Dive_Blog_2024_12_11_SSS1

Purpose: Watching El Nino Underwater TLC and sensor recovery and deployment.

December 11, 2024

By: William Hagey

Here’s the video made of our dive:

Here’s the video made from the time-lapse images:

Point Loma – SSS1

Vessels: The Celtic Knot

Topside Support: None

Divers: William Hagey, Paul Rahilly, and Jim Melrod.

Surface conditions: Calm 2 long period ~ 2 foot swells. High thin clouds, becoming sunny.

Visibility: 20 ft with some swell stirring things on the bottom

Temperature: 53° F

Current: Very mild.

Dive: Time in: 11:40 pm, Dive length 43 minutes

Depth max: 58 ft

Purpose: Deploy and Recover TLCs – and do a video transect.

Summary: There was as much or more kelp as before. We took a while to find the wreckage. We swapped out the TLCs, did a video transect, shot video and Jim took stills.

Equipment Notes: TLC NOAA13  with MintDOT551219 were recovered. Both collected full sets of data. The battery for the UVC LED and the salve LED light was 14.8V at 5AH made with two batteries that were diode-OR’d together. The UV-C light aimed at its window with a duty cycle of 30 seconds every 6 hours. The window on the camera was free of biofouling; the UV-C light seems to be working for this. The encapsulation of the UV-C light in urethane, WC-575, worked well.

There was plenty of algae growing around it but, not so much blocking the camera, thank goodness. The camera was tilted higher again so I hope to get a better video like the one we made from the data from early June to early August.

We deployed PMRG1 with Mini DOT 697549. Itt had not been badly corroded in its last deployment. (This unit has the first underwater cabling and so maybe the later systems have some electrolysis issues.) As a result, I did not encapsulate it. Instead I only changed the zinc for a larger one in hopes that it will hold up for two deployments.

Habitat characteristics and surveys:

The kelp bed is back again here and seems to be about the same, probably just maturing. This site has gone through dramatic changes in the past few months! It is looking more like it did a couple of years ago. I have now seen this site go from a mature macrocystis kelp forest back in 2014 when we first discovered it, to a wasteland after the 2015/16 El Nino event, to a place where the kelp came back, then to a ghost town again, and now back to a kelp bed. Maybe with our work in this project we will get a better insight into this.

At this point there is plenty of upper and lower story algae,macrocystis and Pelagophycus (elk kelp). There is also a lot of lower story brown and leafy red algae, including Laminaria and Desmarestia. W Hagey got video with his GoPro and Jim took stills.

Methods: I believe we have a good anti fouling solution with the UV-C lights going on for 30 seconds every 12 hours. We increased the rate to every 6 hours because we have the battery life, but I don’t think we need it this often.

Abalone: The star of this location is a large, about 9” red abalone. There are also many large reds in the wreckage. I didn’t look for the pink or pinto that are also nearby, because we were low on time.

Dive Details: We used the coordinates and landed about 12 meters east of the wreckage. It took us a couple swims in the wrong directions before we finally found it. This cost a lot of bottom-time. Once we found the wreckage we swam down the channel that extends from behind the wreckage at about 135 degrees magnetic. The TLC was about 42 meters in that direction. This has become our transect. I recorded video going both directions. Jim helped reel in the transect tape. This was very helpful. He reeled it up to the  first tape. I helped at that point and in the process left the TLC there. Not until I was at the anchor line did I realize it was missing. I swam back to get it. I used up my air. We will need to get better at finding this spot.

This is the Oxygen and temperature log for this deployment.

Above are four images from the previous four deployments. The camera is tilted so that one can see the background and kelp in three of the four deployments. I made sure that it had a good angle in the current deployment as well. Part of the problem may be that the camera is in a channel with sediment, not rock, below it and so it may settle in a little.

These are the abalone shells we found. Left to right, Red ab, 180mm (7 inches), Red ab59mm (1.3 inches) and a Pink ab, 120mm (4.7inches). Notice the small holes in the shell of the red abalone. These were caused by the same boring sponge that is living in the abalone in the time-lapse images. By the way, that abalone is a Red abalone and is about 230mm (9 inches).

Somehow this brittle star was living on the oxygen sensor. This is in spite of the fact that a copper plate covers much of the front of the sensor and a copper mesh covers the sensor.