We’ve all seen the city lights after a night out and thought “Wow, those look really nice!” Humans might find city lights pretty, but is the same true for animals that also look at those lights? Light pollution is becoming a bigger issue for nocturnal animals. Recent studies suggest that birds, bats, insects and other creatures that come out at night find lights to be confusing and disorienting, considering these animals only had the light of the moon to show them the way at night, before humans came along. But what about marine animals? What about the critters that are lit up by waterfront buildings and streetlights? Do they like it? Well, to find out, I subjected some snails to constant lights for four days!

My choice of marine invertebrate was the checkered periwinkle Littorina scutulata because it is a common intertidal herbivore and recent studies suggest that artificial light does negatively effect their movement performance.

For this experiment I went down to Tower Beach near UBC with a 4 gallon bucket to collect some seawater, algae and some live Littorina. I went to Tower Beach because I wanted to find snails that have never seen artificial light before. After spending about two hours looking for snails I found about 30 snails hiding in dead barnacle shells! I then brought them home in the bucket and left them in there for a day so they’d be acclimated to being in a smaller container. Next I separated the snails into three 10L aquariums. One of these would be the control so it wouldn’t get any artificial light at night. The second would be exposed to red LEDs at night, like those emitted from buildings. Finally the third aquarium would be exposed to soft white light at night, like the light emitted from streetlights. I exposed the snails to this light cycle for four days.

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After light exposure I transferred the snails to a shallow tupperware container filled with seawater. I placed the snails upside down and measured the time it took for them to turn themselves the right way up because it tells us how active the snails are. I also measured how fast snails crawled after they were the right way up.

After all my measurements and data analysis, I found that artificial light exposure for four days did not affect how active the snails were, which was surprising and against my predictions. However, I also found out that crawling speed was affected by light exposure! Snails exposed to soft white light were slower than control snails.

Here’s why my results are important: if we continue on this path we face altering the nigh-time behaviour and activity of snails and other organisms with eyes. These changes could include how organisms interact with each other at night or even their abundance, i.e. how many of them are out there.

But enough about what I did, so here are some links if you want to learn more about light pollution and marine light pollution:

Last week our BIOL 326 class took part in a virtual field trip organized by the Bamfield Marine Sciences Center. During the tour we had the opportunity to look at the huge variety of of intertidal marine organisms living around the research center in Bamfield, BC.

What is the intertidal zone?

The intertidal zone can be found on any shore with a tidal body of water. During high and low tide organisms experience higher temperature and salinity variations in addition to longer times exposed to air and direct sunlight. On top of all these factors, organisms, especially those that cannot move (i.e. sessile) also have to compete for space. This combination of biotic and abiotic factors result in high competition and distint levels of the intertidal zone being occupied by different organims. This is what intertidal biologists call “zonation”.

Image source:https://www.pinterest.ca

What we saw at Bamfield?

At Bamfield we had an opportunity to look at both the rocky intertidal and also tide pools that emerge during low tide.

The Grainyhand Hermit Crab

This little critter is one of the common inhabitants of the intertidal, it can be easily identified by the blue dots on its body and also the orange-coloured antennae. Like other hermit crabs they do not make their own shells, but rather use shells discarded by marine snails that do make shells!

Speaking of shells, in Bamfield you’ll see hermit crabs using shells from Black Turban Snails and Dire Whelks that are also found in the intertidal. The Black Turban Snail is a herbivore and feeds on algae, whereas Dire whelks are predatory and feed on other snails by using their radula, a nail file-like tongue that can drill holes in shells!

Black Turban Snail on the left (Image source: https://www.centralcoastbiodiversity.org/black-turban-snail-bull-tegula-funebralis.html) and Dire Whelk on the right (Image source https://inaturalist.ca/taxa/117642-Lirabuccinum-dirum)

Porcelain crabs are also one of the species we saw at Bamfield. When the tide goes out, they like to hide under rocks where it’s still wet which means they have an easier time breathing. Even though crabs venture onto land they still use gills to breathe, so keeping them wet is very important for the crabs. Porcelain crabs, despite their name are not true crabs. They technically classify as false crabs due to having one fewer pair of walking legs than true crabs, which have four.

One other cool thing about porcelain crabs is that they can remove limbs at will! When they are attacked by an animal that wants to eat them they can detach a limb to confuse their predators, but don’t worry they can grow them back as they continue to molt.

Why is the intertidal important?

The intertidal zone maintains a balance between the land and the sea. It provides a home to specially adapted marine plants and animals. Those organisms, in turn, are part of the complex food webs of many other animals.

The intertidal zone also stops erosion caused by storms. Oyster reefs are one such example that prevent the endless battering of the waves on shore from damaging natural and artificial structures on the shore

All of the animals I mentioned are only a small part of the intertidal ecosystem. No blog can help you to truly understand the diversity and beauty of the intertidal, to accomplish that you need to go outside and see it for yourself. Remember to put everything you find back where it belongs!

In the meantime you may want to watch this documentary on the intertidal, it even features UBC’s own Dr. Patrick Martone!

https://www.cbc.ca/natureofthings/episodes/kingdom-of-the-tide

It is wintertime and the weather is getting undoubtedly cold. While you may enjoy the cold weather wrapped in blankets and your choice of hot beverage, others are not as lucky. Many organisms that live in the intertidal, a region of the coast that is underwater during high tide and above water during low tide, experience a constant cycle of being exposed to cold water and even colder air. Since they cannot escape the cold, intertidal organisms have to find a way to deal with the cold: enter “Freeze Tolerance”, the ability of an organisms to survive freezing temperatures.

Why is freeze tolerance important?

Some things we discussed in my BIOL 326 lab about freeze tolerance resulted in some pretty reasonable arguments and I’d like to share them here. Studying freeze tolerance can help us understand what limits the spread of an organisms’ range towards the poles. It can also help us  predict what might happen to ecosystems if extremely cold weather occurs. Understanding the mechanisms behind freeze tolerance can even lead to the creation of novel techniques that can be applied to cryopreservation of cells, tissues, and even organs.

All images taken from https://inverts.wallawalla.edu

Two organisms we looked at were intertidal organisms from the Burrard Inlet: an intertidal barnacle (Balanus glandula) and an intertidal snail (Littorina scutulata). Both of these organisms are invertebrates, but B. glandula belongs to the group (or subphylum to be exact) “Crustacea”, which means that they have more in common with animals like crabs and lobsters! L. scutulata on the other hand belongs to the group (or phylum) “Mollusca” so they are more closely related to mussels, clams, whelks etc.

To understand the extent of freeze tolerance in these two organisms, we collected barnacles and snails from the Jericho Yacht Club and brought them to the lab. In the lab they were exposed to different temperature water ranging from -5 to -10 ℃ for several hours. At the end of their freezing cycle, all barnacles and snails that were frozen were given some time to acclimate to regular seawater. After this acclimation period was over, we collected several different types of data to see how freezing had affected our snails and barnacles. For snails we measured the time it took for them to right themselves after they had been turned upside down and also the distance they traveled per minute. For species that cannot move, like the barnacle, we opted to measure the proportion of barnacles that exhibited feeding behaviour by extending their “cirri” (a modified foot!) and also the frequency of this behaviour.

What remains now is to analyze the data that was collected, but meanwhile if you want to learn more about freeze tolerance, here’s a talk by UBC prof Dr. Katie Marshall: https://www.youtube.com/watch?v=aYFM6UXY-XQ