Dive Dry with Dr. Bill

#150: But It's So Dark Down There!

My nephew David's return to Catalina from Atlanta (after just a week's absence) offered some wonderful diving opportunities last week. He continued to bring good luck in the black sea bass arena. We had several long encounters (up to 22 minutes) with individuals and courting pairs as we dove in the dive park together. But today's column (the 150th in this series) will not focus on that. There was another dive experience I'd like to write about today. I did take David on his two deepest dives (80' out past the wrecks and 92' at the base of the Sujac) and he handled them like a pro, but those are also not today's subject. He was interested in trying one dive I rarely do here on Catalina... a night dive, and that is well worth discussing.

Now I love night diving in the tropics where the air and water are warm, and the sharks are often out to observe (we them and they us). However my last night dive in the dive park was Fourth of July last year when I tried to film the fireworks from underwater. Not a rousing success I might add. However, David really wanted to do one, and I've found two nice dive lights in the past year so I really needed to give them a test. We drove the jeep down to the park about 8:15 and suited up for the dive. I would take my video camera (on only its second night dive ever). Our dive plan was to stay close to shore and not go below 40 ft.

We got to the bottom after our buddy checks and descent, and I turned on my small dive light and clipped it to my BCD so it would always be available. David carried the other light in his hands. If all else failed, I also had my video camera light with a fully charged battery. Once our buoyancy had been established, I switched on the video light. It immediately bounced off several lobster, or they bounced back from its beam. This was no surprise since lobster generally feed under the cover of darkness. They'd be an easy target for black sea bass, sheephead or other predators if out in the open during the day. There were a number of lobster racing around the bottom, trying to get out of the light. They flapped their tails to jet propel themselves away, sometimes running into David in the process of escaping from me. To put it mildly, that didn't endear them to him (he'd much rather encounter them on a dinner plate at night... good thing they are out of season).

Seeing so many lobster was no surprise. Neither was the absence of the garibaldi's damsel fish relative, the blacksmith. Although these are very common during daylight, often feeding in large schools on the abundant plankton, they shelter at night to escape potential predators like sea lions and harbor seals. There were blacksmith sheltering everywhere we looked in rock crevices, under rocks and in small caves. When the light would shine on them, they'd often put their tails into overdrive seemingly in an attempt to propel themselves right into the rocks or bury themselves in the sand. It was interesting to note that a number of the blacksmith had lighter colored stripes running vertically on their bodies. Of interest ecologically is the fact that blacksmith are important in transporting nutrients for algal growth. They capture their planktonic food all day, then defecate when sheltering in the rocks at night. This provides significant nutrients (fertilizer) for algal growth.

Another fish that sheltered at night was the sheephead. We found several resting on the bottom, usually lying against a rock in a protected area. We encountered a few sheephead sleeping soundly until my video light caused them to awaken and escape. Their wrasse relatives in the tropics often shelter at night, with some species burying into the sand. Our own local senorita also goes "underground" as well, accounting for their absence on our night dive.

With predators like the sheephead sleeping soundly, urchins like the black (or Coronado) urchin come out of hiding in the rocks. With no fear of getting munched on for their caviar (a delicacy in Asian markets as well as for local fish), they are free to expose themselves and feed. Almost every black urchin we encountered was well out in the open, resting on a vertical rock surface near their shelter hole feeding on detritus and possibly plankton in the water column. When the video light struck them, they would seem to get agitated, and some started moving away. I didn't keep the light on them for any longer than necessary to avoid upsetting their internal "biological clocks." David could understand this due to the time difference he was experiencing here on the West Coast, and I could as well because my body is only used to being submerged during daylight!

With all the new behavior to film, I was totally absorbed in the dive. Of course I kept a good eye on David, who stayed close by like the good buddy he is. I didn't realize another reason he stayed so close. Since this was his first night dive, David was experiencing slight claustrophobia. This is not unusual when you are surrounded by pitch black (the nearly full moon had yet to rise) and can't orient on anything. And of course the mind often plays little tricks on you in the dark... you start hearing that music from "Jaws." Well, we didn't even see a horn shark on this dive but David did occasionally shine his dive light into the darkness of deeper water just to check! Wonder what we both would have done had we seen a big set of teeth heading our way? Probably added to the "fertilizer" the blacksmith were depositing!

We were underwater just over 30 minutes. I came back with a new appreciation for night diving in our local waters, and lots of ideas for new film subjects! David came back with some doubts about his future as a night diver, but glad he tried the experience. It truly is a different world underwater at night, and there is a lot of new biology I can learn by diving in the dark more frequently (and more video I can offer for my "Dive Dry..." viewers).

David is back in Atlanta with many great diving memories, so he cannot be my buddy for some time (undoubtedly a frequent event if he gets accepted at USC in a year). My son Kevin visited this weekend and has expressed interest in learning to dive! However, there is a new dive buddy of the female persuasion (my favorite persuasion of course) on the horizon. I'm not going to let the catfish out of the bag yet (have to protect this lovely woman's honor), but this particular lady diver will be coming out as my dive buddy in the future. I will say no more... yet. However, I'm already wondering if this new relationship will tilt the focus of my columns from mating to munching, or simply intensify the focus on the former! Time will tell... and maybe I'll tell in time. Keep tuning in to find out whether Dr. Bill's loose lips will sink ships or not. Of course we really don't need another wreck in the dive park.

© 2005 Dr. Bill Bushing. Watch the "Dive Dry with Dr. Bill" underwater videos on Catalina Cable TV channel 49, 10:00 AM and 5:00 PM weekdays. Buy my "Munching and Mating in the Macrocystis" DVD so you can take Dr. Bill home with you... we'll both be glad you did!

Out of season lobster ready for the dinner plate (in a few months), black urchin out in open feeding;
sheephead snoozing soundly; blacksmith fertilizing the algal crops.

This document maintained by Dr. Bill Bushing.
Material and images © 2005 Star Thrower Educational Multimedia