More fun and cagery

When we did our first few dives at Baltra, I set up a single cage for my Pentaceraster starfish as a test to see if (1) the cage would hold up against the current/surge; and (2) if the cage would keep my Pentaceraster enclosed. We visited the site again on the final day of the research cruise, and I was very glad to see that the answer was yes on both counts (with n=1, but I'm okay with that...)

One week later: Inti from the Darwin Station examines my still-caged Pentaceraster.

Now that I know this kind of cage can work as an enclosure/exclosure, I'm going ahead and scaling up cage production in preparation for deployment next week. The test cage had a diameter of 0.5 m, which is a little small for a Pentceraster that can have an arm radius of ~20 cm. The new cages are 1 m in diameter, and I am constructing them from old caging material previously used to enclose sea urchins (yay for recycling old and fouled research gear). I have been working with wire cutters and cage wire and lots and lots of cable ties over the past 3 days.

Fun with cages. About 10 minutes after this picture was taken I switched to actually wearing work gloves.

I also made a few friends, and learnt that baby marine iguanas are small enough to fit through the holes of my cages.

This little guy came by and visited me several times.

Any kind of tedious and/or repetitive job needs a work song, so here is my cage building song:

I've Been Making Starfish Cages
(to the tune of "I've Been Working On the Railroad")
I've been making starfish cages
For hours every day
I've been making starfish cages
And the time just slips away
Hope my predator inclusions
Show me interaction strengths
Hope my starfish cages weather
The storms and surge and waves!

The camera sees all: Manta ray at Baltra

Over a week after one of our early dives at Isla Baltra, I review the video from the GoPro recordings and see this. None of us knew it, but we were diving with a manta ray. I guess we should look up from working on the bottom once in a while... :)

Does fish diversity matter?

Previous work out of the Witman lab has looked at how sea urchin diversity affects processes like grazing rates in the Galapagos. Now the focus is shifting higher up the food chain to the things that eat sea urchins. More specifically, does the diversity of urchin predators affect the intensity of predation on urchins? Are there interactions between the different urchin predators that may alter predation rates? My own project aims to figure out to what extent seastars such as Pentaceraster are a part of this predation. The other obvious suspects would be predatory fishes.

Whodunit.

To get some preliminary data on the diversity of fishes (with a special interest in species that could potentially eat urchins), we've been deploying a bunch of Hero GoPro cameras at multiple sites around the central Galapagos archipelago to record 3-4 hours of continuous video data on the fish that are present. These little wearable cameras were originally made for filming high-definition extreme sports videos, but work extremely well as our underwater data-collectors - we've made little stands for them that weight them down on the rock (usually we also stick a few rocks on the stand for greater stability).

Deploying the camera system

GoPro in its natural habitat

During our 5-day research cruise, we collected fish diversity data from 11 different sites, deploying 2 cameras per site for a minimum of 1 hour continuous video data per camera. Video data are easy to collect and accumulates quickly, but it will probably take many more hours in the fall and spring to analyse fish diversity from the raw data.

Here is a one of the more exciting excerpts from Rocas Cousins, a site on the north side of Santa Cruz. How many fish species can you spot? (If you're not too distracted by the charismatic trio of ray, sealion and turtle...)

On having five fingers

Today I watched a juvenile marine iguana sitting on a rock, and thought about the simple beauty of a pentadactyl limb.

Salty sotong returns

Back from a five-day research cruise around the central Galapagos archipelago. I write about it briefly on the Brown Global Conversation blog, but more will be up here soon. In the meantime, here is my favourite photo from the trip:

My first frogfish!

Here is a picture of it from the top. It was lying in an urchin hole in the rock wall at Daphne Menor, which is just north of Santa Cruz island.

Project Pentaceraster

I wrote before that my research project here involves figuring out the basic feeding relationships of starfish in the Galapagos subtidal system. This fits into a larger framework of understanding the connections between different species in this system, including economically important species such as carnivorous fish and Leslie's Hexaplex snails, and ecologically important species such as grazing sea urchins and herbivorous fish.

A sampling of starfish species, clockwise from top left: Nidorellia armata (chocolate chip star); Phataria unfascialis (blue sea star); Pharia pyramidata (yellow spotted star); and the ever-awesome Pentaceraster cumingi (Panamic cushion star)

I am focusing my efforts on Pentaceraster for now because we have preliminary evidence that it eats sea urchins, making it a potentially important link in the food web. It is also quite abundant, so it makes up a substantial amount of standing biomass. On our dives, I have been overturning Pentaceraster along the transect to (1) take measurements of their size using my amazing starfish-measurers - I've further modified them a little by taking off a weight and adding a clip to the end; and (2) recording what they are munching on, if anything. Pentaceraster eats by everting its stomach onto its lunch, so it's easy to tell if it is feeding when I overturn it. It is not as easy to ID its lunch as it pulls its stomach back in.

Measuring the radial length (=length of one arm) of a Pentaceraster star. The transect tape is just visible in the top right.

Overturned Pentaceraster retracting its stomach. I go digging through all the bits and find out exactly what's in its mouth.

We also ran a cage trial with a recycled cage from an old experiment. Eventually I am planning to use larger cages to test the effects of including vs. excluding Pentaceraster from an area, but I need to know how well these cages will hold a starfish. We'll be back at this site next week, so I'll be able to see if Mr Pentaceraster has escaped from my setup.

Setting up the cage with Jon.

Final cage setup. One Pentaceraster and five Eucidaris sea urchins (two are clearly visible).

Subtidal again

Over the past couple of days we did our first eight research dives in the Galapagos. I was really excited to finally get back in the water (after being dry for 10 days...snorkelling doesn't really count) and start working. The water temperature here has been around 24-27ºC/75-80ºC which is the coldest I have ever seen in the tropics. But coming from 7ºC/45ºF dives in New England, it was marvelous.

Starting the day with what Jon calls "stuffing your advisor into his wetsuit"

Unlike my New England research sites, all Jon's sites in the Galapagos are only accessible by boat, so our underwater time is much more limited. So we aim to get as much out of our underwater time as possible, which means we are usually doing multiple things on each dive. Jon does his long-term monitoring of permanent wall transects and corals at each site, while Leslie and I work on our individual (starfish and Hexaplex snail) projects.

Working the permanent transect at the Guy Fawkes site.

Leslie taking shell measurements of Hexaplex snails. Plastic calipers courtesy of Sal and the Three Seas Program :)

I finally met one of the focal species of my project up close, face-to-aboral surface. Pentaceraster cumingi, the Panamic cushion star, is a large and fairly abundant seastar that hangs out mostly on the sand, rubble and rock-sand interfaces underwater. I'll be collecting observational data on its size distribution and feeding, and also running caging/tethering experiments to figure out its effects on other organisms in the ecological community. I started on this stuff yesterday - more on this in another post.

Mr. Pentaceraster says hi.

And of course, every research dive has its share of distractions. But the ones in the Galapagos are a lot more flamboyant than the ones in New England...

o hai. im in ur transectz, scaring ur fishz

Kludgey science

Over the past couple of days we have been scavenging bits from Jon's piles of old research equipment at the Charles Darwin research station for use in our experiments this summer. If you've worked somewhere for 10 years I guess you accumulate lots of stuff, particularly if you're a macro-ecologist and like doing large scale things. Leslie's project aims to create a demographic model for an ecologically important predatory snail species, Hexaplex, and compare how its populations behave in areas where it is fished, versus areas where fishing is prohibited. To figure out the different parameters of the model (e.g. growth rates, mortality rates for different sizes of snail), she needs to tag a bunch of Hexaplex in their natural habitat and track them over time. So we dug into Jon's stash of barnacle recruitment plates from 2003 (complete with 8 year old barnacle tests) to find tags she can use.

Some scraping with screwdrivers and a few good rinses gave us slightly over 200 tags, all ready to be Z-sparred* onto Hexaplex shells.

Leslie is using plastic calipers for her measurements of Hexaplex, but the starfish I will be studying are a little too big for that. The bigger ones, Pentaceraster and Mithroidia, can have arms up to 17cm long. So I made my own measuring instruments out of an old transect tape, cable ties and old fishing weights. I have no idea what the weights were used for before (we pulled them out of an old box and they were all cable-tied together in fives) and I'm pretty sure that transect tape was hopelessly tangled long before I even knew what an echinoderm** was, but the cable ties were the only new component of my brand new starfish measuring tapes.

And while I had the fishing weights and cable ties on hand, I made a little upgrade to the underwater housing for my camera. The housing is positively buoyant (=it is floaty) when I dive, which is really annoying because it floats up and smacks me in the face when I'm not holding on to it. Canon makes a weight system for the housing, but it costs a whopping $26 for what is essentially a screw and a few pieces of metal. So I cable-tied a fishing weight to the bottom of the housing instead. We'll see how well that works tomorrow, when we do our first Galapagos dive (!!!)


* Z-spar is the name of an underwater epoxy. I think it is probably counted among the holy trinity of field marine ecology: PVC, cable ties and Z-spar.
** Echinoderm means "spiny-skinned" and refers to the group of animals that includes starfish (my study organisms), sea urchins and sea cucumbers.

Down to business

The general theme of our lab's research this summer is to elucidate the trophic (=feeding) structure of organisms that live in subtidal habitat in the Galapagos islands. For example, my project aims to figure out what the different starfish species are eating, and what is eating them, in order to establish their role in the food web. One of the ways we are doing this is using these little extreme-sports wearable cameras (with waterproof housings) to record video of starfish (or other study species) that are tethered within the camera's field of view. We can then analyse the video data to determine rates of predation on the starfish (or urchins, or whatever we're tethering) as well as what ate it. The GoPro cameras with extended battery packs are supposed to give us about 4 hours of continuous data.

The past couple of days has just been assembling these camera systems (and the stands) and testing them out to see how well they work, how much area/distance the cameras cover, etc. We've been snorkelling out around the dock in front of the marine research building of the Charles Darwin Station in Puerto Ayora. Here is a picture of a camera housing on its stand, weighted down by rocks. We were checking for stability and the watertight-ness of the housing on this round.

And this is me with the camera setup. I think I was sticking rocks on the base...or something. (Photos by Leslie)
On the way back from deploying the cameras, we ran into an marine iguana nomming on some Ulva (a green, sheety seaweed). I think I am starting to get used to the iguanas (hard not to when you're just about tripping over them every time you get out of the water...) but I still think they are the coolest things ever.

First look at the Galapagos

We took an early flight from Quito to Baltra airport in the central Galapagos islands on Thursday morning. If Quito by night is amazing, Quito from the air is just spectacular.


We got into Baltra airport and crossed over the canal to Santa Cruz island in a little ferry. From there it was a long drive into the town of Puerto Ayora, plenty of time to just check out the landscape. I have been on many islands, but this was like nothing I have ever seen. Capt. George Vancouver who visited the islands in 1795 described them as the most dreary barren and desolate country he ever beheld. There really aren't many tall things away from the high areas of the island, but it has its own beauty. Here are a couple of wide angle pictures from the GoPro cameras.


Towards the town of Puerto Ayora, there is more plant growth in general. And the dock area has a great intertidal zone!

Quito by night...

...is absolutely amazing. That is all.

Hello Quito

Jon, Leslie and I got into Quito late last night and pretty much passed out immediately. Our flight to Baltra in the Galapagos isn't till tomorrow morning, so we have today to check out the city. This was my first look at Quito in the light, from a 4th storey hotel room with a broken window.


Leslie and I spent the morning wandering around Quito. I attempted to try out Jon's GoPro cameras out of the water, before we switch out the wide angle lens for the flat one. I didn't realise I'd left the camera on time lapse instead of just single shot mode, so I ended up with 160 pictures that were mostly of the inside of my pocket. But here is one of the few decent shots I did get.


I never manged to get the haircut I wanted in the US because I was busy with packing, moving, taking the GRE and (of course) collecting and sorting algae. So we went looking for a place to get it cut in Quito. Here I am with my six dollar haircut and the milo tin I found at the giant hypermarket, Megamaxi. I am always excited when I see milo being sold (e.g. in Moorea, New Zealand) because it's so much harder to get in the US.

The W's of a species invasion

When people go beyond the typical "oh you are studying marine biology that really cool" talk (something that I should write about at some point) and want to know exactly what I am doing with my summers, I usually say that I am studying a species of seaweed that is not where it's supposed to be. Most people have never heard of the concept of introduced or invasive species before, so the conversation usually turns in that direction and only occasionally goes back to my research.

But these conversations makes me wonder how I can talk about what I do in a bit more depth, while keeping it interesting enough for people who think algae is sushi and muck on fish tanks. I am going back to a primary school English composition framework because I realised that studying a new species invasion is a bit like the compositions we were taught to write as seven year olds - you have to address the same spread of questions. Also, if you can explain your science to a seven year old then you either have a brilliant seven year old or you have achieved relatively good communication of your science. (Which is why you probably have to test it out on more than one seven year old.)

So here is a brief summary of the questions we are asking, in terms of the good old 5 W's:

1. Who

Who is the invasive? - This question is a little bit out of order, since we had to figure out what the algal species was in order to determine that it was a new invasive species. This question was answered last summer, thanks to Craig Schneider at Trinity College who first documented the presence of Heterosiphonia japonica in southern New England.

Mr. Hetsiph makes friends with a kelp stipe.

2. Where

Where is it now? - We have some idea of this from last summer and a tentative northern range limit, and there are people further south who are looking out for its spread.

Where did it come from? - Most likely from European waters, where it is also invasive, but possibly from its native region in the North Pacific. This could probably be figured out using genetic comparisons of the New England populations with potential source populations from different places, but that is out of this lab's area of expertise so it is probably a question for someone else to answer.

3. When

When did it get here? - Still unknown, but certainly sometime before summer 2009, when it was first found and identified in New England. We don't know if it was introduced only once and just spread rapidly, or if it was introduced multiple times in multiple locations.

4. What

What is it doing here? - This is where we're at now. What kind of interactions does our invasive species have with the native community of algae (competition for space and nutrients, maybe?) and the herbivores like snails and amphipods? To try and answer some of these questions, we are conducting field surveys of algal species and abundances, which will lead into field and lab experiments later on.

"What does this mean for me?"

5. Why

Why does this matter? - Probably the most important question of all. Why should anyone care? Well, invasive algae have been an issue in the western Atlantic for some time and some have significant negative impacts (e.g. Codium fragile). Coastal management agencies are interested in knowing the potential impacts of the invasion on coastal health, water quality, etc. And because of the relatively early stage of this species invasion, what we learn about Heterosiphonia could contribute to a more general understanding of what makes an invasive species successful, and how invasions spread.

That's it for now, tomorrow I shift gears completely and head for somewhere a little more exotic. I fly from Boston to Quito, Ecuador, and then take a domestic flight into Baltra in the central Galapagos archipelago on Thursday. Hopefully there will be more blogging from the land of the tortoises.

So what exactly am I doing with all this algae?

This is what I have been doing for the past week.

We've gone diving at sites in Nahant and in Rye, NH and put down 0.5m x 0.5m PVC quadrats like the one below. First, we visually identify each species of algae and record the approximate percentage of the quadrat that it takes up. Then we collect all the algae in the in the quadrat, put it in a bag and take it back to the lab. We collect about 10 bags per site.

This is a quadrat (pre-collection) from Nahant last year. I haven't yet taken my camera underwater this summer.

In the lab, we sort the algae by species and clean it - i.e. remove little critters like amphipods, isopods, little crabs, little starfish*. The result is something like in the picture - neat piles of algae on a lab tray. Then we weigh the algae by species in two ways: 'fresh weight' which is just spinning it down in a salad spinner to remove excess water and then putting it on a scale; and 'dry weight' which is putting it in an oven at about 65ºC so that it is completely dried out, and then weighing it (this destroys the algae so you can't do anything with it after).

This is all the algae from one (0.5 m x 0.5 m) quadrat from our Rye, NH collection site. I am pretty sure that if I cleaned up the algae up a bit better and arranged everything a bit more prettily, I could convince someone that it is some kind of Japanese delicacy that they should try.

This whole long process gives us estimates of two things:
1. How many species of algae are out there, and what they are
2. How much of each species is out there, in absolute terms and relative to the others. This can be measured by percentage cover of the quadrat or by weight. We are doing both to see how well the two agree (i.e. if one is an accurate proxy for the other).

These two things can then be used to tell us plenty of other things such as how diverse the algal community is, and which species we should use in lab experiments.


*This is described in one sentence, but is the longest, most tedious part of the whole process. It took us <1 hour of underwater time to collect 10 bags of algae, and a full day to clean, sort and weigh only 7 of those bags. During the process I wrote this song.

The Algae Song
(to the tune of "Daisy Bell")
Algae, Algae, give me your answers true
I've gone crazy, just from sorting you
The amphipods are too many
And Desmarestia is nasty
But soon I'll find
If Hetsiph might
Influence diversity

Return to Cunner Ledge!

I've been working hard on collecting and sorting algae from morning to night for the past few days, but this morning I found some free time to walk around Nahant's East Point, which is always nice. It was just after low tide, so I went out to my old field site next to Cunner Ledge. Here it is, marked with the yellow arrow in the picture and on the Google map for East Point. You can also see the Marine Science Center on the map.


I am a little less sure-footed than I was last summer (especially since I was climbing the rocks in flip-flops this morning) but I went back down and looked for my 0.5 m x 0.5 m plots. We set up 30 plots along that seaweed-covered ledge last July. My plot markers are still around :)

This was the very first field experiment that was truly my own - Matt helped me set up the plots at the start, but I collected the data and maintained the plots for the 8 weeks that it ran. It was a small-scale manipulation of the diversity of basal species, i.e. species that bring energy into the system. Seaweeds do this through photosynthesis and filter feeders like barnacles and mussels do this by consuming plankton from the ocean.

And while we're on the topic of my field site, I finally got round to digging up the screencap of Cunner Ledge in the movie Shutter Island. The movie was partly filmed in Nahant, and my field site makes a half-submerged appearance. So here we have Leonardo DiCaprio pointing a gun at a guard, which is all very interesting, but LOOK THERE IS MY SITE IN THE BACKGROUND. Which is really the best part of the entire movie.

Off site algae collection

Today we drove slightly over an hour north to Rye, NH to revisit a site from last summer and do some algae collections there. This is a picture of our entry point into the water, and the actual site of collection is just next to/behind the big rock on the left.

The picture is deceptively warm and sunny and hides the fact that the water temperature was still 7ºC/45ºF, which is about where it is in the early winter. So we were freezing in our wetsuits for both dives and I am still cold 7 hours after exiting the water.


But on the way back we got crabcakes at a roadside place and sat in the sun and it seemed like New England summer again.

The great escape

Living and working in a marine lab is always interesting because things like this happen.

I am sitting in the lobby of the building at night, working on my laptop. Out of the corner of my eye, I catch movement in the dark, empty main lab. An escaped green crab scuttles out into the lobby in a small burst of speed, then pauses to see if anyone has noticed.