Food Preference Of Shortfin Scad (Decapterus Macrosoma) At The Southern Waters Of Gunungkidul YOGYAKARTA, Indonesia [Preferensi Pakan Ikan Layang Deles (Decapterus Macrosoma) di Pantai Selatan Gunungkidul YOGYAKARTA]

Kebiasaan pakan ikan merupakan salah satu informasi penting yang digunakan dalam manajemen sumberdaya perikanan. Penelitian ini bertujuan untuk mengetahui preferensi pakan, indeks bagian terbesar dan tingkat trofik ikan layang deles (D. macrosoma) yang ditangkap dari Perairan Gunungkidul. Total 325 sampel ikan layang deles dikumpulkan selama bulan Maret sampai dengan September 2018. Setiap sampel ikan diukur panjang total, berat tubuh, ditentukan jenis kelaminnya kemudian dilakukan pembedahan. Saluran pencernaan diukur panjangnya, kemudian isi lambung ikan diawetkan dalam formalin 5% untuk diamati komposisi jenis makanannya. Analisis data meliputi panjang usus relatif, frekuensi kejadian, indeks bagian terbesar, dan tingkat trofik ikan layang deles. Hasil penelitian menunjukkan bahwa ikan layang deles bersifat karnivora (panjang usus relatif = 0,47) dengan komposisi jenis makanan utama adalah ikan (84,15%). Makanan pelengkap layang deles adalah fitoplankton (8,91%), sedangkan zooplankton (4,47%) dan potongan udang (3,19%) merupakan makanan tambahan. Berdasarkan identifikasi molekuler, spesies ikan yang menjadi makanan utama ikan layang deles adalah Cololabis saira (Scomberesocoidae)

The Effectiveness of Seaweeds as Biofilter for Reducing Wastewater Nutrient and Preventing Water Pollution From Hybrid Grouper Culture

Highlight ResearchWastewater in hybrid grouper culture should be maintain before resirculate and dispose to aquatic environment to avoid eutrophication.Seaweed that is used for biofilter must be observed for its suitability, performance and effectivity.Ulva sp. has the best effectiveness to reduce nutrient in wastewater of hybrid grouper aquaculture by absorbing then stored into thallus.Ulva sp. is proven has the best SGR and adaptability in wastewater of hybrid grouper culture.AbstractWastewater generated from hybrid grouper culture needs to be managed to improve water quality before being recirculated, or discharged in the aquatic environment. Seaweed biofilter has been proposed in wastewater treatment technology for marine fish farming. This study aimed at comparing which of these species i.e. Ulva sp., Sargassum sp., Gelidium sp., and Dictyota sp. work best to absorb nutrient wastewater hybrid grouper culture. This research utilized these seaweed as treatments and controls with three replications using Completely Randomized Design. A statistical analysis was conducted to investigate the significant differences in the nutrient absorptions among various seaweed species by using ANOVA and least significant difference. Non-parametric tests namely Kruskal-Walis, Mann-Whitney, and t-test were used with confidence interval of 95%. The results revealed that Ulva sp. has the best ability to reduce the Nitrogen 80%, while Dictyota able to reduce Phosphor 88% by Dictyota sp. generated from wastewater of hybrid grouper culture. While the highest absorbtion of Total Kjeldahl Nitrogen (104%) and phosphate (182%) that stored in thallus were performed by Ulva sp. Ulva sp. had the best performance and highest growth rate (1.9% d-1) as biofilter in hybrid grouper cultivation than other species