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

Freshwater oyster or crocodile eggshell?

One of the beautiful but lesser-known creatures who lives in the Mara is Etheria elliptia, the freshwater oyster. We often find their shells on the river bank, but we've only ever found one alive, despite many hours spent kicknetting and digging around in the river. They are a type of freshwater mussel, which play important roles in river ecosystems as filter feeders and natural filtration devices. They can form a cement-like attachment to rocks or other shells (like the two attached shells in the photo below), which is remarkably strong and difficult to break (a friend broke a wooden rungu trying). They lay down their shells in layers, and I have long been interested in analyzing the elements in the different shell layers as a type of data recorder over time for conditions in the river. However, in order to date the layers, we would have to find live specimens. 

We have been told by several Maasai that they think the shells are crocodile eggshells, a description which I love, as it is exactly what I would imagine a crocodile eggshell would look like if I didn't know that they are actually flexible and almost paper-thin. But couldn't you just imagine a little crocodile, with bony scales and needle-sharp teeth, crawling out of one of these?

Etheria elliptica shells on the bank of the Mara River

Welcome to the Mara, Ella!

Ella Jourdain, an undergraduate student at Yale and a participant in our NSF-funded Research Experience for Undergraduates program, just arrived in the Mara. Ella will be doing research this summer on the influence of hippos on greenhouse gas emissions from the river, using both field and experimental approaches. Ella is from NYC and has never been camping before, but she is excited to spend her summer in a remote field camp with no electricity or running water-- pretty awesome! Karibu Ella!

Ella Jourdain

Streams up and running!

We set up our streams on the concrete pad, filled them with water, lined them with sand and gravel, and plugged in the motors. We watched the water start to lazily move around the 18 little rivers, riffling over cobbles, moving sand around the bends, and we took a moment to celebrate. We got our artificial stream experiment up and running in the middle of the Maasai Mara! 

Will they survive for the duration of the experiment? No idea. 

David, James and Chris celebrate

Our artificial stream array in the middle of the Mara

And some fencing....

We were planning to set up 18 artificial streams in the middle of the Maasai Mara, fill them with water, put rotting wildebeest meat in several, and run an experiment for several weeks during which three rows of propellers had to turn 24 hours a day to circulate the water and nothing in the streams could be disturbed.

There's a lot of very large wildlife in the Maasai Mara, including a lot of animals that might be attracted to either water or the smell of rotting meat.

These two statements seem to be incompatible with one another. However, Brian assured us it could be done, and he's never been wrong before. We figured we would at least need a good fence and maybe some cowbells for good measure.

James helps set up the fence around our streams

James is really excited this is coming together

6,500 liters of water

Water, water everywhere, and not a drop for our artificial streams...

This is how I felt as we embarked on the next challenge - how would we get enough water to fill our 18 streams with 60 liters each and conduct a 50% water change every other day (kids, take note... this is why math is important!). There was water at the Mara Conservancy headquarters, but it came from a borehole and is salty, and we weren't sure how that would impact our experiment. There was water in the nearby Mara River, but it was in the realm of large wildlife and thus full of hippo poop. One thing we were planning to test was the influence of hippo poop on the diet of aquatic insects, so we needed control water that didn't already have hippo poop in it. There was freshwater in a nearby borehole, but many people rely on it for drinking water and it occasionally runs low, so they weren't comfortable with us using so much water from it. There was water in the Mara upstream of hippos, but that was a 2.5 hour drive away on terrible roads, so it would be a logistical challenge to get it into our camp. Did you say logistical challenge?! We're in!

After about a million phone calls to everyone we know, and all of their friends, and all of their acquaintances with trucks, we finally found someone willing to sell us some water tanks that they could transport to the Mara, and someone else willing to drive a water tanker 2 hours from Narok, fill it up from the Mara upstream of hippos, drive the water 2.5 more hours to our camp, and fill up our tanks. I'm pretty sure everyone thought we were crazy, but we were on our way to having 6,500 liters of water!

Artificial streams in the middle of the Mara

We set up our first artificial stream experiment in 2014, using a portable artificial stream array we built in Kenya. It was so exciting to be able to conduct rigorous experiments in the field, with controls and replication, which is usually quite difficult to do at the ecosystem scale at which we normally work. In 2014, we set up the stream array at the Mara River Water User's Association in Mulot, which is a grassroots water resource management group. Working there was a great way to stay in touch with local stakeholders in the basin and involve them in our research, and they had electricity and a water pump and holding tank that made running the streams fairly easy.

We were excited to use the artificial streams again this year, but we were hoping to stay closer to our camp, which is in the middle of the Mara Conservancy. We also planned to expand our stream array to 18 streams. But how could we get 18 streams full of water and running continuously at a remote field camp with no electricity or running water? Ah, a logistics challenge is hard for us to resist!

The first step, which is often the case, was to consult Brian Heath, CEO of the Mara Conservancy. In addition to managing the Mara Triangle, Brian is  a consummate naturalist, logistics expert, and supportive friend, whose advice and guidance has been critical to our success more times than I can count. Brian generously offered to let us use a vacant concrete pad located near the Conservancy headquarters, and we had a good start. The manager from the nearby Mara Serena lodge graciously allowed us to use their electricity for the experiment. Now, all we needed was water.

Crabs in the Mara?

During the food web short course, we had several great scientists from the National Museums of Kenya join us, including Laban Njoroge, Head of the Invertebrate Zoology section and an expert in aquatic macroinvertebrates, and John Kochey, a scientist in the Invertebrate Zoology section and a doctoral student studying freshwater prawns. John brought along some prawn traps to set in the river, and at the New Mara Bridge, on the border of Kenya and Tanzania, we caught a crab! We have seen a similar type of crab in the upper Mara, but we have never seen these in the lower Mara, and it turns out this is the first time this species has been documented in the Mara. It is Potamonautes niloticus, which is found within the Nile Basin, including Lake Victoria and its tributaries. It's a beautiful animal, with an olive green back and bright red claws tinged with blue. It's so exciting, after all the time we have spent in the Mara, to still be finding new animals there, especially one as unique as this.

Food Web Short Course

This year we taught our first short course on food webs and stable isotope ecology in the Mara River. The course was taught by myself, David Post, Emma Rosi-Marshall and Frank Masese, with funding from the National Science Foundation. We had 12 participants from Yale University, the National Museums of Kenya, Egerton University and Eldoret University. Some of the course participants were senior scientists or professors interested in learning more about these topics, and others were undergraduate or graduate students still planning their research. The course began with a day of lectures, followed by three days of a field sampling campaign, and then a final day of data analysis.

It was a really wonderful group of scientists and colleagues, all of whom work on different areas of freshwater ecology, and we had a wonderful time together in the field! The best part about the course was that everyone had different areas of specialization, so we all learned from one another.

Our outdoor laboratory

Searching for macroinvertebrates

Sorting bugs

Electroshocking for fish

Setting gillnets for fish

Streamside lecture

The requisite breakdown

Outdoor laboratory #2

Electroshocking for fish

Picking bugs out of hippo poop

Sampling with an armed ranger

Collecting wildebeest bones to sample biofilm

Lecture on aquatic macroinvertebrates

The team