Is that a message in a bottle? No, that’s my Biology 326 lab experiment!

On Wednesday Sept. 24th we built mini environments to learn about the herbivory rates of the marine snail Chlorostoma funebralis. For a little backstory, let’s think about the importance of herbivores. Just a recap, herbivores are animals that consume primary producers, such as plants and algae. Herbivores can have a huge impact on the structure of communities. When an herbivore is dominant in a community it can consume so much of a plant or algae species that it can be reduced or completely removed from a community. An example of this are urchin barrens.

Kelp canopy - (c) Ocean Defenders Alliance

Kelp forest. Photo Credit: Ocean Defenders Alliance

Urchin Barrens (c) Ocean Defenders Alliance

Urchin Barrens. Photo Credit: Ocean Defenders Alliance

Without sea otters to keep down the urchin population, urchins can completely decimate a kelp forest. Learn more about sea otters, urchins and kelp forests in B.C. This can have numerous consequences, on the kelp itself and on other species that either use the kelp forests as habitat or as food. In other situations herbivory can help to create diversity by reducing the presence of a competitive plant or algal species. If an herbivore can keep the size of a kelp population down, that can make space for other less dominant algal species which increases species diversity in a community. As you can see, herbivores play an important role in communities, and one of our favourite communities in Biology 326 to think about is the marine intertidal zone, so let’s find out what kind of herbivory is happening there.

A common marine herbivore in the rocky intertidal of British Columbia is the black turban snail, Chlorostoma funebralis and one of its favourite meals is the kelp, Nereocystis luetkeana. We set out to test the effects of temperature on the rate of algal consumption by black turban snails on Wednesday Sept. 24th 2014. We know that temperature increases the energy demands of animals, so we predicted that at higher temperatures the snails would consume more algae. To test this, we built mini environments in plastic bottles with kelp.

Not just another message in a bottle! Photo Credit: Rhea Storlund

Not just another message in a bottle! Photo Credit: Rhea Storlund

We had four different treatments; cool with and without snails and warm with and without snails. We planned to leave the snails to eat for a week, but it turns out the experiment took only 48 hours. In the end, temperature did not change the rate at which the snails consumed algae.

We decided to check to see if temperature did in fact affect the snails in other ways using three measures of activity, the number of bites of algae that a snail takes per minute, the time that it took for a snail to right itself when placed on its shell, and the distance that it travels in a minute. The number of bites of algae that the snails took per minute did not vary with temperature, which might explain why we didn’t see more algae being consumed at higher temperatures. The snails’ righting time also did not change with temperature. We did however see that snails move faster at higher temperatures. So now we know that “moving at a snail’s pace” really depends on the temperature of that snail’s environment.


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