Algae and medusae

Spring is still lagging behind, predictably. I went out this morning to find Crepidula eggs to hatch for experiments, and although the eggs are there, they aren't anywhere near hatching. So back to waiting and trying to farm eggs in the lab.

Stuff is definitely happening in the field, though. Most notable since my last trip was a serious explosion of macroalgae. This site is full of really thick growths of large algae through the late spring and early summer, until it gets really hot. The algae is sort of a pain -- it's probably two inches deep to wade through and covers the snails that I'm looking for. At least I was out in boots today, because walking through two inches of algae in my sandals is a little icky.

A thick bed of algae on the beach. Normally there's just sand and small cobbles here.
The small 'creek' that has been created by flowing water allows you to see just how thick the mat is.

I did find some snail eggs from other species, including this nifty sand collar.

A sand collar, or moon snail egg mass.

But by far the coolest thing I saw today was a jellyfish (species unknown). I noticed something funny-looking floating in ALL OF THE ALGAE and at first I just thought it was a dead Chondrus or something. Lots of the algae turns white when it dies. But this seemed to be weirdly radially symmetrical and, upon further inspection, to have tentacles.

Lucky I had my rubber gloves, because I do usually draw the line at handling unidentified jellies.

Jellyfish!

I was surprised to see this guy so early in the season. The jellies get super-abundant around here by August, but are pretty rare in May. It's also unusual at this particular site to see them washed near shore, though other places I work they are pretty common.

Scyphozoan jellies have a totally awesome life cycle. It has two basic stages: the medusa form (think typical jellyfish) and the polyp form (think sea anemone, to which they are related). A medusa makes gametes that turn into a larva, which grown into a polyp, which then buds into little medusae. Sound complicated? It sort of is. Here's a picture to help.

Life cycle of a scyphozoan. Photo from Wikipedia, with more details.

My favorite part of this life cycle is strobilation, step 11 in the figure above. Here's a fabulous video. And another one. Something that doesn't come across in the not-to-scale diagram but does in the video is just how small the polyps and strobilae are. They really are fascinating. I haven't ever seen a strobila in the field, but it's on my invert life-list.

For today, though, I'll settle for an adult scyphozoan. And maybe some larval Crepidula, if that's not too much to ask for.

Today's jelly, adrift in the algae. 

Science reading 1: Lazy Point

And now for something completely different. No new pictures this week, but I thought I would honor a request: the lovely Carolyn, a high school acquaintance of mine and the literary blogger at Rosemary and Reading Glasses, would like recommendations and reviews of science books.

As it happens, popular science books are among my favorites, so I'm happy to oblige. When I got the request, though, I wasn't quite sure where to start. Aldo Leopold? Rachel Carson? or newer authors like Carl Zimmer and David Quammen? or Stephen Jay Gould? or Neil Shubin? Hopefully I'll get to all of these and more.

But to start, someone who is a contemporary Ph.D. scientist and conservation activist, as well as a relatively prolific writer, filmmaker, and compelling speaker: Carl Safina. Dr. Safina got his Ph.D. at Rutgers studying the ecology of seabirds, and since then has become one of the most public advocates for seabirds, marine mammals, fish, and the marine realm in general. He's also got an appointment at Stony Brook, and I've been fortunate enough to hear his talks and take a course he co-taught in science communication.

Dr. Safina has written several books, and his first, Song for the Blue Ocean, is supposed to be quite stunning. I say 'supposed to be' because my copy is sitting on my bookshelf, embarrassingly untouched. I can wholeheartedly recommend his Eye of the Albatross, in which he travels to an albatross colony in the northwest Hawaiian islands to study the world's largest seabirds.

Those of you familiar with A Sand County Almanac may
recognize the general zeitgeist of the cover of the paperback edition.

But the book I want to talk about today is one of his most recent, The View from Lazy Point: A Natural Year in an Unnatural World. The structure of this book is based on an ecological classic, A Sand County Almanac by Aldo Leopold. Safina goes month by month through the year, discussing the natural world around his house. I was drawn into the book in part because the locations he describes and the animals he sees are very close to my house, but I don't think that would be a deterrent for anyone, no matter how far from Montauk you might be.

One of the scenes that has stayed with me in the years since I read this is the one where the author encounters poachers of horseshoe crabs. He does an excellent job describing the horror of these crabs being taken en masse, but also explains the economics and politics behind why this happens, as well as the ecological consequences (beyond the mortality to the crabs, there are potential consequences to seabird species that depend on their eggs). It is this description that I return to each time I am out on the shore and fortunate enough to see a female crab buried in the sand.

Interspersed with these snapshots from Lazy Point are chapters where Safina travels to the tropics, the poles, Alaska, and so on to see the global consequences of human impacts on the ecological world. The result is the impression that everything that we do to affect the planet matters, both close to home and far away (even in seemingly untouched, pristine habitats). To quote from the opening pages:

So this story is also about the tension created when those things mistakenly called the "real world" -- though they are entirely artificial -- continually intrude on the real real world. In a real place, the mysteries of ages pile on thick with enduring truths and complex beauties. 

There is no place, in other words, that is safe from our influence, and no place without its own natural beauty. And later, in those same opening pages, while contemplating migrating seabirds, where they go, where they have been:

They all remind me that the world is both much bigger than Lazy Point, and yet surprisingly small. "I have traveled a great deal in Concord," reported Henry David Thoreau. And how much greater he might have thought his travels if he'd lived at Lazy Point instead. The coast and its migrants bring to Lazy Point a much bigger picture than any map of the place suggests. I sometimes tell friends it's possible to see the whole world in the view from Lazy Point.

 We are all interconnected with the natural world, and our actions have consequences far away from where we can see. It is a familiar narrative, but the details in this book drive it home.

Hacking spring: what to do when things are slow in the field

Spoiler: spring progress this year is slow. The cyprids continue to settle.

An oyster shell (Crassostrea virginica) covered with newly settled barnacles.
The redder dots are the younger larvae, and the gray ones are slightly older. 

A cement wall at my field site. It's hard to tell in this picture, but the reddish tint that you see between the large white pebbles is entirely due to a dense covering of newly settled barnacles.

The snails are just starting to come out in the field, and the water is warm enough that the Crepidula are finally brooding eggs. That means that they should be ready for experiments in a few weeks. Until I can reliably collect larvae in the field, I've been making do with what I can farm in the lab. That has meant collecting animals and bringing them up to room temperature, which triggers them to lay eggs. If I keep the females in clear plastic cups, I can watch the embryos develop and collect the larvae when they are ready to hatch.

Developing C. fornicata egg mas in a plastic lab cup. The female is probably about 30 mm long, and you are looking at her underside (ventral side). The solid arrow indicates the egg mass, which is full of little yellow dots. Those are the individual eggs. They are just laid, and have not really started developing yet. As the embryos develop and grow into little larvae, they will change color -- that's the signal I'm looking for to indicate their readiness to hatch. The dashed arrow is the foot of the animal. The egg mass is obscuring the head of the animal; she is brooding the eggs between her neck and the cup. 

This is a nice, convenient way to get lots of larvae for experiments year-round. The animals require extra care in the cups (each one needs to be fed daily and given clean water every 2-3 days), but sometimes this also means that I can get developing larvae as a side effect when working on other experiments with these adults in cups.

The barnacle life cycle: a photo essay

In my last post, I talked about the many settling barnacle cyprids that indicated the arrival of spring around here...but without any good photos of what these larvae actually look like. So here is a brief post on the life cycle of a barnacle.

Barnacles are crustaceans, the same group that contains the more familiar crabs and lobsters. This means, among other things, that they have an exoskeleton and jointed appendages. But they live attached to rocks, covered with a calcareous test, with no sign of those appendages (at least when the tide is out!).

Adult barnacles. Photo from Wikipedia.

When covered with water, though, their jointed legs (cirri) extend from those tests and catch phytoplankton that floats by. 

Feeding barnacles. The feathery things are the cirri. Still from Wikipedia.

Because the adults live cemented to rocks, it is the larvae that do most of the dispersing. Barnacle larvae go through many molts in the plankton as a nauplius.

Nauplius larva. Still Wikipedia.

Then, when they are ready to settle and metamorphose, they turn into cyprids. It is these cyprids that search out a place to live, contacting various substrates and searching for the right physical and chemical conditions before metamorphosing into their adult form. Barnacle settlement is ubiquitous in these parts, and relatively easy to settle, so it has been a mainstay of larval ecology for decades. We arguably know more about how and why barnacles choose their settlement sites than any other taxa. It depends on a variety of physical factors (for example, they preferentially settle in cracks on rocks) and chemical factors (they are attracted to proteins produced by conspecifics).

Here is one of the cyprids I collected this weekend.

A cyprid larva. Many lipid droplets at the anterior end provide buoyancy and energy for the larva.

I have thousands in the lab right now -- if I give them the appropriate settlement cues, I'll be able to watch them metamorphose, and the barnacle life cycle will be complete. (Well, except for gamete production and mating...perhaps left for a future post?)

All of a sudden, spring

I had a post all planned bemoaning the fact that spring is still very far away in these parts. In previous years, the snails are often laying eggs by this date on the calendar. Given the winter we've all had, it's no surprise that they are still nowhere to be seen, let alone reproductive.

I went to the beach on Tuesday (the day after a freak snow) to bring snails back to the lab for some experiments, and this is what it looked like.

The beach on a not-quite-spring morning.
The profile of the beach is still very steep due to winter erosion, and there were very few signs of life.

Berms of dead Crepidula fornicata shells were everywhere on the beach.
That's typical for late winter around here.

But today everything seemed different. It was the first day I was able to go exploring in shirtsleeves this year, and I went down to the harbor to get seawater for the lab. We don't have running saltwater in my building, but we are close enough to the shore that I can go get it when I need it. I found this.

Cyprids! Each of the brown blurry dots in the water is a larval barnacle, looking for a place to settle.

Cyprids, not yet metamorphosed, that have attached themselves to a dead blade of grass.

Cyprids are the last larval stage of a barnacle, and their job is basically to find a place to live as an adult before metamorphosing. They look like little beans with eyes and antennules that they use to sense physical and chemical cues on the substrate. They tend to settle gregariously, preferring to be near other cyprids and adults of the same species.

These cyprids have metamorphosed and become juvenile barnacles. They are probably not long for this world, because this dead blade of grass is not a stable habitat and will almost certainly wash away before the barnacles become adults.

The cyprids are the first clear sign of spring around here, as reliable as the many signs used in the terrestrial world to indicate that we are finally through the winter. So in the few short days since my field trip on Tuesday, things have turned a corner and are looking up. Field season is imminent.

Marine diseases, sea stars, and why it might matter

A sea star that I found on a collecting trip in September.

 It's deep winter here, the kind that has us shoveling new snow more days than not and the animals on the beach dealing with all sorts of ice and snow, so I have more time for the blog than at other points during the year. It reminds me of my childhood winters elsewhere in the country much more than a normal winter here on the coast. So hi again. This time with content.

There are several conservation issues in the marine realm that make the news with some regularity. Climate change, of course, and overfishing, and the relative new kid, ocean acidification. But the latest issue that's making headlines is a catastrophic decline in sea star populations along the Pacific coast of North America. This decline is sudden and unexplained, and although the evidence is consistent with a disease, no one really knows yet just what that disease might be.

Yes, marine invertebrates get diseases too. Scientists really know very little about what causes diseases in the marine realm, but we do have examples from coral, lobster, and oysters, just to name a few. It seems like we need to add sea stars to that list. There's even some indication that the frequency of diseases has been rising of late, possibly due to changing climates.

Here are links to places around the web that have explained the current sea star issue better than I can:

PBS recently produced a great clip on News Hour about the problem that I strongly encourage you to see. The scientists interviewed here are ones that I have met and interacted with, and people I really respect. It's neat to see them on TV. In fact, one of them has made a previous appearance on this very blog for her work curating the collection of glass invertebrates at Cornell University.

More scientific information is available here from UCSC.  This site shows you the different stages of the disease, and even includes a form for you to report sightings of diseased sea stars (for anyone who might be reading this in the affected Pacific Coast area).


And lastly, here's another great blog post about the subject.

But why does any of this matter? Well, for one thing, sea stars are a group of marine animals that people feel some sort of connection to. They are iconic images of the sea, popping up in jewelry, home decor magazines, and children's cartoons. But they are also important animals in the communities where they occur. Six months ago, I wrote about intertidal zonation on rocky shores. Sea stars are crucial players in keeping mussel beds under control by eating mussels (the stars are pretty voracious predators). In fact, they are the defining example of a keystone species: one that has a disproportionate effect on the community relative to its abundance. Remove the stars from an area, and the whole community structure will change.

So the disappearance of stars due to a mystery disease is pretty troubling. Hopefully scientists can at least figure out what is causing the decline while there are still sea stars left in some of these areas to save.

The underside of the same star. Note the tube feet that they use for moving around (operated by a hydrostatic skeleton) and the mouth of the organism, which is in the center where all of the arms converge. Sea stars eat by ejecting one of their stomachs and digesting their prey before ingesting it.

In the bleak midwinter

My field site under six inches of snow.

The high tide line becomes easily visible in the snow: it is where the water has washed the snow away. The beach itself looked normal, until I looked closely.

Ice in the intertidal. It wasn't even that cold this morning (right around freezing). The local flora and fauna are frequently affected by ice in this area, which will scour the rocks bare and create new habitat.

It was beautiful this morning, above freezing, sunny, and not windy. A nice break in what is promising to be a very snowy week. Conveniently (since I need the snails), this corresponded to a very low spring tide. Because many of my snails have been frozen off the rocks (see the third picture) I had to venture out into deep enough water that the snails had not been frozen yet this winter.

Update with snails

I know it's been forever since I updated. The semester started and hit me like the proverbial train, and since then it's been nothing but teaching and research at full-tilt. There was a collecting trip in there, and several experiments started, and a couple finished. I gave an invited talk for the first time at another university, and may have inspired a student to start doing research in ecology.

Here are a few select photos from the last two months:

A tidepool full of Crepidula plana and surrounded by barnacles. Photo taken in September on a collecting trip.

Seaweed (probably Sargassum washed up on a beach in Florida. The seaweed was full of little critters living on and in it, and at night something was bioluminescing in the seaweed clumps. Photo taken in October on a for-fun trip. I am astonished by the colors every time I see this shot.

My local field site, sunset, early November (the day before the end of daylight savings).

What inspired me to come back to the blog today was nothing that I have done, but rather this post from Rachel Collin's lab in Panama (I've mentioned their work with Crepidula before). One of the grad students in the lab has gotten actual video footage of mating Crepidula, and the videos are up on the lab blog.

Go. Check it out. It's really quite amazing.

Summer photos 8: a horseshoe crab

Sunrise in the field on a flat calm spring tide.

A horseshoe crab, Limulus polyphemus, surrounded by many many mud snails.

Well, this is it, the last week before school starts. And then I will be in the awful part of the year where I am juggling lab, field, and school responsibilities. Before that happens, I went out in the field to collect more snails. It was a beautiful morning, and I was there just as the sun was breaking over the horizon. It was a dead-calm day, as you can see in the first photo up there.

Among the many interesting things that I saw was this female horseshoe crab (Limulus polyphemus). These guys are really amazing. They are not really crabs (not crustaceans), but are more closely related to arachnids. They have remained morphologically the same for hundreds of millions of years, and are different than anything else I have seen on the shore. There's just one species in this part of the world, and I'd never seen it before moving to where I am now. But here they are all over, and I have collected molts of all sizes. One of the coolest sights on the beaches here is in May/June during the spring tides, when they come up onto the beaches by the hundreds to mate. I often barely miss stepping on them as I am walking around in the intertidal. This female got caught high on the shore at low tide, so she dug herself in to stay damp until the water comes back in.

Horseshoe crab blood has many different medical uses, and their eggs are eaten by many species of migrating shorebirds on the east coast of the U.S. Unfortunately, due to heavy use of the species as bait and to habitat destruction, their numbers have been declining for decades.

A deceased horseshoe crab with C. fornicata and C. plana attached. The size of the C. fornicata indicate that they were probably growing there while the crab was still alive, impeding respiration and locomotion. Photo by J. Browne.

They're also very cool because of how different they are from any other group that we study in invertebrate zoology. One of the things that I will miss when I leave this area is seeing them in large numbers, often with their carapaces bedazzled with Crepidula shells.

Summer photos 7: the Bay of Fundy

I'm taking things a little out of order today, chronologically, because school starts oh-so-soon and I want to make sure that I get this post written before it does.

In late July, I went on a snail-hunting trip to the northern end of Nova Scotia (Cape Breton). Those photos will be forthcoming. But what matters for today is that this entailed an epic drive across the northeastern bits of both the U.S. and Canada. I had constraints on my time due to things happening in the lab, but also on a more immediate basis because of the tides. Since I can only look for snails at low tide, and low tide is only at a particular time, this means that I often have more time than I need to drive from point A to point B on any given day, leaving me time to do a little bit of sightseeing.

On this trip, I took a short detour through Fundy National Park in New Brunswick. I very sadly did not have time to explore either the bay or the hiking trails, but it was a nice drive.

The Bay of Fundy is notable for having the highest tides in the world. What that means is that the difference between high tide and low tide is larger there than anywhere else (an average difference of 47.5 feet during spring tides). There are also whales in the bay, and tidal bores where the rushing tides run into rivers and cause the rivers to change direction at certain times of the day. For a marine ecologist (or at least for me), this is something of a pilgrimage to go see.

Fundy National Park, New Brunswick. I'm not sure when in the tidal cycle this was, but somewhere in the middle.

Tidal flats at Fundy National Park.

Low(ish) tide at St. Andrews, New Brunswick. At high tide the water would be up near the pier, which is probably 10-12 feet high. Also note the abrupt change in the weather from the previous day. This made for more unpleasant driving.

Another shot of the Bay of Fundy, this one from a previous trip to Quoddy Head, Maine (the easternmost point in the US. This was taken only 1-2 hours before high tide (there's 6 hours between high and low tide), and by the time I left the park all of this rockweed was underwater.

I still have not had the opportunity to really explore the Bay of Fundy. Someday I definitely want to go see its more famous landmarks, look at the whales, and really explore its lower intertidal. For now, I'll have to content myself with pretty views from pretty high up on the shore.