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Seasonal Changes in Plankton Food Web Structure and Carbon Dioxide Flux from Southern California Reservoirs.

Adamczyk EM, Shurin JB - PLoS ONE (2015)

Bottom Line: We sampled three reservoirs in San Diego, California, weekly for one year.We found that San Diego reservoirs are most often undersaturated with CO2 with respect to the atmosphere and are estimated to absorb on average 3.22 mmol C m(-2) day(-1). pCO2 was highest in the winter and lower in the summer, indicating seasonal shifts in the magnitudes of photosynthesis and respiration associated with day length, temperature and water inputs.Our data indicate that reservoirs of semi-arid environments may primarily function as carbon sinks, and that carbon flux varies seasonally but is unrelated to nutrient or DOC availability, or the abundances of phytoplankton or zooplankton.

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Sciences, Section of Ecology, Behavior and Evolution, University of California San Diego, La Jolla, California, United States of America.

ABSTRACT
Reservoirs around the world contribute to cycling of carbon dioxide (CO2) with the atmosphere, but there is little information on how ecosystem processes determine the absorption or emission of CO2. Reservoirs are the most prevalent freshwater systems in the arid southwest of North America, yet it is unclear whether they sequester or release CO2 and therefore how water impoundment impacts global carbon cycling. We sampled three reservoirs in San Diego, California, weekly for one year. We measured seasonal variation in the abundances of bacteria, phytoplankton, and zooplankton, as well as water chemistry (pH, nutrients, ions, dissolved organic carbon [DOC]), which were used to estimate partial pressure of CO2 (pCO2), and CO2 flux. We found that San Diego reservoirs are most often undersaturated with CO2 with respect to the atmosphere and are estimated to absorb on average 3.22 mmol C m(-2) day(-1). pCO2 was highest in the winter and lower in the summer, indicating seasonal shifts in the magnitudes of photosynthesis and respiration associated with day length, temperature and water inputs. Abundances of microbes (bacteria) peaked in the winter along with pCO2, while phytoplankton, nutrients, zooplankton and DOC were all unrelated to pCO2. Our data indicate that reservoirs of semi-arid environments may primarily function as carbon sinks, and that carbon flux varies seasonally but is unrelated to nutrient or DOC availability, or the abundances of phytoplankton or zooplankton.

No MeSH data available.


Surface (1 m) and bottom (16–20 m) water temperatures (°C) for each reservoir from Sept 2013-June 2014.The bottom depths for Lakes Poway and Miramar was 20 m and the bottom depth for Lake Murray was 16–17 m. The water columns are stratified when the lines diverge and mixed when the surface and bottom temperatures are the same.
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pone.0140464.g009: Surface (1 m) and bottom (16–20 m) water temperatures (°C) for each reservoir from Sept 2013-June 2014.The bottom depths for Lakes Poway and Miramar was 20 m and the bottom depth for Lake Murray was 16–17 m. The water columns are stratified when the lines diverge and mixed when the surface and bottom temperatures are the same.

Mentions: The water columns for Lakes Murray and Miramar were found to be stratified throughout the summer with thermocline depths at 13 m and 19 m respectively, and were not stratified between Oct 2013-Feb 2014 (Fig 9). Lake Poway’s water column was mixed from Sept 2013-Feb 2014 and then remained stratified thereafter with a thermocline depth at 13 m. For all reservoirs, surface water temperatures decreased by about 10°C from summer to winter.


Seasonal Changes in Plankton Food Web Structure and Carbon Dioxide Flux from Southern California Reservoirs.

Adamczyk EM, Shurin JB - PLoS ONE (2015)

Surface (1 m) and bottom (16–20 m) water temperatures (°C) for each reservoir from Sept 2013-June 2014.The bottom depths for Lakes Poway and Miramar was 20 m and the bottom depth for Lake Murray was 16–17 m. The water columns are stratified when the lines diverge and mixed when the surface and bottom temperatures are the same.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4608793&req=5

pone.0140464.g009: Surface (1 m) and bottom (16–20 m) water temperatures (°C) for each reservoir from Sept 2013-June 2014.The bottom depths for Lakes Poway and Miramar was 20 m and the bottom depth for Lake Murray was 16–17 m. The water columns are stratified when the lines diverge and mixed when the surface and bottom temperatures are the same.
Mentions: The water columns for Lakes Murray and Miramar were found to be stratified throughout the summer with thermocline depths at 13 m and 19 m respectively, and were not stratified between Oct 2013-Feb 2014 (Fig 9). Lake Poway’s water column was mixed from Sept 2013-Feb 2014 and then remained stratified thereafter with a thermocline depth at 13 m. For all reservoirs, surface water temperatures decreased by about 10°C from summer to winter.

Bottom Line: We sampled three reservoirs in San Diego, California, weekly for one year.We found that San Diego reservoirs are most often undersaturated with CO2 with respect to the atmosphere and are estimated to absorb on average 3.22 mmol C m(-2) day(-1). pCO2 was highest in the winter and lower in the summer, indicating seasonal shifts in the magnitudes of photosynthesis and respiration associated with day length, temperature and water inputs.Our data indicate that reservoirs of semi-arid environments may primarily function as carbon sinks, and that carbon flux varies seasonally but is unrelated to nutrient or DOC availability, or the abundances of phytoplankton or zooplankton.

View Article: PubMed Central - PubMed

Affiliation: Division of Biological Sciences, Section of Ecology, Behavior and Evolution, University of California San Diego, La Jolla, California, United States of America.

ABSTRACT
Reservoirs around the world contribute to cycling of carbon dioxide (CO2) with the atmosphere, but there is little information on how ecosystem processes determine the absorption or emission of CO2. Reservoirs are the most prevalent freshwater systems in the arid southwest of North America, yet it is unclear whether they sequester or release CO2 and therefore how water impoundment impacts global carbon cycling. We sampled three reservoirs in San Diego, California, weekly for one year. We measured seasonal variation in the abundances of bacteria, phytoplankton, and zooplankton, as well as water chemistry (pH, nutrients, ions, dissolved organic carbon [DOC]), which were used to estimate partial pressure of CO2 (pCO2), and CO2 flux. We found that San Diego reservoirs are most often undersaturated with CO2 with respect to the atmosphere and are estimated to absorb on average 3.22 mmol C m(-2) day(-1). pCO2 was highest in the winter and lower in the summer, indicating seasonal shifts in the magnitudes of photosynthesis and respiration associated with day length, temperature and water inputs. Abundances of microbes (bacteria) peaked in the winter along with pCO2, while phytoplankton, nutrients, zooplankton and DOC were all unrelated to pCO2. Our data indicate that reservoirs of semi-arid environments may primarily function as carbon sinks, and that carbon flux varies seasonally but is unrelated to nutrient or DOC availability, or the abundances of phytoplankton or zooplankton.

No MeSH data available.