Monday, September 5, 2011

Raison d'etre? - The reason for being?


The crew is back home. Boats are dismantled, dive gear washed, probes calibrated, and data entered. Clothes packed (or donated), labs locked and good-byes exchanged. The work has completed for this season, but the work is not completed.  It is time for sore bodies to rest, indulge in soft mattresses, and cold beverages.  We will easily put the lost pounds back on our sapped frames.  Interestingly, we will miss sand in our dive booties and a "proper" cup of tea. Hard to believe, but we will.

We have learned much and have been reminded how much we have to learn. The first steps toward stewardship of our planet are not monumental ones. They are subtle and fleeting. The awareness of a brightly colored bird rarely seen. The appreciation of a stiff breeze moments before the noticeable infrequent  rain storm. The twist in your stomach when you realize your childrens' experiences will be different than your own - and you hope they are as good. It is no small wonder we are mis-stepping our handling of that global stewardship.

In Dr. Goodall's words, "if we are the most intellectual creature that has every walked on this planet, how come we are destroying that planet?"

Yes, the work has completed for this season, but the work is not completed.

Monday, August 15, 2011

Long live the water cobra!

posted by Pete McIntyre (U of Wisconsin)

One of the most intriguing species endemic to Lake Tanganyika is the water cobra, an aquatic cobra that seems to feed exclusively on fish.  It hunts underwater, systematically probing under rocks until it can corner some hapless cichlid.

For years, there has been some concern that water cobras could be imperilled by getting tangled up in fishermen's nets.  Along much of the lake shore, there probably have not been enough gill nets used to have a major impact on the cobras.  However, those of us working near Kigoma have noticed a distinct drop in the number of cobras we see while working in the nearshore zone over the last decade.

The last time that I had seen a water cobra was 2002, so I was thrilled (in multiple senses) to see a monster today.  When I met up with the team this afternoon after counting fish at other nearby sites, George told me that he had seen a large cobra about 100m up the shore.  I was relieved to hear that the snakes are still present in at least small numbers, but we had little time to talk about it because we needed to turn to catching the last few fish needed for the day.  George quickly got two Neolamprologus toae, and I found a third to complete the collection.  On my way to shore to hand the fish off to Ben and Ellen, I saw a tree branch among the rocks that I hadn't noticed before.  Then it moved!

The cobra was by far the largest I have ever seen.  I am confident it was nearly 3m long, perhaps more.  I didn't get a look at the head, but the neck had 7 black bands compared to the 2-4 that i have seen on smaller cobras.  Its girth was shocking--the size of my upper arm--and more than a bit intimidating.

Thankfully, these beautiful snakes rarely if ever bite anything but fish.  This one vanished among the rocks, and we did not see it again.  It was heartening indeed to come across my first water cobra in a decade, suggesting that they have not been extirpated from our study area.  Alas, as we left the site an hour later, a fishermen was deploying a gill net in exactly the area where we saw the snake.  We can only hope that it can continue to elude these inadvertant death traps.  Indeed, these marvelous predators may now be sensitive indicators of the few remaining sites where nearshore fishing pressure has not yet intensified...  . Long live the water cobra!!!

Sunday, August 14, 2011

It’s a whole different lake at night…

posted by Pete McIntyre (University of Wisconsin)

Led by our trusty colleague and field helper George Kazumbe, the team has now gone diving and snorkeling at one of our main study areas at night on two occasions—and what a difference it has made!  Whereas we had believed that zooplankton are scarce in the lake, we were amazed to find that on a nearly moonless night, the water along the coast was heaving with small shrimp, tiny copepod crustaceans, and larval sardines.  These small animals (often lumped under the term zooplankton) have long been recognized as an essential link in the food chain, but our extensive work during daylight hours always led us to believe that intensive predation by the fish plus the small amount of algae in the water was enough to limit the populations of planktonic animals.  Apparently we were wrong!

In retrospect, it makes sense that there must be loads of copepods and shrimps because these small animals are a staple in the diet of about half the fish species along the shore.  Nonetheless, the difficulty of finding them during the day had convinced us that they never achieve large population sizes.

Instead, it turns out that there are plenty of zooplankton, but they are able to hide very effectively during the day (from both fish and human researchers!).  At night, when the moon is dim, they swarm forth to feed on the tiny algae suspended in the water (phytoplankton), and on each other.

Along with this revelation about nearshore zooplankton densities, we were surprised to see both how many species of small catfish were swimming around (at least 6 species, twice the number what we had found from all previous sampling), and how few eels there were.  The nocturnal catfishes were dominated by small claroteid species (most less than 4 inches in length), along with some walking catfish (Clarias) and upside-down catfish (Synodontis).  I had expected to see more Synodontis and Clarias, but in fact we see more of both groups during the day than we did at night.

The lack of eels was intriguing.  Spiny eels are common predators along the shoreline of Lake Tanganyika (and most rivers and lakes in Africa and Asia), and I suspected they were primarily nocturnal.  As it turns out, we saw an abundance of one species that is rarely observed during the day (one with beautiful rings of brown and black along its body), but not a single individual of the other 5-6 species we have found at the site.  These observations have convinced me that the most effective way to count the eels is probably from daylight observations, rather than night-time work.  It is odd that most species of this group of predators do not take advantage of the opportunities afforded by sleeping cichlids on the bottom, which would seem to offer easy pickings for a fish-eater.  However, it does help to explain why the eels have such good vision—they are remarkably hard to catch because they can see our thin-mesh nets much better than most of the cichlids do!

Perhaps the biggest surprise of all was observing two kinds of electric fishes.  We knew there would be electric catfish, which eat fish and shrimp after stunning them with an intense electric shock.  Collecting those by SCUBA was a bit nerve-wracking, but George and I got two without any electric tingles (or jolts).  But we also were amazed to see several different groups of weakly-electric fish, the elephant fishes (mormyrids).  They were all the same species (one lacking an elephantine snout), and proved impossible to catch.  These fish are about 3-4 inches long, and they use weak electrical pulses to communicate with each other, navigate complex environments, and find their prey.  In rivers where I have caught these fish before, they eat mostly insects and worms on the bottom.  However, the Tanganyikan species seemed to be well up in the water column, suggesting that they are catching the shrimp and other zooplankton.  Interestingly, they were also right against the shoreline along intricate rock walls and crevices, so perhaps that is where they hide during the day.

While George and I chased fish, Ben and Ellen used an ultra-fine net to collect zooplankton samples.  Ben found that there were far fewer zooplankton in the water on our second trip than on the first day, but still more than we had expected originally.  He also found large quantities of a beautiful diatom that forms colonies with hair-like spikes radiating outward from a central sphere, sort of like a sea urchin but with a total diameter far less than 1/100th of an inch!

All in all, it was marvelous to see the nocturnal life of Lake Tanganyika.  However, it’s also very exhausting after a long day of work in the water!  So we’ll stick with daylight work for the most part…

Thursday, July 28, 2011

The Road Taken

The approaching long August days of summer bring with them bittersweet thoughts. As I prepare to leave Tanzania, a place of warmth and a love for life, while anticipating going home to my family, I am filled with "Karibu" toward the people here who have allowed me to experience a life like no other.  I have come to assume them, making their existence a part of my own. I have spent countless hours in the cool waters of an ancient lake. I have climbed mountains that watch over this lake. I have sat quietly with chimpanzees who share much more with us than just a place on this planet. I have spoken with people far more committed than I am to changing this world for the better. It is all humbling. As time goes on, I will find it hard to remember the details of day-to-day life here, but I will move through my life differently because of this time spent. I will unlikely see the face of Africa again, but the African sunsets on my face will warm me forever. 

photo: E. Gaines

Wednesday, July 27, 2011

Work Intensifies at Lake Tanganyika

Sunset on Lake Tanganyika (photo by E Gaines)
The work on the lake seems to have intensified with the arrival of two more team members, Sam Drerup, a graduate student from Wright State University, and Peter McIntyre, co-principle investigator from University of Wisconsin.  Several experiments and lots of data are being gathered, and everyone is putting in long hours on the lake and working late into the night at the lab.
Yvonne, Ellen, Sam, and Ben assist the divers from the Zodiac boats. (photo by E Gaines)

Ryan and Len measuring rugosity (roughness and variation in the bottom of the lake).  (photo by E Gaines)

Yesterday Yvonne Vadeboncoeur's crew was on the lake before dawn and returned to the lab after sunset.  Pete's crew had to do emergency repairs on their boat before getting on the lake to gather samples of fish with George Kazumbe.  George is recognized as an expert of Lake Tanganyika fishes.  He is an excellant scuba diving guide, and runs Maji Makumbwa (Big Water), an Eco-tourism business in Kigoma (PKazumbe@gmail.com, majimakubwa@gmail.com, +255 755 662129).  While we have been here, scientists from Princeton, Oklahoma State, University of Arizona as well as Wright State and University of Wisconsin, and others from Europe have passed through to consult with George.
George Kazumbe, Lake Tanganyika fish expert, scuba guide, and manager of Lake Tanganyika Ecotourism & Biodiversity Conservation Project    (photo by E Gaines)
       Last weekend, the team had a wonderful dinner in a village outside of Kigoma at the home of Renalda's brother.  We had a great time and enjoyed the food and good company of Renalda's family.
The whole team!  Back row: Sam Drerup, Renalda Munubi, Elliot Gaines, Yvonne Vadeboncoeur, and Ellen Hamann.  Bottom row: Ryan Satchell, Peter McIntyre, Len Kenyon, and Benja Kraemer.
 Elliot Gaines  July 27, 2011

Tuesday, July 26, 2011

Meeting and Passing a World Away

photo: E. Gaines
While traveling between Dar and Kigoma, Dr. Elliot Gaines photographs the demands of life and the resilience to it.
photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

 photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

photo: E. Gaines

Saturday, July 23, 2011

A Post from the P.I. Yvonne Vadeboncoeur


As one of the principle investigators on the Lake Tanganyika Littoral Project, I spend most of my time figuring out the logistics of getting science done while keeping seven people reasonably well-looked after in paradise.  Given that its paradise this ought to be easy, but as our fish-man George Kazumbe always says TIA. This Is Africa.  Roughly translated this means – don’t expect anything to be on time, as planned, or uncomplicated. 

So why bring all of these folks to East Africa?  Lake Tanganyika is one of the most amazing freshwater ecosystems on earth.  It is a huge ancient tropical lake that boasts not only a stunning diversity of cichlids, but also snails, crabs, shrimp and jellyfish.  When Europeans first encountered Lake Tanganyika, they speculated that it had once been connected to the ocean, which is an understandable mistake given its fauna.

The lake is what we would normally call “unproductive,” meaning that the water doesn’t have many of the nutrients that allow photosynthetic organisms (in this case algae) to grow. “Unproductive” lakes are what you would think of as “clean”--nice clear water with no green pond scum.  The clear water allows photosynthesis to occur to great depths in the lake.  When plants photosynthesize, they use sunlight to convert carbon dioxide and water into carbohydrates - which the plant uses to grow.  Even though this process of making life with light occurs wherever there is light on earth, I find it miraculous. Non-living (or inorganic) compounds are transformed into living tissue using chlorophyll and the energy from sunlight.

If you have house plants or a garden, you know that you don’t give plants carbon dioxide to make them grow faster, you give them fertilizer or manure. These fertilizers contain nitrogen and phosphorus (N & P) which are critical for plant growth. So what has all this to do with fish and Lake Tanganyika? As I said, Lake Tanganyika would be categorized as “unproductive” because nutrients like N and P are extremely scarce in the water.  However, the algae on the rocks are growing crazy fast and the fish that eat the algae are very abundant.  In fact, densities of fish in Lake Tanganyika rival those of a coral reef.  So, the lake ISN’T unproductive with respect to fish, and the algae themselves are very productive, but the fish eat the algae pretty much as fast as they can grow. We are trying to figure out how this seemingly nutrient poor lake supports all these fish and this high algal growth.
Dr. Vadeboncoeur measuring photosynthesis (photo by E Gaines)

We think that in the very shallow waters at the lake edge, the algae get fertilized by the fish pee and poop. Basically, the fish are critical to fertilizing their own food source, much as we would fertilize a farm or garden.  Take away the fish and you take away the nutrients, and the algae would not be able to grow as well. The fish “store” nitrogen and phosphorus in their bodies and leak the nutrients out is small amounts that help the algae grow.  The algae, in turn, use photosynthesis to create carbon compounds that the fish need to meet their energy demands.  It gets pretty circular if you think about it too hard, but ecologists like getting mesmerized by cycles.
Fish eating algae (photo by E Gaines)

My crew spends all day underwater measuring photosynthesis of algae growing on rocks and watching fish.  We try to detect patterns between fish abundance and algal growth. Ecologists use common things in ways that they were never intended in order to understand how organisms interact with their environment.  Limnology was once described as “the science of ropes and buckets”.  Now we would add PVC, duct tape and zip ties to that description.  I get people to work with me by telling them about the fish and the SCUBA diving,  Then I ask them to haul around all these weird contraptions to do these underwater experiments.  For the first few weeks, we were measuring photosynthesis.  I won’t go into details, but we used a bunch of sausage weights to hold our chambers against the rocks. A sausage weight is the circular tube of fabric filled with lead shot.  We use about 130 lbs of sausage weights. Len and Ryan got pretty tired of hauling them up from 5 m at the end of a long day underwater.  So they were happy when we moved on from photosynthesis to “rugosity”.  Rugosity is a measure of the lumpiness of the bottom of the lake.  Fish like to have places to hide, so the more rocky areas are preferred habitats for most of the fish we are studying.  Measuring lumpiness sounds innocuous and without the sausage weights, our boat got much lighter.  Sometimes we even went a little fast. 
researchers work with tropical fish all around (photo by E Gaines)

But how to measure lumpiness?  Well of course you take a 10 m long chain and drape it over all the rocks and compare the length of chain you use with a straight line distance between the your beginning and ending point.  Now instead of moving buckets of lead around, they are doing underwater surveying with an unwieldy chain.  Ryan decided today that he misses doing photosynthesis.
Jane Goodall and Yvonne Vadeboncoeur (photo by E Gaines)