Catalina Island

by Caitlin Contag
Originally published at ScientificAmerican.com

Today was my first scientific dive. There is no activity that I’ve done that requires more group work and collaboration than laying a transect tape and taking a species count. Not only do we contend with bulky gear and unwieldy tools, but also with limited ability to communicate underwater.

When a partner takes off in the wrong direction, no amount of banging on the tank and ambiguous hand gestures can assure that you will get him back on track. When we crossed several other groups’ transects and ended up in a thicket of giant kelp, I just smiled through my regulator and went with it.

Seagrass. Photo by Jim Haw.

We were instructed to do an invertebrate and sea grass count as a sort of baseline for Fisherman’s Cove, where we dive on Catalina Island in California. After a dry “rehearsal” on the helipad before actually gearing up, teams of four divers jumped in the water with two slates, a quadrat and a transect.

A quadrat is made of plastic tubing fixed into a square with rows and columns of string stretched across the square to make cells for a species count. Two divers swim out 100 meters with the transect tape and then secure the tape with a weight. They then swim back to the divers waiting at the other end, taking species counts every 20 meters.

Students collect data on seagrass density using quadrats placed along a 100 meter transect tape at specified intervals. Photo by Jim Haw.

Our dive began very auspiciously when a gigantic bat ray swam right past us through a huge school of fish. The visibility was the best it’s ever been for us, and the swim out with the transect tape was beautiful. Several times, I forgot that I was supposed to be working and stopped to stare at some particularly awesome creatures.

There were a dozen mating sea hares — huge hermaphroditic gastropods that lay eggs that look like spaghetti. A brown sea slug with electric blue stripes crept along one side of our transect tape. Tiny orange and red worms stuck out of the sand and countless lobsters poked their antennae out of rocks. It seemed like every single surface was covered in life.

As I hovered in the water column in awe, I was reminded of a conversation I had with one of our SCUBA instructors, Lorraine. When Lorraine and I spoke on one of the boat rides from Los Angeles to Catalina, she told me that she had been diving for a number of decades, and has dived many of the same sites thousands of times.

“You may look around and say, that’s a lot of fish,” she said, “but I look around and ask, where are all of the fish?”

My baseline of a dive site is completely different from someone who has dived the same site continuously for a number of years. To me, a site can look healthy and productive, but to Lorraine the same site appears relatively barren. Lorraine reminded me of the importance of our work — the populations we tracked today will vary over time. It is impossible to know that a system has changed without tracking the system. And without knowing that a change occurred, it is impossible to find the root cause of the transformation.

My baseline is from a period of a few weeks where not much change has occurred. I thought it was pretty cool when found one of the indicator organisms we were tracking today. But much of the recording matrix was filled with zeros. What would my slate have looked like if we had laid the transect in Fisherman’s Cove ten years ago? Twenty years ago? How has the creation of this marine protected area changed the biodiversity of this site?

All of these exercises are practice for our work in Guam and Palau, which are both poised to undergo drastic change as a result of human activity. For me, it isn’t enough go for a few fun dives in these tenuous sites. Coral reefs make me ache to gather the data necessary to protect their fragile ecosystems.

Caitlin Contag is a senior working toward a bachelor’s degree in public policy, management and planning at USC School of Policy, Planning, and Development. She is recording her experiences on Catalina Island and in Guam and Palau on her blog Avoiding Narcosis.

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One Response to Catalina Island

  1. Derek Lazo says:

    Caitlin this is AWESOME. You got on Scientific American! Anyways, the trip looks awesome so far, make sure you post some pics on your other blog when you dive around Apra Harbor

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