Semarang is one of the main transportation crossing along the North coast of Java, which is very vulnerable to environmental damage. One of the damage is the beach abrasion that threaten in several point di Semarang coastal area. To overcome this problem then build  the construction of wave retaining buildings such as breakwater. Breakwater will reduce the rate of abrasion, because breakwater can break waves dan make its power reduced before it reaches the shoreline, so that the rate of abrasion can be compressed.Breakwater slowly will affect to the ecosystem by its sedimentation because of the  material accumulation and the become solidified. From this sediment will become a habitat to several organism. This research  was held from December 2016 - January 2017 at Semarang coastal area that divided into two station which is Station 1 at Mangkang area (West Semarang) and station 2 at Tambak Lorok area (North Semarang). The purpose of this research is to see the habitat of the organism that lived in sedimentation area around  the breakwater. The organism which is the object of research is macrozoobenthos. Macrozoobenthos is made an object of the research because of the nature of these organism whose lives are settled at the bottom of the coastal. The method used in this research is descriptive comparative. Based on research of the study makrozoobenthos has been found in each station from several classes . Polychaeta is a genus that dominates at every location because muddy sand is its main habitat.

552 grain size samples and 33 mineral quality defined samples have been collected in the Co To island, Tonkin Bay of Vietnam, to study the distribution and the sediment provenance. The field investigation method, the grain analysis, and the detrital composition examination method have been used to study the characteristics of the surface sediments in Co To island. The obtained results show that the surface sediments in the area consist of ten different fields, namely: sandy gravel, gravelly sand, sand, gravelly muddy sand, sand mixed gravel, muddy sand, gravelly mud mixed sand, silty sand, muddy sandy gravel, and sandy mud. The mineral component method shows that quartz is the main contain of the surface sediment (72,0÷90,6%), less rock detritus, felspat, mica, and very few of the shells. It is to confirm that the continent is the main primary material source of the study area. The distribution of the sediment is complicated. As the East-Southeast side of the research area, the sediment distribution following gravity way, coarse grain near the shore (gravel, sandy gravel,…), finer grain far off the shore (gravelly muddy sand, silty sand,…), choice level is very low. Which This is saying that the movement of sediment in the area is dominant, ; the flow energy is governed by the topography near the island and seafloor. In tMhe meanwhile, the west-northwest side, the topography of seafloor is the complicated, coarse sediment grains (gravel, sand), ); the roundness is bad, which is saying that the hydrodynamic flow there plays an important role in the sediment distribution.

The location of the Fenced Lagoon in the urban basin of Bandar Anzali, which should be considered due to its impact on the lives of the people of the region in terms of the conservation of the wetland and its environmental issues, and, on the other hand, the potential of this area to be introduced as a geotourism center determine the need to investigate the area’s sedimentology and geochemistry. Therefore, to study sedimentary and geochemical properties of the Fenced Lagoon sediments located in Bandar Anzali, 33 samples were taken in the form of 6 cores and 12 grabs, and basic sedimentation tests and heavy metals measurement were carried out on them .Studies show that the sediments range from sand to clay in terms of gradation and have mainly coastal-river origin. The sediments of this lake are classified into four sedimentary types: Muddy Sand, Slightly Gravelly Muddy Sand, Sand and Slightly Gravelly Sand, and sand is the main component of all of these sediments. The most abundant sedimentary types belong to Muddy Sand and Sand and the least abundant sedimentary types belong to Slightly Gravelly Muddy Sand and Slightly Gravely Sand. The nature of the source rock is derived from acidic to intermediate combination and in general, sedimentary rocks of the area under study are within the continental arch islands and, to a lesser extent, the active continental margin.

Hybrid event beds and a debrite are identified in a core on the mid-shelf of East China Sea. Four units are divided according to abrupt boundary identification, with assistance of grain size analysis. The hybrid event beds typically comprise four internal divisions from the base to the top: (1) structureless muddy sand (H1a, high density turbidite); (2) massive muddy sand with mud clasts (H1b, higher density turbidite); (3) linked debrite (H3); (4) homogeneous mud (H5, fluid mud). The radiocarbon ages of the core were in the range of 3890–8526 yr BP. Based on correlation with other surrounding cores, the depositional age of hybrid event beds and the debrite may be less than 500 yr BP. The TOC and δ¹³C values in event beds suggest a local erosional regime. The average δ¹³C value for turbidite (H1a and H1b) is similar to the H3 division in the hybrid event beds, implying that the organic matter in the H1a, H1b and H3 may come from the same source area. The REE data reveals the sediment source is initially from Korean rivers. Bi-plots of (La/Lu)_UCC vs. (La/Y)_UCC, (La/Y)_UCC vs. (Gd/Lu)_UCC, (La/Yb)_UCC vs. (Gd/Yb)_UCC and (La/Yb)_UCC vs. (Sm/Nd)_UCC of four units in the core are concentrated in the similar range, indicating these event beds have the same source area. Both regimes that partial transformation from a debris flow and erosional bulking are suggested. It is unlikely that the debris flow is triggered by a hyperpycnal flow or a tsunami, because both can carry continental and/or coastal signals which have not been recognized in the core. Typhoon can be a probable triggering mechanism.

Acknowledgements

This paper was supported by National Program on Global Change and Air-Sea Interaction (Grant No. GASI-GEOGE-03), National Natural Science Foundation of China (Grants No U1606401 and No. 41706063) and the Taishan Scholar Program of Shandong.

Seagrass ecosystem is one of shallow sea ecosystems that plays an important role to maintain stability of the sea. Density and coverage of seagrass depend on characteristic of sediment, include mean size and the type of sediment. The purpose of this study was to find out how density and coverage of seagrass on different type of sediment at Pandaratan Beach Tapanuli Tengah Regency North Sumatera Province. This research was conducted in April 2019. From the results can be discovered that there are two species of seagrass that found in Pandaratan Beach, Cymodocea rotundata and Enhalus acoroides. In the type of muddy sand sediment has the heighest density of seagrass which is 309 ind/m2 and categorized into very tight. In the type of sandy gravel sediment has the lowest density of seagrass which is 49 ind/m2 and categorized into very rare. And in the type of gravely sand sediment has the density of seagrass that is 234 ind/m2 and categorized into very tight. In the type of muddy sand sediment has the heighest coverage of seagrass which is 50.18% and categorized into good. In the type of sandy gravel sediment has the lowest coverage which is 17.72%. And in the type of gravely sand sediment has the coverage of seagrass which is 26.95% and categorize into moderately.

Abstract. Research on analysis of sediments chemistry around the mangrove ecosystem of Lambadeuk village, Peukan Bada Subdistrict aimed to the analyze nutrient content of sediments around mangrove ecosystem which grows in Lambadeuk, Aceh Besar. The study was conducted in April 2018 - May 2019. Research stations were determined by using purposive random sampling method then sediment samples were taken by coring technic. The results of the analysis showed that there are two types of sediments; muddy sand and sandy mud type of sediment. Sandy mud sediment has higher organic matter than muddy sand. The percentage value of total organic matters ranged from 27.89% - 42.41%, while C-Organic was between 0.08% - 1.28%. The percentage of dominant C-organic was found in places that are overgrown with mangroves, while the total organic matter content is more in places that does not have mangroves. In addition to the presence of mangroves that affect the amount of organic sediment and type of sediment, oceanographic factors such as currents, topography, organic matter content, and C-Organic are also affect the type of existing sediment.Keywords: Mangroves, Sediment, Organic matter, C-Organic.Abstrak. Penelitian mengenai analisis kimia sedimen di sekitar ekosistem mangrove Desa Lambadeuk, Kecamatan Peukan Bada bertujuan untuk menganalisis kandungan unsur hara sedimen di sekitar ekosistem mangrove yang tumbuh di daerah Lambadeuk, Aceh Besar. Penelitian ini dilakukan pada bulan April – Mei 2019. Metode penentuan stasiun penelitian menggunakan metode purposive random sampling kemudian sampel sedimen diambil dengan menggunakan coring. Hasil analisis menunjukkan bahwa tipe sedimen yang ada di Desa Lambadeuk, Kecamatan Peukan Bada terdapat dua tipe sedimen yaitu pasir berlumpur (muddy sand) dan lumpur berpasir (sandy mud). Tipe sedimen lumpur berpasir memiliki kandungan bahan organik lebih tinggi daripada pasir berlumpur. Nilai persentase kandungan bahan organik total berkisar yaitu berkisar antara 27,89 % - 42,41 %, sedangkan C-organik berkisar antara 0,08 % - 1,28 %. Persentase C-organik lebih banyak terdapat di tempat yang banyak ditumbuhi mangrove, sedangkan kandungan bahan organik total lebih banyak di tempat yang tidak ditumbuhi mangrove sama sekali. Disamping keberadaan mangrove yang mempengaruhi besarnya bahan organic sedimen, faktor-faktor oseanografi seperti arus, topografi, kandungan bahan organik, dan C-organik juga mempengauhi tipe sedimen yang ada.Kata Kunci: Mangrove, Sedimen, Bahan Organik, C-organik. 

Представлены сведения об обнаружении в зал. Петра Великого (северо-западная часть Японского моря) нового для фауны России вида двустворчатого моллюска Tellimya fujitaniana (Yokoyama, 1927) (Lasaeidae). Три живые особи с длиной раковины 3.9–6.2 мм собраны в 2003 и 2018 гг. в диапазоне глубин 17–28 м на илисто-песчаном грунте. Обобщены данные по экологии и ареалу данного вида. Ключевые слова: двустворчатый моллюск, Tellimya fujitaniana (Yokoyama, 1927), Lasaeidae, распространение, залив Петра Великого, Японское море. Information on finding in Peter the Great Bay (north-western part of the Sea of Japan) a new species of bivalve mollusk for the fauna of Russia, Tellimya fujitaniana (Yokoyama, 1927) (Lasaeidae), are presented. Three alive specimens with shell length 3.9–6.2 мм were collected in 2003 and 2018 at the depths of 17–28 m on muddy sand. Data on the ecology and geographical range of this species are summarized. Key words: bivalve mollusks, Tellimya fujitaniana (Yokoyama, 1927), Lasaeidae, distribution, Peter the Great Bay, Sea of Japan.

The location of the Fenced Lagoon in the urban basin of Bandar Anzali, which should be considered due to its impact on the lives of the people of the region in terms of the conservation of the wetland and its environmental issues, and, on the other hand, the potential of this area to be introduced as a geotourism center determine the need to investigate the area's sedimentology and geochemistry. Therefore, to study sedimentary and geochemical properties of the Fenced Lagoon sediments located in Bandar Anzali, 33 samples were taken in the form of 6 cores and 12 grabs, andbasic sedimentation tests and heavy metals measurement were carried out through XRF. Studies show that the sediments are ranged from sand to clay in terms of gradation and have mainly costal-river origin. The sediments of this lake are classified into four sedimentary types: Muddy Sand, Slightly Gravely Muddy Sand, Sand and Slightly Gravely Sand and sand is the main component of all of these sediments. The most abundant sedimentary types belong to Muddy Sand and Sand and the least abundant sedimentary types belong to Slightly Gravely Muddy Sand and Slightly Gravely Sand. The nature of the source rock is derived from acidic to intermediate combination and in general, sedimentary rocks of the area under study are within the continental arch islands and, to a lesser extent, the active continental margin.

Relations between economic zoobenthos species and ecological characteristics of Thi Nai lagoon were reported as results of three surveys carried out during 2014–2015. The results have pointed out 11 zoobenthos species that have primarily economic value at the Thi Nai lagoon (5 bivalve species, 5 crustacea species and 1 gastropoda species). Bivalve group possesses 91% of the entire commercial yield of benthic animal (7,456.9 tons/year), in which Glauconome chinensis and Gari elongata possess dominatingly (possess 90% of the entire commercial yield of bivalves: 6,817 tons/year). Bivalve and gastropoda groups were found in correlation with sandy sediment and mangroves but crustacea group was found in correlation with muddy sand sediments and seagrass. The results of this study will conntribute the scientific basis for further studies on the trophic relationship, food web and data for planning, zoning and appropriate exploitation of fisheries resources.

Characteristic of Dog Conch (Strombus turturella) Habitat on The Seagrass Ecosystem  Strombus turturella or commonly known as dog conch is one of marine shellfish which has important ecological role, as well as high economical value as fisheries commodity. The objectives of the study were to determine the density and biomass of the shellfish, as well as to observe the distribution pattern and the characteristics of dog conch habitat in the seagrass ecosystem. The research was conducted at Tukak Island and Anak Air Island, Bangka Belitung Islands. Density of the shellfish, seagrass coverage, seagrass density as well as water chemistry and physical parameters, while data collection in laboratory, measurement of dog conch biomass, substrate texture test and organic matter content. Habitat characteristics were determined using principal component analysis (PCA), which connects between dog conch  density variables, seagrass vegetation and chemical physics parameters. The average density of dog conch in all locations is 2312 ind / ha. The pattern of distribution of dog conch at the study site there is a pattern of uniform distribution and clumping, but the overall pattern of distribution is clustering. The PCA results show dog conch, with habitat characteristics that is very low seagrass cover (1-5%), overgrown species of Halophila minor seagrass, with the condition of muddy sand substrate and low content of organic matter. Result of the correlation matrix dog conch was correlated with H. Minor seagrass (0.88), very low seagrass cover (0.86) and muddy sand substrate (0.9). This is aimed at dog conch keeping specific microhabitat in the seagrass ecosystem.  Siput gonggong memiliki peranan ekologis yang penting di habitatnya. Nilai ekonomis siput gonggong yang tinggi sebagai komoditas perikanan telah menyebabkan eksploitasi berlebihan terhadap spesies tersebut. Tujuan penelitian yaitu 1)menentukan kepadatan dan biomassa siput gonggong, 2)Pola sebaran dan 3)Karakteristik habitat siput gonggong di ekosistem padang lamun. Penelitian dilakukan di Pesisir Tukak dan Pulau Anak Air, Kepulauaan Bangka Belitung. Pengambilan data di lapangan melputi pengukuran kepadatan, perhitungan tutupan lamun, kerapatan lamun dan pengukuran parameter fisika kimia perairan, sedangkan pengambilan data di laboratorium meiputi, pengukuran biomassa siput gonggong, uji tekstur substrat dan kandungan bahan organik. Karakteristik habitat ditentukan menggunakan analisis komponen utama (PCA), yang menghubungkan antar variabel kepadatan siput gonggong, vegetasi lamun dan parameter fisika kimia perairan. Kepadatan rata-rata siput gonggong di semua stasiun yaitu 2312 ind/ha. Pola sebaran siput gonggong di stasiun penelitian ada pola sebaran seragam dan mengelompok, tetapi secara keseluruhan pola sebaran yaitu mengelompok. Hasil PCA menujukan  siput gonggong, dengan karakteristik habitat yaitu tutupan lamun sangat rendah (1-5 %), ditumbuhi spesies lamun Halophila minor, dengan kondisi substrat pasir berlumpur dan rendah kandungan bahan organik. Selain itu berdasarkan hasil matrik korelasi bagian dari output PCA siput gonggong berkorelasi positif dengan lamun H. Minor (0,88), tutupan lamun sangat rendah (0,86) dan substrat pasir berlumpur (0,9). Hal ini menujukan siput gonggong menepati mikrohabitat yang spesifik di ekosistem padang lamun.