Thursday, April 9, 2015

Precious sounds of life

"I lift my mind to the sky
And I let it take flight
The wind carries to my ears
Precious sounds of life
Soon I break all ties
Which bind me to this earth
All that surrounds me seems to melt
Into the blue eternal"
-"Higher" by Asgeir

When I left for Norway last August, the timing was actually less than ideal. I had been conducting an experiment off the Oregon coast that summer, and on the day I left for Norway, the experiment was not yet finished. I left detailed instructions and all the necessary supplies in the hands of a student I trusted, hoped for the best, and jetted off to my Norwegian adventure.

The Oregon coast and Cape Arago Lighthouse, seen from
R/V Pluteus
The experiment continued in my absence, lasting long into the fall. Unfortunately, by the time the experiment was finished and all equipment had to be returned to land, large autumn waves made it too dangerous to go out to sea. My equipment spent the winter offshore.

Caitlin and Zabrina, my two volunteer helpers for the day.
Thankfully, my equipment is nothing fancy or expensive, just cement blocks and acrylic settlement plates. The point of the experiment was to see how distance from a source population affects recruitment to isolated rocks, so I made fake rocks and planted them at different distances from a rocky reef, then went out every 3 weeks to see what had grown on them. The cement blocks got left at sea over winter, so today, I went out to see if I could find them. To be honest, I expected most, if not all, of the blocks to be long gone. The Oregon coast is exposed to powerful, downright nasty storms in winter, and it's perfectly conceivable that even my 100-pound cement blocks could be carried away by a strong current or intense wave action.

As we steamed out of Coos Bay and onto the open coast, two voluteers and I sat on the bow of OIMB's 42' research boat, the R/V Pluteus. The captain had agreed to drive past my study sites, slowing down as we passed each one, so that the volunteers and I could scan the sea surface for buoys. Our plan would have worked great, except that the waves today were big enough to render the bow a useless vantage point. There was so much salt spray, I could barely look up or open my eyes. Time to move to the stern.

A recovered cement block with acorn barnacles and anemones
When we found our first block, I almost didn't believe it. It wasn't until we had pulled up all 300 feet of rope and could see the cement block on the end that I believed the buoy was mine. A miracle! The block had survived the winter! Not only that, but it was covered in acorn barnacles and anemones. I had seen plenty of acorn barnacles last summer - they were one of the most common species on my settlement plates - but the juvenile recruits were always too small to properly identify. With larger barnacles now visible on the overwinter plates, I have a good shot at morphological identification. What precious, precious signs of life!
Metridium anemones on my mooring rope

The anemones, on the other hand, need no identification. I can tell you right away that they belong to the species Metridium senile, a common plumose anemone on the rocky reef. I had only rarely observed Metridium recruits on my settlement plates last summer, so it was interesting to see them on the cement blocks and attached ropes in quite high densities. I was especially impressed at Metridium's growth rate - it appears that a new recruit can grow from microscopic to several inches across in just 7 months or less.

A basket star wrapped around my mooring rope.
Our final find for the day was a basket star, Gorgonocephalus sp. Basket stars are famous predators, and they like to wrap their branched arms around corals, sea fans, or other upright animals on the rocky reef. When we pulled up one of the cement blocks, we found a basket star had wrapped itself around the mooring's rope. I can't say for sure how it got there - if it was a new recruit or if it had come from the rocky reef close by - but it was definitely a neat find.

Out of 8 cement blocks left out at sea, we were only able to find 2, but that's still 2 more than I ever thought we would find. In the end, we brought back some cool animals and valuable barnacle specimens. I call that a successful day.

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