Author: Allison J. Gong

Seasonality

Posted on by Allison J. Gong

People who moved here from other states often say that California doesn’t really have seasons. I think what they mean is that in general we don’t oscillate between frigid winters and hot, humid summers. The Pacific Ocean moderates weather conditions through most of the state, giving us our Mediterranean climate characterized by a short rainy season and a long dry summer. However, California is a very large state with many different climate zones. Here on the coast our summers are cool and foggy, while in the interior of the state summers can be quite hot, upwards of 38° C for weeks at a time. Snow falls in the Sierra Nevada, providing much of the state’s annual water budget, but the rest of the state usually remains snow-free for most of the winter.

That said, California does of course have seasons, even though they may not be as in-your-face as what you’d see in, say, New England. One of the ways to experience the seasons is to observe the comings and goings of migratory wildlife, especially birds. In fact, bird migration patterns make up a significant part of phenology, the study of the timing of biological events in the natural world. California’s position along the Pacific Flyway provides fantastic bird watching opportunities throughout the year. There are many locations within California that are pit stops for birds migrating up and down the coast and overwintering oases for birds that breed much farther north.

The San Luis National Wildlife Refuge (NWR) in Merced County is one such place. Located in the Central Valley, it represents some of the original habitat in this part of the state. The San Joaquin River winds through the Reserve, providing riparian habitat, although the river is currently a mere ghost of its former glory. Since 2009, federal and state entities have worked to restore the San Joaquin, increasing water flows and cleaning up the surrounding lands. While it would be marvelous to see chinook salmon once again migrating from San Francisco Bay up the San Joaquin, it hasn’t happened yet. The re-establishment of salmon runs up to just below Friant Dam would indicate a healthy San Joaquin River, and I really hope to see it in my lifetime.

Before the era of modern agriculture, much of the Central Valley flooded with the winter rains and spring snowmelt. Only a tiny fraction of these wetlands remain; most have been drained for agriculture and further deprived of water by state and federal water diversion projects. In areas such as these, small pools form during the wet season. These vernal pools–so called because they are often at their deepest during the spring–are ephemeral habitats. They almost always disappear during the long dry summer, but during their short existence they provide living space for a unique biota. A few vernal pools occur in most of the flat areas of California, although there are far fewer of them than before, and they differ biologically throughout the state. It is not uncommon for each vernal pool in a given area to have its own combination of flora and fauna, all of which have adapted to thrive in both desiccated and flooded conditions.

System of vernal pools at San Luis National Wildlife Refuge
2018-12-26
© Allison J. Gong

On our way back to the coast after spending Christmas with my family, we stopped at the San Luis NWR to do some wildlife watching. The visitor center was closed because of the federal government shutdown, but the roads were open. The Refuge has two auto tour routes, one to the tule elk reserve and the other to see resident and visiting aquatic birds. We chose to drive the bird route, because winter is a good time to see birds that spend the rest of the year at much higher latitudes.

2018-12-26
© Allison J. Gong

Coots (Fulica americana) are ubiquitous in California’s wetland habitats, and because of that they are easily overlooked. When I was little we called them ‘mudhens’ and smirked at them because they weren’t ducks. Of course I now realize that that thinking is entirely unfair, and have come to appreciate coots because they aren’t ducks.

Coots (Fulica americana) at San Luis National Wildlife Refuge
2018-12-26
© Allison J. Gong

In addition to the coots, which weren’t much of a surprise because we expected to see them, we saw large numbers of several species that we weren’t as familiar with. There were ducks and geese, which took us some time to ID because they weren’t mallards and Canada geese. Fortunately I keep a bird field guide and binoculars in the car! My favorite bird ID book is the National Geographic Field Guide to the Birds of North America; we keep one of the later editions at home, but my beloved and well battered third edition lives in the glove compartment.

The ducks turned out to be northern shovelers, which I’ve seen at Elkhorn Slough. True to the typical avian way of doing things, the males are strikingly colored, with brilliant green heads, while the females are a dark streaky brown. In the photo below, a female swims with two males.

Northern shovelers (Anas clypeata) at San Luis National Wildlife Refuge
2018-12-26
© Allison J. Gong

The geese were entirely new to us. We first saw them flying overhead in the V-shaped formations that you expect from a gaggle of geese in the air. But they didn’t honk like Canada geese so we knew right away that they were something different.

Geese in flight
2018-12-26
© Allison J. Gong

I wasn’t able to ID these until we got home and I looked at my photos on the computer. iNaturalist helpfully gave me a tentative ID of greater white-fronted goose (Anser albifrons), which I was happy to go along with.

Greater white-fronted geese (Anser albifrons) at San Luis National Wildlife Refuge
2018-12-26
© Allison J. Gong

In North America, greater white-fronted geese nest in the Arctic of western Canada and through most of Alaska, including out along the Aleutians. They migrate south to spend the winter along the Gulf coast and along the eastern coast of the Sea of Cortez. The winter wetlands of the Sacramento and San Joaquin Valleys host many of these geese, and smaller numbers overwinter in coastal Oregon and Washington.

Living in California, I don’t usually expect to encounter any species whose common name includes the word ‘tundra’, but tundra swans do indeed spend their winters here! They nest in the very high Arctic on tundra, a habitat that is threatened by climate change, and winter is the only time we would see them in the lower 48, when large flocks venture south to overwinter near lakes and estuaries. I’ll keep an eye out for them next time I’m at Elkhorn Slough or Moss Landing.

Tundra swans (Cygnus columbianus) at San Luis National Wildlife Refuge
2018-12-26
© Allison J. Gong

We saw hundreds of these swans hanging out with the shovelers. Only a few were within photograph range, as I don’t have a very long telephoto lens (yet!), but there were lots of large white blobs floating, foraging, preening, and sleeping. They were fun to watch through the binoculars. We had hoped to see some sandhill cranes in the Refuge, too. We had seen them off in the distance, much too far to be photographed, but it wasn’t until we were on the last leg of the auto tour that we saw them up close. They were not mingling with the swans and geese, and as far as we could tell tended to gather in single-species flocks. They seemed to be more skittish, too, and would startle and fly away when they heard human noises. I had to move slowly and quietly to get this close to them. Even the sound of the camera shutter caught their attention and made them wary.

Sandhill cranes (Antigone canadensis) at San Luis National Wildlife Refuge
2018-12-26
© Allison J. Gong

The Central Valley is Ground Zero for sandhill cranes in California, where they can be seen only in the winter. They don’t breed here, of course, but there is a small population of ~460 pairs of sandhill cranes breeding in far northeastern California. There are locations in the Central Valley that are known for hosting large crane populations in the winter, and one of my goals is to witness a big ‘fly-in’ event, when huge flocks come in to roost in the evening. I’ve seen pictures, and it looks like a spectacular sight. I want to see it with my own eyes.

All this is to say that we do indeed have seasons in California. The shifts between summer and winter are perhaps more subtle here than in other states, but an observant eye keeps track of changes in the natural world. And you don’t have to be a trained scientist to track seasonal changes wherever you live, either. We tend to use temperature to tell us which season we’re in, but in reality light is a much more reliable indicator. Just think of how dramatically temperature can fluctuate in a few days, and how much more extreme these fluctuations seem to be in recent years, due to climate change. Day length cycles, however, remain constant over geologic time, as we humans haven’t yet figured out a way to mess with the tilt of the earth’s axis. Everyone notices how the amount and quality of light change with the seasons. It takes just a little more effort to notice the ways that life responds to those changes.


I return to the field

Posted on by Allison J. Gong

For a number of reasons–a lingering injury to my bum knee, scheduling difficulties, and ongoing postconcussion syndrome–I missed the autumn return of the minus tides. At this time of year the lowest tides are in the afternoon, and at the end of the day I just didn’t have the energy to deal with field work. It took until today, the winter solstice, for me to find my way back to the intertidal. An additional motivating factor was a request from both the Seymour Center and Seacliff State Beach for critters to populate their displays. So off I went!

Davenport Landing beach
Davenport Landing Beach
21 December 2018
© Allison J. Gong

Over the past day or so a storm system blew through the area. It didn’t drop any rain on us in Santa Cruz, but earlier this week the National Weather service issued a small craft advisory and suggested that people stay off the beach, due to a combination of big swell and high tides. Usually when I go collecting at Davenport I go to the reef on the north end of the beach, which has more varied vertical topography and a similar, but generally richer, biota than the gently sloping benches to the south. However, the big swell had washed away a lot of the sand, leaving the beach steeper than it would be in the summer, and even the -1.0 ft tide didn’t make the reef safely available to someone not clad in a wet suit.

So I trudged across the beach and went to the south instead. It gave me an excuse to poke at the stuff that had been washed up onto the beach and look for nice pieces of algae to take to the Seymour Center. Algal pickings are rather slim in the winter, but I did find several decent small clumps that will do nicely in the touch table. One noteworthy find was a dead gumboot chiton (Cryptochiton stelleri). There were four such corpses washed up on the beach, in varying states of decay and stench.

Cryptochiton stelleri
Dead gumboot chiton (Cryptochiton stelleri)
21 December 2018
© Allison J. Gong

Cryptochiton stelleri is the largest of the chitons, routinely growing to length of 20 cm. It’s a hefty beast, too. The chitons as a group have their greatest diversity in the intertidal, but Cryptochiton is a subtidal creature. Unlike the intertidal residents, Cryptochiton‘s sticking power is pretty weak. Living below the worst of the pounding of the waves, it generally doesn’t have to cling tightly to rocks. However, because it doesn’t stick very well, Cryptochiton often gets dislodged by strong surge, especially during spring tides. Then they get tumbled by the waves and wash up dead on the beach. I don’t think I’ve ever seen a live Cryptochiton washed up.

The reef to the south of the beach consists of flat benches that slope down to the ocean. There are some channels and a few pools, but otherwise there is no real topography. Of course, for creatures living in the intertidal, there is topography–the nooks and crannies, as well as vertical faces, provide a variety of microhabitats.

Intertidal benches on the south end of Davenport Landing
21 December 2018
© Allison J. Gong

Mopalia lignosa is one of the intertidal chitons that I’m always delighted to find because it’s not as common as some of the others, and it’s a beautiful animal. The species epithet lignosa means ‘wood’ and refers to the patterning on the dorsal shell plates.

Mopalia lignosa
21 December 2018
© Allison J. Gong

As usual, there were spectacular anemones to be seen. And I saw something new! Anthopleura sola, the sunburst anemone, is one of the large aclonal anemones that is very common. At Natural Bridges there is a brilliant fluorescent A. sola in a pool on one of the benches I visit. I’ve been keeping an eye on this animal for a couple of years now, just to reassure myself that it’s still there and doing well. The animal is hardly hidden, but it feels like a little insiders’ secret that not everybody knows about.

For the first time, I saw fluorescent A. sola at Davenport Landing. Three of them, in fact! And boy, were they all bright!

Fluorescent Anthopleura sola anemone
21 December 2018
© Allison J. Gong
Another fluorescent Anthopleura sola anemone
21 February 2018
© Allison J. Gong

The third fluorescent anemone was closed up. There were just enough partial tentacles visible to see that it is indeed a fluorescent specimen.

A third fluorescent Anthopleura sola anemone
21 December 2018
© Allison J. Gong

Now, I don’t spend as much time at the south end of the beach as I do on the north side, but until today I had never noticed these fluorescent animals. Could I have missed them all this time? It’s kind of hard to miss a neon green animal the size of a cereal bowl! At any rate, now that I know they exist and hopefully remember where they are, I’ll be able to keep an eye on them, too.

Webbed feet, but not a duck!

Posted on by Allison J. Gong

A few years ago I had a student, Brett, who had played baseball while he was in high school. One day in lab the students and I were chatting about nothing in particular when the conversation turned to the difficulty of memorizing the scientific names of all the animals they were studying. We got into one of those debates about the usefulness of common names as opposed to scientific names, and I got on my soapbox to deliver my usual sermon: common names are fine, if you are talking with non-scientists and as long as the names are unambiguous, but for scientific communication and to avoid confusion and ambiguity you need to use an organism’s scientific name. Also, taxa that have been well studied for decades or centuries, such as birds and flowers, often have common names that are widely accepted and used by both scientists and naturalists. This evolved into a discussion of bird-watching and how birders have developed a sort of shorthand for birds’ common names; RTHA for red-tailed hawk (Buteo jamaicensis), for example.

At this point Brett chimed in with a bit of wisdom imparted by one of his high school baseball coaches, who said, “All you need to know to identify birds is whether or not it has webbed feet. If it has webbed feet, it’s a duck! And if it doesn’t have webbed feet, it’s a pigeon!” I must say, as far as methods for distinguishing different groups of birds, I have heard worse. The possession of webbed feet at least has a functional significance, and it’s usually easy enough to see a bird’s feet, or at least to infer the presence or absence of webbing by observing the bird in its habitat.

A variety of web-footed birds at Natural Bridges State Beach
29 October 2018
© Allison J. Gong

My own proficiency at IDing birds is sketchy at best. I’m pretty good with the birds that I see all the time in my backyard and canyon, and I can get most other sightings down to major group, but there are some types that I will probably always find difficult. Gulls and the wading shorebirds, for example. Gulls are notoriously problematic because there are many species and they go through three or four juvenile stages before attaining adult plumage. Wading shorebirds (sanderlings, and whatnot) all look alike to me, and absolute size differences are hard to discern when dozens or hundreds of birds running up and down the beach are about the same size.

One bird that I can easily identify based on its silhouette, is a cormorant. They are related to pelicans and have the same gular pouch under the throat that they use to catch fish, but are their bodies are much more streamlined. Unlike pelicans, which dive from the air to catch fish, cormorants are pursuit divers, using their webbed feet to swim after fish below the surface. These webbed feet are located at the posterior end of the body, where they are well positioned for propulsion under water (think about where a submarine’s propeller is located). Having their feet at the back end of the body gives cormorants a more upright stance on land compared to pelicans, whose feet are positioned towards the middle of the body and thus carry themselves along a more horizontal axis.

Pelicans and cormorants at Natural Bridges State Beach. Note differences in posture and position of the feet.
29 October 2018
© Allison J. Gong

Clearly, despite their webbed feet, cormorants are not ducks. However, like ducks they do spend most of their time on or in the water. Cormorants are unusual for aquatic birds in that they don’t have oil in their feathers. You’ve heard the phrase “Like water off a duck’s back”, right? It means not being affected by external events, instead letting them roll off and away the way that water beads and falls off a duck’s plumage. The saying is true because ducks and other waterfowl do indeed have a coat of oil in their feathers. In fact, most birds have feathers that are water-repellent to some degree. The oil keeps water from penetrating through the feathers and chilling the body. It also provides additional buoyancy. When you see a bird preening, part of what it is doing is distributing the oils over the feathers in an even coat.

Double-breasted cormorant (Phalacrocorax auritus) drying its wings at Antonelli Pond
29 October 2018
© Allison J. Gong

Not having oiled feathers, cormorants soon become waterlogged, which enables them to stay underwater and swim efficiently below the surface. Unfortunately, getting soaked to the skin means the cormorants are susceptible to hypothermia. When they have finished feeding, they need prepare their feathers before they can make any prolonged flights. You will often see cormorants perched on rocks or cliff ledges, basking with their backs to the sun and  wings outstretched. They have to do this to dry their wings and warm up their bodies before they can fly. Their dark  coloration absorbs heat quickly and speeds up the drying process.

Even though they don’t have oiled feathers, cormorants do spend a lot of time preening. They use their beak to smooth feathers and make sure they lie properly on the body. Usually they pay special attention to the wing feathers, as the proper condition and alignment of these feathers makes flight possible.

Double-breasted cormorant (Phalacrocorax auritus) preening at Antonelli Pond
29 October 2018
© Allison J. Gong
Double-breasted cormorant (Phalacrocorax auritus) preening at Antonelli Pond
29 October 2018
© Allison J. Gong

Another characteristic that makes cormorants different from ducks is their solid bones. Almost all of the flying birds have hollow bones, to lighten the load they have to carry through the air. Flight is a very energetically expensive endeavor, and over millennia the hollow skeleton has evolved to make it slightly less so. Penguins, of course, do not fly in air, but their swimming motion is essentially underwater flight. They have solid bones, to provide weight and counteract the positive buoyancy generated by their blubber and oiled feathers. Like their flightless tuxedo-wearing relatives, cormorants also have solid bones, to help keep them underwater as they pursue fish.

The hitch in this plan for cormorants, however, is that they do fly. Cormorants travel through the air and hunt for prey in cold water. They certainly aren’t the only birds with this combination of habits; there are tern species, for example, that migrate thousands of miles and feed by plunge diving. But cormorants, being pursuit divers, spend more time underwater than most other flying birds. They have had to evolve a combination of adaptations for flight (flight feathers, wings long enough to enable flying) and adaptations for swimming underwater (legs at the back of the body, lack of oil in feathers, and dense bones). Natural selection is often about just this sort of compromise. An organism doesn’t have to be perfect to be fit for its environment, but it does have to be good enough. And when an animal spends time in both air and water, it has to be good enough in two environments. Cormorants, traveling through air and hunting in water, manage to be successful at both and thus persist.

On fragile wings of steel

Posted on by Allison J. Gong

The other day I joined the Cabrillo College Natural History Club (NHC) on a natural journal walk through Natural Bridges State Park and Antonelli Pond here in Santa Cruz. The NHC is a student club at the college where I teach, and I attended one of their meetings early in the semester. It’s a very active club, and although I’m not currently one of the official faculty sponsors I hope to become one in the future. I had a prior commitment and couldn’t meet them when they started their walk, but since they were traveling at what club president described as “a nature journaling pace” I was able to catch up with them.

Monarch butterflies (Danaus plexippus) overwinter at Natural Bridges. On warm sunny days they flit about, feeding and warming their bodies in the sun. When it’s cold or raining they huddle together in long, drooping aggregations from the eucalyptus trees. It hasn’t been cold yet this year, but in November of 2017 I went out on a chilly morning and was able to photograph monarchs clustered together.

Monarch butterflies (Danaus plexippus) at Natural Bridges State Beach
18 November 2017
© Allison J. Gong
Monarch butterflies (Danaus plexippus) at Natural Bridges State Beach
18 November 2017
© Allison J. Gong

These two photographs are the same clump. Notice that the butterflies’ wings look very different when they are closed up. The insects roost with their wings held together over the back, showing the paler, dusty undersides. I think this posture minimizes risk of damage to the fragile wings as the butterflies huddle close together to retain as much warmth as possible. As the sun warms their bodies the butterflies begin opening and closing their wings to generate additional heat for their flight muscles. The brilliant orange color of the top side of the wings is the hallmark of a monarch butterfly.

The monarchs hanging out at Natural Bridges in 2018 are the great- great- grandchildren of the butterflies that were here last year. It takes four generations to complete one migration cycle. The butterflies in Santa Cruz today emerged from chrysalises up in the Pacific Northwest or on the west slope of the Rocky Mountains, and flew thousands of miles to get here. They’ll be here through the winter, departing in February to search for milkweed on the western slope of the Sierra Nevada. The eggs they lay there will hatch into caterpillars and eventually metamorphose into the butterflies of Generation 1 in March and April. Generation 1 butterflies migrate further north and east, lay eggs on milkweed, and die after a post-larval life of a few weeks. Generation 2 butterflies, emerging in May and June, continue the northeast migration, lay eggs on milkweed, and die. Their offspring, the Generation 3 butterflies, emerge in July and August and disperse throughout the Pacific Northwest and eastward to the Rockies; they lay eggs on milkweed and die. Generation 4 butterflies emerge in September and October, and almost immediately begin migrating south to where their great- great- grandparents overwintered the previous year. Of the four generations, 1-3 are short-lived, lasting only a few weeks before dying. Only Generation 4 butterflies live long, and their job is to escape the winter and survive elsewhere in a milder climate.

Monarch butterflies (Danaus plexippus) at Natural Bridges State Beach
18 November 2017
© Allison J. Gong

This truly is an extraordinary migration. Given that each individual travels only part of the migration route, how do they all know where they’re supposed to go? Each individual is heading for a location that hasn’t been encountered for four generations. Day length cycles are probably the primary migration trigger for each generation. I imagine that since each generation is born at a different latitude from the others and at different times of the year, day length signals may be generation-specific, at least enough so to tell the butterflies where they should go.

One of the students asked a great question: Other than the fact that they make the long leg of the migration and live longer, are there any differences between Generation 4 butterflies and the others? I don’t know the answer to that. I suspect that there may not be obvious morphological differences, but there certainly are physiological differences. The Generation 4 butterflies have much greater physical stamina than Generations 1-3, and have to fuel flight muscles to travel over 1000 miles. That’s quite a feat for an animal that looks so delicate! Appearances can be deceiving.


What is essential is invisible to the eye

Posted on by Allison J. Gong

When I teach sponge biology to students of invertebrate zoology, I spend a lot of time describing them as phenomenal filter feeders, and suspect that most other professors do the same. There really are no animals that come close to possessing sponges’ ability to remove very small particles from the water. Sponges have this ability despite the fact that their bodies are extraordinarily simple. I can draw pictures on the board to diagram the variety of sponge body types, but I’ve always wanted to show students how these bodies actually work.

Thing is, from the outside sponges just aren’t that interesting. Some grow into large, conspicuous tube or vase shapes, but most occur as crusts of varying thickness and color. For example:

Sponge in display tank at Seymour Marine Discovery Center
10 September 2018
© Allison J. Gong

or this:

Sponge in aquarium at Long Marine Lab
24 September 2018
© Allison J. Gong

Not much to write home about, is it?

But as with most things invertebrate, sponges are more complex than they appear to be at first glance. And of course their complexity can be best appreciated when you observe sponges under the microscope. That’s what I’ve been doing over the past few weeks: making wet mounts of living sponge and looking at them under the compound microscope. I’m still figuring out the best way to take photos through the scope, and trying to find the magic combination of lighting, magnification, and depth of field to obtain the clearest images.

Let’s take a step back and review some basic sponge fundamentals. Sponges are animals in the phylum Porifera. Their bodies are characterized by a lack of true tissues; in other words, a sponge’s body consists of various types of cells that do not form permanent connections. The different types of cells have different functions, but most of the cells retain the characteristic of totipotency, the ability to differentiate into another cell type as needed.

The sponge cells that do the filtering are called choanocytes. They form the lining of the sponge’s body cavity. Choanocytes consist of a cell body and a collar region of microvilli that form a ring. From the center of the ring protrudes a single flagellum, whose undulations travel from base to tip. The choanocytes are arranged so that the flagella face into the body cavity, and their collective beating draws water through the body. The flagella also capture food particles, which are phagocytosed by the cell.

Ascon body type of a sponge. Arrows indicate direction of water flow.
© Sinauer Associates, Inc.

In its simplest tubular form, a sponge can be visualized as a miniature vase, with a single body cavity called a spongocoel (‘sponge cavity’) which is lined with choanocytes. Water enters the sponge through many microscopic pores on the outer skin of the body, is filtered by the choanocytes, and exits through a single opening called the osculum. This system works, but the efficiency of filtering is limited by the surface area of the choanocyte layer lining the spongocoel, and very few sponges have this body type.

Now if you imagine making invaginations into the choanocyte layer and continue the choanocytes into the channels you create, you could increase the filtering surface area of a sponge without having to increase its overall body size. Continue this maneuver to its logical end and you’d end up with something that resembles a cluster of grapes. The skin of the grapes would represent the layer of choanocytes, all oriented so that their flagella face the hollow interior of the grape, which would correspond to what we call a choanocyte chamber. This type of body plan has a vastly expanded surface area to volume ratio compared to the tubular form, and these sponges achieve the largest sizes. Incidentally, natural selection has used this exact same strategy to maximize the respiratory exchange surface area of your lungs: gas exchange occurs in the alveoli, which are tiny thin-walled sacs where oxygen diffuses into and carbon dioxide diffuses out of capillaries. The total respiratory surface area of your lungs is about 70 m2—i.e., roughly equivalent to one side of a standard tennis court, without the doubles lanes—all tucked neatly into the volume of your thoracic cavity.

The canals leading into and out of each choanocyte chamber are smaller than the chamber itself, and this arrangement takes advantage of some fundamental fluid dynamics: a given volume of water flows faster through a tube with a narrow diameter and slower through a tube with a wider diameter. Water travels relatively fast through the narrow canals on either end of a choanocyte chamber and slows down significantly within the chamber proper. This gives the choanocytes time to capture all of the food particles in the water stream, and speeds the water to the outside of the body once it has been filtered.

Now we can get back to the animals themselves. Their external appearance may not look like much, but sponges are very interesting when viewed under a microscope. I’ve been taking samples and squashing them under coverslips for a close look.

Here’s a view under darkfield lighting:

Piece of a living sponge, viewed with darkfield lighting
8 September 2018
© Allison J. Gong

The clear-ish objects that look like the back roads of a map are spicules. They provide a bit of skeletal support for the sponge’s body and help to deter predators–who would want to bite a mouthful of glass splinters?

When I switched to higher magnification and phase-contrast lighting I could see hollow spherical structures that vaguely resembled blackberries. I felt a thrill of excitement to realize that these were probably choanocyte chambers, and I was looking at the choanocytes themselves!

Interior of sponge body
8 September 2018
© Allison J. Gong

Here’s another view at the same magnification, which shows more clearly the cells of the chamber:

Choanocyte chambers
8 September 2018
© Allison J. Gong

The chambers themselves closely resemble the blastula stage of early animal embryology. Like a blastula, a choanocyte chamber is a hollow ball of cells; unlike a blastula, which has a ciliated outer surface, a choanocyte chamber consists of flagellated cells with the flagella oriented towards the inner hollow space. At a bit less than 40 µm in diameter, the chambers are about half the size of my sea urchin blastulae.

Remember how I said that the structure of the choanocyte chambers is similar to that of our alveoli? You may not be able to visualize the alveoli in your lungs, but this photo shows how the chambers resemble a cluster of grapes.

Choanocyte chambers
22 October 2018
© Allison J. Gong

Because it’s impossible to see the three-dimensional structure of the chambers from the single plane of focus you get with a photograph, I shot some video while focusing up and down through the sample on the slide.

They really do look like grapes, don’t they?

Playing in the sand, for science

Posted on by Allison J. Gong

This semester I am teaching a lab for a General Biology course for non-majors. I polled my students on the first day of lab, and their academic plans are quite varied: several want to major in psychology (always a popular major), some want to go into business, a few said they hope to go into politics or public policy, and some haven’t yet selected a field of study. I think only one or two are even considering a STEM field. Which is all just to say that I have a group of students whose academic goals don’t have much in common except to study something other than science. Several of them are the first in their families to go to college, which is very exciting for them and for me.

Most of the activities we do in this class are lab studies. Last week, for example, the students extracted DNA from a strawberry (100% success rate for my class, thank you very much) and then used puzzles and 3-dimensional models to understand the structure of DNA. We do have a couple of field trips scheduled, though, which are the days that students really look forward to. Outside the classroom is where most of the fun stuff happens.

Today I took my class to the beach! We were there to do some monitoring for LiMPETS (Long term Monitoring Program and Experiential Training for Students). For the past few years I’ve taken my Ecology students out to the intertidal to do the rocky intertidal monitoring. The General Bio students don’t have the background needed for the intertidal monitoring and I don’t have the classroom time to train them, so we take them to do sand crab monitoring instead. This is a simpler activity for the students, although the clean-up on my end is a lot more intensive even though I get them to help me.

Dorsal view of Emerita analoga at Franklin Point
15 June 2018
© Allison J. Gong

Emerita analoga is a small anomuran crab, more closely related to hermit and porcelain crabs than to the more typical brachyuran crabs such as kelp and rock crabs. It lives in the swash zone on sandy beaches and migrates up and down the beach with the tide. Its ovoid body is perfectly shaped to burrow into the sand, which this crab does with much alacrity. The crabs use their big thoracic legs to push sand forward and burrow backwards into the sand until they are entirely covered. They feed on outgoing waves, sticking out their long second antennae (which can be almost as long as the entire body) and swivel them around to capture suspended particles.

Emerita analoga feeding in an aquarium

We went out to Seacliff State Beach to count, measure, and sex sand crabs. The protocol is to lay out a 50 m transect along the beach, roughly parallel to the shore where the sand remains wet but isn’t constantly covered by waves. Students draw random numbers to determine their position along the horizontal transect and venture out into the ocean, measuring the distance between the transect and the point where they are getting wet to the knees. Then they divide that distance by 9 to yield a total of 10 evenly spaced sampling points along a line running perpendicular to the transect.

Students collecting sand crabs at Seacliff State Beach
28 September 2018
© Allison J. Gong

The corer is a PVC tube with a handle. It is submerged into the sand to a specified depth and collects a plug of sand that is dumped into a mesh bag. Sand is rinsed out of the bag and the crabs remain behind. Students then have to measure and sex each of the crabs.

Rinsing the bag
28 September 2018
© Allison J. Gong
“What’s in the bag?”
28 September 2018
© Allison J. Gong

Each crab is classified as either a recruit (carapace length ≤9 mm) or a juvenile/adult (carapace length >9 mm). Students get to use calipers to measure carapace length, which they enjoy. Adult crabs are sexed, and females are examined for the presence of eggs.

Students measure a sand crab (Emerita analoga)
28 September 2018
© Allison J. Gong

A sand crab’s sex is determined by the presence or absence of pleopods, abdominal appendages that females use to hold onto eggs. If a female is gravid, the eggs are visible as either bright orange or dull tannish masses tucked underneath the telson (see below):

Ventral view of gravid female Emerita analoga
15 June 2018
© Allison J. Gong

The pointed structure in the photo above is the telson. You can see the tan eggs beneath the telson. They look like they would fall off, but they adhere together in a sticky mass until they are ready to be released. Adult females have pleopods whether or not they are gravid, making it easy to sex the crabs even when they are not reproductive.

Most of the larger crabs today were gravid females and could be sexed with a quick glance at the ventral surface. Sexing the smaller individuals requires a lot more effort. The crab’s telson has to be gently pulled back to expose the abdomen, which isn’t easy because the crab doesn’t like having its parts messed with. In fact, one of the ways to determine whether or not a crab playing dead is really dead is to pry up its telson–a dead crab will let you without making a fuss, while a live one will start thrashing about.

Students sexing a sand crab (Emerita analoga)
28 September 2018
© Allison J. Gong

It was a good day to spend time at the beach. The weather got better as we worked and the water wasn’t very cold. The students had a good time splashing around in the waves, and they all fell in love with the crabs. There were a few sad moments when crabs got chopped in half by the edge of the corer, but the vast majority were released back to the ocean unharmed. From a teaching perspective, I was happy to give the students an opportunity to do some outdoor learning. After all, the world is our biggest and best classroom. Most students learn best when they get to actually ‘do’ science, and even though most of this group will not go on to complete a science major, they hopefully have a better appreciation of what it is like to collect real data as citizen scientists.

Cleaning up

Posted on by Allison J. Gong

In the wee hours of Sunday 12 August 2018, the F/V Pacific Quest ran aground near Terrace Point. Over the next 24 hours she broke apart and began leaking diesel fuel into Monterey Bay. Fortunately most of the diesel was removed from the wreck, but the boat itself continued to disintegrate, with a lot of the debris washing up on the nearby shoreline. Due to the wreck’s position on the beach, clean-up crews have access to it only at low tide. We are now getting into a period of neap tides, limiting the time that people and equipment can be safely deployed on the beach. The good news is that after a delay yesterday due to an electrical problem, the removal of the Pacific Quest itself has begun.

The real deconstruction of the boat started during the evening low tide on 15 August.  It was supposed to start on the morning low tide, but there was a problem with the equipment and the crew spent the day waiting for and installing parts. The salvage crew used a crane to lower a small excavator onto the beach, which gathered debris into a large pile. The excavator was also used to smash the remains of the boat into smaller pieces, so the crane could hoist them up the cliff. My husband walked down to the lab and took some video of the action:

I was at the lab on the morning of 16 August and took some pictures, too. The coastal access pathway is blocked around the area where the salvagers are working, so I could get only so close. Plus, the lighting conditions were about as bad as daylight can be, for taking photos: I was shooting directly into a bright morning sun, with a lot of fog in the air. As a result these photos aren’t great, or even good, but they give a sense of what was going on at the time.

This picture of the crane was taken before any actual clean-up activity had started. The crane is positioned near the edge of the cliff on the coastal access trail. In this photo it is swiveled 180° away from the cliff.

Crane used to remove wreckage from the beach
16 August 2018
© Allison J. Gong

While the crane was being fired up and moved into working position, two guys were on the beach using an excavator on the beach remove debris from the deck of the F/V Pacific Quest into a pile on the beach itself:

Salvage crew clearing wreckage of the F/V Pacific Quest
16 August 2018
© Allison J. Gong

Then salvage workers attached a piece of debris to the line that was lowered by the crane:

Salvage crew clearing wreckage of the F/V Pacific Quest
16 August 2018
© Allison J. Gong

And the crane began to lift up the chunk of debris:

Salvage crew clearing wreckage of the F/V Pacific Quest
16 August 2018
© Allison J. Gong © Allison J. Gong

And finally the piece of wreckage was taken off the beach:

Crane removing debris of F/V Pacific Quest
16 August 2018
© Allison J. Gong

I imagine the same sequence of events was repeated many times that morning, as often as the tide would allow. I hope the salvage guys are also picking up the flotsam that was carried to other beaches. The work will be limited by the tides. Fortunately we’re into neap tides now, which is a mixed blessing. The highs and lows won’t be as extreme as they were a week ago, resulting in less time that the crew can work on the beach (bad) as well as tides that are less likely to wash flotsam off the beach and back into the water (good).

The last I heard, the clean-up at the Terrace Point site was supposed to be completed by Saturday. That’s tomorrow. Today (Friday 17 August) I went out to the point and had a nice chat with the security guy, who updated me on the progress. He said the crew removed the rest of the boat and a fuel tank yesterday. And the site of the original wreck is now clear of large pieces of boat:

Site of the shipwreck of the F/V Pacific Quest
17 August 2018
© Allison J. Gong

There is one more fuel tank on the other side of that point, which the salvage crew will work on removing this evening at 20:00h when the tide will be low again. There are also people picking up debris on the Natural Bridges side of the point.

Fuel tank of the F/V Pacific Quest
17 August 2018
© Allison J. Gong

It isn’t easy, working in these conditions, and once the immediate hazard of additional fuel discharge was abated the clean-up seems to have made slow but steady progress. Most of the flotsam is already gone, except for the inevitable little pieces that will get missed in this initial burst of clean-up activity. This Sunday, a week after the initial shipwreck, a visitor to the beach will not know that anything of interest happened here. Those of us who live and work and study here will remember, though.

Flotsam

Posted on by Allison J. Gong

This morning I went out on what will probably be my last low tide of the season. We don’t get any good (i.e., below 0 feet and during daylight hours) until November, so it’s time to hang up the hip boots for a few months and work on other things. I had planned to go to Natural Bridges even before the shipwreck incident, and since the wreck is right next to Natural Bridges I thought it would be good to check on how much debris is washing up at a site I visit frequently.

I’m sure that most people are familiar with the phrase “flotsam and jetsam”, referring to pieces of miscellaneous stuff. I had to look up the terms to remember the difference between them. Flotsam is the stuff that floats on the water and gets washed up when a ship or boat wrecks, while jetsam is the stuff that is deliberately thrown overboard to reduce weight (say, to increase speed). What I would be seeing today is flotsam.

It was so sad. I’m not naive enough to have thought there would be no debris, but I wasn’t sure what to expect–big pieces? small pieces? identifiable pieces? At this point I hadn’t checked on the status of the boat yet and didn’t know how much of it was still grounded off Terrace Point.

The first thing I saw was something (I don’t know what) that had been dragged up the beach. It looks like a piece of equipment tangled up in a big piece of fabric, maybe a t-shirt? More than one t-shirt?

14 August 2018
© Allison J. Gong
14 August 2018
© Allison J. Gong

The first recognizable thing I saw was, oddly, a bulb of garlic. I don’t know why it was surprising. Obviously, people who spend a lot of time on boats eat on boats, and some of the flotsam from any shipwreck is going to be food, right? Another food item that washed up was a vacuum-sealed package labeled “Emergency Ration”.

14 August 2018
© Allison J. Gong
14 August 2018
© Allison J. Gong

Another everyday household (boathold?) item was a tube of sunscreen. I also saw a few plastic utensils, which may or may not have been from the shipwreck. Unfortunately there’s always some plastic detritus on all of our beaches these days, a legacy from decades of single-use plastics being literally thrown to the wind to end up as garbage in the oceans and elsewhere. Hard to believe that “out of sight, out of mind” used to be the universal prevailing outlook, isn’t it? Here in California and elsewhere there is much greater awareness in recent years that plastic in the environment never really goes away. It just breaks down into smaller and smaller particles, which can enter the food chain at lower and lower trophic levels. That’s a whole other story to talk about. Maybe some day I’ll be brave enough to tackle it.

Stuff from the wreckage was strewn across all of the intertidal benches and pocket beaches at Natural Bridges. This is looking towards Terrace Point, where remnants of the boat are stuck in the ground:

14 August 2018
© Allison J. Gong

When I was watching the crews pumping fuel off the wrecked boat yesterday, I saw two survival suits washing around in the surf, and wondered where they would end up. I saw one of them this morning, along with two life vests.

14 August 2018
© Allison J. Gong
14 August 2018
© Allison J. Gong

And a respirator:

14 August 2018
© Allison J. Gong

And an entire boat. This is the inflatable Zodiac that had been tied to the roof of the cabin of the F/V Pacific Quest.

14 August 2018
© Allison J. Gong

I don’t know what Marine Compound is, but a bottle of it washed up, along with what looks like a piece of insulation:

14 August 2018
© Allison J. Gong

And of course there was styrofoam. Styrofoam is insidious stuff, because it doesn’t remain intact long enough to be removed as big pieces, but instead immediately starts breaking down into small bits that will soon enough become the nurdles that are such a problem for marine life.

14 August 2018
© Allison J. Gong

Already the pieces of plastic and styrofoam were getting smaller. I don’t know what the blue stuff is; another form of styrofoam, maybe?

14 August 2018
© Allison J. Gong

Not all of the flotsam has washed onto the beaches and rocks. There is still a significant amount floating in the water, to be transported to other sites near and far. There’s even flotsam in the tidepools. Wood, fiberglass, and plastic are all included.

14 August 2018
© Allison J. Gong
14 August 2018
© Allison J. Gong

After leaving the intertidal I went to the marine lab to see what things looked like from the cliff about the wreck. The entire front part of the boat is now gone, and the only part remaining is the aft end containing the two heavy engines.

Wrecked F/V Pacific Quest
14 August 2018
© Allison J. Gong
Engine of the wrecked F/V Pacific Quest, viewed from above
14 August 2018
© Allison J. Gong

From the cliff you can better see how widely dispersed the flotsam is. It isn’t concentrated in any particular area but is everywhere, in pieces small and large.

Debris from the wrecked F/V Pacific Quest strewn over the intertidal at Natural Bridges
14 August 2018
© Allison J. Gong

There is some good news. All of the fuel was removed from the boat so there’s no further danger of additional chemical pollution into Monterey Bay. The salvage crew did remove some of the debris from the immediate area around the wreck, and tomorrow the engine will be removed by crane up the cliff. It’s going to be an impressive and LOUD undertaking, starting very early in the morning.

Taking the long view, this is one of a great many acute insults to the marine environment. The ocean is resilient to some extent, but our actions are causing changes that affect the entire biosphere. I’m having a hard time finding a silver lining in this shipwreck. I certainly never wanted to bear witness to an environmental disaster on any scale. And while in the grand scheme of things this is a small localized event, it feels pretty momentous to me.

I’ll leave you with this more positive photo. Flotsam aside, it was a beautiful morning.

Approach to tidepools at Natural Bridges
14 August 2018
© Allison J. Gong

$hit happens

Posted on by Allison J. Gong

Very early in the morning of Sunday 12 August 2018, the F/V Pacific Quest ran aground near Long Marine Lab. I found out about it because the lab facilities manager sent out a global e-mail telling us that a boat had wrecked and telling us that the seawater pumps had been turned off just in case the boat leaked any fuel or oil. The e-mail came through at about 06:00h. By the time I got to the lab at 10:30 the pumps had been turned back on. After I made sure all of my animals were okay, I moseyed over to the cliff to see what I could see.

The tide was coming in, to a high of 5 feet at 12:42h. The captain had dropped an anchor before leaving the boat after it got stuck on the reef ledge, which kept it from drifting away and becoming a hazard to other vessels on the water. The rising tide had lifted the boat from the ledge to land between the ledge and a small rock island. The swells picked up the boat, but the hull had been damaged and she was taking on water. The captain was the only person on the boat, so there was no loss of human life in this incident.

The F/V Pacific Quest, shipwrecked at Long Marine Lab
12 August 2018
© Allison J. Gong
The F/V Pacific Quest, shipwrecked at Long Marine Lab
12 August 2018
© Allison J. Gong

The swells were continually breaking over the bow, flooding the cabin and washing flotsam off into the ocean.

The F/V Pacific Quest, shipwrecked at Long Marine Lab
12 August 2018
© Allison J. Gong

A Vessel Assist boat was there when I arrived and was stationed just inside the kelp bed. They put two guys into the water, who swam to the Pacific Quest and attempted to attach a tow line.

12 August 2018
© Allison J. Gong

Ultimately, however, they decided that conditions were too dangerous for the Vessel Assist boat to tow away the Pacific Quest. The hull had been breached and the boat had taken on a lot of water, making her too heavy to be towed safely. Besides, the Pacific Quest is a 65-foot fishing boat, making her about twice as long as the small Vessel Assist boat. The two guys swam back out to the rescue boat and they drove away.

Meanwhile the tide continued to rise, and the Pacific Quest was clearly floating, albeit listing to port and heavy in the bow. I think that if she hadn’t been anchored to the shore she would have floated away. Could she have been safely towed away at this point? I don’t know. I do know that no other actions were taken to try to remove her.

I returned in the late afternoon for the high low tide, and it was clear that the boat was resting on the sand between the ledge and the small island. The continued bashing against the rock had put a big dent in the starboard side, no doubt worsening the hull breach.

The F/V Pacific Quest, shipwrecked at Long Marine Lab
12 August 2018
© Allison J. Gong

With the boat stationary on sand, a salvage crew finally started taking action. They removed the remaining debris from the deck, including the fuel tank from the inflatable zodiac, and attached some lines.

Salvage crew aboard the shipwrecked F/V Pacific Quest
12 August 2018
© Allison J. Gong
Salvage crew aboard the shipwrecked F/V Pacific Quest
12 August 2018
© Allison J. Gong

Someone had determined that although the hull had been breached the fuel tanks were undamaged and were unlikely to release any diesel fuel or other oil into Monterey Bay. At the end of the day yesterday the plan was for the salvage crew to tie the boat down and keep her from drifting away after the evening high tide, and start pumping off the fuel at low tide this morning. Then the salvagers could work on removing the boat itself. I couldn’t figure out exactly how they would remove the boat, but hey, I’m only a marine biologist, not a marine salvager. As long as the fuel tanks didn’t rupture, things would be juuuuust fine.

So much for plans. The caretakers reported smelling diesel fumes at 21:30h last night, and shut down the seawater intake pipes. Turns out the boat had broken up during the rising tide, with at least one fuel tank ruptured. Fortunately, if that’s a word that can be used in this situation, the shipwreck is downstream from the seawater intake. The pumps were shut down for a few hours this morning and we’re on short rations, but there doesn’t seem to be a significant amount of diesel in the seawater system.

I was working the low tide this morning and had an appointment afterward, so I didn’t get to the lab until about noon. The boat was well and truly broken up by then, into two large pieces and a great many smaller ones. The pieces of wood, plastic, and fiberglass were already dispersing with the currents.

Flotsam from the shipwrecked F/V Pacific Quest
13 August 2018
© Allison J. Gong
The F/V Pacific Quest, broken on the beach at Long Marine Lab
13 August 2018
© Allison J. Gong

The good news is that the salvage crew had finally started pumping off the fuel remaining on the boat. As of 17:17 today the crew reports that they should be able to offload all of the fuel before the next high tide tonight. With any luck, they’ll be able to finish the job and we can carry on as usual without anymore seawater interruptions. At this point I don’t know what plans, if any, are in place to remove the boat parts on the beach. The various organizations at the marine lab are parties of interest, but none have the responsibility of cleaning up this mess. We just have to live and work with it.

Life preserver from the shipwrecked F/V Pacific Quest
12 August 2018
© Allison J. Gong

UPDATE: As of 19:00h on Monday 13 August 2018 all fuel has been pumped out of the Pacific Quest. The major risk of chemical pollution into Monterey Bay has been abated. The next stage of recovery is the retrieval of debris from the beach and ocean.

Rodent patrol

Posted on by Allison J. Gong

About a week ago, as part of yearly summer fire prevention, some of the fields at the marine lab were mown. After this happens many of the little critters living in the dried grasses are left homeless and become relatively easy prey for predators of all sorts. Since the mowing I had been seeing a great blue heron hunting in the field, and it took me until the day before yesterday to remember to bring the camera with me. Fortunately it was overcast that morning and the heron was there!

Great blue heron (Ardea herodias) hunting for rodents at Long Marine Lab
28 July 2018
© Allison J. Gong

I watched the heron hunt (unsuccessfully) for a while, then my attention was drawn to a much more dynamic avian predator. A juvenile red-tailed hawk, possibly the one that grew up and fledged from the nest across the canyon from my house, flew overhead and perched in a cypress tree. From there it had a birds-eye view of the field, and it didn’t take long for it to spot a late breakfast. The heron left, squawking loudly to protest the interruption to its hunting.

Juvenile red-tailed hawk (Buteo jamaicensis) with prey, at Long Marine Lab
28 July 2018
© Allison J. Gong

The hawk actually skinned the rodent before eating it. . .

Juvenile red-tailed hawk (Buteo jamaicensis) consuming prey, at Long Marine Lab
28 July 2018
© Allison J. Gong
Juvenile red-tailed hawk (Buteo jamaicensis) consuming prey, at Long Marine Lab
28 July 2018
© Allison J. Gong

. . . and then it ate the skin!

Juvenile red-tailed hawk (Buteo jamaicensis) consuming skin of prey, at Long Marine Lab
28 July 2018
© Allison J. Gong
Juvenile red-tailed hawk (Buteo jamaicensis) consuming skin of prey, at Long Marine Lab
28 July 2018
© Allison J. Gong

The hawk did not linger on the ground after eating its rodent prey. It flew back across the road up to the cypress tree again. I got lucky and managed to catch a few shots as it flew by.

Juvenile red-tailed hawk (Buteo jamaicensis) in flight
28 July 2018
© Allison J. Gong
Juvenile red-tailed hawk (Buteo jamaicensis) in flight
28 July 2018
© Allison J. Gong
Juvenile red-tailed hawk (Buteo jamaicensis) in flight
28 July 2018
© Allison J. Gong

Of course, I have no way of knowing if this young hawk is indeed the one we watched grow up. I’m reasonably certain that the marine lab is in the parents’ foraging territory, as I’ve watched them leave the nest site and fly towards the lab. At some point the juvenile will have to disperse away from its parents and establish a territory elsewhere. In the meantime, it, along with other birds of prey, will have easy pickings in the fields. This has been a banner year for wood rats and gophers (ugh!), which means there should be plenty of food to go around.

By the way, the heron did not catch any rodents while I was watching. It did not return after the hawk arrived.