Browsing by Author "Tanjung, Afrizal"

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    The Collection Pharella Acutidens (Broderip & Sowerby, 1828) Smaller Than 20 Mm As An Indication For The Time Of Spat Settlement In The Mangrove Forest Of The Riau University, Dumai
    (2016-04-02) Tanjung, Afrizal
    Five years field observation, Januari 2006 – December 2010, were carried out to document the presence of Pharella acutidens (Broderip & Sowerby 1828) smaller than 20 mm in the mangrove forest of the Riau University Marine Station, Dumai. It was done in order to describe the seasonally of spat settlement. The purposive sampling technik was used in this work. The psycochemical parameters of its habitat were also monitored every month. Not every month of the year the bivalve smaller than 20 mm was presence, but only from Agustus until November at the year. It was found at special substrate at the habitat where the waters was contained more than 4,2 mgl-1 disolve oxygen, pH arround 7, salinity 8,5- 20,5 ppt. It is supposed that the spat settle on substrate from Februari until Mei every year.
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    Factors Influencing the Distribution of Bivalve at Intertidal Zone of The Sungai Nipah, The Pesisir Selatan Regency, West Sumatera
    (2016-03-30) Elizal; Tanjung, Afrizal
    This study has been done in March 2013. It aimed to find out the factors that have influenced on the distribution of bivalves in the intertidal zone of Sungai Nipah bay. The purposive sampling method was used to choose three stations at the intertidal zones of the bay.The occurrences of bivalves and the frequencies of disturbanceswere recorded. Other parameters on the sites were also measured either in the field or in the lab. As a result, there were 21 species found in the area understudy. Other findings were: 1) the further the sites from the coast line, the more abundance the animals were, 2) opposite to the organic content in the sandy substrate, the increase of both current speed and disturbances, had shown influence on the decrease of abundance; although there was no different distribution pattern between the stations observed. Other parameters on the habitats showed there were no influence on the abundance and the distribution pattern
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    The Indication of Gastropods Extinction at Intertidal Zone of The Teluk Nipah Waters, The Pesisir Selatan Regency The Province of The West Sumatera
    (2016-03-22) Tanjung, Afrizal
    Intensive observation on gastropods, every Mart from the year of 2008 to the year of 2012, was carried out to document some indicators of gastropods extinction. The purposive sampling technik was used in this work. The psycochemical parameters of its habitat were also monitored every sampling done. It was found that the intertidal zone substrate consists of sand, while the habitat parameters were more than 5,6 mgl-1 disolved oxygen, pH arround 7,0–7,2 salinity 30,2 -32,2 ppt, temperature 28,6-29,60C, the visibility 100%. The number of species, the number of found gastropods, the abundance, the maximum shell size of found gastropods showed decreasing from year to year; while routine collecting by the visitor and marine organisms shell collector, and disturbance by the fisherman activities were occured. This indication showed a tendency of gastropods extinction.