Dive Dry with Dr. Bill

#448: Trekkers... In Another Dimension

My friend Rod Roddenberry has taken his father Gene's Star Trek philosophy into the sea. Now you, too, have a chance to experience "trekking" in this new dimension. Most of our island residents and many of our visitors have heard of the new attraction known as Sea Trek offered by the Santa Catalina Island Company and Catalina SCUBA Luv. Several have expressed concern to me about the impact of people walking on the bottom in helmets that look like they come from an astronaut's closet. In previous columns I have addressed these concerns with my belief, based on 42 years of experience here, that the sand stirred up by the Sea Trek participants would be minor relative to Mother Nature's own influence; and that sandy bottom habitats are highly dynamic ones and the critters who reside in them have evolved mechanisms to deal with the frequent ecological "disturbance" of waves, swell and surge.

I stated this in a letter of support sent to the Coastal Commission last year. They decided to impose several restrictions on the Sea Trek operation, including a scientific program to monitor the possible impacts from Sea Trek and compare them with natural causes of disturbance. It is always a good idea to base decisions on objective scientific data rather than someone's anecdotal observations (even if that someone is me!). The monitoring contract went to Coastal Resources Management Inc. in Corona del Mar. Rick Ware designed the experiment to determine the extent of these potential impacts, and I was asked to be the on-the-scenes guy to implement the water sampling and other day-to-day aspects of the monitoring program.

Rick designed the experiment to evaluate the level of turbidity in the waters of Descanso Bay. Turbidity is defined as the optical clarity of water. Clear water will pass light through it in a nearly straight line. Turbid water has particles in it that scatter the light, and reduce the amount of it transmitted to depth. Turbidity can be caused by natural elements such as plankton or sediments that are resuspended by wave action, surge, marine animals and, possibly, Sea Trekkers. It can also measure the impact of certain pathogens and pollutants, although this is not a concern in Descanso Bay.

Rick established two primary scientific tools to conduct this. The first is a series of seven pairs of submerged light detectors near the bottom and three individual sensors located near the surface. These will record light levels near the surface and near the bottom to detect what percentage is being scattered by particles in the water. The second tool is a daily sampling of water from about one yard (1 m) off the bottom near the submerged light sensors. Sites are established so that some are in areas close to the Sea Trek walkway, while others are located pretty far from it and serve as controls over the sandy bottom and near the kelp beds.

My role is to collect the water samples using a van Dorn bottle deployed from a skiff. The van Dorn bottle is lowered fully open to a point about one yard from the bottom. Then I send a "messenger" (heavy section of pipe) down the line to trigger the bottle's closing mechanism. The sample is then brought to the surface in the sealed bottle, placed in the appropriate sample bottle and tested for turbidity three times when I get back to "Doc's Lab" (my kitchen). The other function I perform is to dive every third day to locate and clean the light sensors. If this is not done, natural bacteria and tiny algae may grow on the sensor and reduce the amount of light that reaches each one, thus skewing the data. I am looking forward to the analysis of the 294 turbidity measurements I made in the first round (May) to see what the actual scientific data reveal. I have a lot of faith that the naturally high turbidity of Descanso will not reveal much effect from Sea Trek, but the proof will be in the data.

We will run these tests for 14 straight days in May, July and September to look at any changes over the course of the summer. I had suggested this to Mayor Bob since readings from a single period of time may not reflect changes that occur naturally in the marine environment. So far May has given validity to that suggestion. Not only did we have unusually high turbidity due to wind, waves and surge... but it is also the start of "bat ray season" which I've described previously. When these winged fish "munch," they hammer the bottom to stir up sediment and uncover delectable morsels... like worms (yeck).

My dives to locate the submerged sensors in May were never been completely successful. On most sampling days s the bat rays had so disturbed the site that visibility plummeted to as little as zero, and I was not about to feel around blindly when the rays... and their stingers... were all around me. No desire to get Steve Irwinized during this project! On my best dives I managed to find five of the six pairs of sensors, but the sixth eluded me on every dive and wasn't located until the last day despite the fact I searched and searched. I thought a bat ray, or a boat anchor, might have carried it away.

At one point on a dive the visibility was about 3 feet due to these critters and the surge. I looked out into the murk and thought I saw a 12 foot great white shark coming towards me. I could only make out a dim shape moving in my direction. Gulp,. In a few nannoseconds I was relieved when the shape came into focus about 2-3 from me... and it was a pair of giant sea bass swimming head to tail fin that were coming over to check this "bubble breather" out! Imagine the Trekker on their first submergence seeing these magnificent fish up close and personal! What a treat.

Last Sunday I completed the first dive in the July monitoring period. What a difference! I could probably see close to 50 ft and the only light sensor I couldn't find was one hidden in the shadow of a large sailboat moored above. The chains holding the sensor above the bottom had been separated by the sand line from the mooring, so I had to do a little repair work. What a beautiful dive though. So nice to have great visibility. Unfortunately that also allowed me to find a dead sea lion on the ocean floor. I think it is the same one that was sick on Descanso Beach a day or two before.

Sea Trek has reminded me of some of my early "diving" back in the 60s. I was a lifeguard in a large Chicago area pool with a deep diving well. Every day we had to place a 75 lb. brass dive helmet on our heads, stick a hookah hose in our mouths and vacuum the leaves and dirt off the bottom of the pool's well. Of course visibility there was FAR better than what I've experienced recently... and there were no sharks or sea bass in those waters, only lovely mermaids in bikinis swimming above me.

NOTE: While carrying my gear for this project from my house to Scuba Luv to the skiff tied up at the Pleasure Pier, a small white bag containing both my dive computers, a compass and other dive "stuff" disappeared into thin air. I'm hoping an honest individual picked it up thinking someone had left it behind. My business cards were inside so they can easily find me. However, if a man or woman opens their trench coat in front of you and you see a pair of dive computers dangling inside, please call the police and let me know. I really don't like working for a week just to replace the two computers if someone walked off with them. This has left a really bad taste in my mouth... and it's not from my cooking!

© 2011 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 29, 10:00 AM weekdays and on Charter Communications Cable channel 33 at 7:30 PM on Tuesdays in the Riverside/Norco area. Please help me climb out of self-imposed poverty... buy my DVD's (see this link). Yes, take Dr. Bill home with you... we'll both be glad you did!

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My friends Joel and Jeanne enjoying Sea Trek last May, one of the underwater light sensors/data loggers
I clean every few days; Van Dorn water sampling bottle with weight and pipe "messenger," and LaMotte
turbidimeter used to measure the clarity of the water samples (alongside my dirty breakfast dishes).

This document maintained by Dr. Bill Bushing.
Material and images © 2011 Star Thrower Educational Multimedia