With global warming comes a number of side effects our earth must endure, one of them being a decline in surface water ocean salinity. “But what could this possible mean?” you may ask. Well it means that the salinity in the intertidal zone is also decreasing, and intertidal organisms such as marine, who are intolerant to low salinities may affected. Poor snails.
I wanted to see how marine snails would respond in low salinity water, knowing that they don’t like it, and if overtime they could get used to it and emerge from their shells.
To do so I used black turban snails collected from Wreck Beach at UBC to test their response in high and low salinity levels, as well as their preference to high or low salinity, and if being in low salinity over time would affect their temperature preference.
The snails were held in two separate bottles, one had high salinity water (35ppt) and the other had low salinity water (20ppt). Some snails remained in the bottles for just 3 day and another group of snails were left for a week. After a week they looked like this:
The snails on the left were the ones in the high salinity water and the snails on the right were kept in low salinity. As you can see many of the snails in the bottle on the right didn’t like it that much and most of them stayed in their shells.
So I started of the experiments by dropping the snails into the high salinity water and the low salinity water to see what they did. If they came out of their shells, I considered that a response, and if they remained hidden away, that was no response.
After all the snails had been dropped in both types of water, I ran some fancy-schmacy statistical tests and found that there wasn’t anything significant about the snails’ response in high salinity, in low salinity, significantly more snails responded when they were held or acclimated for a longer period of time. This could mean that if kept at low ocean salinities over time, black turban snails can start to tolerate the environment and start doing their thing again.
Next I tested their preference for the high or low salinity water when given the choice. I placed them in petri dishes with two pieces of filter paper on each side, one soaked with high salinity water and other soaked with low salinity water, and then I let them wander for 10 minutes.
I ran the stats and found that snails tended to choose the salinity they were kept at, but the snails kept for a week chose high salinity more often. So even though they got used to their water salinity, they still preferred the higher salinity of the two.
Finally, I made these bun tin foil boats and placed them on bags of ice and hot water so one side would become warm and the other cold. I then placed the snails in the middle and left them for 20 minutes and came back to see what side of the boats they were on.
I expected all the snails to be on the warm side if the salinity didn’t affect them, and if the salinity did affect them, I expected the snails held in the low salinity to not be found on the warm side as often as the snails held at the high salinity. However my results showed that the snails had no temperature preference, even those held at the high salinity. This could either mean that salinity does not play a role in this behaviour, or that I need to tweak my methods for a better experiment. Either way, I’d like to see what would happen if this was tested again.
In the end, I learned that black turban snails are dope and can begin to tolerate salinities that weren’t having any part of before. Word G-man.
So even though the ocean salinity is decreasing, it appears that our snail friends in the intertidal will be okay, and the other molluscs might do fine as well. This however does not account for the increase in ocean temperature or pH, so the snails may still be in danger.
Continuing studies on the effects of the changing ocean on these intertidal organisms may help us find a way to protect our aquatic friends, like Gary.