Taking Without Permission (a.k.a. Stealing)

A huge sign at the Royal Vancouver Yacht Club entrance says “members only”. How can we get in without paying for membership? Be part of the BIOL 326 class! Earlier this week, our class was on a mission to find some native and invasive invertebrates. What better way to spend a beautiful afternoon hanging over the edge of the deck looking for invertebrates (without falling into the water!). Before we dive in and talk about our interesting observations, let’s understand what invasive species are and where to find them.

Just like the French colonists who colonized North America in 1534, invasive species are introduced to a new habitat and drive the native species to vulnerability. They can compete for food and/or space with the native species. One of the invasive species that we investigated during the lab was the golden-star tunicates. They are named for their star-shaped colonies. The other species we collected was the Japanese skeleton shrimp that holds onto sea plumes. We looked for them at fouling communities, which are communities on artificial surfaces like docks, rocks, boats, and marinas. The reason why we chose fouling communities to study invasive species was because fouling communities are especially vulnerable to invasive species.

During the lab, we were split into two groups to go to two locations of Royal Vancouver Yacht Club that have different salinities. My group went to the one at Jericho Beach, and we did not find any invasive tunicates (which is a good thing!) but the other group did at Coal Harbour. (Hmmm…I wonder if their survival depends on the ocean salinity…) They also collected some colonies back to the lab so we could look at the them closely under the microscope. The subtle movement of the tunicates were quite interesting. When we looked carefully, we could see the water movement in through the siphons and through the bodies!

(more about golden-star tunicates from Fisheries and Ocean Canada: http://www.qc.dfo-mpo.gc.ca/publications/envahissant-invasive/botrylle-etoile-golden-star-tunicate-eng.html)

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Golden-star tunicates! Aren’t they gorgeous! (www.exoticsguide.org/botryllus_schlosseri)

While the other group found the golden-star tunicates, my group found the Japanese skeleton shrimps! They were hard to find because they are so tiny (~3mm) not very abundant. It was easier to look at them under a microscope in the lab. The one that my partner and I observed under the scope was pregnant! When we zoomed in even closer, we could see her tiny heart beating (212 beats per minute!). After a few minutes of observing our skeleton shrimp, she stopped moving, and her heart stopped! We thought it might be the lamp of the scope that was warming up the water. After we changed the water, she returned to life! It seemed like Japanese skeleton shrimp survival depends on the water temperature…

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The swelling is her belly filled with eggs! (PC: Casey C.)

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Watch me stretch! (PC: Casey C.)

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Fresh out of the water! Can you see me? (PC: Casey C.)

Next week’s lab we are looking into what really determines the survival of these invasive species, so stay tuned…

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