Halophila Ovalis Research Articles

MORFOMETRIK LAMUN DI ZONA INTERTIDAL PERAIRAN PANTAI DESA ADMINISTRATIF MALAKU KECAMATAN SERAM UTARA KABUPATEN MALUKU TENGAH

Background: Seagrass is an angiosperm flowering plant that can grow well in coastal environments. Seagrass is a one seed plant that has roots, stems, rhizomes, leaves, flowers, fruit and seeds. Differences in substrate type, environmental conditions and nutrient content can influece the existence of seagrass species and their morphometric shapes.This research aims to determine the morphometric of seagrass in the intertidal zone of coastal waters of Malaku Administrative Village, North Seram Sub-district Methods: Sampling used a roaming survey method in the intertidal zone of coastal waters of Malaku Administrative Village. The research data were analyzed descriptively based on the results of species identification, observations and measurements of the segrass morphological structure. Results : The type of seagrass found in the intertidal zone of the coastal waters of the Malaku Administrative village is Cymodocea serulata, Cymodocea rotundata, Halophila ovalis, Halophila minor, Halodule pinifolia, Halodule uninervis, Thalassia hemprichii, and Syringodium isoetifolium. Morphometric forms of seagrass include : Root length ±3cm-16,5cm. Rhizome distance ±1cm–4,5cm. leaf blade length ± 2,4cm-15cm. The shape of the leaf blade is flat, oval, cylindrical, serrated at the tip of the leaf and small in length. Leaf width ±0,2cm-1cm, seagrass stand heigth ± 3-19,3cm. Conclusion: From the research results obtained, it can be concluded that the intertidal zone of the coastal wters of the malaku administrative village are 8 (eigth) types of seagrass and have morphometric structure that vary in size.

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.

Assessment of coral reef connectivity in improved organic carbon storage of seagrass ecosystems in Palk Bay, India

The increase in climate-related extreme events and ecosystem degradation demands consistent and sustainable climate mitigation efforts. Seagrass playing a key role in nature-based carbon sequestration mitigation strategy. Here, we investigated the role of coral reef connectivity in blue carbon dynamics with seagrass meadows with coral reef connectivity (SC areas) and without coral reef connectivity (SG areas) in Palk Bay, India. The high sediment organic carbon was recorded in SC areas (90.26 ± 25.68 Mg org.C/ha) and lower in SG areas (66.96 ± 12.6 Mg org.C/ha). The maximum above-ground biomass (AGB) was recorded in Syringodium isoetifolium (35.43 ± 8.50) in SC areas and the minimum in Halophila ovalis (7.59 ± 0.90) in SG areas, with a similar trend observed in below-ground biomass (BGB). Our findings highlight the importance of coral reefs in enhancing the blue carbon potential of seagrass ecosystems and underscore the need for integrated conservation and restoration strategies for coral reefs and seagrasses.

Methods Using Marine Aquatic Photoautotrophs along the Qatari Coastline to Remediate Oil and Gas Industrial Water.

Qatar and other Gulf States have a diverse range of marine vegetation that is adapted to the stressful environmental conditions of seawater. The industrial wastewater produced by oil and gas activities adds further detrimental conditions for marine aquatic photosynthetic organisms on the Qatari coastlines. Thus, these organisms experience severe stress from both seawater and industrial wastewater. This review discusses the biodiversity in seawater around Qatar, as well as remediation methods and metabolic pathways to reduce the negative impacts of heavy metals and petroleum hydrocarbons produced during these activities. The role of microorganisms that are adjacent to or associated with these aquatic marine organisms is discussed. Exudates that are released by plant roots enhance the role of microorganisms to degrade organic pollutants and immobilize heavy metals. Seaweeds may have other roles such as biosorption and nutrient uptake of extra essential elements to avoid or reduce eutrophication in marine environments. Special attention is paid to mangrove forests and their roles in remediating shores polluted by industrial wastewater. Seagrasses (Halodule uninervis, Halophila ovalis, and Thalassia hemprichii) can be used as promising candidates for phytoremediation or bioindicators for pollution status. Some genera among seaweeds that have proven efficient in accumulating the most common heavy metals found in gas activities and biodegradation of petroleum hydrocarbons are discussed.

Halophilomyces hongkongensis, a Novel Species and Genus in the Lulworthiaceae with Antibacterial Potential, Colonizing the Roots and Rhizomes of the Seagrass Halophila ovalis.

Seagrass serves as a quintessential reservoir for obligate marine Lulworthiaceae fungi. Our current knowledge of the mycological diversity associated with seagrass in Hong Kong remains poor. We analyzed the diversity of fungi associated with the most widely distributed seagrass species in Hong Kong Halophila ovalis (Hydrocharitaceae), using a combination of culture-based methods and high-throughput amplicon sequencing. Halophilomyces hongkongensis, a novel fungal species in a newly proposed genus within the Lulworthiaceae family, was isolated from H. ovalis roots and rhizomes. The novel fungus showed distinct morphological characteristics, while both combined 18S-28S and internal transcribed spacer (ITS) phylogenetic trees based on maximum likelihood and Bayesian methods supported its discrimination from other existing Lulworthiaceae members. The ITS2 region in the Illumina sequencing results of multiple H. ovalis compartments, water, and adjacent non-seagrass sediments revealed continuous recruitment of H. hongkongensis by H. ovalis throughout the year despite dramatically fluctuating environmental conditions, with remarkably high proportions of this taxon found in root and rhizome internal tissues, possibly indicating a strong and specialized relationship established between the Lulworthiaceae fungal partner and its seagrass host. The inhibitory abilities exhibited by H. hongkongensis against Staphylococcus aureus SA29213 and ATCC 43300 (methicillin-resistant) may imply its capacity in producing (novel) antibacterial compounds. The discovery of H. hongkongensis as the first novel Lulworthiaceae taxon in Hong Kong, along with its distributional pattern in the seagrass meadow, provides valuable insights into the systematics and ecology of this strictly marine fungal family.

Baseline study on the seagrass distribution and species diversity of the seagrass at West Sea (Viet Nam) with integrated approaches

Seagrass beds are one of the most important marine ecosystems, but they are facing critical threats worldwide. Like other regions in the world, this fragile ecosystem is declining in Viet Nam. The seagrass distribution and species diversity of some archipelagos and islands of the West Sea of Viet Nam are still poorly studied. In this study, small scale seagrass beds from 30 sites were mapped, species diversity was also determined. Ground surveys and SENTINEL-2 image analyses were applied to determine the distribution of seagrass meadows in the region. Morphological examination was used to identify specimens. For the Halophila ovalis complex, a nuclear genetic marker (ITS1–5.8S-ITS2) was applied. In addition, the consensus ITS2 secondary structure was also used to check the genetic relationship among H. ovalis and closely related species including H. minor, H. major and H. nipponica. The results indicate that the total area of seagrass in the West Sea of Viet Nam is updated with 7632 ha.

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

Comparative effects of heat stress on photosynthesis and oxidative stress in Halophila ovalis and Thalassia hemprichii under different light conditions

This study investigated the physiological responses of two tropical seagrass species, Halophila ovalis and Thalassia hemprichii, to heat stress under varying light conditions in a controlled 5-day experiment. The experimental design included four treatments: control, saturating light, heat stress under sub-saturating light, and heat stress under saturating light (combined stress). We assessed various parameters, including chlorophyll fluorescence, levels of reactive oxygen species (ROS), antioxidant enzyme activities, and growth rates. In H. ovalis, heat stress resulted in a significant reduction in the maximum quantum yield of photosystem II (Fv/Fm) regardless of the light condition. However, the effects of heat stress on the effective quantum yield of photosystem II (ɸPSII) were more pronounced under saturating light conditions. In T. hemprichii, saturating irradiance exacerbated the heat stress effects on Fv/Fm and ɸPSII, although the overall photoinhibition was less severe than in H. ovalis. Heat stress led to ROS accumulation in H. ovalis and reduced the activity of superoxide dismutase (SOD) and ascorbate peroxidase in the sub-saturating light condition. Conversely, T. hemprichii exhibited elevated SOD activity under saturating light. Heat stress suppressed the growth of both seagrass species, regardless of the light environment. The Biomarker Response Index indicated that H. ovalis displayed severe effects in the heat stress treatment under both light conditions, while T. hemprichii exhibited moderate effects in sub-saturating light and major effects in saturating light conditions. However, the Effect Addition Index revealed an antagonistic interaction between heat stress and high light in both seagrass species. This study underscores the intricate responses of seagrasses, emphasizing the importance of considering both local and global stressors when assessing their vulnerability.

Predicting seagrass ecosystem resilience to marine heatwave events of variable duration, frequency and re‐occurrence patterns with gaps

AbstractBackgroundSeagrass, a vital primary producer habitat, is crucial for maintaining high biodiversity and offers numerous ecosystem services globally. The increasing severity and frequency of marine heatwaves, exacerbated by climate change, pose significant risks to seagrass meadows.AimsThis study acknowledges the uncertainty and variability of marine heatwave scenarios and aims to aid managers and policymakers in understanding simulated responses of seagrass to different durations, frequencies and recurrence gaps of marine heatwaves.Materials and MethodsUsing expert knowledge and observed data, we refined a global Dynamic Bayesian Network (DBN) model for a specific case study on Halophila ovalis in Leschenault Estuary, Australia. The model evaluates the potential impact of marine heatwaves on seagrass resilience, examining stress resistance, recovery and extinction risk.ResultsSimulations of different marine heatwave scenarios reveal significant impacts on seagrass ecosystems. Scenarios ranged from 30‐ to 90‐day heatwaves, with longer durations causing more significant biomass decline, reduced resistance, higher extinction risk and prolonged recovery. For instance, recovery time may increase from 18 to 26 months with four 60‐day and from 24 to 47 months with four 90‐day marine heatwave events. Increasing the frequency of marine heatwaves from one to four annual events, with no gaps between occurrences, could raise extinction risk from 11% to 55% for 60‐day events and from 17% to 83% for 90‐day events. However, introducing gaps between heatwaves enhanced resilience, with spaced events showing lower extinction risks and quicker recovery than consecutive yearly events.DiscussionThe study demonstrates the DBN model's utility in simulating the impact of marine heatwaves on seagrass, providing tools for risk‐informed assessment of management and restoration efforts. While these simulations align with existing research on temperature impacts on seagrass, they are not empirical.ConclusionFurther research is necessary to expand our understanding of climate change effects on seagrass ecosystems, guide policy and develop strategies to strengthen marine ecosystem resilience.

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.

Seagrass Community Structure and Ecosystem Carbon Stocks Along the Shoreline of Semujur Island, Bangka Belitung Province, Indonesia

Seagrass meadows serve as vital blue carbon ecosystems, sequestering significant amounts of CO2 and playing a crucial role in climate change mitigation. Semujur Island, located in the Bangka Belitung Province, exemplifies numerous small Indonesian islands boasting extensive seagrass meadows lining their shores. This research seeks to (1) describe the community structure of seagrass on Semujur Island, (2) assess the carbon storage within the seagrass ecosystem, and (3) analyze the relationship between seagrass community structure and carbon reserves across three distinct sites. According to the results of this study, there are eight species of seagrass on Semujur Island, i.e., Cymodocea rotundata, Enhalus acoroides, Halodule uninervis, Halophila ovalis, Oceana serrulata, Syringodium isoetifolium, Thalassia hemprichii, and Thalassodendron ciliatum. Diversity indices varied among sites, ranging from 1.48 to 1.72. Species evenness indices varied between 0.83 and 0.92, while dominance indices varied between 0.20 and 0.28. The highest estimated carbon stock was obtained at the site dominated by the species H. uninervis (75.11 MgC/ha); followed by the site dominated by T. hemprichii (50.55 MgC/ha). The correlation between seagrass community structure, including density and coverage, and carbon stocks demonstrated a moderate positive correlation, with coefficients of 0.430 and 0.528, respectively (p&lt;0.05). This research highlights the significance of integrating ecological dynamics into the management of seagrass ecosystems to enhance climate change mitigation efforts. Additionally, it offers valuable data as a reference for the restoration and conservation of seagrass ecosystems.

Potential Carbon Stock of Seagrass Biomass in Malang Regency

Research on blue carbon content in seagrass beds also has important implications for coastal ecosystem management. The goals of this research are: (1) To determine the composition of seagrass species; (2) to analyze the health of the seagrass ecosystem; and (3) and to analyze the carbon content stored in seagrass biomass on the coast of Malang Regency. This research was conducted in 2018 at five stations, namely: Kondang Merak Beach (St 1), Balekambang Beach (St 2), Gatra Beach (St 3), Sendangbiru Beach (St 4), and Waru-Waru Beach (St 5) of Malang Regency. The method used to collect data refers to Seagrass Watch. The biomass value of seagrass species can be estimated by measuring the wet weight and dry weight of seagrass. Analysis of carbon content in seagrass biomass can be calculated using a method that refers to The First Nation-Wide Assessment Identifies Valuable Blue-carbon. There are five types of seagrasses found on five beaches in Malang Regency, namely: Halodule pinifolia, Halodule uninervis, Halophila ovalis, Syringodium isotifolium, and Thalassia hemprichii. This seagrass meadow ecosystem is in an unhealthy condition, with a small biomass value. Seagrass beds that are formed only in the form of small spots (1.19 Ha) are known to be able to store carbon of 0.0544 Mg C.

The potential of seagrass ecosystems in Waai and Liang coastal waters on Ambon Island as carbon storage sites

Seagrass ecosystem is one of the coastal ecosystems that can absorb carbon and subsequently store it at a high capacity. This research aimed to study carbon stocks in biomass based on seagrass type and density, differences in carbon stocks between below-ground and above-ground, and the potential for carbon storage of the seagrass ecosystem on the coast of Waai and Liang, Ambon Island. Five seagrass species species were found, including Enhalus acoroides, Halophila ovalis, Halodule pinifolia, Thalassia hemprichii and Cymodocea rotundata,. Based on the results, halassia hemprichii was predominant in Liang waters and Halodule pinifolia was predominant in Waai waters. The highest seagrass biomass in both the below ground and above ground was found for Cymodocea rotundata in Waai waters and Thalassia hemprichii in Liang waters. The total carbon stock in Liang waters was 39.75 gC/m2, whereas that in Waai waters was 56.46 gC/m2. The results showed that the total carbon stock below ground was much greater than above ground, suggesting that more carbon is stored below seagrass substrate than above it in both Waai and Liang coastal waters.

Evaluating the seagrass ecological condition and habitat extent in Karimunjawa National Park, Jepara Indonesia

In the coastal ecosystem, seagrass meadows play a vital role in delivering ecosystem services such as provision, control, and support. However, this ecosystem is one of the most threatened in the coastal environment, and it has been degraded as a result of anthropogenic disturbance and rapid environmental changes. Furthermore, the extent of the seagrass meadows is unknown, and the health of the meadows is unmonitored and unrecorded. There is little information on the current state of the seagrass extent and health conditions in Karimunjawa National Park. We evaluate the abundance, states, and health conditions of the seagrass meadows based on the ecological quality index in Karimunjawa National Park, Jepara, Indonesia. This district has a vast extent of seagrass meadows but has been affected by the expansion of the industrial/tourism area within the region. This study aimed to assess the seagrass current condition based on the ecological quality index. The result showed that the total seagrass extent area in Karimunjawa National Park was 969,15 ha where seven species were found in this area, including Enhalus acoroides, Thalassia hemprichii, Cymodocea rotundata, Cymodocea serrulate, Halodule pinifolia, Halophila ovalis and Halodule uninervis. Seagrass meadow coverages were moderate and categorized as less healthy. The seagrass ecological quality index value was 0.66 which indicated that the seagrass condition in Karimunjawa National Park was moderate. Ecological factors that affect the seagrass state are epiphyte cover and macroalgal cover.

Seagrass Meadow Conditions in Coastal Waters of Siwak Bay Central Lombok

Seagrass is a flowering plant thriving in shallow sea waters and estuaries. Seagrass ecosystems are essential in supporting life in shallow seas as primary producers, biota habitats, sediment trappers, and nutrient trappers. Environmental factors affecting seagrass growth include temperature, salinity, pH, and substrate. The study was conducted in March-June 2023. This study aimed to determine the type and condition of seagrass beds in the waters of Siwak Bay. The method used in this study is the quadrant transect method at three research stations. There are seven types of seagrass identified, namely Thalassia hemprichii, Halophila ovalis, Cymodocea rotundata, Cymodocea serrulata, Halodule pinifolia, Halodule uninervis, and Syringodium isoetifolium. The percentage of total seagrass cover is at a value of 37%-61%, indicating that the condition of seagrass beds in the waters of Siwak Bay is included in the unhealthy category. The highest species density found at station III in Halodule pinifolia was 483.5 stands/m², and the lowest was found at stations II and III in Thalassia hemprichii and Cymodocea serrulata with 0 stands/m². The average density value of seagrass beds in the waters of Siwak Bay is very dense. The highest type frequency was found in Cymodocea rotundata, with a value of 2.53. The tallest species diversity and diversity index was found at station II with values of 1.56 and 0.8, respectively. In contrast, the highest dominance index was found at station I, with a value of 0.44.

The viability of seagrass ecosystems for supporting dugong recovery in Kenya

Seagrasses are the primary source of food for dugongs and a good indicator of marine ecosys- tem health. The East African dugong (Dugong dugon) population is listed as critically endan- gered under the IUCN Red List. This study aimed to document the status of seagrass beds and evaluate their potential for supporting dugong recovery in Kenya. A cross-sectional survey was conducted in December 2016 to March 2017, with data gathered through desktop reviews, inter- views, beach surveys and aerial surveys. Seven seagrass species were found at sampled sites, namely Syringodium isoetifolium, Thalassodendron ciliatum, Halophila ovalis, Zostera capensis, Thal- assia hemprichii, Cymodocea serrulata, and Halodule uninervis. Halodule and Halophila seagrass spe- cies are important in the diet of dugongs. Two dugongs were sighted during the aerial survey. The spread of sea urchins, unplanned infrastructure development, Illegal, Unreported and Unregulated fishing, and boat anchors negatively affected seagrass ecosystems and hence dugong distribution in Kenya.