Post #5

Conducting fertilization experiments with Acanthaster is replete with challenges, rewards and sometimes real pain.

Yesterday I ran my first trial run of the experiment.  I started shortly after 7 a.m. and finished cleaning up the test tubes and beakers around 9:30 p.m.  There was a lot of prep work.  We had to determine the sex of all the COT we had collected by cutting into them as I showed you in previous posts.  We then placed the males and females in separate blue tanks to minimize the chance that sensing the presence of the opposite sex would stimulate spawning.  We also had to make up various solutions, label tubes, gather pipettes, etc.  So the actual experiment didn't start until the afternoon.  Here's what my lab space looks like, pretty crowded but that is typical here:

The blue rack of tubes to the right of the dissecting microscope is holding the COT eggs and sperm.  The experimental design involves putting about the same number of eggs in each tube (400-500) but making a serial dilution of sperm.  If things go as planned, some tubes will have too many sperm causing more than one sperm to fertilize an egg ("polyspermy") resulting in abnormal development, and some tubes having too few sperm resulting in some eggs not getting fertilized.   After the eggs and sperm were mixed, the tubes were floated in one of Emily's coral buckets (the subject of a future blog) that had flowing sea water at ambient temperature (28.1 degrees C or 82.6 degrees F).  I collected the tubes after about 3 hours and counted how many of the eggs were developing normally, how many were abnormal, how many were not fertilized, etc.    This is what some of them looked like:

The eggs and embryos are put on a raster slide that has a grid on it to facilitate counting.  The brown spheres are unfertilized eggs and the groups of cells contained within a fertilization membrane are developing embryos.  The cells look pretty disorganized and not as neatly arranged as they are in the early embryos of most other organisms, but this is typical of star fish.

Yesterday's experiment clearly showed that this experimental protocol can work with the COT.  However, progress has slowed today because of one of the challenges of working with Acanthaster, whose name literally means "spiny star."  I've been stabbed several times collecting these guys.  The initial stick feels like a needle prick, with more pain from the toxins increasing over the next several days. The wounds from January 18 are just about healed, with what feels like a lump of scar tissue under the skin.

Two days ago we went back to the spot on the NW corner of the island and collected 7 more COT, some of them huge (~2 feet across).  With the surge from the waves coming over the reef, we were getting knocked around and it was hard maneuvering the stars into our catch bag.   Even though I was trying to be careful and wearing gloves,  I got stabbed a couple more times.  Neither stab seemed that bad at the time, but as luck would have it, the one in my left index finger has become increasingly inflamed.  Here is a picture I just took of it:

(There's a COT in the background in its tub for context.) The skin is taut and the last two digits are so swollen that I can't bend the joint.  Redness is progressing towards the base of the finger. (I'm typing this without the use of that finger, which is really slowing things down!)   I don't see clear evidence of infection, I just think the redness and swelling are due to the toxins.  However, if things aren't better in the morning I'll see if I can find a doctor,  assuming doctors here have experience with COT wounds!

So even though my finger throbs, a good anesthetic is just looking around at the scenery:

Post #4

Some Acanthaster success at last!

I went snorkeling two days ago to a new spot on the northwest corner of the island.  I was eager to check out that part of the fringing reef because researchers returning from there said they saw a lot more live coral there than out front of the lab.  Plus, one snorkeler had counted 19 COT (crown of thorns star fish) in about 1 1/2 hours.  It was a rough day to go, for the weather had changed from day-after-day of calm seas and blue skies to a dark gray cloud cover and higher winds.  The winds caused big swells to develop that crashed on the reef, causing surges and currents in the shallow back reef area where we were snorkeling.  Still, I found 5 COT and brought back the biggest two of them.  Lucky for me, one was a male and the other a female.

The COT are placed in large blue mesocosms (tubs) with running sea water.  When ready to use, I carefully remove a COT while wearing protective gloves.  (The spines still can go right through these gloves and their wounds really hurt for days.) (Yes, my left hand does have a glove on it.)

For a dissecting tray, I use a clean garbage can lid.  One must be resourceful when in remote field stations......

This one had already been operated on.  You can see the white spots that are the stumps of the spines that I cut off to minimize the chance of getting punctured!  Since I need eggs and sperm in order to do my fertilization experiment, I dissect out a few gonads from near the "armpit."  In the COT, there are separate males and females, and the gonads can be found in this armpit region of each arm.  In the ocean these animals "free spawn," releasing their eggs and sperm into the water where fertilization takes place.  I need to have fertilization take place in a test tube, so I remove some of the gonads from "ripe" individuals.

Starfish have an amazing ability to recover from injury and regenerate lost limbs.  The COT, like some other starfish, has been reported to completely regenerate from just one arm (as long as it has part of the central disk area).  Thus I'm assuming these COT will recover after I return them to the reef.

So what to starfish gonads look like?  Take a look:

The orangish frilly organ in the upper right of the cut is digestive gland, the white stuff on the left side of the cut is mostly gonads.   There are many gonads in each arm of the COT.  I remove some gonads and put them in a dish of sea water.

Food storage containers have all kinds of uses!

In the lab, I treat the ovaries with a chemical (10-4 M 1-methyladenine, for those interested) to release the eggs, then add sperm from testes cut up in a bit of sea water.  Put these some eggs and sperm on a microscope slide and Voila!  (this is French Polynesia, after all....) Fertilization!

These eggs are about 0.2 mm in diameter.  The one on the right did not get fertilized while the other two are surrounded by a fertilization membrane, which lifts off the egg after a sperm enters.  Seeing this really excited me, for it means that I now can run all the preliminary experiments needed to fine tune the protocol for my "big" experiments.  I hope seeing starfish eggs excites you too!

(All pictures but the last one were taken by Emily.  The last picture I took through the microscope using an attachment enabling me to mount my SLR on the ocular tube.  Pretty handy!)

Post #3

The coral my daughter Emily works on is found in shallow water.  It can easily be collected by snorkeling, or in many locations by wading out from shore.  Below are Emily and Chelsea, an undergraduate research student from the University of Hawaii, wading out from a beach along the northwest side of Moorea late in the afternoon several days ago.  This was the second trip to this spot within the past week.

Just to the right of this picture is a rock about 20 meters off shore that just barely sticks up out of the water.  On both days there was a group of about 8 children, perhaps 3-10 years old,  frolicking on and around the rock.  This was clearly their playground, their sandlot, the way they spent their afternoons.  Imagine being a child and being able to play for hours on end in the ocean, day after day, jumping, swimming, splashing, exploring.  Lucky them!

This is some of what their playground offered:

Sea cucumbers with their frilly oral arms sweeping up food-rich sand to process, and

forests of stag horn coral filled with territorial damselfish, crabs, snails and other critters.

Well, of course the children were curious about what Emily and Chelsea were doing, so....

pretty soon the entire group worked their way over to investigate.

Interestingly, several said they had been told not to collect coral, which is encouraging.  We tried, with our limited command of French, to explain that we were conducting research on coral that would hopefully help save them.  They very quickly learned which species we were interested in, and eagerly wanted to help...

though we couldn't seem to explain that corals removed from the water were of no use to us.

What delightful children, friendly, fun to have around....

Post #2

One of our first priorities was to deploy a SeaFET, a newly designed underwater instrument programmed to measure the sea water’s pH every 10 minutes.  Along with the SeaFET we attached a tidal height recorder and a temperature recorder.  These data loggers help provide researchers with a better picture of the dynamic environment to which organisms are exposed.  Here is a happy Emily with the equipment hose-clamped to a sunken cement piling.  We will recover these in March before we leave and download the stored information.

A second priority was to collect Acanthaster planci, the crown-of-thorns sea star.  This sea star feeds on corals and periodically (about every 20 years or so) experiences huge population explosions where they can become so numerous that they literally can eat almost all the available corals in an infected area.  The reef out front of the labs here suffered such a population explosion in  ~2007, and now instead of having about 60% live coral cover has less than 10%, so it looks pretty dead at the moment.  It reminds me of the seemingly dead areas after forest fires, and like new seedlings growing in burned areas, the seemingly barren reef areas out front are loaded with tiny coral “recruits” less than 3 cm across.   Thus the cyclical “destruction” and regrowth of the coral community continues.  This has been going on for decades, if not centuries.  Interestingly, the local Polynesians see this periodic rebirth of the coral reef as a good thing, and even have a traditional song about it.

However, this means that with little live coral around, the crown-of-thorns is pretty rare right now here.  I have found no more than 2 in any given scuba dive or snorkel.  Here is a picture of one I found on my second dive.

Unfortunately, every one so far has not had ripe gonads.  (I need to get their eggs and sperm for my experiments.)  At first I determined that they were not “sexy” by dissecting them back at the labs by simply making a cut in the “armpit” area where the gonads are.  This should not kill them for they are good at regenerating.  Now I take my dissecting scissors into the water with me and open them up in situ.  Here is a male after being opened up.  The orange-brown organ is digestive gland.  The testes in this animal were tiny and not easily discerned here.  Bummer!

Perhaps the sea stars do not have large gonads because they are starving now that there is very little for them to eat.  Thus tomorrow we hope to snorkel on the west side of the island where the live coral cover is reported to be much higher.  Wish us luck!

Post #1

This spring I am on sabbatical leave from SUNY Cortland where I have been teaching in the Department of Biological Sciences for many years.  At Cortland I have been lucky enough to teach classes in invertebrate zoology and marine biology, among others.  Although my formal training has involved studying primarily temperate marine invertebrates, I take my marine biology classes during the January intersession to wonderful sites in Belize in Central America operated by International Zoological Expeditions.

This January-March I am working at UC Berkeley’s Richard B. Gump South Pacific Research Station on the island of Moorea, which is just west of Tahiti in French Polynesia.  My research is in collaboration with Dr. Gretchen Hofmann, a professor at UC Santa Barbara well known for her work on sea urchin development and more recently for running a lab group consisting of graduate students and post-docs focusing on the effects of ocean acidification (OA) on the physiology of and early life history stages of marine invertebrates. 

So what does Moorea look like?  Take a look:

This is looking east with Tahiti in the background.  The Gump Station is in Cook's Inlet which goes in from the second large indentation in the fringing reef 7/8 of the way back on the left side of the island.

There were basically two reasons why I was drawn to the Gump Station this spring: one is the opportunity to do some interesting research in the tropical South Pacific, and second is the opportunity to work with my daughter Emily, who is a graduate student of Dr. Hofmann’s.  Emily is investigating the effects of OA and increased temperature on the larvae of the coral Pocillopora damicornis, a common branching coral of the IndoPacific.   My research goal for this trip is to investigate the effect that OA might have on fertilization success in the crown-of-thorns sea star Acanthaster planci.

We spent more than a week at UC Santa Barbara getting ready for this trip by packing carefully (there are very few resources here at Gump, so we needed to bring everything from the chemicals we needed to slides and cover slips) and practicing some the experimental protocols and water chemistry I would be doing here.  We arrived  in Tahiti late on  January 17 and had to spend the night there before taking an early morning ferry to Moorea.

That first day at Gump involved a lot of getting oriented, unpacking and organizing the lab space we are to occupy for the next two months.   There are maybe 20 other professors, post-docs, grad students, undergraduates and technicians energetically conducting research here, so the place is a beehive of activity.   At any time, there are folks heading out or coming back in one of the numerous outboard boats from their snorkeling or scuba research dives.