The presence of gastropods and bivalves is always associated with sediment as a substratum and a place to live. The particle size of the sediment is related to the circulation of water which is directly related to the availability of food and oxygen. The purpose of this study was to analyze the dominance of substratum of the waters in relation to the density of gastropods and bivalves in the coastal waters of Tawiri Village. The study was conducted November 2019 in the coastal waters of Tawiri Village. The total gastropod density was 8.31 ind/m2 with an average of 0.16 ind/m2 ±0.34 ind/m2. The highest density value of gastropod species in the coastal waters of Tawiri Village was represented by four species, namely Nerita patula with a density value of 2.38 ind/m2, followed by Nerita polita 0.67 ind/m2 and Clypeomorus subrevicula and Rhinoclavis sinensis with a value of 0.54 ind/m2. The total density of bivalves was 5.46 ind/m2 with an average value of 0.61 ind/m2. The species with the highest density was Ruditapes variegatus with a density value of 2.04 ind/m2, followed by Psammotaea togata at 1.5 ind/m2 and Gafrarium equivocum 0.97 ind/m2. Sediment distributed as a substrate in the coastal waters of Tawiri Village has four dominant categories, namely sandy, rocky sand, sandy stones and rocky. Gastropods are able to live and adapt to sediments with the categories of sandy, rocky sand, rocky and sandy stones. Bivalves are able to live and adapt to sediments with the categories of sandy, rocky sand, rocky and sandy stones.   ABSTRAK Kehadiran gastropoda dan bivalvia selalu terkait dengan sedimen sebagai substrat dasar dan tempat hidup.Ukuran partikel sedimen berhubungan dengan sirkulasi air yang langsung berkaitan dengan ketersedian makanan dan oksigen.  Tujuan penelitian adalah menganalisis dominansi sedimen dasar sebagai substrat dasar perairan hubungannya dengan kepadatan gastropoda dan bivalvia pada perairan pantai Negeri Tawiri. Penelitian ini dilakukan pada bulan November 2019 di perairan pantai Negeri Tawiri. Total kepadatan gastropoda adalah 8.31 ind/m2 dengan rata-rata 0.16 ind/m2 ±0.34 ind/m2. Nilai kepadatan tertinggi spesies gastropoda pada perairan pantai Negeri Tawiri diwakili oleh 4 spesies yaitu Nerita patula dengan nilai kepadatan sebesar 2,38 ind/m2diikuti oleh Nerita polita 0,67 ind/m2 serta Clypeomorus subrevicula dan Rhinoclavis sinensis dengan nilai 0.54 ind/m2. Total kepadatan bivalvia adalah 5.46 ind/m2 dengan nilai rata-rata 0.61 ind/m2. Spesies dengan kepadatan terbesar, yaitu Ruditapes variegatus dengan nilai kepadatan sebesar 2.04 ind/m2,diikuti oleh Psammotaea togata sebesar 1,5 ind/m2 dan Gafrarium equivocum 0.97 ind/m2. Sedimen yang terdistribusi sebagai substrat pada perairan pantai Negeri Tawiri memiliki 4 kategori dominansi, yaitu berpasir, pasir berbatu, batu berpasir dan berbatu. Gastropoda mampu hidup dan beradaptasi pada sedimen dengan kategori berpasir, pasir berbatu, berbatu dan batu berpasir. Bivalvia mampu hidup dan beradaptasi pada sedimen dengan kategori berpasir, pasir berbatu, berbatu dan batu berpasir Kata kunci: Bivalvia, gastropoda, kepadatan, sedimen, perairan pantai Negeri Tawiri

Background: Decreasing of sea cucumber resources on numbers and size of fishing capture in Negeri Porto waters influenced its community structures. Further, water environment steadiness will questionable. For this reason, study was done to analyzed community structures of sea cucumbers include of numbers species found, density, potency, species presence frequency, distribute pattern, ecology index and environment measurement. Method: Research done on February to May, 2008 at Negeri Porto used Line Transect Method. Result: showed there were eight species of sea cucumbers found (potency as much as 12.286 individuals). Bohadschia marmorata got highest in numbers species found, density, potency and species presence frequency. There were three distribute pattern of sea cucumbers found wich are uniform, random and group. Conclusion: Sea cucumbers diversity was in lower, species are closed to compatible. B. marmorata and Holothuria edulis are tends to dominate this water. Environment factors such temperature, pH, salinity, DO, turbidity, current and sediment distribute showed that Porto waters was suitable to sea cucumbers growth.

No abstract

Strombus luhuanus is a marine mesogastropod known as strawberry conch belongs to the Strombidae family. This species is consumed by the coastal community in Maluku province and collected by people at various shell size. The objective of this research was to determine the temporal size distribution and the size difference between its sexes. Sampling was conducted in Oma coastal water, Central Maluku, Eastern Indonesia. A specimen of S. luhuanus collected randomly during low tide from April to July 2018. Some characters of S. luhuanus were measured including shell length, shell width, spire height, and lip thickness. The result of this research showed that shell length of this species varied between 30.81 mm and 55.20 mm; the shell width varied from 16.33 mm to 32.25 mm; its spire height varied between 5.00 mm and 15.20 mm, while the lip thickness varied from 0.10 mm to 5.54 mm. The average of shell length, shell width and spire height of S. luhuanus were high in June sampling period compared to another sampling periods, whereas lip thickness of this species was high in July sampling. Based on its sex, the shell size parameters measured in our study were higher in female specimen than the male one. The size groups of this gastropods were dominated by 38.79-47.39 mm in shell length. Lip thickness of the shell showed that S. luhuanus was in developing stage of growth in this study and S. luhuanus showed sexual dimorphism.

Bulu babi (echinoidae) adalah salah satu sumberdaya perikanan bernilai ekonomis penting dengan permintaan pasar yang cukup tinggi di Asia, Eropa dan Amerika.  Permintaan pasar akan sumberdaya ini dari tahun ke tahun semakin meningkat, akibatnya tingkat pemanfaatan dipacu untuk mencukupi kebutuhan tersebut. Metode pemanfaatan yang banyak dilakukan masyarakat adalah pengambilan hasil produksi dari alam. Tujuan dari penelitian ini adalah menganalisa kepadatan, , Potensi/kelimpahan, frekuensi kehadiran, dan indeks ekologi serta mengkaji kondisi kualitas perairan Dusun Pelita Jaya dan Pulau Osi seperti suhu, salinitas, dan kecepatan arus. Untuk pengambilan sampel digunakan metode transek linier kuadrat dengan jarak transek 50 meter dan jarak antara kuadrat pengamatan 10 meter. Dari hasil penelitian ini maka didapatkan hasil yaitu bulu babi di Pelita Jaya terdiri atas tiga spesies, sedangkan di Pulau Osi  lima spesies. Kepadatan dan frekuensi kehadiran tertinggi di Pelita Jaya diwakili oleh spesies Tripeneustes gratilla, sedangkan Pulau Osi diwakili oleh Diadema setosum. Potensi/kelimpahan bulu babi di Pelita Jaya sebesar 33.033 individu, sedangkan di Pulau Osi sebesar 74.240 individu.  Dari nilai indeks ekologi maka dapat dinyatakan bahwa keragaman di kedua lokasi berada pada kategori sedang, dengan dominasi spesies yang rendah , serta  keserasian spesies bulu babi di dalam komunitasnya berada pada keadaan berimbang (Steady State). Parameter kualitas air (suhu, salinitas, dan kecepatan arus) sesuai untuk pertumbuhan bulu babi di Pelita Jaya dan Pulau Osi.