Figure S7. photos of marine-brackish diatoms and some fragments. (a) Cyclotella stylorum ; (b) Actinoptychus undulatus ; (c) Diploneis smithii var.dilatata ; (d)Arcocellulus cornucervis ; (e) Nitzschia granulata ; (f)Melosira sulcata var. sulcata ; (g) Coscinodiscus asteromphalus var. asteromphalus ); (h) photos of diatom fragments, abundant in U4.