Sponge Bioherm in Howe Sound aka Sponge Bob 27/05/2012

Jim Dixon and I had a chance to re-visit the sponge bioherm that we were supposed to do as our first tech dive after finishing GUE Tech 1. We were pretty exited to see what we missed the first time around! I found a link to some material on the sponge bioherm here. Looks like it is the only sponge reef in Howe Sound. Pretty interesting!

http://www.ualberta.ca/~jwchu1/

I had seen glass sponges a lot, but did not realize that they could form reef structures like that. There is some video on that site as well. The Vancouver Aquarium is monitoring this bioherm too.

For the Topline, it had become a very popular dive site. They had nick-named it "Sponge Bob". It was a tricky site to dive, since it was in the middle of Howe Sound a bit south east of Halket bay. There was no mooring line, and you had to find it with GPS and depth soundings. Currents were a problem, and the tides had to be right for it to be dive-able. The reef started at about 70 feet, and went well below 150 feet. The usual plan for the Topline was to drop a shot-line to give some visual reference on the way down. If you didn't, it would be very likely that the current would blow you off of the reef and you'd totally miss it.With the deep waters in the area, it would make for a disorientating blue-water dive. You couldn't hang on to the line either, as it was not anchored like regular descent lines. Also, due to the fragile nature of the reef, everyone had to be very careful not to disturb anything. Buoyancy and propulsion control were key. This was not a dive for novices.

I was talking to Ken and on the last trip, someone grabbed the shot line and pulled it loose. That meant that the first group found the reef, but everyone else was blown off of it before they even saw it and totally missed it. It was very important not to touch the line!

Jim and I had a tech dive planned with an average depth of 45 meters for 30 minutes, and using 18/45 Trimix. 18/45 was just the tool to do such a long deep dive. That obligated us to 30 minutes of decompression, with an additional 5 minutes added in from 6 meters to the surface for added conservatism.

With the dive plan set, the Topline dropped the shot line and Mike Juren went in first to make sure it was relatively secure and to attach a strobe to the line. He sent up a marker buoy when all was well. That signaled the start of diving!

The first team of Alan and John went in, and then Jim and I. There was also Jason Kolba and Dave doing a recreational dive (and one other fellow whose name I keep forgetting!), along with another group of divers up from the US I think.

Jim and I followed the line down, and the reef quickly loomed to meet us. The visibility was pretty good, and there was indeed some current but it wasn't too bad. I was leading the dive, and once we reset our timers and average depths at 70 feet, we continued on down. I took us north west-ish down to our planned depth and we followed that out to our turn time. The reef was not what you'd expect. It was like a big pile of mud or ooze pock-marked with large sponges. The really impressive sponges were around 40 meters. The bigger ones were at least the size of an easy chair. Some of the more impressive ones appeared to be "melting" like candle wax. I had never seen glass sponges like this before. I would say the glass sponges in Agamemnon Channel up by Egmont were a bit more prolific, but these made up for that in their Doctor-Seuss like shapes. We passed Alan and John during our dive as well. The visibility was good, and I always liked how it seemed like you were meeting astronauts in space when you came across another dive team. I got some video of the dive, and I hope it will give some sense of what we saw:



We found the up-line with no difficulty and our deco to the surface passed uneventfully. It was a pretty dull 30 minutes though! There was nothing but murky water to stare at, and the small up-line. Still, what we saw on the dive made up for that.

The next dive we did after a nice long surface interval was at a site called Stairway to Heaven. It was a wall on the back side of Bowen Island, and I had not dove there before. Jim and I took our remaining gas and planned a 20 minute dive to an average depth of 38 meters. We were putting what we learned in our GUE Tech 1 class to good use, planning the dive on the fly. The dive itself was nice, but nothing too memorable.

Back on the surface we headed home. The sponge dive was a success!