Tiger Nerite Snail Conversion from Freshwater to Marine

I am currently conducting an experiment to investigate the ability of Tiger Nerite Snails to transition from freshwater to full marine conditions.I have already conducted the initial experiment myself, and the results have produced a rather unexpected observation.

My Experimental Results​

I tested two different methods of transferring Tiger Nerite Snails from freshwater into a marine environment:1. Drip acclimationThe snails were gradually acclimated from freshwater to marine conditions using a conventional drip-acclimation process.I observed approximately ~20% mortality in this group during the process of acclimation.2. Direct transferThe snails were transferred directly from freshwater into the marine aquarium, without drip acclimation.In this group, I observed ~3% mortality during the process of acclimation.The difference was unexpected. Based on conventional aquarium practice, one would generally expect gradual acclimation to be the safer approach when making a significant change in salinity.However, my observations suggest the opposite may be happening with Tiger Nerites.

Observation​

The interesting part was not simply the difference in mortality.During the direct-transfer process, I observed that the snails would withdraw into their shells and seal themselves with their operculum after being introduced into the marine environment.They effectively closed themselves off from the surrounding water.This led me to consider whether the snail's natural response to sudden environmental changes might actually be helping it manage the transition.In contrast, during drip acclimation, the surrounding water is continuously changing as freshwater is gradually replaced by increasingly saline water.This creates a very different environmental exposure for the snail.

My Hypothesis​

My current hypothesis is that the Tiger Nerite may be capable of performing a significant degree of biological/osmoregulatory acclimation while sealed inside its shell.When transferred directly into marine water, the snail immediately closes its operculum, effectively isolating itself from the external environment.My hypothesis is that this allows the snail to undergo its physiological adjustment to the new osmotic conditions in a more controlled manner.With drip acclimation, however, the environmental conditions surrounding the snail are continuously changing.Instead of experiencing one major environmental change followed by a period of internal physiological adjustment, the snail is repeatedly exposed to changing salinity.My theory is that this may interfere with, or repeatedly restart, the biological/osmoregulatory acclimation process for the snails and therefore place greater physiological stress on the animal.This could potentially explain the result I observed during the transition:Direct transfer → approximately 3% mortality versusDrip acclimation → approximately 20% mortalityI want to make it very clear that this is currently only a hypothesis.I am not claiming that I have proven the mechanism.The mortality difference I observed is what prompted the hypothesis in the first place.What I now want to determine is whether the same result can be reproduced by other aquarists under controlled conditions.

Why Tiger Nerites?​

There is another interesting aspect to this species that makes this experiment worth investigating.Tiger Nerites are commonly sold around the world as freshwater aquarium snails. They are also well known for laying eggs in freshwater aquariums.Yet these eggs generally do not successfully hatch and develop in freshwater.The hatching and larval stage requires a higher-salinity environment for successful development.This raises an interesting biological question regarding the species' actual relationship with salinity.The reproductive cycle requires a saline environment for larval development.And, more importantly, how does the adult animal physiologically handle a transition between freshwater and marine conditions?That is what I am trying to investigate.

Request for Community Participation​

My own experiment has produced an interesting result, but the sample size is not large enough for me to determine whether this is a genuine and repeatable phenomenon.I am therefore asking aquarists around the world to help me replicate the experiment.I am specifically requesting participants to conduct a controlled comparison using 20 Tiger Nerite Snails.The 20 snails should be divided into two groups:

Group A — Direct Transfer​

10 Tiger Nerite SnailsTransfer the 10 snails directly from freshwater into the marine environment without any acclimation.

Group B — Drip Acclimation​

10 Tiger Nerite SnailsTake the remaining 10 snails and perform a conventional drip acclimation from freshwater into the same marine conditions.The important measurement is mortality during the conversion process itself.Once the conversion has been completed, both groups should ideally be maintained under the same marine conditions.

Special Directions:​

- For drip acclimation, continue the process till the final water level has risen to 4 times the original freshwater - Use saltwater from the same tank for both groups to make sure the end parameters remain same not compromising the end parameters

Data Collection Blank Template​

Participants can copy and use this blank template to record their data:

My Recorded Experiment Results​

Here are my actual findings for reference:

Since the table i provided above to input the results was not posted properly due to column length allignment issues, below is the table for easy use. i am attaching a word document for the same here for easy download and filling up the data along with the instructions and other details for easy use

Very interesting experiment. By Tiger nerite, are you referencing Neritina semiconica?


My understanding is this species is amphidromous and spends most or all of its adult life in freshwater rather than marine conditions.

So it would make no sense for their eggs to be unable to hatch in freshwater.

I have some photographic evidence showing the differences between unhatched nerite oothecae and hatched oothecae in freshwater.

It is unfortunate that I cannot be sure which species produced any of the oothecae in my images.

The images I took myself show oothecae laid either by Neratina semiconica or Vittina natalensis (zebra nerite). One image is by another member here and I’ve no idea what species produced them.