Brilliant White Sands

White Sands National Monument, New Mexico.

White Sands National Monument in southern New Mexico was stunning and exceeded my expectations. It will undoubtedly be one of the highlights of my trip through the Southwest this spring, made so in large measure because I was able to camp in the backcountry overnight.

The dunes are a brilliant white color due to being composed of gypsum (selenite) sand. They are remarkably cool to the touch, which is counter-intuitive for anyone who has spent time on a sandy beach in the warm sun. Because the sand was so cool and soft I was able to do some hiking in bare feet. The mineral composition of the sand (selenite is a hydrated mineral) and the relatively high water table in the dunes apparently help keep it cool.

The dunes are extensive, covering close to 300 square miles in a valley east of the San Andreas Mountains in southern New Mexico. A US military missile testing range is the Monument’s neighbor on three of its four sides, and sometimes the Monument closes because of missile activity.

Like coastal beach dunes, some of the gypsum dunes at White Sands had a modest cover of vegetation, while others were barren. Plants were more apt to be found in flat interdune areas that may provide longer-term stability from the vagaries of shifting sand. The most attractive flowering plant was sand verbena, with hemispherical clusters of light purple flowers. The only animal life I really saw was two species of beetles, though the Park Service made a point to illustrate that populations of animals (mammals, reptiles) inhabiting the dunes had adapted to become lighter in color than nearby populations which live in habitats with darker substrates.

Some dune vegetation, including a Yucca (or similar species), small trees that may be cottonwoods (Populus), and purple-flowered sand verbena.

 

Dune beetles.

Sunset over the dunes.

White Sands is a photographer’s dream, at least for the style of photography I am interested in. From the macro to landscape scales there were alluring subjects, curves, and shadows all around. I found the most compelling time for photography to be perhaps an hour or two before sunset and an hour or two after sunrise. During this period when the sun was low on the horizon, it cast beautiful shadows over the dunes and seemed to provide an ideal level of contrast. The white sand in the shadows in the early morning often appeared purple to me.

One feature of the dunes that I found particularly attractive was the parallel ripples, typically no more than a few centimeters in height over the dune surface. There are analogous undulations in coastal sand caused by water, and the ripples in the middle of this desert brought to mind the fact that air (wind) is like a fluid, acting to shape the substrate below it by its direction and strength of flow.

White Sands is certainly a park I would visit again, hopefully in the same fashion as this trip: sleeping under the moon and stars in a dunefield of sublime beauty.

Animal tracks.

Different ripple patterns on the surface of the dunes.

Shadows cast at a dune crest.

An interdune area with rougher texture, I suppose composed of selenite crystals.

Looking south over the dune field with the early morning sun casting shadows to the west.

My campsite and hiking barefoot in the dunes.

Quitobaquito

Along the US-Mexico border, about 15 miles west of the border crossing between Lukeville, Arizona and Sonoyta, Mexico is the small oasis of Quitobaquito in Organ Pipe Cactus National Monument. The shortest route to the site is a dirt road that, for much of its length, parallels the international border. In fact, in places it is no more than 20 meters from the metal fence on the US side, a barrier less formidable than many backyard fences. The saguaros and desert scrub take no notice of the artificial line in the sand so important to humans.

At Quitobaquito, perhaps a half kilometer north of the border, a tiny creeklet finds its origin in a spring that itself seems to just emerge from the base of a small non-descript slope of dry Sonoran Desert soil. The Park Service has lined the creeklet with concrete, no doubt to preserve the integrity of the waterway, because so minute is the flow that it seems like the desert dust could consume the trickle of water with no effort. As I walked along the creeklet, looking for its source, I could see signs of researcher presence – a short submerged PVC tube that I’m guessing houses a temperature sensor or other device, and some red plates underwater about which I cannot surmise their purpose.

Arriving at Quitobaquito (left) and some saguaro cacti near the oasis (right).

The creeklet ends in a rather large shallow pond to the south which is encircled by a narrow but dense band of sedges (just like Schoenoplectus americanus of west coast wetlands, though I’m not positive it is the same species). It looked like there was widgeon grass (Ruppia) in the water. The pond and creeklet were lined with colorful flowering species that I had not seen elsewhere in the Monument.

The pond at Quitobaquito. Sedges line the edge of the pond.

Why the effort to protect flow in the creeklet? This little oasis is home to an endangered fish species, the Quitobaquito pupfish (Cyprinodon eremus). I saw quite a few fish in the creeklet that led to the pond. The species is dimorphic in color – larger blue fish are reproductively mature males and females and immature males are smaller and light grey-brown, blending in well with the substrate. Incredibly these pupfish can tolerate high salinity, very high temperatures, and low oxygen conditions. The fish I observed were skittish and apparently territorial, chasing one another in short bursts of activity.

Quitobaquito pupfish. A arrow points to the female or immature male at left since these fish
blend in much better with the mud than the blue reproductive males.

Flowering plants near the pond: Heliotropium curassavicum (left) and Funastrum cynanchoides (right).

References

Reistad, A. 2012. Pupfish. In: National border, national park: A history of Organ Pipe Cactus National Monument, at: https://organpipehistory.com/orpi-a-z/pupfish/

Spellenberg R. 2012. Sonoran Desert Wildflowers. 2^nd ed. Falcon Guides, Guiford, MT.

Flowering plants near the creeklet: Anemopsis californica (left) and unknown pink-flowered species (right).

Arizona cacti

Heading east from San Diego I descended into the hot Imperial Valley and the Sonoran Desert. Ocotillos appeared signaling entry into this desert province. After a relatively cool spring in northern California, I wasn’t quite ready to be thrust into summer temperatures. My first major destination was Organ Pipe Cactus National Monument, just north of the Arizona-Mexico border. It lies right in the heart of the Sonoran Desert.

Organ Pipe and other cacti at Alamo Canyon.

Night sky at Organ Pipe Cactus National Monument.

I first visited Organ Pipe 20 years ago, when with a class of UC Santa Cruz students we descended on northern Mexico to study the ecology of the Gulf of California. The road to Sonoyta, Mexico passes bisects the monument. I arrived after dark, and turned up a dirt road to a small campsite at the head of Alamo Canyon. It was a warm evening. I stayed up for some time photographing landscapes dominated by Saguaro cacti. A half moon shone brightly in the sky above but was gone by 4 AM when I awoke again to photograph stars and the Milky Way.

With the new day, the diversity of cacti was evident from the start. Saguaros were very common, and organ pipe cacti became more common as I made my way up the valley for a morning hike. There were menacing cholla cacti, with their beautiful golden spines covering plants like a blanket. I also recognized the prickly pear cactus, Opuntia.

The organ pipe cactus (Stenocereus thurberi) is a collection of rather large stems, emerging from a common base. The namesake of the monument, the species is more common in Mexico than in the US and has a limited presence here due to its intolerance of frost. Flowers apparently only open during the night and are primary pollinated by bats.

Saguaros (Carnegiea gigantea) were actually very common at Organ Pipe Cactus NM, growing in most regions of the monument that I observed. However, there is a whole national park named in honor of this species, and that was my next destination. Bisected by the city of Tuscon, Saguaro National Park comprises two units east and west of the city. I briefly visited some of both, catching the sunset at the west unit and doing some morning hiking at the east unit.

Saguaro cacti. Left: spines (which are actually modified leaves on cacti) on a plant at Saguaro NP. Right: An open flower on a plant at Organ Pipe Cactus NM.

The morning of my hike started off warm. I began at a trailhead at Loma Verde and hiked about 2 miles into the Saguaro Wilderness along the Squeeze Pen and Carillo trails. Saguaro, barrel cacti, and Opuntia were common. Mesquite, palo verde (literally, “green stick”), and other trees and shrubs were also abundant in the area. At Wildhorse Canyon I found pools of water remaining in a wash.

Flowering cholla cacti at Saguaro NP. At left is the pencil cholla, Cylindropuntia arbuscula.

Though not a cactus, ocotillos were common at both Organ Pipe Cactus and Saguaro NP and were frequently in bloom, their bright red flowers adding color to the landscape. At Saguaro I saw many ocotillos with leaves (some green, some senescing), a sight that may not be particularly common since these plants readily shed their leaves during times when water is scarce. It is a true deciduous desert species.

Ocotillos. Left: With leaves at Saguaro NP. Right: Hummingbird visiting flowers at Organ Pipe Cactus NM.

Wildlife was fairly common at both of these desert parks. I saw coyotes (Organ Pipe), a Gila Monster (Saguaro), a hummingbird (Organ Pipe) and other birds, a deer (Saguaro), Desert pupfish (Organ Pipe), and lots of lizards (both parks).

Barrel cactus, Ferrocactus, at Organ Pipe Cactus NM.

Chainfruit cholla cactus, Cylindropuntia fulgida, at Organ Pipe Cactus NM.

An organ pipe cactus near the US/Mexico border that is half skeleton at this point.

Prickly pear, barrel cactus, and saguaros at Saguaro NP.

Sunset with Saguaro cacti and ocotillo at Saguaro NP.

California's marine biogeographic break

Felimeda macfarlandi, a chromodorid nudibranch at Cambria.

This month I’m repeating my spring road trip through the southwest, but oppostite of my general course last year, I’m first heading down the California coast. My focus is on marine life for a few days and then I head to the deserts and mountain ranges inland. Cambria was my first stop on Thursday morning on the central coast just south of Big Sur.

At Cambria, fleshy red seaweeds, surfgrass, kelps, and invertebrates filled out the rocky sandstone boulders and bedrock. I again saw a healthy population of the rockweed Pelvetiopsis hybrida, a seaweed I first encountered and wrote about last year. There were adorable small sporophytes of bull kelp in a handful of small patches in the low intertidal. One new find was a beautiful purple chromodorid nudibranch, gliding among leafy red algae.

Young sporophytes of Nereocystis luetkeana (bull kelp)
in the low intertidal at Cambria. Egregia menziesii is in
the background.

Friday morning I was at the Palos Verdes Peninsula in Los Angeles. Remarkably I have never been tidepooling in LA County despite growing up in the region and attending graduate school in San Diego. Pt. Fermin was my planned destination, but when I arrived there in the morning, all access was officially blocked off. Skirting around a barrier would have been no problem, but it didn’t seem advisable. Instead I drove a little farther north to White Pt.

Relatively strong surf pounded some high relief rocks in the intertidal just off the southern parking lot. I explored a section of coastline south of there, almost to White Pt. itself. The site was comprised of sandstone benches, boulders, and cobbles, a drab yellow color.

The changed character of the biota between central California and Los Angeles was immediately evident. I was struck with the incredible abundance of barnacles in the upper intertidal at White Pt. – a desert as far as macroalgae were concerned. Red fleshy seaweeds were essentially non-existent, and the large seaweeds (a few species of kelps and large brown algae) were generally limited to the low intertidal zone.

I had crossed a well-known biogeographic barrier by entering southern California, and the marine flora in particular indicated this dramatic change in biotic composition. Point Conception north of Santa Barbara is often regarded as the break; this is where the mainly north-south coastline of northern and central California bends toward the east to form the southern California Bight. North of Point Conception, water temperatures are cooler and there are pockets of coastal upwelling that bring nutrient-rich cool water to shallow depths for photosynthetic organisms to enjoy. The north-to-south California Current dominates the near-shore. South of the point, waters are warmer and the south-to-north Davidson Current is present. Hot and dry Santa Ana winds that blow from the northeast can bake the southern California coast.

A wave crashing into sandstone benches just north of White Pt., Los Angeles Co.

A cowrie at White Pt.

Desiccation stress, always a concern for aquatic organisms which are periodically exposed to air, may be more intense in southern California than in more northerly parts of the state. More intense sun, less rainfall, and warmer temperatures in southern California probably exacerbate desiccation stress in southern California.

I found the abundance of small barnacles in the high intertidal curious. These organisms must be hardy against desiccation – they are exposed to air most of the time after all – but I wonder how being clamped tightly shut most of the time affects their ability to capture food. They must open up and sweep the water in order to catch food particles.

Except for the low intertidal which is submerged often, tidepools were the other microhabitat at White Pt. where larger seaweeds were likely to be seen. Relative to the central coast, however, these were not particularly large, consisting of branching coralline algae, Gelidiales, and others. Small fish darted to hiding spots when they sensed me nearby.

Common low intertidal kelps north and south of Pt. Conception. Left: Laminaria setchellii at Cambria. Right: Eisenia arborea at White Pt.

One of the interesting kelps of southern California that is not seen farther north is Eisenia arborea. Its species name suggests “tree”, and that is not an inaccurate moniker. Eisenia is a small kelp species, born on a stiff stipe from which two sets of blades droop down in a sort of disheveled brown mess. At White Pt. it was almost exclusively in the low intertidal, with some stragglers a little higher up where pools were present. Eisenia also occurs in Japan. In central and northern California Laminaria setchellii takes its place in both overall form (though it is not such a mess) and in ecological niche. I’m curious to know if these species overlap in distribution at all, or where one begins exactly and the other ends. Some exploration of Santa Barbara and the northern Channel Islands holds the answer to that question I think.

Juvenile spiny lobster (Panulirus interruptus) in a tide
pool at La Jolla. It's carapace was about 3-4 cm long.

Today I was in La Jolla. The flora was different yet again, but more similar in overall growth form to White Pt. than Cambria. Eisenia was present, but so too was a small kelp, Laminaria farlowii, that I didn’t see in Los Angeles. These plants are simple ruffled blades, aggregating or growing as singlets in the low intertidal. La Jolla also had a remarkable contingent of brown seaweeds of the order Dictyotales. This group tends to favor tropical and subtropical regions globally.

At La Jolla I explored the area around Nicholson Pt., a series of sandstone benches between the posh homes and the Pacific. Ravines, and even an arch, were cut into the sandstone. In the mid and high intertidal were also pools of various depth and diameter – all providing a variety of microhabitats for marine organisms. The beautiful marine plants notwithstanding, today’s best find was probably a tiny lobster in the warm water of a pool in the mid-intertidal! I’m tempted to tidepool once more tomorrow morning, though I originally planned to leave early for Arizona. We shall see!

Zonaria farlowii (Dictyotales) was very common in low elevation
sandy tide pools at Nicholson Pt., La Jolla. This species grows in
elegant rosettes.

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.