Community metabolism in a deep (stratified) tropical reservoir during a period of high water-level fluctuations
Por:
Valdespino-Castillo, PM, Merino-Ibarra, M, Jimenez-Contreras, J, Castillo-Sandoval, FS, Ramirez-Zierold, JA
Publicada:
1 oct 2014
Resumen:
As long as lakes and reservoirs are an important component of the global
carbon cycle, monitoring of their metabolism is required, especially in
the tropics. In particular, the response of deep reservoirs to
water-level fluctuations (WLF) is an understudied field. Here, we study
community metabolism through oxygen dynamics in a deep monomictic
reservoir where high WLF (similar to 10 m) have recently occurred.
Simultaneous monitoring of environmental variables and zooplankton
dynamics was used to assess the effects of WLF on the metabolism of the
eutrophic Valle de Bravo (VB) reservoir, where cyanobacteria blooms are
frequent. Mean gross primary production (P (g)) was high (2.2 g C m(-2)
day(-1)), but temporal variation of P (g) was low except for a drastic
reduction during circulation attributed to zooplankton grazing. The
trophogenic layer showed net autotrophy on an annual basis, but turned
to net heterotrophy during mixing, and furthermore when the whole
water-column oxygen balance was calculated, considering the aphotic
respiration (R (aphotic)). The high total respiration resulting (3.1 g C
m(-2) day(-1)) is considered to be partly due to mixing enhanced by WLF.
Net ecosystem production was equivalent to a net export of 3.4 mg CO2
m(-2) day(-1) to the atmosphere. Low water levels are posed to intensify
boundary-mixing events driven by the wind during the stratification in
VB. Long-term monitoring showed changes in the planktonic community and
a strong silicon decrease that matched with low water-level periods. The
effects of low water-level on metabolism and planktonic community in VB
suggest that water-level manipulation could be a useful management tool
to promote phytoplankton groups other than cyanobacteria.
Filiaciones:
Valdespino-Castillo, PM:
Univ Nacl Autonoma Mexico, Posgrad Ciencias Mar & Limnol, Mexico City 04510, DF, Mexico
Merino-Ibarra, M:
Univ Nacl Autonoma Mexico, Unidad Acad Ecol & Biodiversidad Acuat, Inst Ciencias Mar & Limnol, Mexico City 04510, DF, Mexico
Jimenez-Contreras, J:
Univ Nacl Autonoma Mexico, Posgrad Ciencias Mar & Limnol, Mexico City 04510, DF, Mexico
Castillo-Sandoval, FS:
Univ Nacl Autonoma Mexico, Unidad Acad Ecol & Biodiversidad Acuat, Inst Ciencias Mar & Limnol, Mexico City 04510, DF, Mexico
Ramirez-Zierold, JA:
Univ Nacl Autonoma Mexico, Posgrad Ciencias Mar & Limnol, Mexico City 04510, DF, Mexico
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