Struktur komunitas fitoplankton dan kaitannya dengan ketersediaan zat hara dan parameter kualitas air lainnya di perairan Timur Surabaya

Abstract. The objetives of the present research were to determine relationship of phytoplankton abundance and community structure with environmental factors.The research was conducted in twelve stations along East Surabaya’s Coastal Waters. The samplings were represented early dry season (May-July 2013). Regression Correlation Analisis and Principle Component Analysis were involved to determine the relationship between community structure of phytoplankton and nutrient availability as well as other environmental parameters. The results showed that the concentration of Nitrate (NO3-N) was ranged from 1.80mg/L to 7.31 mg/L while Phosphate (PO4-P) was 0.20 – 4.75 mg/L. The phytoplankton abundance was varied between 3300 cell/L to 47000 cell/L. The highest phytoplankton abundance was found in the estuary and deacreased toward the sea areas. The dDiversity and evennes indices were low category, while dominance index was found to be relatively high, where Skeletonema sp. was predominant. Diversity index was not correlated significantly with nutrient availability, while there were a significant correlation between phytoplankton abundance and environment parameters namely salinity, DO and brighnessKeywords : phytoplankton abundance; oseanography factor; spatial analysis; coastal watersAbstrak. Penelitian ini bertujuan untuk mengetahui keterkaitan antara kelimpahann dan struktur komunitas fitoplankton dengan faktor lingkungan di perairan pesisir. Penelitian dilakukan pada 12 stasiun berbeda di Perairan Timur Surabaya. Sampling plankton dan kualitas air mewakili awal musim kemarau (Mei – Juli 2013). Analisis regresi korelasi dan analisis komponen utama dilakukan untuk melihat keterkaitan struktur komunitas dan ketersedian zat hara dan parameter lingkungan lainnya di lokasi penelitian. Hasil penelitian menunjukkan kandungan zat hara yang relatif tinggi: Nitrat (NO3-N) antara 1,80 – 7,31 mg/L dan Fosfat (PO4-P) antara 0,20 – 4,75 mg/L. Distribusi fitoplankton bervariasi antara 3,3 – 4,7.103sel/L. Kelimpahan plankton paling tinggi didapat pada stasiun muara sungai dengan indikasi penurunan ke arah laut. Indeks keragaman jenis (H’) dan indeks keseragaman jenis (E) relatif rendah; sebaliknya indeks dominasi tinggi (D0,5) dengan didominasi oleh Skeletonema sp.. Indeks diversitas menunjukkan hubungan yang tidak bermakna dengan zat hara. Namun, kelimpahan fitoplankton berkorelasi secara signifikan dengan parameter salinitas, DO dan kecerahan.Kata kunci :kelimpahan fitoplankton; faktor oseanografi; analisis spasial; perairan pesisi