Research Blog Feed
By Gifty Anane-Taabeah, a Ph.D. student in fish and wildlife conservation, College of Natural Resources and Environment, and an Interfaces of Global Change Fellow with the Global Change Center at Virginia Tech
[About the blogger: My Ph.D. research focuses on quantifying the genetic variability within and differentiation between natural populations of Nile tilapia Oreochromis niloticus in different river basins in Ghana. We have very little information on the genetic diversity of O. niloticus outside the Volta system. Furthermore, O. niloticus populations in major river basins in Ghana including the Pra, Ankobra, and Tano currently face diverse threats including habitat destruction from illegal small-scale gold mining activities, overfishing, and pollution. Using a population genetics approach, my research seeks to generate baseline data that will aid in conserving the species’ genetic diversity and local adaptation.]
Today is Wednesday June 7, 2017. I am currently lodging in Half-Assini, a border town between Ghana and our western neighboring country, Ivory Coast. I spent most of my day at Elubo, another border town about 45 minutes-drive from Half-Assini, in search of O. niloticus samples. Wednesdays are market days in Elubo and an opportune time to scout for wild-caught O. niloticus. This is especially important because Ghana shares the Tano River with Ivory Coast and the data generated will be useful for conserving the species in both countries.
I have successfully collected samples from the Pra and Ankobra Rivers, and I am amazed about the morphological differences I have observed among individuals within each river. I am already excited about what I will discover after my genetic analysis. I am hopeful that my research will provide the much needed baseline information about O. niloticus genetic diversity in Ghana, and add to the body of knowledge on the population genetics of O. niloticus in West Africa.
My research also seeks to identify wild populations of O. niloticus with a natural local adaptation to future climate conditions in Ghana. The average water temperatures in rivers vary along the latitudinal gradient of Ghana. Our previous experimental studies using different populations from the Volta River basin have revealed that some northern populations of O. niloticus may already be adapted to high temperature conditions, similar to the future climate conditions expected for southern Ghana.
Given this background, I have spent the last four months setting up and running three separate experiments to quantify the adaptation of different wild populations to varying temperature conditions both under laboratory and outdoor conditions, as well as to quantify the heritability of the growth rate trait from parents to their young.
I have a great local team comprising local fishers, government scientists and graduate students who have helped me with the collection of adult fish, monitoring of their growth and reproduction, and selection of their young for the experiments. I am hopeful that the data obtained from this research will be useful in selecting suitable populations and developing them for aquaculture in Ghana and sub-Saharan Africa.
All photos courtesy of Gifty Anane-Taabeah.
I am chugging café con leche and downing a whole plate of fresh papaya and pineapple while I wait for Dani to pick me up at the hotel. It was a late night, with a delayed flight from Atlanta to Panama City, but I am anxious to get out to the field with Dani and Angie today. Dani arrives and we weave our way through crazy traffic heading east out of the city. Every bus stop has a fruit stand and I implore Dani to stop for guanabana, my favorite tropical fruit, but he says it is too dangerous to pull over at the bus stops, and after watching a few buses pull in and out, I have to admit he is probably right.* We eventually leave the highway at a small town and stop to buy a few giant avocados en route to the field station. A few river and stream crossings later, and we arrive in a tropical paradise.
Dani and I are waiting in the open air “comedor” for Angie to return from scouting out a field site. When she gets there, she immediately starts cooking. We have a great lunch of tortillas and chorizo, with some of our recently acquired avocado. After lunch, Dani and Angie start packing for the hike to the field site. They are doing an important conservation project here—seeing if endangered toads that have been raised in captivity can survive at a site where they used to live. The hardest part of the project, hauling all the enclosures to the site (one per toad) and putting in the toads, was done a few days ago. Today we are going to go check on the toads and swab them, so we can monitor potential infection by chytrid fungus, the skin pathogen that likely drove this species to the brink of extinction in the first place. That swab will also allow us to assess the other microbes on their skin, so we can see how their symbiotic skin microbes change following re-introduction. We think these microbes might play a role in disease resistance, and so we want to track how they might change over time in the field in these toads that are so susceptible to chytrid fungus.
We are hiking up a very steep trail, just outside of the station. I stop to look at a frog (or maybe just to catch my breath). There is so much life in the lowland tropics– so many things to see. Hiking in a tropical forest, as a lover of biodiversity, is like no other experience. Every step brings something new to see… a frog leaping from underfoot, a giant caterpillar, a gorgeous orchid on a branch overhead, an amazing mushroom growing out of a stump, a flock of birds that make a ridiculous amount of noise but can’t be seen, the slightly eery sound of howler monkeys in the distance. We stop to watch two pied puff birds that look like small black and white kingfishers. They are sitting on a branch right next to the trail, near a termite mound and they seem as curious about us as we are about them. We keep moving and are headed downhill now, to a stream. We walk down this stream, on slippery boulders and large cobbles. Dani points out a small frog carrying tadpoles on her back, looking for a place to put them in the stream. It seems a precarious venture for such a small creature in a big stream, and I wish her well. We climb down the edge of a small waterfall that looks like it should be on a postcard, and soon we arrive at a larger stream, where the enclosures are, and the toads. It took an hour to get here and we have a lot to do, so we find the first enclosure downstream and get to work. Dani and Angie carefully check and swab each toad. Most are hiding in the leaf litter inside the enclosures, which is damp to the touch. I watch my students, trying to help a little where I can, and listen to the sounds of the forest—I am reminded of how much I love being in the field, and how that used to be a much bigger part of my job.
“Does everyone have extra batteries for their headlamps?” Angie asks. Dusk is rapidly approaching and we still have about 10 frogs left to swab. We are walking upstream to the next set of enclosures, which are spaced out along the banks as the stream topography allows. I pause momentarily, and Angie says, “Keep walking, please”, with a bit of urgency. I move forward as my brain ticks off the things that might have produced that tone in her voice. Fer-de-lance, bullet ants, jaguar…That is as far as I get on my list before Angie points out the coral snake climbing through some short palms to our right at about shoulder height. It is beautiful with its bands of red, yellow and black, and they aren’t aggressive snakes, so I stop to enjoy it for a moment.** When we arrive at the next enclosure it is nearly dark, and the loud squawking of blue-headed parrots is filling the dusky jungle. Soon it is completely dark, and we are working by headlamp to the plinking calls of hopeful male glassfrogs. The toads are sleeping on top of the palm fronds in their enclosures now that it is dark, so they are easier to find as we finish up our work.
It took us 90 minutes to get back to the field station from the end of the enclosure transect. We walked very carefully, eyes staring for vipers in the leaf litter on the trail as if it was a magic eyes illusion that would spring to life at any instant. At one point, Angie stopped to point out a large tree with a sparse line of bullet ants climbing it, and a few seconds later we all skirted around a bullet ant crossing the trail. We have nothing but respect for the insects given a “4+” for the pain of their sting on a 4-point scale. After shockingly cold showers, we had peanut butter, bananas and crackers for dinner, and maybe a little rum. I climb into my hammock for the night, feeling grateful that I have the opportunity to be here for a few days with these two amazing graduate students in this incredible forest.
**We saw the snake again on the way out, and Dani determined it was a false coral snake, actually a colubrid, but still beautiful.