Life in the sea

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?

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A star is born!

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?

Posted in Marine biology, Marine invertebrates | Tagged , , , | 1 Comment

I go on a treasure hunt

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, 19 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.

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The perfect storm

Although the last thing that any of us marine invertebrate biologists want to see again is a wasted sea star, the syndrome has once again been making its presence felt at the marine lab. It has been almost two years since I documented the initial outbreak, and while nobody is convinced that it has entirely run its course, most of us, myself included, had thought that perhaps the first wave had passed. Then, back in March of this year, I saw one of my stars doing this:

Bat star (Patiria miniata) showing severe symptoms of wasting syndrome, 16 March 2015. © Allison J. Gong

Bat star (Patiria miniata) showing severe symptoms of wasting syndrome, 16 March 2015.
© Allison J. Gong

Those large white blotches on the aboral surface are open wounds, or lesions, through which some of the animal’s innards are protruding. The arm towards the top of the photo has also begun dissolving, literally wasting away into the environment. The lesions eat right through the epidermis, liberating the skeletal ossicles that lie underneath it; I’ve circled two of them on the right side of the photo and there are two more at the bottom.

The discovery of this wasting animal was alarming and for a while I held my breath whenever I check on stars at the lab, but after several weeks of not seeing any additional sick animals I relaxed my guard and concluded the incident was a one-off. So imagine my horror to walk in this morning and see this in one of my tables:

Oral surface of a wasting bat star (Patiria miniata), 17 July 2015. © Allison J. Gong

Oral surface of a wasting bat star (Patiria miniata), 17 July 2015.
© Allison J. Gong

Sea stars generally don’t just lie on their aboral surfaces, and this animal was making no attempt to right itself. See how the margin between the arms is a little wavy? That isn’t normal, either, and shows that the animal’s ability to regulate its internal water content has been compromised. And while bat stars routinely scavenge by extruding their stomachs through the mouth and digesting whatever it comes into contact with, they don’t leave the stomach hanging outside the body when they aren’t feeding.

All of which gave me a bad feeling in the pit of my own stomach, which only got worse when I turned the animal over:

Bat star (Patiria miniata) with several small aboral lesions, 17 July 2015. © Allison J. Gong

Bat star (Patiria miniata) with several small aboral lesions, 17 July 2015.
© Allison J. Gong

The animal appears deflated and has small lesions all over its aboral surface. I was feeling a little deflated myself when I saw this. With stars it can be difficult to determine just how alive (or how dead) an individual is. This one didn’t fall to pieces when I picked it up, which didn’t exactly surprise me because Patiria is less prone to losing its arms via autotomy than the Pisaster species (ochre, short-spined, and jewel stars) and Pycnopodia helianthoides (sunflower star), in whom one of the symptoms of wasting syndrome is a violent ripping off of one’s own arms. I suppose this makes the whole episode marginally less horrific than when I saw my Pisaster stars wasting, or maybe I’ve become jaded.

In any case, I had to decide what to do with this sick star. It was in a table with half a dozen other bat stars, so whatever it was exposed to or was itself exuding has already been spread to the others. I couldn’t leave it there to rot in place, but neither did I want to throw it away if it was still somewhat alive. I turned the animal so it was oral-side-up again and left it alone to see what would happen. If it righted itself I’d assume it was more or less alive and isolate it in a quarantine tank; if it didn’t, then all hope was lost and it could be tossed. When I was ready to leave the lab several hours later, it was in the exact same position. Verdict: dead.

So, why now? I’ve been thinking about this, and here’s what I came up with. The densovirus that has been linked to sea star wasting syndrome is always around in the environment. Like other opportunistic pathogens it doesn’t usually cause a problem until a host organism becomes stressed or compromised. For the past two years we’ve been aware of wasting events up and down the coast, which wiped out the most vulnerable individuals. Animals with resistance, however, were able to survive. The survivors may have been weakened, though, and the mild El Niño of 2014 and the much stronger one we have now in 2015 have resulted in water temperatures much higher than normal. I haven’t plotted the data yet, but in June and July the water temperature has been hovering at 15-16°C, with jumps this week up to 18.5°C over the past couple of days. These warmer temperatures can be very stressful to animals, which may be just what the densovirus needed to “announce [its] presence with authority” (that’s a quote from my favorite baseball movie, Bull Durham). Outbreaks of wasting syndrome are probably caused by a combination of factors: population density of the host animal, presence of the densovirus, overall health of the host, water temperature, water chemistry, and others I haven’t thought of. We are certainly not close to a complete understanding of this phenomenon.

At this point I don’t have many stars left in my collection. I hope I get to keep them.

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The dearth — it has begun

In the spring and early summer, beekeeping is really easy. The nectar is flowing and the bees are busy and happy because there’s plenty of food for everybody. The colonies build up quickly and, if a beekeeper isn’t diligent, throw swarms when the bees feel they are too crowded. There’s a certain amount of good-natured competition among beekeepers for swarms but around here there are enough to go around.

The hives at my house face directly east into a wild canyon, where they forage on blackberry, coffeeberry, and poison oak in addition to the gardens and ubiquitous eucalypts in the neighborhood. It’s a pretty prime location for the bees, as they wake up as soon as the sun rises over the lip of the canyon and are shaded from the afternoon sun. Someday I’d like to do a pollen analysis of our honey and determine exactly what the bees are feeding on; it would be very interesting to see how that changes through the season.

Green, Blue, and Purple hives facing into the canyon behind my house, 16 July 2015. © Allison J. Gong

Green, Blue, and Purple hives facing into the canyon behind my house, 16 July 2015.
© Allison J. Gong

All through the spring I spent time on the landing at the top of the stairs near the hives, writing in my nature journal or drawing. I’d sit with my back against the fence, notebook on my lap and binoculars at my side, and watch birds flying past at eye level. Because of the nectar flow the bees were mellow and pretty much ignored me, even when they were foraging in the coffeeberry bush a mere meter or so away from my head. Sometimes they even landed on me, treating me as just another surface on which to take a brief rest in their busy day.

Have you ever just sat next to a bush that’s buzzing with bees? It’s one of the more joyful and pleasant things about springtime, in my opinion, and I recommend it highly.

However, all good things must come to an end, and this holds for the nectar flow as much as for anything else. This year we had a very strong nectar flow early in the season, starting in late January and continuing until, well, some time before today. I had suspected that the spring bonanza would be short and intense, with flowers putting all of their energy into heavy nectar production early in the year while there was still some water in the ground, and it seems I was right.

When the nectar dries up, bees and beekeepers enter a time called the dearth. We beekeepers can detect the onset of the dearth in a couple of ways: (1) the hives get lighter as the bees begin to eat through their honey stores; and (2) the bees get irritable because they’re not finding much forage. While beekeepers in the springtime boast about being able to tend their hives naked, nobody would dare do so in the late summer or autumn. It turns out that right now our hives are sending us mixed signals. They are still putting up honey, at least some of them are, and they’re getting pissy.

This afternoon I went outside to my usual spot on the landing to draw for a bit. It was very pleasant there for about 20 minutes, then a single guard bee decided that This Must Not Be. I’ve noticed that bees don’t seem to like dark hair, of which I have quite a lot, possibly because it makes them think “Bear!” It doesn’t matter whether my air is pinned up or flying loose, the bees find it, get tangled in it, and try to sting my head. That’s no fun for any of us. Anyway, this persistent guard bee got it into her tiny brain that I was not to be tolerated, and she kept buzzing around my head. The buzz of an angry bee sounds different from the gentle hum of a happy bee and I was alarmed immediately. She made her point and I fell in line. I packed up my supplies and left, but the diligent guard bee followed me all the way back to the house. At that point she decided that she’d done her duty and let me escape.

This defensive behavior will only get worse as we move into autumn. Even if the bees have enough honey stored to last through the winter, they will react to the shortening days of late July and August by refusing to continue feeding their drone brothers and more aggressively defending their hives. There will be no more lounging on the landing for me until next spring.

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