No abstract

Abstract. Red macroalgae have the potential to be processed into bioethanol due to their high carbohydrate and low lignin content. Gelidium latifolium and Gracilaria verrucosa are red macroalgae commonly found in Indonesian seas. Sometimes an over-supply of red macroalgae is rejected by the food industry, which opens up opportunities for others uses, e.g. for producing bioethanol. The objectives of this research were to analyze the influence of sulfuric acid concentration on hydrolysis of G. latifolium and G. verrucosa and to calculate the optimum fermentation process to produce bioethanol. G. latifolium and G. verrucosa were hydrolyzed using H 2 SO 4 at concentrations of 1%, 2%, 3%, and 4%, at a temperature of 121 °C and a pressure of 1.5 bar for 45 minutes. The process of fermentation was done using Saccharomyces cerevisiae in anaerobic conditions for 4, 5, 6 and 7 days. The results show that the optimum H 2 SO 4 concentrations to hydrolyze G. latifolium and G. verrucosa were 1% and 2% respectively. The number of S. cerevisiae cells in hydrolysate G. latifolium and G. verrucosa increased in the third adaptation. S. cerevisiae can convert sugar from G. latifolium and G. verrucosa into bioethanol through fermentation. The highest bioethanol yields were achieved on days five and six. Therefore, red macroalgae can be seen as a potential raw material for bioethanol production.

Penelitian ini dilaksanakan di Desa Bakau Besar dan Bakau Kecil Kabupaten Mempawah pada bulan Maret sampai April 2021. Tujuan penelitian ini adalah untuk mengetahui perubahan jenis mangrove, kerapatan dan keanekaragaman mangrove. Jumlah stasiun penelitian sebanyak 4 stasiun terdiri dari 2 stasiun di Desa Bakau Besar dan 2 stasiun di Desa Bakau Kecil, dilakukan menggunakan metode purposive sampling.  Pengamatan dilakukan dengan jarak 100 m dari bibir pantai dan jarak antar plot 100 m. Setiap stasiun dibagi menjadi 2 plot menggunakan plot persegi dengan kriteria pohon, pancang dan semai. Berdasarkan hasil penelitian didapatkan jenis mangrove yang berbeda dari penelitian sebelumnya yaitu Ceriops tagal, Bruguiera gymnorrhiza, dan Sonneratia alba yang didapat di Desa Bakau Besar sedangkan di Desa Bakau Kecil didapatkan 1 jenis mangrove yang berbeda dari penelitian sebelumnya, yaitu: Rhizophora lamarckii. Kerapatan jenis mangrove tingkatan pohon tergolong rendah sebesar 450 ind/ha di Desa Bakau Besar dan 300 ind/ha di Desa Bakau Kecil, sedangkan untuk tingkat pancang di kedua desa tergolong sedang dengan nilai 1300 ind/ha di Desa Bakau Besar dan 1400 ind/ha di Desa Bakau Kecil hanya tingkat semai yang tergolong tinggi yaitu 10.625 ind/ha di Desa Bakau Besar dan 5625 ind/ha di Desa Bakau Kecil. Sementara keanekaragaman jenis mangrove di Desa Bakau Besar tergolong sedang kecuali tingkat pancang yang tergolong rendah, sedangkan di Desa Bakau Kecil keanekaragaman jenis tergolong rendah hanya tingkat pancang tergolong sedang.

Seagrass is one of productive and economical marine ecosystem, but recently there are indications that this area is decreasing and every kind of damage is happening. The research was conducted to reveal the change of seagrass width area and to determine the suitable location for donor and acceptor of seagrass transplantation. Methods of research were collecting and analyzing the satellite image of the research location, bathymetri mapping and water quality parameter, and also determining environment charasteristics that suitable to be performed by counting Seagrass Transplantation Suitability Index (STSI). The results show that in year 1999-2004, the derivation area of seagrass was 678.300 m2. Pari island has depth range between 0-50 metres and the physics and chemical parameter of water have a good range where the seagrass can live. According to the analysis result of STSI, suitable areas for seagrass transplantation donor is station no. 5 and 6 for seagrass species of Enhalus acoroides and station no. 2 and 7 for seagrass species Thalassia hemprichii. The implication of this research is that the seagrass needs rehabilitation to overcome seagrass ecosystem for better condition.