Maninjau Research Articles

An application of maximum entropy model to evaluate the differential effect of cage aquaculture on the distribution of a native and an endemic fish species in Lake Maninjau, Indonesia

Physical cage aquaculture structure can attract native fish species in marine and freshwater ecosystems. Most studies on the effects of cage farms on native fish distribution have been undertaken in marine environments and outside of Asia as the main freshwater cage aquaculture producing region. Many studies have emphasised connections between native fish distribution and feeding time. Previous research also has shown the necessity to use modelling to monitor this effect to reduce data collection costs. Here we analyse the distribution of an endemic fish species, Rasbora maninjau, and a native fish, Gobiopterus sp., associated with tilapia cage aquaculture occurrence using a Maximum Entropy Model (MaxEnt). We find that the application of the MaxEnt model can produce reliable and accurate information on the impacts of cage aquaculture on the native fish species distribution aligning with the more expensive count data method. Our results also suggest that the species-specific interaction between the native fish and cage farms is mainly arising from an interaction between the ecological behaviour of the native fish with dimensions of the environmental condition such as turbidity. Our study therefore highlights the importance for improved appraisal of the ecology of native fish in the cage aquaculture risk assessment.

UTILIZATION OF REMOTE SENSING IMAGES IN MAPPING SUSPENDED SOLID IN LAKE MANINJAU WEST SUMATRA PROVINCE

Remote sensing is generally defined as the technical art of obtaining information or data regarding the physical condition of an object or object, target, target or area and phenomenon without touching or direct contact with the object or target (Soenarmo, 2009). With remote sensing data, this research can easily see how the condition of the lake water. Based on these factors, efforts are needed to monitor the distribution of TSS in Lake Maninjau considering the importance of water potential to support various needs. In this study the classification was divided into 5 for the first class with concentration values of tss- 0 – 15 mg/L, 15 – 25 mg/L, 25 – 35 mg/L, TSS 35 – 80 mg/L, TSS > 80 mg/L. The result of in situ data processing is the lowest value is 8.2 mg/L and the highest is 72.2 mg/L. The Syarif Budhiman algorithm has the lowest at 8.14 mg/L and the highest at 40.04 mg/L. The lowest Parwati algorithm is 3.32 mg/L and the highest is 32.86 mg/L. The Guzman - Santaella algorithm has the lowest at 3.15 mg/L and the highest at 164.38 mg/L. The TSS concentrations in the alleged party and budhiman algorithms tend to have the same pattern as the TSS concentrations in the field, but there are several points with significant differences. The validation test shows that the Budhiman Algorithm (2004) has the smallest NMAE value between in situ data and image processing with a value of 14.4%.

Isolation and Analysis of Heavy Metal Content in Scales from Three Species of Farmed Fish in Lake Maninjau

The study isolated and analyzed heavy metal content in fish scale from Osphronemus goramy, Cyprinus carpio, and Oreochromis niloticus in Lake Maninjau. Fish weights (n=10) for O. goramy, C. carpio, and O. niloticus were 389.99±24.96 g, 633.30±87 g, and 210.5±12.12 g. Isolation begins with washing scales using running water, followed by 24-hour immersion in 10% NaCl (1:10 w/w) in a refrigerator. Afterward, they are oven-dried at 50°C for 3.5 hours and ground into powder. Fish scale results were analyzed using the dry weight/wet weight formula x 100. AOAC-compliant spectrometry tested heavy metal concentrations of Hg, Pb, Cr, As, Ag, and Cu. Results for O. goramy, C. carpio, and O. niloticus were 65.85%, 61.68%, and 55.63%, respectively. The concentration of heavy metals in O. goramy showed the highest level was Pb (185 mg/kg), followed by Cu (83 mg/kg), Ag (<14.66 mg/kg), Cr (<5 mg/kg), Hg and As (0.43 mg/kg). In C. carpio the highest concentration was Pb (152 mg/kg), followed by Cu (121 mg/kg), Cr (50 mg/kg), Ag (15 mg/kg), Hg and As (<0.50 mg/kg). Meanwhile, in O. niloticus, the highest concentration was Cu (160 mg/kg), followed by Pb (149 mg/kg), Cr (50 mg/kg), Ag (15 mg/kg), Hg and As (< 0.50 mg/kg).

The Feasibility of West Sumatra Folklore as Indonesian Literature Teaching Material in High School

Cultural and social values that exist in Indonesia need to be taught, considering that current technological advances have an impact on the reluctance of students to learn about cultural and social values. Therefore, Indonesian language and literature teachers should be able to present learning that is integrated with cultural and social values in Indonesia. The reading texts of folklore in Indonesian teaching materials generally come from various regions in Indonesia. Judging from various folklore documentation, West Sumatra is actually rich in folklore. Each region in West Sumatra has interesting folklore and contains educational values. Of course, to be used as teaching material, there needs to be a feasibility test on these folk tales. The origin of the selected folklore texts also varies, namely the Legend of Sabai Nan Aluih from Luhak Tanah Datar, the Legend of the Origin of Lake Maninjau from Luhak Agam, the Legend of Tuanku Taram from Luhak 50 Kota, the Legend of Batu Puti from Sijunjung and Lebai Malang from the Andalas area. The respondents of this study are two teachers of Indonesian Language and Literature at the six sample schools, namely SMAN 1 Banuhampu and SMAN 2 Tilatang Kamang from Agam Regency, SMAN 1 Pariangan and SMAN 1 Batipuah from Tanah Datar Regency, and SMAN 1 Suliki and SMAN 1 Harau from District 50 Kota. The teachers were given an instrument in the form of a questionnaire consisting of five questions for each folklore. As a result, there are five indicators to determine the feasibility of West Sumatra folklore used as teaching materials, namely the language of this folklore is easy to understand, appreciative, educates characters, develops imagination, interesting, and gets a "Good" category rating.Keyword: dance, ilau, cultural homogenization

Semarak Perkembangan dan Pertunjukan Tambua Tasa di Tengah Kehidupan Sosiokultural Masyarakat Selingkar Danau Maninjau

Purpose: Tambua Tasa is a form of traditional music that grows and develops in Minangkabau, especially the people around Lake Maninjau, Agam Regency, West Sumatra. Substantively, what I want to put forward in this paper is a narrative about the splendor of the Tambua performance in the midst of the socio-cultural life of the community, both in the context of traditional ceremonies and socially. Research Methods: The data in this paper are based on the results of observations, interviews, document studies from print and electronic media information (google, you tube and FB) which are analyzed in depth to obtain reliable information. Results and Discussion: Tambua Tasa has experienced very rapid development amidst the socio-cultural life of the people around Lake Maninjau, West Sumatra. Tambua tasa, which in the past only developed and belonged to the village, has now expanded into the world of education, starting from the elementary school level to the high school level. Implication: The transfer of generations from traditional music is also going very well with the emergence of young talents full of talent.

Comparison of bioconcentration factor of heavy metals between endemic fish and aquacultured fish in Maninjau Lake, West Sumatra, Indonesia

Abstract. Komala PS, Azhari RM, Hapsari FY, Edwin T, Ihsan T, Zulkarnaini, Harefa M. 2022. Comparison of bioconcentration factor of heavy metals between endemic fish and aquacultured fish in Maninjau Lake, West Sumatra, Indonesia. Biodiversitas 23: 4026-4032. Fish have a high risk of accumulating metals and poses a risk of entering human bodies through the food chain. This study aims to analyze the concentration of lead (Pb), mercury (Hg), and cadmium (Cd) spatially and temporally as well as the Bioconcentration Factor (BCF) in endemic fish (Rasbora argyrotaenia) and aquacultured fish (Oreochromis niloticus) in Maninjau Lake and its relationship to environmental parameters (pH, DO and temperature). Sampling was conducted at domestic, hydropower, fish cage, and endemic fisheries. Spatial and temporal distribution using one-way ANOVA with 95% significance, while parameter correlation using linear regression. Almost all heavy metals in both fish samples exceeded the permissible level except in endemic fisheries sites. Metal concentrations in both fish species spatially showed a significant difference, while temporally showed no significant difference. Rasbora argyrotaenia showed a slightly higher BCF value than O.niloticus. The BCF values were low accumulative with order Pb>Hg>Cd ??in R. argyrotaenia and Pb>Cd>Hg for O. niloticus. There is a strong and positive correlation between temperature and the BCF value of both fish species for the three different metals. Monitoring fish by keeping metal content within acceptable limits is necessary. Further research on risk analysis of fish consumption in humans is recommended.

Functional Groups of Phytoplankton and Their Relationship with Environmental Factors in Lake Maninjau, West Sumatra, Indonesia

Lake Maninjau is a eutrophic lake indicated by the frequent occurrence of cyanobacterial blooms. The phytoplankton functional groups (FGs) reflect the environmental characteristics and can be useful to monitor the trophic state and evaluate lake’s environmental conditions. This study aims to perceive the composition of phytoplankton FGs and their relation to the environmental factors in Lake Maninjau. The data including phytoplankton and environmental factors were collected in 2001, 2005, 2009, 2014, 2015, 2016, and 2018. There were 21 FGs of phytoplankton recorded in Lake Maninjau. FGs of D, J, F, and NA were commonly found in this Lake. The phytoplankton FGs reflected the dynamic of the environmental characteristics of the lake. The FGs NA representative of oligo to mesotrophic habitat type were predominated accounting for 66.3% to 67.69 % in May 2005 with the lake’s conditions characterized by low TP concentration, high Secchi depth and TN: TP ratio. The FGs of M representative of eutrophic to hypereutrophic habitat type were predominated accounting for 74.14 % to 94.96 % in April 2018 with the lake’s conditions characterized by high TP concentration, low TN: TP ratio, and Secchi depth. A canonical correspondence analysis (CCA) showed that temperature, conductivity, and total phosphorus are important environmental factors to have influenced the succession of phytoplankton FGs in Lake Maninjau.

Morphological Characteristics and Elemental Composition of Magnetic Minerals from the Volcanic Activity of Lake Maninjau Sediments

Lake Maninjau has formed by the eruption of the Maninjau volcano, which spewed volcanic material to various places. This volcanic material contains various mineral-forming elements, one of which are magnetic minerals that accumulate in lake sediments. This research aims to determine the morphological characteristics and composition of magnetic mineral elements from volcanic activity in the sediments of Lake Maninjau, Agam Regency, Indonesia. Characteristics of morphological and composition of magnetic mineral elements originating from volcanic activity can describe volcanic eruptions in the past. So, this research is very important for paleo-eruption studies because it can be used as supporting information to determine the distribution of volcanic ash from a volcanic eruption in the past based on the magnetic properties of the material. The sample was selected from the core MAN 18-41B site 12 with a depth of 35 - 36 cm because it has a high magnetic susceptibility value. Morphological images of lake sediment magnetic minerals were viewed using a SEM instrument and EDS detector that shows the composition of the elements that arrange magnetic minerals. In general, the analysis of morphological images shows that the magnetic mineral grains in the Maninjau lake sediments are irregular and porous. This indicates that the magnetic minerals originate from volcanic activity. The image produced by Back Scattered Electron (BSE) has a difference in brightness on the surface of the magnetic grains, which indicates that the bright surface contains high Fe elements and the dark surface contains high Si. The spectrum generated by EDS shows that the dominant elements present in magnetic minerals in lake sediments are Fe, Ti and Si. Based on the morphology and elemental composition, it is indicated that the minerals contained in the sediments of Lake Maninjau come from volcanic activity.
 HIGHLIGHTS
 
 Lake Maninjau has formed by the eruption of the Maninjau volcano, which spewed volcanic material to various places. This volcanic material contains various mineral-forming elements, one of which are magnetic minerals that accumulate in lake sediments
 Characteristics of morphological and composition of magnetic mineral elements originating from volcanic activity can describe volcanic eruptions in the past
 Morphological forms can provide information about the source of magnetic minerals derived because magnetic minerals have different properties, types, and morphology depending on the source
 Maninjau Lake sediments are dominated by Iron (Fe), Silica (Si), and Titanium (Ti). Based on the morphological images and elemental composition, the magnetic minerals present in the Maninjau lake sediments are indicated to come from volcanic activity
 
 GRAPHICAL ABSTRACT

Distribution of Pyroclastic Deposits around Lake Maninjau Agam District, West Sumatera, Indonesia based on Magnetic Susceptibility

Lake Maninjau is an erupting volcano in West Sumatra Province. The results of the eruption have now settled in various places and scattered in all directions due to the transportation process. The process of transporting volcanic material is caused by several factors such as wind and rain. This study aims to analyze the distribution pattern of volcanic material that is scattered around Lake Maninjau, Agam Regency. We have 25 types of samples divided into 3 categories. There are pumice, lava, and ash. This research was conducted at the FMIPA UNP Laboratory using the rock magnetization method. In this study, a Bartington MS2 with MS2B sensor was used by calculating the magnetic susceptibility value based on the mass of the sample. The results of the magnetic susceptibility analysis obtained varied between 74.7×10-8 - 3956.7×10-8 m3/kg which is included in the ilmenite (FeTiO3) group. The highest value of vulnerability was 2800×10-8 - 4000×10-8 m3/kg found at the core of Lake Maninjau ± 5.0 km seen from the green contour map. The lowest magnetic susceptibility values ​​0 - 800×10-8 m3/kg were found in the western part of Lake Maninjau and the material was deposited at a distance of ± 13 km from the core of the Maninjau caldera. Deposits were also found in the eastern part of Lake Maninjau ± 22.4 km from the core of Lake Maninjau and to the Middle East ± 23 miles from the core of the Maninjau caldera. The white color represents 1600 - 2000×10-8 m3/kg which is included in the moderate magnetic susceptibility value, which is ± 4 km to the southeast of the Maninjau caldera. The benefit that can be taken from this research in the ink industry is the presence of a magnetic mineral distribution map based on suseptibility values ​​and makes it easier to find raw materials for making ink around Lake Maninjau.
 HIGHLIGHTS
 
 Lake Maninjau stores various elements contained in the released material. The elements that make up magnetic minerals are Fe, Si, Ca, Al, K, Ti. The collection of several elements forms the raw magnetic mineral
 Volcanic material contains the mineral ilmenite which in theory can be used as a raw material for making TiO2 pigments, ferrous metals and chemical compounds containing iron. In the industrial field TiO2 is widely used as a paint pigment, additives in the paper-making process, ceramic raw materials, pharmaceutical industry raw materials and TiO2 is also widely used for photoclinic materials
 Superparamagnetic minerals are present in volcanic rock samples resulting from an eruption, the magnetic sensibility values at high frequencies are slightly lower than the magnetic susceptibility values at low frequencies. If there are no superparamagnetic minerals (SP)
 It can be assumed that the ancient volcanic eruptions of Maninjau belong to the type of plinia eruption which is highly exposed from magma with high viscosity or acid magma, the composition of the magma is andesitic to rhyolitic
 
 GRAPHICAL ABSTRACT

Floating cage aquaculture production in Indonesia: Assessment of opportunities and challenges in Lake Maninjau

<abstract> <p>Aquaculture in floating cages in Lake Maninjau has recorded significant growth, even as the largest contributor to total annual aquacultural production in West Sumatra Province. In this study, we assessed the output of floating net cages in Lake Maninjau, Indonesia. We analyzed the characteristics of fish farming, fish fry, feed supply, and production, and the challenges and opportunities for increasing aquacultural production in the future. We used purposive sampling in this study with an interview questionnaire to obtain information from 80 fish-cultivating households in Lake Maninjau. We then used descriptive statistical methods of data analysis. The results showed that in 2018, there were 17596 floating net cages. The majority (n = 33, 41.25%) of fish farmers have 20 to 40 floating net cages per household, and 67.5% (n = 54) are used for tilapia cultivation. We recorded that 77.5% (n = 62) of fingerlings were sourced from private hatcheries. Six companies supply commercial feed pellets in an amount of 2000 tons per month for aquaculture activities. Japfa Comfeed Indonesia Ltd. provides 35% of the feed. The fish species cultivated were Nile tilapia, common carp, giant gourami, Clarias catfish, and pangasius catfish, with gross yields (kg/m<sup>3</sup>/cycle) of 12, 11.5, 10.4, 7.88, and 8.89, respectively. Fish farmers face challenging conditions: poor water quality, mass mortality of tilapia, high fish feed prices and low fish sale prices, and noncash payments. We recommend ensuring the development of floating net cages in Lake Maninjau for a more sustainable future. Therefore, it is necessary to operate as many as 6000 nets to meet guidelines for carrying capacity and cultivation based on the Regional Regulation of Agam Regency Number 5 of 2014 concerning the management of Maninjau Lake, which is accessible proportionally by eight villages. Giant gourami is prioritized for cultivation because it is resistant to poor water quality and high market prices.</p> </abstract>

Herpetofauna of the Maninjau caldera, West Sumatra, Indonesia, with special account to geckos

The field surveys were conducted in the Maninjau Lake region, Sumatera Barat, Indonesia, in February 2020, mainly on the north-eastern slope of the Maninjau caldera at 450–600 m a.s.l. The slopes of the Maninjau caldera are naturally covered by a tropical rainforest that remains quite undisturbed from an altitude of 900 m up to the crater ridge. Natural vegetation of the northern and eastern slopes at altitudes from 450 and 500 to 600 m a.s.l. is replaced by rice plantations or mixed forest gardens. The typical habitat consisted of an evergreen broad-leaved forest on the slopes along a mountain creek and around a waterfall. Herein, we report 11 new species records for the Maninjau caldera; 9 new species records for Agam Regency; 3 new species records for Sumatra and Indonesia and 1 species of Cnemaspis Strauch, 1887 new for science. The morphology of rare and poorly known species of the bent toed gecko, Cyrtodactylus agamensis (Bleeker, 1860) is described for the first time. A high diversity of Cyrtodactylus Gray, 1827 occurs in Indochina and on the Thai-Malay Peninsula (150 species) but only six species in Sumatra. The Malay-Indochinese genus Cnemaspis has a recent spurt of diversity and now reaches eight species in Sumatra and only one species reaches Java. Current gecko diversity in Sumatra comprises 29 species in eight genera. The level of endemism level in geckos is very high and reaches 48%. The herpetofauna of Maninjau Caldera includes 26 amphibian and 46 reptile species. The faunistic core of the West Sumatran herpetofauna consists of Malay-Sundaic, Sumatran endemic, Sunda-Indochinese and widely distributed Oriental elements. The West Sumatran herpetofauna is characterized by the presence of a mutual species with Indochina, Malaysia, east India, Myanmar, the Andaman and Nicobar islands and Sri Lanka, often with disjunction in the huge territory of Indochina; species with continuous distribution from the Indian subcontinent to Papua and Oceania; and generalist species with wide pan-Indopacific distribution.

THE EFFECT OF VARIATIONS OF COMPOSITION OF FELSDPAR AND THE SHELL OF PENSI SHELL (Corbicula Moltkiana) FROM LAKE MANINJAU ON THE FLEXIBILITY OF DENTURE

Utilization of waste pensi shells (Corbicula Moltkiana) in Lake Maninjau has not been fully optimal so that a more economical business is needed. One of them is the use of calcium oxide in pensi shells. Calcium oxide is one of the most commonly used calcium in the manufacture of dentures. This study aims to determine the value of the optimum flexural strength of the denture in order to obtain a higher quality denture material on the pensi shell that can be utilized and which has economic value. The method used is the experimental method. The sample used in this study with a size of 90 mm X 18 mm X 8 mm for testing flexibility / flexural strength. The total samples used in this study were 12 samples for testing the flexibility/flexural strength using a bending testing machine. For the use of pensi shell material, a calcination process was carried out at a temperature of 1000℃ on the pensi shell material and then characterized using XRF to determine the ingredients. The results of the characterization using XRF showed that pensi shells contain calcium elements of 97.121% and about 3% other elements such as Si, Al, P, Ag, Mn and Fe. Then the pensi shell material is mixed with other ingredients such as felsdpar, quartz, and kaolin. The material is mixed and then molded for flexural testing specimens. Based on the test results of this study, the highest flexibility value for denture samples was found in sample 4 with the most variations of pensi shell powder. The highest denture flexibility value is 25.778 MPa with a variation of 30 gram pensi shell powder in sample 4. The lowest denture flexibility value is 5.727 MPa with a variation of 0 gram pensi shell powder in sample 1. This is due to the addition of pensi shell powder. can increase the value of flexibility in dentures. The increase in the flexibility value was influenced by the CaO content obtained from the pensi shell powder.

Effect of Anthropogenic Activity on Benthic Macroinvertebrate Functional Feeding Groups in Small Streams of West Sumatra, Indonesia

Functional feeding groups (FFG) of benthic macroinvertebrates have been used to characterize the condition of aquatic ecosystems, changes in land use, and assess the river health ecosystems. Ranggeh River belongs to a small river that plays a vital role in breeding the native fish of Lake Maninjau (West Sumatra). Agricultural activities and human settlements around the Ranggeh River can threaten life and change the FFG of benthic macroinvertebrates. This study aims to analyze and observe changes in water quality by anthropogenic activities and their impact on FFG benthic macroinvertebrates in a small stream (Ranggeh River). This research was conducted at the Ranggeh River segment from February to August 2019. A sampling of benthic macroinvertebrates was carried out using a Hess sampler on the riffle. This study shows that predators, shredders, and scrapers are still dominant when the Ranggeh River ecosystem is still minimally disturbed by agricultural activities and settlements. However, when agriculture activities and human settlements become more massive, the dominant FFGs are collector-filterers and collector-gatherers. Sedimentation parameters (turbidity and % embeddedness) in the Ranggeh River greatly influence predators, scrapers, and shredders. FFG has excellent potential to be further developed in preparing biocriteria for the effects of agriculture and human settlements.

Assessment of Corbicula moltkiana Growth by Different Methods on Variation of Substrates in Lake Maninjau, West Sumatera, Indonesia

Corbicula moltkiana is a mussel species in Lake Maninjau and one of the targeted fisheries resources in the lake. This study aimed to determine the feasibility of a controlled growth experiment of mollusk biota in describing their natural growth. The assessment was carried out in areas with different habitats in shore lake, namely sand and gravel-stone substrates. A consecutive 12 month- sampling was carried out from June 2013 to May 2104 using a Surber sampler at a 1-3 m depth were used to assess the wild population growth. Moreover, the growth of the controlled population was observed by rearing various sizes of mussels in artificial substrate namely three small baskets which installed in the shore area with 1-3 m depth at each station for four months. Monthly sampling was carried out to measure the shell length. The growth of C. moltkiana on wild population by VBGF methods show that at the gravel-stone substrate was higher, but the growth a controlled population in artificial substrate seemed in the sand substrate was higher than that in the gravel-stone substrate. The growth of aquatic biota in a controlled system (especially C. moltkiana) does not always reflect similar conditions to their wild growth.

Nutrient loading and farm characteristics of giant gourami fish aquaculture systems in Lake Maninjau, Indonesia: basic knowledge of production performance

Background Aquaculture systems for giant gourami, Osphronemus goramy Lacepède (1801), have significantly improved fish production yields and food security in Indonesia. However, these systems also cause serious problems in terms of eutrophication in waterbodies. This study analysed the nutrient loading and farm characteristics of giant gourami in floating cages in Lake Maninjau. Method A total of 20 floating cages were used to record these nutrients in feed supply, female and male juvenile fish, dead fish and harvested fish to estimate nutrient loading. Data on the harvested fish, production cycle, stock number and cage capacity were used to estimate the stocking density, feeding rate, feed efficiency, and net fish yield, and the relationship between feed supply and nutrient loading and farm characteristics was analysed by least squares regression methods. Results A total of 20 floating cages released nutrients into waterbodies at an average rate of 236.27±60.44 kg/cycle for C, 84.52±20.86 kg/cycle for N and 8.70±3.63 kg/cycle for P. On average, fish production for each floating cage (±SD) was 1226±282 kg wet weight/cycle, and the net fish yield was 12.63±2.82 kg/m3/cycle. Survival rates ranged from 86.33 to 95.27%/cycle. The production cycles varied from 160 to 175 days with feed conversion ratios between 1.60 and 1.75, feed conversion efficiencies were between 0.58 and 0.63. The production parameters that had strong relationships with the net fish yield were feed supply (r2=0.960), stocking rates (r2=0.924) and feeding rates (r2=0.961). In contrast, the length of the production cycle was not strongly related to the net fish yield (r2=0.187). Conclusion Nutrient loading from the supplied feed was greater than that from the harvested fish, juvenile fish and dead fish. Increasing the net fish yield in floating cages was better predicted by the stocking densities and feeding levels than by the other factors.

Application of Empirical Bathymetry Method on Sentinel 2A for Measuring Water Depth of Maninjau Lake

Lake Maninjau is a lake formed by volcanic activity. Many human activities occur on the catchment area, but also in exploited waters. This study aims to mapping the depth of the waters in the Lake Maninjau and assess the effect of field sample distribution on the quality results of the image transformation. The data used are satellite imagery Sentinel 2A, results of point survey. The analysis technique uses the normalized difference water index algorithm, sun glint, empirical bathymetry method and linear regression. The result of the research which is has found that variations of distribution into the dispersion of the recording process of the depth of the object represented by cell. The depth of the water from the results of this transformation refers to the measurement sample in the field survey. The maximum depth of the waters is in the range of 107m. Shallow waters are predominantly distributed in the northern region which is the out late of Lake Maninjau. The southern area forms a deep basin. The distribution of this sample is in the form of an empirical bathymetry map and the relationship between the results of field measurements and the transformation with a regression value of 0.769, this indicates the consideration of total and distribution of survey sample is influence on quality of the results of the transformation.

A Great Food for Children Base on Rinuak Shredded Fish (Psilopsis Sp)

Rinuak fish is an endemic fish in Lake Maninjau, Agam Regency, West Sumatra Province. Fresh fish quickly undergoes a process of decay due to changes due to the activity of certain enzymes. The nutritional status of children under five is closely related to food intake. Therefore, to extend the shelf life of rinuak fish, it is necessary to develop rinuak fish into shredded fish. The purpose of this study was to standardize formulas or recipes, to identify the quality, nutritional content, and preference levels of children under five to shredded rinuak. The formula standardization stage was carried out by eight expert validators in the fields of culinary, food, and nutrition. The results found are standard formulas or recipes, which were carried out through a validation process twice with three trials. The results of the quality of shredded rinuak obtained an average score on the color quality which was categorized as good enough, the shape quality was categorized as good enough, the aroma quality was categorized as very good, the texture quality was categorized as good, and the taste quality was categorized as good. The results showed that water content was 8.65%, fat 50.13%, protein 27.53%, carbohydrate 7.62%, ash content 6.57%, and Fe 33.5625 mg/kg. The results of the hedonic test data (preferences) of toddlers for shredded shows that children under five mostly like it

Nutrient loading and farm characteristics of giant gourami fish aquaculture systems in Lake Maninjau, Indonesia: basic knowledge of production performance

Background Aquaculture systems for giant gourami, Osphronemus goramy Lacepède (1801), have significantly improved fish production yields and food security in Indonesia. However, these systems also cause serious problems in terms of eutrophication in waterbodies. This study analysed the nutrient loading and farm characteristics of giant gourami in floating cages in Lake Maninjau. Method A total of 20 floating cages were used to record these nutrients in feed supply, female and male juvenile fish, dead fish and harvested fish to estimate nutrient loading. Data on the harvested fish, production cycle, stock number and cage capacity were used to estimate the stocking density, feeding rate, feed efficiency, and net fish yield, and the relationship between feed supply and nutrient loading and farm characteristics was analysed by least squares regression methods. Results A total of 20 floating cages released nutrients into waterbodies at an average rate of 236.27±60.44 kg/cycle for C, 84.52±20.86 kg/cycle for N and 8.70±3.63 kg/cycle for P. On average, fish production for each floating cage (±SD) was 1226±282 kg wet weight/cycle, and the net fish yield was 12.63±2.82 kg/m 3/cycle. Survival rates ranged from 86.33 to 95.27%/cycle. The production cycles varied from 160 to 175 days with feed conversion ratios between 1.60 and 1.75, feed conversion efficiencies were between 0.58 and 0.63. The production parameters that had strong relationships with the net fish yield were feed supply ( r 2=0.960), stocking rates ( r 2=0.924) and feeding rates ( r 2=0.961). In contrast, the length of the production cycle was not strongly related to the net fish yield ( r 2=0.187). Conclusion Nutrient loading from the supplied feed was greater than that from the harvested fish, juvenile fish and dead fish. Increasing the net fish yield in floating cages was better predicted by the stocking densities and feeding levels than by the other factors.

Identification of Elemental Composition and Heavy Metal Content in Maninjau Lake Sediment Using X-Ray Fluorescence (MNJ 18-41B)

Maninjau Lake is a caldera lake located in Agam, West Sumatra. This lake was formed from the volcanic activity of Mount Maninjau Purba about 60,000 years ago. The volcanic material resulting from the eruption is scattered and deposited in various places, one of which is in lake sediments. Volcanic ash contains various types of elements, including heavy metal elements. This study aims to determine the composition and content of heavy metal in the sediments of Maninjau Lake. The sample analyzed was MNJ 18-41B with a core length of 440 mm, focusing on specimens 148 mm and 376 mm. The selection is a specimen based on the magnetic susceptibility value obtained from the measurement meter susceptibility of the MS2E. Specimen 148 has a value susceptibility low of 2.1 × 10-8 m3/kg, while the 376 specimens have the highest value of susceptibility, the highest 141 × 10-8 m3/kg. The content of sediment elements was determined using the results of X-Ray Fluorescence (XRF) measurements. The measurement results showed that the mineral-forming elements in the sediments of Lake Maninjau were dominated by Si, Fe, Rh, and Zr. In contrast, the highest heavy metal elements are Mn, Fe, Sr, and Rh. Based on the elemental composition and mineral oxide compounds in the sediments of Lake Maninjau derived from volcanic ash.

Fish diversity monitoring in Maninjau Lake, West Sumatra using the eDNA with the next generation sequencing (NGS) technique

Various phenomena in nature and human activities have resulted in the loss of biodiversity, such as freshwater fish in Maninjau lake, West Sumatra, which has declined from year to year. A new method to monitor biodiversity quickly and efficiently is the NGS technique on environment DNA (eDNA). The study aimed to know the NGS technique’s ability and effectiveness to detect multiple species at one time from the water samples of Maninjau Lake. Water was taken from the surface as much as one L with two replications. The sequencing was used to identify species as shotgun metagenomic with universal primers. The results showed that 92 individuals were identified with 56 species from 24 genera, 16 families, and 12 orders. As much as 25% of fishes still cannot be grouped into the valid taxa (unclassified), which is allegedly related to the lack of available information database (NCBI) compared to the sequences obtained. NGS on the eDNA method detected two families (Cyprinidae and Cichlidae), three genera (Oreochromis, Cyprinus, and Xiphophorus), and two species of fish (Oreochromis niloticus and Cyprinus carpio) in Maninjau Lake, which were also previously reported using the conventional method. The native species were not detected in Maninjau lake by the eDNA method allegedly due to not being captured DNA from the collected water samples or the low DNA concentration, which cannot be continued to the PCR process. Thus, several efforts are needed to reduce the limitations in monitoring using the eDNA method to obtain the maximal results. The eDNA method can be a useful tool for monitoring biodiversity. The result can determine the conservation strategies, especially for the fishes in Maninjau Lake, West Sumatra.