Dive_Blog_2024_12_11_PL4

Purpose: Watching El Nino Underwater, Swapping of TLCs

December 11, 2024

By: William Hagey

Here’s a video of our dive:

Here’s the video made from the time-lapse camera from the past two months:

Point Loma – PL4

Vessels: The Celtic Knot

Divers: William Hagey, Paul Rahilly, and Jim Melrod

Topside Support: None

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

Visibility: 25 ft

Water Temperature: 53° F

Current: Light current at the surface and at the bottom

Dive: Time in: 9:43AM, Dive length 42

Depth Max: 72 ft

Purpose: Swap out TLCs, Video transect. (The transect was done to and from the end of the lead-line with their Mini DOT and video was recorded around the site.)

Summary: The TLC and Mini DOT were replaced with new units. Video and stills were taken by W Hagey with new GoPro 12. Jim Melrod took stills and Paul had his competent watchful eye on both of us.

Equipment Notes: We recovered TLC NOAA13 with O2 logger SN799870. It had not moved during the deployment. It had additional 5 and 3 pound dive weights added. It was still taking pictures with the slave still working and no biofouling on the front window of the camera. This is evidence that the UV-C light is protecting the window. The UV-C light had it’s exposed aluminum parts potted in urethane, WC-575, and this protected it from corrosion. I was still surprised to see how much the zinc was corroded on the 316 stainless steel parts. The slave light and UVC lights were still working with plenty of extra battery life. (The slave and UV light pack had 5 AH at 14.8V (two battery packs diode ORed together. This was plenty of power.)

PMRG 3 with Mini DOT 76000 was deployed with the UV-C light. Since it had not been badly corroded (This unit has the first underwater cabling and so maybe the later systems have some electrolysis issues.)  A 5-pound bright yellow dive weight and 3 three pound weights were added to the bottom of the TLC as additional anchoring in case a large swell rolls through in the coming months.

Habitat characteristics and surveys: The kelp is back at this site. I didn’t more than last visit, two months ago. The bottom is hardscape with pits and a gentle slope. There is upper and lower story macroalga. This location is well known since it has been a release site.

Methods: We dropped anchor at the far end of the lead line near their Min DOT and swam our transect along the lead line to and from the TLC. I also video recorded the area in front of the TLC like last time. There was plenty of time to swap out the TLCs. I took plenty of video with my GoPro 12 and stills with my Minolta, and Jim took stills with his new strobes. A 50 meter transect was not run but I did record video of the area and on the way back from the TLC to the anchor.

Abalone: We were so focused on our task, so we didn’t look around for abalone.

Dive comments: We were able to hold position with in a couple of meters as we dropped anchor with the result of a perfect starting point. The water was pretty clear.

This is the oxygen and temperature profile from this deployment

See photos below:

Diamond turbot (Hypsopsetta guttulata)

The upper image is from the newly recovered TLC and the image below is from the TLC that was recovered in August. Note, good and similar alignment.