Judul: Comparison of Spat Bivalvia Recruitment in Rehabilitated Mangrove Ecosystems with Natural Mangroves Rangsang Island, Riau Province
Abstrak: The life cycle found in mangrove bivalves in their growth into adult shells are spat. Spat is a juvenile that has settled on the bottom of the water in an area that is still small with a shell shape resembling an adult shell and will grow and develop in that area. Spat growth until it becomes an adult clam, takes place in the mangrove ecosystem area in brackish waters. The importance of the economic value of bivalves makes the availability of seeds very important. Knowing the type, abundance and life cycle of bivalves is the right step in estimating the ideal time for spacing bivalves. The research was conducted in a natural and rehabilitated mangrove ecosystem on Rangsang Island, Meranti Islands Regency, Riau Province, for 4 (months) months, starting from October to January 2021. The sampling location for A. granosa bilvalvia spat was determined by purposive sampling, which consisted of 2 (two) subzones and each subzone is located in the intertidal zone, namely at the highest high tide and highest low tide point in the mangrove ecosystem area, namely Subzone 1 is located in the lower subzone (Upper) in the highest tide area. Subzone 2 is located in the Upper (Lower) subzone at the lowest ebb and is on the beach. The distance between subzones is 50 meters. The results showed that the distribution of the abundance and spat length of A. granosa bivalves in the natural and rehabilitation mangrove ecosystems on Rangsang Island differed each month (November, December and January). The highest average abundance and length were found in December in rehabilitation mangroves of 79100 ind/100 m2 and 7.67 (±3.94) mm in length and in natural mangroves of 107100 ind/100 m2 and 4.25 (±3.60) in length and with an average mangrove density of 2,283.33 ind/ha and 42,33.33 ind/ha. The species found in the rehabilitated and natural mangrove ecosystems consist of Avicennia alba and Avicennia marina. Comparison of the abundance of Bivalve spats between the rehabilitation mangroves and natural mangroves did not show significant differences either between time periods or between zones. Spat length of A. granosa bivalves was affected (strong category) by pH and temperature. The relationship between mangrove density and A. granosa abundance was in the very strong category in December 2020 and January 2021, while the relationship between mangrove density and A. granosa abundance in November 2020 was in the strong category. The condition factor results showed that Bivalvia A. granosa in the rehabilitation mangrove ecosystem ranged from -5.41 to -1.34 and in natural mangrove ecosystems it ranged from -1.90 to -1.4. From these results the analysis of condition factors in both ecosystems described environmental conditions that were not good enough for A. granosa. So if viewed from these results, the rehabilitation and natural mangrove ecosystem on Rangsang Riau Island is a habitat that is not good for A. granosa to grow.
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Judul: Ecobiology of “Sepetang” (Pharella acutidensBroderip & Sowerby, 1828) clamin mangrove ecosystem Dumai Coastal Riau
Abstrak: The“Sepetang” (P. acutidens) clam population in Dumai mangrove ecosystem seemed to decrease due to the increase of mangrove degradation and clam exploitation. The aims of the study were todetermine the population and reproductive biology character of the“sepetang” (P. acutidens)clam and their relationship with biophysical and chemical characteristic of mangrove ecosystem.The study was carried out from November 2010 to October 2011 inDumai mangrove ecosystem. Population biology aspects such as patterns of the population growth, mortality and recruitment of the clam P. acutidens were determined.Reproductive biology aspects such as sex ratio, gonadal development,gonadosomatic index, fecundity and oocytes diameter were also studied.The “sepetang” clam habitat characteristic was evaluated based on biophysical and chemical parameters of mangrove environment at each station using principal component analysis. Descriptive analysis was used to evaluate relationship between “sepetang” biological character and mangrove ecosystem environment characteristics. Correspondence analysis was used to analyze spatial distribution of “sepetang” clam in relation with biological character. The results showed that the study area was classified into four groups of stations. First, consists of station SM1 and SM2 was characterized by high concentration of nitrate and phosphate, organic sediment, silt fraction, X. granatum andR. apiculata mangrove species density. Seconds, consists of station P1, P2 and P3 characterized by high salinity, sand and clay fraction, and H. littoralis mangrove species density. Third, consist of station SM3 characterized by high pH of water and sediment and plankton density. Fourth, consists of stasion SD1, SD2 and SD3 characterized by high density of B. gymnorrhiza and A. alba. The growth pattern of P. acutidens was negative allometric with asymptotic length (L ) was 92.71 mm. The annual growth coefficient (K) and total mortality were 0.59 and 1.87 per year, respectively. The recruitment occurred every month.Sex of the sepetang clam can be determined at the size more than 35 mm. The male to female ratio was 1 : 1.12 and no specimen hermaphroditism was observed. Histological analysis indicated that P. acutidenswas partially spawned. The fecundity increase with an increase of shell length and correlated significantly with shell length. The sepetang clam probably spawn continuously throughout the year with a peak spawning season between May-June. The results showed that high gonadosomatic index and fecundity of “sepetang” clam in station SM1, SM2 and SM3. The stations were characteristized by high organic sediment, silt fraction, andR. apiculata density.
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Judul: Pembuatan dan Karakterisasi Prototipe Sel Surya Nanokristal n-TiO2/Dye/p-CuSCN
Abstrak: Dengan metode casting dan perlakuan annealing, dapat dibuat lapisan nanokristal semikonduktor TiO, pada substrat Transparant Conductive Oxide (TCO). Penambahan dye Methylviolet Thiocianate (MVSCN) dan lapisan CuSCN pada TiO, tersebut menghasilkan sel surya n-TiO,ldye/p-CuSCN yang dapat menyerap foton dan mengubahnya menjadi energi listrik.
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