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2007/05/06

Diving at PLSR

I went diving yesterday at Point Lobos State Reserve. There were a few items I need to remember when I go there next.

1) PLSR doesn't open until 9:00am. We arrived at 8:40am and were the fouth in line to get in.

2) Whaler's Cove opens at 20° with a narrow mouth. Return path should stay more easterly lest we wind up on the rocks at the western point.


The first dive was to a maximum of 40 feet for 30 minutes. I started the dive with 2800 psi and finished with 900psi. The water was much colder than I would have expected (45°F/7°C at depth). We dropped in over the sand where the visibility both vertical and horizontal was about 1 foot. After making our way toward the kelp on a course of 30°, the visibility stretched out to 10 feet. The surge was strong but not unbearable.

The second dive was to a maximum of 28 feet for 36 minutes. I started the dive with 2800 psi and finished with 1300 psi. We used a 40° heading this time and found some nice kelp forests. After returning to our drop area, we practiced two skills (oral in flation of the BCD underwater and out-of-air, share-air). In the future, I will try to incorporate more of these refresher skills at the end of a dive.

Interesting things seen during the dives:
1) Floating "Man-o-war"-like jelly fish about 1 inch long with dark irridecent blue fringe on the sail and very small stub like tentacles on the bottom. These are known as By-The-Wind Sailors (Velella velella).

info
Biology/Natural History: This species is a puzzling one. It has long been regarded by many as a type of siphonophore; a pelagic colony of hydrozoan polyps similar to Physalia, the Portuguese man-of-war. Recent study suggests that, instead, it is a single very large hydrozoan polyp (Order Chondrophora), floating mouth downward and with a chitinous float and sail instead of a column. If so, it is an extremely large polyp for a hydrozoan. At any rate, the underside also includes many small polyps that bud off small medusae. The medusae (up to 1.5 mm tall) sink to as far as 2000m depth and produce gametes. The developing embryos develop floats and rise back to the surface. This species is oceanic, being usually found far offshore. The angled sail makes it sail at 45 degrees from the prevailing wind. Some have a sail angled to the left, others to the right. Off California the right-angled form prevails, and these remain offshore in the prevailing northerly winds. Strong southerly or westerly winds, however, may bring huge aggregations ashore. Velella have symbiotic algae (zooxanthellae) in their tissues, and also feed on zooplankton. They are eaten by pelagic gastropods such as some nudibranchs and bubble-rafting snails. The pelagic gooseneck barnacle Lepas anatifera occasionally attaches to the dead chitinous floats. This species has many nematocysts and a few people have reported feeling a sting, but I have handled many and have never been stung even slightly. The species feeds on fish eggs and crustacean larvae.

2) Cryptochitons, bat stars, lingcod, surf perch, etc.

Here are a couple of videos from this dive:
http://www.youtube.com/watch?v=Ncrpwsz_cQc
http://www.youtube.com/watch?v=kaQDYB4zxso

Posted at 05/06/07 on 2007/05/06 by Stephen - Category: Northern California Diving -
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