Effect of bentazon on growth and physiological responses of marine diatom: Chaetoceros gracilis.
The herbicide bentazon (CASRN 25057-89-0) is extensively used in agriculture in Brittany (France) to replace atrazine. Bentazon is not readily adsorbed by soil and therefore it enters adjacent freshwater ecosystems, making its way to estuarine and marine waters areas. Information regarding its effects on marine ecosystems is scarce. Phytotoxicity assessments were conducted in the laboratory on the common diatom Chaetoceros gracilis using both the active ingredient and its formulated product (Basamaïs). The 3 day EC(50) using cell counts were, respectively, 150 mg/L and 60 microg/L for bentazon active ingredient and for bentazon-formulated while cellular volume was increased. Although bentazon is known as a photosystem II inhibitor, it produced an increase of pigment (chlorophylls a, c, and carotenoids) content, ATP synthesis, rates of photosynthesis and respiration, and TBARS formation. Therefore, pigments cannot be used as biomarkers of toxicity. Algal cell recovery from bentazon effects occurred after 6-9 days, suggesting a tolerance mechanism.
Laboratory of Biotechnology and Plant Physiology, UFR Sciences et Techniques, Brest, France. annick.hourmant@univ-brest.fr
Annick
A
Hourmant
Anis
A
Amara
Patrick
P
Pouline
Gaël
G
Durand
Geneviève
G
Arzul
Françoise
F
Quiniou
D000255:Adenosine Triphosphate / Q000378:metabolism; D001581:Benzothiadiazines / Q000494:pharmacology*; D002338:Carotenoids / Q000378:metabolism; D019069:Cell Respiration / Q000187:drug effects; D002734:Chlorophyll / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D017377:Diatoms / Q000187:drug effects / Q000254:growth & development; D006540:Herbicides / Q000494:pharmacology*; D015227:Lipid Peroxidation; D010788:Photosynthesis / Q000187:drug effects; D045332:Photosystem II Protein Complex / Q000378:metabolism; D012623:Seawater; D017392:Thiobarbituric Acid Reactive Substances / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000494:pharmacology
D001581:Benzothiadiazines; D003470:Culture Media; D006540:Herbicides; D045332:Photosystem II Protein Complex; D017392:Thiobarbituric Acid Reactive Substances; D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D002338:Carotenoids; D000255:Adenosine Triphosphate; C002003:bentazone