of this, our experiment was based on the experiment done by Gendron, but they were not as isolated as we wanted or were expecting. His experiments were conducted in a set location that had a significant separation from other locations. Our experiment had many possible locations that could draw the snails making is hard to choose where to place them. This could be a source of error because they would be more drawn to different colonies than focusing on their own. Other sources of error were time and our environments. We would paint our snails and then recover them the next day but each lowtide was not at the same time so there wasn't an even amount of time spent between painting and recovering for each location. There also wasn't an even amount of time looking for the snails. We would search until we believed that we had done our best and that changed as we grew tired of looking for snails. For future groups we suggest that there is a set time designated to each location. We believe that 20 minutes would be sufficient. Also if people were to continue this experiment we wanted to make known that it is extremely tiring and draining to look for these snails every day so keep your motivation up! Not only was it difficult to find the snails because we were tired, we also found it difficult to find all the snails because crevices were deep and there were other intertidal obstacles. The intertidal was also covered in seaweed and we had to be careful because the Common Periwinkles liked to latch on to the seaweed. When we moved the seaweed to look at the rock underneath we risked moving snails with it. So for people going into the field be ready to completely embrace the intertidal but also be careful when jumping around rocks and bending down to reach crevices. We would suggest that when choosing locations people should avoid seaweed and choose areas that are flat and do not include much climbing. Other small tips for people interested in continuing a project like this would be to keep conscious of the movement of your measuring tape, try to keep it as accurate as possible, and know that nail polish does allow you to recover 75% of your snails. We used nail polish because we deemed it the most efficient tagging system but we had to use bright colors because it was hard to find them otherwise. But also remember that this bright color could have attracted more predators and the paint could have easily chipped off. People replicating our study should consider doing our preliminary experiment again but with a defined radius in which to look. We just tried to find as many as we could but sometimes the dog Whelks would travel extremely far. After completing this experiment we are still are very interested and have many ideas for future studies that go further than our study. Gendron s study involved recovering snails and then placing them in the same spot for multiple days in a row and we believed that a study similar to his would be interesting as well. Even though we have areas of improvement and expansion we were still able to evaluate the behavior of snail communities. This experiment provided an understanding and further knowledge of Common Periwinkle s and Dog Whelk s behavior when placed in an unexpected situation. We found that Dog Whelks are independent and prioritize protection. The Common Periwinkles are more dependent on a colony based habitat rather than an ideal protective habitat. We learned that their communities are not as 2017 Chapter 6 8
colony based as we first expected and that they are more independent than our research expected. Bibliography: Cohen, Andrew N. 2011. The Exotics Guide: Non-native Marine Species of the North American Pacific Coast. Center for Research on Aquatic Bioinvasions, Richmond, CA, and San Francisco Estuary Institute, Oakland, CA. Revised September 2011. http://www.exoticsguide.org "Dog Whelks, Nucella lapillus ~ MarineBio.org." MarineBio Conservation Society. Web. Accessed Thursday, June 01, 2017. <http://marinebio.org/species.asp?id=536>. Last update: 1/14/2 013 2:22:00 PM ~ Contributor(s): MarineBio Gendron, R. (1977). Habitat Selection and Migratory Behaviour of the Intertidal Gastropod Littorina littorea (L.). Journal of Animal Ecology, 46 (1), 79-92. doi:10.2307/3948 Sumich, James L. An Introduction to the Biology of Marine Life. 5th ed. Dubuque, IA: W.C. Brown, 1988. Print. 2017 Chapter 6 9