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Bio 140 Discussion Assignment


The objective of our study was to determine if salinity affects theLittorina sp.’s movement. In both of our two trials, we found that when exposed to a lower salinity (10 ppt), theLittorina sp.had a lower displacement than when it is exposed to a higher salinity (30 ppt). We observed that at 10 ppt theLittorina sp.would either move slowly or not move at all. This was congruent with our prediction that theLittorina sp.would have a lower net displacement in a lower salinity. Our results may have been influenced by our constant movement around the containers which changed the intensity of the light that theLittorina sp.wereexperiencing. Studies have shown thatLittorina sp.are positive phototrophs, meaning that they gravitate towards a light source (Bingham, 1972). Because of this it is reasonable to assume that constant changing light intensities and directions of light source would affect where theLittorina sp.would move to, affecting our results.
In Bingham’s study in 1957 it was found thatLittorina sp.could survive in 10 ppt salinity for up to two weeks, but when introduced to low salinity environments in their natural habitat it as found there was a sharp decrease in population density since the snails had moved into a different micro-environment to avoid the stress of a low salinity environment(Bingham, 1972). This means that low salinities did indeed prompt movement inLittorinasp..This was inconsistent with our results.
The study conductedbyMuraeva, O.A.,Maltseva, A.L.,Mikhailova, N.A. and Al. CellTissin 2016 showed that when subjected to lower salinity levels the snails would retreat into their shells,effectively isolating themselves from the source of stress (low salinity). We observed in our trials that when snails retreated into their shells they stopped moving for the entirety of the duration within the shell(Muraeva, O.A.,Maltseva, A.L.,Mikhailova, N.A. and Al. CellTiss, 2016). According to this study lower salinities reduced the movement of theLittorina sp..This was consistent with our results.

Our findings were consistent with one of the literary sources but inconsistent with the second. This was because of the methods in which theLittorina sp.were subjected to the lower salinities. In our study as well as that that was conducted byMuraeva, O.A.,Maltseva, A.L.,Mikhailova, N.A. and Al. CellTissin 2016, theLittorina sp.were introduced into a low salinity environment quite abruptly within a laboratory, theLittorina sp.’sprimary reaction to stress (Muraeva, O.A.,Maltseva, A.L.,Mikhailova, N.A. and Al. CellTiss, 2016)is to retreat into their shells, and stop moving. This was what we observed in our trials.
In Bingham’s studies however it was done over a six month period of time and the snails were introduced to an environment in which they could indeed move into a different micro-environment. It is safe to assume that when initially introduced into the low salinity environment they retreated into their shellsand because they cannot survive for more than two weeks (Bingham, 1957) in a low salinity environment, theLittorina sp.eventually had to move into a different micro-climate eventually to avoid quietus.
In conclusion, it was decided that the discrepancies between studies and our trials was due to the variance in timeframe of the study as well as where theLittorina sp.were studied. We believe that both literary sources support our study (whether directly or indirectly) since it is shown thatLittorina sp.retreat into their shells and thus have a lower displacement whenoriginallyintroduced into a low salinity environment outside their range of tolerance (Bingham, 1957).

Because theLittorina spp.resides within the intertidal zone it is subject to a constant fluctuation of environmental factors such as salinity due to fluctuations in the amount of freshwater introduced into the system (rainfall,streametc.) . This has large implications for the survival of the periwinkle as it is an osmoconformer. Meaning the presence of various chemical entities within its cells is in direct correlation to the