Tropical peatlands represent a large pool of terrestrial organic carbon and are found in Asia, Africa and South America. They are also under threat from the effects of burning, drainage, deforestation and climate change. In 2011, I received a Royal Society research grant to investigate peatlands in Amazonia. Until then, I had carried out most of my research on peatlands in Ireland, so this would be a bit different! In recent years, a wide variety of peatlands have been found in Amazonia including domed nutrient-poor bogs as well as nutrient-rich swamps. However, our understanding of the ecological and hydrological dynamics of these systems remains poor. The focus of our new research project would be to see if some of the methods we use for reconstructing the ecological and hydrological dynamics of peatlands in the Northern Hemisphere can be used in Amazonia and also in tropical peatlands more widely. Testate amoebae (single-celled animals with a shell) are very sensitive environmental indicators in northern peatlands; we set out to test if this was the case in Amazonia.
Three of us (Ed Turner, Chris Williams and I) set out from Leeds with a variety of equipment to Iquitos, Peru via the capital Lima, for our research at Aucayacu, the largest, oldest peatland that has been discovered in Western (Peruvian) Amazonia. We arrived in Iquitos and had a day or so sorting out our plans before heading up river. One of the problems we encountered was the lack of guttering and cling film for holding core samples! We managed to get some indoor plumbing pipes sawn in half in a DIY shop and after a lot of searching managed to buy an industrial roll of cling film.
Along with our colleagues at IIAP (Instituto de Investigaciones de la Amazonía Peruana) we headed up the Rio Tigre followed by the Rio Marañon for about 1 day (camping overnight in the village of Bellavista). We employed two local villagers to help with cooking, cleaning, machete work and coring. We headed further up the Rio Tigre and then to a small black water stream (i.e. water high in dissolved organic carbon suggesting there are peatlands somewhere upstream). After a very long, winding journey we came to our hut on the edge of the Aucayacu peatland. Camping in the hut was a lot of fun with many creatures coming to visit including spiders, tarantulas, cockroaches and snakes. There were lots of interesting noises in the rainforest at night and it could get a little spooky, especially following an evening of ghost stories, myths and legends of the rainforest led by our botanist Elvis Valderrama. On one occasion our cook Lucho caught a rat and served it for breakfast. I stuck to the porridge on that occasion!
We worked on the peatland every day we were in the rainforest. Aucayacu was quite unlike most northern peatlands I had visited in that it had a dense cover of trees with thin-trunks (pole forest). I suppose the closest northern equivalent I had seen previously would be a carr wetland. The villagers helped us hack a path through the trees with machetes and we marked out our sampling transect. We had to change the direction of the transect at one point to avoid an area of fallen trees the locals referred to in Spanish as “a house for snakes”. Enough said! We collected litter samples for testate amoebae and measured many variables along the transect (water table depth, pH, electrical conductivity of water, vegetation composition) and surveyed the topography of the peatland. We found that there were shallow pools in places along our transect as well as drier areas, sometimes in flat areas or in ridges or small hummocks. We took samples for testate amoeba analysis from the different environments to encompass the hydrological gradient within the site. We also took a series of cores from the peatland to investigate the environmental history and development of the site during the Holocene. The field days were hot, long and dirty but very rewarding. We finished the fieldwork in just over 2 weeks then packed up all our samples and equipment and headed back to Iquitos. We send our samples back to Leeds by courier (which costs a ridiculous amount of money) and spent a few days site seeing before heading home.
The next year involved a lot of laboratory work to count and identify testate amoebae in the contemporary samples and peat core. The analysis of testate amoebae was done in collaboration with Monika Reczuga and Mariusz Lamentowicz at Adam Mickiewicz University, Poland. We recently published a paper in the journal Microbial Ecology that showed that testate amoebae have potential as hydrological indicators in tropical peatlands, as some species are diagnostic of particular habitats, e.g. pool environments. However, much more work is needed to investigate the ecology of testate amoebae in the tropics. I am off to the San San Pond Sak peatland in Panama this November to continue the work!
Please contact me firstname.lastname@example.org if you would like a copy of this paper:
Swindles, G.T., Reczuga, M., Lamentowicz, M., Raby, C., Turner, T.E., Charman, D.J., Gallego-Sala, A., Valderrama, E., Williams, C., Draper, F., Honorio Coronado, E.N., Roucoux, K.H., Baker, T., Mullan, D.J. 2014. Ecology of testate amoebae in an Amazonian peatland and development of a transfer function for palaeohydrological reconstruction. Microbial Ecology 68, 284-298.
Photos courtesy of Ed Turner and Chris Williams, University of Leeds