Fair is foul, and foul(ing) is fair

Posted on by Allison J. Gong

Next week classes for the Fall semester begin, and this will be my fourth term teaching a marine invertebrate zoology class at this particular institution. I have built this class on a foundation of comparative anatomy and functional morphology; lab activities include dissections (to observe how bodies are put together) and diversity labs (to examine the morphological diversity within major taxa). This year I wanted to include a lab with a broader ecological context. So back in April I hung a box of glass slides from one of the boat slips at the harbor. The idea is that the students in the invert zoo class will examine the slides after they’d been marinating in the ocean for several months and have to figure out what’s growing on them.

The organisms that have and will continue to colonize the slides are members of what is rather disparagingly referred to as a “fouling community.” To be fair, they can be nuisances, fouling docks and pilings, boat hulls, water intake and outflow pipes, and pretty much anything that is left in the water for any significant amount of time. In fact, my friend Adam has a job scraping fouling organisms off the bottoms of boats at the harbor; boat owners either pay to have this done or do it themselves every so often. But to me, these animals and algae form a fascinating ecological community that illustrates many of the principles I teach to my students.

Harbors are some of the places where exotic (i.e., non-native) species are first detected. It is not uncommon for many of the species in a fouling community to have evolved elsewhere and been transported (usually, but not always, unintentionally) to a new location, where they grow swiftly and often out-compete the native species. Obviously, not all species introductions “take” and it’s anybody’s guess how many species were dumped in a new site and failed to stick around. The ones that do take, though, tend to become very prominent.

So, back to my slide box. It was still there, hanging from a string about 2.5 meters below the bottom of the dock. As I pulled it up, I was relieved to see different colors and textures:

Slide box hanging from a floating dock at the harbor. 20 August 2015. © Allison J. Gong
Slide box hanging from a floating dock at the harbor. 20 August 2015.
© Allison J. Gong

Up close, it looked even more promising:

Slide box hanging from a dock at the harbor. 20 August 2015. © Allison J. Gong
Slide box hanging from a dock at the harbor. 20 August 2015.
© Allison J. Gong

Even without knowing what all the differently colored blotches are, you can tell that there’s a lot of stuff growing. I’m not going to dismantle the box until we use it in lab in early November, but I thought it might be worth a closer look. It just so happened that I had both a clean bucket in my car and the foresight to bring it with me onto the dock. This photo shows that the slides themselves are covered with growth:

Slide box hanging from a floating dock at the harbor. 20 August 2015. © Allison J. Gong
Slide box hanging from a floating dock at the harbor. 20 August 2015.
© Allison J. Gong

The red encrusting sheet is the bryozoan Watersipora, probable species subtorquata, an invasive species that is found in harbors all along the California coast. The pale orange blobs are colonies of sea squirts; it is difficult to identify them to species without examination under a microscope. There is also quite a bit of a brown upright branching bryozoan that I think belongs to the genus Bugula.

As an unabashed aficionado of all things hydroid, I’m always very pleased to see certain species of ‘droids at the harbor. They are simply so beautiful that I love looking at them. This is the hydroid Ectopleura crocea. It is common but sporadic and patchy at the harbor, and usually isn’t one of the first species to colonize an area. Its congener, E. marina, occurs in the intertidal; I can find it fairly reliably in a particular pool at Davenport Landing and have occasionally seen it elsewhere.

Ectopleura crocea growing out of a colony of Watersipora subtorquata. 20 August 2015. © Allison J. Gong
The hydroid Ectopleura crocea growing out of a colony of Watersipora subtorquata. 20 August 2015.
© Allison J. Gong

Having reassured myself that my slide box was doing well I took some time to check out other bits of real estate in that area of the dock. I played around with the super-macro setting on my camera, with mixed results. I do now know, though, that it works underwater:

Tentacular array of a serpulid polychaete worm. 20 August 2015. © Allison J. Gong
Tentacular array of a serpulid polychaete worm, with bryozoans in the background. 20 August 2015.
© Allison J. Gong

I found a cooperative barnacle and took some video footage of feeding behavior. Barnacles are strange crustaceans that lie on their backs and kick their modified thoracic appendages through the water to capture small particles. What a weird way to make a living. But the animal is always right, and barnacles can be quite efficient at clearing water.

And, finally, does anybody know the source for the title of this post? Answer in the comments section, please!

Falling in love

Posted on by Allison J. Gong

Today Scott and I gathered all of our tiny Pisaster stars and assigned them to food treatments. We’re not doing a feeding experiment per se but have the goal of getting these juveniles to grow, and to do that we need to figure out what they eat when they’re this small. Nobody knows, or at least we haven’t been able to find any literature on the subject, so we’re trying a shotgun approach and offering them several different items.

One of the food items is the bryozoan Membranipora membranacea, which I wrote about yesterday. Scott picked up some fresh kelp yesterday afternoon and several of the blades were encrusted with Membranipora. We thought these new colonies might be a more appetizing meal for the stars. We knew we’d have to remove any of the Corambe slugs that might be feasting on the bryozoan, so I put a piece under the scope. And. . . whoa. . .

So lively! The bryozoan colony was unbelievably gorgeous. All of the zooids were active and reactive, with lophophores extended and tentacles flicking. This video is taken in real-time. Note how the zooids act independently, but REact as a group. They share enough neural apparatus that stimuli are perceived almost instantaneously by all the zooids in a region.

One of the things I love about colonial and clonal animals is that they upend our preconceived notions of what an individual is. In an animal like a bryozoan, what is the individual? Is it the zooid, possessing its own feeding apparatus that it employs independently from the other zooids to which it is genetically identical? Or is it the colony, consisting of many zooids? And what role does genetic identity play in the definition of individual? How much integration among units is required before they collectively form what we call a body? So many fascinating questions to ponder!

Anyway, Scott had the brilliant idea of gut-loading the bryozoans before feeding them to the stars, so I fetched a couple mL of the green alga Dunaliella tertiolecta that we have growing in pure culture and gave them a few drops, just to see what the zooids would do.

Wow.

This video is also shot in real-time. The zooids are kind of just doing their thing, but when I add the drop of algae about halfway through the video they kick into high gear and go hyper. I didn’t expect such an energetic response.

It is difficult to convey just how mesmerizing these bryozoans are. They are a fantastic example of animals that are completely overlooked even by many biologists because to understand and appreciate them you need to look at them under a microscope. Without magnification they really don’t look like much, just whitish gray crusts growing on kelp blades. But the microscope opens up a view into their lives and shows us how complex and beautiful they are. Sometimes the most amazing and gorgeous things are the ones you can’t see with the naked eye. And that is exactly what I love about them.

The Enemy of the State

Posted on by Allison J. Gong

I came of age, in an academic sense, working as a technician in a lab where the research focused on colonial hydroids. The other tech in the lab, Brenda, and I would get sent out to collect hydroids, then spend another day or so picking the predatory nudibranchs off the colonies. The PI of the lab called nudibranchs “the enemies of the state” and they really did have a way of showing up out of nowhere and then eating a hydroid colony down to nothing. It was rather amazing, actually. Brenda and I would swear we’d picked off all the nudibranchs, and more would show up the next day. This same PI had another saying:  “For every hydroid there’s a nudibranch that lives on it, eats it, and looks just like it.”

Case in point. Today Scott and I were examining not hydroids, but bryozoans, which are a completely unrelated type of colonial animal. We want to see if our tiny juvenile Pisaster stars will eat the bryozoan. It didn’t take long to see this:

The nudibranch Corambe sp. on the encrusting bryozoan Membranipora membranacea. 13 August 2015. © Allison J. Gong
The nudibranch Corambe sp. on the encrusting bryozoan Membranipora membranacea. 13 August 2015.
© Allison J. Gong

A bryozoan colony consists of many units, called zooids, that are connected in some way to form a functioning larger body. The brick-like white structures in the above photo are the zooecia, or “houses” of the bryozoan zooids. The round object near the center of the photo with wavy white lines is the nudibranch Corambe. The white lines on the back of the slug make it blend in very nicely with the bryozoan on which it feeds, and break up the outline of the body to disguise its size; how can you determine how big something is if you can’t see its edges? This slug is probably 2-3 mm long. As with most creatures this size and so effectively cryptic, it is very easy to overlook the slugs and never see them; however, once you have a good search image they become much more conspicuous and you find them everywhere. Search images are great things.

It’s also easier to see something if it’s moving, and it turns out that this slug can move pretty fast:

The voice that you hear is Scott’s.

Corambe lives primarily on Membranipora and eats it. Membranipora responds to this predation by forming spines along the edges of the colony; the spines make it more difficult for the nudibranch to crawl around. This kind of response is called an inducible defense. The same thing occurs when plants begin to produce noxious chemicals after being munched on by an insect herbivore. Scott and I will set up some feeding treatments for our juvenile stars and Membranipora will be one of the courses served, so we were both glad to see that despite all the slugs we picked off there were still lots of viable zooids remaining.

Here’s what a bryozoan is all about. Each zooecium forms the outer casing of one zooid. The zooecium itself is non-living but contains the living part. In Membranipora all of the zooids in the colony are the same, and each one possesses a ciliated tentacular crown called a lophophore. The cilia on the tentacles produce a current that directs food particles to the mouth, which is located at the base of the lophophore. In this video you can see particles moving in the current, and one zooid accidentally sucks in a glom of stuff that is too big. Watch how it tries to get rid of the piece it doesn’t want.

See how the individual tentacles sort of bend and then straighten up? I call that tentacle flicking.

If you spend a couple of hours looking at something through a microscope it’s inevitable that you’ll see something different and new. In one of the bryozoan pieces I saw two little pink blobs in an otherwise empty zooecium. It looked like they were moving, so I zoomed in and saw that they looked like shmoos. “Shmoo” has become my term for any undifferentiated, unsegmented, worm-like thing that I can’t identify. These pink shmoos were definitely moving, and here’s the video to prove it:

That little squeal at the end of the video? That’s me. I was delighted to see that the shmoos have two eyes and turn somersaults. I still have no idea what they are, and I’m totally okay with that. It’s enough to know that they exist.

A marine biologist goes to the mountains

Posted on by Allison J. Gong

This past weekend I attended a family reunion at South Lake Tahoe. It had been several years since the previous reunion for this side of the family, and it was wonderful seeing almost all of my cousins and their various offspring, plus aunts and uncles, in a glorious setting. All good things must come to an end, though, and finally we all left Tahoe to return to our regular lives.

On our way back I stopped at the Taylor Creek Visitor Center and did a short hike. The Rainbow Trail is a 1/2-mile loop that winds through forest, meadow, and riparian habitats and includes the stream profile chamber, which shows a bit of the natural creek where kokanee salmon migrate in the fall. It’s a beautiful spot to walk around a bit and get a last nature fix before dealing with traffic and the drive home. Some day I’ll time a visit to coincide with the salmon run. “Salmon run? What salmon run?” you may wonder. Well, read on.

Taylor Creek flows northward about 3.5 km from Fallen Leaf Lake into Lake Tahoe. It forms part of the wetland that protects Tahoe from runoff and silt, helping to maintain the clarity of the lake. As with most of the land in the Tahoe basin, Taylor Creek has been modified by human activity:  the streambed itself has been altered by road development, and the introduction of non-native species such as bullfrogs threatens populations of native species. Still, it is a remarkably beautiful place.

Meadow at Taylor Creek, South Lake Tahoe. 9 August 2015. © Allison J. Gong
Meadow at Taylor Creek, South Lake Tahoe
9 August 2015
© Allison J. Gong
Taylor Creek, South Lake Tahoe. 9 August 2015. © Allison J. Gong
Taylor Creek, South Lake Tahoe
9 August 2015
© Allison J. Gong

Beavers are also continually changing the course of the creek. They fell trees and construct dams that redirect water flow and create still ponds upstream of the dam. In the summer it is not uncommon to see dams and other evidence of beaver activity. Of course, the dams impede the movement of most fish up and down the creek.

Beaver dam on Taylor Creek, South Lake Tahoe. 9 August 2015. © Allison J. Gong
Beaver dam on Taylor Creek, South Lake Tahoe
9 August 2015
© Allison J. Gong
Tree almost felled by beavers at Taylor Creek, South Lake Tahoe. 9 August 2015. © Allison J. Gong
Beaver-gnawed tree at Taylor Creek, South Lake Tahoe
9 August 2015
© Allison J. Gong

One of the more noteworthy fish living in Taylor Creek is the kokanee salmon, a landlocked version of the sockeye (Oncorhynchus nerka) that is one of five species of salmon in the northeastern Pacific Ocean. Whereas most eastern Pacific salmon are anadromous, living their adult lives at sea but returning to freshwater rivers to reproduce, the kokanee spend their entire lives in freshwater. Kokanee were introduced into Lake Tahoe in the 1940s and have since become a popular game fish. In the fall, they migrate from Lake Tahoe into Taylor Creek to spawn. Beaver dams would block the kokanee’s return to their spawning grounds, so every year the U.S. Fish and Wildlife Service demolishes the dams to allow the salmon access to the creek; this action also increases runoff into Lake Tahoe and decreases the total area of wetlands in the region, both of which have a detrimental effect on the lake’s clarity. The net result is spawning habitat for a non-native species, the kokanee, at the cost of decreased lake clarity and (arguably) damage to a native species, the beaver. We humans seem to be unrelentingly amenable to making such trade-offs. I wonder where that will get us in the long run.

For most visitors, the highlight of the Rainbow Trail is the stream profile chamber. This little chamber has displays about the life cycle of the kokanee salmon, the seasons of Taylor Creek, and a window into the stream itself. At this time of year the only fish inhabitants were Lahontan redsides (Richardsonius egregius), minnow-like fishes about the length of my hand or a bit shorter. The kokanee, wearing their brilliant mating costumes, will pass through the stream in October.

I did take some video footage of the redsides swimming in the chamber, bathed in the sunlight that filters through the upper layers of water. The bird and other animal sounds you hear are recordings that are played in the chamber.

Returning to the outdoors, I hiked through more meadows and forest, stopping frequently to look and listen for birds. This summer, despite drought conditions throughout California, the Tahoe region has gotten enough rain for wildflowers (and mosquitos) to persist; I walked through fields of goldenrod, blooming skunk cabbage, lupine, and Queen Anne’s lace. The aspen trees (Populus tremuloides) haven’t started changing color yet, but walking through them I could hear the rustle of their leaves, which is one of the characteristic sounds of northern California high-altitude Sierra Nevada forests.

Aspen grove at Taylor Creek, South Lake Tahoe. 9 August 2015. © Allison J. Gong
Aspen grove at Taylor Creek, South Lake Tahoe
9 August 2015
© Allison J. Gong

In the autumn the aspens will change color and blanket the high Sierra in golds and oranges–yet another reason to return to the Tahoe area in the fall!

You are what you eat, part the second

Posted on by Allison J. Gong

Two months ago now I gave my juvenile sea urchins a job. It’s the kind of job they’re perfectly suited for:  eating algae. I measured them all and randomly divvied them up into three food treatments. One group remains on the pink coralline alga they’d all been eating once they graduated from a diet of scum, one group gets to eat the soft green alga Ulva sp., and the third group is eating the kelp Macrocystis pyrifera. I fully expected that the urchins on coralline algae would grow much more slowly and experience higher mortality than the other groups. And now I have data to validate my intuition!

Test diameter of juvenile sea urchins (Strongylocentrotus purpuratus) as a function of diet. 3 August 2015. © Allison J. Gong
Test diameter of juvenile sea urchins (Strongylocentrotus purpuratus) as a function of diet. 3 August 2015.
© Allison J. Gong

It has been clear from the get-go that the Ulva and Macrocystis urchins are growing faster than the poor guys relegated to coralline algae. The coralline urchins are hanging in there, though, and are even growing a bit. They are also dying, a lot.

Population sizes of juvenile sea urchins (Strongylocentrotus purpuratus) as a function of diet. 3 August 2015. © Allison J. Gong
Population sizes of juvenile sea urchins (Strongylocentrotus purpuratus) as a function of diet. 3 August 2015.
© Allison J. Gong

During the first month of the experiment I was surprised to see the high attrition rate of urchins eating Macrocystis. I think these early deaths were due to the fact that Macrocystis, once it starts to go bad, goes bad fast. Even with daily water changes to rinse out the poop, the Macrocystis bowl tended to get dirty faster than the others, so poor water quality may have killed the urchins. The copious slime from the Macrocystis itself doesn’t help, either. Eventually I will be able to graduate the urchins to containers that will allow flow-through water, but for now most of them are too small to be kept in screened containers because they would escape through the mesh.

Overall, the Ulva urchins seem to be the happiest. I haven’t lost any this past month and they eat and poop a lot. These individuals have the good fortune that Ulva doesn’t foul the water as quickly as Macrocystis does. They are extraordinarily beautiful, too, and are becoming much more colorful:

Juvenile sea urchin (Strongylocentrotus purpuratus), age 196 days. 3 August 2015. © Allison J. Gong
Juvenile sea urchin (Strongylocentrotus purpuratus), age 196 days. 3 August 2015.
© Allison J. Gong

I’ve always wondered about the biochemical magic that allows this species of sea urchin to eat algae (primarily kelps, but also some red and green algae) and end up so unabashedly purple as they grow to adulthood. I know from experience in the intertidal that juveniles of S. purpuratus usually go through a green stage when they’re in the 1-2 cm size range, before they become purple. And once they’re purple, they stay purple. Part of the reason I wanted to do this feeding experiment is to see how the juvenile diet affects color of the animal. These urchins are all from the same mating, so they are full siblings. Presumably there would be some color variation even among a cohort of full-sibs, but if I can distinguish differences between urchins eating Ulva and urchins eating Macrocystis, then perhaps these would be at least partly due to diet?

The difficulty is in photographing individual urchins under the same lighting and background conditions so that color can be somewhat objectively registered. I’m going to have to become a much better photographer, and the urchins are going to have to be more willing to sit still and pose for me. In the meantime, it is easier to compare overall color between the two groups, rather than individual urchins. Looking at the two bowls side-by-side, I get a better feel for the gestalt of each group; can you see the difference? Before you read the caption, can you guess which is the Ulva group and which is the Macrocystis group?

Juvenile sea urchins (Strongylocentrotus purpuratus), age 196 days. Urchins on the left are eating the green alga Ulva; urchins on the right are eating the kelp Macrocystis. 3 August 2015. © Allison J. Gong
Juvenile sea urchins (Strongylocentrotus purpuratus), age 196 days. Urchins on the left are eating the green alga Ulva; urchins on the right are eating the kelp Macrocystis. 3 August 2015.
© Allison J. Gong

To my admittedly very subjective eye, the urchins on the left have more dark pigment and the ones on the right have a more overall golden color. The golden color makes sense because Macrocystis is golden in color (even though taxonomically it is considered a brown alga). But the darker purple in the urchins eating green algae? That makes less sense to me. In any case, I’ll have to wait and see how the color develops in both groups of urchins. I suspect that in the long run they’ll all end up purple, because that’s what they do in the field, but they may take different routes getting there. Stay tuned!

Pop quiz!

Posted on by Allison J. Gong

Okay, what are these? Extra-credit: Who made them?

Mystery object!
Mystery objects!
  • Clue #1:  Each of those little pink balls is about 80 µm in diameter.
  • Clue #2:  These objects appeared in the last 24 hours.
  • Clue #3:  Color matters!

If you’ve been reading my blog posts for the past few months, you’ve seen everything you need to answer both questions.

Respond in the Comments section, please!

More unusual sightings, and some underwater experiments

Posted on by Allison J. Gong

In defiance of post-nasal drip and an ominous tickle at the back of my throat, I got up early again this morning and went out on the low tide. I skipped yesterday’s low tide in favor of getting a little more sleep, thinking that it would help me fight off this incipient summer cold, but I didn’t want to miss two of the three intertidal trips I had planned for this weekend. So I made the quick drive up to Davenport Landing, where low tide was at 06:4o.

The first thing I noticed when I got down to the beach was that the algae have started piling up. There were drifts that I sank into almost knee-deep. Fortunately they hadn’t really started decomposing yet, so the smell wasn’t too bad. That will change if it stays warm and the high tides don’t wash any of the algal detritus back out to sea.

Looking back at Davenport Landing beach, from the north. 2 August 2015. © Allison J. Gong
Looking over piles of algal detritus towards Davenport Landing beach, from the north. 2 August 2015.
© Allison J. Gong

It’s treacherous stuff, that algal duff. It covers up deep holes and slippery rocks, so each footstep becomes an adventure. Because it has been so warm I had considered going out in shorts and surf booties, but more than once this morning I was glad to be wearing my hip boots.

It was a busy day for nemertean worms. Nemerteans are unsegmented, slimy, predatory worms that feed by shooting out a proboscis and wrapping it around prey. In some nemerteans the proboscis is armed with a stylet that injects toxins to help immobilize prey, which are often small polychaete (segmented) worms. Nemerteans are not uncommon, but are often inconspicuous and easily overlooked. None of the ones that I saw today were actively hunting.

Nemertean worm (Paranemertes peregrina) at Davenport Landing, 2 August 2015. © Allison J. Gong
Nemertean worm (Paranemertes peregrina) at Davenport Landing, 2 August 2015.
© Allison J. Gong

As you can see, the body of this worm is not segmented. However, it has the same body wall musculature that you’d find in the polychaetes, which are the segmented marine worms. It uses the muscles to alternately contract and elongate the body and move forward. In most nemerteans neither the head nor the tail end is particularly distinguishable, but in worms you can usually tell the anterior (head) end by the direction of locomotion. Here’s a video:

Continuing to play with the ‘microscope’ setting on my camera, I took this picture of a chiton (Mopalia muscosa):

Mopalia muscosa at Davenport Landing, 2 August 2015. © Allison J. Gong
Mopalia muscosa at Davenport Landing, 2 August 2015.
© Allison J. Gong

I’m still learning how to make that compromise between super-macro and depth of field on this setting. The chiton in the above photo is about 4 cm long so I wasn’t zoomed in terribly far, and I like how it is in focus but some of the other critters are as well.

On the reef to the north of Davenport Landing beach there’s a large pool that gets to a bit more than knee deep on me, and is cut off from the ocean during low tide. This pool has proven to be a great place to practice my underwater picture taking. The past couple of times I’ve come out here I’ve seen schools of surfperches swimming in this pool. The school contains large individuals (about as long as my hand) and smaller ones that I think are the babies of the big ones. I haven’t been able to catch one–for some reason I’ve never included a dipnet in my collecting gear, preferring to catch sculpins with my hands–but I think they are shiner surfperches (Cymatogaster aggregata).

Before trying to photograph the fishes underwater, I shot some video from above:

It turns out that photographing fish underwater isn’t as easy as I thought it might be. Surfperches are pretty skittish and I couldn’t get as close to them as I wanted. However if I stood still for a minute or so they forgot about me and would resume their normal behavior. In the meantime I did sort-of-accidentally take some cool pictures of the pool from below the surface.

Large tidepool at Davenport Landing, 2 August 2015. © Allison J. Gong
Large tidepool at Davenport Landing, 2 August 2015.
© Allison J. Gong
Large tidepool at Davenport Landing, 2 August 2015. © Allison J. Gong
Large tidepool at Davenport Landing, 2 August 2015.
© Allison J. Gong

And finally, fish!

Shiner surfperches in large tidepool at Davenport Landing, 2 August 2015. © Allison J. Gong
Shiner surfperches (Cymatogaster aggregata) in large tidepool at Davenport Landing, 2 August 2015.
© Allison J. Gong

Last, but certainly not least, in this same large pool I found several anemones. The most brightly colored are the Anthopleura artemisia. I love how their tentacles can be such a vibrant translucent orange or purple, or the oral disc can have that deep saturated red color.

Anthopleura artemisia at Davenport Landing, 2 August 2015. © Allison J. Gong
Anthopleura artemisia at Davenport Landing, 2 August 2015.
© Allison J. Gong
Anthopleura artemisia at Davenport Landing, 2 August 2015. © Allison J. Gong
Anthopleura artemisia at Davenport Landing, 2 August 2015.
© Allison J. Gong

Hard to believe that these animals are the same species, isn’t it? Then again, to an alien scientist studying humans it might be hard to believe that a Viking, an Australian aboriginal and I (an Asian-American) are the same species. It’s all simply a matter of perspective.

Farewell, Franklin Point!

Posted on by Allison J. Gong

Today I made what is likely my last trip to Franklin Point for several months. Tonight’s blue moon brings us the last of the good low tide series until the end of October. For me, a “good” tide series is one in which the low lows occur during daylight hours and are below the zero mean low low water (MLLW) height. Now that we’re more than a month beyond the summer solstice we are losing daylight at an almost-noticeable rate; and for reasons I’ve never been able to understand, at this time of year the spring tides (when we have the highest highs and lowest lows) get dampened out so the magnitude of the tidal exchange is less.

My plan is to take full advantage of this last tide series. This morning I was up well before dawn to catch the low at 05:19. For the past day or so the swell has been coming from the southwest, which is unusual, with unpredictable waves and surges. Plus, the sand has been piling up on the beach for the last month, and only the tops of many of the rocks were visible. This is a typical pattern:  Sand accumulates on beaches during the calm summer/autumn months, then gets washed away during the winter storms. If the predicted El Niño that everyone is talking about brings the storms that California desperately needs, we could end up with a dramatically different coastline next summer.

But in the meantime, I wanted to continue testing my new camera. Today was the first day I’ve had it in the field and I was particularly interested in seeing how well the ‘microscope’ setting, which is a super-macro setting, would do underwater. The verdict:  Pretty dang well!

Case in point. This is a shot of a swarm(?) of the sand crab Emerita analoga, in a shallow pool. I saw many thousands of them when I was here two weeks ago, and this morning they were still there. Anyway, as expected the ‘microscope’ setting on the camera has a very narrow depth of field, but I still think this photo is cool. That long feathery object in the lower right hand corner is the second antenna of one of the crabs that’s not actually in the photo.

Sand crabs (Emerita analoga) in a small tidepool at Franklin Point, 31 July 2015. © Allison J. Gong
Sand crabs (Emerita analoga) in a small tidepool at Franklin Point, 31 July 2015.
© Allison J. Gong

To give you a sense of scale, these crabs are about 1 cm long. And that second antenna is about as long as the rest of the body. The crabs swivel their second antennae around and catch food particles on those fine side branches.

The camera did a great job with this close-up shot of the nudibranch Dirona picta. I saw four of these slugs in one area.

The nudibranch Dirona picta at Franklin Point, 31 July 2015. © Allison J. Gong
The nudibranch Dirona picta at Franklin Point, 31 July 2015.
© Allison J. Gong

What makes this nudibranch unusual is the warts on the cerata (the inflated dorsal projections). This species feeds on bryozoans. I didn’t see any egg cases, but where there are slugs there are always eggs (and vice versa, I suppose) so I must have overlooked them.

Today was the second trip in a row out to Franklin Point that I’ve seen brittle stars. This morning I saw three, two of which were pretty mangled. This is the most intact one, and it is beautiful:

The brittle star Ophiothrix spiculata in a tidepool at Franklin Point, 31 July 2015. © Allison J. Gong
The brittle star Ophiothrix spiculata in a tidepool at Franklin Point, 31 July 2015.
© Allison J. Gong

Armtip-to-armtip, this little guy measured about 1.5 cm. Although brittle stars share a star shape with their kin the sea stars, they locomote in an entirely different way. Whereas sea stars walk on hundreds or thousands of suckered tube feet, brittle stars use their arms to push and pull themselves along. They move much more quickly than sea stars. See here:

And, my favorite photographic model of the intertidal, the sea anemone Anthopleura sola. Here’s the entire animal:

The sea anemone Anthopleura sola at Franklin Point, 31 July 2015. © Allison J. Gong
The sea anemone Anthopleura sola at Franklin Point, 31 July 2015.
© Allison J. Gong

And here’s a close-up of the mouth. I took this shot from a distance of about 8 cm. I suppose I could have just cropped and zoomed in on the above photo, but where’s the fun in that when you can do this?

Close-up of the oral disc of Anthopleura sola at Franklin Point, 31 July 2015. © Allison J. Gong
Close-up of the oral disc of Anthopleura sola at Franklin Point, 31 July 2015.
© Allison J. Gong

On the hike back over the dunes I stopped to listen and look around and was rewarded with this sighting of a doe in the grass. She may or may not have had fawns with her, but I didn’t see them. Of the several photos I took of her, this is my favorite because even though it’s a little washed out you can see the Pigeon Point lighthouse very faintly in the background.

© Allison J. Gong
© Allison J. Gong

So that’s it for now. The next time I visit Franklin Point the low tide will be in the afternoon and I will be fighting both darkness and wind. It will still be entirely worth it, though.

Tomorrow I’m going up the coast a bit more, to just north of Pigeon Point. It will probably be my last trip to this particular site, also. I hope to come back with some snails (for my upcoming class) and pictures (to share).

Nature’s air conditioning

Posted on by Allison J. Gong

While much of California’s interior swelters under abominable heat this week, here on the coast we are blessed by the presence of the marine layer, which often brings cooling fog. It was drizzling when I got up this morning, and although the sun did make brief appearances the air remained refreshingly cool. And right now, on the antepenultimate day of July, I’m wearing a jacket!

marine-layer-day-300

The marine layer is an inversion layer in the lower atmosphere that forms when a warm, moist air mass sits over a large body of water. The water cools the lower portion of the air mass, and since cool air holds less moisture than warm air, water condenses out as fog. The term “inversion layer” refers to the fact that temperature within the air mass increases with altitude, which is the opposite of the normal temperature-altitude relationship. In California the marine layer is blocked by mountains such as the Coast Range, but flows through gaps in the mountains to bring a bit of cooling relief to some lucky areas. When I was living in Davis, CA we used to pray for the arrival of what we called delta breezes to take edge off the heat in the evenings.

Where I live now, the marine layer is thickest from May-July. These are typically our foggiest months, with the daily weather following the pattern in the diagram above. This is my favorite weather of the year:  A cool foggy morning with the fog clearing to the coast by mid-day, a few hours of bright sunshine, and the fog returning in the late afternoon or early evening. A foggy morning pretty much guarantees that it won’t get too hot later in the day, but I’ll also get some sun.

Marine layer, visible as fog over Monterey Bay, 29 July 2015. © Allison J. Gong
Marine layer, visible as fog over Monterey Bay
29 July 2015
© Allison J. Gong

Of course, El Niño changes everything, and it appears that we’re heading into a strong one. El Niño causes, among other things, a warming of the water in the eastern Pacific. This means that the temperature difference between the ocean and the overlying air mass is decreased, resulting in a less robust marine layer. At ground level, this manifests as less fog and hotter days. It seems to me that we’ve had fewer foggy days this year compared to what I’m used to, corresponding to the lack of upwelling that is also a hallmark of El Niño.

Today, however, nature’s air conditioning was operating again and I, for one, am happy about that.

Life in the sea

Posted on by Allison J. Gong

This morning I collected another plankton sample from the end of the Santa Cruz Municipal Wharf, equipped this time with a 53-µm net used to collect phytoplankton. Phytos, as we refer to them, are the (mostly) unicellular photosynthetic organisms that make up the bottom of the pelagic trophic web. In a nutshell, they are the food that sustains all other organisms in the pelagic realm; i.e., every creature that lives away from the sea floor. Without phytoplankton, we would essentially have zero life in the sea. Think about that the next time you see a “Save the Whales” sign:  To save the whales, maybe we should work harder at saving the phytoplankton.

The water is still that pretty shade of aquamarine, but to the naked eye it seemed a little less opaque than it was a week ago. One thing I did see immediately was a huge school of bait fish, and a gaggle of teenage boys trying to catch them with their fishing poles. The school was pretty impressive; the teenage boys, not so much. But they get props for trying.

School of bait fish on the east side of the Santa Cruz Municipal Wharf, 24 July 2015. © Allison J. Gong
School of bait fish on the east side of the Santa Cruz Municipal Wharf
24 July 2015
© Allison J. Gong

I find schooling behavior fascinating. I love how the amorphous blob moves through the water, avoiding predators and obstacles (including my plankton net) alike with apparently little effort. Even the sea lions swimming around the pilings didn’t generate much of a response from the fish except a lazy move out of the way.

The arrival of bait fish makes me wonder if whales will follow.

Back in the lab I looked at what I had caught. As expected there were very few large animals, but quite a lot of interesting phytoplankters and small zooplankters. Here’s a sort of representative sample:

Marine phytoplankton collected from Santa Cruz Municipal Wharf, 24 July 2015. Key: (a) Radiolarian, a type of amoeba; (b) Protoperidinium, a dinoflagellate; (c) Ceratium, a dinoflagellate; (d) unidentified golden cells. © Allison J. Gong
Marine phytoplankton collected from Santa Cruz Municipal Wharf, 24 July 2015.
Key: (a) radiolarian, a type of amoeba; (b) Protoperidinium, a dinoflagellate; (c) Ceratium, a dinoflagellate; (d) unidentified golden cells.
© Allison J. Gong

The coolest thing I found in today’s sample was a silicoflagellate. I think in all my years of observing local marine plankton I’ve seen silicoflagellates only once before today, when I was in graduate school. Not much is known about their biology, but their siliceous fossils have been pretty well studied.

Silicoflagellate in plankton sample collected from Santa Cruz Municipal Wharf, 24 July 2015. © Allison J. Gong
Silicoflagellate in plankton sample collected from Santa Cruz Municipal Wharf, 24 July 2015.
© Allison J. Gong

Silicoflagellates are flat unicellular phytoplankters with two flagella that they use to swim. You can sort of see one flagellum sticking out at about 10:30 on the cell perimeter. You can see it better in this video clip (apologies for the background music). Watch as the flagellum wiggles and pushes the cell around.

Did you see the flagellum? How cool is that? Pretty fancy for a simple unicell, isn’t it?