ABSTRAK
Penelitian mengenai struktur komunitas Gastropoda dan mangrove sudah dilakukan di Kawasan PLTU Karimun, Pulau Karimun Besar, Kepulauan Riau pada Mei 2016. Penelitian bertujuan untuk dapat mengetahui struktur komunitas Gastropoda dan mangrove di area pesisir kawasan PLTU Karimun, Pulau Karimun Besar. Selain itu juga, menganalis hubungan santara kerapatan mangrove dengan kepadatan Gastropoda pada area tersebut. Pengambilan sampel Gastropoda dilakukan di setiap stasiun pengamatan dengan metode purposive random sampling bersamaan dengan pengamatan ekosistem mangrove menggunakan metode garis berpetak. Petak 1 x 1 m ditaruh pada setiap petak 10 x 10 m di stasiun-stasiun pengamatan. Hasil penelitian diperoleh 8 jenis Gastropoda dan 8 jenis mangrove. Keanekaragaman jenis Gastropoda dan mangrove di area penelitian termasuk kategori yang tinggi dengan indeks keanekaragaman 2,04 dan 1,98. Kemerataan jenis mangrove di area penelitian tergolong kategori yang hampir merata dengan indeks 0,95. Kemerataan jenis Gastropoda di area penelitian tergolong kategori merata dengan indeks 0,98. Tingkat kesamaan jenis Mangrove dan Gatropoda tertinggi terdapat pada stasiun 1 dan 3. Terdapat hubungan antara kerapatan mangrove dengan kepadatan Gastropoda di Kawasan PLTU Karimun. Hal tersebut didukung dengan adanya korelasi positif yang didapat dengan menggunakan uji Spearmann pada software SPSS 16 (R = 0,829).

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ABSTRAK
A study about communnity structure of Gastropods and Mangrove at PLTU Karimun?s area, Pulau Karimun Besar, Kepulauan Riau has been conducted on May 2016. The objectives of the study were aimed to determine the community structure of Gastropods and mangroves at PLTU Karimun?s coastal area. And also, to analyze a correlation between closeness of mangrove species and density of Gastropods. Sample of Gastropods were collected in three stations using purposive random sampling method with mangroves ecosystem obeservation using quadrate transect method. 1 x 1 m quadrate for Gastropods were put on each 10 x 10 m quadrate for mangroves observation. The results showed 8 species Gastropods and 8 species of mangroves. Species diversity for Gastropods (H? = 2,04) and Mangroves (H? = 1,98) in three stations is categorized as high ranged. The evenness of Mangroves (e = 0,95) is classified into almost evenly. The evenness of Gastropods (e = 0,98) is classified as evenly. The highest similarity index for Mangroves and Gastropods was found in station 1 and 3. There is a correlation between closeness of mangroves and density of Gastropods at PLTU Karimun?s area. It was supported with positive correlation obtained by using Spearmann test with SPSS 16 software (R = 0,829)