TBT toxicity on a natural planktonic assemblage exposed to enhanced ultraviolet-B radiation

SARGIAN, P., É. PELLETIER, B. MOSTAJIR, G.A. FERREYRA AND S. DEMERS

AQUATIC TOXICOLOGY

Elsevier

Año: 2005 vol. 73 p. 299 - 314

0166-445X

Amicrocosm approachwas designed to study the combined effects of tributyltin (TBT) from antifouling paints and ultraviolet- B radiation (UVBR: 280–320 nm), on a natural planktonic assemblage (<150
m) isolated from the St. Lawrence Estuary at the end of the springtime. Microcosms (9 l, cylindrical Teflon® bags, 75 cm height×25 cm width) were immersed in thewater column of mesocosms (1800 l, polyethylene bags, 2.3m depth) and exposed to two different UVBR regimes: natural ambient UVBR (NUVBR), and enhanced level of UVBR (HUVBR). During consecutive 5 days, effects of TBT (120 ng l−1) and enhanced UVBR (giving a biologically weighted UVBR 2.15-fold higher than natural light condition) were monitored in the samples coming from following treatments: (i) NUVBR light condition without TBT (NUVBR), (ii) NUVBR light condition with TBTadded (NUVBR + TBT), (iii) HUVBR light condition without TBT (HUVBR) and (iv) HUVBR light condition with TBT-added (HUVBR + TBT). Each treatment was conducted in triplicate microcosms. Different parameters were then measured during 5 days, including TBT analysis, bacterial abundance and productivity, phytoplankton abundance, cellular characteristics and growth rates, as well as in vivo chlorophyll a (Chl a) fluorescence. Following TBT addition (NUVBR + TBT treatment), Chl a
m) isolated from the St. Lawrence Estuary at the end of the springtime. Microcosms (9 l, cylindrical Teflon® bags, 75 cm height×25 cm width) were immersed in thewater column of mesocosms (1800 l, polyethylene bags, 2.3m depth) and exposed to two different UVBR regimes: natural ambient UVBR (NUVBR), and enhanced level of UVBR (HUVBR). During consecutive 5 days, effects of TBT (120 ng l−1) and enhanced UVBR (giving a biologically weighted UVBR 2.15-fold higher than natural light condition) were monitored in the samples coming from following treatments: (i) NUVBR light condition without TBT (NUVBR), (ii) NUVBR light condition with TBTadded (NUVBR + TBT), (iii) HUVBR light condition without TBT (HUVBR) and (iv) HUVBR light condition with TBT-added (HUVBR + TBT). Each treatment was conducted in triplicate microcosms. Different parameters were then measured during 5 days, including TBT analysis, bacterial abundance and productivity, phytoplankton abundance, cellular characteristics and growth rates, as well as in vivo chlorophyll a (Chl a) fluorescence. Following TBT addition (NUVBR + TBT treatment), Chl a® bags, 75 cm height×25 cm width) were immersed in thewater column of mesocosms (1800 l, polyethylene bags, 2.3m depth) and exposed to two different UVBR regimes: natural ambient UVBR (NUVBR), and enhanced level of UVBR (HUVBR). During consecutive 5 days, effects of TBT (120 ng l−1) and enhanced UVBR (giving a biologically weighted UVBR 2.15-fold higher than natural light condition) were monitored in the samples coming from following treatments: (i) NUVBR light condition without TBT (NUVBR), (ii) NUVBR light condition with TBTadded (NUVBR + TBT), (iii) HUVBR light condition without TBT (HUVBR) and (iv) HUVBR light condition with TBT-added (HUVBR + TBT). Each treatment was conducted in triplicate microcosms. Different parameters were then measured during 5 days, including TBT analysis, bacterial abundance and productivity, phytoplankton abundance, cellular characteristics and growth rates, as well as in vivo chlorophyll a (Chl a) fluorescence. Following TBT addition (NUVBR + TBT treatment), Chl a−1) and enhanced UVBR (giving a biologically weighted UVBR 2.15-fold higher than natural light condition) were monitored in the samples coming from following treatments: (i) NUVBR light condition without TBT (NUVBR), (ii) NUVBR light condition with TBTadded (NUVBR + TBT), (iii) HUVBR light condition without TBT (HUVBR) and (iv) HUVBR light condition with TBT-added (HUVBR + TBT). Each treatment was conducted in triplicate microcosms. Different parameters were then measured during 5 days, including TBT analysis, bacterial abundance and productivity, phytoplankton abundance, cellular characteristics and growth rates, as well as in vivo chlorophyll a (Chl a) fluorescence. Following TBT addition (NUVBR + TBT treatment), Chl aa (Chl a) fluorescence. Following TBT addition (NUVBR + TBT treatment), Chl a concentrations never exceeded 1
g l−1 whereas final values as high as 54
g l−1 were observed in TBT-free treatments (NUVBR and HUVBR). TBT addition resulted also in the lost of fluorescence signal of the maximum efficiency of the photosystem II in phytoplankton assemblage. TBT toxicity caused on phytoplankton <20
m an increase of mean cell size and changes in shape reflected a drastic disturbance of the cell cycle leading to an inhibition of the apparent growth rate. These negative effects of TBT resulted in a final abundance of phytoplankton <20
m of 591±35 cells ml−1 in NUVBR+ TBT relative to NUVBR
g l−1 whereas final values as high as 54
g l−1 were observed in TBT-free treatments (NUVBR and HUVBR). TBT addition resulted also in the lost of fluorescence signal of the maximum efficiency of the photosystem II in phytoplankton assemblage. TBT toxicity caused on phytoplankton <20
m an increase of mean cell size and changes in shape reflected a drastic disturbance of the cell cycle leading to an inhibition of the apparent growth rate. These negative effects of TBT resulted in a final abundance of phytoplankton <20
m of 591±35 cells ml−1 in NUVBR+ TBT relative to NUVBR
m an increase of mean cell size and changes in shape reflected a drastic disturbance of the cell cycle leading to an inhibition of the apparent growth rate. These negative effects of TBT resulted in a final abundance of phytoplankton <20
m of 591±35 cells ml−1 in NUVBR+ TBT relative to NUVBR
m of 591±35 cells ml−1 in NUVBR+ TBT relative to NUVBR