Catalina Chronicles Pt 3

2/12/2017
Catalina Island, California
 
After three and half days of diving and living on Catalina Island, we were finally ready to start wrapping things up. The weather finally cleared and on Sunday morning we greeted by bright, beautiful sunshine. Although we had accomplished quite a lot over the weekend, we had one last experiment to conduct before we could pull the chambers and break down our gear. While the dissolved oxygen sensors left inside the chambers gives us an understanding of what the community of algae is doing over a 24-hour cycle, Genoa also needs to know what the individual species are contributing. And by contributing, I mean how much oxygen they can produce via photosynthesis versus how much they can consume via respiration. In other words, what is going on during the day (photosynthesis) and what’s going on at night (respiration). Just like our own cells, plants and algae also respire, consuming oxygen as a form of cellular metabolism. 

Cold water is giving giant kelp a chance to out compete Sargassum

Genoa changing a light filter

Close-up of Sargassum in the photosynthesis vs. irradiance experiment

​In order to do this Genoa (Tristin, and I) conduct lab experiments that help us generate photosynthesis vs irradiance curves. Irradiance is a measure of light; we expose algae to different light levels, from total darkness to full irradiance, and measure the amount of dissolved oxygen either produced or consumed. Once we get the data we can plot it as a curve, a P vs. I curve, which helps us visualize the relationship between light and dark, and oxygen consumed versus produced. We can then couple that with the data from the surveys in Genoa’s plots, which gives us a nice pairing of field and laboratory data.
 
Genoa also does incubations in the field with blades of giant kelp; because giant kelp blades are so big it’s more efficient to measure their productivity directly rather than generating a P vs. I curve. These kinds of “in situ” measurements give us a really good understanding of what giant kelp is doing in its natural environment.

​ All in all, we had a really successful field trip. It’s no easy feat to try and do a whole season’s worth of data collection in three and a half days. But this is what ecologist’s dreams are made of. Sunburnt and tired, we had a two-hour ferry ride back to San Pedro, and another two-hour car ride back to San Diego. On Monday morning it was back to business as usual.




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Thanks for reading about our Catalina Chronicles! Be sure to check back in as the spring semester develops.
 
Cheers,
 
-Baron von Urchin

Sunday morning brunch on the dive boat

Sunset on Catalina Island