title: Diuron causes sinking retardation and physiochemical alteration in marine diatoms Thalassiosira pseudonana and Skeletonema marinoi-dohrnii complex.
abstract: The present research investigated the effect of diuron on sinking rate and the physiochemical changes in two marine diatoms, Thalassiosira pseudonana (single-celled species) and Skeletonema marinoi-dohrnii complex (chain-forming species). The results revealed that the sinking rate of both diatoms exposed to diuron at a level of 50% effective concentration for growth (EC50) decreased significantly compared with the control. Photosynthetic performance (Fv/Fm and PIABS) of both diatoms also decreased significantly with diuron exposure. The number of cells per chain in S. marinoi-dohrnii decreased significantly with diuron treatment, but T. pseudonana cell diameter remained stable. Neutral lipid concentration per cell was significantly higher compared with control at 72 h in both diatom species exposed to EC50 level diuron. And water-soluble protein concentration per cell at 72 h was lower than control in the T. pseudonana EC50 group only. These biochemical changes may decrease specific gravity of cells and seems to cause a decreased sinking rate in diatoms. The positive significant correlation between the numbers of cells per chain and sinking rate in S. marinoi-dohrnii indicated that chain length is also an important factor in sinking rate regulation for chain-forming diatoms. Thus, our present study suggested that suppression of photosynthetic performance and the resultant physiochemical changes induced the decreased sinking rate that may inhibit the normal survival strategy (avoidance from the surface layer where strong light either causes photo-inhibition or interrupts resting cell formation). Therefore, the use of antifouling agents should be considered for the sustainable marine environment.
authors.affiliation: Laboratory of Marine Environmental Science, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Mst Ruhina Margia
authors.initials: MRM
authors.lastname: Khanam
authors.affiliation: Laboratory of Marine Environmental Science, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan. Electronic address: simasaki@agr.kyushu-u.ac.jp.
authors.forename: Yohei
authors.initials: Y
authors.lastname: Shimasaki
authors.affiliation: Graduate School of Systems Life Sciences, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan.
authors.forename: Md Zahangir
authors.initials: MZ
authors.lastname: Hosain
authors.affiliation: Laboratory of Marine Environmental Science, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Koki
authors.initials: K
authors.lastname: Mukai
authors.affiliation: Laboratory of Silviculture, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Michito
authors.initials: M
authors.lastname: Tsuyama
authors.affiliation: Laboratory of Marine Environmental Science, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Xuchun
authors.initials: X
authors.lastname: Qiu
authors.affiliation: Laboratory of Marine Environmental Science, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan; Department of Zoology, Faculty of Life and Earth Sciences, Jagannath University, Dhaka 1100, Bangladesh.
authors.forename: Rumana
authors.initials: R
authors.lastname: Tasmin
authors.affiliation: Laboratory of Marine Environmental Science, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Goto
authors.affiliation: Laboratory of Marine Environmental Science, Faculty of Agriculture, Kyushu University, 6-10-1 Hakozaki, Higashi-ku, Fukuoka, 812-8581, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Oshima
mesh_terms: D017377:Diatoms / Q000187:drug effects* / Q000502:physiology; D004237:Diuron / Q000633:toxicity*; D006540:Herbicides / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D006540:Herbicides; D014874:Water Pollutants, Chemical; D004237:Diuron
keywords: Diatoms; Diuron; Sinking rate; Skeletonema marinoi-dohrnii complex; Thalassiosira pseudonana