No abstract

The characteristics, distribution, and accumulation of detrital sediment on the surface sediment in the Senunu Sea are used as a preliminary study to identify the detrital and sedimentation processes’ origin. This study aims to present the characters and composition of detrital sediment on Senunu seabed. It illustrates the influence of land sediment sources on sediment compositions settled on the bottom of the surrounding seas. Specific review on the sediment character in this region was done to identify surface sediment layers carrying tailings materials from ore mining on land and differentiate them from natural sediment. 53 sediment core from the Senunu bottom were collected and analyzed for their detrital characteristics using a binocular microscope. In general, sediment composition in Senunu seabed was terrigenous sediment with dominant material quartz, andesite, and tuffaceous breccia. Based on the detrital analysis, sediment lithology of natural seabed sediment and sediment containing tailing material is distinguished by color, layer contact, grain packing, grain shape, biota association, and specific mineral content quartz, mica, and magnetite. Surface sediment containing tailing material had more quartz mineral, had more similar grain size and crystal shape, fresher mineral condition, clearer color, and looser grain relation than seabed sediment that did not contain tailings material.. Based on the different characters and distribution patterns, sediment carrying tailings in the Senunu seabed. Based on the other characters and distribution patterns, sediments carrying tailings in the Senunu seabed on average were 2-167 centimeter thick at the surface with accumulated tailing 1-50% of total sediment at the sea bottom. Furthermore, the distribution of these tailing deposits is influenced mainly by morphodynamic, hydrodynamic conditions and the process of redeposition.

Characteristics of coastal tidal areas of Batu (1) seagrass (21.3%) in the upper zone (high tide), (2) algae (35.5%) in the central zone (mid tide), and (3) coral (28.5%) and algae (42.5%) in the lower zone (low tide). The main groups of biota in the form of tidal zoning system consisting of two groups of molluscs (51.12%) in the upper zone, while the echinoderms that predominate in the central zone (36.96%) and lower (66.89%). No significant differences between the structure and composition of marine intertidal communities in September 2011 (rainy season) and April 2012 (dry season).Keywords: intertidal (tidal), percent cover, density, community, biota ABSTRAK Karakteristik daerah pasang surut pesisir Batu Hijau bervariasi mulai dari tipe substrat berpasir, karang berpasir hingga berbatu dengan lebar hamparan intertidal berkisar dari 100 meter hingga 350 meter. Untuk mengetahui zonasi komunitas intertidal dilakukan pengamatan biota intertidal pada lima lokasi pantai intertidal yang masing-masing terdiri dari tiga zona yaitu pasang tinggi, pasang tengah dan pasang rendah. Struktur kehidupan di daerah pasang surut, pesisir Batu Hijau, Sumbawa terdiri dari komunitas utama dan biota yang berasosiasi. Komunitas utama intertidal terdiri dari karang, lamun, alga dan fauna lainnya, sedangkan biota intertidal yang berasosiasi dengan habitat pasang surut terdiri dari kelompok moluska, ekhinodermata, krustase, cacing dan ikan. Sebaran komunitas intertidal membentuk tiga zona yang terdiri dari (1) lamun (21,3%) di zona atas (pasang tinggi), (2) alga (35,5%) di zona tengah (pasang sedang), dan (3) karang (28,5 %) dan alga (42,5%) di zona bawah (pasang rendah). Kelompok biota utama di daerah pasang surut membentuk sistem dua zonasi yang terdiri dari kelompok moluska (51,12%) pada zona atas, sedangkan kelompok ekhinodermata yang mendominasi di zona tengah (36,96%) dan bawah (66,89%). Tidak ada perbedaan yang signifikan antara struktur komunitas dan komposisi biota intertidal pada September 2011 (musim hujan) dan April 2012 (musim kemarau).Kata kunci: intertidal (pasang surut), persen tutupan, kepadatan, komunitas, biota

Newly released current velocity and temperature measurements in the Alas Strait collected from November 2005 to February 2007 permit calculation of the mean and variable transport of the Indonesian Throughflow (ITF) in this region. These data were collected by the Environmental Division of the Amman Mineral Nusa Tenggara mining company to serve as a guide for the deep submarine placement of tailings produced by the Batu Hijau open pit copper-gold mine. Ocean currents, temperatures, and winds in the Alas Strait region exhibit intraseasonal and seasonal variability, with modulation at interannual timescales that may be associated with intraseasonal Kelvin waves, the regional southeast monsoon, the El Niño Southern Oscillation, and the Indian Ocean Dipole (IOD). Currents in the Alas Strait were found to flow steadily southward not only during the boreal summer from mid-April to October but also when a prolonged anomalously easterly wind associated with positive IOD extended this flow direction through the end of December 2006. A steady shear between the northward-flowing upper layer and the southward-flowing layer beneath was recorded from November 2005 to early April 2006 and from January to February 2007. The 2006 annual transport was –0.25 Sv toward the Indian Ocean and varied from 0.4 Sv in early April 2006 to –0.75 Sv in August 2006. Hence, Alas Strait transport plays a dual role in the total ITF, increasing it during boreal summer and reducing it during boreal winter. Northward flows tend to carry warmer water from the Indian Ocean to the Flores Sea, while the southward ITF flow carries cooler water to the Indian Ocean. Although the Alas Strait is located next to the Lombok Strait—one of the major ITF exit passages—they have different current and temperature characteristics. For a more complete evaluation of the ITF, the Alas Strait must be included in any future monitoring.

Characteristics of coastal tidal areas of Batu Hijau vary from sandy substrate type, sandy to rocky reef with a wide expanse of intertidal ranges from 100 meters to 350 meters. To find out zoning intertidal community,the observation conducted at five locations intertidal beach, each consisting of three zones: the high tide, middle tide and low tide. Living structure in tidal areas of coastal Batu Hijau, Sumbawa consists of the main communities and associated biota. The main intertidal community composed of coral, seagrass, algae, and other fauna, while the intertidal biota associated with tidal habitat consists of a group of molluscs, echinoderm, crustacean, worms and fish. Distribution of intertidal communities formed three zones consisting of (1) seagrass (21.3%) in the upper zone (high tide), (2) algae (35.5%) in the central zone (mid tide), and (3) coral (28.5%) and algae (42.5%) in the lower zone (low tide). The main groups of biota in the form of tidal zoning system consisting of two groups of molluscs (51.12%) in the upper zone, while the echinoderms that predominate in the central zone (36.96%) and lower (66.89%). No significant differences between the structure and composition of marine intertidal communities in September 2011 (rainy season) and April 2012 (dry season). Keywords: intertidal (tidal), percent cover, density, community, biota