Beginer Subhan

STUDY ON BIOROCK® TECHNIQUE USING THREE DIFFERENT ANODE MATERIALS (MAGNESIUM, ALUMINUM, AND TITANIUM)

Biorock® technique is the earliest methods to rehabilitate the damage of coral reef ecosystem. Its improvement is need to carry on since it is subject to some inhibitions in particular the dependence of expensively-imported Titanium (Ti) as the anode materials. The main purpose of this research was to find the best anode material as a possible subtitution which can be economically and easily to apply in Indonesia. Therefore we compared Titanium (Ti) with two other potential anodes material (Magnesium-Mg, and Aluminum (Al). The laboratory study was carried out for two days period (48 hours) in the stagnant sea water aquaria. Four aquarium tanks were treated by different electric current treatment (1 Ampere, 2 Ampere, 3 Ampere, and 5 Ampere, respectively). The reduction of electrode weigh (anode and cathode) was measured. During the experiment, water quality (i.e. pH, and salinity) and mineral waters (calcium) were collected every 6 hour in 48 hours. The solid form of calcium carbonate was analyzed using XDS (X-ray Dispersion Spectrophotometer). The accretion rates on cathode and anode decay were compared between anodes which were treated by different electrical current. Based on the study, three anodes (aluminum, magnesium and titanium) showed different respond. Titanium and Magnesium anode showed electric current affected accretion rate (P < 1), while for aluminum anode showed no differences on treatments.

Strong genetic differentiation in tropical seagrass Enhalus acoroides (Hydrocharitaceae) at the Indo-Malay Archipelago revealed by microsatellite DNA

The Indo-Malay Archipelago is regarded as a barrier that separates organisms of the Indian and Pacific Oceans. Previous studies of marine biota from this region have found a variety of biogeographic barriers, seemingly dependent on taxon and methodology. Several hypotheses, such as emergence of the Sunda Shelf and recent physical oceanography, have been proposed to account for the genetic structuring of marine organisms in this region. Here, we used six microsatellite loci to infer genetic diversity, population differentiation and phylogeographic patterns of Enhalus acoroides across the Indo-Malay Archipelago. Heterozygosities were consistently high, and significant isolation-by-distance, consistent with restricted gene flow, was observed. Both a neighbour joining tree based on DA distance and Bayesian clustering revealed three major clusters of E. acoroides. Our results indicate that phylogeographic patterns of E. acoroides have possibly been influenced by glaciation and deglaciation during the Pleistocene. Recent physical oceanography such as the South Java Current and the Seasonally Reversing Current may also play a role in shaping the genetic patterns of E. acoroides.

Variasi Geografik Kelimpahan Zooplankton di Perairan Terganggu, Kepulauan Seribu, Indonesia

Zooplankton play a significant role in ecosystem as secondary producer. Climate change will potentially affect the abundance and global composition of zooplankton. This research aimed to study the geographical variation of zooplankton abundance relative to anthropogenic pressure. The research was conducted in April 2014 in area with presumably distinct anthropogenic level by its relative distance to the mainland of Jakarta. Samples were collected at Pramuka Island, Karang Beras Island, Kotok Island, and Sepa Island where subsequently lying to the nearest until furthest distance from mainland. Zooplankton samples were collected by towing the plankton net for 10 minutes for each site for three replicates. Abundance was obtained from Pramuka Island was 266698,214 ind/L, Karang Beras Island was 597363,1 ind/L, Kotok Island was 526447,8 ind/L and Sepa Island was 438225,3 ind/L. Overall, the closer to mainland, the richer nutrient and the more abundant zooplankton was conceived in the waters. Surprisingly, in Pramuka Island, the nearest island to mainland among other sites, had the lowest abundance of zooplankton although nutrient level was the richest among others.