McMurdo Dry Valley streams: Ecosystems Waiting for Water MCMLTER: PI-Lyons, Co-PI’s- Doran,...
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Transcript of McMurdo Dry Valley streams: Ecosystems Waiting for Water MCMLTER: PI-Lyons, Co-PI’s- Doran,...
![Page 1: McMurdo Dry Valley streams: Ecosystems Waiting for Water MCMLTER: PI-Lyons, Co-PI’s- Doran, Fountain, McKnight, Moorhead, Priscu,Virginia,Wall.](https://reader035.fdocuments.in/reader035/viewer/2022081601/56649f2a5503460f94c44d72/html5/thumbnails/1.jpg)
McMurdo Dry Valley streams: Ecosystems Waiting for Water
MCMLTER: PI-Lyons, Co-PI’s- Doran, Fountain, McKnight,
Moorhead, Priscu,Virginia,Wall
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McMurdo Dry Valleys, Antarctica
Polar desert: • Dry (<10 cm precip. Annually)• Cold (average air temp. = -20oC)
– Meltwater streams flow for 6 to 14 weeks– Streamflow is typically 0.01 to 5 cfs, stream
water temperature is typically 0.1 to 14 oC– Hyporheic zone is a key hydrologic feature– Habitat for benthic algae mats– Source and control of solute input to the lakes
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Glacial meltwater streams:climatic connection between the glaciers and the lakes
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Monitoring of streamflow and stream ecosystems
• Network of 19 stream gauges in Taylor and Wright Valleys-continuous (15 min)
• Collaboration between NSF and USGS
• Network of 18 transects to document ecological response to changing flow
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USGS hydrologist gauging Onyx River
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Creek
Canada Glacier
Commonwealth
Glacier
Crescent GlacierHoward
Glacier
Gre
en
Del
ta
Stre
amH
arnishStream
Von
GuerardStream
AikenCreek
Huey
Canada
Cre
ek
Stream
Stre amSeal
Lo
st
McK
nigh
t
Creek
Cre
sce n
tSt
reamN
2 km
RelictChannel
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MCMLTER gauging stations
• Challenge-range of flows and unstable substrate
• Parshall flumes with weirs in cutoff wall-compound rating
• Natural channel controls
• Located at outlets to lake
• Temporary sites near glaciers
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Parshall flume used to obtain accurate discharge at low flow
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Maintenance of gauges to maintain record
Green Creek gauge moveddue to lake level riseSanta Fe gauge pummeled by 100 cfs (cubic feet/sec)
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Fryxell basin: streamflow greater during 89-92 than during 93-present
0
100
200
300
400
500
600
90-91 91-92 92-93 93-94 94-95 95-96 96-97 97-98 98-99
Season
Vol
ume
(x10
6 m
3 )
CommonwealthLost SealHueyCanadaGreenAndersen
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Wright Valley: Onyx River flow has also been lower since 93
0
2000
4000
6000
8000
10000
12000
14000
90-91 91-92 92-93 93-94 94-95 95-96 96-97 97-98 98-99
Season
Vol
ume
(x10
6 m
3)
Onyx River at Vanda
Onyx River at Lower Wright
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Bonney basin: high streamflow from Taylor Glacier since 1993
0
200
400
600
800
1000
1200
90-91 91-92 92-93 93-94 94-95 95-96 96-97 97-98 98-99
Season
Vol
ume
(x10
6 m
3 )
Priscu
Lawson
Santa Fe
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Santa Fe Creek on 12/21/00: 35 cfs
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Filamentous cyanobacteria (blue-green algae): orange algal mats
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Black algal mats at stream edge: intermittent flow
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Orange algal mats in Von Guerard Stream:10-14 species in each sample
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Black algal mats in Von Guerard Stream:1-2 species in each sample
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Streams with stable habitat had few changes
Stream Habitat Mats 94-98
Canada Pavement abundant No change
Bowles Pavement abundant No change
Green Pavement abundant New green mats
Delta-upper
Pavement abundant New moss
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Some streams with poor habitat had more abundant mats
Stream Habitat Mats 94-98
Huey Sandy sparse More orange new black
Delta-g Sandy sparse New orange
VonG-g Sandy sparse More mats!
Lawson Steep sparse More orange & moss
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Hyporheic zone: under and adjacent to stream with active exchange of water
PermafrostPermafrost
Permafrost
Active Layer
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In dry valley streams the “hyporheic zone” is observed as a wetted zone adjacent to stream
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Dry valley streams flow through porous alluvium with high rates of “hyporheic exchange”.
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In cold summers, glacial meltwater soaks in and sublimates in fall and winter.
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Stream scale experiments to quantify biogeochemical processes
• Short term experimental perturbations to quantify nutrient uptake and hydrology
• Long term experiment studying ecological response to geomorphological evolution of stream networks
• Experiments reviewed through environmental assessment process
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Experimental enrichment with nitrate and phosphate: 1.5 hrs
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Sampling Green Creek during experiment
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Stream algal mats win! Added nutrients are taken up and do not reach the lake.
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In cold summers, streams retain water and nutrients, lakes fend for themselves.
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Stream channel that had been inactive was “reactivated” by directing water to channel
with low sandbag wall
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Algal mats in reactivated relict channel are most productive mats is Taylor Valley
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Photosynthesis measured as rate of oxygen production by mat samples
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Higher nutrients in relict channel water enhances growth
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An axiom of ecology is: “Where there is water, there is life.” In Dry Valleys: “Where there has been and will be water, there is life.”
Dry valley stream ecosystems can withstand cold, desiccation annually and for longer periods, as long as decades or centuries.
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The Stream Team gratefully acknowledgeslogistical support provided by PHI, ASA and Raytheon, and field assistance from other MCMLTER investigators