Judul: Keterkaitan diatom perifitik dengan keberadaan unsur hara pada substrat biocrete serta pemanfaatanya oleh udang stadia pascalarva
Abstrak: Penyediaan pakan alami merupakan salah satu upaya pendukung produksi perikanan budidaya yang ramah lingkungan dan berkelanjutan. perifiton adalah salah satu sumberdaya ahayati perairan yang berpotensi sebagai pakan alami biota air (udang). Kelompok penyusun utama komunitas perifiton laut adalah diatom.
Keyword: Biocrete, Zeocrete, Shirmp

Judul: Biomassa diatom perifitik pada susbtrat zeocrete dengan konsentrasi P yang berbeda
Abstrak: Diatom perifitik merupakan salah satu komunitas penyusun perifiton yang dapat dimanfaatkan sebagai pakan alami bagi larva udang. Diatom perifitik dapat hidup di suatu perairan karena perairan mampu memenuhi faktor-faktor biologis yang mendukung pertumbuhannya. Apabila diupayakan suatu tempat hidup bagi diatom perifitik dengan kondisi yang juga mampu memenuhi faktor-faktor biologis yang dibutuhkan, maka diatom perifitik dapat hidup di sana. Oleh karena itu direalisasikan sebuah substrat buatan yang terdiri dari campuran zeolit, semen, ijuk dan unsur hara yang diberi istilah zeocrete sebagai tempat hidup diatom perifitik. Unsur hara yang dikeluarkan oleh substrat zeocrete akan dimanfaatkan oleh diatom perifitik untuk pertumbuhannya. Untuk mengetahui kemampuan substrat zeocrete sebagai tempat hidup bagi diatom perifitik perlu dilakukan pengkajian mengenai biomassa diatom perifitik yang ditumbuhkan pada substrat tersebut.
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Judul: Quantitative Trait Loci Mapping for Trait in Categorical Scale
Abstrak: Genes or regions on chromosome underlying a quantitative trait are called Quantitative Trait Loci (QTL). Characterizing genes controlling quantitative trait on their position in chromosome and their effect on trait is through a process called QTL mapping. In estimating the QTL position and its effect, QTL mapping basically utilize the association between QTL and DNA markers. However, many important traits are obtained in categorical scale, such as resistance from certain disease. From a theoretical point of view, QTL mapping method assuming continuous trait could not be applied to categorical trait. This research was focusing on the assessment of the performance of Maximum Likelihood (ML) and Regression (REG) approach employed in QTL mapping as well as the performance of Lander and Botstein (LB) and Piepho method in determining critical value in testing the existence of QTL for binary and ordinal trait by means of simulation study. The simulation study to evaluate the performance of ML and REG approach was conducted by taking into account several factors that may affecting the performance of both approaches. The factors are: (1) marker density; (2) QTL effect; (3) sample size; (4) shape of phenotypic distribution; (5) number of categories; and (6) number of QTL. Moreover, the simulation study for evaluating LB and Piepho method in determining critical value was conducted by generating distribution of the test statistic under null hypothesis. From simulation study, it was obtained that LB and Piepho method showing similar performance in determining critical value in testing the existence of QTL for binary and ordinal trait. The simulation study also indicating that both methods could be used in determining critical value in QTL mapping analysis for binary trait as well as for ordinal trait if the REG approach is used but not if ML approach is used due to their poor performance. In assessing the performance of ML and REG approach in QTL mapping analysis for binary trait, the two approaches showing comparable performance; whereas for ordinal trait REG approach showing poor performance compared with ML approach in estimating thresholds. As a result, in QTL mapping analysis, ML and REG approach could be used when dealing with binary trait, whereas ML approach is suggested when dealing with ordinal trait.
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