The research was aimed to analyzed ecologically feasibility and prospective of Pacific white shrimp (Litopenaeus vannamei) cultivation in Rokan Hilir Regency and City of Dumai. The sudy was conducted from January 2017 to April 2018 in 5 sub-districts; Sungai Sembilan (City of Dumai), Sinaboi, Rimba Melintang, Bangko and Batu Hampar (Rokan Hilir District), Riau Province, Indonesia. Water samples were collected at the Senepis River, Nyamuk River, Sinaboi River, Teluk Dalam River, RKT plot and Camp Pemda in the Diamond Raya Timber concession area. It was noted; pH (5.22-7.0), salinity (5.0 to 22.5), phosphate (0.4-1.263 mg/L), ammonia (0.03-0.352 mg/L), nitrate (0.346-0.379 mg/L), CO2 (15.980-123.685 mg/L) DO (2.7-5.7 mg/L) COD (70.4-114.4 mg/L), BOD (4.85-6.4 mg/L) and number of Coliform bacterial cells (7.0-233.05 cfu/100 ml). The dominant species of fish caught in river waters are common species, as in zooplankton, phytoplankton, benthos, and manngrove community. Based on species data, abundancy index, diversity index, homogenity index and dominance index shows that the waters are still in normal condition. The study conclude the area is still in normal condition and suitable for Pacific white shrimp cultivation.

The Malacca Strait is the importance waters for international shipping routes and more 200 cases of ship collisions in the period 1970-2015 in this strait. That is related to some a shallow depth waters with many small islands and strong current which is making this strait have a highest risk in certain seasons. The CMEMS data used to understanding of mechanism of current, illustrate the pattern and tranport volume. The research uses descriptive and the statistical methods to understanding of mechanism and variability of current. The analysis of current patterns and water level shows that during the monsoon winds active, the current always moves to the Andaman Sea, we called the southeast current system. The Northeast (NE) and Southwest (SW) monsoon wind is strongly influence to the mechanism of formation southeast current system, which causes the varition in sea level hight in eastern and western of Malacca Strait. During the NE monsoon season, the water masses of the South China Sea are push away into the Karimata Strait, causing the sea level in the eastern part to be higher than the western part and will increase the current speed. On the other hand, during the SW monsoon season, the water masses from the Karimata Strait is pushed away from the eastern part of the Malacca Strait which causes the sea level decrease and causes the current speed to weaken. Numbers eddies phenomenon were found at the Malacca Strait each season. The anticyclonic eddies occurred almost every season centered at 3° - 5° N, 97° - 100° E. Meanwhile anticyclonic eddies appear around the northern part of Sumatra centered at 4° - 5°N, 99° - 101°E during SW Monsoon season and the eddies formation also existed during the second transition monsoon season.

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