Kelpscape

Bubbles

Two bubbles, at the top of a cloud of bubbles. Somewhere below me a diver exhaled. Bigger bubbles rise faster than smaller ones; they trail clouds of smaller bubbles that break from the edges and fall behind. Sometimes the big ones split in half.   It's a fun thing to watch, as a diver waits out a safety stop in open water.

Opalescent Nudibranch

Apparently, opalescence is a specific property of some semi-transparent materials. Light appears bluish when reflected at an angle from inside these materials, but reddish-yellow after passing through the material. Opals are an example.  This opalescent nudibranch was on the wall near Rat Rock.  Actually to me it looks like this nudibranch is lit up like a neon tube from the inside.

Juvenile Rockfish at Tajiguas

I've seen literally hundreds of juvenile rockfish on each dive at Tajiguas and Refugio lately.  This one was at Tajiguas, hanging out next to a sea palm, as part of a school of a half-dozen or so.  There seems to be no particular reason for their abundance -- although rumor has it that abundant juvenile rockfish tend to be associated with El Nino (or Los Ninos?) events. These events come in two varieties, of which only one has becoming more common lately. Both cause warming of the ocean off California. One may be starting now. Perhaps as a consequence, lots of young sea lions have been starving lately, as the fish move to colder waters, too deep for the youngsters to dive. On my last dive at Tajiguas, the second weekend of July, I noticed that temperatures varied between 55F and 60F underwater.  In spots you could see the shimmery division between water of different temperatures.  If this goes on we'll have over 70F by October.  Warm-water diving, anyone?

Online Underwater Field Guide

Christine Donahue, and collaborators Clint Nelson, Dan Reed and Shannon Harrer, have come up with a great field guide to locally common plants and animals. To me, the best aspects of this guide are the algae and inverts.  It resolved a lot of the doubts and questions I have about those plants and animals that you see everywhere on the bottom, and seem to take a few different forms that may be related. Like, what are those big single-bladed algae that look like laminaria, but are completely smooth and have a central rib?  (They are young sea palms). It distinguishes between coastal and island environments: which are pof course retty different.  And, it's free for the downloading:
http://sbcdata.lternet.edu/external/Documents/Publications/FieldGuide.pdf

Marine Reserves are Working

Marine reserves at the Channel Islands are producing more and bigger fish, according to a scientific study reported at a special session of the Channel Islands Symposium.  The study used about 1700 fish counts from REEF.org volunteer divers. So far the results are for relatively rapidly-reproducing fish.  Over the next few years, longer-lived, slower-reproducing fish like rockfish should show some beneficial results as well.  It'll be interesting!

Eelgrass Genetics

Eelgrass is thought to play a crucial role in sheltering young fish and other sea creatures . The eelgrass found  around Santa Cruz and  Santa Rosa is wide-bladed eelgrass (Zostera pacifica).  No eelgrass has been found around San Miguel (to my knowledge) and the eelgrass bed on Anacapa, at Frenchy's Cove, was destroyed by storm and replanted from Santa Cruz.

Coyer and collaborators have published an ambitious study of the genetics of eelgrass in the Channel Islands and along the Pacific Coast.  The eelgrass at Santa Cruz and Santa Rosa is genetically fairly diverse, but genetically distinct from eelgrass beds at other islands; it's quite distinct from the eelgrass in beds off Isla Vista and Goleta Beach.

The uniformity is surprising, since these islands (and their eelgrass beds) span such a wide range of underwater climate and inhabitants: famously, the northern islands are more like Oregon than like the southern islands; which in turn are more like Mexico than like the northern ones.

The eelgrass at Isla Vista and Goleta Beach had long been thought to be invasive: perhaps Zostera asiatica from Japan.  But, it turns out to be Zostera pacifica, a native; and most closely related to that at the Channel Islands.

The eelgrass around Santa Catalina and San Clemente also tells an interesting story, with lots of variation and two distinct species that have apparently hybridized. Human intervention and re-rooting of plantlets dispersed by storm may have played important roles there.

Coyer and collaborators suggest that the eelgrass populations at Santa Cruz and Santa Rosa date back to the last Ice Age, when all the islands were connected into one big one. It's an interesting thought. At the moment, at least, the eelgrass at Santa Cruz and Santa Rosa seems to be a persistent native population.