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During what has become my daily check to see what's going on in Younger Lagoon, I got totally lucky and was able to see and photograph lots of birds. A morning with mostly cloudy skies meant good light for picture-taking. So I took lots of pictures! Some of these are series and need to be viewed in order to see the action. Sure, I could have just shot videos, but where's the fun in that? Sometimes still photos show a lot more than video.

It was a great day to watch wading birds! Legs and beaks come in varying lengths, and a particular species' combination of beak length and leg length determine where and how the bird forages.

Long-billed curlews, snowy egret, and marbled godwit on the beach at Younger Lagoon
Shorebirds at Younger Lagoon. Left to right: Two Long-billed curlews (Numenius americanus); snowy egret (Egretta thula); long-billed curlew; marbled godwit (Limosa fedoa)
2021-01-30
© Allison J. Gong

While the long-billed curlew (N. americanus) has the longest beak-length-to-head ratio of any bird, the marbled godwit and whimbrel also have impressively long bills. In the photo below, the three birds with slightly downcurved beaks are whimbrels (Numenius phaeopus) and the one bird with the two-toned straight beak is the godwit (Limosa fedoa). Most of the godwits I've seen have beaks that are a smidge upturned, but this one looks pretty straight to me.

Whimbrels and marbled godwits in the surf zone at Younger Lagoon
Shorebirds at Younger Lagoon. Three whimbrels (Numenius phaeopus) with downcurved beaks and one marbled godwit (Limosa fedoa) with straight beak
2021-01-30
© Allison J. Gong

All of these birds forage by probing the sand with their beaks. All sorts of infaunal invertebrates are taken, and the mole crab Emerita analoga is a favored prey item. Obviously a longer beak allows for deeper probing in the sand, and the variation in beak lengths among the shorebird species may allow for niche partitioning. In other words, a long-billed curlew can reach down for prey items that are unavailable for birds with shorter beaks. The flip side of this equation is that birds with the "short" beaks might be better at picking up prey buried that are buried at shallow depths.

Prey are also distributed patchily along the beach itself, from the surf zone to the dunes, and these birds forage in the entire range. The length of the legs determines how far down into the surf zone they can go. When the beach is steep, as it is now at Younger Lagoon, the birds don't have much time to dig around in the surf zone before the next wave comes up. Click through the slide show to see this group of godwits, curlews, whimbrels, and a snowy egret react to an oncoming wave. It's important to note that while these birds do have some waterproofing in their feathers, they do not swim. Nor can they take flight if their feet aren't on the ground. Getting swept up by a wave and carried off the beach would likely be deadly for them.

The long-billed curlew is a favorite of mine, because I can't imagine what it would be like to go through life with a 2-meter beak sticking out of my face. They are fun to watch, and can probe remarkably fast with that long beak. This is one of the phenomena that is best shown by video.

You can watch how the birds forage within the surf zone, as in the slide show above, and also how long-billed curlews probe the sand higher up the beach.

Shorebirds foraging at Younger Lagoon
2021-01-30
© Allison J. Gong

These long-legged wading birds also feed in protected bodies of water and estuaries. All of these species can be seen at Elkhorn Slough as well as on the open coast, as one would expect from the Slough's position along the Pacific Flyway. Some birds migrate to California from far away. Marbled godwits, for example, spend the summer breeding season in the interior regions of North America, and winter along the Pacific, Gulf of Mexico, and Atlantic coasts. The long-billed curlew also breeds in the interior of the continent. Snowy egrets, on the other hand, are year-round residents.

I am grateful to have access to places like Younger Lagoon, where I can spend time outdoors without other people around, remove my mask, and take pictures of birds. I love that the Younger Lagoon Reserve has so many different habitats to explore, from ocean to beach to dunes to coastal scrub, in a small area. Fingers crossed that sooner rather than later, we'll be able to once again bring students there to study the natural world in the Reserve's outdoor classrooms.

In terms of weather, this has been the first real week of winter we've had so far this season. But finally we're getting some action from an atmospheric river, and it is bringing both much-needed rain and the threat of mudslides in mountain regions that were badly burnt just a few months ago.

Graphic showing what atmospheric rivers are and how they affect precipitation

During an El Niño event, the probability of higher-than-average rainfall in California is usually due to what are called Pineapple Express storms. These warm, wet storms occur when the atmospheric river is to the south and picks up and transports water from the tropics. La Niña, which is the counterpart to El Niño, typically results in drier-than-average conditions in California, but when the atmospheric river does come into play it comes from the north and is cold.

We are currently at the mercy of La Niña, and weather forecasters predict these conditions will continue through February and then begin to wane through the early spring. This means that the storms we've had over the past several days have been cold. According to our weather station, on Monday 18 January the high temperature was 24ºC (75ºF), and a week later on Monday 25 January the high was 12ºC (53ºF). It has continued to be chilly throughout the week. Today, Friday 29 January, we're getting a break between storm systems and it's beautifully sunny. Because of the sun it feels warmer, but the actual air temperature probably won't get much higher than it has been already this week.

Yesterday we were hit by what was probably the strongest of the storms in this particular atmospheric river. At the marine lab the waves were routinely splashing up and over the cliffs. When that much water crashes into solid land, the pounding is felt as much as it is heard. After doing my chores I wandered over to Younger Lagoon to see what was going on. I wanted to see if the lagoon had broken through the sand bar.

I spent some time watching the ocean, and this is what I saw:

Storm waves at Younger Lagoon
2021-01-28

That sand bar forms as sand accumulates on the beach during the summer, following the typical sand cycle along the California coast. Younger Lagoon does not drain a river, so there is not a constant flow of fresh water down to the ocean. There is some run-off from the surrounding agriculture fields, but the vast majority of water flowing through the lagoon is run-off from rain. It's that heavy flow of fresh water that sometimes breaches the sand bar and allows water from the ocean to mix with water in the lagoon.

Given how much rain we'd had, I thought it likely that the lagoon would have breached. But as you can see from the video above, it had not. Clearly, there hasn't yet been enough fresh water flow through the lagoon to break through the sandbar.

So we're still waiting for that event. I suspect that once it does, we'll know because of the smell.

In the meantime, the ocean continued to pound the coast. I was wearing my foul weather gear so I went to Natural Bridges to watch the waves slam against the rock formations. That was a fun excursion! The big swells were coming in so fast that the deep BOOM-BOOM-BOOM was almost continuous. Close to shore the water was a constant froth of movement.

Storm waves at Natural Bridges
2021-01-28

You can see how high the waves were hitting against the cliff. The mist blew quite far across the parking lot, and I went home with saltwater drying in my hair. Fortunately I got to spend the rest of the day indoors, drinking tea and keeping dry. Winter storms are great fun, as long as you don't have to be out in them!

According to my notes at the lab, the last time I spawned urchins was December of 2016, making it four years ago. It has always been something I enjoyed doing, but I didn't have a reason to until now.

When the coronavirus pandemic began almost a year ago now, access to all facilities at the marine lab was restricted to a group of people deemed essential. In my case, "essential" had to do with the fact that I keep animals alive. There were many hoops to jump through and inane questions to answer—for example, "What will happen if you don't go in to check on water and food?" and "How many animals will die if you do not have access to the lab, and how much effort [i.e., $$$] would it take to replace them?"—but in the end someone higher up in the food chain exercised some common sense and decided to let me have continuous access to the lab. So I've been at the lab pretty much every day, to check on things and make sure that air and water are flowing.

So over the summer we were running sort of bare-bones operations at the lab. There were many fewer people looking after everyday things. The autoclave broke and wasn't fixed until September. One of the casualties of this less-than-normal vigilance was one of the cultures in the phytoplankton lab. Our Rhodomonas flasks had been contaminated since late 2019, and we were struggling to rescue them. I tried so hard to keep them going ahead of the contamination, but ultimately failed. As of this writing all of the old Rhodomonas cultures have died.

In October, after the autoclave had been repaired, I decided to take action and replace our inevitably doomed Rhodomonas cultures. I found a company that sells small aliquots of many marine microalgae and ordered a strain of Rhodomonas that was isolated in Pacific Grove. May as well see if a local strain of algae works as a food for local larvae, right? The new Rhodomonas cultures seem to be growing well and it's time to see of urchin larvae will eat and thrive on it.

Equipment and glassware used to spawn sea urchins

About a month ago I collected 10 urchins to spawn. Yesterday was their lucky day! Purple sea urchins (Strongylocentrotus purpuratus) are broadcast spawners, and spawning is both inducible and synchronous. We can take advantage of the inducibility to make them spawn when we want, as long as they have ripe gonads. The difficulty is that we can't tell by looking whether or not an urchin is gravid, so all we can do is try to induce them and then hope for the best.

As I've written before, we induce spawning in sea urchins by injecting them with a solution of potassium chloride (KCl). KCl is a salt solution that causes an urchin's gonopores to open and release gametes if the gonads are ripe. I shot up 10 urchins yesterday, and eight of them spawned. An 80% spawning rate isn't bad, but only two of the eight were female and neither of them had a lot of eggs to give.

Since the gonopores are located on the aboral (top) of the urchin, the easiest way to collect eggs is to invert the animal on a beaker of seawater, like so:

Female sea urchin (Strongylocentrotus purpuratus) spawning
2021-01-12
© Allison J. Gong

In nature the eggs, which are a pale orange color, would be whisked away by currents to be (hopefully) fertilized in the water column. In the lab we can collect the eggs in the beaker, as follows:

This is much less damaging to the animal than trying to pipet eggs off the top of the urchin.

We try to collect sperm and keep it dry, so there is no putting males upside-down on beakers of water. Instead we pipet up the sperm and keep it dry in dishes on ice. When it's time to fertilize the eggs we dilute the sperm with filtered seawater and add a small amount to the eggs.

One of my favorite things ever is watching fertilization take place in real time, under the microscope. It truly is one of nature's most amazing phenomena. It is a great thrill to watch the creation of new beings.

In the video you see eggs being bombarded with sperm, probably at much higher concentrations than they would encounter in the wild. It is common knowledge that it takes only one sperm to fertilize an egg, but what would happen if two sperm penetrated an egg at the same time? I've written about polyspermy and the fast and slow blocks thereto, in case you'd like to refresh your memory about what is happening in the video.

A successfully fertilized egg is easily recognized by its fertilization envelope, which is the slow block to polyspermy.

Zygotes of the purple sea urchin (Strongylocentrotus purpuratus)
2021-01-12
© Allison J. Gong

After fertilization, the next step to watch for is the first cleavage division, which occurs about two hours later.

2-cell embryos of the purple sea urchin (Strongylocentrotus purpuratus)
2021-01-12
© Allison J. Gong

Aren't they pretty?

Over the next day or so the cleavage divisions continue, resulting in the stage that hatches out of the fertilization envelope. This stage is a blastula, which is a hollow ball of ciliated cells. The hollow space inside is called the blastocoel, and it is here that the larval gut will soon develop.

Blastula of the purple sea urchin (Strongylocentrotus purpuratus)
2021-01-12
© Allison J. Gong

It's easier to see the 3-dimensional structure of the blastula by watching it spin around.

As the blastula rotates under the coverslip, you can see the ciliary currents that would propel it through the water. You also see some objects that look like sperm and are, in fact, dead sperm, getting caught up in the currents.

The blastula is the same size as the egg. The embryo can't begin to grow until it eats, which won't happen until it has a gut. Over the next few days an invagination will begin at a certain location on the blastula which is called the blastopore; this invagination will eventually form the first larval gut. At that point I will have to start feeding them and calling them larvae.

And just to remind you of our humble beginnings, we begin life in much the same way as sea urchins. That blastopore, or initial opening to the larval gut, is the anus. The mouth doesn't exist until the invagination breaks through to the opposite end of the embryo. So yes, like the sea urchin, you had an anus before you had a mouth!

4

On the penultimate day of 2020 I met up with my goddaughter, Katherine, and her family up at Pigeon Point to have two adventures. The first one was to find a marble that had been hidden a part of a game. We got skunked on that one, although the marble was found after we left and the hider had sent an additional clue. The second adventure was an excursion to the tidepools. I've had a lackadaisical attitude towards the afternoon low tides this winter, not feeling enthusiastic about heading out with all of the people and the wind and having to fight darkness. But the invitation to join the marble hunt, on a day with a decent low tide, meant that I could spend a good deal of quality time with Katherine.

It is not unusual for a promising low tide to be cancelled out by a big swell. It happens, especially during winter's combination of afternoon lows and occasional storms. The swell yesterday was pretty big.

Here's the view to the north, from Pigeon Point:

Looking north from Pigeon Point
View to the north from Pigeon Point
2020-12-30
©Allison J. Gong

All that whitewash breaking over the rocks is not good for tidepooling, especially with small kids in tow.

This is how things looked to the south of the point:

View to the south from Pigeon Point
2020-12-30
©Allison J. Gong

This is Whaler's Cove, a sandy beach that lies on the leeward side of the point itself. See how the water is much calmer? It's amazing how different the two sides of the point are, in terms of hydrography, wind, and biota. The south side is much easier to get to, especially for newbies or people who are less steady on their feet. Being sheltered from the brunt of the prevailing southbound current means that the biological diversity is, shall we say, a bit subdued when compared to what we see on the north side of the point.

I first took Katherine tidepooling when her sister, Lizzie, was an infant riding in her mom's backpack. Katherine was about four at the time. Her mom and I were suprised at how much she remembered. She recognized the anemones right away, even the closed up cloning anemones (Anthopleura elegantissima) on the high rocks. She remembered to avoid stepping on them—that's my girl!

She wasn't all that keen on touching the anemones, though, even after we told her it feels like touching tape.

Giant green anemone in tidepool
Giant green anemone (Anthopleura xanthogrammica)
2020-12-30
©Allison J. Gong

She did like the sea stars, too. Purple is my favorite color and I think hers, too, so the purple and orange ochre stars were a hit. It was nice to see two large healthy ones.

I had some actual collecting to do, so it was a work trip for me. Late December is not the best time to collect algae, but I wanted to bring some edible seaweeds back to the lab to feed animals. We haven't had any kelp brought in since the late summer, and urchins are very hungry. They will eat intertidal seaweeds, though, and when I go out to the tidepools I bring back what I can. It will be a couple of months until we see the algae growing towards their summer lushness, but even a few handfuls of sea lettuce will be welcome to hungry mouths.

Bright green sea lettuce growing with red algae
Sea lettuce (Ulva sp.)
2020-12-30
©Allison J. Gong

Katherine and I walked up the beach for a little way to study one of the several large-ish crab corpses on the sand. This one was a molt rather than an actual corpse.

Rock crab molt on sand
Rock crab (Romaleon antennarium) molt
2020-12-30
©Allison J. Gong

Katherine found the missing leg a little way off, and we discussed why we call these limbs legs instead of arms. "They use their claws to pinch things, like hands," she said. Not wanting to get into a discussion of serial homology and crustacean evolution with a 6-year-old, I told her that calling the claws "hands" isn't a bad idea, since they are used a lot like the way we use our hands. But, I continued, the crab walks on its other limbs like we walk with our legs, so can we call those legs? She was happy to agree with that. I can tell I will have to be careful about how I explain things to her, so that she doesn't come up with some wonky ideas about how evolution works.

In the meantime, Lizzie, the little sister, was having a grand old time. She flooded her little boots without a complaint and, after her mom emptied the water from them, squelched happily along with soggy socks. That girl may very well grow up to be a marine biologist!

Once the sun went behind the cliff it started getting cold. With one child already wet we decided to head back. On our way up the beach we saw this thing, which I pointed out to Katherine:

"What is it?" she asked. When I asked what she thought it was she cocked her head to one said and said, "It looks like a rock." Then I told her to touch it, which she didn't want to do. So I picked it up and turned it over, to show her the underside:

Gumboot chiton (Cryptochiton stelleri)
2020-12-30
©Allison J. Gong

These big gumboot chitons do look more interesting from this side, because you can at least see that they are probably some kind of animal. Katherine had seen some smaller chitons on the rocks, so she had some idea of what a chiton is, but these are so big that they don't look anything like the ones we showed her earlier. Plus, with their shell plates being covered with a tough piece of skin and invisible, there are no outward signs that this bizarre thing is indeed a chiton. Katherine was not impressed.

At this time of year, when the sun decides to go down it goes down fast. But as we were walking back across the rocks the tide was at its lowest, so there was more terrain to explore. Then it was back up the stairs to the cars, where we could get warm and dry.

Beach and lighthouse at Pigeon Point

Oh, and Katherine and her mom and sister were able to find the hidden marble! They also hid one of their own for someone else to find.

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