TY - JOUR
T1 - Dna damage and photosynthetic inhibition induced by solar ultraviolet radiation in tropical phytoplankton (lake titicaca, bolivia)
AU - Helbling, E. Walter
AU - Villafañe, Virginia
AU - Buma, Anita
AU - Andrade Flores, Marcos Foilán
AU - Zaratti Sachetti, Francesco
PY - 2001/5/1
Y1 - 2001/5/1
N2 - Experiments were conducted during October 1998 in Lake Titicaca, Bolivia (16° S, 68° W, 3810 m a.s.l), to determine the effects of solar ultraviolet radiation (UVR) on phytoplankton photosynthetic rates and DNA damage. Water samples were taken daily and incubated in situ or in simulated in situ conditions using sharp cut-off filters to eliminate various portions of the UVR spectrum. The total inhibition of photosynthesis due to UVR in surface waters was 85%; the greatest part of this inhibition (65%) was due to UVAR (315–400 nm), the rest (20%) being due to UVBR (280–315 nm). The inhibition of photosynthesis decreased with depth so that there were no significant differences among treatments at 1.3 optical depths (KPAR). The loss of carbon assimilation in the integrated production over the euphotic zone (4.6 optical depths) was 17.4%, with 14% due to UVAR and an additional 3.4% due to UVBR. Lake Titicaca phytoplankton had a reshold for inhibition of photosynthesis at about 0.3 W m−2 for UVBR and 5 W m−2 for UVAR, below which no inhibition was detected. Above this threshold, photosynthetic inhibition increased steadily, with UVAR having the greatest effect. Analysis of biological weighting functions (BWFs) indicated that phytoplankton from Lake Titicaca was less sensitive to UVR than phytoplankton from other regions. DNA damage (evaluated through the formation of cyclobutane pyrimidine dimers, CPDs) was observed for a simulated worst-case situation (i.e. samples incubated in full sunlight) and significant CPD accumulation was found as a result of UVBR exposure, but not with UVAR. However, absolute levels of damage were relatively low when compared with results obtained at other locations, also suggesting the low sensitivity of Lake Titicaca phytoplankton to UVR. It seems that UVBR stress in these organisms acts via at least two cellular targets: the photosynthetic apparatus and nuclear DNA. Our results suggest that an eventual enhancement of UVBR, due to ozone depletion, would have little impact on the phytoplankton of Lake Titicaca.
AB - Experiments were conducted during October 1998 in Lake Titicaca, Bolivia (16° S, 68° W, 3810 m a.s.l), to determine the effects of solar ultraviolet radiation (UVR) on phytoplankton photosynthetic rates and DNA damage. Water samples were taken daily and incubated in situ or in simulated in situ conditions using sharp cut-off filters to eliminate various portions of the UVR spectrum. The total inhibition of photosynthesis due to UVR in surface waters was 85%; the greatest part of this inhibition (65%) was due to UVAR (315–400 nm), the rest (20%) being due to UVBR (280–315 nm). The inhibition of photosynthesis decreased with depth so that there were no significant differences among treatments at 1.3 optical depths (KPAR). The loss of carbon assimilation in the integrated production over the euphotic zone (4.6 optical depths) was 17.4%, with 14% due to UVAR and an additional 3.4% due to UVBR. Lake Titicaca phytoplankton had a reshold for inhibition of photosynthesis at about 0.3 W m−2 for UVBR and 5 W m−2 for UVAR, below which no inhibition was detected. Above this threshold, photosynthetic inhibition increased steadily, with UVAR having the greatest effect. Analysis of biological weighting functions (BWFs) indicated that phytoplankton from Lake Titicaca was less sensitive to UVR than phytoplankton from other regions. DNA damage (evaluated through the formation of cyclobutane pyrimidine dimers, CPDs) was observed for a simulated worst-case situation (i.e. samples incubated in full sunlight) and significant CPD accumulation was found as a result of UVBR exposure, but not with UVAR. However, absolute levels of damage were relatively low when compared with results obtained at other locations, also suggesting the low sensitivity of Lake Titicaca phytoplankton to UVR. It seems that UVBR stress in these organisms acts via at least two cellular targets: the photosynthetic apparatus and nuclear DNA. Our results suggest that an eventual enhancement of UVBR, due to ozone depletion, would have little impact on the phytoplankton of Lake Titicaca.
KW - Cyclobutane pyrimidine dimers
KW - DNA damage
KW - Lake Titicaca
KW - Photosynthesis
KW - Phytoplankton
KW - Ultraviolet radiation
UR - http://www.scopus.com/inward/record.url?scp=85024216619&partnerID=8YFLogxK
U2 - 10.1080/09670260110001735308
DO - 10.1080/09670260110001735308
M3 - Artículo
AN - SCOPUS:85024216619
VL - 36
SP - 157
EP - 166
JO - British Phycological Journal
JF - British Phycological Journal
SN - 0967-0262
IS - 2
ER -