No abstract

Mangrove menghasilkan serasah yang akan mengalami proses dekomposisi yang kemudian dimanfaatkan sebagai sumber hara bagi tanaman dan juga merupakan sumber makanan bagi ikan serta invertebrata yang penting. Tujuan dari penelitian ini adalah untuk mengukur dekomposisi serasah daun R. apiculata dan mengetahui kandungan unsur hara karbon (C), nitrogen (N) dan fosfor (P) pada serasah daun Rhizophora apiculata yang dilepas selama proses dekomposisi. Penelitian dilakukan pada bulan Februari hingga Mei 2017 di Desa Bagan Asahan Kecamatan Tanjungbalai Kabupaten Asahan Provinsi Sumatera Utara. Penentuan stasiun penelitian menggunakan metode purposive sampling pada tiga stasiun dengan penentuan stasiun berdasarkan pengamatan ketersediaan jenis mangrove R. apiculata. Hasil penelitian menunjukkan laju dekomposisi serasah daun R. apiculata pada hari ke-90 yaitu pada stasiun I bernilai 13,04 stasiun II bernilai 11,42 dan stasiun III bernilai 10,24. Kandungan unsur hara karbon selama proses dekomposisi 90 hari yaitu stasiun I sebesar 16,24 %, stasiun II sebesar 15,29% dan stasiun III sebesar 15,42 %. Unsur hara nitrogen yang terdekomposisi pada hari ke 90 yaitu stasiun I sebesar 2,69%, stasiun II sebesar 2,57 % dan stasiun III sebesar 2,75%. Kandungan unsur hara fosfor selama proses dekomposisi 90 hari yaitu stasiun I 0,02 %, stasiun II 0,02 % dan stasiun III 0,01 %.Mangroves produced litter that will undergo decomposition process which used as a source of nutrients for plants and also source of food for fish and important invertebrates. The purpose of this research is to measure the decomposition of Rhizophora apiculata leaf litter and to know the content of carbon (C), nitrogen (N) and phosphorus (P) nutrient in leaf litter of R. apiculata released during the decomposition process. The research was conducted from February to May 2017 in Bagan Asahan Village, Tanjungbalai District, Asahan Regency, North Sumatera Province. The method of this research used purposive sampling and determined three stations sampling based on observation of availability R. apiculata mangrove species. The result showed that decomposition rate of R. apiculata leaf on the 90 day at station I was 13,04, station II was 11,42, and station III was 10,24. The content of carbon nutrients during the 90 day decomposition process in station I was 16.24%, station II was 15.29% and station III was 15.42%. Nitrogen nutrient elements decomposed on the 90 day were station I was 2.69%, station II was 2.57% and station III was 2.75%. Phosphorus nutrient content during 90 day decomposition process was 0,02% for station I, 0,02% for station II and 0,01% for station III.

Abstract. Coral reefs are one of the most highly productive marine ecosystems, with the largest transfer of energy attributed to the trophic interaction between herbivores and algae. Rapid demographic growth, leading to transmigration to small islands such as Natuna Island where located on outer Island Indonesia.The aim of the present study is to test for significant associations between herbivore fish species traits and Habitat complexity was derived from coral reef cover. Method to record each observed herbivore fish species with UVC (Underwater Visual Census) using SCUBA diving equipment along modification line transects. A total of 39 different fish species belonging to 3 families" herbivore fish were identified. Total biomass of herbivorous fish correlated with Dead Coral Algae (DCA). Biplot of the first two axes for the nonmetric multidimensional a scaling (NMDS) analysis for family and grazer showed the dominance of herbivore fish grazer.

Apriadi T, Pratama G, Putra RD, Jumsurizal, Jaya YV, Firdaus M, Arpas HD, Suryanti A. 2018. Comparative study on the fish diversity from natural and bauxite post-mining in wetland system of Bintan Island, Indonesia. Biodiversitas 19: 967-973. In this study, the fish populations between two different wetland systems in Bintan Island, Indonesia, i.e., bauxite post-mining (Kijang) and natural wetland (Toapaya) were compared and to propose a newly index namely Environomic of Fishes Index (EFI) to their respective ecosystems. The purposive random sampling at six stations, each of three stations representing bauxite mining (Kijang) and three stations representing a natural wetland (Toapaya) were used in this research. The numbers of fish species and the abundance were enumerated. The new index derived from the value of diversity index (Shannon), similarity index (Evenness), dominance index (Simpson's), conservation status, and economic value were also evaluated. The natural wetland has higher fish diversity than bauxite post-mining. The total species found were twenty-four. The same seven species were found in both areas. Twelve species were obtained from bauxite post-mining, and nineteen species were obtained from natural wetland. Puntius tetrazona and Rasbora heteromorpha were the common species in area study. The diversity and dominance index was at low category, Evenness index was at high category in all stations, except in tidal swamp station at bauxite post-mining. The EFI in natural wetland was higher than bauxite post-mining. The three community index value, economic value, and conservation status of natural wetland were higher than bauxite post-mining.

Sei Nipah has enormous potential for natural resources. Natural resources that serve as the main livelihood in fulfilling daily needs in Kampung Nipah is shellfish. Shellfish (M. meretrix) is one of the shells that many interested by the surrounding community. The purpose of this research is to know growth parameter and age group of shellfish (M. meretrix) in Kampung Nipah. The sampling technique was done randomly (simple random sampling). Sampling time is done at low tide. Sampling was conducted in March - May 2017. The results showed differences in the length of different shells each month. The size group of shellfish (M. meretrix) found only one size group during the three months of the study. Analysis of shellfish growth parameters based on data of long frequency distribution showed length of infiniti (L?) 33,10 mm and growth growth (K) that was 1,21 per month. Von Bertalanffy Growth Parameters Lt = 33.1 (1-e [-1.21 (t + 0.12)]) Long infiniti size is seen the growth of shellfish shells can no longer be worked Shells reach maximum length at the age of 13 months with a shell length of 33.10 mm.The youthful shells have rapid growth and as age increases, when it reaches old age the rate of growth will slow even.

One of the economically important fish included in the Plotosidae family is the Sembilang Fish. This study aims to determine the growth patterns and condition factors of the Sembilang fish. The research was conducted in July 2018. The locations of the Sembilang Fish sampling station include Dompak Island Bay, Bugis Village Bay, Madong Bay, Pengujan Bay and Tanjung Uban. The total sample of Sembilang Fish that has been obtained is 150, consisting of 80 males and 70 females. Total length ranges from 19.7-66 cm, with weights ranging from 33.68-960 g. The mode of distribution of the frequency of the fish caught during the study was in the second class interval, namely 25.7-30.7. The relationship between the length and weight of male Sembilang fish is W = 0, 0268L2,5378 and the female is W = 0, 00542L2,3347. The growth pattern of Sembilang fish, both male and female, is negative allometric which shows the length growth is faster than the weight. Fish condition factors obtained during the study ranged from 0.723 to 1.166.Keywords:BintanCondition FactorLength-weight-relationshipPlotosus caniusSembilang fish ABSTRAKSalah satu ikan ekonomis penting yang termasuk dalam famili Plotosidae adalah Ikan Sembilang. Penelitian ini bertujuan untuk mengetahui pola pertumbuhan dan faktor kondisi ikan sembilang. Penelitian dilaksanakan pada bulan Juli 2018. Lokasi stasiun pengambilan sampel Ikan Sembilang diantaranya Teluk Pulau Dompak, Teluk Kampung Bugis, Teluk Madong, Teluk Pengujan dan Tanjung Uban. Total sampel Ikan Sembilang berjumlah 150 ekor, terdiri dari 80 ekor jantan dan 70 ekor betina. Ukuran panjang total berkisar antara 19,7-66 cm, dengan berat berkisar antara 33,68-960 g. Modus distribusi frekuensi ikan sembilang yang tertangkap selama penelitian ada pada selang kelas kedua yaitu 25,7-30,7. Hubungan panjang dan bobot Ikan Sembilang jantan adalah W = 0, 0268L2,5378 dan betina adalah W = 0, 00542L2,3347. Pola pertumbuhan Ikan Sembilang baik jantan maupun betina adalah alometrik negatif yang memperlihatkan pertumbuhan panjang lebih cepat daripada bobotnya. Faktor kondisi ikan selama penelitian nilainya berkisar antara 0,723 hingga 1,166.Kata kunci: BintanFaktor kondisiHubungan panjang-bobotPlotosus caniusIkan Sembilang

Penelitian ini bertujuan untuk mengetahui jenis makanan, dan rasio panjang usus ikan sembilang pada perairan Kota Tanjungpinang yang meliputi index of preponderance dan indeks kepenuhan lambung. Lokasi sampling ditentukan berdasarkan metode purposive sampling dengan menetapkan 3 stasiun pengamatan dan 3 kali pengulangan yang dilaksanakan pada November 2018 sampai Maret 2019. Analisis data yang dilakukan yaitu rasio panjang usus dengan panjang total, indeks bagian terbesar, dan indeks kepenuhan lambung. Hasil penelitian menunjukkan bahwa nilai rasio panjang usus dan panjang total masing-masing pada sembilang jantan dan betina di ketiga stasiun sebesar 1,24;1,26:1,30. Index of preponderance berkisar 34,4 – 50,2%  pakan utama pada umumnya terdiri dari kelompok, kepiting, kerang, udang dan siput sehingga dapat disimpulkan ikan sembilang bersifat karnivora. Makanan pelengkap ikan sembilang dijumpai seperti detritus dan juga dari spesies Fitoplankton (Mikroalgae) yaitu Acinastrum sp. Chlorella sp. Pediastrum sp. Characium sp. Anabaena sp. Thalasionema sp. Oscillatoria sp. Ceratium sp. Peridinium sp. Navicula sp. Gyrosigma sp.

<strong>Food and Feeding Habits of Dog Conch (<em>Laevistrombus turturella</em>) on Penyengat Island, Tanjungpinang</strong>. Dog conch (Laevistrombus turturella) in Tanjungpinang, including commodities of high economic value. The purpose of this study was determine the ratio of the length of gut and the total body length, type of food and feeding habits of dog conch on the Penyengat Island, Tanjungpinang, Riau Islands. The study was conducted from May to November 2019. The sampling location was determined based on the purposive sampling method. The station were divided into 3 stations based on 1) the catch zone of the dog conch, 2) the characteristics of the dog conch habitat and 3) activities along the coast. Analysis of the data were provided the ratio of the length of gut and the total body length, index of preponderance, Viscero Somatic Index (VSI), total organic matter and index of electivity. The results showed that the ratio of the length of gut and the total body length of the dog conch were 1,53; 1,60; 1,66 and classified as an omnivore based on the ratio of the length of gut and the total body length.  Types of dog conch food that have been found were detritus and microalgae class <em>Bacillariophyceae, Chlorophyceae,</em> and <em>Crustaceans</em>.  The feeding habits of dog conch were detritus with the index of preponderance of 65-70% as the main food.  VSI values were ranged from 24,27 to 36,35%.  Value Index of electivity were ranged from 0,99-1% or close to 1.