Pigeon Point intertidal

Pigeon Point in San Mateo County, CA is one of my favorite tidepooling
locations and I have visited this area for many years. In late March I returned
to the south side of the point. Here waves crash into rocks with a population of
the sea palm, Postelesia palmaeformis. The Pigeon Pt. lighthouse is in the
background.

Many of the palms exhibited desiccation stress, perhaps due to a combination
of mid-day low tides, warm sun, and wind. 

Another of my favorite kelp species on the California coast is this species,
Dictyoneurum californicum. It occurs as clusters of blades on rocks in
the low intertidal. I love the color and texture of the blades. 

At least two species of seagrasses in the genus Phyllospadix appear
to be present at Pigeon Pt. Here is P. scouleri underwater. It
occupied the low intertidal, often in channels between higher rocks.

Red seaweeds (Rhodophyta) are the stars of the show at Pigeon Pt. since they are in such high abundance relative to other seaweeds. Here is a sampling of species. From left to right is Osmundea spectabilis, Sarcodiotheca gaudichaudii (with some small epiphytic Microcladia coulteri), and a coralline alga - the most unusual "rhodolith" I've ever seen!

"Leafy" red seaweeds were relatively common in the low intertidal too. I
think this is one of the Botryoglossum species (Delesseriaceae).

Out on the rocks near the sea palms there were a few deeper tide pools
that had anemones, and high concentrations of purple urchins. 

I found a sculpin in one of these pools as well.

Finding this tube worm, Serpula columbiana, and photographing it underwater
was a treat. The colorful plume is used to catch food and accomplish gas change.
The operculum can be seen behind the the plume at top right. It is used to seal up
the tube when the animal retracts. Hat tip to my friend Allison Gong for the
species name. 

Ten Mile State Marine Reserve

Intertidal and offshore pinnacle at Ten Mile State
Marine Reserve, Mendocino County, CA, Jan 2015.

Friday was a bright sunny winter day on the northern California coast. I went tidepooling at Ten Mile State Marine Reserve a few miles north of Fort Bragg in Mendocino County. I discovered this site years ago and named it site 71.70 from the mile marker for nearby state highway 1. In 2012, this area was incorporated into a state marine reserve. Access to the intertidal is down a hundred foot coastal bluff which is impossible in most places except for a steep thin trail that leads down loose soil and rocks. It isn’t the easiest trail, but it isn’t particularly harrowing either if one is careful.

There are abundant intertidal gardens and tide pools here among dark boulders of various sizes. Numerous pinnacles and rocks off shore provide some protection to the immediate coastline, which is a fairly narrow beach consisting of coarse sand, cobbles and bedrock. The swells were relatively calm. January is about the least optimal time to observe the glory of marine algae in the northeast Pacific, but there were perennial kelps, rockweeds and red seaweeds present on the rocks. Photos from my last visit during summer 2008 indicated that patches of the sea palm Postelsia palmaeformis were present on intertidal rocks at this site, but there was no sign of that species today. Perhaps new sporophytes (adult plants) of this species will appear this coming spring.

Left: Intertidal Postelsia population in summer 2008. Right: Jewel top snail, 2015.

One of the most striking plants I observed today was Codium setchellii, a dark green (almost black), seaweed of velvet texture that spreads over rocks in the lower to mid-intertidal zone. It is sister to another green seaweed, Codium fragile, that has the popular name of “dead-man’s fingers” because of its cylindrical dark green branches. Instead of morbid appendages hanging pendant on the rocks, however, C. setchellii grasps the substrate with crenulations that aren’t too dissimilar to a human brain. I think therefore, in honor of its relative, an appropriate common name for this plant is “dead man’s brains”.

Codium setchellii, aka "dead man's brains"!

This tidepooling trip was also the maiden voyage for a new “action” video camera I purchased. I’ll need to practice the underwater techniques in the future, but I’ve included a short video of some tidepool footage. 

Looking north at Ten Mile State Marine Reserve from the coastal bluffs, Jan 2015.

Carmel tidepools

Costaria costata, 2014.

The Monterey Bay area is one of the coastal gems of California: strikingly beautiful marine life, diverse and easily accessible tide pools, and a rich tradition of marine research and education. Ever since my undergraduate days at UC Santa Cruz, I've loved to explore tidepools from the San Mateo County coastline south to Monterey and Big Sur. Spring-time low tides are an ideal period to visit the rocky intertidal, though that often necessitates an early rise of 5 or 6 AM to catch the action.

Carmel Point is one of my favorite places to tidepool. It is a few minutes south of the Monterey Peninsula by car. The town of Carmel is probably one of the most affluent coastal communities in California, but it is small and has a laid back feel. Carmel Point is a short stretch of rocky coastline that interrupts two more-or-less crescent shaped coves of sandy beach to the north and south. Offshore kelp forests run right into the low intertidal, so at the right times one can literally walk through a grove of giant kelp by just getting wet up to the knees.

Panorama at Carmel Point. Tidepools extend to the south. The Monterey peninsula is in the distance at center and right.

Corallina officinalis, 2014.

Carmel Point is an incredible spot for seaweed lovers like myself. There are interesting finds in all of the three major phyla of marine seaweeds. Green seaweeds are represented by alluring plants like "dead man's fingers" (Codium fragile) and the delicate Bryopsis. Reds appear in their varied hues, including the rich blades of Chondracanthus and Erythrophyllum delesserioides. There are various species of branching coralline algae in the lower to mid intertidal, lending a vibrant pink to the mosiac of benthic organisms on the rocks. 

Low intertidal Macrocystis pyrifera, 2007.

And, of course the large and conspicious brown algae are very diverse here. In addition to long strands of giant kelp (Macrocystis pyrifera) in the intertidal, there is bull kelp (Nereocystis), low intertidal groves of Laminaria setchellii and occurrences of feather boa kelp (Egregia menziesii) and Alaria marginata. The higher rocks host several species of rockweeds: Fucus distichus, Pelvetiopsis limitata, Silvetia compressa and Hesperophycus californicus.

Chondracanthus exasperatus, 2014.

I've made a half dozen or so trips to this site over the years, so I'm starting to have a few places I can check for favorite seaweed species. For instance, I've observed during intermittent visits a mid-intertidal population of the sea palm, Postelsia palmaeformis. The population this year grew on only a single rock, and plants looked a little tattered. One of my all time favorite kelp species, Costaria costata, appeared to be pretty common this spring. I found it in a usual pool just south of the Postelsia rock and in a high density at another low intertidal spot.

The nudibranch Triopha maculata on an opaque tunicate, 2014.

While tidepooling, my attention is usually taken with the seaweeds, but occasionally I notice some showy invertebrates too. This spring I found three species of colorful nudibranchs. On a previous visit I found a really cool green shrimp, its body colored perhaps from ingesting green algae.

Super cool green shrimp, 2009.

A small bull kelp, Nereocystis luetkeana,
submerged in a tidepool, 2010.

One thing I thought of during my visit this spring to Carmel was the intellectual challenge of understanding the ecology of these diverse rocky intertidal communities. There are literally hundreds of species of benthic algae and invertebrates packed tightly into the complex amalgam of bedrock, boulders and sand. Sure, there is the obvious vertical zonation of species that is driven heavily by the tides, but there is also so much three dimensional habitat structure creating seemingly infinite combinations of light, wave energy, sand scour and temperature. Add to these physical gradients the host of possible biological interactions (competition, herbivory, facilitation) among the dozens of co-existing species, and the unique life history patterns of immense phylogenetic diversity, and comprehension of the grand picture can seem unattainable. So, an observation here or experiment there that lends insight into these incredible ecosystems is a tremendous intellectual reward.

The strawberry anemone, Corynactis californica, growing underwater in the low intertidal, 2014. 

This is a small red alga, Pterosiphonia dendroidea, that I captured with my macro lens growing in a sandy area at Carmel Point in 2009. Most fronds of this plant are only a few cm in length. I love how individual cells can be seen on this plant!

Incredible plants: the sea palm

The sea palm, a rocky intertidal kelp found along western North American shores is one of the most distinctive seaweeds in the world. In shape it is remarkably similar to terrestrial palm trees; it has a knobby holdfast for firm attachment to the rocks, an elastic stipe for flexibility, and a tuft of drooping rugose blades at the top. The species name is Postelsia palmaeformis and it was first described by western science in 1852 based on collections made during a Russian expedition to western North America in 1839 (Abbott and Hollenberg 1976).

 

Individual sea palm (left) and grove (middle) at Carmel, Monterey Co, CA. Close-up of the holdfast on a plant at Gleason Beach, Sonoma County, CA. (right).

Postelsia is distributed on rocky shores from central California to British Columbia. It occurs at about the middle intertidal zone, so only a moderately low tide is necessary to see it exposed. However, it is not among the safer seaweeds to hunt for along the coast since it grows on highly-wave exposed shores where it is beaten by the surf. Research by Paul Dayton and Robert Paine in Washington State has shown that this wave energy is necessary for persistence of this annual species in the rocky intertidal (Dayton 1973, Paine 1988). Sufficient wave action removes carpets of sessile mussels, giving the sea-palm bare space to colonize. Or, in some cases, juvenile palms settle on mussels or algae and eventually cause both species to get removed by waves from the rock and open more space – a sort of suicide for the good of the species (Dayton 1973). Without the assistance of physical disturbance, mussels would dominate the rocks leaving no space for Postelsia.



A grove of Postelsia at Glass Beach in Mendocino County, CA takes an incoming wave.



Newly recruited sporophytes, Gleason
Beach, Sonoma Co., CA.

Sea-palms occur in gregarious patches because their spores typically only disperse short distances (Dayton 1973). Perhaps during rising tides, spores drip from the hanging fronds of the plant onto adjacent rocks and settle rapidly (Paine 1988). There they germinate into a microscopic stage of the kelp life cycle known as the gametophyte. Sperm from male gametophytes fertilize eggs attached to female gametophytes, and there start a new generation of adult plants (the sporophytes).



Sampling some "sea crunchies"
(dried sea palm blades) made by a
company in northern California.

Like some other seaweeds, Postelsia is edible. Seaweeds tend to be rich in minerals like iodine, but they may also have high levels of more toxic metals, so they should probably be eaten only in moderation.










References
Abbott, I.A. and G.J. Hollenberg. 1976. Marine Algae of California. Stanford University Press, Stanford, CA.
Dayton, P.K. 1973. Dispersion, dispersal, and persistence of the annual intertidal alga, Postelsia palmaeformis Ruprecht. Ecology 54:433-438.
Paine, R.T. 1988. Habitat suitability and local population persistence of the sea palm Postelsia palmaeformis. Ecology 69:1787-1794.