Seagrass Cover Research Articles

KAJIAN PERBANDINGAN PERTUMBUHAN IKAN BARONANG (SIGANUS CANALICULATUS) DALAM KERAMBA JARING DASAR PADA KONDISI PADANG LAMUN YANG BERBEDA DI PULAU LANTANG PEO KABUPATEN TAKALAR

Muh. Aryan R Suci. Growth of Baronang Fish (Siganus canaliculatus) in Basic Net Cages in Different Seagrass Conditions on Lantang Peo Island, Takalar Regency. Lantang Peo Island which is one of the islands which is covered by several types of seagrass. Data collection was carried out from September to October 2016 at the Lantang Peo estuary. The first treatment is observation of density, cover and identification of seagrass. The second treatment is measuring water quality and the last one is measuring the weight and length of the baronang fish. Observation of seagrass species obtained Enhalus accoroides and Thalassia hempichii species. The total density of seagrass at Station I was 47 (teg / m2) 10.03% cover of seagrass, 70 (teg / m2) density of seagrass at Station II was 17.12% and the total density of seagrass at Station III was 90 (teg / m2) 18.13%. Observation of the absolute growth of baronang fish weight at station I of 1 gr. At station II the absolute weight growth of fish is 3 gr and at station III the absolute weight growth of fish is 5 gr. Observations of the absolute length increase of fish at Station I were 1 cm, the absolute length increase of fish at Station II was 2 cm and the absolute length increase of fish at Station III was 3 cm. This difference occurs due to the different density structure of the seagrass at each station.

Seagrass coverage and associated fauna at Gaya Island, Sabah, Malaysia: A pilot seagrass transplantation

Seagrasses provide a range of marine ecosystem services. These include coastal protection, biodiversity, provision of food for various organisms, breeding and nursery habitats for many marine species, and carbon storage. Increasing anthropogenic pressures have contributed to the decline of seagrass habitats. Transplantation is one of the solutions to increase seagrass coverage and resilience. What is often overlooked, however, is the ability of this tropical ecosystem to attract and support faunal assemblages that may impinge on the success of the transplantation. A pilot study on seagrass transplantation at Gaya Island (Kota Kinabalu, Sabah) was intended for observing its stability and species of fauna that develop association with this vegetation. The study covered the southwest and northeast monsoons. Mixed seagrass species were planted on approximately 50% of 30 m 2 transplantation areas. Monitoring of the planted seagrass was carried out in five phases (T1-T5) from September 2016 to April 2018. Weekly observations were made by SCUBA diving. Identification of associated fauna was done on the spot and was based on morphological characteristics. During the T1 (September to December 2016) the seagrass coverage was reduced to 41% due to strong waves generated by the northeast monsoon. However, the seagrass coverage increased ( 66 %) during the southwest monsoon (T2 - T4) in 2017. In early 2018 (T5), the seagrass coverage again reduced (about 18%) due to strong waves but recovered again at the end of the monitoring period (April 2018). A total of 30 species of fauna that were identified consisted of 9 resident and 21 non-resident species. Physical structure of transplanted seagrass created a microhabitat, and increased the food availability and abundance, which attracted many species of different trophic levels.

Struktur Komunitas dan Sebaran Lamun di Pulau Soop - Kota Sorong

Penelitian ini bertujuan untuk menganalisis jenis dan komposis lamun, penutupan lamun, kerapatan jenis lamun, dan sebaran lamun di Perairan Pulau Soop Kota Sorong-Papua Barat. Metode penelitian adalah eksploratif, yang mana pengambilan data keragaman jenis, komposisi dan kerapatan dilakukan menggunakan transek garis. Pengambilan data dengan Transek garis yang dilakukan pada setiap stasiun dengan cara posisi tegak lurus dengan garis pantai sepanjang setiap 10 m. Setiap transek garis dilakukan pencatatan data pada setiap 10 m tersebut, yang dimulai dari tepi pantai sampai tubir atau kedalaman tertentu. Data primer meliputi jenis lamun, tipe substrat, kerapatan, dan estimasi tutupan serta titik koordinat luasan dan titik pengambilan sampel. Kemudian data di analisis dan dibuatkan dalam bentuk peta dengan menggunakan software Arc-gis 10.6. Berdasarkan hasil penelitian di Perairan Pulau Soop terdapat 7 jenis lamun yaitu yaitu jenis Syringodium isoetifolium, Thalassia hemprici, Cymodocea serrulate, Thalassodendron ciliatum, Halophila ovalis, Enhalus acoroides dan Halodule uninervis. Penutupan lamun tertinggi di stasiun penelitian sebelah Utara perairan pulau Soop sebesar 51,58%, sedangkan penutupan lamun tertinggi di stasiun penelitian sebelah Selatan pulau Soop sebesar sebesar 38.35%. Luas sebaran lamun di sebelah utara dan selatan Perairan Pulau Soop sekitar 2.665.00 m2.

Increasing habitat complexity enhances crab density: A case study from Thailand

AbstractThe problem of seagrass degradation in Southeast Asia region, which harbors some of the greatest marine biodiversity in the world, is increasing due to coastal development and the lack of efficient management. These factors have caused the decline of marine life and have impacted local fisheries. The present study investigated the species, sizes and abundance of swimming crabs in areas of differing seagrass cover at Koh Tha Rai in the Gulf of Thailand. Seagrass cover and crab populations were investigated on May 2006, September 2010 and August 2017. The results showed concomitant change in seagrass cover and the dominant crab species, Thalamita crenata. Seagrass increased from 27.69 ± 5.08% (mean ± SE) to 58.89 ± 5.61% at the low cover site between May 2006 and July 2017, while T. crenata abundance increased 10‐fold (p ≤ .0001). This study highlights the importance of conservation and the importance of seagrass in terms of providing ecosystem services and habitat/refuge for marine benthos in the region.

Seagrass Potential as Supporting Ecotourism in Sibu Island, Subdistrict North Oba, North Maluku Province

Seagrass Ecotourism is a tourism activities based on the ecosystem of seagrass. Component of seagrass consist of vegetation and biota that associated with the seagrass. The purpose of this research is to understand the condition biophysics of seagrass (Types of seagrass, Cover of seagrass, fish, makrozoobenthos, types of substrat, water brightness, the depth of the seagrass) and to establish the suitability of seagrass to support nautical ecotourism. This research have been done in Sibu island, Guraping village, north oba district, Tidore city for 6 month from April – September 2020. The method that used is a survey method consist of direct measuring of types seagrass, cover of seagrass, fish, makrozoobenthos, types of substrat, water brightness, the depth of the seagrass. The data analysis includes percentage of cover seagrass and the suitability index of seagrass ecotourism. The result of the biophysical study were obtained are 8 types of seagrass, cover of seagrass (51,04- 92,71%), fish (12 types), makrozoobenthos (17 types), brightness (77-100%), substart (sand, muddy sand, mud) flow speed (0,01- 0,06 m/dt) and the depth of the seagrass (1-2,5 m). Sibu island could be developed as a region of Seagrass Ecotourism with index suitability tourism (IKW) station 1,3,4 and for the whole are located in category S1 (very suitable) and station 2 is in the suitable category.

Long-term changes in seagrass and benthos at Banc d’Arguin, Mauritania, the premier intertidal system along the East Atlantic Flyway

The benthic communities of soft-sediment intertidal ecosystems trophically underpin the migration of birds and fish. Within the East Atlantic Flyway, along the coast of West-Africa, the intertidal mudflats of Banc d’Arguin, Mauritania, host over 2 million migratory waterbirds. Despite the protected status of the Banc d’Arguin, geographical remoteness and seemingly benign human exploitation, we show that large changes have taken place in the intertidal benthic macrofauna across an interval of 28 years. We compared the results of two comparable and spatially comprehensive large-scale benthic surveys in 1986 and 2014. Over this time, the benthos changed from a diverse community to one dominated by a few species of bivalve, with a loss of polychaete worms. The change was associated with a twofold increase in the seagrass cover. Our results suggest that the intertidal habitats of Banc d’Arguin have altered markedly over the last three decades and the estimated benthic secondary production has decreased by a factor of four. These shifts in community structure and production may have contributed to declines in some benthivorous migratory shorebirds.

Changes in within-canopy environmental conditions and the population structure of the speckled scallop associated to localized loss of above-ground seagrass cover

The three-dimensional structure provided by seagrasses facilitates diverse communities through the provision of refuge from predators, foraging opportunities, and the amelioration of physical stress. The effects of seagrass structural complexity on associated communities have been linked to seagrass shoot biomass and density, often using mesocosm experiments that cannot incorporate naturally occurring physical conditions. Here, we manipulate seagrass cover in the field to identify the short-term and local effects of the loss of Zostera marina (eelgrass) on the physical conditions under the canopy and on the size distribution and mortality of a common bivalve, the scallop Argopecten circularis. Compared to intact eelgrass (100% cover), plots with 50% cover or no cover (100% bare sediment) experienced significant increases of average daily light and temperature. Changes in scallop relative mortality were associated to the reduction in eelgrass cover, while the decrease in scallop size was associated to changes in light and temperature after eelgrass trimming. These results emphasize the importance of seagrass cover for mediating the environmental conditions under the canopy and potentially modulating biological interactions of associated invertebrates.

Cover loss in a seagrass Posidonia oceanica meadow accelerates soil organic matter turnover and alters soil prokaryotic communities

Carbon stocks in coastal vegetated ecosystems account for half of the carbon in marine sediments and soils. Disturbance in these ecosystems can release vast amounts of carbon through mineralization, depending on poorly understood factors, such as soil organic matter (SOM) quality and environmental factors. The meadows of the seagrass Posidonia oceanica, which is the species with the larger carbon stocks, are currently under threat. The aim of this study was to determine the impact of cover loss on the SOM and microbial community composition in a P. oceanica meadow. For this purpose, soil cores were taken in dead, degraded and healthy areas in the same meadow. Cores were analyzed for total, inorganic and organic carbon and nitrogen contents, as well as for molecular SOM composition by analytical pyrolysis (<2 mm fraction). Bacteria and archaea communities were assessed by 16S rRNA gene metabarcoding. The results showed the mineralization of polysaccharides and guaiacyl and syringyl lignin and a selective preservation of p-hydroxybenzoic acid moieties and methylene chain compounds. Soil depth and plant cover showed significant effects on microbial richness and diversity. Spatial variations in SOM inputs and microbial community composition between cores highlighted the importance of intra-meadow variability. Cover loss resulted in a release of soil organic carbon (1.8 fold decrease) and the boost of archaeal communities in the rhizosphere, whereas no effect was found in deeper layers. Our study demonstrates that seagrass cover loss enhances SOM mineralization and highlights the importance of soil stabilization against erosion to avoid the release of millenary SOM stocks.

Change-mapping of estuarine intertidal seagrass (Zostera muelleri) using multispectral imagery flown by remotely piloted aircraft (RPA) at Wharekawa Harbour, New Zealand

This research assesses a survey method for measuring the change in density of intertidal estuarine seagrass (Zostera muelleri) at Wharekawa Harbour, New Zealand, using an autonomous remotely piloted aircraft fitted with a narrowband multispectral camera. Image classification was modelled using the random forest classifier trained with ground observation data sourced from 63 photographed quadrat stations upon three parallel transect lines. Seagrass coverage in the georeferenced and rectified ground photography was estimated by visual interpretation on a three-tier (low, medium and high) density scale, then exact leaf area additionally calculated from digitised seagrass leaf coverage visible in rectified ground photography. Three replicate aerial surveys across four months were conducted to compare predicted change in seagrass density with actual measured change, during austral summer growth and autumn decline. Classification of the resulting image mosaic (2.5 cm pixel size) achieved up to 90–93% overall accuracy across multiple surveys when attributing density class, 93–96% accuracy for prediction of seagrass presence, and 81–91% in terms of detection of seagrass on the ground. Change-maps allow regions of growth and decline to be visualised. Correlation (r) between actual and predicted change for 48 independent test grid squares was 0.89 and 0.61 for the summer and autumn change periods respectively. Rapid visual interpretation of classification end-member classes yielded change measurement equivalent to that of accurately measured seagrass leaf area. The research demonstrates that RPA survey using a multispectral camera is viable for monitoring change in seagrass condition.

Sentinel-2 remote sensing of Zostera noltei-dominated intertidal seagrass meadows

Accurate habitat mapping methods are urgently required for the monitoring, conservation, and management of blue carbon ecosystems and their associated services. This study focuses on exposed intertidal seagrass meadows, which play a major role in the functioning of nearshore ecosystems. Using Sentinel-2 (S2) data, we demonstrate that satellite remote sensing can be used to map seagrass percent cover (SPC) and leaf biomass (SB), and to characterize its seasonal dynamics. In situ radiometric and biological data were acquired from three intertidal meadows of Zostera noltei along the European Atlantic coast in the summers of 2018 and 2019. This information allowed algorithms to estimate SPC and SB from a vegetation index to be developed and assessed. Importantly, a single SPC algorithm could consistently be used to study Z. noltei-dominated meadows at several sites along the European Atlantic coast. To analyze the seagrass seasonal cycle and to select images corresponding to its maximal development, a two-year S2 dataset was acquired for a French study site in Bourgneuf Bay. The potential of S2 to characterize the Z. noltei seasonal cycle was demonstrated for exposed intertidal meadows. The SPC map that best represented seagrass growth annual maximum was validated using in situ measurements, resulting in a root mean square difference of 14%. The SPC and SB maps displayed a patchy distribution, influenced by emersion time, mudflat topology, and seagrass growth pattern. The ability of S2 to measure the surface area of different classes of seagrass cover was investigated, and surface metrics based on seagrass areas with SPC ≥ 50% and SPC ≥ 80% were computed to estimate the interannual variation in the areal extent of the meadow. Due to the high spatial resolution (pixel size of 10 m), frequent revisit time (≤ 5 days), and long-term objective of the S2 mission, S2-derived seagrass time-series are expected to contribute to current coastal ecosystem management, such as the European Water Framework Directive, but to also guide future adaptation plans to face global change in coastal areas. Finally, recommendations for future intertidal seagrass studies are proposed.

Potensi Sumberdaya Lamun Untuk Mendukung Pengembangan Wisata Di Pantai Mengiat Nusa Dua, Bali

Seagrasses have functions and roles as primary producers, biota habitats, bottom seawater stabilizers, sediment catchers, and nutrient recyclers. With the function of seagrass as a habitat of biota, it can provide economic opportunities to be utilized as a marine tourism, especially marine ecotourism. Marine ecotourism is a concept of sustainable use of coastal resources with environmental service system that prioritizes coastal natural resources as an object of service. This study aimed to identify the seagrass potency ecologically and socially and to formulate the seagrass management strategies to support tourism development in Nusa Dua. This study was conducted from January-March 2017 using observation and interview method. Observation method was used to define the condition of seagrass, fish species, and environmental parameters. Then Interview method was used to know social conditiion of Mengiat Beach and analyzed by SWOT to formulate the seagrass management strategies. The result showed, there were 6 species, i.e., Halophila ovalis, Cymodocea Halodule pinifolia rotundata, Syringodium isoetifolium, Thalassia hemprichii, and Thalassodendron ciliatum. The percentage of seagrass coverage at 5 stations tend to be low (5,639%-47,49%). Based on Tourism Suitability Indexes, Mengiat Beach in Nusa Dua is suitable (S2) for tourism activities with value 75,08%. The priority strategies are formulated from the SWOT matrix is applying under water garden in seagrass base on tourism planning.

Identification and composition of fish types in the Youtefa bay tourism area

This study aims to identify and determine the composition of fish species. Sampling was carried out from July 2019 to January 2020 in Youtefa Bay. Fish sampling was conducted by using gill nets. Fishes were caught once in each month during the research period. The result showed of 562 individuals in 53 species of 26 families. Hypothermia barnesi (14,77%); Mugil sp. (12,46%); Acanthurus auranticavus (6,23%); Hemirhamphus far (6,05%); Lutjanus carponotatus (4,09%) and Gerres erythrourus (3,92%). The number and type of fish caught are influenced by seagrass and mangrove ecosystems. The number of fish in each site was affected by the substrate, brightness, and the percentage of seagrass bed coverage; the higher percentage of brightness and seagrass coverage, the higher number of fish found.

The role of women in the utilization of Enhalus acoroides: livelihoods, food security, impacts and implications for coastal area management

Coastal and island communities depend heavily on marine resources for their food and income. During the west monsoon (September to February), fishermen rarely go to sea, and their activities are limited to the small-scale fisheries, including gleaning the Enhalus acoroides fruits. Participants in this small-scale fishery sector are mainly women; with little or no skill required, these gleaners are often overlooked by the district level fisheries-related census. This case study focused on the role of coastal women with different levels of knowledge and utilization of E. acoroides in three cities/districts of South Sulawesi. This study aimed to determine the contribution of E. acoroides fruit collection to coastal community livelihoods and food security, to identify the impacts, and to seek alternative solutions for seagrass management. Qualitative methods were used to gather information on E. acoroides fruit collection, fishery knowledge, livelihood contributions, perceptions of seagrass condition, and alternative management solutions. Around 90% of E. acoroides fruit collectors were women aged between 30 to 80 years old. Women contribute greatly to livelihoods and food security in coastal areas because they play dominant roles in household affairs and the sale of fishery products. Unfortunately, the methods currently used for collecting E. acoroides fruit can be destructive and may have contributed to the decline in seagrass cover. However, prohibiting the collection of E. acoroides would not be an appropriate solution. A win-win solution is needed to empower women while simultaneously managing seagrass ecosystems sustainably.

Comparison of seagrass cover from multi-scale imagery

Mapping of seagrass bed can be done by using different characteristics of satellite images data such as Landsat-8 and Sentinel-2. However, there has been no research compared to the results from those images in Indonesia. This study aims to analyze and compare spatially the condition of seagrass bed from Landsat-8 and Sentinel-2 imagery covered Kodingareng Lompo island. Spatially sharpened (Pan-sharpening) Landsat-8 imagery from 30 to 15 meters resolution in four spectral bands (visible and NIR) were used in this case. The results showed the four classes seagrass cover percentage consisted of sparse class (0 – 25%), medium-class (26 – 50%), dense class (51 – 75%), and very dense class (76 – 100%). Classification of seagrass cover class and water column correction (Depth Invariant Index) value differed between the two imageries. Accuracy test of seagrass cover classification from Landsat-8 (88.1%) and Sentinel-2 (89.2%) were both suitable to use since they were higher than the standard value (>85%). Differences in the characteristics of both images cause differences in the results of the seagrass cover classification.

Decline in seagrass carbon uptake on Bonebatang Island, Spermonde Archipelago, Indonesia during the period of 2001-2017

The activities of coastal and small islands communities can have an impact on the condition of the adjacent aquatic ecosystems. The magnitude of the impact depends on the type and intensity of the activities carried out. One ecosystem that is prone to be affected is the seagrass ecosystem due to its presence in shallow waters and proximity to the coast. The study was conducted to examine changes in seagrass carbon uptake on Bonebatang Island over a period of 16 years from 2001 to 2017. Estimation of carbon uptake of seven species of seagrasses, i.e., Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Halodule uninervis. Halophila ovalis, Halophila minor, and Syringodium isoetifolium were carried out using the oxygen change method that utilized clear bottles. The percentage of seagrass coverage was calculated using a 50cm x 50cm plot. The average composition of seagrass species from all plots and the capability of each seagrass species to uptake carbon was used as a basis to estimate the capability of seagrass to uptake the carbon per unit area. Changes in carbon uptake were determined using an approach that estimates changes in the seagrass bed areas. Landsat image analysis was used to estimate the area of seagrass in 2001, 2009, and 2017. The results showed that the area of seagrass beds in the period of 2001-2017 decreased by 8.62 ha, from 37.08 ha in 2001 to 28.46 ha in 2017 or decreased by approximately 1.54% per year. As a result of this diminishing in the area, carbon uptake by seagrasses was estimated to decrease by 19.67 MgCO2 per year from 79.62 MgCO2 per year in 2001 to 59.95 MgCO2 per year in 2017. The average decrease in a year reached 1.23 MgCO2.

INVESTIGATING THE EFFECTS OF RIVER DISCHARGES ON SUBMERGED AQUATIC VEGETATION USING UAV IMAGES AND GIS TECHNIQUES

Abstract. One of the major factors controlling the distribution and abundance of marine submerged aquatic vegetation (SAV) is light availability. Reduced water clarity due to sediment loading from rivers greatly affects the health and coverage of seagrasses and seaweeds. Monitoring SAV using unmanned aerial vehicles (UAV) has been getting attention because of its cost-effectiveness and ease of use. In this research, a low-cost UAV was utilized to assess the impacts of river discharges on SAV in Busuanga Island, Philippines. Linear regression was performed to determine the effectivity and accuracy of UAV-based percent cover estimation compared to established field survey methods of monitoring SAV. Water quality was estimated in the study area by performing spatial interpolation methods of in situ measurement of turbidity, chlorophyll, temperature, salinity, and dissolved oxygen using a multi-parameter water quality sensor. Current velocity and tidal fluctuations were monitored using bottom-mounted sensors deployed near the river mouth and in seagrass and seaweed areas with relatively good water clarities. Four stations were surveyed using automated UAV missions which were flown simultaneously with field observations. Each station surveyed has varying distances from the river mouth. Results from the classification of the UAV data and field survey show that SAV is more abundant as the distance from the river mouth increases and the turbidity decreases. Classification overall accuracies of UAV orthophotos ranging from 87.91–93.41% were achieved using Maximum Likelihood (ML) Classification. Comparison of field-based and UAV-based survey of percent cover of seagrasses show an overestimation of 1.75 times from the UAV compared to field observations.

Effects of a severe storm on seagrass meadows

Extreme environmental events can strongly affect coastal marine ecosystems but are typically unpredictable. Reliable data on benthic community conditions before such events are rarely available, making it difficult to measure their effects. At the end of October 2018, a severe storm hit the Ligurian coast (NW Mediterranean) producing damages to coastal infrastructures. Thanks to recent data collected just before the event on two Posidonia oceanica seagrass meadows hit by the storm, it has been possible to assess the impact of the event on one of the most valuable habitats of the Mediterranean Sea. By means of seagrass cover and depth data gathered along four depth transects positioned within the two meadows in areas differently exposed to the storm waves, and by using models (WW3® + SWAN + XBeach 1D) to evaluate wave height and bed shear stress, we showed that meadows experienced erosion and burial phenomena according to exposure. Paradoxically, meadows in good conditions suffered more damage as compared to those already suffering from previous local anthropogenic impacts. Besides the direct effect of waves in terms of plant uprooting, a major loss of P. oceanica was due to sediment burial in the deepest parts of the meadows. Overall, the loss of living P. oceanica cover amounted to about 50%. Considering that previous research showed that the loss of the original surface of P. oceanica meadows in 160 years due to anthropogenic pressures was similarly around 50%, the present study documented that an extreme environmental event can generate in a single day a loss of natural capital equal to that produced gradually by more than a century of human impact.

Community structure and condition of seagrass meadows in Ayau Islands, Raja Ampat Regency

Seagrass meadows are an important component of coastal ecosystems, providing many ecosystem services beneficial for human well-being. Basic information about seagrass meadows in Indonesia is relatively limited, particularly in the eastern part of Indonesia, such as the remote Ayau Islands in Raja Ampat. In this paper, we reported the community structure and condition of seagrass meadows in Ayau Islands surveyed during Nusa Manggala Expedition in November 2018. We conducted the seagrass survey using quadrat transect method at five locations, i.e. Reni, Rutum, Abidon, Kanober, and Dorehkar. In the survey, we assessed parameters of community structure, including habitat extent, species composition, seagrass cover, seagrass density, macroalgae and epiphyte cover. We also recorded environmental parameters, i.e. substrate types, water clarity, salinity, water temperature, and nutrient (phosphate and nitrate). Our study showed that seagrass meadows in Ayau Islands are multispecies meadows, composed of two to five species. In overall, five species recorded in Ayau Islands are Cymodocea rotundata, Enhalus acoroides, Halodule pinifolia, Halophila ovalis, and Thalassia hemprichii. The most common species is T. hemprichii as it can be found in all locations. Meadows in Reni, Rutum, and Dorehkar are in a healthy condition, while in Abidon and Kanober are in less healthy condition. This information is of significance as baseline information needed for seagrass conservation planning.

Host and environmental determinants of microbial community structure in the marine phyllosphere.

Although seagrasses are economically and ecologically critical species, little is known about their blade surface microbial communities and how these communities relate to the plant host. To determine microbial community composition and diversity on seagrass blade surfaces and in the surrounding seawater,16S rRNA gene sequencing (iTag) was used for samples collected at five sites along a gradient of freshwater input in the northern Gulf of Mexico on three separate sampling dates. Additionally, seagrass surveys were performed and environmental parameters were measured to characterize host characteristics and the abiotic conditions at each site. Results showed that Thalassia testudinum (turtle grass) blades hosted unique microbial communities that were distinct in composition and diversity from the water column. Environmental conditions, including water depth, salinity, and temperature, influenced community structure as blade surface microbial communities varied among sites and sampling dates in correlation with changes in environmental parameters. Microbial community composition also correlated with seagrass host characteristics, including growth rates and blade nutrient composition. There is some evidence for a core community for T. testudinum as 21 microorganisms from five phyla (Cyanobacteria, Proteobacteria, Planctomycetes, Chloroflexi, and Bacteroidetes) were present in all blade surface samples. This study provides new insights and understanding of the processes that influence the structure of marine phyllosphere communities, how these microbial communities relate to their host, and their role as a part of the seagrass holobiont, which is an important contribution given the current decline of seagrass coverage worldwide.

The potential stocks and carbon uptake by seagrass meadows at Pari Island, Kepulauan Seribu, Indonesia

The development of human civilization during the last century has increased carbon dioxide content in nature that will contribute to global climate change. However, ocean water will reduce this increase by absorbing CO2. The increasing CO2 content in the ocean could decrease pH and carbonate ion, which will have negative impacts on the life of marine organisms, food production and human life. Seagrass meadows through photosynthetic processes could absorb CO2 and store carbon in large amounts for an extended period. This process could be the strategic way of resolving global climate change. The purpose of this research was to identify the species of seagrass, quantify the density and coverage of seagrass, and calculate biomass and carbon stock in seagrass meadows at Pari Island, Kepulauan Seribu. The research was carried out in February 2019. This research used quantitative field observation with the purposive sampling method. Samples were collected from 3 locations with nine stations. The obtained samples were analyzed at the Laboratory of Faculty of Fisheries and Marine Science, Diponegoro University. Carbon and sediment samples were analyzed using Loss in the Ignition (LOI) method. The results showed that there are three species of seagrass in Pari Island, i.e. Enhalus acoroides, Thalassia hemprichii, and Cymodocea rotundata. Total density value was 129.19 individual m−2 and total coverage value was 62.59%. Total stock potential of carbon value in Pari Island was 87.80 ton per ha with total area of seagrass meadows of 3.48 ha. Silty-sands mainly dominated sediment textures. It can be concluded that seagrass meadows are potential habitats to control CO2 concentration in coastal waters and to hold the rate of climate change.