The Intruders Under Our Docks

A typical grey autumn day in Coal Harbour. Photo credit: Nicole Kellough

A typical grey autumn day in Coal Harbour. Photo credit: Nicole Kellough

Who would have known that the dilapidated docks flanking our local shores where home to numerous invertebrate species? Not only do these shores house these species, but their communities are thriving as we speak. As we build up and out into the ocean’s intertidal regions, these species continue to flourish on all our man-made structures. Viewing a whole community of species co-inhabiting the underside of the rock is easy – all it takes is a quick look down.

The expansive high traffic boat zones tend to be quite susceptible to invasive species – especially with million dollar yachts motoring into the harbours. Some of these are loaded with little critters stuck to the hull, which deposit themselves into the area once the boats are moored. If the conditions are right –I’d prefer sunny and warm with plenty of food –these invasive species can take over –just like us northerners flocking to Hawaii and Mexico. Due to the known tunicate colony, Botryllus schlosseri, which has invaded the docks of the Coal Harbour we decided to go on a field trip to determine their impact on the native species in the area.

MacGyvering the metre sticks! Photo credit: Nicole Kellough

MacGyvering the metre sticks! Photo credit: Nicole Kellough

Our expedition to the Royal Vancouver Yacht Club in Coal Harbour took place on a classic Vancouver autumn day, overcast and grey. As everyone was in such a hurry to load up the vans and get to the docks, we forgot the buckets for collections and the tape measures back in the lab. Not a problem for us! We all brought out our inner “MacGyver” and found sticks to measure out a metre using an 8.5″x11″ standard notebook. We also took some of the dog poo bags from in the park to put our collections in for transport  back to the lab. After a bit of a disorganized start we finally got on track and hit the docks for observations!

The large group split up into pairs and randomly chose shaded or lit 1-metre area with an objective of determining species richness in the presence or absence of non-native tunicate colonies. The number of species observed was marked down according to the presence of the colonial orange blobs and in conjunction with whether or not they were hidden from the sun.

The collection tub: two opalescent nudibranchs sitting on a hydrozoan. Photo credit: Nicole Kellough

The collection tub: two opalescent nudibranchs sitting on a hydrozoan. Photo credit: Nicole Kellough

In addition to observing numerous species, a few were collected and brought back with us to the lab. Two opalescent nudibranchs were collected along with an unknown nudibranch individual. Possible new discovery?! An anemone, some hydras, and mussels were also collected.

Since very few tunicates were collectively seen, our results didn’t show any relationships between the number of tunicate colonies and species richness. Further, there wasn’t much of a relationship between number of species in light or dark habitats. Further exploration on other docks may be needed to increase our data for a more significant statistical analysis –back to the docks we go!

If our experiments at the docks have spiked your interested in how invasive marine species get around and how the Canadian government is dealing with them you can go to the following links for more information.

Fisheries and Oceans Canada:

http://www.dfo-mpo.gc.ca/science/publications/article/2011/01-05-11-eng.html

Canadian Aquatic Invasive Species Network:

http://www.caisn.ca/en/index.php

“Mussel-infested Boat” News Article:

http://www.pentictonwesternnews.com/news/278730061.html

Just remember that prevention is easier than the clean up!

Don't fall in! Photo credit: Roma Nagin

Don’t fall in! Photo credit: Roma Nagin

 

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