Friday, July 26, 2013

Scoping Out Larval Diversity in Bocas del Toro

Does spending two weeks in a tropical paradise in the lab with your eyes glued to the microscope sound like fun to you?

Two weeks looking through the microscope - exactly what the participants of the "Larval Invertebrates: Diversity, Form and Function" workshop did in July.  In fact students and instructors came from around the world for this chance to develop eye-strain and miss out on getting a tan.  

Well, it does to larval biologists - scientists who study the beautiful and diverse developmental stages of marine invertebrates and fishes.  In July we held a workshop at STRI's Bocas del Toro Research Station, focused on the diversity of invertebrate larval forms. Here's a little bit about what we did.

We started the day with a short (30 minutes, or maybe an hour) trip to the field to collect samples, using plankton tows.  Nets with a tiny mesh size of 0.125 mm catch the larvae and many other small organisms.  We let the boat drift slowly while we tow to stop the delicate organisms getting mashed against the sides of the net.  
Marco carrying samples up to the

The group setting off from the dock.

Bringing the net into the boat.

After the short field trip, we spent 6-8 hours looking through the microscope picking through all of the other planktonic organisms -- various microalgae, like diatoms and dinoflagellates, as well as gelatinous zooplankton like jellyfish and ctenophores -- to find the precious larvae.  The plankton in Bocas is so rich that 15 people can spend 6 hours each just to sort through the contents of 2 buckets.  It sounds tedious but it's like a treasure hunt -- you don't want to stop looking just in case something really exciting is in the next slurp of plankton.

Like caterpillars and butterflies, the larval stages of marine invertebrates usually look nothing like the adults.   In this case, however, the larvae are beautiful. Lovely. Delicate. They often turn into fairly mundane adults when they grow up. Usually worms you wouldn't look at twice, which give no hint of their ethereal appearance earlier in life.

Some of the larvae collected in Bocas del Toro.  Photos by Karen Chang and Michael Boyle.

For years, before scientists could match the larvae with the adult animals, the larval forms were given their own names.  Now we know that actinotrochs (top center) are larvae of phoronid worms, or mitraria (not shown) are larvae of owiniid worms (it all sounds like Greek - or Latin- doesn't it?).  The morphology can tell us it's a phoronid or a owiniid, but not what species or even what genus it belongs to.

We are trying to use DNA barcoding to match the larvae to the adults.  In collaboration with the LAB in the Natural History Museum, we will sequence the COI gene from 100s of larvae that the workshop participants picked from the plankton and photo-documented.  The results, when we get them later in the year, will be compared with published COI DNA sequences from adult animals.  This will tell us if larvae that look the same all actually belong to the same species.  For some groups we will be able to match larvae to adults for the first time, documenting the kind of development for many of these poorly studied tropical species.  Most exciting of all, we expect to find species where the adults have not yet been discovered or reported in Panama.  

To learn more about invertebrate larvae check out the fantastic blog from Svetlana Maslakova's lab at the Oregon Institute of Marine Biology.

Wednesday, July 24, 2013

Early Morning Fight to Bocas del Toro

Today I’m on the Caribbean coast of Panama, at the Bocas del Toro Research Station.  As scientific director of the station I make frequent trips across the country from my base in the Naos Laboratories in Panama City.

The 6am departure makes
for a long day.
It is best to arrive before the rush.

The Monday morning flight is popular and there are often several STRI visitors or employees on the fight.  10 years ago when I first started to travel to Bocas you could arrive 15 minutes before the flight and you could get a coffee for 50 cents.  Now the airport is often packed and it’s hard to believe that the fancy coffee shops charge $4 for a small “large”.

Fort Amador on a hazy morning.
Islas Naos, Perico and Flamenco. 
For more about the Causeway and
The 50-minute flight passes directly over the Causeway and the Naos Labs, then crosses the country parallel to the Panama Canal (the flattest part of the country).  Sometimes the flight path takes you over the Canal.  

Coming into Bocas... 

An early morning, hazy view of mangrove islands 
around the large island of Solatre.

......offers a great view of the complex topography of the region.  Several large islands surrounded by numerous small cays are all fringed with mangroves. If you look closely you can see that the mangroves are taller around the edges of the small keys. You can’t tell from the air, but the trees in the center of these islands are dwarfs, reaching heights of only 3-4 feet.  Research at the Bocas Research Station has shown that this pattern is due to nutrient limitation.  Seawater brings nutrients to the outer trees but as the water penetrates the dense mass of roots the nutrients are rapidly depleted.  If you fertilize the trees on the inside they shoot up and begin to look like the outer trees. 

One of the Zapatilla Cays is the site of a long-term project on the biology and
conservation of hawksbill turtles.  The view from the plane is nicer on sunny days.

A very quiet early morning on a wet day.  You can hardly 
imagine this sleepy main street full of tourists.
The town of Bocas del Toro is a different world from Panama City.  Sleepy and, at the same time, a touristic hotspot, full of restaurants and bars.  I bypass what’s on offer and head in to work.

Arriving at the station before 8, I have a few minutes before the staff arrive and the researchers appear, ready for another day in the field or lab.

The BRS station building.  Peaceful in the early morning.
It's going to be a busy day.  Welcoming the students and instructors of a visiting course.  Meeting with my advisees, and discussing budget and administrative issues with the station staff.  If I’m lucky I’ll have time for a swim.  If... I finish before dark.... and it doesn't rain too hard....