Halodule Uninervis Research Articles

Struktur Komunitas Ekosistem Pesisir (Lamun dan Mangrove) di Desa Sulamu Nusa Tenggara Timur

East Nusa Tenggara Province (NTT) is an archipelago province located in the south of Indonesia has a sea area of 200,000 km2 (outside ZEEI) in it has marine resources and fisheries that can be developed for the benefit of the community. Seagrass and mangrove ecosystems play an important role for the environment both physically and ecologically. To know the condition of the ecosystem, it is necessary to conduct research on the community structure of seagrass and mangrove ecosystems. This research was conducted in Sulamu Village, Kupang waters in November 2018. Each ecosystem is sampling as many as 3 stations with 3 stations each. From the results obtained, found 7 species of seagrass in salamu village waters namely Halodule pinifolia, Thalassia hemprichii, Cymodocea serrulate, Enhalus acoroides, Halophila ovalis, Cymodocea rotundata, and Halodule uninervis. Seagrass density obtained is the highest 2847 tgk/m2 and the lowest 1392 tgk/m2 with stable community conditions. In mangrove ecosystems found 11 types of mangroves found in sulamu waters namely Avicennia alba, Osbornia octodonta, Bruguiera parviflora, Aegiceras corniculatum, Rhizopora mucronata, Sonneratia alba, Rhizopora apiculata, Xylocarpus granatum, Limnitzera racemosa, Gymnanthera paludosa and Nypa frutican. The mangrove community structure in the waters of Salamu Village is unstable and dominating.

Hubungan Kondisi Rajungan (Portunus Pelagicus) dan Ekosistem Padang Lamun di Perairan Pulau Poteran Madura

C rab is one of the marine biota which has important economic value , m eanwhile, seagrass beds are one of the marine resources that have many benefits for marine life and the coastal environment. This study aims to determine the catch of small crabs and the condition of the seagrass beds in Poteran Island waters. This research uses Sentinel-2A image data downloaded from the earthexplorer.usgs.gov website; Earth Map (RBI) scale 1: 1,000,000, and field data in the form of identification of seagrass objects and water quality. The results showed that the number of female crabs that were caught was more than the male crabs. Based on the width of the carapace, the catch is categorized as unfit to catch. However, based on the weight measurement, the crabs that were caught were categorized as fit to catch. The results of the regression analysis showed that the length and weight of the crab had a fairly good relationship with a regression coefficient of 0.63. The length of the crab is more dominant than the weight. This is indicated by the negative allometric growth pattern (b<3). Many crabs are distributed in areas close to seagrass beds. Two types of seagrass were found, namely Enhalus acoroides and Halodule uninervis with rich or healthy conditions. Good water quality is believed to be one of the factors that support the growth of seagrass beds in the waters around Poteran Island.

Trace metal content in sediment cores and seagrass biomass from a tropical southwest Pacific Island

A unique feature of seagrass among other ecosystem services is to have high phytoremediation potential that is a cost-effective plant-based approach and environmentally friendly solution for metal contamination in coastal areas. The goal of this study was to assess the phytoremediation prospective of seagrass for Cu, Fe, Mn and Zn in Fiji Islands. Heavy metal content was measured in sediments and tissues of the seagrasses Halophila ovalis, Halodule pinifolia and Halodule uninervis to test for local-scale differences. The local study shows that metal concentration in sediment and seagrass tissue was significantly variable, regardless of species and sediment type. Sedimentary concentration of Cu, Fe, Mn and Zn obtained in the present study seemed to be lower than that of previous studies. The results support that H. ovalis is a good bioindicator species since it accumulated up to 5-fold more of these metals compared to the Halodule species.

Struktur Komunitas Padang Lamun Di Perairan Gili Air, Lombok Utara

Seagrass is a coastal ecosystem that has important role as a feeding ground, a spawning ground and a nursery ground for various marine biota. This study aims to examine the biodiversity of seagrass at Gili Air, North Lombok Regency, West Nusa Tenggara. This study was conducted to observe the cover percentage of seagrass, it's composition, the number of seagrass stands, canopy's height, frequency of seagrass presence, and index of importance of seagrass. Seagrass data was collected using a 50cm x 50cm quadrant transect, with a total area of 100 m2, referring to the monitoring standards set by SeagrassNet. Water quality analysis was carried out at the Bioecology Laboratory of the Aquaculture Study Program, University of Mataram, and at the Laboratory of the Marine Aquaculture Center (BPBL) of Sekotong, West Lombok. The results showed that the seagrass communities in Gili Air waters were composed of 5 (five) species: Halophila ovalis, Thalassia hemperichii, Cymodocea rotundata, Halodulea pinifolia, and Halodule uninervis, with the percentage of coverage ranging from 26.88-39.17%, and the average coverage by 31.53%. Thalassia hemperichii is the species that has the highest contribution to the seagrass community at Gili Air.

ANALISIS HUBUNGAN ATRIBUT EKOLOGI LAMUN DENGAN KUALITAS PERAIRAN DI TAMAN NASIONAL BALURAN KABUPATEN SITUBONDO

Seagrass is one of the important ecosystems in coastal but it’s prone to damage by humans or natural factors. The existence of human activities, pollution and tourism activities in the coastal of Baluran National Park are factors that allow disruption of growth and changes of seagrass ecosystem. The study was conducted in May - June 2020 in order to identify the diversity of seagrass species, density, cover and correlations of seagrass attributes with the water quality in the Baluran National Park. (diversity, equitability and dominance) and the research was conducted at 6 stations. Seagrass observations using the "Quadrat Transect" method. Environment parameters include physical and chemical parameters such temperature, salinity, pH and dissolved oxygen, nitrates, phosphates and turbidity. The relationship between water quality and the ecological attributes of seagrass was analyzed using Pearson analysis (SPSS Statistics version 23). The results obtained 10 seagrass species that are Cymodocea rotundata Cymodocea serrulata. Enhalus acoroides Halodule pinifolia Halodule uninervis Halophila minor Halophila ovalis Syringodium isoetifolium Thalassia hemprichii and Thalassodnedron ciliatum. Seagrass cover which is included in the healthy category is station 6 with a cover value of 62% and station 3 by 61%, while station 1, station 2, station 4 and station 5 are in the less rich / less healthy category, Temperature and salinity parameters have a close relation between attributes of seagrass with water qualities. Temperature has a very strong of relation in index of diversity and index of equitability with a value of 0.856 and 0.824. The correlation coefficient (r) are 0.029 for diversity and 0.044 for equitability, while salinity has a strong relationship to equitability (0.878) with a value of correlation coefficient (r) is 0.022, and the other water qualities parameters have no significant effect. against seagrass.

STRUKTUR KOMUNITAS PADANG LAMUN DI PERAIRAN PANTAI PANDAWA, BALI

This research aimed to determine the types and structure of seagrass community based on species density, species relative density, diversity index, uniformity index, and dominance index of the seagrass. This research was conducted along Pandawa Beach, Kutuh Village, South Kuta District, Badung Regency, Bali from November to December 2019. Data of seagrass were collected from 3 line transects, 3 kuadran transects from each transect, repeated 3 times. Water quality data were collected 3 times within 4 weeks. Eight species of seagrass were identified, namely: Thalassia hemprichii, Cymodocea serrulata, Halodule pinifolia, Halodule uninervis, Halophila ovalis, Halophila decipiens, Syringodium isoetifolium, and Thalassodendron ciliatum. The highest species density found at station I that was Thalassodendron ciliatum, as well as for its relative density, and the lowest was Thalassia hemprichii. At station II and III, the highest species density was found on Cymodocea serrulata and the lowest was on Halophila ovalis. The study found that the species density of seagrasses at Pandawa Beach was categorized as high density, which dominated by Thalassodendron ciliatum at station I and by Cymodocea serrulata at station II and III. Diversity index of seagrass species at station I and II was categorized as medium species diversity and low species diversity for the station III. Dominance index of seagrass species at the three station was categorized as high dominance. Similarity index of seagrass species was categorized as medium or unstable community for the station I and II, and low similarity for the station III.

Seagrass seed bank spatial structure and function following a large-scale decline

We examined the spatial structure (distribution, density) and function (viability) of the seagrass sediment seed bank, the storage of viable propagules (e.g. seeds, tubers, diaspores) in the sediment over time,in the northern Great Barrier Reef World Heritage Area in Cairns, Queensland, following a large-scale decline in seagrass area. A spatially explicit seagrass seed bank analysis was paired with a long-term annual assessment of seagrass distribution to assess seed bank spatial patterns and their relationship with the recovery and presence of seagrass, and water depth. Four years post-decline, the seed bank contained Zostera muelleri, Halodule uninervis, Halophila ovalis and Cymodocea serrulata seeds. Seed banks reflected adjacent meadow community composition; however, the density of seeds for all recorded species was significantly lower than analogous seagrass populations, indicating a reduction in the capacity for recovery from the seed bank. A spatial structure existed in both the total (viable + non-viable) and viable seed bank, and distance between seed clusters ranged from 50-550 m depending on species and seed type. Observed patterns in clustering may be explained by variation in water depth and the past distribution of seagrass in these meadows. These results demonstrate that the distribution of seagrass seeds within the seed bank, which directly influences the natural recovery of seagrass communities, is not uniform across species and may result in patchy recovery of the meadows. Therefore, the resilience provided by the seed bank in seagrass communities should not be viewed as a static level of insurance for the entire meadow, but rather as dynamic and species-specific, with variability over both space and time.

Ethnobotany of three sea grass species from Port Blair, a step towards its conservation in Andaman Islands

Ethno-phycology is the study of the relationships of human society to flora and its ecosystem. In the marine world, ethno-biology is a thriving area of research which have yielded valuable ethno-biological knowledge. The main goal of the present study was to understand the effect of abiotic factors as well as the natural and anthropogenic disturbances that shape seagrass community in Andaman Island and to reveal the knowledge of the local people, about the significance of seagrass habitat and its conservation. The qualitative study on distribution of seagrasses in Chidiyatapu (11° 29' 30" to 11° 30' 34" N and 92° 35' 10" to 92° 42' 30" E) was carried out during December2012 to February 2013. A total of three seagrass species such as Thalassia hempirichi (Ehrenberg) Ascherson, 1871, Halodule uninervis (R.Brown) J.D.Hooker 1858, Halophila ovalis (Forsskål) Ascherson 1882, where identified. Among them, T. hempirichi, and H. ovalis found in this study was reported to have the ethno-medicinal value from west coast of India. As a part of the study, the semi-structured survey was carried out among the local coastal people to analyse the Traditional Ecological Knowledge (TEK). The survey has revealed the unawareness of coastal residents about the medicinal, nutritional as well as conservational values of seagrasses. An effective implementation has to be taken to make them aware that seagrasses are fundamental components of healthy marine ecosystems and the local livelihoods that rely on them. The present findings provide the first report on the ethno-phycology of seagrasses from South Andaman Island.

Status of Seagrass community in Northern Protected Islands, Hurghada, Red Sea, Egypt

The current research aims to understanding the abundance and distribution of seagrass communities in Northern protected Islands in order to support decision-makers in the management of the natural resource, in particular the bed of seagrass in northern protected areas. During winter 2017, eight Northern protected Islands were surveyed using diving and snorkeling (Tawila Island, Ashrafi Island, Ghanim Island, Small Gubal Island, North Um ElHimat Island, South Um Elhimat Island, North Geisum Island and South Geisum Island). Three species of seagrass, Thalassodendron ciliatum, Halophila stipulacea, and Halodule uninervis, were recorded. The result revealed that, in all Islands Thalassodendron ciliatum was the highest seagrass species abundance with mean coverage of 61%. The results showed that the mean coverage of the other two species were Halophila stipulacea 43% and Halodule uninervis 42%. There is no seagrass species were recorded in two Islands, Small Gubal and south Um ElHimat. Ashrafi Island was the highest abundance of seagrass with mean coverage of 59 % and the lowest was in Ghanim Island with mean coverage of 23%. Sea cucumber in Northern protected Island was represented only by one species Holothoria area with very low abundance (8 Individuals/ 750 m2). The distribution of seagrass in northern Island was mapped using the GIS.

Effective removal of methylated phenol and chlorinated phenol from aqueous solutions using a new activated carbon derived from Halodule uninervis waste

Due to the toxicity of methylated and chlorinated phenols, it is necessary to remove them from aqueous solutions. Therefore, a highly efficient adsorbent was developed from the dead leaves of Halodule uninervis seagrass (SG) through a chemical and thermal activation process. The prepared activated carbon (SGAC) was characterized and investigated for removal of 2,4-Dimethylphenol (DMP) and 2,4-Dichlorophenol (DCP) from aqueous solutions. The batch adsorption mode was used and the effects of adsorption conditions were studied. SGAC adsorbent showed high adsorption capacities which were 364 mg DMP/g and 333 mg DCP/g. The adsorption experimental results fitted Freundlich and Langmuir models and followed pseudo-second-order kinetics. The adsorption of both adsorbates was spontaneous. The prepared adsorbent was able to remove 90% of DMP and 97% of DCP from the synthetic wastewater. This study indicated that SGAC adsorbent is efficient and reusable in the synthetic wastewater for at least four times.

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

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

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.

Pola Sebaran dan Keanekaragaman Jenis Lamun di Perairan Tanjung Pallette dan Tangkulara, Kabupaten Bone, Provinsi Sulawesi Selatan

Penelitian ini bertujuan untuk mengetahui pola sebaran dan keanekaragaman lamun di perairan Pallette dan Tangkulara. Penelitian ini dilakukan selama dua bulan, mulai Agustus hingga September 2019. Pengumpulan data dilakukan di dua titik dengan masing-masing tiga ulangan. Pengambilan data lamun menggunakan metode transek garis dan kuadran. Hasil penelitian menunjukkan bahwa terdapat 5 jenis lamun yang ditemukan di perairan Pallette dan Tangkulara, yaitu Enhalus acoroides, Thalassia hemprichii, Halodule uninervis, Cymodocea rotundata, dan Halophila sp. Keanekaragaman jenis lamun di perairan Pallette dan Tangkulara masuk dalam kategori rendah. Pola sebaran jenis lamun Thalassia hemprichii, Halodule uninervis, Cymodocea rotundata, Halophila sp. memiliki nilai pola distribusi yang mengelompok sedangkan untuk Enhalus acoroides pola distribusinya yang seragam.

What lies beneath: Predicting seagrass below-ground biomass from above-ground biomass, environmental conditions and seagrass community composition

Seagrass condition, resilience and ecosystem services are affected by the below-ground tissues (BGr) but these are rarely monitored. In this study we compiled historical data across northern Australia to investigate biomass allocation strategies in 13 tropical seagrass species. There was sufficient data to undertake statistical analysis for five species: Cymodocea serrulata, Halophila ovalis, Halodule uninervis, Thalassia hemprichii, and Zostera muelleri. The response of below-ground biomass (BGr) to above-ground biomass (AGr) and other environmental and seagrass community composition predictor variables were assessed using Generalized Linear Models. Environmental data included: region, season, sediment type, water depth, proximity to land-based sources of pollution, and a light stress index. Seagrass community data included: species diversity and dominant species class (colonising, opportunistic or persistant) based on biomass. The predictor variables explained 84–97% of variance in BGr on the log-scale depending on the species. Multi-species meadows showed a greater investment into BGr than mono-specific meadows and when dominated by opportunistic or persistent seagrass species. This greater investment into BGr is likely to enhance their resistance to disturbances if carbohydrate storage reserves also increase with biomass. Region was very important for the estimation of BGr from AGr in four species (not in C. serrulata). No temporally changing environmental features were included in the models, therefore, they cannot be used to predict local-scale responses of BGr to environmental change. We used a case study for Cairns Harbour to predict BGr by applying the models to AGr measured at 362 sites in 2017. This case study demonstrates how the model can be used to estimate BGr when only AGr is measured. However, the general approach can be applied broadly with suitable calibration data for model development providing a more complete assessment of seagrass resources and their potential to provide ecosystem services.

Do species display characteristic intraspecific levels of patchiness in a given habitat type? The case of intertidal seagrass macrobenthos

Intertidal macrobenthic assemblages associated with monospecific stands of Zostera muelleri, Cymodocea serratula, Halodule uninervis and Halophila ovalis seagrasses are known to display uniform spatial patchiness on the Moreton Bay coast of North Stradbroke Island, Queensland, as do those in Z. capensis in the Knysna estuarine bay, South Africa. Thirty-seven historical datasets of these macrobenthic assemblages were re-analysed to assess variation of local patchiness in each of the 18 most common individual assemblage components at each of these localities in terms of three metrics: overall patchiness (Lloyd's index of patchiness), levels of unoccupancy, and variation in abundance across occupied samples (Lloyd's index of mean crowding). Within-site patchiness was not caused by a restriction of individual species to specific subareas but by variation in their local density, particularly by the extent of unoccupied ‘interstitial’ spaces within patches. Especially in the more uniform Queensland conditions, the more common species occurred relatively widely across the whole locality; individual samples from which a given species was absent never themselves formed patches, the number of such samples conforming to points on truncated normal curves of the frequency of occurrence. Of the 36 species investigated, the two most abundant and widespread both in Queensland and in South Africa displayed significant or near-significant uniformity of levels of local patchiness, whilst five showed significantly uniform mean crowding and ten significantly uniform unoccupancy. This is the first demonstration that some species may display a characteristic level of patchiness in a given habitat type.

Interspecific relationship of patchiness to occupancy and abundance, as exemplified by seagrass macrobenthos

The macroecological abundance-occupancy relationship is well known; not so the potential one of patchiness with either or both. Following earlier work on the intertidal seagrass Zostera capensis in South Africa, interspecific macrofaunal patchiness-occupancy and patchiness-abundance relationships were investigated within each of a number of other seagrass systems (intertidal Cymodocea serratula, Halodule uninervis, Halophila ovalis, Zostera muelleri and Z. noltei, and subtidal Z. capensis) where faunal assemblages were markedly different in their overall abundance and species richness, and where the beds differed in their latitude, longitude, and other variables, including one in an artificial canal in a residential marina. Notwithstanding these differences, in all cases the more abundant and widespread the macrobenthic species, the less was its Lloyd's Ip patchiness, the more clearly so in respect of occupancy than of abundance. Correlation of Ip and mean crowding (Ic) values was relatively poor, and often not significant. This suggests that patchiness of a species is more influenced by unoccupancy levels than by even marked variation in abundance at occupied sites (e.g. Ic values of <0.3–>380). Indeed, values of Ip were closely correlated with the expression [a.unoccupancy + (1−a).Ic], where a is >0.80. In all cases, component macrofaunal species displayed a significant or near significant negative patchiness-occupancy relationship in the form of a power-law with a mean scaling coefficient across sites of −0.76, although data points appeared highly scattered. There was little uniformity amongst the component species in the life-style of the most patchy, most widespread or most abundant.

Current status and checklist of seagrass in Sri Lanka

This work provides the revised and updated checklist of the seagrass in Sri Lanka based on primary and secondary information. It is indeed to be an update the list of Seagrass species in Sri Lanka prepared by Abeywickrama and Arulgnanam (1991), which now been nearly three decades back. More than forty (40) published pieces of literature, herbarium sheets in the National Herbarium and author’s personal observations since 2011 were reviewed. Sri Lanka belongs to the Indo-Pacific bioregion and 15 species have been recorded so far representing seven genera. They are Enhalus acoroides, Halophila beccarii , H. decipiens , H. ovalis , H. major , H. minor , H. ovata , H. stipulacea , Thalassia hemprichii , Cymodocea rotundata , C. serrulata , Halodule uninervis , H. pinifolia , Ruppia maritima , and Syringodium isoetifolium with the estimated extend to be 37,137 ha. Halophila beccarii considered as a rare species, and has only been recorded in patchily distributed with few localities in Sri Lanka. Lack of evidences to cross check the identification of H. minor (only recorded in Negombo Lagoon) and H. ovata is a main drawback. The composition and distribution of seagrasses along the coastal zone of Sri Lanka is yet to be established. Therefore, island wide comprehensive and genetic studies could be positively contributed to fulfil the data gaps in future.

Asosiasi gastropoda di ekosistem padang lamun Perairan Senggarang Besar, Kepulauan Riau, Indonesia

This study aims to determine the type and density of gastropods, the density of seagrass, seagrass closure. It also knows the association gastropods in seagrass ecosystem in the waters of the Senggarang Besar. The research was conducted by random sampling method using a point 31 transect squares measuring 1x1 meters for observation gastropods and seagrass. Results of the study were found 12 species of gastropods. Gastropod density values range between 0.35-2.94 individual/m2. Results of research on the type of seagrass found 4 species of seagrass that is, Enhalus acoroides, Thalassia hemprichii, Halodule uninervis and Syringodium isoetifolium. A density value of seagrass species Enhalus acoides 14.32 individual/m2, Thalassia hemprichii 86.39 individual/m2, Halodule uninervis 21.58 individual/m2 and Syringodium isoetifolium 3.87 individual/m2. Total density of all seagrass 126.16 individual/m2. The closure of the Seagrass Enhalus acoides 12,63%, Thalassia hemprichii 50,96%, Halodule unnerves 13,40% and Syringodium isotifolium 0.29%. Total closure of all seagrass is 77,29%. The level of association between species of gastropods as many as 11 species have negative associations of which is Leavistrombus turturela, Strombus urceus, Planaxis sulcatus, Cerithium nesioticum, Cerithium Aluco, Cerithium zonatum, Pugilina cocholidium, Cronia margariticola, Muricodrupa fiscela, Pyrene epamella, Otopleura auriscati. While 1 species has a positive association level is kind of Rhinoclavis aspera.

Identification of dispersal barriers for a colonising seagrass using seascape genetic analysis

Seagrasses are important habitats providing many ecological services. Most species have broad distributions with maximum dispersal distances of 100's of kms, however there is limited understanding of dispersal distances of colonising species like Halodule uninervis. It commonly grows in disturbed environments and could disperse to other meadows via clonal fragments. Effective conservation management requires greater understanding of genetic structure, dispersal barriers, and connectivity timescales to predict recovery following disturbance. Despite fragment viability of up to 28 days in a congenera, this theory remains untested in situ. Using 80 neutral single nucleotide polymorphisms, we investigated genetic diversity, gene flow patterns and structure among 15 populations of H. uninervis along 2000 km of Western Australian coastline. These data were combined with a multi-generational oceanographic dispersal model and a barrier dispersal analysis to identify dispersal barriers and determine which fragment dispersal duration (FDD) and timescale over which stepping-stone connectivity occurred, best matched the observed genetic structure. The 2-7 day FDD best matched the genetic structure with 4–12 clusters, with barriers to dispersal that persisted for up to 100 years. Modelling suggested greater fragmentation of metapopulations towards the southern edge of the species distribution, but genetic diversity did not decline. Several long-term boundaries were identified even with fragment viability of up to 28 days. This suggests H. uninervis dispersal is spatially limited by factors like oceanographic features and habitat continuity which may limit dispersal of this species. This study reiterates that potential dispersal does not equal realised dispersal, and management scales of 10's of kilometers are required to maintain existing meadows. Recruitment from distances further than this scale are unlikely to aid recovery after extreme disturbance events, particularly towards the range edge of H. uninervis distribution.

ANALISIS HISTOLOGIS LAMUN Halodule uninervis dan Cymodocea serrulata YANG YANG BERASAL DARI PERAIRAN TERCEMAR LOGAM BERAT TIMBAL (Pb) DI KEPULAUAN BANGKA

Bangka Islands is a coastal area which has many coastal activities such as tin mining activities, ports/docks boatand ship transportation and residential areas. This can provide pollutant input into the water. Seagrass Halodule uninervis and seagrass Cymodocea serrulata is a flowering plant that live in the sea have extensive deployment in the waters of Bangka. One of the marine plants that can be used as a bioindicator of water pollution is seagrass. Seagrass is in the water column and the body parts interact directly with the water. This research was conducted from December 2019 to January 2020. The research sites were in the Laboratory of Muhammadiyah Gresik University and the Laboratory of Pathology, Anatomical Faculty of Medicine, University of Brawijaya Malang. The purpose of this study was to study the anatomical changes in root tissue, rhizome and leaves of Halodule uninervis seagrass andseagrass Cymodocea serrulata in response to contamination of heavy metal lead (Pb). This research was conducted in a descriptive qualitative manner with 3 body parts: roots, rhizome and leaves. The results of this study indicated that the epidermal,cells cortex and endodermalin the roots were thickened. Cell wall thickening occurs in the epidermis Rhizome. Likewise in the leaves, the phloem occurs thickening. In general, changes in the anatomical features of roots, rhizomes, and leaves were observed in response to an increase in lead concentration. The results showed that Halodule uninervis seagrass andseagrass Cymodocea serrulata developed several levels of tolerance to heavy metals, especially lead (Pb).