Salinity responses of benthic diatoms inhabiting tidal flats

Abstract

We performed culture experiments using intertidal benthic diatoms collected from a river mouth tidal flat (Fujimae Tidal Flats, Nagoya, Japan) to study their responses to salinity. The six species examined were Navicula aff. erifuga, Karayevia amoena, Tryblionella apiculata, Planothidium delicatulum, Melosira moniliformis var. octogona, and Entomoneis japonica. Clones were grown at ten salinity levels from 0 to 50 psu. Three species were unable to grow at low salinities (0 and 0.1 psu), but all were able to grow, though at a reduced rate, in hypersaline conditions (50 psu). All species had wider tolerance ranges than the salinity range of their original habitat (4–16 psu). Two species, T. apiculata and K. amoena, were essentially euryhaline, while the other four showed various constraints on their salinity response. Two species, P. delicatulum and M. moniliformis var. octogona, showed optimal growth outside the range of the salinities normally occurring in the environment from which they were isolated.

Keywords:

• benthic diatoms
• culture experiment
• growth rate
• river mouth intertidal flats
• salinity gradient

Acknowledgements

We thank Dr Taisuke Ohtsuka, Lake Biwa Museum, for his invaluable help in identifying the diatom species, and for insightful advice. We also thank Dr Koshi Yamamoto (Nagoya Univ.) for his assistance in analyses using ion chromatography, Dr Ituki Suto (Nagoya Univ.) for the use of the scanning electron microscope, and Dr Kenichiro Sugitani (Nagoya Univ.) for his help with the English manuscript. The members of the Save Fujimae Association, who saved Fujimae Tidal Flats from becoming a garbage/landfill project and who worked to achieve the Ramsar Convention List designation are greatly acknowledged. They were always helpful to our sampling and use of their facilities. Finally, but not least, we are sincerely grateful to the reviewers and editors for their useful comments and suggestions.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental data

Supplemental data for this article can be accessed at 10.1080/0269249X.2017.1366951