Go with the Flow: Little Isopods in Big Waves Part III

12x2x1 meters, 45,000 liters, a bag of pep-O-mint lifesavers and 12 big rocks: welcome to the flume. My research partner Sam and I met with the research coordinator on station yesterday regarding the use of the flume for part of our experiment. I’ve wanted to put something in the flume since I first came to Bamfield in 2011, unfortunately my research partners weren’t interested in biomechanics so we did a short behavioural experiment with decorator crabs. This summer I researched biotic influences on tide pool chemistry (see my posts on that project here: I & II), a topic which did not lend itself to flume research. But this fall worked our perfectly: our algae course measured drag on kelp in the flume and now Sam and I are going to use it for part of our research on Idotea (see parts I and II of our Idotea research)!

Top down view of the flume. It is currently divided in half to increase velocity, normally the centerpiece and wood pieces over the top aren’t there.

The flume is essentially a large rectangular glass box which creates laminar flow by recirculating water. You can change velocity, adjust temperature, use fresh or salt water and rig up all kinds of cool devices. It is equipped with a PIV laser which can be used to visualize flow around objects. Unfortunately we are unable to use the PIV system for our project due to time constraints and lack of training, but I was able to see it in action earlier this summer when an engineer was here looking at flow around tidal turbines.

Classmates Ondine, Angela and I in the flume ready for the PIV system to be turned on. You have to wear heavy duty goggles to block out the infrared light rays. Photo cred: Patrick Martone

We are going to measure flow over different morphologies of seaweeds on which Idotea are commonly found. We’ve chosen 2 seaweeds with very different morphologies: Fucus distichus is thick and highly branched while Ulva lactuca is a thin sheet. We have observed Idotea on both, but more commonly on Fucus at our exposed site and often under or on Ulva at our sheltered site.

Fucus disitichus; a thick, branched brown seaweed

Ulva lactuca; a thin, sheet-like green seaweed

Our plan is to find rocks with either Ulva or Fucus attached to them and tie lifesavers to the rocks so when put in flow the lifesavers sit in the middle of the seaweed. We’ll place them in the flume then compare how much mass the lifesavers have lost. We’ll also remove the Ulva and Fucus from the rocks and repeat the process. This will give us information about the amount of flow experienced by Idotea when they are on these seaweeds, giving us insight into their habitat preferences.

The glamorous side of science: the first bucket of rocks, the first flight of stairs

I picked up some pep-O-mint lifesavers (the industry standard, calibrated lifesaver that is used for mass dissolution projects similar to ours) in Nanaimo last month and we are finally going to use them this Sunday. I’m super excited to get this experiment going, we might have to trouble shoot a little as size and shape of rocks could affect flow, but hopefully we find some significant results!

One thought on “Go with the Flow: Little Isopods in Big Waves Part III

  1. Nice work Christina! What a great opportunity to use the flume. It sounds like you and Sam are going to be able to answer some pretty interesting questions about Idotea. It was really interesting in your presentation to see that the hooks on Idotea are more like little pinchers. Are these types of structures present in other isopods? Do they serve a similar function in other species? I have noticed that often large isopods (males?) will hold onto smaller isopods (female?) do they do this using the same hooked structures?

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s