Modeling of habitat suitability for sea cucumber ranching in Sintok Island, Karimunjawa National Park, Indonesia

Increasing demand for marine resources, such as sea cucumber, has led to widespread interest in their conservation, one of which is sea ranching. This study sought to identify habitat suitability for sea cucumber Holothuria scabra ranching. The proposed location was Sintok Island, one small island part of Karimunjawa Archipelagos. The HSI (Habitat Suitability Index) model was used to identify potential sites for sea cucumber ranching. Twelve habitat factors were used as input variables for the HSI model: sediment classification, water temperature, salinity, pH, dissolved oxygen, depth, transparency, current, depth, organic matter and chlorophyll-a of the sediment, seagrass density, and tide. The weighting of each habitat factor was defined through the Delphi method. Sediment classification and seagrass density were the most and less important condition affecting the HSI of H. scabra in the different study areas with weighing index of 0.2191 and 0.015 respectively. The HSI of Southern Station (Station 1) was relatively low (0.79-0.81), meaning the site was not suitable for sea ranching of H. scabra. In contrast, the western (Station 2) and the northern part (Station 3) of Sintok Island, were preferable sites, suitable as habitats for restoration efforts in sea ranching.

Structure of Seagrass Community in the Karapyak Beach, Pangandaran Regency, West Java

Karapyak Beach is one of the beaches that has a variety of abundant marine ecosystems. One of the marine ecosystems is seagrass. This study aims to identify the structure of seagrass communities in Karapyak waters based on seagrass species, species density, species frequency, diversity, and uniformity. This research was conducted in February – April 2021. The method used is a survey method with direct observation at each predetermined station using a square transect measuring 1 x 1 m2. While the determination of stations and observation points is done by purposive sampling method. The research location is divided into three stations, each station is divided into five substations (plots), and a 50 m transect line is made perpendicular to the shoreline. Furthermore, the results showed four types of seagrass found in the waters of Karapyak Beach, namely Cymodocea rotundata, Thalassia hemprichii, Halodule pinifolia, Halodule uninervis. The density of seagrass at station I was in the medium category, namely 125 individuals/m2, with a cover percentage of 86%. Then the lowest seagrass density was found at the second station, which was 104 individuals/m2 including the unhealthy category with a cover percentage of 58%. While the highest density score was shown at the third station, namely 144 individuals/m2 with a closing percentage of 94%.

Keanekaragaman Perifiton Daun Lamun Enhalus acoroides dan Cymodocea serrulata di Teluk Awur, Jepara

Ekosistem padang lamun merupakan ekosistem bahari yang memiliki keanekaragaman hayati dan memiliki produktivitas tinggi di perairan dangkal. Adanya keberadaan perifiton yang menempel pada daun lamun diduga dijadikan sebagai faktor penunjang produktivitas primer di kawasan ekosistem lamun. Penelitian ini bertujuan untuk mengetahui kelimpahan perifiton, distribusi perifiton dan hubungan kerapatan lamun terhadap kelimpahan perifiton di Perairan Teluk Awur, Jepara. Penelitian ini menggunakan metode survei dan penentuan lokasi dipilih dengan menggunakan metode sampling purposive method, sedangkan metode pengambilan data lamun mengacu pada metode line transek kuadran. Pengambilan daun lamun untuk pengamatan perifiton menggunakan metode sapuan daun yang selanjutnya diamati dengan menggunakan mikroskop. Nilai kelimpahan perifiton pada daun lamun Enhalus acoroides di Stasiun 1, Stasiun 2, dan Stasiun 3 berturut-turut adalah 105 ind/cm2, 167,5 ind/cm2, dan 101,25 ind/cm2. Sedangkan kelimpahan perifiton pada daun lamun Cymodocea serrulata di Stasiun 1 tidak ada lalu Stasiun 2 dan Stasiun 3 berturut-turut adalah 80 ind/cm2 dan 135 ind/cm2. Kelimpahan tertinggi perifiton terdapat pada jenis lamun E. acoroides diduga karena E. acoroides mempunyai luas penampang daun yang lebih lebar dibandingkan C.serrulata. Perifiton yang mendominasi di lokasi ini berasal dari Kelas Bacillariophyceae. Sebaran perifiton berdasarkan perhitungan indeks morisita yaitu berkelompok dan terdapat hubungan antara kelimpahan perifiton dengan kerapatan lamun. The seagrass ecosystem is a marine ecosystem that has biodiversity and is high productivity in shallow waters. The presence of periphyton attached to seagrass leaves is thought to be used as a primary productivity supporting factor in the seagrass ecosystem. This research aims to determine the periphyton abundance, periphyton distribution and seagrass density relationship towards periphyton abundance in Teluk Awur, Jepara. The survey method and location determination were selected based on purposive sampling method, while the seagrass data collection method refers to the quadrant line transect method. The taking of seagrass leaf for periphyton observation used leaf drainage method was then observed using a microscope. Periphyton abundance value on seagrass leaves of Enhalus acoroides in Station 1, Station 2, and Station 3 are respectively 105 ind / cm2, 167,5 ind / cm2, and 101, 25 ind / cm2. Periphyton abundance in seagrass leaves Cymodocea serrulata in Station 1 was not found while Station 2 and Station 3 are 80 ind / cm2 and 135 ind / cm2 respectively. The highest abundance of periphyton is in the type of seagrass E. acoroides because E. acoroides has a wider leaf cross-sectional area than C. serrulata. Periphyton that dominates the waters of Teluk Awur comes from the Bacillariophyceae class. Periphyton distribution based on the morisita index calculation is clustered and there is a relationship between periphyton abundance and seagrass density.

Pengaruh Nitrat Dan Fosfat dalam Sedimen terhadap Kerapatan Lamun di Jepara

Ekosistem lamun memiliki fungsi ekologis sebagai produsen dan habitat biota (tempat pemijahan biota, daerah mencari makan), melindungi dan menstabilkan garis pantai, serta memainkan peran penting dalam siklus dan pemyimpanan nutrien dan karbon. Ketersediaan nutrien di perairan padang lamun berperan dalam faktor pertumbuhan lamun tersebut sehingga efisiensi daur nutrisi dalam sistemnya menjadi sangat penting untuk memelihara produktivitas primer padang lamun. Hasil penelitian menunjukan bahwa kerapatan lamun total di Teluk Awur sebesar 202,55 ind/m2, sedangkan di Pulau Panjang memiliki kerapatan total sebesar 424.36 ind/m2 dengan rata-rata 50,64 ind/m2 dan 85,67 ind/m2 Pulau Panjang memiliki kerapatan yang lebih tinggi dibandingkan di Teluk Awur. Hasil Kandung nitrat dan fosfat pada sedimen di Teluk Awur didapatkan masing-masing dengan rata-rata 7,67 ppm dan 25,61 ppm, sedangkan kandungan nitrat dan fosfat sedimen di Pulau Panjang didapatkan masing-masing dengan rata-rata 6,38 ppm dan 24,44 ppm. Analisis regresi korelasi menunjukan bahwa di Teluk Awur memiliki keeratan korelasi negatif dan kuat antara nitrat sedangkan dengan fosfat memiliki keeratan korelasi positif dan sedang, kemudian pada Pulau Panjang menunjukan hubungan positif yang kuat dan sangat kuat antara nitrat dan fosfat sedimen terhadap kerapatan lamun. The seagrass ecosystem has an ecological function of the seagrass ecosystem as a producer and habitat for biota (spawning grounds for biota, foraging areas), protects and stabilizes shorelines, and plays an important role in cycling and storing nutrients and carbon. The availability of nutrients in the seagrass beds plays a role in the growth factor of the seagrass so that the efficiency of the nutrient cycle in the system is very important to maintain the primary productivity of the seagrass beds.The results showed that the total seagrass density in Teluk Awur was 202.55 ind/m2, while in Panjang Island it had a total density of 424.36 ind/m2 with an average of 50.64 ind/m2 and 85.67 ind/m2. higher density compared to Teluk Awur Results Nitrate and phosphate content in sediments in Teluk Awur were obtained respectively with an average of 7.67 ppm and 25.61 ppm. Meanwhile, the nitrate and phosphate content of sediment in Panjang Island were obtained with an average of 6.38 ppm and 24.44 ppm, respectively. The results of the correlation analysis of the correlation between nitrate and phosphate content of sediments on seagrass density in Teluk Awur have a negative and strong relationship between nitrate while phosphate has a positive and moderate relationship. In Panjang Island, the results of the correlation analysis showed a positive and strong relationship between nitrate, while phosphate had a positive and very strong relationship between sediment and seagrass density.

Perbandingan Perifiton pada Thalassia hemprichii dan Cymodocea rotundata di Perairan Teluk Awur, Jepara

Keanekaragaman jenis lamun dan struktur morfologi yang cukup besar pada Thalassia hemprchii dan Cymodocea rotundata memungkinkan ditumbuhi perifiton yang dapat meningkatkan produktivitas primer. Penelitian ini bertujuan untuk mengetahui kelimpahan perifiton pada T. hemprichii dan C. rotundata di Perairan Teluk Awur, Jepara. Penelitian dilaksanakan pada Bulan Juli 2020 menggunakan metode survei dan penentuan lokasi dipilih dengan menggunakan metode purposive random sampling, sedangkan metode pengambilan data lamun dengan metode line transect quadrant yang mengacu pada metode LIPI. Pengambilan daun lamun untuk pengamatan perifiton menggunakan metode sapuan daun yang selanjutnya diamati dengan menggunakan metode sensus yaitu pengamatan total dengan alat sedgwick rafter di bawah mikroskop. Nilai kelimpahan perifiton pada daun lamun T. hemprichii sebesar 27.635 ind/cm2. Sedangkan kelimpahan perifiton pada daun lamun C. rotundata sebesar 23.015 ind/cm2. Kelimpahan tertinggi perifiton terdapat pada jenis lamun Thalassia hemprichii, hal ini diduga karena Thalassia hemprichii mempunyai penampang daun yang lebih lebar. Perifiton yang mendominasi di Perairan Teluk Awur berasal dari Kelas Bacillariophyceae, diduga karena kelas ini memiliki kemampuan melekat pada substrat yang baik. Berdasarkan perhitungan Indeks Morisita maka diketahui bahwa sebaran perifiton di Perairan Teluk Awur didominasi pola sebaran mengelompok. Kelimpahan perifiton dengan kerapatan lamun di Perairan Teluk Awur memiliki hubungan cukup erat.The considerable diversity of seagrass species and morphological structures in Thalassia hemprchii and Cymodocea rotundata allows the growth of periphyton which can increase primary productivity. This study aims to determine the abundance of periphyton and its distribution patterns in the waters of Teluk Awur, Jepara. The study, which was conducted in July 2020, used a survey method and the location was selected using the purposive sampling method, while the seagrass data collection method used the line transect quadrant method which refers to the LIPI method. Seagrass leaves were collected for periphyton observations using the leaf sweep method, which was observed using the census method, namely total observation using the sedgwick rafter under a microscope. The abundance value of periphyton in Thalassia hemprichii seagrass leaves was 27,635 ind/cm2. While the abundance of periphyton in seagrass leaves of Cymodocea rotundata was 23,015 ind/cm2. The highest abundance of periphyton is found in the type of seagrass T. hemprichii, this is presumably because T. hemprichii has a wider leaf cross section. The dominant periphyton in Teluk Awur waters comes from the Bacillariophyceae class, presumably because this class has good adherence to the substrate. Based on the calculation of the Morisita Index, it is known that the distribution of periphyton in the waters of Teluk Awur, Jepara is dominated by a clustered distribution pattern. The abundance of periphyton and seagrass density on Parang Island is closely related.

When “Blue Carbon” turns white: Isotopic evidence of calcification-driven CO2 emissions in a carbonate seagrass meadow

<p>Seagrasses are often considered important players in the global carbon cycle, due to their role in sequestering and protecting sedimentary organic matter as “Blue Carbon”.  However, in shallow calcifying systems the ultimate role of seagrass meadows as a sink or source of atmospheric CO<sub>2</sub> is complicated by carbonate precipitation and dissolution processes, which produce and consume CO<sub>2</sub>, respectively.  In general, microbial sulfate, iron, and nitrate reduction produce total alkalinity (TA), and the reverse reaction, the re-oxidation of the reduced species, consumes TA. Therefore, net production of TA only occurs when these reduced species are protected from re-oxidation, for example through the burial of FeS<sub>x</sub> or the escape of N<sub>2</sub>.  Seagrasses also affect benthic biogeochemistry by pumping O2 into the rhizosphere, which for example may allow for direct H2S oxidation.</p><p>Our study investigated the role of these factors and processes (seagrass density, sediment biogeochemistry, carbonate precipitation/dissolution, and ultimately air-sea CO<sub>2</sub> exchange), on CO<sub>2</sub> source-sink behavior in a shallow calcifying (carbonate content ~90%) seagrass meadow (Florida Bay, USA), dominated by Thalassia testudinum. We collected sediment cores from high and low seagrass density areas for flow through core incubations (N<sub>2</sub>, O<sub>2</sub>, DI<sup>13</sup>C, sulfide, DO<sup>13</sup>C flux), solid phase chemistry (metals, PO<sup>13</sup>C, Ca<sup>13</sup>C<sup>18</sup>O<sub>3</sub>, AVS: FeS + H<sub>2</sub>S, CRS: FeS<sub>2</sub> + S<sup>0</sup>), and porewater chemistry (major cations, DI<sup>13</sup>C, sulfide, <sup>34</sup>S<sup>18</sup>O<sub>4</sub>). An exciting aspect of this study is that it was conducted inside the footprint of an Eddy Covariance tower (air-sea CO<sub>2</sub> exchange), allowing us to directly link benthic processes with CO<sub>2</sub> sink-source dynamics.</p><p>During the course of our week long study, the seagrass meadow was a consistent source of CO<sub>2</sub> to the atmosphere (610 ± 990 µmol·m<sup>-2</sup>·hr<sup>-1</sup>).  Elevated porewater DIC near 15 cmbsf suggests rhizosphere O<sub>2</sub> induced carbonate dissolution, while consumption of DIC in the top 5-10 cm suggests reprecipitation.  With high seagrass density, enriched δ<sup>13</sup>C<sub>DIC </sub>in the DIC maximum zone (10-25 cm) suggests continual reworking of the carbonates through dissolution/precipitation processes towards more stable PIC, indicating that seagrasses can promote long-term stability of PIC.  We constructed a simple elemental budget, which suggests that net alkalinity consumption by ecosystem calcification explains >95% of the observed CO<sub>2</sub> emissions.  Net alkalinity production through net denitrification (and loss of N<sub>2</sub>) and net sulfate reduction (and subsequent burial of FeS<sub>2</sub> + S<sup>0</sup>), as well as observed organic carbon burial, could only minimally offset ecosystem calcification.   </p>

The Impact of Tsunami on Seagrass Ecosystem in Tanjung Lesung, Banten, Indonesia

The Sunda Strait Tsunami (end of 2018) has an impact on the seagrass ecosystem in Tanjung Lesung. This paper described the seagrass ecosystem’s changes after the tsunami disaster. Sentinel-2 satellite image processing in 2018 and 2019 was used to see changes in the seagrass area. The field data were collected from May–July 2019, including the types of seagrass ecosystems based on data seagrass existence, density and biomass. Then, the seagrass sample was analyzed biomass after the tsunami disaster. The results showed that the data from 2018 – 2019 showed decreased seagrass area from 105.86 to 77.07 ha. Seagrass density dropped quite dramatically, and the species of Halodule uninervis was no longer found. The ratio of after tsunami BG/AbG dry biomass has doubled compared to before the tsunami, which indicates the seagrass's lower biomass is higher than the upper part allegedly due to tsunami impacts. Based on the results obtained, it can be concluded that the seagrass ecosystems changed and disrupted by the tsunami. Keywords: Seagrass, Tanjung Lesung, Tsunami, Sentinel-2

Density and Biomass of Seagrass Beds and Its Threats on Lamongan Regency

This study aimed to determine the density of seagrass species, seagrass biomass, and threats faced by seagrass communities in the Coastal District of Lamongan. The study was conducted from August to November 2019 in three coastal villages of Lamongan Regency, namely Tunggul Village (Station 1), Kranji Village (Station 2), and Banjarwati Village (Station 3). Furthermore, the stages of the study consisted of preparation, data collection on density, threat data, seagrass stand samples, sample processing, and data analysis. The results showed that the total density of seagrass species at Stations 1, 2, and 3 was 160 stands/m2, 172 stands/m2, and 185 stands/m2, respectively. Moreover, the total biomass of seagrass at Stations 1, 2, and 3 was 4633 g/m2, 2136 g/m2, and 9234 g/m2, respectively. In addition to seagrass species, seagrass density values also affected seagrass biomass. As development progresses in Lamongan Regency, it is known that the biggest threat of seagrass communities in the study site is human activity (anthropogenic), especially the anchor ships when anchored and the use of coastal areas as tourist areas. This occasion often cleans up seagrass communities because they are deemed unfit to be enjoyed tourism sector.

Kandungan Nitrat dan Fosfat dalam Air Pori Sedimen dan Kolom Air di Daerah Padang Lamun Perairan Pantai Prawean, Bandengan, Jepara

ABSTRAK : Secara alamiah konsentrasi zat hara dalam perairan bervariasi untuk masing-masing bentuk senyawanya, termasuk nitrat dan fosfat. Lamun berperan penting terhadap sumbangan nutrien di perairan dengan hasil dekomposisi serasah lamun oleh mikroorganisme pengurai. Fungsi sistem lamun terletak pada pemahaman faktor-faktor yang mengatur produksi dan dekomposisi bahan organik serta efisiensi daur nutrisi dalam sistemnya. Penelitian ini bertujuan untuk mengetahui kandungan nitrat dan fosfat air pori sedimen dan kolom air serta mengetahui jenis dan jumlah kerapatan lamun yang terdapat di perairan Pantai Prawean Bandengan Jepara. Metode penelitian ini menggunakan analisis deskriptif. Analisa kandungan nitrat menggunakan metode analisis SNI 06-6989.31-2005 dan fosfat menggunakan metode analisis BP2-MU-A-08. Pengamatan lamun menggunakan transek kuadrat 50x50cm menurut panduan LIPI. Kandungan nitrat air pori sedimen berkisar 1,85 – 2,82 mg/l, tergolong sedang. Sedangkan kandungan nitrat kolom air berkisar 0,63 – 1,09 mg/l, tergolong rendah. Kandungan fosfat pada air pori berkisar 0,09 – 0,15 mg/l, tergolong sangat subur. Sedangkan kandungan fosfat kolom air berkisar 0,02 – 0,04 mg/l, tergolong cukup subur. Jenis lamun yang ditemukan pada lokasi penelitian sebanyak 4 spesies yaitu Enhalus accoroides, Thalassia hemprichii, Cymodocea serullata, dan Cymodocea rotundata. Kerapatan lamun tertinggi di stasiun 2 sebanyak 132 tegakan/m2 (rapat) sedangkan stasiun 1 sebanyak 95 tegakan/m2 (agak rapat) dan stasiun 3 sebanyak 123 tegakan/m2 (agak rapat). Lamun jenis Cymodocea serullata memiliki dominansi tertinggi pada setiap stasiun. ABSTRACT : Naturally the concentration of nutrients in the waters varies for eachthe form of its compounds, including nitrates and phosphates. Seagrass plays an important role in the contribution of nutrients in waters with the result of decomposition of seagrass litter by decomposing microorganisms. The function of the seagrass system lies in understanding the factors that govern the production and decomposition of organic matter and the efficiency of nutrient cycling in the system. This research aims to determine the content of nitrate and phosphate in sediment pore water and water columns in the seagrass beds of Prawean Coast waters Jepara and determine the type and the amount of seagrass density. This research method uses descriptive analysis. Nitrate content analysis using SNI 06-6989.31-2005 and phosphate analysis using BP2-MU-A-08. Seagrass observations using the Transect squared 50x50cm according to the LIPI guidelines. The content of nitrates sediment pore water in the seagrass beds of Prawean Coast ranges from 1,85 to 2,82 mg/l, while the content of nitrate in water column ranges from 0,63 – 1,09 mg/l. The content of phosphate in pore water ranges from 0,09 – 0,15 mg/l, while the phosphate content of the water column ranges from 0,02 to 0,04 mg/l. Four types of seagrass found were Enhalus accoroides, Thalassia hemprichii, Cymodocea serullata, and Cymodocea rotundata. The highest seagrass density at station 2 was 132 stands/m2, while the station 1 was 95 stands/m2 and station 3 was 123 stands/m2. Seagrass type Cymodocea Serullata has the highest dominance at each station.Kata Kunci : Nitrat, Fosfat, Air Pori Sedimen, Kolom Air, Lamun.