Sundowner farewell

One of the great traditions in East Africa is the sundowner, where you head out into the savanna, armed with a box of wine or a cold Tusker and some cheese and crackers if you're lucky, and watch the sunset. It's hard to describe the splendor of this moment, with the grassland turning golden in the last moments of light; the streaks of red, purple and gold reflecting across the wide open sky; the silhouette of elephants in the distance. It seemed the perfect way to send Ella off after a great and successful summer of field research. Kwaheri Ella and thanks for a wonderful summer!

Ella watching the sunset from the roof of the Land Rover

Testing hypotheses in artificial streams

Ella has been able to collect detailed data on gas emissions from 13 hippo pools, in addition to the 12 hippo pools we sampled last year. This will give her a nice range of hippo density and river flow level in order to test how these two factors influence gas emission levels. However, all the variability often present in the field can often make it difficult to accurately determine the influence of various factors, so Ella designed an experiment in the artificial streams to test her hypotheses more directly.

She added blackwater from the bottom of a very concentrated hippo pool to the artificial streams in varying concentrations.

Ella adding black water to the artificial streams

Then she ran the streams at different velocities.

Ella's artificial stream experiment

At various time points, she collected water samples from each stream and collected dissolved gases from each sample into vials which will be analyzed back at the Cary Institute. Actually, we had a team of 4 people working as fast as possible every 45 minutes throughout a whole day to collect the water samples at specific times. Again, we were lucky to have a great team!

Ella collecting a gas sample

We couldn't analyze any of the gas data in the field, so we won't know the results of this experiment until the fall, but all of the dissolved oxygen data from the streams suggest we were successful in capturing the range of conditions we were hoping for. Can't wait to see how all of this comes together!

Greenhouse gases from hippo pools

Over the last few weeks, Ella has been collecting water samples from a lot of different hippo pools in order to measure how hippo pools may contribute to the emission of greenhouse gases. Hippos load a lot of carbon into pools through feces, and as that feces decomposes, it uses up the oxygen in the water and the decomposition process emits greenhouse gases like carbon dioxide and methane. Ella is studying how the number of hippos and flow of the river influence the quantity of greenhouse gases being emitted. 

To collect these data, Ella has had to collect water samples from a lot of different hippo pools, which can be a... let's say... exciting adventure. Hippos are the most dangerous animal in Africa, and it is particularly dangerous to get between them and the river. The easiest way to access a hippo pool in the Mara is to follow a hippo trail down to the river's edge, and crouch there while you fill your sample bottle, keeping an active lookout for hippos and crocodiles. We always hire an armed ranger and spend a lot of time scouting a hippo pool before we collect samples there, and we always make conservative decisions about which pools we feel we can sample safely, but it is still an activity that really makes you feel alive. Ella handled it like a complete pro!

Ella collecting a water sample from a hippo pool

Much of the sample processing needs to be done as soon as possible, so we take a mobile lab in our Land Rover and do a lot of chemistry in the field. However, some samples need to be analyzed later in our lab tent (affectionately called the Lady Cave, because of all the hours I have spent doing chemistry in there, it's small cave-like interior, and the tendency of bats to roost in and around it). Here's Ella busting out some serious field chemistry in the Lady Cave, late into the evening, equipped with a head lamp to see the readings. Epic!

Late night chemistry in the lady cave

Low cost sensor course in Tanzania

In August, Chris taught a course on low-cost sensor technology for the Tanzania water resource management authorities. This course was part of SELVA - the Serengeti Lake Victoria Sustainable Water Initiative for the Mara River - which is run by our friend and colleague Beth Anderson at FIU. Chris taught the course participants how to build low-cost water depth and water quality sensors using the open-source Arduino platform, and then the team was going to deploy various loggers at sites throughout the basin. This technology is so powerful, especially in places like East Africa, because it allows people on the ground to build and maintain their own sensors, rather than relying on expensive "black box" instruments that have to be shipped off for repair at great expense. Chris has already done some really great work training people in Arduino sensors in the Kenyan portion of the Mara Basin as part of MaMaSe - the Mau Mara Serengeti Sustainable Water Initiative - and this is an exciting new extension of that project. Ella was interested in learning about low-cost sensor development, so she attended the course.

Ella at Lake Victoria

For me, this meant a lovely week off hanging out with Lily in the charming lake-side town of Musoma. I love this town! It's right on the shores of Lake Victoria, so there are beautiful beaches, delicious fish, and a laidback beach town vibe. Musoma is located very close to the Mara Wetland, where the Mara River flows into Lake Victoria, so we have visited here a number of times. We currently have an ongoing project with WWF analyzing sediment cores in the Mara Wetland, so it was a great opportunity to visit the wetland as well and check in with our colleagues.

Beach on Lake Victoria

Musoma is also an amazing place to shop for kitenges, the brightly colored and boldly patterned African fabrics that many women wear. I love shopping for kitenges, and I was excited to get Ella into it. We couldn't resist having a few outfits made for us in the market.

Ella visiting with a seamstress in the market

Can we make a hippo pool in a bottle?

This summer Chris set up one of the big experiments for his dissertation. He is interested in studying the influence of the microbial community on biogeochemical cycling in the bottom of a hippo pool, and the interacting effects of carbon loading and microbial community structure on those effects. He came up with a really clever way to test this by developing small "hippo pools" in 1 liter bottles, which allowed him to have lots of replication across different treatments. In total, he set up around 150 bottles!

Chris weighing hippo poop into a bottle

We sampled the bottles for about 12 different parameters at various time points over a few weeks. We could see some of the results immediately in the field as we collected the data, and it was really exciting to watch the changes in the different treatments over time. A lot of additional data will be analyzed from this experiment back in the lab at Yale. 

The team at work

It was a ton of work, but the preliminary results are really interesting. We saw some of the changes we expected to see, and others that were a complete surprise. Unexpected results are often the most exciting in science because they suggest new hypotheses and mechanisms you may not have considered already. We also had a great team, which makes all the difference. Everyone had a job, James played DJ on his ipod, and we had a lot of fun!

Team Hippo Pool

The migration

We drove up to the Old Mara Bridge today and could see huge expanses of the wildebeest herd as far as the eye could see, meandering across the savanna in straight lines, as they follow individuals they've seemingly randomly picked as the leader. 

James' Farewell

After 6 weeks of studying, sampling and running an experiment in the Mara, it's time for James to head home. For his farewell dinner, we pulled out all the stops with bacon cheeseburgers and cold Tuskers! 

Thanks for a great summer James! See you back at Yale!

Emergence

Our little streams continue to run beautifully, and so far nothing has disturbed them. Geemi and James have been taking turns spending the night there to help further deter wildlife, and they have both awakened on different nights to find elephants and buffalo grazing remarkably close to their small tent. The other night I received a text from James, telling me that he had gotten out of his tent to start the generator (that runs the streams when Serena power is off), and he had found a buffalo just a few meters in front of him, between him and the streams. He asked if he should go ahead and leave the tent. That's a dedicated student! For the record, I told him no:)

James and his streams

James is interested in how hippo feces and wildebeest carcass influence the river food web, so he has stocked the streams with different animal inputs and aquatic insects from the river. He is sampling the insect's body tissue over time, to see what they are eating. He also has set up nets over each stream to catch the insects after they metamorphose and leave the water as winged adults to see what emerges from different streams. 

James sucking bugs out of stream nets with an aspirator

Each morning is a hunt for insects inside each net, which James sucks out into a bottle (or sometimes your mouth on accident!) through a handheld aspirator. Each stream gets its own bottle for storing the emerged insects. At the beginning of this experiment, we weren't sure whether we would be able to successfully rear any insects, but James has been catching tens to hundreds of emerging insects each day, and already has started to see some interesting emergence patterns between treatments. So exciting!

Emerged insects from different stream treatments

Thank you Caitlin!

It's been a really busy few weeks! James's experiment is underway, Ella is busy collecting samples in the field and Chris is getting ready to start a big experiment. Fortunately, our friend Caitlin Staley came in to help with fieldwork this week. Caitlin is a senior in high school in Nairobi, and she is interested in pursuing a science degree in college, so we were excited to give her some field experience in ecology... and super grateful to have her help!

Caitlin doing chemistry in the field

The Yale Mara Field Crew

We have had a great team of folks in the field this summer. David was able to come for 3 weeks, to help teach the food web course and start two big experiments, and it was so great to have him in the field for that long. His visit also overlapped with both Ella and James's trips, so we had our full Yale team together. Good folks make all the difference in fieldwork, and this season, we truly couldn't have had a better team.

Ella, David, James, Amanda and Chris