Photo of the Week: August 09, 2010

Hi Gang!

Its finally getting into summer, and in southern California where I live that means that we are definitely headed into the best part of our diving seasons which is generally considered to be late summer and fall. With longer days, more sunshine, warmer water and good visibility, it is time to head for the kelp forests. No doubt about it, on days when conditions are favorable, few places on earth are as inviting as a southern California kelp forest.

Many years ago when I was in school, giant kelp (Macrocystis pyrifera) was often referred to as the world’s fastest growing plant. Of course, in those days taxonomists told us there were only two kingdoms of living organisms, plants and animals. Having conducted much more research, these days taxonomists claim there are at least five kingdoms, and some claim several more. As far as giant kelp is concerned, it is a type of brown algae, not a plant. Giant kelp is correctly referred to as a type of seaweed.

Algae are simpler than flowering plants as they lack the specialized tissues to carry food and water from one part of to another as flowering plants do. Despite their relative simplicity, seaweeds demonstrate a remarkable ability to survive in conditions that are too harsh for flowering plants. Giant kelp, the species that is the mainstay of the kelp forests along the southern California coast, provides a classic case in point as this species thrives in areas where water motion and current are too strong for many other plants.

Kelp fronds commonly grow in concentrations known as forests, or beds. Some kelp forests cover an area as large as ten square miles or more, while others are as small as only a few hundred square yards. Kelp forests are found in coastal waters over rocky bottoms where the water temperature is 68 degrees Farenheit or lower. Typical kelp forests are located on the perimeter of deepwater drop-offs. At these locations there is usually an additional influx of nutrient-rich cold water that. This high productivity supports both the entire kelp forest ecosystem by proving food and shelter for myriad species including the kelp.

Occurring from Santa Cruz, CA to Turtle Bay, Mexico, giant kelp is the oceans’ largest and fastest growing kelp. A single frond can attain a length of 200 feet, increasing in length by as much as two feet per day when growing conditions are ideal. Supported by gas-filled air bladders known as pneumatocysts (not to be confused with the stinging nematocysts of corals, jellyfishes and other cnidarians), giant kelp grows upward from the sea floor and eventually floats on or near the surface forming a thick surface canopy where it can take maximum advantage of the life-sustaining rays of the sun.

This week’s POTW is an image of the surface canopy in a giant kelp forest. In the shot you can see a number of golden fronds floating on the surface. This is a common scene in late summer and fall in a healthy southern California kelp forest.

I captured this photograph with a Nikon 12-to-24 mm lens set as 20 mm. I used a pair of Ikelite 160’s to add some fill light in the darkest areas of the canopy, but the primary light source that illuminated this image was sunlight. There is a natural tendency to descend and get out of the thick canopy when first entering a kelp forest, but I was only three or four feet deep when I took this shot, and this image provides a classic example of the fact that there are some excellent photographic opportunities in shallow water.

I hope you enjoy this week’s POTW!

See you next week,

Marty