State of the Lake 2009 - Tahoe Environmental Research Center ...

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BIOLOGY TAHOE: STATE OF THE LAKE REPORT 2009 Algae groups as a fraction of total population Monthly in 2008 Algae populations vary month to month, as well as year to year. In 2008, diatoms again dominated the phytoplankton community, especially Biovolume (cubic millimeters per cubic meter) 250 200 150 100 50 0 in May-July when their biovolume was high. While the relative importance of the chlorophytes (green algae) increased in the fall, their biovolume Diatoms JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC 2008 Phycomycetes Cyanophytes Dinoflagellates did not peak as dramatically in 2008 as it did in 2007. Cryptophytes Chrysophytes Chlorophytes 10.7
BIOLOGY Nutrient limitation of algal growth In 2008 Bioassays determine the nutrient requirements of phytoplankton. Nutrients are added to lake water samples and algal biomass is measured. These tests document both seasonal and long-term changes in nutrient limitation. Phytoplankton response to nutrient addition for the period 2002-2008 Percent of experiments with increased algal growth 100% 80% 60% 40% 20% 0% TAHOE: STATE OF THE LAKE REPORT 2009 is shown in the panels below. Between January and April, algae were limited by phosphorus (P), not nitrogen (N), when added alone. When added together, stimulation nearly always occurred. From May to September, N added by itself was more stimulatory, but the lake was co-limited, as shown by the greater response to adding both nutrients. P was more stimulatory from October to December, but co-limitation was again the dominant condition. These results highlight the role of nutrients in controlling algal growth. They also underscore the synergistic effect when both are available. N P N+P N P N+P N P N+P Jan−Apr May−Sep Oct−Dec 10.8
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TAHOE: STATE OF THE LAKE REPORT 200
Page 3 and 4:
INTRODUCTION The University of Cali
Page 5 and 6: EXECUTIVE SUMMARY (CONTINUED FROM P
Page 7 and 8: ABOUT LAKE TAHOE AND THE TAHOE BASI
Page 9 and 10: MAP OF TAHOE BASIN DATA COLLECTION
Page 11 and 12: Rainbow, Brook, Brown and Lake trou
Page 13 and 14: 100% 90% 80% 70% 60% 50% 40% 30% 20
Page 15 and 16: ASIAN CLAM Asian Clam Excretion Exp
Page 17 and 18: ASIAN CLAM Asian Clam Size Distribu
Page 19 and 20: Temperature ( o F) 60 55 50 35 30 M
Page 21 and 22: Temperature ( o F) 70 60 50 40 30 2
Page 23 and 24: Inches 70 60 50 40 30 20 10 0 METEO
Page 25 and 26: Percent 80 70 60 50 40 30 20 10 0 M
Page 27 and 28: PHYSICAL PROPERTIES TERC.UCDAVIS.ED
Page 29 and 30: Feet 6232 6230 6228 6226 6224 6222
Page 31 and 32: Temperature ( o F) TERC.UCDAVIS.EDU
Page 33 and 34: Temperature ( o F) TERC.UCDAVIS.EDU
Page 35 and 36: Density Difference (kilograms per c
Page 37 and 38: Mean daily streamflow (cubic feet p
Page 39 and 40: NUTRIENTS AND PARTICLES TERC.UCDAVI
Page 41 and 42: TERC.UCDAVIS.EDU NUTRIENTS AND PART
Page 43 and 44: Metric Tons TERC.UCDAVIS.EDU 10 8 6
Page 45 and 46: Dissolved inorganic nitrogen (micro
Page 47 and 48: Nitrate−nitrogen (micrograms per
Page 49 and 50: BIOLOGY 10
Page 51 and 52: BIOLOGY Algae abundance Yearly sinc
Page 53 and 54: BIOLOGY Depth of chlorophyll maximu
Page 55: BIOLOGY TAHOE: STATE OF THE LAKE RE
Page 59 and 60: BIOLOGY Shoreline algae distributio
Page 61 and 62: TERC.UCDAVIS.EDU CLARITY Annual ave
Page 63 and 64: Depth (feet) TERC.UCDAVIS.EDU CLARI
Page 65: TERC.UCDAVIS.EDU OUTREACH AND EDUCA
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State of the Lake 2009 - Tahoe Environmental Research Center ...

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