The adventure begins…
Our group crept down the dock ramp single file, with a sense of anticipation hanging in the air. We had just gained access to one of the most notorious secretive lairs in Vancouver: The Royal Vancouver Yacht Club in Coal Harbour.
I nervously scanned the docks ahead, knowing our invasive foe was somewhere amongst the million dollar boats in front of me. The hunt was on. What were we searching for? We were here to hunt down Botryllus schlosseri, or the golden star tunicate.
What is a tunicate?
Tunicates are small filter feeding organisms that generally are found attached to rocks or other hard surfaces in the ocean. They are in a subphylum of chordates (organisms with spinal chords), called Urochordata due to their larval stages exhibiting most of the characteristics of a chordate. Some tunicates attach themselves to surfaces as individuals, while others live as individual ‘zooids’ in colonies.
The golden star tunicate
Golden star tunicates are colony tunicates that are native to the northeast Atlantic and Mediterranean, where they are commonly found as part of ‘fouling communities’ on dock pilings, rocks and boats. In the past century, however, their range has expanded globally primarily due to movement of marine vessels and fishing gear. They are considered an invasive species in Canada where they can outcompete or smother native organisms. One method to halt or slow their spread in some areas is to simply remove colonies before they reproduce. We were searching the docks of Coal Harbour to find golden star tunicates in an attempt to look at factors that may affect their abundance.
[Learn more about golden star tunicates in Canada here]
We explored down the docks, attempting to blend in with the wealthy club members, stopping every so often to peer into the murky waters below in hopes of finding our elusive prey. “There’s one over here!” I heard someone shout from down the dock.
My heart began to race. I walked over to find my comrades crowded around a barge, pointing down into the water. There it was in front of us, a colony of golden star tunicates. We had finally found our elusive adversary.
The journey concludes
We only ended up spotting a few more small colonies of golden star tunicates at the Yacht Club in Coal Harbour. As we headed back up the dock ramp, I couldn’t help feeling slightly glad we didn’t find more than we did. I had entered this journey expecting to be horrified by the abundance of this invasive species on the docks of Coal Harbour, but ended the journey happy to have mostly seen native fouling communities relatively undisturbed by the invasive tunicate.