Spatial and temporal patterns of microbial mats and associated invertebrates along an Antarctic stream
Microbial biofilms are biological hotspots in many alpine and polar ecosystems, but the controls on and functional significance of their fauna are little known. We studied cyanobacterial mats and the underlying sediment in a glacial meltwater stream in the McMurdo Dry valleys, Antarctica. We investigated mat biomass (total and phototrophic), diatoms, and micro-meiofauna (nematodes, rotifers, and tardigrades) at nine sites along a 1670 m stream reach in a cold, low-flow growing season, and in a warmer growing season in which peak flows (above 100 L s−1) scoured the mats. Diatom and invertebrate communities were not related, but mat biomass in the low-flow year was negatively related to nematode abundance, including that of the omnivore Eudorylaimus. In the high flow year that followed, invertebrate abundance was reduced in the mats, diatom community structure was altered, and mat biomass was higher. The difference in invertebrate abundance between years was greater in mats in upstream reaches, where the greatest increases in flow velocity may have occurred, and was negligible in mats in downstream reaches as well as in the sediment beneath the mats. Integrating our results with previous findings, we generate two predictive hypotheses to be tested in glacial meltwater streams: (1) under peak flows invertebrates decline in the microbial mats, while (2) the sediment beneath the mats is a refuge from the flow disturbance. Our results also suggest that, under stable flow conditions, microinvertebrate grazers could exert top-down control on microbial mat biomass.
KeywordsDiatoms Disturbance Dry valleys Epilithon Microfauna Streamflow
We thank Uffe Nielsen, Karen Seaver and Tracy Smith for helping with sampling and invertebrate identification, and Eric Parrish for updating the field site map. This research was conducted as part of the McMurdo dry valleys Long Term Ecological Research project, NSF OPP Grants 9211773, 9810219 and 1115245. Geospatial support for this work was provided by the Polar Geospatial Center under NSF OPP awards 1043681 and 1559691. Comments by three anonymous reviewers helped us improve the text.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Vijver B, Beyens L, Lange-Bertalot H (2004) The genus Stauroneis in the Arctic and (sub-) Antarctic-regions. Bibl Diatomol 51:1–317Google Scholar
- Derlon N, Koch N, Eugster B, Posch T, Pernthaler J, Pronk W, Morgenroth E (2013) Activity of metazoa governs biofilm structure formation and enhances permeate flux during gravity-driven membrane (GDM) filtration. Water Res 47:2085–2095. https://doi.org/10.1016/J.WATRES.2013.01.033 CrossRefPubMedGoogle Scholar
- Freckman DW, Virginia RA (1997) Low-diversity antarctic soil nematode communities: distribution and response to disturbance. Ecology 78:363–369. https://doi.org/10.1890/0012-9658(1997)078[0363:LDASNC]2.0.CO;2 CrossRefGoogle Scholar
- Hughes WC (1980) Scour velocities in ephemeral channels. J Hydraul Div 106:1435–1441Google Scholar
- Magalhães C, Stevens MI, Cary SC, Ball BA, Storey BC, Wall DH, Türk R, Ruprecht U (2012) At limits of life: multidisciplinary insights reveal environmental constraints on biotic diversity in continental Antarctica. PLoS ONE 7:e44578. https://doi.org/10.1371/journal.pone.0044578 CrossRefPubMedPubMedCentralGoogle Scholar
- Majdi N, Mialet B, Boyer S, Tackx M, Leflaive J, Boulêtreau S, Ten-Hage L, Julien F, Fernandez R, Buffan-Dubau E (2012) The relationship between epilithic biofilm stability and its associated meiofauna under two patterns of flood disturbance. Freshw Sci 31:38–50. https://doi.org/10.1899/11-073.1 CrossRefGoogle Scholar
- McKnight DM, Tate CM, Andrews ED, Niyogi DK, Cozzetto K, Welch K, Lyons WB, Capone DG (2007) Reactivation of a cryptobiotic stream ecosystem in the McMurdo dry valleys, Antarctica: a long-term geomorphological experiment. Geomorphology 89:186–204. https://doi.org/10.1016/j.geomorph.2006.07.025 CrossRefGoogle Scholar
- Oksanen J, Blanchet FG, Kindt R, Legendre P, O’hara RB, Simpson GL, Solymos P, Stevens MH, Wagner H (2015) vegan: community ecology package. R package version 2-2Google Scholar
- Pinheiro J, Bates D, DebRoy S, Sarkar D (2014) nlme: linear and nonlinear mixed effects models. R package version 3.1-117Google Scholar
- R Core Team (2016) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Shaw EA, Adams BJ, Barrett JE, Lyons WB, Virginia RA, Wall DH (2018) Stable C and N isotope ratios reveal soil food web structure and identify the nematode Eudorylaimus antarcticus as an omnivore–predator in Taylor valley, Antarctica. Polar Biol. https://doi.org/10.1007/s00300-017-2243-8 Google Scholar
- Stanish LF, Kohler TJ, Esposito RM, Simmons BL, Nielsen UN, Wall DH, Nemergut DR, McKnight DM (2012) Extreme streams: flow intermittency as a control of diatom communities in meltwater streams in the McMurdo dry valleys, Antarctica. Can J Fish Aquat Sci 69:1420–1432. https://doi.org/10.1139/f2012-046 CrossRefGoogle Scholar
- Tytgat B, Verleyen E, Obbels D, Peeters K, De Wever A, D’hondt s (2014) Bacterial diversity assessment in antarctic terrestrial and aquatic microbial mats: a comparison between bidirectional pyrosequencing and cultivation. PLoS ONE 9:e97564. https://doi.org/10.1371/journal.pone.0097564 CrossRefPubMedPubMedCentralGoogle Scholar
- Vincent WF, Quesada A (2012) Cyanobacteria in high latitude lakes, rivers and seas. In: Ecology of cyanobacteria II: their diversity in space and timeGoogle Scholar