When one thinks of fancy, exclusive yacht clubs, one doesn’t immediately think of unwanted and uninvited guests. Yet that was exactly what we were looking for on our recent trip down to the Royal Vancouver Yacht Club in Coal Harbour. And no, this wasn’t a journey of self-discovery – we were invited … this time.
We were on a search for invasive species living on the docks, piling and boat hulls of the marina, collectively called the fouling community. We were even looking for a specific unwanted guest, the golden star tunicate (Botryllus schlosseri). First off, what is an invasive species? I feel that if a concept can’t be explained in a cartoon, then it might not be worht reading about. So, to help explain what makes a species invasive, this cartoon:
You see, a new species has to arrive in a new location, establish a population, integrate into the community and then spread throughout the area, negatively impacting the area as it goes.
Second, what exactly is a golden star tunicate? Fortunately I had my camera with me and I was brave enough to submerge it (and my arm that was holding it) into the frigid fall waters of the North Pacific:
A tunicate is a type of invertebrate animal, part of the Chordata phylum, which includes all vertebrate animals – animals with a backbone, amongst other traits. In other words, our cousins, a few times removed. The golden star tunicate happens to be colonial, so that orange guy beside is a bunch of clones of the same individual, and can live for several decades.
The golden star tunicate was reported several years ago and we wanted to find out 1) if there are more tunicates in bright areas with greater sun exposure, or if there are higher numbers of different native species in those bright areas with greater sun exposure, compared to shady areas? 2) Does the total number of tunicates found at the marina depend on how salty the water is that year? The yacht club is not far from the mouth of the Fraser river and in wet years, the river can add a lot of fresh water to the surrounding inlets. 3) Is there a relationship between the amount of tunicates present and the number of different native species in the community?
To answer these questions, we randomly surveyed the fouling community in both sunny and shady areas, counted how many different native species were in a giving area, and how many golden star tunicates were in that area. The area surveyed was the standard measurement of one half of a BIOL 326 professor. As measuring tapes were forgotten, we estimated 1-meter sticks against our 2-meter professor, and counted underneath the sticks. One mustn’t let a memory lapse get in the way of science.
Sea stars and mussels, part of the fouling community. Photo credit: Jake Dytnerski
After analysing all of our collected data, I’m sorry to report that we were not able to conclusively answer our questions. This could be due to too few surveys done and too many beautiful boats looked at. After all, it’s science, and the answers are rarely clear.