Monday, October 19, 2015

Social behavior of green turtles in Western Australia

 Dr. Jordan Thomson

Since 2011 we’ve been using animal-borne video cameras to study the behavior of sea turtles in Shark Bay, Western Australia. Since sea turtles can be hard to observe in the wild for meaningful lengths of time without disrupting their natural behavior, very little is known about how they interact with one another (aside from courtship and mating, when they’re relatively stationary and, well, otherwise occupied). Animal-borne video cameras overcome this challenge by remotely recording the first-hand perspective of a turtle for several hours as it moves freely throughout its habitat and interacts with other turtles. The resulting footage is a treasure trove of insight into their secretive social lives!  To see some of the footage visit the lab YouTube channel.

In 300 hours of video footage recorded from the backs of 93 green turtles, we recorded about one turtle encounter per hour of video – a fairly high encounter rate considering the generally solitary nature of most adult sea turtles. We recorded a huge variety of interactions that ranged from brief one-on-one encounters lasting just a few seconds to behaviorally diverse encounters lasting up to 20 minutes and involving up to seven other turtles.

The main finding of our study was that the nature of turtle encounters depended on what type of habitat it occurred in. Shark Bay is a large (13,000 km2) bay with expansive seagrass meadows, which turtles use for feeding. Hard-bottomed, vertically structured habitats like rock ledges and coral heads are relatively rare and occur mostly in the deeper areas of the bay. Despite their limited availability, structured habitats are really valuable to sea turtles because they use them for a variety of critical non-feeding activities like resting or seeking refuge from predators (Video 1), rubbing their bodies on hard surfaces to “self-clean” by removing epiphytes like algae and parasites (Video 2) or posing to allow fish, like the black and gold fish in the background in this video (Video 3), to clean them in a “mutualistic” interaction where both species benefit (fish get food, turtle gets cleaned to reduce drag while swimming).

Since hard-bottomed habitats are so rare in Shark Bay, and feeding sites (i.e., seagrass beds) are so plentiful, we hypothesized that we might see competition for access to resting/refuge/cleaning sites while we shouldn’t see competition for access to feeding sites. And this is in fact what the video showed. Turtle encounters over seagrass beds tended to be brief, innocuous and typically involved just one other turtle (Video 4). In contrast, turtle encounters in hard-bottomed habitats were much more frequent (Video 5), despite the fact that turtles spent only 5% of their time in these areas, often involved several individuals, and regularly involved physical contests between turtles for access to these spaces (Video 6). This competition could be important to individuals and populations, since less competitive turtles would be displaced from the best resting/refuge/cleaning sites and could experience higher levels of predation or have to spend more energy while swimming (due to drag) as a result.

For more information on this study, check out the article in Marine Ecology Progress Series ( or email me for further information (

p.s. if you’ve ever wondered what a Western Australian sunset looks like from the perspective of a sea turtle (haven’t we all?), wonder no more (See the video).

Friday, February 13, 2015

Sea turtles of Abaco, Bahamas

PhD Student Elizabeth Whitman has been working on green turtles of Abaco Bahamas since last summer.   As part of her research she put up large cages (exclosures) that keep turtles from grazing on the seagrass.  By placing exclosures in different areas she hopes to figure out how important turtles are in structuring seagrass beds and whether their importance varies in space and time.  Below is a summary of her brief field trip in November, 2014 to check on her experiment.  Check back later this spring to read about her upcoming work to deploy cameras on turtles on several islands in the Caribbean!


This past November I revisited my study sites on Abaco to collect data and check on the condition of the exclosure cages.
Linda Gardner performing seagrass shoot counts in one of the full exclosure cages.
At each of the exclosure study sites (Bight of Old Robinson creeks, Snake Creek, and Hill’s Creek) we first visited each plot and marked 10 seagrass shoots that we would collect one week later to measure growth. I was pleasantly surprised at the good condition of the exclosures (they have been out for months now), so over the course of our trip we only needed to perform minor repairs and cleaning. We also surveyed the seagrass and algae, measured seagrass canopy height, and counted shoot density within each plot . 
The location of seagrass shoots marked for growth measurements are marked by the white flag; seagrass and algae surveys were conducted within 50 x 50 cm quadrats at four locations within each plot

Visually, the seagrass appears to be benefiting from the protection from grazing at Hill’s Creek, but I am still working on the analyses and it might take more time to see a big effect if there is one. With the help of local volunteers who will be visiting the cages during my absence, this experiment will run through the summer of 2015 when I will be back for my next round of data collection. By keeping the exclosures in place for one full year, the I will get a more accurate picture of green turtle grazing behavior and the effects of green turtle grazing on the seagrass in the creeks of Abaco.
Back at the lab at Florida International University I am busy, along with a few undergraduate volunteers, prepping the seagrass we collected for nutrient analysis. I am also actively working to secure support for my summer research trip and to expand upon the sea turtle field course and tagging program with Friends of the Environment.

An exclsure cage viewed from above the water.

A small nurse shark resting in the seagrass.

Sunday, November 16, 2014

Guadeloupe Sperm Whale Mission: Day 7

Saturday, November 15th

Well, I am now back home and Kirk has taken over.  We came close today.  We were out the door before 6 and on glassy calm waters.  Unfortunately, they didn’t stay that way!  We had traveled along almost the entire west coast of the island and were about to turn back when a whale watching boat called to tell us they had sperm whales.  We blasted through the growing seas but by the time we got near the GPS position the whales had been at they were already miles away and heading in a direction that would make it impossible to put the camera out and have any chance of getting it back when it came off.  It was tough to let the opportunity go, but the team has plenty of time left in the mission so playing it safe was the right call.

The day was far from a loss, though.  We encountered two groups of pilot whales – each with 30-40 individuals, snoozing at the surface.  We got plenty of pictures to see if they are the same whales we encountered earlier in the week.  Eventually we had to head back to shore so I wouldn’t miss my flight (which it turns out wouldn’t have happened since the computers were down at the airport and everybody had to be checked in by phone…no surprise that came with a delay).  On the way, we ran into a group of common bottlenose dolphins.  They were the offshore variety (not a separate species though) so they were big!  We got our pictures, the dolphins rode the bow, and we headed back to shore.

Common bottlenose dolphins riding the bow of the research boat.
Although we didn’t get as many cameras out on sperm whales during my time, it was a successful mission!  It was great to get to know all of our collaborators at SPAW-RAC and to see the potential for studies of so many species and the real capabilities of Mehdi’s cameras.  The jury is still out on his lucky shirt after today, though.

I’m told the best season for the whales is in the spring…when our next mission will go!

I will keep updating the blog – though not daily – as the team sends in reports, photos, and videos!

Friday, November 14, 2014

Guadeloupe Sperm Whale Mission: A day of rough toothed dolphins

Friday, November 14th

Well, if you spend enough days on (or under) the ocean, you are pretty much guaranteed to see something really bizarre.  Today was one of those days.  On the list of things I thought I would see today, I never would have put a brown bat flying four miles offshore, skimming over the waves and sometimes coming wing to fin with flying fish way down on the list!  But, that is what we saw at about 830 this morning, in full daylight.  The confused bat swung by the boat and then kept heading out to sea.

Unfortunately, bats were more common today than sperm whales.  After seeing at least 20 individuals spread between multiple groups yesterday, I liked our chances.  And the cameras were optimized and ready to go! Maybe we need to get Mehdi to wear his lucky shirt again tomorrow.

On the good side, we had a couple of amazing encounters with rough-toothed dolphins.  It was a new species for me!  There were between 30-50 individuals in each group we saw and they were a lot of fun to watch.  I had always wanted to see rough-toothed dolphins because they tend to be found in smaller groups than a lot of the offshore dolphins and are reported to be very social.  Today’s encounter did not disappoint.  Almost all of the dolphins spent time in very close proximity to at least one other individual, their pectoral fins often touching.  Pairs, trios, or even groups of six made perfectly synchronous surfacings and some dolphins “pet” each other with their pectoral fins…a

Rough toothed dolphins
dolphin massage!  A lot of the behaviors looked very much like what I saw when I studied Indo-Pacific bottlenose dolphins in Shark Bay, Australia.  The encounters didn’t last that long because we were looking for sperm whales, but they were memorable.  They brought the total species count for the week to at least five (it could be six but the possible beaked whale sighting a couple days ago was too fleeting to be sure it wasn’t a white cap as the wind blew up).

Tomorrow is my last day on Guadeloupe and I am hoping that I can get a camera out there before I run to my flight.  If I don’t Jeremy, Mehdi, and the SPAW-RAC team carry on for more than a week and Kirk Gastrich is coming down from FIU to take my place!

Before I sign off – to answer one question from the blog yesterday…How do we put a camera on a sperm whale?

The camera is attached to a suction cup that will hold onto the whale for hours or days.  But, the cup has a dissolving link and a computerized release so it will come off when we want it to.  For our first deployment it will be a few hours to make sure it is all going well.   The camera is mounted on the end of a long pole.

Once we find whales, I hold the pole on the front of the boat, while the driver slowly maneuvers us next to the whale without startling it.  Then, I reach out and gently press the cup onto the whale and the camera falls off the pole.  Sounds easy.  It really isn’t J 

Thursday, November 13, 2014

Sperm Whales of Guadeloupe: First Days

The lab is just starting a collaborative project with SPAW-RAC to investigate the behavior and ecology of sea turtles, sharks, and marine mammals in the French Caribbean.  The project, funded by Total Foundation (France), has a goal of advancing science-based conservation of these taxa.  We will be working with many excellent partners and scientists and plan to develop new animal-borne camera technology (or rather Mehdi Bakhtiari of Exeye LLC will) and a high-quality education program (with Symbio Studios’ Patrick Greene)!  We are embarking on our first marine mammal mission – to collect biopsy samples from, and deploy cameras on, sperm whales off Guadeloupe!

We will be updating our websites to give all the background of the project and provide results (and hopefully some really great video) as soon as we can.  For now…here is the story from the field!

I hope you enjoy!


PS It does get more exciting toward the end…I promise

Saturday November 7th

Stream by our cabin
We arrived on Saturday and drove about an hour through the rain from the airport at Pointe-a-Pitre to our mountainside accommodations along the west coast of the island where we will be searching for sperm whales!  

With all the gear that Patrick, Mehdi, and I had brought we were very lucky that lab postdoc and mission leader Jeremy Kiszka had two cars waiting!  Neither of the cars was terribly happy about the uphill climbs or the rough roads with all the weight!

We quickly got to work settling into our open-air accommodations and we started setting up the camera gear and whale-cams … all to an impressive chorus of frogs...yes loud enough to keep you up at night!  

Mehdi's workshop
It is amazing how far we have come with animal-borne camera technology in the last decade...Mehdi has designed amazing units that are smaller, record longer, can dive deeper, and feature much better video quality than the systems we were using not that long ago! Thanks to the smaller and lighter units we also have a longer and lighter pole, which should help us get many more deployments!  The new, smaller, suction cups will also be a big help – without needing to actively suck the air out of a large cup we should be much more successful and eventually be working with species much smaller than sperm whales!

It is great to have such a fantastic team together! Jeremy and the SPAW-RAC team (who we are collaborating with on this project) are outstanding and Patrick and Mehdi are simply the best at what they do!  I can’t wait to get out on the water

Testing the deployment pole

 Sunday November 8th
We were up and on the road by 545 on Sunday and set out with our boat captain, Dany Moussa for a recon mission.  We can’t start tagging until tomorrow but we wanted to see if we could locate the sperm whales and planned to investigate a possible location to start working on sea turtles.  We also had a few things to check out with the cameras, including the critical floatation test (they passed, and quite well too). 

Conditions on the water were not great and we didn't find any sperm whales in the morning, but we did encounter a really nice group of short finned pilot whales.  Pilot whales can dive quite deep, although not as deep as sperm whales.  Some scientists have called them “cheetahs of the sea” because they dive down slowly then make a sprint during the final descent to catch their prey – which is usually squid!  Despite the conditions, we got a set of photos of the dorsal fins (that is how we can tell individuals apart) and even got a quick look underwater. The water here is quite amazing! It is crystal clear ... perfect for the work we are trying to do.

Jeremy photographs the pilot whales
We didn’t find any sperm whales so we headed in shore to snorkel the seagrass beds and coral reefs.  The reef was healthier than many I have seen around the region.  There was a lot of living coral, including soft corals, beautiful sponges, and tons of reef fish.  The nearby seagrass beds were a slightly different story.  Although there was a lot of seagrass, there was a decent amount of a species that is invading the island – and others nearby.  The green sea turtles in the area – and there were a lot of them (we must have seen more than a dozen in a short snorkel) – were happily eating it though.  One interesting thing about the turtles was the size of the remoras stuck to them!  I have never seen such large remoras on turtles…or seen huge remoras swimming around looking for a turtle to latch onto!  Compared to those remoras, our turtle cams are quite small!  That’s a good thing because the turtles seemed completely unconcerned about the remoras.

Green turtle with hitchhiking remora
Monday November 10th

Our first day for possibly deploying a camera came and went today.  We had two boats – our primary tagging boat and one with staff from SPAW-RAC and the national park.  Between the two boats we drove hundreds of kilometers and saw tons of…water!  And that was about it except for one set of surfacings by a group of at least three beaked whales.  We think that they might have been Gervais’ beaked whales, which are incredibly elusive and rarely seen.  Unfortunately, after searching for a while we couldn’t find them again.  Given that beaked whales can easily dive more than 1000m deep and hold their breath for a very long time (we actually don’t really know how long but some species stay down well over an hour), it isn’t surprising.  We also were trying to find sperm whales so that was our focus.

Dany, Mehdi, and Jeremy listen for sperm whale clicks
Working with deep-diving species isn’t easy.  Sperm whales can stay down more than an hour and dive to over 1500m (a mile) deep (yes, Mehdi’s cameras can handle it).  Even though they usually dive for sorter periods and not quite that deep it can make them hard to find.  The good news is that you can use sound to find sperm whales.  By listening to the clicks that the whales make when foraging (they use echolocation in the same way bats do to “see” and find food in the darkness of the ocean depths) or finding their way, you can tell if there are any whales within a few kilometers of the boat.  That’s why we stop every few miles to have a listen.  

At the end of the day, we heard sperm whales making clicks off in the distance.  Using a hydrophone that only hears sounds from a particular direction we were able to get closer to the whales – but we still didn’t see them.  Both boats worked hard to find the whales, but we lost their calls as the waves grew higher and we had to call it a day when it got too late to put a camera on one (for our first trial we don’t want the camera on for days).

 We’ll give it another try tomorrow! 

Tuesday, November 10th
Pan-tropical spotted dolphins.  Young individuals don't have spots.
Any hopes of this being an easy mission were starting to dissipate today.  Luckily, the whole team has three more weeks but Patrick has to leave Thursday and I am out Saturday evening the clock is ticking for us.  No sperm whales today, again.  We put in hundreds of kilometers and moved between waters 800-1500m deep – prime sperm whale habitat.  We did have a really fun encounter with several large groups of pan-tropical spotted dolphins.  There must have been more than 500 individuals between the groups.  One reason they are probably in such big groups is for protection from predators (like sharks).  There isn’t anywhere to hide in the open ocean so it is all about safety in numbers.

We took as many photos as we could for identifying individuals and enjoyed watching them ride the

bow of the boat, socialize with each other, and then bow ride some more.  The dolphins actually were with us for quite a while as we tried to look for sperm whales. We actually couldn’t use the hydrophone to listen for sperm whales because the dolphins were so loud clicking and whistling. 

We ended the day testing the VHF (radio) signal that the camera transmits when it floats to the surface.  The signal in these new cameras is very strong and without much trouble, we were able to find it after leaving it floating behind us.  The test made us confident we will be able to get the camera back once it releases from the whale at the programmed time and floats to the surface.  Of course, first we would need to see the whales.  And then get very close to them.

Mehdi predicts we will see sperm whales at 1030 on Thursday.

Wednesday, November 11th
Ugh.  Another day of very nice weather and no whales anywhere to be found.  We heard a distant sperm whale or two as soon as we got out on the water but never could find it.  There was a lot of boat traffic – including ships - in the area, which made it very hard to hear.  We drove a lot of miles and listened to a lot of ocean, but no whales.  Towards sunset we helped Patrick get a few nice scenic shots and had to call it a day.  We are going to miss having him on the boat and wish the whales had been around for him!  But, maybe tomorrow will be our lucky day.  Mehdi says he is wearing his lucky shirt and I (accidently) sacrificed one of my favorite pairs of sunglasses to the ocean.  One of those has to work…
This is what we are trying to find....

Thursday, November 12th

Unfortunately, Patrick had to leave today to go to a shoot in California.  We were sorry to see him go but headed out on the water with our two boats early…and maybe a little less packed with gear.  Admittedly, we were getting a little desperate so we headed south of Guadeloupe into an area with rough seas but steep slopes underwater that might be good spots for sperm whales (or any whale or dolphin for that matter)!  We check the hydrophone but no luck.  Mehdi’s 1030 guess and lucky shirt were not looking like they were going to come through.

So close
But then Dany got a phone call.  Another boat was with two sperm whales off the northern portion of the west coast!  We immediately started the 30 minute run to get there, hoping that we wouldn’t be too late and the whales would slip away from us again!  We soon got out of the choppy seas and were skimming across flat calm waters, raising our hopes that today would be the day!

Suction cup tag on whale
As we approached the boat that was waiting for us we could see spouts.  I think the whole crew was relieved and excited at the same time!  The whales dove just before we got to the other boat and after a quick chat, we started looking in earnest.  It was a long ten minutes before we saw it surface again and began to head towards it (this was at 10:12, so you be the judge if Mehdi was right).  Before we got too close, the whale dove again and we started trying to slowly drive to where we thought it would resurface.  As we scanned the horizon, we realized whales surrounded us!  There were individuals and small groups in almost every direction.  At 10:28 the whale resurfaced and we moved in, ready with the camera. Mehdi says the 10:30 guess was for when we would get our first deployment attempt, and we got very close.  The whale dove just a couple feet out of my reach with the pole.  

A nice view to end the day
Mehdi at home in the local hardware store...wearing the lucky shirt!
We spent hours moving from group to group with the help of the SPAW-RAC crew, trying to ease in close enough to a whale to get the camera on.  By 2:00, we’d had a lot of very close calls but never a whale close enough to try putting the camera on.  We were pretty much out of time – any later and we might have the camera come off in the middle of the night.  We tried one last whale, and we got the camera on its dorsal fin!  A successful deployment!  The suction cup worked better than we had hoped – the first major question of the trip.  We have a few tweaks to make to have the systems perfected but we have the camera back and Mehdi is hard at work right now.  We will be ready for another deployment tomorrow…if the whales are still where we can find them!  Even if they aren’t, I am confident that over the next two weeks the team will be able to collect the data we had hoped to for this first field trip! 

Thursday, July 24, 2014

Dolphins in the coastal Everglades

By Postdoctoral Scientist Dr. Jeremy Kiszka
As the humidity returns, the thermometer rises and the afternoon thunderstorms water south Florida, we are reminded that the dry season has come to an end.  Over the months that spanned the dry season, however, our lab has been investigating dolphins in the Florida Coastal Everglades and associated areas of Florida Bay to answer questions about their behavior, movements and diets. 
We have been keeping a particularly close eye on the dolphins in the waters of the Shark River, Tarpon Bay, Oyster Bay, Joe River, and a 200 km2 stretch of coastal waters spanning east from Cape Sable to the Buttonwood Keys.  In May, three surveys have were conducted to increase sample sizes in Shark River and in Florida Bay, that will allow us to better understand the foraging ecology and ecological roles of dolphins in these areas.  With the 12 new biopsy samples collected we are up to about 35 samples and various analyses are underway, including stable isotopes to determine what and where dolphins are eating and persistent organic pollutants (e.g. PCBs, DDT) and Mercury (Hg). Preliminary results of stable isotope carbon and nitrogen analyses reveal that bottlenose dolphins feed in either coastal marine waters, as well as throughout river systems of the Everglades, from brackish to freshwater environments.
During our expeditions to the Everglades we have been able to observe some very interesting and unique behaviors of dolphins including strand feeding, mud ring feeding (solitary and in groups) and side swimming (in very shallow waters).  Biopsy samples taken from these animals may give us new information about diets specific to these feeding styles and behaviors. 

During mud ring feeding, a dolphin swims in a circle around a school of mullet while creating a ring of mud with its tail.  The mullet try to jump over the ring of mud and dolphins can catch them out of the air!

The nicks and cuts out of the dorsal fins help us identify individuals.

An osprey grabs a meal.

Some dolphins love to forage right next to - or even under - mangrove trees!

Thursday, January 30, 2014

Animal-borne video cameras reveal the secret lives of sea turtles

By Dr. Jordan Thomson, Postdoctoral Scientist

Like many aquatic species, sea turtles can be extremely difficult to observe in the wild so important aspects of their behavior remain poorly known. However, using new, high-definition animal-borne video cameras, we have gotten an astonishing look into the lives of these charismatic yet elusive creatures.

Motivated by a lack of understanding of the basic biology of endangered sea turtles, we used custom-built animal-borne video cameras to study the behavior of green and loggerhead turtles in Shark Bay, Western Australia. The researchers conducted over 120 camera deployments, yielding nearly 400 hours of video footage and an unprecedentedly detailed, first-hand view of turtle foraging patterns, diets, habitat use and social interactions – information vital to effective conservation.

The first peer-reviewed article to emerge from this research, published in the Journal of Experimental Marine Biology and Ecology, reveals strong patterns in turtle behavior associated with seasonal water temperatures (which have long been suspected but have proven difficult to observe). During summer, turtles in Shark Bay were highly active, spending most of their time exploring vast seagrass meadows, feeding, interacting with other turtles and keeping themselves clear of barnacles and algae by rubbing on rocks and corals (see article for video clips). When temperatures dipped in winter, however, turtles’ lives slowed to a crawl as they spent most of their time resting on the seabed and rarely came up to the surface to breathe.

While video analysis is ongoing, several other tidbits and video clips (Green Turtle Video 1) have emerged from this research. For example, green turtles in Shark Bay have a very broad diet consisting of seagrasses, algae, jellyfish and other invertebrates (unlike green turtles in the Caribbean Sea, for example, which eat mostly seagrass) (Green turtle eats seagrass, Video 2; Green turtle eats more seagrass; Video 3; Green turtle eats a sponge, Video 4). Loggerhead turtles feed on hard-shelled invertebrates and appear to be quite fond of blue swimmer crabs – but apparently need some practice at catching them (Loggerhead Turtle, Video 5). Limited rocky habitat in Shark Bay appears to be in high demand for resting and rubbing by green turtles, and sometimes things can get testy (Green turtle fight Video 6). And then there’s this clip of a tagged female loggerhead turtle spurning the advances of an interested male (Video 7) (who eventually decides to give up and try another day).

A valuable and evolving research tool, animal-borne video cameras continue to provide unique glimpses into the lives of poorly understood, and often imperiled, marine wildlife.  Check back later for more on our turtle-cams and the other species we are working on!  For now check out this video of a green turtle swimming past a cow tail stingray.

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