Enhalus Research Articles

A preliminary study of carbon dioxide and methane emissions from patchy tropical seagrass meadows in Thailand.

Seagrass meadows are a significant blue carbon sink due to their ability to store large amounts of carbon within sediment. However, the knowledge of global greenhouse gas (GHG) emissions from seagrass meadows is limited, especially from meadows in the tropical region. Therefore, in this study, CO2 and CH4 emissions and carbon metabolism were studied at a tropical seagrass meadow under various conditions. CO2 and CH4 emissions and carbon metabolism were measured using benthic chambers deployed for 18 h at Koh Mook, off the southwest coast of Thailand. The samples were collected from areas of patchy Enhalus acoroides, Thalassia hemprichii, and bare sand three times within 18 h periods of incubation: at low tide at 6 pm (t0), at low tide at 6 am (t1), and at high tide at noon (t2). Seagrass meadows at Koh Mook exhibited varying CO2 and CH4 emissions across different sampling areas. CO2 emissions were higher in patchy E. acoroides compared to patchy T. hemprichii and bare sand areas. CH4 emissions were only detected in vegetated areas (patchy E. acoroides and T. hemprichii) and were absent in bare sand. Furthermore, there were no significant differences in net community production across sampling areas, although seagrass meadows were generally considered autotrophic. Koh Mook seagrass meadows contribute only slightly to GHG emissions. The results suggested that the low GHG emissions from Koh Mook seagrass meadows do not outweigh their role as significant carbon sinks, with a value 320 t CO2 -eq. This study provided baseline information for estimating GHG emissions in seagrass meadows in Thailand.

Relationship between seagrass community structure and carbon stocks on the coasts of Karimunjawa Marine National Park, Indonesia

The seagrass ecosystem is considered one of the most effective coastal ecosystems in storing carbon. Carbon stock estimation for a certain ecosystem is highly affected by factors such as species diversity and habitat type. This study aims to investigate the relationship between plant community structure and carbon stocks in the seagrass ecosystem using a case study of six coastal sites in Karimunjawa Marine National Park, Indonesia. In this region, eight seagrass species were recorded, i.e., Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Halodule pinifolia, Halophila ovalis, Halophila minor, Syringodium isoetifolium, and Oceana serrulata. From the six study sites, the highest estimated carbon stock was 426.2 Mg C ha−1 (Site 5; Telaga, dominated by E. acoroides). Meanwhile, the lowest estimated carbon stock was 127.4 Mg C ha−1 (Site 4; Koin, dominated by T. hemprichii). The density of E. acoroides was positively correlated with the total seagrass biomass carbon stocks (r = 0.97; p < 0.01), while its dominance was positively correlated with sediment carbon stocks (r = 0.92; p < 0.05) and total seagrass ecosystem carbon stocks (r = 0.92; p < 0.05). Seagrass ecosystems with different community structures showed different carbon storage capacities. Seagrass ecosystems dominated by large-sized species such as E. acoroides showed higher estimated carbon stocks thus suggesting the importance of considering the variability of community structure in managing seagrass ecosystems for carbon sequestration and storage.

KERAGAMAN FENETIK JENIS LAMUN DI PERAIRAN PANTAI DESA POKA BERDASARKAN MORFOMETRIK SERTA IMPLIKASINYA BAGI PEMBELAJARAN BIOLOGI

Abstrak Background : This study aims to determine the phenetic diversity of seagrass species in the coastal waters of Waai Village based on morphometrics and their implications for biology learning. Methods : This research is a descriptive type of research, in which morphometric measurements are carried out to determine the phenetic diversity of seagrass species. sedan Results: The results of this study found four types of seagrass, namely Thalasssia hemprichii, Enhalus acoroides, Halophila pinifolia and Halophila ovalis. this indicates that the beach of Poka Village has a high phenetic diversity of seagrass species with varying morphometrics for each character and species, which is influenced by the type of substrate and environmental parameters. Seagrasses that have close kinship relations, namely, Thalasssia hemprichii and Enhalus acoroides are in one monophyletic group (ingroup) and have very close kinship. Likewise with and Halodule pinifolia and Halophila ovalis. The results of this study are implied in the form of teaching materials in the form of booklets that can be used by students as learning media.

PHÂN LẬP VÀ XÁC ĐỊNH CẤU TRÚC MỘT SỐ HỢP CHẤT TỪ CỎ LÁ DỪA (Enhalus acoroides) THU HÁI Ở VIỆT NAM

Three compounds were isolated from the methanol extract of the species Enhalus acoroides using a combination of several chromatographic methods. The structural elucidations of those compounds were analysed using ESI-MS and NMR. Compared with published data, the results showed that methyl pheophorbide a, adenosine, and uracil were three compounds. Keywords: Enhalus acoroides; methyl pheophorbide a; adenosine; uracil.

Influence of seasonality and edge effect on seagrass-associated macrobenthic communities: A case study from the Andaman Islands, India

Seagrass seasonality and community interactions within a meadow are local-scale ecological measures that inform management, especially in the wake of climate change. We investigated the collective influence of two ecological processes- seagrass seasonality, and edge effect, on the macrobenthic communities in the Andaman Islands, India. Thalassia hemprichii formed two mono-species intertidal meadows, while Enhalus acoroides dominated the mixed-species meadow. The study was carried out across winter (January), summer (April), and monsoon (August) in 2021 using quadrat sampling (0.5 ×0.5 m), where we surveyed the edges, center, and unvegetated micro-habitats within a meadow. Our findings suggest site-specific seasonality trends for T. hemprichii, as seasonality was governed more by the local environment than species. However, seagrass growth was the lowest in summer for both the investigated meadows. Further, we report a differential influence of seagrass seasonality on macrofaunal densities. Infaunal densities were the highest in low seagrass growth (summer), while epifaunal densities positively correlated with seagrass meadow attributes. For both investigated sites, the highest epifaunal densities were observed in winters [Site 1 = 116.8 ± 27.5 ind./m2; Site 2 = 187.8 ± 14.3 ind./m2). Lastly, we report no influence of edge effect on infauna but a little on epifauna, where for the latter, trends were site, season, and group-specific. Epifaunal holothuroids were the only group with a consistent negative edge across sites and seasons, and densities were concentrated in center > edge > unvegetated regions. In conclusion, we suggest that seagrass seasonality is a product of the local environment rather than the species type. Furthermore, seagrass seasonality substantially influenced macrofauna more than the edge effect. This study is the first attempt from the Indian waters to collectively study community responses towards seagrass seasonality and edge effect, filling a critical ecological gap in seagrass research and management in India.

Mapping and Identification of Bioactive Seagrass Compounds Enhalus acoroides in the Waters of Morotai Island

Mapping and Identification of Bioactive Seagrass Compounds Enhalus acoroides in the Waters of Morotai Island

A Comparative Analysis on Impact of Extraction Methods on Carotenoids Composition, Antioxidants, Antidiabetes, and Antiobesity Properties in Seagrass Enhalus acoroides: In Silico and In Vitro Study.

Enhalus acoroides, a tropical seagrass, is known for its significant contribution to marine ecosystems and its potential health benefits due to bioactive compounds. This study aims to compare the carotenoid levels in E. acoroides using green extraction via ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) and to evaluate the biological properties of these extracts against oxidative stress, diabetes, and obesity through in silico and in vitro analyses. E. acoroides samples were collected from Manado City, Indonesia, and subjected to UAE and MAE. The extracts were analyzed using UHPLC-ESI-MS/MS to identify carotenoids, including β-carotene, lutein, lycopene, β-cryptoxanthin, and zeaxanthin. In silico analysis was conducted to predict the compounds' bioactivity, toxicity, and drug-likeness using WAY2DRUG PASS and molecular docking with CB-Dock2. The compounds C3, C4, and C7 demonstrated notable interactions, with key metabolic proteins and microRNAs, further validating their potential therapeutic benefits. In vitro assays evaluated antioxidant activities using DPPH and FRAP assays, antidiabetic properties through α-glucosidase and α-amylase inhibition, and antiobesity effects via lipase inhibition and MTT assay with 3T3-L1 cells. Results indicated that both UAE and MAE extracts exhibited significant antioxidant, antidiabetic, and antiobesity activities. MAE extracts showed higher carotenoid content and greater biological activity compared to UAE extracts. These findings suggest that E. acoroides, mainly when extracted using MAE, has promising potential as a source of natural bioactive compounds for developing marine-based antioxidant, antidiabetic, and antiobesity agents. This study supplements existing literature by providing insights into the efficient extraction methods and the therapeutic potential of E. acoroides carotenoids.

Cytotoxicity and apoptotic effect of Methanolic extract of Red Sea seagrass, Enhalus acoroides (Linn.f.) Royle, against hepatocellular carcinoma cell line (HepG-2) and phytochemical characterization

Cytotoxicity and apoptotic effect of Methanolic extract of Red Sea seagrass, Enhalus acoroides (Linn.f.) Royle, against hepatocellular carcinoma cell line (HepG-2) and phytochemical characterization

Deciphering the Environmental Code: SEM-EDX Analysis of Lead and Mercury Distribution in Enhalus Acoroides From Kayeli Bay, Indonesia

Background: Illegal gold mining activities around Kayeli Bay have led to increased heavy metal contamination that has the potential to impair water quality and growth of Enhalus acoroides, an important seaweed species. This study aimed to investigate the distribution and concentration of heavy metals Pb and Hg in Enhalus acoroides organs (roots, rhizomes, and leaves) using SEM-EDX techniques and evaluate the impact of mining activities on the surface microstructure of these organs. Methods: Enhalus acoroides samples were collected from ten sampling points in Kayeli Bay, which were selected based on potential heavy metal contamination. SEM-EDX analysis was performed to assess the surface microstructure and distribution of heavy metals in the seaweed samples. Results: Results showed significant differences in Pb and Hg concentrations among samples from different locations, with Hg content consistently higher than Pb. Surface microstructure analysis showed morphological changes in roots, rhizomes, and leaves exposed to heavy metals, indicating environmental stress in Enhalus acoroides. Conclusion: This study confirmed the negative impact of heavy metal contamination on Enhalus acoroides in Kayeli Bay due to illegal gold mining activities. High concentrations of heavy metals, especially Hg, in seaweed organs indicate potential risks to marine ecosystem health and the sustainability of fisheries resources. These findings emphasize the need for stricter environmental monitoring and management to protect this important marine habitat from heavy metal pollution.

Ecology, distribution, and recruitment of conch (Gastropoda: Strombidae) in intertidal zones

Macroinvertebrates from Family Strombidae locally known as ‘’sikad-sikad’’ are some of the major gleaned species in the intertidal areas. This study investigated the ecology, abundance, distribution, and recruitment of conch species of Family Strombidae in the three coastal barangays (Pandaraonan, Dolores, and Tando) of Guimaras Island. The ecological aspects were assessed for three habitat types (seagrass beds, bare sand, and edges of mangrove areas) within each barangay. A total of 319 conch individuals were identified belonging to seven species (Canarium erythrinum, Canarium labiatum, Canarium mutabile, Canarium urceus, Conomurex luhuanus, Gibberelus gibbosus, and Laevistrombus canarium). The distribution of these species varied across habitats but were found most abundant in Enhalus acoroides and Thalassia hemprichii seagrass beds with patchy distribution exhibited by regular or clumping patterns. Shell lengths ranged from 15–50 mm with C. mutabile being the smallest and C. luhuanus and L. canarium as the largest species. Temporal assessment at one site (i.e., seagrass beds of Dolores) showed no significant variation in the abundance and size of adult conch species across monitoring months. However, conch juveniles assessed showed increasing trend in shell length (5, 8, and 12 mm) but with decreasing density (103, 104, and 90 individuals/m2) from February to April, and June 2023, respectively. This study provides relevant information in the development of policies to ensure sustainability of conch as a valuable fisheries commodity.

In-vitro study of cytotoxic and apoptotic potential of Thalassia hemprichii (Ehren.) Asch. And Enhalus acoroides (L.f.) Royle against human breast cancer cell line (MCF-7) with correlation to their chemical profile

BackgroundBreast cancer is the most common type of cancer diagnosed in women. Finding novel therapeutic agents with significant cytotoxic action and minimal adverse impact on normal cells becomes crucial. Today, natural anticancer agents present an unconventional method of treating cancer, either as a curative or preventative agent, with considerable concern for marine organisms.MethodsThe anticancer effect of the alcoholic extract of different Red Sea Seagrasses on MCF-7 human breast cancer cell line has been investigated. Seagrasses were collected from Wadi El Gamal, Red Sea and extracted. Qualitative HPLC analysis was performed on the extracts for the identification of their active biomarkers. This study was aimed to explore the cytotoxic impact of Thalassia hemprichii (Ehren.) and Enhalus acoroides (L.f.) Royle on MCF-7 and their mode of action. Their anti-proliferative effects on cancer cells were performed using Neutral red assay. On the other hand, their apoptotic effect and their capacity to induce cell cycle arrest were investigated by flow cytometry assay. The effect of Seagrasses on the mitochondrial membrane potential (ΔψM) was studied by using JC-1 mitochondrial membrane potential assay kit in Seagrasses treated cancer cells to Δψ Caspases 3/7activity was examined using the colorimetric method. Gene expression analysis and quantitative real time RT-PCR for the sea grasses on MCF-7 was performed. Immune-blotting technique for Bcl-2 and p53 was investigated.ResultsHPLC analysis demonstrated that the extracts contained mainly flavonoids and polyphenols such as Caffeic acid, Chlorogenic acids, catechin and kaempferol that might be responsible for these anticancer effects. Seagrasses alcoholic crude extract markedly suppressed the growth and expansion of MCF-7 cells concentration-dependently with no toxicity against normal human skin fibroblast HSF. Thalassia hemprichii and Enhalus acoroides trigger mode of cell death primarily via apoptosis as confirmed by the flow cytometry. Additionally, they have ability to induce G0/S cell cycle arrest in MCF-7. The data showed the depletion in mitochondrial membrane potential (ΔψM) in the treated cells dose-dependently Caspases 3/7activities markedly increased following 24 h treatment. Finally, Gene expression analysis showed a marked reduction in Bcl-2, Survivin and CDC2 gene expression levels and a significant increase in the expression of p53 and CC2D1A as compared to control cells.ConclusionIn summary, the Methanolic extract of seagrass, Thalassia hemperchii and Enhalus ocoroides are able to induce concentration-dependent cytotoxic effects in human MCF-7 cells through intrinsic pathway of apoptosis in MCF-7 cells. This study reveals the beneficial importance of sea grasses as a source of anticancer agents. Further in vivo study is recommended for the active isolated biomolecules.

BIOMASSA DAN SIMPANAN KARBON PADA EKOSISTEM PADANG LAMUN DI WILAYAH NUSA LEMBONGAN

The Seagrass ecosystem is one of the important ecosystems in the ocean in mitigating global warming. This research aims to examine the potential for storing carbon stocks in seagrass biomass. The purposive sampling method was used at three location points. At each location, there are 9 quadrants for a total of 27 quadrants. The types of seagrass found were Thalassia hemprichii, Cymodocea rotundata, Enhalus acoroides, Halodule uninervis, Halophila ovalis, Halodule pinifolia with moderate diversity and moderate community stability. Seagrass conditions are relatively protected between the coast and coral reefs with the highest average density of 225 ind/m2. The type of seagrass with the highest density is Thalassia hemprichii. The types of substrates are sand, coral rubble, and sandy mud. The carbon stock in the Lembongan Beach area has an area of ??89.46 hectares of seagrass beds. Around 56.32% or 3,21 tons of carbon were stored as the bottom carbon stock of the substrate and 43.67% or 2,49 tons of carbon were stored as the top carbon stock of the substrate. Keywords: Thalassia Hemprichii, Seagrass, Substate, Global Warming

Microplastic pollution on seagrass blades in two coastal bays in Northern Mindanao, Philippines

Seagrass, a key component of marine environments, can also act as a conduit for microplastics (< 5 mm) into the food web. In this pioneering study, we investigated the occurrence of microplastics on seagrass blades in the Philippines for the first time. Our research focused on Thalassia hemprichii and Cymodocea rotundata in Buru-un, Iligan City; and Enhalus acoroides and Halodule uninervis in Tubajon, Laguindingan. Using Fourier transform infrared spectroscopy (FTIR) analysis, we identified 53 particles as microplastics. Microplastic density ranged from 0.054 ±0.061 n/cm2 to 0.255 ±0.306 n/cm2, with C. rotundata exhibiting the highest density. Poly(methyl methacrylate) particles were the most prevalent in all four seagrass species. This study presents the first scientific literature on microplastics found on seagrass blades in the Philippines. It underscores the necessity for immediate and ongoing microplastic monitoring in biota and other seagrass components to trace microplastic pathways in the marine food web, highlighting the urgent need to address this issue.

Nitrogen fixation of different seasons and parts of seagrass Enhalus acoroides in Xincun Bay, northern South China Sea

In coastal ecosystems, the nitrogen fixation of seagrasses is crucial. However, the nitrogen fixation rates of seagrasses can vary spatially and temporally, especially in tropical regions. To investigate the nitrogen fixation rates of Enhalus acoroides, we used principal component analysis to examine the rates of nitrogen fixation in the roots, rhizome, and leaves of E. acoroides during the southwest monsoon (July) and the northeast season (October and January), respectively. The results showed that the nitrogen fixation rates in all three parts of E. acoroides were significantly higher during the southwest monsoon period compared to the northeast period. The rates of nitrogen fixation in the leaves of E. acoroides were found to be higher than in the roots and rhizomes. The difference in nitrogen fixation between the various parts of E. acoroides was highly significant (p<0.01). The nitrogen fixation activity of E. acoroides was significantly affected by temperature, as determined by principal component analysis. The spatial variations observed in different regions of E. acoroides were influenced by environmental factors in addition to the temperature-driven seasonal changes. The results suggest that temperature plays a vital role in the nitrogen fixation ability of E. acoroides.

Seagrass blue carbon stocks and air-sea CO2 fluxes in seagrass meadows Jepara, Indonesia

Abstract This research was conducted on August 2022 (east season) and February 2023 (west season) in Jepara waters. There are four types of seagrasses found: Ea (Enhalus acoroides), Cr (Cymodocea rotundata), Os (Oceana serrulata), and Th (Thalassia hemprichii). The analysis results suggest that the Os species has the largest organic carbon stock within seagrass (OCS-Sg), whereas Ea has the lowest. Aside from morphological measures, in this study seagrass shoot density also determined OCS-Sg for each type of seagrass. This study found that OCS-Sg is higher during the east season (26.2±2.81 gCorg m−2) than the west season (11.2±1.78 gCorg m−2). Whereas, organic carbon stock within sediment (OCS-S) is lower during the east season (41.5±0.9 gCorg m−2) and higher during the west season (56.3±0.9 gCorg m−2). During the east and west seasons, Jepara waters act as a CO2 source. However, during the east and west seasons vegetated OCS-S had higher carbon storage (41.9 and 57.2 gCorg m−2) than unvegetated (39.2 and 53.7 gCorg m−2). This is also indicated by the CO2 flux in vegetated which is lower (13.1±4.8 mmol CO2 m−2 d−1) than unvegetated (16.5±4.7 mmol CO2 m−2 d−1) during the east season. On the other hand, vegetated waters have higher CO2 flux (22.7±2.7 mmol CO2 m−2 d−1) in the west season than unvegetated (18.0±2.5 mmol CO2 m−2 d−1), this is related to seagrass shoot density during the west season which is decreasing. These findings lead to the conclusion that seagrass plays an important role for storing and absorbing carbon and storing carbon and store it in seagrass biomass and sediment even though the role of waters returns CO2 back to the atmosphere.

Seagrass decline weakens sediment organic carbon stability

Seagrass meadows are globally recognized as critical natural carbon sinks, commonly known as ‘blue carbon’. However, seagrass decline attributed to escalating human activities and climate change, significantly influences their carbon sequestration capacity. A key aspect in comprehending the impact of seagrass decline on carbon sequestration is understanding how degradation affects the stored blue carbon, primarily consisting of sediment organic carbon (SOC). While it is widely acknowledged that seagrass decline affects the input of organic carbon, little is known about its impact on SOC pool stability. To address this knowledge, we examined variations in total SOC and recalcitrant SOC (RSOC) at a depth of 15 cm in nine seagrass meadows located on the coast of Southern China. Our findings revealed that the ratio of RSOC to SOC (RSOC/SOC) ranged from 27 % to 91 % in the seagrass meadows, and the RSOC/SOC increased slightly with depth. Comparing different seagrass species, we observed that SOC and RSOC stocks were 1.94 and 3.19-fold higher under Halophila beccarii and Halophila ovalis meadows compared to Thalassia hemprichii and Enhalus acoroides meadows. Redundancy and correlation analyses indicated that SOC and RSOC content and stock, as well as the RSOC/SOC ratio, decreased with declining seagrass shoot density, biomass, and coverage. This implies that the loss of seagrass, caused by human activities and climate change, results in a reduction in carbon sequestration stability. Further, the RSOC decreased by 15 %, 29 %, and 40 % under unvegetated areas compared to adjacent Halophila spp., T. hemprichii and E. acoroides meadows, respectively. Given the anticipated acceleration of seagrass decline due to climate change and increasing coastal development, our study provides timely information for developing coastal carbon protection strategies. These strategies should focus on preserving seagrass and restoring damaged seagrass meadows, to maximize their carbon sequestration capacity.

Carbon stock, density, and biomass of seagrass in South Bangka, Indonesia

Abstract. Supratman O, Farhaby AM, Henri, Septiyati MU, Adi W. 2024. Carbon stock, density, and biomass of seagrass in South Bangka, Indonesia. Biodiversitas 25: 1736-1742. As a component of the carbon ecosystem, seagrass meadows play a crucial role in preventing climatic change. The execution of Indonesian programs pertaining to carbon economic value, carbon trading, and other endeavors aimed at attaining the Nationally Determined Contribution (NDC) requires estimated data on seagrass carbon stocks. The present study investigates the seagrass density, vegetation carbon stock, and sediment carbon stock of South Bangka, Indonesia. The investigation is carried out in the following stages: i) data collection on-site, ii) laboratory sample analysis, and iii) data analysis. The accumulation of data on-site utilizes a square transect method, which includes the gathering of sediment, sample biomass, and density information. The carbon composition of sediment and seagrass vegetation is ascertained through laboratory analysis employing the Loss of Ignition (LOI) method. The investigation uncovered eight species of seagrass in South Bangka. Cymondocea rotundata, Enhalus acoroides, Halophila ovalis, Halodule pinifolia, Halodule uninervis, Oceana serrulata, Siringodium isotifolium, and Thalassia Hemprichii are the identified species of seagrass. In South Bangka, the combined carbon stock of seagrass (above and below ground carbon) varies between 0.049±0.057 and 1.323±1.581 Mg C Ha-1. The range of sediment carbon is 110.53±42.07 Mg Corg Ha-1 extrapolated to a depth of 1 m. The results of this study suggest that the seagrass meadows in South Bangka are characterized by a significant species diversity and effectively sequester carbon in the form of biomass and sediment. This supports the National Climate Change Mitigation Program for Blue Carbon Ecosystems, an initiative that seeks to mitigate the adverse effects of climate change by utilizing the carbon sequestration capabilities of mangrove forests, seagrass meadows, and tidal marshes.

Seagrass growth at different turbidity levels

Seagrass beds are highly productive ecosystems and have ecosystem services in the coastal zone but are continuously declining globally. Mainly due to anthropogenic activities that reduce the amount of light entering the waters and reaching seagrasses, such as dredging, reclamation, sedimentation, and eutrophication. This research was conducted to determine the relationship between turbidity level and seagrass composition and morphology. The observations were conducted in November 2016 in Pangkep district on Sagara Island and Makassar City on Barrang Lompo and Lae-lae Island, South Sulawesi Province. The observation stations are determined based on the level of turbidity conditions. Sagara Island, Barrang Lompo, and Lae-lae are areas that are considered to represent turbid waters, by laying a line transect (roll meter) perpendicular to the coast and doing it 3 times. The data collected in this study related to seagrass conditions such as seagrass composition and seagrass morphometrics. Variables observed in seagrass leaf morphometric observations were leaf surface area and leaf width, leaf thickness, and distance between internodes. In addition, other data collected is environmental parameter data, such as currents, TSS, PAR, temperature, and salinity. One-way ANOVA analysis showed that there was a difference in turbidity levels between Barrang Lompo Island, Sagara Island, and Lae-lae Island with a significance value of 0.000. The types of seagrasses found on Barrang Lompo with light availability of 1735.23 µmol/m²/s are Enhalus acoroides, Cymodocea rotundata, Halodule uninervis, Halophila ovalis, Thalassia hemprichii. On P. Sagara with light availability of 170.01 µmol/m²/s, E. acoroides, T. hemprichii, Cymodocea serrulata, H. uninervis, and H. ovalis were found. Whereas in P. Lae-lae only E. acoroides was found. The results showed that the level of turbidity has an influence on seagrass morphometrics, namely leaf ratio and leaf thickness of E. acoroides species, and internode distance in H. uninervis species. Keywords:Availability of lightMorphometricsPARSeagrass bedsTurbidity

Community Structure Of Seagrass In Southeast Waters Cempedak Island West Kalimantan

Cempedak Island is one of the Coastal and Small Islands Conservation Areas (KKP3K) in West Kalimantan has various marine biological resources and important ecosystems, including seagrass. Seagrass is used as the main food source for dugong, potential habitat for various types of organisms, and potential to be developed as marine ecotourism. On the other hand, seagrass ecosystems faced threats, such as high sedimentation and the influence of anthropogenic activities. It is unknown about the current status of seagrass on Cempedak Island. This research aimed to analyze the structure of seagrass in the southeastern waters of Cempedak Island. Seagrass data collection was carried out in the tidal zone using line transect of 70 m and a quadratic transect of 1x1 m2. Data collection on seagrass and water parameters was carried out in October 2023. Determination of research sites was done using an explorative method based on the presence of seagrass. The seagrass found consisted of 4 species, namely Enhalus acoroides, Cymodocea rotundata, Halodule pinifolia, and Halophila ovalis. Seagrass cover ranged from 9.17–16.74%, with an abundance of 1.4–373.3 ind/m2. The diversity index (H') is in the low to medium category, the uniformity index (E) is in the medium category and the dominance index (C) is in the low category. Conditions of water quality parameters were into the optimal range to support seagrass life.

A pilot restoration of Enhalus acoroides by transplanting dislodged rhizome fragments and its effect on the microbial diversity of submarine sediments

Enhalus acoroides, the largest seagrass species in terms of morphology, has been observed to be declining significantly. In an effort to restore seagrass meadows, we conducted a transplantion utilizing dislodged rhizome fragments of E. acoroides as the donor materials. The growth of transplanted seagrass was monitored over a period of three years, and the impact of seagrass recolonization on sedimentary environment was assessed through analysis of sediment microbial diversity. The transplanted plants displayed notable growth, resulting in the successful recolonization of experimental plots by seagrass. The 3-year data also revealed the following findings: 1) the new shoot recruitment rate (per year) (NSR) of transplanted seagrass was 2.33 in the first year, 1.36 in the second year, and 0.83 in the third year, indicating a rapid initial growth rate of E. acoroides that subsequently slowed down; 2) the numbers of shoots and aboveground biomass of transplanted seagrass had increased by 13.0 and 15.9-fold, respectively, whereas only 3.3 and 5.3-fold increases of the natural seagrass were observed, suggesting that the transplantation of seagrass leads to a significantly accelerated recovery compared to its natural regeneration process. Furthermore, the restoration of E. acoroides resulted in a higher microbial diversity in the submarine sediments within the restoration area, as compared to the adjacent unvegetated area. This suggests that the re-vegetation of E. acoroides has a positive influence on the overall health of the sedimentary environment. This study strongly advocates for the active transplantation of dislodged E. acoroides plants resulting from human activities as a potential approach for future coastal management, specifically for the restoration of E. acoroides meadows.