Sunday, June 25, 2017

Arts and crafts

"I craft a lot, ok?!" Nicole exclaimed.

Nicole and Meghan, two summer interns at WHOI, helping
me make hydroid mimics.
Meghan and I burst into laughter. The three of us were crammed into my office, surrounded by plastic mesh and elastic cord. Nicole was threading the cord through the mesh in immaculate patterns - not a stray strand anywhere - almost like cross-stitch. It was impressive. The task required a lot of dexterity, and our afternoon ended up feeling like an arts and crafts class. The three of us spent hours carefully threading stretchy strings through tiny holes, making what looked like tufts of synthetic hair. Trust me, friends, it was for science.

You see, one of my sites for the succession study is dominated by hydroids. They showed up in droves and have grown to cover almost all of the available space. One of my questions for the succession study is how the first species to settle and dominate a substratum influences the development of the community, and the hydroids are obviously an important group. There is lower diversity at the hydroid-dominated site than at my other site in Eel Pond, so I want to figure out how the hydroids are affecting the organisms around them.

I expect a couple of things could be going on. First, the hydroids could be actively consuming larvae of other species and preventing them from settling or just eating all the food there is. If that's the case, I should see lower recruitment of benthic invertebrates on panels with live hydroids. However, the hyrdoids could just be passively preventing other organisms from settling by blocking their particulate food from reaching the panel or by occupying space. To see which one of these scenarios is true, I had to build structures that were exactly like hydroids but non-living.

A fouling panel with hydroid mimics (left) and
live hydroids (right)
Enter the elastic cord and plastic mesh.

Using fouling panels that had already been colonized by hydroids, Nicole and I set up an experiment this weekend. Some of the plates were "live hydroid" treatments and remained largely as-is. Other plates had their hyrdoids removed and replaced with synthetic mimics. We also had a "mesh only" treatment and a control with no inhabitants.

I'm very curious to see what recruits to the different types of panels. I suspect the hydroids have a significant effect on their community, so I should see some differences between the treatments. We'll check back later in the summer to see!

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