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The marine macroalgae, or seaweeds, are classified into three phyla: Ochrophyta (brown algae), Rhodophyta (red algae), and Chlorophyta (green algae). Along the California coast the reds are the most diverse, with several hundred species. The browns have the largest thalli (the phycologists' term for the bodies of algae), including the very large subtidal kelps as well as the smaller intertidal rockweeds. The green algae are small in both thallus size/complexity and species diversity; many of the greens are filamentous and look like nothing more than slime growing on rocks or other surfaces.

On the other hand, what appears to be simple at first glance can turn out to be delightfully complicated and puzzling upon closer examination. Take, for example, the two species of green algae in the genus Codium that occur intertidally in northern California: Codium setchellii and C. fragile. Codium setchellii is a native species here. It grows as a thick rugose mat over rocks in the mid-intertidal. Its color is a very deep olive green, but when dry it looks almost black.

Codium setchellii at Franklin Point
15 June 2018
© Allison J. Gong

Codium setchellii has a smooth texture and feels like very thick velvet. It grows on vertical faces of rocks, rarely on exposed horizontal surfaces--at least, I've not often seen it on top of a rock. Patches of C. setchellii are usually about the size of my outstretched hand, although some can be a little larger than that. When you see C. setchellii in the field, it's hard to imagine what type of structure would result in a thallus like this. To figure out what's going on, you need to look at small pieces under a microscope. It's this level of observation that reveals the filamentous nature of C. setchellii.

Phycologists have a few tricks for observing the internal structure of algae. The firm-bodied algae can be examined via cross-section, which can be more or less difficult to make depending on the species. Many simpler thalli, however, can be examined by making a squash, which is exactly what it sounds like: You take a piece of the alga, place it in a drop of water in a slide, and squash it with a cover slip.

A squash of C. setchellii revealed this mishmash of filaments:

'Squash' of Codium setchellii, viewed at 100X magnification
26 June 2018
© Allison J. Gong

This particular squash shows the utricles, which are the pigmented ends of the filaments. It didn't really help me understand how the filaments are organized within the thallus, though. I even tried making a cross-section of the little piece of C. setchellii I have, but it turned to mush. I did at least get one squash that showed the filaments to be arranged in approximately parallel fashion at the outer edge of the thallus.

Utricles of Codium setchellii, viewed at 100X magnification
19 July 2018
© Allison J. Gong

So, seeing the internal structure of Codium setchellii allows me to understand how its closely packed filaments produce the velvety cushion of the thallus that I see in the field. The way that the filaments are aligned allows them to be tightly packed together, resulting in a cushion that is surprisingly firm rather than squishy.

The second species of Codium that we see in northern California is C. fragile, commonly called 'dead man's fingers'. It is a non-native species here, originating in the western Pacific near Japan, and has spread into the Atlantic. In California it has a patchy distribution and, in my experience at least, isn't as common as C. setchellii. I have never seen the two species together at the same site, but according to iNaturalist they do co-occur in some locations.

Like its congeneric species, C. fragile is a dark greenish color and lives in the mid- to low-intertidal. But otherwise it looks entirely different. The thallus morphology must be what gave rise to the common name. I remember learning years ago about a seaweed called 'dead man's fingers' and being disappointed when I saw it for the first time. It didn't look like dead man's anything!

Codium fragile at Asilomar State Beach
16 June 2018
© Allison J. Gong

This thallus resembles a clump of approximately dichotomously branching tubes. It is spongy in texture and is often colonized by bits of a filamentous red alga.

The green alga Codium fragile, with red algal epiphytes
19 July 2018
© Allison J. Gong
Epiphytes on Codium fragile
19 June 2018
© Allison J. Gong

In this case, the red alga (Ceramium sp.) is in turn colonized by the benthic diatom Isthmia nervosa:

Benthic diatoms (Isthmia nervosa) growing as epiphytes on the filamentous red alga Ceramium, viewed under darkfield lighting
19 July 2018
© Allison J. Gong

You might expect Codium fragile, having a tubular morphology, to be more amenable to being examined in cross-section. I can tell you that that isn't the case. It's easy enough to make the first transverse slice of one of those 'fingers', but the second slice, even made with a brand new razor or scalpel blade, results in a pile of mush. I made and looked at several such piles, hoping that at least one would show an approximation of the cross-sectional anatomy of this thallus. The best I could get was this:

Pigmented utricles of Codium fragile
20 July 2018
© Allison J. Gong

At least it shows the radiating arrangement of the filaments. I think this is really interesting. The utricles (pigmented tips of the filaments) are a bit thicker than the unpigmented section of the filaments that make up the interior of the cylinder, but there's still space between them at their distal tips. It is this arrangement that gives Codium fragile a squishiness that C. setchellii lacks.

So there you have it. One genus, two species with radically different gross morphology but similar internal morphology. They're made of the same types of cells, at least. Like I said, I've not seen them in the same place in the field, but here in my blog you can see them side by side.

Codium setchellii at Davenport Landing
13 December 2016
© Allison J. Gong
Codium fragile at Asilomar State Beach
16 June 2018
© Allison J. Gong

The Sierra snowpack is California's largest single reservoir of fresh water, accounting for 1/3 of the state's water supply1. A state with a mediterranean climate, such as California, receives precipitation only during the short rain/snow season. During years of drought, when the average Californian frets about how little rain is falling, state water managers are keeping a worried eye on the amount of snow falling in the Sierra. Snow surveyors use remote sensing and field measurements to estimate the water content of the snowpack. The snow water equivalent on 1 April is used to compare snowpack water content across years.

The 2016-2017 snow year was a productive one, dumping near-record amounts of 'Sierra cement' on the mountains. (Skiers accustomed to the powder snows of Utah and Colorado often disparage the heavy snow in the Sierra, but Sierra cement carries a lot more water than powder so is much more beneficial to the state's water supply). Most of that snow eventually melts, births streams and rivers, and flows from the mountains to lower elevations. After a good snow year, though, snow fields remain at high altitudes even during high summer. That definitely is the case around Lake Tahoe.

A few days ago my husband and I hiked from Carson Pass to Big Meadow, a through hike about 8 miles long. The hike goes through some gorgeous alpine meadow, with an absolutely stunning display of wildflowers. Even in late July we had to cross several streams and saw lots of snow.

Round Top Mountain, viewed from meadow above Carson Pass
25 July 2017
© Allison J. Gong
Snow field in the high Sierra
25 July 2017
© Allison J. Gong

If you look closely at the bottom photo, you may notice some faint pink streaks on the face of the snow field. This pink snow is called 'watermelon snow' because of the color. It is a phenomenon that occurs only at high altitudes or polar regions in the summer. Here's a closer look, taken with a 70-200 mm lens that I rented for the week.

Watermelon snow
25 July 2017
© Allison J. Gong

Given the color of those streaks, you'd think the organism producing it would be a red alga of some sort, wouldn't you? I did, too, until I did some research and learned that it is a green alga! Chlamydomonas is a genus of unicellular green algae, most of which are indeed green in color because the only photosynthetic pigments they contain are chlorophylls. However, Chlamydomonas nivalis also contains reddish carotenoid pigments that serve to shield the cell's photosynthetic pigments from excess radiation, which is intense at the high altitudes where the algae live. The pigments absorb heat, which increases the melting of snow in the immediate vicinity and provides liquid water that the algae require. Watermelon snow is found in alpine regions across the globe, although it isn't known whether or not the same species of alga is responsible in all cases.

Cross-country skiers and snowshoers pass through these areas in the winter, and never report seeing watermelon snow. What happens to the cells in the winter? Do they die?

It turns out that the alga persists year-round, although in different life history stages. Given the inhospitality of their habitat, most of the life cycle involves waiting in a dormant stage, with a short burst of activity in the spring. The red form that we see in the summer is a dormant resting stage, having lost the pair of flagella possessed by swimming unicellular green algae. These spores, former zygotes resulting from fertilization, are non-motile and cannot escape to deeper snow to avoid UV radiation, so they use carotenoids to serve as sunscreens. They are not dead, though, and continue to photosynthesize all summer. They rest through the winter and germinate in the spring, stimulated into activity by increased light and nutrients, and flowing water. Germination involves the release of biflagellated cells that swim to the surface of the snow, where at least some of them function as gametes. Fertilization occurs, with the resulting zygotes soon after forming the resting spores that result in watermelon snow.

It may seem strange that this organism spends most of its time in a dormant stage, but this is not at all uncommon for things that live in hostile habitats. When conditions for life are difficult, the best strategy can be to hang out and wait until things get better. Chlamydomonas nivalis does this on a yearly basis, as do many of the marine unicellular algae. And some animals, namely tardigrades, can dry out and live for decades or perhaps even centuries in a state of suspended animation, returning to life when returned to water. As with many natural phenomena, this kind of lifestyle seems bizarre to us because it is so unlike how we do things. But if C. nivalis could observe and think about how we live, it would no doubt consider us inconceivably wasteful, expending enormous amounts of energy to remain active at times when, clearly, it would much more sensible (from C. nivalis's point of view) to sleep until better conditions return.

 


1 California Department of Water Resources

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The marine macroalgae are, as a group, the most conspicuous organisms in the intertidal. Yet, most tidepool explorers dismiss them as "seaweeds" and move on to the next thing, which they hope is somehow more interesting. This is akin to visiting the jungles of Brazil and not paying attention to the lush foliage that defines that particular biome. I will admit that, as a zoologist whose primary interest is the marine invertebrates, I have been guilty of this offense. I've also felt guilty about the oversight and thought to myself, "I really should know the algae better." I have no formal training in phycology beyond auditing marine botany labs after I finished graduate school, but I've got the basics down and really have no excuse for the continuation of this gap in my knowledge.

So a couple of years ago I decided to start filling in that gap. I dragged out my marine botany notebook and have slowly been adding to it, building up my herbarium collection at the same time.

The red algae (Rhodophyta) are the arguably the most beautiful of the seaweeds, and inarguably are the most diverse on our coast. Some of them are easy to identify because nothing else looks like them, but many share enough morphological similarity that field IDs can be tricky if not downright impossible. For example, to ID a specimen and distinguish it from a close relative you may need to examine the number, size, and arrangement of cells in a cross-section of a blade. Some species are impossible to identify beyond genus (or even family, in some cases) unless you can look at their reproductive structures, which they might not have at the time they're collected.

One of the most ubiquitous red seaweeds, and one that is easily identified to genus, is Mazzaella. The genus name for this group of species used to be Iridea, which gives a hint as to the appearance of the thalli--many of them are iridescent, especially when wet. The species that I see most often are M. flaccida in the mid intertidal and M. splendens lower down. These species are usually not difficult to tell apart once you get used to looking at them and their respective habitats.

Mazzaella splendens at Whaler's Cove at Pigeon Point
28 June 2017
© Allison J. Gong
Mazzaella flaccida at Natural Bridges
9 July 2017
© Allison J. Gong

Mazzaella splendens is generally a solid brown with sometimes a green or purple cast. It is soft and floppy, and the blades are long (up to 50 cm) and taper to a point. The Marine Algae of California, which we call the MAC, uses the term "lanceolate" to describe this shape. Mazzaella flaccida is green or greenish-purple, sometimes more brownish along the edges; its blades are flexible but a teensy bit crisper than those of M. splendens, and its blades are described as cordate (heart-shaped) or broadly lanceolate.

Got it. That's not too bad, right?

But then you see something like this, and a whole other set of questions comes to mind.

Thalli of Mazzaella flaccida at Natural Bridges
9 July 2017
© Allison J. Gong

Based on habitat alone these are both M. flaccida. The greenish thallus on top looks like textbook M. flaccida, but the lower thallus looks more ambiguous. It has the right size and shape but is the wrong color, and what's up with all those bumps? I brought these thalli back to the lab to examine them more closely. Here are the entries from my lab notebook:

 

 

 

 

 

 

 

Now is the time to bring up the subject of life cycles in red algae. Algae such as Mazzaella alternate through three generations: male and female gametophytes, both of which are haploid; a diploid sporophyte; and a diploid carposporophyte. Here's a diagram that shows how this alternation of three generations works:

Life cycle of some red algae, showing alternation of three generations
© McGraw-Hill

It was easy to see that the bumpy thallus I collected was sexy, while the smooth green thallus was probably not reproductive. Having both thalli in hand, along with the MAC and phycology texts in the lab, I was able to determine that the bumpy brown thallus is actually two generations in one body. So cool! But how does this work? The bumps on the thallus are called cystocarps. In Mazzaella a cystocarp contains the diploid tissue of the carposporophyte surrounded by the haploid tissue of the female gametophyte. Et voilà! Two generations in a single thallus.

Now, what's inside the cystocarp? What does the carposporophyte tissue actually look like? To find out I had to do some microsurgery, first to remove a carpospore (1-1.5 mm in diameter) from the female gametophyte and then to cut it open to see what's inside. What's inside were microscopic diploid carpospores, which grow into the macroscopic sporophyte generation. Forcibly dissected out as they were, they don't look like much, just tiny round cells about 2 µm in diameter.

Carpospores of Mazzaella flaccida
12 July 2017
© Allison J. Gong

The next logical step would be to isolate some of the carpospores and try to grow them up. I wasn't thinking about that at the time and pressed both thalli. However, I do have another female gametophyte with cystocarps that I can investigate further tomorrow. It's probably a fool's errand, as I am not going to bother with sterile media and whatnot. Oh well. Nothing ventured, nothing gained, right?

1

As spring arrives in full force, the algae are starting to come back in the intertidal. The past two mornings I went out on the low tides to look for something very specific (which I did find--more on that later) and noticed the resurrection of the more common red algae. So early in the season the algal thalli are nice and clean, not yet having been fouled or munched. And, like all babies, they're pretty dang cute.

Here's a little clump of Endocladia muricata, a red alga with the common name 'scouring pad alga.' I've also heard it referred to as 'pubic hair alga,' by a former instructor of marine botany who shall remain nameless.

Endocladia muricata growing on the test of the large barnacle Tetraclita rubescens, at Natural Bridges
1 April 2017
© Allison J. Gong

What I tried, and failed, to capture in this photo is that the strands have little thornlike extensions that give them the texture of . . . a scouring pad. Here's a better picture of a larger clump, and if you squint you might be able to see what I'm talking about.

Endocladia muricata
1 April 2017
© Allison J. Gong

And here's another baby red, this gorgeous little piece of Plocamium. When they're young like this the branching structure is easier to see. And isn't that color splendid? Especially with the green of the fresh young surfgrass.

A baby Plocamium, growing among the surfgrass Phyllospadix scouleri
1 April 2017
© Allison J. Gong

What I was really thinking about this morning were the morphological similarities that can make it very difficult to distinguish between different species. For example, there are three species of rockweeds that are common around here: Fucus distichus, Silvetia compressa, and Pelvetiopsis limitata. Rockweeds are brown algae but are usually olive-green in color, and live in the high mid-intertidal above the mussel zone. In some places all three species occur together. Fucus (see below) is easy to recognize because its blades are wider and somewhat straplike, with prominent midribs. When Fucus is reproductive the tips of the blades become swollen and full of a gooey mucilage, which contains the gametes. There are other interesting things about sex in Fucus, and at some point I may address those in a later post.

Fucus distichus, a rockweed, at Franklin Point
17 July 2017
© Allison J. Gong

The other rockweeds, Silvetia and Pelvetiopsis, are a lot more difficult to distinguish. They both have less straplike blades. They share a generalized dichotomous branching pattern, but in neither is it as consistent as it is in Fucus.

Pelvetiopsis limitata at Mitchell's Cove
2 April 2017
© Allison J. Gong
Silvetia compressa at Mitchell's Cove
2 April 2017
© Allison J. Gong

 

 

 

 

 

 

 

 

 

This morning these two specimens were growing side by side. In terms of scale the overall length of Silvetia is about twice that of Pelvetiopsis. Keeping that in mind, what you can't tell from these photos is that Silvetia is also coarser and stiffer, like pasta that is about a minute short of being cooked al dente--not hard, but still more firm that you'd probably like it to be. Pelvetiopsis, on the other hand, is rather soft and much more flexible.

If I were to ask you to contrast these organisms based solely on the photos above, you might say that Silvetia looks somewhat less orderly than Pelvetiopsis. And you would be right! The almost-but-not-quite-dichotomous branching in Silvetia doesn't always occur in the same plane, resulting in a thallus that doesn't lie flat. Look at this:

Silvetia compressa at Mitchell's Cove
2 April 2017
© Allison J. Gong

See how those branches, especially the terminal branches, don't all come off in the same direction? That's what I mean. A cross-section of Silvetia's blades would be somewhere between flat and cylindrical, also contributing to the tendency of this thallus not to lie flat. This means that when you press it it does get a little mashed looking.

Pelvetiopsis, on the other hand, is a much more regular beast. The blades are distinctly linear in cross-section and generally branch in one plane. One other thing to note is that in Pelvetiopsis the terminal branch tips are very short relative to the overall thallus length compared to those of Silvetia.

Blade tips of Pelvetiopsis limitata
2 April 2017
© Allison J. Gong

A fair question to ask is: How can you tell the difference between a baby Silvetia and a full-grown Pelvetiopsis? Absolute size might not be a useful characteristic, but the other morphological traits are. The branching orientations and overall blade shapes are fairly consistent throughout the size range for each species. Consistent enough, at least, to make a good gut-level first ID guess.

I wanted to write about this because I saw the organisms, checked them off in my head, and then backed up a bit. I found myself second-guessing my instincts when it came to identifying these specimens. I mean, I know these organisms. Or, I think I do. It's frustrating to look at the creatures I see regularly in the intertidal, organisms whose names I learned many years ago (even through the inevitable taxonomic name changes), and say to myself, "Wait a minute; is that right?" This led me to seriously consider these two rockweed species and evaluate what I really know about each of them. How do I know that one specimen is Pelvetiopsis, when it looks a hell of a lot like a baby Silvetia? I think this unusual self-doubt has to do with post-concussion syndrome. For the past several months I've known that words fly out of my mind as I'm trying to recall them. Why not names as well? At this stage in my recovery I'm supposed to be slowly challenging my brain as well as continuing to rest it. Finding that balance has been tricky. In a few weeks I will have my early morning low tides back. It will be easier for me to drive to intertidal sites then, and I'm going to use tidepooling as therapy. It has been good for my soul in the past, and I hope that it will also be good for my brain in the near future.

A few days ago I was in the intertidal with my friend Brenna. This most recent low tide series followed on the heels of some magnificently large swells and it was iffy whether or not we'd be able to get out to where we wanted to do some collecting. Our first day we went up to Pistachio Beach, just north of Pigeon Point, where the rocky intertidal is bouldery and protected by some large rock outcrops.

Pigeon Point lighthouse, viewed from Pistachio Beach.
27 January 2017
© Allison J. Gong
27 January 2017
© Allison J. Gong

So while the swell was indeed really big, we were pretty well protected in the intertidal. The Seymour Center has a standing order for slugs, hermit crabs, and algae. I was easily able to grab my limit (35) of hermit crabs over the course of the afternoon, and while it's too early in the season for the algae to do much I had my sluggy friend with me to take care of finding nudibranchs, which left me free to let my attention wander as it would.

Codium setchellii at Pistachio Beach.
27 January 2017
© Allison J. Gong

The very first thing to catch my eye as we go out there was the coenocytic green alga Codium setchellii, which I wrote about last time. I've seen and collected C. setchellii from this site before, but don't remember seeing it in such large conspicuous patches. I need to review what I learned about the phenology of various intertidal algae, but here's a thought. Maybe Codium is an early-season species that gets outcompeted by the plethora of fast-growing red algae later in the spring. Red algae were present at Pistachio Beach but not in the lush (and slippery!) abundance that I'll see in, say, June. I'm willing to bet that Codium will be less abundant in the next few months.

Leptasterias sp. at Pigeon Point.
24 April 2016
© Allison J. Gong

In my experience, the six-armed stars of the genus Leptasterias have always been the most abundant sea stars on the stretch of coastline between Franklin Point and Pescadero. Even though they are small--a monstrously ginormous one would be as large as the palm of my hand--they are very numerous in the low-mid intertidal. I've seen them in all sorts of pinks and grays with varying amounts of mottling. Alas, I don't know of any really reliable marks for identifying them to species in the field.

Unlike other familiar stars, such as the various Pisaster species and the common Patiria miniata (bat stars), which reproduce by broadcast spawning their gametes into the water, Leptasterias is a brooder. Males release sperm that is somehow acquired by neighboring females and used to fertilize their eggs. There isn't any space inside a star's body to brood developing embryos, so a Leptasterias female tucks her babies underneath her oral surface and then humps up over them. Leptasterias also humps up when preying on small snails and such, so that particular posture could indicate either feeding or brooding.

Here's a Leptasterias humped up on a rock, photographed last spring:

Leptasterias sp. at Pigeon Point.
5 May 2016
© Allison J. Gong

The only way to tell if a Leptasterias star is feeding or brooding is to pick it up and look at the underside. I did that the other day and saw this:

Brooding Leptasterias sp. star at Pistachio Beach.
27 January 2017
© Allison J. Gong

Those little orange roundish things are developing embryos. While the mother is brooding she cannot feed, and can use only the tips of her arms to hang onto rocks. Don't worry, I replaced this star where I found her and made sure she had attached herself as firmly as possible before I left her. In a few weeks her babies will be big enough to crawl away and she'll be able to feed again.

Looks like the reproductive season for Leptasterias has begun.


The next day Brenna and I went to Davenport, again hoping to get lucky despite another not-so-low tide and big swell.

Davenport Landing Beach and adjacent rocky areas.
© Google Earth

Davenport Landing Beach is a popular sandy beach, with rocky areas to the north and south. The topography of the north end is quite variable, with some large shallow pools and lots of vertical real estate to make the biota very diverse and interesting. The big rocks also provide shelter from the wind, a big plus for the intrepid marine biologist who insists on going out even when it's crazy windy. The southern rocky area is very different, consisting of flat benches that slope gently towards the ocean, with comparatively little vertical terrain. The southern end of the beach is always more easily accessible, which is why I almost always go to the north. But this day the north wasn't going to happen. The winter storms had washed away at least a vertical meter of sand between the rock outcrops. That and the not-so-low tide combined for conditions that made even getting out to the intended collecting site a pretty dodgy affair. So Brenna and I trudged across the beach to the south.

28 January 2017
© Allison J. Gong

Along the way we saw lots of these thumb-sized objects on the beach. At first glance they look like pieces of plastic, but after you see a few of them you realize that they are clearly (ha!) gelatinous things of biological origin. They are slipper-shaped and you can stick them over the ends of your fingers. They have a bumpy texture on the outside and are smooth on the inside.

Any guesses as to what they are?

Pseudoconch of Corolla spectabilis, washed up on Davenport Landing Beach.
28 January 2017
© Allison J. Gong

These funny little things are the pseudoconchs of a pelagic gastropod named Corolla spectabilis. What is a pseudoconch, you ask? If we break down the word into its Greek roots we have 'pseudo-' which means 'false' and 'conch' which means shell. Thus a pseudoconch is a false shell. In this case, 'false' refers to the fact that this shell is both internal (as opposed to external) and uncalcified.

The animal that made these pseudoconchs, Corolla spectabilis, is a type of gastropod called a pteropod (Gk: 'wing-foot'). Pteropods are pelagic relatives of nudibranchs, sea hares, and other marine slugs. They are indeed entirely pelagic, swimming with the elongated lateral edges of their foot. Like almost all pelagic animals, Corolla has a transparent gelatinous body. Even their shell is gelatinous, rather flimsier than most shells, but it serves to provide support for the animal's body as it swims.

You can read more about Corolla spectabilis and see pictures and video here.

Why, you may be wondering, do the pseudoconchs of C. spectabilis end up on the beach, and where is the rest of the animal? The body of Corolla and other pteropods is soft and fragile. When strong storms and heavy swells seep through the area, the water gets churned up and pteropods (and other pelagic animals) get tossed about and shredded. This leaves their pseudoconchs to float on currents until they are either themselves demolished by turbulence or cast upon the beach. Corolla is commonly seen in Monterey Bay, and it is not unusual to find their pseudoconchs on the beaches after a series of severe storms.

Brenna and I were wondering if we could preserve the pseudoconchs somehow. I took several back to the lab and tried to dry them, thinking that they might behave like Velella velella does when dried. Unfortunately, the next day they had shriveled into unrecognizable little blobs of dried snot, and the day after that they had disintegrated completely into piles of dust. Maybe drying them more slowly would work. Something to consider the next time I run across pseudoconchs in the sand.

1

A few days ago I told my friend Brenna that I'd hunt around in the marine lab for a bit of a green alga that she wants to press. I had a pretty good idea of where to look, only the animals I'd seen it on had been removed from the exhibit hall. I asked for and got permission to examine the animals behind the scenes. And fortunately I had remembered correctly, and I was able to pick off some nice clumps of dark green stuff.

Bryopsis corticulans is a filamentous green alga. It grows to about 10 cm in length and is a dark olive color. When emersed it sometimes looks almost black. I've seen it in the intertidal in a few places, where at low tide it resembles nothing so much as a shapeless slime. It's very difficult to see the beauty of organisms when they're out of their natural element, which in this case is water.

B. corticulans emersed during low tide at Mitchell's Cove.
8 June 2016
© Allison J. Gong

But see how pretty it is when submerged?

Bryopsis corticulans
23 January 2017
© Allison J. Gong

One of the reasons I love the algae is their very inscrutability. I enjoy discovering the beauty of organisms that, at first glance, don't look like much. Many of the filamentous algae, both the greens and the reds, have a delicate structure that requires close examination to be appreciated. Fortunately, I have access to microscopes, so close examination is very easy.

The thallus of B. corticulans is relatively simple, consisting of a bipectinate arrangement of filaments.

Apical tip of Bryopsis corticulans.
23 January 2017
© Allison J. Gong

Here's a closer view:

Thallus of Bryopsis corticulans.
23 January 2017
© Allison J. Gong

This is a shot of the main axis and side filaments. The small green blobs are chloroplasts. One thing to notice is that there are no crosswalls separating any of the filaments. That's because the thallus is coenocytic, essentially one large cell with a continuous cytoplasm. Coenocytic cells are common in fungi, the red and green filamentous algae, and a few animals. In animals, coenocytic cells are often referred to as syncytial. They can arise in one of two ways: (1) adjacent cells fuse together; or (2) nuclear replication occurs as usual during normal mitosis but cytokinesis (division of the cytoplasm) does not. However the syncytium arises, it can result in very large cells. Even though B. corticulans itself is a small organism, some algae in the Bryopsidales consist of single cells that can be over 1 meter long!

Sometimes things that appear simple at first glance conceal a deeper complexity when you look more closely.

At the marine lab we have many seawater tanks and tables in various shapes sizes. For my purposes the most useful are the tables. The tables are shallow, about 20 cm deep, but what's nice about them is that water depth can be managed by varying the height of the stand pipe in the drain. I have some critters wandering free within tables and others confined to tanks, colanders, or small screened containers. One of my tables contains the paddle apparatus that stirs jars of babies when I'm raising larvae.

All of these tables are gravity fed from a supply of semi-filtered seawater supply in the ceiling of the building. The seawater flows through some sand filters before being pumped to the top of the building, but is by no means entirely clean. We get all kinds of things recruiting to the surfaces of tables, jars, or anything that sits in a seawater table for more than a few days. Some of the stuff that recruits is a nuisance, such as the spirorbid worms that build tiny calcareous spiral tubes on just about anything and scrape up the knuckles something awful. Other stuff is benign, and more or less ignored until it gets in someone's way. Or until I decide to take a close look at it.

Last year I finally decided to look at some of the red filamentous stuff growing on the bottom and sides of one of the tables. To the naked eye it doesn't look like much, which is why I love having access to a good compound scope. Here's my notebook page from that day:

Observations and sketches of the red alga Antithamnion defectum. date © Allison J. Gong
Observations and sketches of the red alga Antithamnion defectum.
16 June 2015
© Allison J. Gong

Today I took some pictures of the same stuff. It's really pretty and delicate when you see it magnified!

Filaments of A. defectum at 100X magnification. 17 August 2016 © Allison J. Gong
Filaments of A. defectum at 100X magnification.
17 August 2016
© Allison J. Gong
Close-up view of an apical tip of A. defectum at 200X magnification. 17 August 2016 © Allison J. Gong
Close-up view of an apical tip of A. defectum at 200X magnification.
17 August 2016
© Allison J. Gong

I am always gratified when I look back at drawings I made in the past, and find that they still hold true and can be corroborated by photographs. The filamentous reds are so pretty! This is not the best time of year to find sexy algae, and I saw no reproductive structures on any of the filaments I examined. Maybe next spring.

In a different table (the table where the paddle apparatus is, actually) there is some brownish fluffy stuff growing on the bottom surface. I took a look at some of it and noticed right away that the threads didn't have their own inherent structure the way the Antithamnion defectum does. These threads seemed to be sticky, and when I picked up a little piece of the fluff it collapsed into a blob. I had to tease apart the threads in a drop of seawater to make sense of what was going on.

Observations and sketches of benthic diatoms. 17 August 2016 © Allison J. Gong
Observations and sketches of benthic diatoms.
17 August 2016
© Allison J. Gong

These diatoms are really cool! I have no idea which species they are, though. We do have local diatom genera (Thalasionema and Thalassiothrix) in which adjacent cells stick together at their ends to form this kind of wonky chain, but the cells themselves look different. So for now these are unidentified diatoms.

There's no doubt that they are diatoms, though. They have the typical diatom color, a golden-brown that I would name Diatom if I got to name colors, and I could see through the microscope that the cells are enclosed in a silica structure called a frustule.

This is the diatom color:

Chains of benthic diatoms. 17 August 2016 © Allison J. Gong
Chains of benthic diatoms at 100X magnification.
17 August 2016
© Allison J. Gong

At higher magnification the sculpting on the frustule surfaces becomes visible. Unfortunately, at higher magnification you necessarily have less depth of field, so it's more difficult to take photos that show this kind of detail.

Benthic diatoms at 200X magnification. 17 August 2016 © Allison J. Gong
Benthic diatoms at 200X magnification.
17 August 2016
© Allison J. Gong

Some of these cells appear to be doubled. I think one of two things is going here: either the cells simply remain attached to each other by a thin layer of mucilage, or a cell has recently divided and the two cells that are stuck together are the resulting daughter cells. Throughout the growing season diatoms reproduce clonally (each cell divides to produce two genetically identical daughter cells), and their populations can expand very rapidly in response to either natural or artificial nutrient inputs. Because the cells are enclosed by a rigid frustule, however, this clonal replication cannot continue indefinitely. Perhaps diatom reproduction is fodder for another blog post, if people are interested.

But don't those cells look cool?

This week it has been very windy on the coast. As in hope-the-next-gust-doesn't-arrive-while-I-am-still-holding-onto-the-door windy. Seriously, the other day I almost wrenched my shoulder when the wind caught a door I was walking through just as I opened it. I should have braced myself before opening that door. The wind also blows around dust and pollen, exacerbating everybody's spring allergies.

Despite all that, the wind is a good thing because it is the driving force behind coastal upwelling, the oceanographic phenomenon that brings cold, nutrient-rich water from depth to the surface. Upwelled water provides the nutrients that primary producers such as phytoplankton require for photosynthesis. The simple equation is: Sunlight + nutrients = photosynthesis. With the days getting longer as we head toward the summer solstice, this is the perfect time of year to be a phytoplankter. (Note: a phyto- or zooplankter is any creature that lives as plankton)

It takes several days of sustained winds from the north to start upwelling along the coast. I record the temperature in one of my seawater tables every day and keep an eye out for decreases that might indicate upwelling. Given that it's been crazy windy since Sunday (today is Wednesday) I thought today would be a good day to collect a plankton sample and see what's going on.

What did I find? Lots of phytoplankton, right on schedule!

Plankton sample collected from the Santa Cruz Municipal Wharf. 27 April 206 © Allison J. Gong
Plankton sample collected from the Santa Cruz Municipal Wharf.
27 April 206
© Allison J. Gong

Most of these critters are diatoms, of which there were several different types. Diatoms are unicellular algae whose cells are encased in a fancy silica shell called a frustule. More on that later. In Monterey Bay, the first phytoplankters to bloom in the spring are usually diatoms; they can take advantage of upwelled nutrients to fuel rapid asexual division so their populations grow quickly. Photosynthetic creatures from diatoms to redwood trees can perform the biochemical magic of capturing light energy and converting it to chemical energy held in molecules containing fixed carbon (e.g., glucose). Diatom blooms provide food for grazing zooplankters such as copepods and krill. These small animals become food for any number of larger animals, and so on up the food chain, so in every sense possible the phytoplankton are the foundation upon which the entire marine food web is based. Interested in saving the whales? Then you should focus your energies on saving the phytoplankton. Seriously.

The largest object in the photo above is a large protozoan ciliate called a tintinnid. They also live in glass shells, only theirs is called a lorica (L: "body armor"). The tintinnids I see most frequently in tows from the Wharf have a clear goblet-shaped lorica that is entirely transparent. These tintinnids are big, for single-celled creatures, up to over 1 mm in length. That's a lot bigger than some multicellular animals!

Tintinnids are frantic little swimmers. They are heavily ciliated, which means they can swim really fast. The one in the photo was tangled up in the phytoplankton and squashed under a cover slip, which conveniently retarded its motion, but in this video you can see its little cilia beating. I added a few seconds of a different tintinnid swimming solo to the end of the video clip, which will give you a better idea of how they swim.


Here are some other plankters from today's sample:

Photo #1 - Diatoms. The large cell with the spines on both ends is Ditylum brightwellii, one of my favorite scientific names. Chaetoceros cells each have long spines at the corners of the cells. The spines link adjacent cells together, forming chains.

The diatoms Ditylum brightwellii and Chaetoceros spp. from a plankton tow collected from the Santa Cruz Wharf. 27 April 2016 © Allison J. Gong
The diatoms Ditylum brightwellii and Chaetoceros spp. 
27 April 2016
© Allison J. Gong

Photo #2 - Chaetoceros. At least two species of diatoms in the species Chaetoceros.

Chaetoceros spp. 27 April 2016 © Allison J. Gong
Chaetoceros spp.
27 April 2016
© Allison J. Gong

Photo #3 - Chaetoceros debilis(?)This species forms spiral chains.

Chaetoceros debilis (I think). 27 April 2016 © Allison J. Gong
Chaetoceros debilis (I think).
27 April 2016
© Allison J. Gong

Photo #4 - Assorted phytoplankton. In this photo the five roundish cells are the dinoflagellate Protoperidinium. They have two flagella, one in a groove that wraps around the cell and one that trails free. The two button-like cells near the center of the picture are (I think) the diatom Thalassiosira. There are two chains of Chaetoceros debilis and several other chain diatoms. That big opaque vaguely bullet-shaped object to the right of center? That's a fecal pellet, probably from a copepod.

Assorted phytoplankton from the Santa Cruz Wharf. 27 April 2016 © Allison J. Gong
Assorted phytoplankton from the Santa Cruz Wharf.
27 April 2016
© Allison J. Gong

Speaking of copepods, as usual they were very abundant, both as adults and as larvae. In terms of numbers of individuals, copepods are likely the most abundant animals in the sea. Copepods are small crustaceans that feed on phytoplankton and are in turn eaten by many larger animals. In life they have beautifully transparent bodies, allowing us to see the beating heart. See for yourself:

And, finally, about those diatom frustules. As I mentioned above, a diatom's frustule is a sculpted shell made of silica (SiO2). It comes in two parts, an epitheca and a hypotheca, that fit together like the two halves of a petri dish. In fact, I use a petri dish as a frustule model for my marine biology students; it is made of roughly the same substance and demonstrates the size relationship between the epitheca and hypotheca.

The large round centric diatoms best show the structure of the frustule. Here's the best photo I was able to take today of one of the very large centrics, Coscinodiscus:

The centric diatom Coscinodiscus sp. 27 April 2016 © Allison J. Gong
The centric diatom Coscinodiscus sp.
27 April 2016
© Allison J. Gong

I hope that later in the season I can take some better photos of these diatoms. They are so beautiful that I really to do them justice. So much diversity early in the season makes me hope for a good productive season. We'll see!

1

THE ANSWER TO YESTERDAY'S PUZZLE IS . . .

. . . drum roll, please . . .

Microcladia coulteri!

I showed you this:

Mystery red alga, 18 June 2015. © Allison J. Gong
Mystery red alga, 18 June 2015.
© Allison J. Gong

but what you really needed to be certain of the ID was the rest of the photo:

A mystery no more! Microcladia coulteri growing epiphytically on another red alga, 18 June 2015. © Allison J. Gong
A mystery no more! Microcladia coulteri growing epiphytically on another red alga, 18 June 2015.
© Allison J. Gong

Huzzah again for natural history! I love it when natural history provides the answer to a taxonomic or identification question. Sometimes you need to see the organism where it lives in order to understand what it's all about. Quite a lot of modern biology has to do with grinding up organisms and examining their DNA; while I do appreciate the evolutionary and ecological insights these data provide, it's really not my cup of tea. I'd rather spend my time looking at intact organisms than their molecules, and getting outdoors to see them in nature instead of running gels and staring at computer algorithms. As in most other walks of life, it takes many kinds of work to get at the whole picture in ecology, and I am grateful to be able to contribute a little piece to the puzzle.

7

If you visit the California rocky intertidal in the spring or summer, one of the first things you notice will be the macroalgae, or seaweeds. They are incredibly abundant and diverse this time of year, covering just about every bit of rock. In fact, in a landscape sense the only visible organisms are macroalgae and surfgrass:

Algae-covered rocks at Pistachio Beach, 18 June 2015. © Allison J Gong
Algae-covered rocks at Pistachio Beach, 18 June 2015.
© Allison J Gong

Of the three major divisions of algae (the greens, browns, and reds), the red algae are the most diverse. We have several hundred species along the California coast, and while they don't get as big as the kelps (which are brown algae) they display an astonishing assortment of morphologies, colors, and life history complexities. Almost all of the algae in the photo above are reds. The olive-greenish stuff? Yep, those are reds; multiple genera of reds, in fact. The dark brown things? Those are also reds, again representing more than one genus.

Within the incredible diversity of red algae, today I want to focus on two species: Microcladia coulteri and Plocamium pacificum. Both of these algae have delicate branching forms that make beautiful pressings. But despite their apparently similar morphologies, they represent different taxonomic orders and have completely different lifestyles. Let's take a look at how similar they actually are:

Two unrelated but morphologically similar red algae, 18 June 2015. © Allison J. Gong
Two taxonomically unrelated but morphologically similar red algae, 18 June 2015.
© Allison J. Gong

Pretty tough to distinguish, aren't they? The specimen on the left is a bit more robust in comparison, but if you had only one of these in front of you and nothing to compare it to you'd probably be hard-pressed to determine which species it is.

This is where an understanding of natural history becomes invaluable. Since these species are morphologically so similar to each other, an extremely helpful piece of information is where (and how) each one lives. In terms of habitat, these species can be found pretty much right next to each other, so that doesn't help much. However, the surface on which each species grows tells you exactly what you need to know.

The specimen on the left in the photo above is Plocamium pacificum, a member of the taxonomic order Plocamiales. It lives from the mid-low intertidal to the shallow subtidal and is always attached to rocks, as you can see below:

Plocamium pacificum at Davenport Landing, 17 June 2015. © Allison J. Gong
Plocamium pacificum at Davenport Landing, 17 June 2015.
© Allison J. Gong

The specimen on the left was taken from a thallus that was growing on a rock. This means that it is Plocamium pacificum. Now we can label our photograph with one name.

Plocamium pacificum (left) and a mystery look-alike (right), 18 June 2015. © Allison J. Gong
Plocamium pacificum (left) and a mystery look-alike (right), 18 June 2015.
© Allison J. Gong

The specimen on the right was growing as an epiphyte ("on plant") on a large blade of another red alga. This epiphytic lifestyle tells me that it is not Plocamium, but a species in the genus Microcladia in the taxonomic order Ceramiales. When I brought it into the lab to key it out I was able to identify it as Microcladia coulteri. Three cheers for natural history!

Here's a picture of M. coulteri growing on blades of another red alga, Mazzaella sp. See how green the Mazzaella looks? Color isn't the only factor that determines which major group an alga belongs to, and can in fact be quite deceiving!

Microcladia coulteri growing epiphytically on Mazzaella sp. 18 June 2015. © Allison J. Gong
Microcladia coulteri growing epiphytically on Mazzaella sp. at Pistachio Beach, 18 June 2015.
© Allison J. Gong

Finally, we have both specimens identified:

Plocamium pacificum (left) and Microcladia coulteri (right), 18 June 2015. © Allison J. Gong
Plocamium pacificum (left) and Microcladia coulteri (right), 18 June 2015.
© Allison J. Gong

Which is all well and good when you have two specimens in hand that you can compare directly to each other. But what if all you have is this little bit?

Mystery red alga, 18 June 2015. © Allison J. Gong
Mystery red alga, 18 June 2015.
© Allison J. Gong

Would you say this is Plocamium, or Microcladia? What would you base your decision on? And how certain would you be?

Submit answers (with justifications!) in the Comments, and I'll give you the answer tomorrow.

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