Mechanisms and consequences of change in aquatic protist communities
Ecology and Biodiversity of Plants and Ecosystems
Final Report Abstract
Change is part of everyday life. For ecological communities changing environmental conditions may cause changes in their structure, for example reduced diversity or a shift toward different sets of species which may be better adapted to the new conditions. In this project, we investigated microfauna communities (e.g. flagellates, ciliates) which live in the small water pools forming in bromeliad plants in the tropics as a model system to detect and quantify the effect of environmental change on communities. We studied how these communities change with altered environmental conditions, for example between different habitat types in Brazil and Costa Rica. In open forest habitats with lower numbers of trees the communities in bromeliads were more different from one another (higher beta diversity) than in closed forest habitats and we found that water temperature and especially strongly fluctuating temperatures across the day have a strong impact on these communities. In the Costa Rican mountains we investigated experimentally how environmental variation, for example along elevation gradients, may change communities. In one study, we found a strong effect of elevation on the abundance of communities, which was stable for a long time even after moving the communities to different elevations. We also found a strong effect of predation by mosquito larvae, however, only when the communities received abundant resources. This strong effect of predation could also be shown for analyses of data on insect communities from many countries, collected by the Bromeliad Working Group (http://www.zoology.ubc.ca/~srivast/bwg/) over many years. In Costa Rica we also studied if insect and microfauna communities in bromeliads are different between bromeliads in the forest canopy and in the forest understory, using a previous data set and own collected data. We could show that, in fact, insect communities do not differ despite certain differences in abiotic parameters, a result that may help justify the approach of focusing on understory bromeliad communities which is used by most bromeliad studies. Natural changes along elevational gradients were furthermore investigated in an observational study in Costa Rica along a very large gradient in three different sites. Microfauna communities showed a peak in abundance at mid-elevation, partly explained by changing environmental conditions along the mountain slopes, while insect communities surprisingly did not change with elevation. We encountered a number of unforeseen problems with our planned laboratory experiments, stemming from difficulties with lab microfauna and bacterial (food) cultures. However, lab experiments on two ciliate species from bromeliads were nevertheless conducted and preliminary results show an effect of temperature and temperature fluctuations on their communities. The software BEMOVI did not yield satisfying results of automated organism identification and counting procedures, so counts were done manually. Overall, our results show that ecological communities are strongly affected by changes along certain environmental gradients, with partly complex interacting effects of abiotic and biotic variables that drive changes in community abundance, alpha and beta diversity and composition. Our results may partly be upscaled from our model system to larger systems and may for example indicate trajectories of change in other communities subject to different types of anthropogenic change such as climate or land-use change. In addition, they may support the conservation of bromeliad microfauna and other small aquatic ecosystems which are often ignored in conservation efforts typically directed at larger species or ecosystems.
Publications
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(2018) Constraints on the functional trait space of aquatic invertebrates in bromeliads. Funct Ecol (Functional Ecology) 32 (10) 2435–2447
Céréghino, Régis; Pillar, Valério D.; Srivastava, Diane S.; Omena, Paula M.; MacDonald, A. Andrew M.; Barberis, Ignacio M.; Corbara, Bruno; Guzman, Laura M.; Leroy, Céline; Ospina Bautista, Fabiola; Romero, Gustavo Q.; Trzcinski, M. Kurtis; Kratina, Pavel
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2015. Dominant predators mediate the impact of habitat size on trophic structure in bromeliad invertebrate communities. Ecology 96:428–439
Petermann, J. S., V. F. Farjalla, M. Jocque, P. Kratina, A. A. M. MacDonald, N. A. C. Marino, P. M. de Omena, G. C. Piccoli, B. A. Richardson, M. J. Richardson, G. Q. Romero, M. Videla, and D. S. Srivastava
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2015. Resources alter the structure and increase stochasticity in bromeliad microfauna communities. PloS ONE 10:e0118952
Petermann, J. S., P. Kratina, A. A. M. MacDonald, N. A. C. Marino, and D. S. Srivastava
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2017. Environmental control of the microfaunal community structure in tropical bromeliads. Ecology and Evolution 7:1627–1634
Kratina, P., J. S. Petermann, N. A. C. Marino, A. A. M. MacDonald, and D. S. Srivastava
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2018. Different in the dark: The effect of habitat characteristics on community composition and beta diversity in bromeliad microfauna. PloS ONE 13:e0191426
Busse, A., P. A. P. Antiqueira, A. S. Neutzling, A. M. Wolf, G. Q. Romero, and J. S. Petermann
