zulkarnaen, Ibnu2013-07-232013-07-232013-07-23sumarnihttp://repository.unri.ac.id:80/handle/123456789/4618This research has aims to know Estuary fecundity zoom Rokan's River is sighted from nitrate concentration, phosphate, and profusion at diatom and relationship among concentrates nitrate, phosphate with profusion at diatom.the research was performed on 16th June 2012 at River Estuary waters Rokan, Sinaboy's district Rokan's regency Riau's province Downstream. These result points out that nitrate concentration on basic station sampling at 0,027 0,032 mg / L. Meanwhile phosphate concentration on each ranging station 0,875 – 0,916 mg / L. base on the research station is found 27 specieses at diatom, species at diatom that often emerges at each station is Skeletonema Costatum. This species gets character euryhaline andeurythermal. Concentration nitrate the River Estuary waters Rokan categorised lush reducing waters (oligotropik)meanwhile for phosphate concentration comprises (mesotropik). According to subjective research result nitrate concentration with profusion at diatom while blows over to be gotten can r =0,84 and while assemble to be can r=0,34. Meanwhile for relationship among phosphate concentration with profusion at diatom upon subsiding being gottencan r=0,58 and at the moment tide are gotten assesses canr=0,25 subjective matternitrate concentration with profusion at diatom upon subsiding categorised strong and at the moment rank tide rans down meanwhile for phosphate concentration with profusion at diatom upon subsiding categorised be and at the moment rank tide rans down.otherNitratePhospateDiatomProfusionEstuary of Rokan riverstudent Paper Post Degree