Author: Allison J. Gong

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?

A star is born!

Posted on by Allison J. Gong

I’m sorry. I had to go there. You didn’t really expect me not to, did you?

The reason, of course, is that today we got our first settled and metamorphosed Pisaster stars! We were doing our normal Monday water change when I noticed a teensy orange speck on the bottom of one of the jars. I used my beat-up old paintbrush to remove the tiny dot to a dish, put it under the dissecting scope, and saw this:

Metamorphosing ochre star (Pisaster ochraceus), age 48 days. 20 July 2015. © Allison J. Gong
Metamorphosing ochre star (Pisaster ochraceus), age 48 days
20 July 2015
© Allison J. Gong

From this picture it’s a little hard to see what’s going on. The entire body has contracted a lot, from a 2.5-mm larva to about 1/4 of the original size as a 600-µm juvenile, and become much more opaque. There are tube feet and spines as well as some remnants of larval body (the soft bits at the bottom of the animal) at this in-between larvenile stage.

Here’s a picture of a fully metamorphosed little star:

Newly metamorphosed ochre star (Pisaster ochraceus), age 48 days. 20 July 2015. © Allison J. Gong
Newly metamorphosed ochre star (Pisaster ochraceus), age 48 days
20 July 2015
© Allison J. Gong

I expect we’ll be seeing more tiny orange dots on the bottoms and sides of the jars in the next several weeks. At some point we will have to figure out what they eat and provide it for them. But at least we know we’re able to get them through the larval phase.

Just for kicks, here are some pictures of where we grow the larvae and how we do the twice-weekly water changes.

Larval culturing paddle table. © Allison J. Gong
Larval culturing paddle table.
© Allison J. Gong
Step 1: We pour the larvae into a filter to concentrate them into a smaller volume of water. Then we can wash or rinse the jar. © Allison J. Gong
Step 1: We pour the larvae into a filter to concentrate them into a smaller volume of water. Then we can wash or rinse the jar.
© Allison J. Gong
Steps 2 and 3: We use a turkey baster to transfer most of the larvae from the filter into a jar of clean water. The final step is to turn the filter over and wash the last larvae into the jar. © Allison J. Gong
Steps 2 and 3: We use a turkey baster to transfer most of the larvae from the filter into a jar of clean water. The final step is to turn the filter over and wash the last larvae into the jar. Then we fill up the jar and resume the stirring.
© Allison J. Gong

An update on other matters:

Today is the six-month birthday of my baby urchins! Six months ago to the day these little guys were zygotes, and six-months-plus-one-day ago their parents were roaming the intertidal. They grow up so fast!

Juvenile sea urchin (Strongylocentrotus purpuratus), age 6 months. 20 July 2015. © Allison J. Gong
Juvenile sea urchin (Strongylocentrotus purpuratus), age 6 months
20 July 2015
© Allison J. Gong

And lastly, that little shmoo-type thing that I found in the plankton yesterday has revealed itself to be. . . an anemone!

One of the things I like best about cnidarians is the beautiful transparency of their bodies. I love how you can see fluid circulating through the tentacles. Gorgeous, isn’t it?

I go on a treasure hunt

Posted on by Allison J. Gong

California is being slammed by a very intense El Niño event, and the effects are being felt up and down the coast. Seawater temperatures here in Santa Cruz have been in the 15-16°C since late May, and in the past week have shot up to 18.5°C. While Californians have their fingers crossed that El Niño will bring drought-relieving rain this winter, I’m also concerned about how it is affecting marine life.

On a whim, I decided this morning to take a look at what’s going on in the local marine plankton. I grabbed a plankton net with a mesh size of 165 µm (we call a net with this mesh size a “zooplankton net”) and headed out to the end of the wharf. The water is a milky greenish aqua color, which the Monterey Bay Aquarium says is due to a bloom of a type of phytoplankton called coccolithophores. I’ve never seen living coccolithophores before, as they are usually not common in Monterey Bay. Besides, they are really small and don’t often get caught in the type of plankton net that I deploy. So while I didn’t really think I’d catch any coccolithophores, it is always fun looking at plankton. Given the warm water and lack of productive upwelling this season, I didn’t know what to expect.

Water under the Santa Cruz Municipal Wharf, 19 July 2015. © Allison J. Gong
Water under the Santa Cruz Municipal Wharf
19 July 2015
© Allison J. Gong
Water on the west side of the Santa Cruz Municipal Wharf, 19 July 2015. © Allison J. Gong
Water on the west side of the Santa Cruz Municipal Wharf
9 July 2015
© Allison J. Gong

When the water around here is this color, it usually means that phytoplankton are not very abundant. And sure enough, when I pulled up the net it wasn’t very brown and didn’t have that certain smell of diatoms, which were extremely thick earlier in the season. In fact, earlier this month the Central and Northern California Ocean Observing System (CeNCOOS) detected high levels of both the toxin domoic acid and the diatom, Pseudo-nitzschia, that produces it. But in today’s sample I didn’t see a single diatom and only a few dinoflagellates. It’s conditions like this–warm, nutrient-depleted water–that the coccolithophores like.

One of the best things about examining a plankton sample is that you never know what you’ll find. Despite the lack of phytoplankton in the water, my sample was chock full of interesting zooplankters. In addition to the usual copepods (probably the most abundant animals in the world) and their larvae, there were larval polychaete worms and molluscs, medusae of multiple species, and assorted other goodies.

Goodies #1 and #2:

A metamorphosing sea urchin (left) and larval polychaete (right), collected from the plankton. 19 July 2015. © Allison J. Gong
A metamorphosing sea urchin (left) and larval polychaete (right), collected from the plankton
19 July 2015
© Allison J. Gong

In the video clip below you can see the familiar baby-urchin-learning-how-to-walk, as well as a better view of the polychaete. Note the conspicuous segmentation and chaetae (bristles) that the animal splays out when disturbed or, in this case, gently squashed under a cover slip.

The little worm looks like it’s dancing! Sometimes you can see its four eyes.

Goodie #3:

Cyphonautes larva collected in plankton sample, 19 July 2015. © Allison J. Gong
Cyphonautes larva collected from the plankton
19 July 2015
© Allison J. Gong

This creature is called a cyphonautes larva. It is the sexually produced pelagic propagule of a benthic bryozoan colony, most likely Membranipora membranacea. If it looks like a swimming triangle, well, that’s exactly what it is.

Goodie #4:

This living lava lamp is very enigmatic. I called it a shmoo-type thing and was so intrigued that I isolated it into a separate dish for further observation. I was delighted to see that, a few minutes later, it had settled and metamorphosed into this:

It has eight stubby little tentacles and an obvious cnidarian appearance. I think it is a little anemone, but only time will tell.

Goodie #5:

Radiolarian collected from the plankton. 19 July 2015. © Allison J. Gong
Radiolarian collected from the plankton
19 July 2015
© Allison J. Gong

This beautiful object is a radiolarian, a type of marine amoeba. The main part of the cell is concentrated towards the center and pseudopodia are extended along the skeletal spines, which, in addition to making the cell an unpleasant mouthful, also aid in buoyancy. This one was rather large, measuring about 2 mm across. I saw many of these in today’s sample.

All in all I spent a very enjoyable morning collecting and looking at plankton. I didn’t see any coccolithophores, but I’m thinking that I probably should go out again with a finer-meshed net to see if I can catch them. And to see what will happen with the zooplankton if the phytoplankton remain scarce for the rest of the season.