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Friday, October 3, 2014

Cordell Bank: Northern East Ridge

After waiting it out at the beginning of the week, the forecast quieted down for several days starting Thursday, so that was the day that we targeted to move the boat.  Jim and crew managed to get the boat up to Bodega Bay by early afternoon, which is always a good sign.  We headed up after work, and this year we managed to avoid terrible traffic on 19th Ave and make pretty decent time, so we got to the housing enclave around 9.  So this meant I should be able to get a full night's sleep before the 6:30 boat meet time.  In theory anyway.  But in fact, I slept terribly, in part because I tried to go to sleep too early, before I was actually tired, but mostly because I was too excited about the trip!

So the result of that was that I felt not that great on the boat ride out.  I felt a bit queasy though there was absolutely no reason for the conditions to cause that.  Rob claimed that the mixed swell caused some swirliness, but from my perspective, it was flat flat flat.  The swell was practically non-existent, and there was a little wind for part of the trip, as in, a little wind so the water wasn't glassy like it was for the rest of the trip.  It actually seemed to get calmer once we got out a bit further, so when we arrived at the bank, it was back to glassy calm.

We had committed to spending one day to work on a little science project that was suggested by scientists at the sanctuary, so we did this on the first day (to make sure we would get it done).  The proposed project is a multi-year study using photos of meter-square patches along a transect line, which can be compared from year to year.  This requires defining a fixed transect that can be located repeatably from year to year.  After discussing a variety of ways to do this, we decided to leave weighted markers that would define the corners of a triangle, and run transect lines between the markers, and run along those transect lines to collect photos.  The lines are not permanent, but installed on the markers the day that the photos are collected, and then removed.  We did some practice dives using this technique, and had found that finding a good place to define the transect was really key, so for this year, we focused on defining the transect, installing the markers, and documenting the location of the transect.  Getting some photos along a transect line (on one edge of the triangle) was a possible bonus goal.  This allowed us to spend an entire dive scouting for a good site for the transect, if we had to.

So, we parceled out the tasks among the 6 divers (that were effectively diving in 3 teams of 2, though two of the teams deployed and deco'd as one team).  The main tasks included:
  • Scouting for the site and laying line from the downline to the site, and to define the bounds of the transect.  
  • Moving three weighted markers (on lift bags) to the site and marking the corners of the transect.  
  • Collecting video documentation of the site layout.
  • Getting a GPS mark for the transect (by shooting a bag that the boat crew would take a GPS mark of).
  • Optionally running the transect tape between two of the balls
  • Optionally, photographing a meter-square quadrat along the tape.
Kevin and I were paired up for the video documentation part.  In addition to documenting the site, we wanted to document the process of setting up the transect too.  Kevin was toting a giant HMI light (which Halcyon graciously loaned to us for the project), and would be lighting the scene while I video'd.  This was the first time we had used the HMI light, since there was only a small window of time that the light was available to borrow.  Rob and Matt were paired up to do the scouting of the site, and the four of us got into the water first, and then John and Clinton got in about 10 minutes later, so that once the line had been run to define the transect, they would be ready to go with moving the balls.

When we got in the water, we found that viz was quite good near the surface.  We passed a murky layer from about 20', though it opened up a bit deeper and then really close to the bottom it opened up even more, so that viz was really good on the bottom, but it was kind of dark and green.  Not night dark, but not bright blue water.  But I was very happy with the viz at the bottom; it would be much easier to get the work done with good viz!  There was some strange swirly mixing of water masses going on right on the bottom, though, where rather warm (high 50s) water mixed with the colder (around 50 degrees) water.  The interface between these two masses of water had that shimmery thing that did sort of obscure the visibility.  Also, I think that the warm water mass was not as clear.

We had hoped to be able to locate the transect near the man-made hole that we found on the reef last year, since that is a recognizable feature that we thought we could easily relocate.  As it turns out, the downline ended up right next to a man-made hole, though it wasn't the one that we saw last year.  We knew that there was a series of such holes, so we weren't that surprised, but the one we found last year had a metal pole "installed" in the sand, which wasn't there.  But still this was a convenient landmark that would help us to relocate our markers in the future.  Once we got to the bottom and got our bearings, we got right to work.  

There was quite a lot of current on the bottom.  So much current, that getting my hero cam out and setting it up on my scooter (which required going off of the trigger) without getting separated from the team was sort of a chore.  The current was really strong right on the bottom, but just a few feet above the reef, it calmed down.  Also, if you dropped down the side of the ridge, it calmed down there too.  The problem was, in order to get a good view of the reef for the video, I had to be on its level, so I was right in the current for much of the dive.  The HMI light worked great, though it was pretty challenging for me and Kevin to keep ourselves lined up properly (he was above me), since I had to be on the trigger for most of the time that I was video'ing.  It would have been much easier if I was swimming, since I could more easily fine-tune my pace as we were moving along the transect lines.  Still, I think we did a fine job of documenting both the site and the setup process.

There wasn't a huge amount of time for critter peeping, but we found a few things of note.  First, there was a brown Irish lord like right next to one of the marker weights that we set.  I can't believe he didn't just get up and leave when we placed the marker!  Also, I found a pair of painted greenlings doing their mating dance (and got some so-so video of it).  There were also quite a few small (some very small) lingcod.  This is interesting, since last year we noted an absence of "big fish" like lings.  But there are a ton of young ones now.  There was also a big school of widow rockfish hanging around above the ridge.  But the main thing about this site is the spectacular invertebrate cover.  It is just so colorful and so heavily encrusted with all kinds of invertebrates.  It looks exactly as I remembered it from last year, from one particular picture that Rob took, which is just so dang colorful.

In the end, we started to run one of the transect tapes, then decided we would not be able to get a good run of photos along it, so we pulled it and just got some general pictures of the area for the last few minutes.  Then Rob and Matt pulled the line while Clinton and John put the bag up for the boat to get GPS numbers.  Once we were finished cleaning up the line, we thumbed the dive too, and the four of us deco'd together.  Deco was pretty uneventful.  A few deco critters did swim by, and we tried to get some pictures or video of a few of them.  The layer that we had encountered on the way down didn't seem quite as thick on the way back up.

We surfaced to conditions that were just as flat as when we got in, maybe even a bit flatter.  It was an excellent return to Cordell.  Great viz, at a great dive site, though the conditions were a bit more challenging than last year.  And it was sort of a relief to be finished with the "work" part of the trip… we were all glad that we accomplished our main goal of setting up the transect, and we look forward to going back next year to see if the markers stay put!

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