%0 Journal Article %J Biological Reviews %D 2021 %T Antarctic ecosystems in transition – life between stresses and opportunities %A Gutt, Julian %A Isla, Enrique %A Xavier, José C. %A Adams, Byron J. %A Ahn, In‐Young %A Cheng, C.‐H. Christina %A Colesie, Claudia %A Cummings, Vonda J. %A di Prisco, Guido %A Griffiths, Huw J. %A Ian Hawes %A Hogg, Ian D. %A McIntyre, Trevor %A Meiners, Klaus M. %A Pearce, David A. %A Lloyd S. Peck %A Piepenburg, Dieter %A Reisinger, Ryan R. %A Saba, Grace %A Schloss, Irene R. %A Signori, Camila N. %A Smith, Craig R. %A Vacchi, Marino %A Verde, Cinzia %A Diana H. Wall %K adaptation %K benthic dynamism %K biogeochemical cycles %K climate change %K invasion %K new habitats %K ocean acidification %K Primary production %K range shifts %K sea ice %X

Important findings from the second decade of the 21st century on the impact of environmental change on biological processes in the Antarctic were synthesised by 26 international experts. Ten key messages emerged that have stakeholder‐relevance and/or a high impact for the scientific community. They address (i) altered biogeochemical cycles, (ii) ocean acidification, (iii) climate change hotspots, (iv) unexpected dynamism in seabed‐dwelling populations, (v) spatial range shifts, (vi) adaptation and thermal resilience, (vii) sea ice related biological fluctuations, (viii) pollution, (ix) endangered terrestrial endemism and (x) the discovery of unknown habitats. Most Antarctic biotas are exposed to multiple stresses and considered vulnerable to environmental change due to narrow tolerance ranges, rapid change, projected circumpolar impacts, low potential for timely genetic adaptation, and migration barriers. Important ecosystem functions, such as primary production and energy transfer between trophic levels, have already changed, and biodiversity patterns have shifted. A confidence assessment of the degree of ‘scientific understanding’ revealed an intermediate level for most of the more detailed sub‐messages, indicating that process‐oriented research has been successful in the past decade. Additional efforts are necessary, however, to achieve the level of robustness in scientific knowledge that is required to inform protection measures of the unique Antarctic terrestrial and marine ecosystems, and their contributions to global biodiversity and ecosystem services.

%B Biological Reviews %8 06/2021 %G eng %U https://onlinelibrary.wiley.com/doi/full/10.1111/brv.12679 %R 10.1111/brv.12679 %0 Journal Article %J Polar Biology %D 2017 %T Impact of nitrogen and phosphorus on phytoplankton production and bacterial community structure in two stratified Antarctic lakes: a bioassay approach %A Teufel, Amber G. %A Li, Wei %A Kiss, Andor J. %A Rachael M. Morgan-Kiss %K Algal–bacteria interactions %K climate change %K McMurdo Dry Valleys %K Nutrient bioassay %K Primary production %X

Arctic, Antarctic, and alpine ecosystems are recognized as sensors and sentinels of global change. As a consequence of their high sensitivity to minor climatic perturbations, permanently ice-covered lakes located in the McMurdo Dry Valleys (MDV), Antarctica, represent end members in the global network of inland bodies of water. Episodic climatic events in the form of increased summer glacial melt result in inputs of organic sediment and nutrients from glacial streams to these closed basins. Phytoplankton communities residing in the oligotrophic water columns are highly responsive to pulses in nutrient availability; however, there is a lack of understanding on whether specific phytoplankton groups are more competitive during a summer flood event and how shifts in the phytoplankton community may influence heterotrophic bacteria. A bioassay approach in 3-l bottles was used to investigate the influence of inorganic nitrogen and phosphorus availability on planktonic communities from the oligotrophic upper waters of two chemically distinct MDV lakes (Lakes Bonney and Fryxell) which differ in their external inputs and water column N/P stoichiometry. While microbial community responses varied between lakes and were nutrient-dependent, stimulation of phytoplankton biomass and productivity across all treatments was strongly linked with increased abundance of a single phytoplankton phylum (Chlorophyta). Despite stimulation of phytoplankton growth, primary and bacterial productivity was generally uncoupled; however, shifts in bacterial community diversity were observed in bioassays amended with either P or NP. We suggest that climate-associated increases in phytoplankton production and concomitant shifts in diversity will influence MDV bacterial community structure by altering the availability and composition of autochthonous carbon for heterotrophic production.

%B Polar Biology %V 40 %8 05/2017 %G eng %U https://link.springer.com/article/10.1007/s00300-016-2025-8 %N 5 %! Polar Biol %& 1007 %R 10.1007/s00300-016-2025-8 %0 Thesis %B Department of Microbiology %D 2016 %T Influence of abiotic drivers (light and nutrients) on photobiology and diversity of Antarctic lake phytoplankton communities %A Teufel, Amber G. %A Rachael M. Morgan-Kiss %K Antarctica %K bacterial production %K Chlamydomonas sp ICE MDV %K Chlorophyll fluorescence %K circadian rhythm %K climate change %K McMurdo Dry Valleys %K nutrient amendment %K photobiology %K Primary production %X

Arctic, Antarctic, and alpine ecosystems are recognized as sensors and sentinels of global climate change. As a consequence of their high sensitivity to minor climatic perturbations, permanently ice-covered lakes located in the McMurdo Dry Valleys (MCM), Antarctica, represent end members in the global network of inland bodies of water. Episodic climatic events in the form of increased summer glacial melt result in inputs of organic sediment and nutrients from glacial streams to these closed basins. By better understanding how Antarctic lake communities respond to mimicked climate change, we can more accurately predict how they will react to further temperature changes in the future. We began by investigating the influence of inorganic nitrogen and phosphorus availability on planktonic communities residing in the oligotrophic upper waters of two chemically distinct MCM lakes (Lakes Bonney and Fryxell) which differ in their external inputs as well as water column N:P stoichiometry. Although microbial community responses varied between the lakes and were nutrient-dependent, stimulation of phytoplankton biomass and productivity across all treatments was strongly linked with increased abundance of a single phytoplankton phylum (Chlorophyta). Despite stimulation of phytoplankton growth, primary and bacterial productivity were largely uncoupled across all enrichments. We suggest that climate-associated shifts in phytoplankton diversity influence the bacterial community structure by altering the availability and composition of autochthonous carbon for heterotrophic production. To monitor the physiological adaptations that occur over time and depth, we then transplanted two dominant phytoplankton, Chlamydomonas sp. ICE- MDV and Isochrysis sp. MDV back into the Lake Bonney water column. Our results demonstrated that both organisms are specialists for surviving specific depths of the water column and are capable of acclimating to their native environment within a short period of time, and that the chlorophyte Chlamydomonas sp. ICE-MDV most likely makes this adjustment via photoacclimation and accumulating chlorophyll-a per cell. The final study presented here investigated whether or not the dominant chlorophyte, Chlamydomonas sp. ICE-MDV has retained the ability to respond to a diel 12-hour day/night cycle. Although light levels in MCM lakes remain low during the austral summers, daily irradiation varies by as much as tenfold during the course of the day, resulting in a circadian-like light cycle for organisms residing there. With decreased ice coverage on the lakes due to climate change and increased melt, it is likely that these light variations will become amplified over time. This study tested for the presence of a circadian rhythm under various light quality, light quantity, and temperature conditions and demonstrated that although a diel rhythm was maintained in terms of growth and several photochemical parameters, a true circadian rhythm was not identified. Although it is predicted that photosynthetic communities in polar regions will be more responsive to climate warming and episodic events, the complexity of these systems provides numerous challenges to understanding how these organism will adapt in the future.

%B Department of Microbiology %I Miami University %C Oxford, OH %V Ph.D. %8 2016 %G eng %U http://rave.ohiolink.edu/etdc/view?acc_num=miami1468411564 %9 doctoral