Variasi Temporal Kadar Saksitoksin dalam Kekerangan dari Perairan Tanjung Balai, Sumatra Utara

Abstract

Kekerangan merupakan salah satu biota ekonomi penting di sektor perikanan. Namun, dengan sifatnya sebagai filter feeder, pencemaran lingkungan perairan dapat mempengaruhi keamanan pangannya, misalnya pencemaran senyawa saksitoksin, yang sering terakumulasi di biota kekerangan. Saksitoksin adalah senyawa yang dihasilkan oleh fitoplakton perairan, sehingga kadarnya dapat bervariasi secara temporal. Penelitian ini bertujuan untuk mengetahui variasi temporal  secara musiman (muson timur, peralihan, dan barat) dari kadar saksitoksin pada tiga jenis biota kerang ekonomis (Anadara granosa, Anadara antiquata, dan Polymesoda erosa) yang diperoleh dari Perairan Tanjung Balai. Kekerangan diketahui sebagai produk unggulan di sentra perikanan Tanjung Balai. Variasi temporal kadar saksitoksin dihubungkan dengan kualitas air, untuk mengetahui korelasinya terhadap lingkungan tempat hidup kekerangan. Kualitas air dianalisis secara in situ menggunakan metode potensiometri dan kolorimetri, sementara kuantifikasi saksitoksin dilakukan menggunakan teknik spektrometri massa. Hasil analisis memperlihatkan bahwa kadar saksitoksin dari ketiga jenis kerang bervariasi antara 0,04 hingga 0,16 mg STXeq/kg berat basah kerang. Hal ini menunjukkan kekerangan di wilayah ini aman dari bahaya saksitoksin (ambang maksimum 0,8 mg STXeq/kg). Kadar bahan berbahaya ini tidak secara signifikan (P>0,05) dipengaruhi oleh ukuran dan jenis kerang. Namun, akumulasinya di musim muson barat secara signifikan (P<0,05) lebih tinggi dibandingkan dengan musim muson timur dan peralihan. Hal ini diduga terkait dengan musim penghujan di muson barat yang meningkatkan polusi nutrien akibat limpasan terestrial. Kondisi ini diduga memicu peningkatan pertumbuhan fitoplakton, termasuk jenis penghasil saksitoksin, sehingga memicu peningkatan akumulasinya di kekerangan.

Temporal Variation of Saxitoxin Content in Mussels from Tanjung Balai Waters, North Sumatra

Abstract

Marine mussels are  important economic resources in fisheries sector. However, due to their filter feeder characteristic, environmental water pollution may affect their safety as food. For example, saxitoxin is one of dangerous chemical substances that usually accumulate in marine mussels. This substance is produced by phytoplankton; thus, the temporal content of saxitoxin in mussel may vary. This research aimed to analyze the temporal variations (east, intermediate, and west monsoon seasons) of saxitoxin from three economical marine mussels (Anadara granosa, Anadara antiquata, dan Polymesoda erosa) that were taken from Tanjung Balai Waters, Indonesia. Mussels are known as the most important fisheries product from this region. Temporal variation of saxitoxin was correlated to water quality, to analyze the relationship between saxitoxin accumulation with marine mussel environment. Water quality was analyzed in situ by potentiometric and colorimetric, while saxitoxin concentration was quantified by mass spectroscopic method. Results of this study showed that saxitoxin was found at 0.04 to 0.16 mg/kg wet weight of the sample. Thus, it may consider as safe, as the safety level of saxitoxin is recommended at below 0.8 mg/kg. The level of saxitoxin was not found to be significantly (P>0.05) different between the size and the type of the mussels. However, saxitoxin from mussels that were collected during west monsoon season was significantly (P<0.05) higher than those collected during east and intermediate seasons. It is  suggested that the rainy season which coincides with the west monsoon season in Indonesia, may increase the terrestrial run-off that contains nutrient pollutants. This condition may alter the composition of phytoplankton, including the saxitoxin producing phytoplankton, thus increase the accumulation of saxitoxin in mussels.