Quadratic Transect Method Research Articles

Gastropods Species Associated with Seagrass Ecosystems in Pasir Putih, Manokwari

Gastropods are one of the classes of mollusks that associate well with seagrass ecosystems. The waters of Pasir Putih are included in a coastal area where many types of gastropods are found in seagrass ecosystems. However, not all types of gastropods in seagrass beds in this region are well known. For this reason, this study aims to determine the types of gastropods associated with seagrass ecosystems in the waters of Pasir Putih, Manokwari. But specifically the objectives of this study are divided into 3, knowing the types of gastropods, seagrass species and the association of gastropods with seagrass in Pasir Putih Waters, Manokwari. In sampling, the quadratic transect method was used, drawn perpendicularly from the shore towards the shore. Physical parameters of water chemistry were observed in situ, this data collection method used was descriptive method. Based on the results of the identification that has been done, that there are 115 individuals, 42 species and 15 families that exist in the White Sand Waters, Manokwari. Four seagrass species were found, namely Cymodocea rotundata, Halodule pinifolia, Halophila ovalis, and Syringodium isoetifolium.

Growth performance and biomass aquatic plants of Hydrilla verticillata in floating net cages and non-floating net cages in Laut Tawar Lake

Aquatic plants of Hydrilla verticillata have a role as a provider of natural food for the aquatic biota of Laut Tawar Lake. This study aimed to analyze the biomass growth of submerged aquatic plant of Hydrilla verticillata found in the KJA and non-KJA areas in Laut Tawar lake. The research was conducted from January to April 2022 in Laut Tawar Lake, Central Aceh Regency. The method used in determining the station of this research is purposive sampling. Data collection on aquatic plant growth was carried out at 2 observation stations using the quadratic transect method measuring 1 x 1 m. The results showed that the growth of the aquatic plant Hydrilla verticilata in Laut Tawar Lake was at a KJA station of 0.72 cm compared to a non-KJA 0.59 which was significantly different (p>0.05). The biomass of aquatic plant of Hydrilla verticilata measured was dry biomass with a value of 574 g/m2 at the KJA station while at the KJA station it was 203 g/m2. The density of water plants Hydrilla verticilata at KJA stations is 270 ind/m2 while at non-KJA stations is 173 ind/m2. It can be concluded that the growth of aquatic plants Hydrilla verticillata is greater than that of non-KJA stations.

Macrobenthos in the seagrass meadow of Taka Bonerate National Park South Sulawesi

Taka Bonerate waters are the third largest atolls in the world, rich in marine biodiversity, natural structures and aesthetics. Seagrass beds in these waters grow well on small islands, one of the coastal ecosystems that support biodiversity and have many benefits for humans in economic, social and cultural aspects. This study aimed to examine the diversity, distribution, and abundance of macrobenthos in several small islands in the Taka Bonerate National Park, South Sulawesi. The study was conducted using the quadratic transect method. A total of 24 species of macrobenthos, representing 11 species and six genera of the gastropod; 8 species and seven genera of bivalves; and 2 species and four genera of the echinoderm group were recorded. Families Conidae and Strombidae of the gastropod groups have relatively more diverse species than other families. Two species with relatively high density were represented by Protoreaster nodosus and Tripneustes sp. from the echinoderm group (class Asteroidea) with 1.15 individuals/m2 and 0.91 individuals/m2 and with a frequency of attendance of 62.50% and 75.00%, respectively. Other species of macrobenthos density, diversity, uniformity, and richness index vary between stations which relatively diverse distribution of macrobenthic fauna with a stable community. There were two clusters formed, one with more than 50% similarity and the other with low similarity. It was concluded that the relationship between macrobenthos species composition and seagrass habitat at each observation station was quite strong, where the diversity of macrobenthic species tend to increase in seagrass habitats.

The Genetic Diversity of Macroalgae on The Ekas Coast of East Lombok Based on Chromatogram Data from PCR Ampification

Macroalgae are multicellular photosynthetic organisms that live in water. Some species of macroalgae are very difficult to identify based on their morphology alone because they have great similarities. Therefore, identification of macroalgae diversity based on its genotype is very important to do in order to enrich the genetic information of macroalgae found on one of the beaches on the island of Lombok. This study aimed to analyze the genetic diversity of macroalgae from Pantai Ekas Beach, Jeowaru District, East Lombok, NTB using 18S rRNA gene markers. The research was carried out in 4 stages, namely sampling, morphological analysis of samples, isolation of total macroalgae DNA, isolation of genes by PCR amplification, agarose gel electrophoresis. Sampling was carried out at certain coordinates at east longitude and south latitude using the Ekas Beach quadratic transect method. The morphological analysis of the samples was guided by an identification key. Total DNA, macroalgae were isolated based on the spin column I DNA kit easy method. Genes were isolated by means of PCR amplification. Total DNA isolates and gene amplicons were confirmed by agarose gel electrophoresis. The results obtained were based on their morphology, all samples obtained were grouped into 9 macroalgae samples which could be divided into brown macroalgae (3 samples), green macroalgae (2 samples) and red macroalgae (4 samples). All samples have successfully isolated total DNA and its 18S rRNA gene which was confirmed by agarose gel electrophoresis chromatogram.

Density and Attendance Frequency of Seagrass In Coastal Waters of Porto Village, Saparua Island, Central Maluku

Seagrass acts as a food source in supporting the productivity of the living creatures that lives sorrounds, rearing areas, and sediment filtering systems. The Village of Porto is one of the coastal villages that has a fairly extensive seagrass ecosystem. Seagrass, locally known as "lalamong" is located quite far from residential areas, but information about the condition of the seagrass is still lacking. So, this study aims to inventory the species of seagrass found there, analyze the density and attendance frequency and assess environmental parameters for seagrass growth. The research was conducted from January to March 2019. Seagrass data was collected using the linear quadratic transect method at the five stations and each station consisted of three transects. The results showed that seagrass beds in the research area consists of eight species of seagrass, namely Enhalus acoroides, Thalassia hemprichi, Halophila ovalis, Cymodocea rotundata, Cymodocea serrulata, Halodule uninervis, Halodule pinifolia and Syringodium isoetifolium. C. serrulata is the species with the highest density number, but the highest attendance frequency is represented by E. acoroides. S. isoetifolium is the species with the lowest density and attendance frequency. Station three has the highest seagrass density but has a low on attendance frequency. Water quality parameters (temperature and salinity) are suitable for seagrass in the coastal waters of Porto village.

Mapping of seagrass ecosystem on Bontosua Island, Pangkep District, South Sulawesi, Indonesia

Abstract. Rosalina D, Jamil K, Arafat Y, Amalia R, Leilani A. 2023. Mapping of seagrass ecosystem on Bontosua Island, Pangkep District, South Sulawesi, Indonesia. Biodiversitas 24: 2023-2030. Bontosua Island is one of the islands in South Sulawesi, Indonesia, that has a seagrass ecosystem. The purpose of this study was to assess the density, cover, area, and condition of seagrass on Bontosua Island. The data collection involved the use of a quadratic transect method in the field and the Lyzenga method for remote sensing. The identification of seagrass areas was made using Landsat 8 OLI/TIRS satellite. Six seagrass species were identified, namely Cymodocea rotundata, Thalassia hemprichii, Halodule uninervis, Halodule pinifolia, Syringodium isoetifolium and Halophila sp. The results showed that C. rotundata had the highest density value of 89 Ind/m² and was categorized as rather dense, while C. rotundata also had the highest percentage cover of 58%, and Halophila sp. had the lowest percentage cover of 2%. The distribution area of seagrass beds on Bontosua Island was approximately 28.26 ha, out of a total area of 92 ha, of which approximately 6 ha was land. Observations on the condition of seagrass beds showed that 16.65 ha was healthy, 6.3 ha was unhealthy, while 5.31 ha was poor.

Macroalgae diversity in the Pari Island Cluster, Seribu Islands District, Jakarta, Indonesia

Abstract. Handayani S, Widhiono I, Widyartini DS. 2023. Macroalgae diversity in the Pari Island Cluster, Seribu Islands District, Jakarta, Indonesia. Biodiversitas 24: 1659-1667. Macroalgae are primary producers of the ocean that support the life of other organisms at higher trophic levels in aquatic ecosystems. This study aimed to determine the diversity of macroalgae in the Pari Island cluster and the diversity of water quality. The research method used is the survey method, with the quadratic transect method. Ecological index analysis using PAST 4.0 software. The relationship between diversity correlation and water quality using PCA software. The results of the study found 22 species of macroalgae consisting of 3 divisions, namely Chlorophyta (11 species), Phaeophyta (4 species), and Rhodophyta (7 species). Diversity of Pari Island (H'=2.314, E=0.594, D=0.121) and Kongsi Island (H'=1.191, E=0.481, D=0.211). The largest species are Acanthophora spicifera (M.Vahl) Børgesen (Rhodophyta), with 396 individuals; Caulerpa racemosa (Forssk.) J.Agardh (Chlorophyta), with 343 individuals; and Padina australis Hauck (Phaeophyta), with an individual number of 130. Macroalgae diversity in the Pari Island Cluster belongs to the moderate category. The diversity of macroalgae in the Pari Island Cluster is influenced by physical factors of temperature, salinity, brightness, depth, and current speed, as well as chemical factors of nitrate, orthophosphate, dissolved oxygen, heavy metal levels of Pb, Cu, and pH.

Struktur Komunitas Gastropoda pada Kawasan Mangrove Pantai Gerupuk Lombok Tengah

he purpose of this study was to determine the community structure and distribution pattern of gastropod in the mangrove area of Gerupuk Beach, Central Lombok. The field survey was conducted using the quadratic transect method and free collection in October-November 2022. The purposive random sampling was used in this study. The results showed there were 591 individuals Gastropod in all stations consisted of 4 species of Gastropod 7 families, namely Assimenia brevicula, Cassidula aurifelis, Cassidula nucleus, Littoraria carnifera, Littoraria angulifera, Littoraria scabra, Nerita undata, Cerithidea alata, Cerithidea quoyii, Telescopium Telescopium, Terebralia sulcata, Terebralia sp., Chicoreus capucinus and Nassarius reevanus. The highest abundance was found at station III with a value of 1.48 individuals per m2, where the highest abundance of gastropod species was Cerithidea alata. The diversity (H ') obtained from the three stations ranged from 1.476 to 1.996 which was categorized as medium level. Evenness index (E) from of 0.559-0.756 which were in the relatively even category. Furthermore, Domination index (C) of Gastropods range from 0.255-0.355 for low dominance. Gastropod distribution patterns in the Gerupuk Beach mangrove ecosystem are clustered and uniform. It is concluded that based on the biological indices the structure of the Gastropods community in the mangrove area of Gerupuk Beach it was in normal condition.

Mangrove ecosystem provisioning services for the sustainability and diversity of bird species in the coastal region of Lombok Island, Indonesia

Abstract. Syukur A, Zulkifli L, Mahrus H. 2021. Mangrove ecosystem provisioning services for the sustainability and diversity of bird species in the coastal region of Lombok Island, Indonesia. Biodiversitas 24: 1589-1599. Ecological services offered by mangroves are imperative for various faunal species. The present study is focused on assessing the role of mangroves in the sustainability and diversity of bird species in the coastal region of Lombok Island, Indonesia. The aims of the study are (i) to describe the conservation status of bird species and (ii) to describe the value of the ecological index of birds as an indicator of mangrove conservation. The species diversity of birds is assessed by observation, whereas the quadratic transect method is used to assess mangrove vegetation structure. Data analysis has been carried out using univariate statistical analysis, namely the Shanon-Wiener index (H'), Simpson Index (d), Evenness Index (E), Richness Index (R), and linear regression analysis. The genus Rhizophora and Avicennia species have an even distribution in the study area. Rhizophora species in the study area result from revegetation, whereas Avicennia species grow naturally. Altogether, a total of 19 bird species have been observed in the present study. Of these, eight species have a limited distribution, four bird species are Near Threatened (NT), and others are Least Concern (LC) concerning their conservation status. The estimated Diversity Index (H') is ranged between 3.09-3.67, whereas Evenness (E) and Richness (R) index are ranged between 0.72-0.85 and 7.09-10.33, respectively. The ecological index value shows that the research locations have high species diversity and richness, and species are evenly distributed across the sites. Therefore, the value of the index of bird ecology and the distribution of bird species are indicators of mangrove supply services for the preservation of birds at the study site. The study concluded that the diversity of ecological indices and the conservation status of birds are important information for the success of mangrove conservation through revegetation at the study site. However, a comprehensive study is needed on the functional relationship of mangrove supply services with the diversity of bird species to obtain validity and rehabilitation as conservation indicators.

The Structure of Mangrove Community in Regional Marine Conservation Area Gili Sulat West Nusa Tenggara

Mangrove is a type of plant that can survive on muddy substrates and at relatively high levels of water salinity. Information about the ecological value of mangrove is very important, in order to provide an overview of the current condition of mangrove. The purpose of this study is to determine the structure of mangrove community in regional marine conservation area Gili Sulat. This study used quadratic transect method measures are 10 m x 10 m (tree category), 5 m x 5 m (sapling category), 2 m x 2 m (seedling category). Based on the results this study obtained 8 true mangrove species and 2 association mangrove species in regional marine conservation area Gili Sulat. Mangrove species that have the highest frequency value is Rhizophora mucronata (0,57 ind/m²) while the lowest is Avicennia marina (0,03 ind/m²). The density for the tree level is in the rare category, while the sapling and seedling levels are in the very dense category. Bruguiera gymnorrhiza and Rhizophora mucronata species had the highest cover values in the tree and sapling category. The highest INP values in the category of tree, sapling, and seedling were 114,93% (Bruguiera gymnorrhiza), 82,32% (Rhizophora mucronata), and 69,87% (Rhizophora mucronata). Dominance index values are classified as low to moderate and the diversity index obtained is moderate.

ESTIMASI SERAPAN KARBON PADA SUBSTRAT DASAR BERDASARKAN TUTUPAN LAMUN EKOSISTEM PADANG LAMUN DI PULAU BARRANG LOMPO KOTA MAKASSAR PROVINSI SULAWESI SELATAN

The purpose of this study was to determine seagrass cover and carbon estimation in seagrass ecosystems on Barrang Lompo Island, South Sulawesi Province by using the quadratic transect method (perpendicular to the shoreline). The research was carried out in July-August 2022. Located on Barrang Lompo Island. Sample analysis was carried out at the Chemistry and Soil Fertility Lab, Hasanuddin University. The method used in this study for seagrass cover on Barrang Lompo Island was a quadratic transect (perpendicular to the shoreline) modified from the Seagrass Watch method. The consideration of choosing Seagrass Watch as a reference is that this method is suitable for monitoring activities carried out by the general public or volunteers because the implementers of seagrass monitoring in COREMAP - CTI activities are not only researchers or technicians in the seagrass field. The method used for sampling the substrate is purposive sampling method. Purposive sampling is a sampling technique with certain considerations. The results showed that the seagrass cover on Barrang Lompo Island was in the medium category with an average cover value of 37.05% and the total organic carbon content of the substrate contained in one area was 0.70 Ton/Ha with a total CO2 absorption on the substrate of the field. Seagrass in Barrang Lompo waters is 2.57 Ton/Ha.

Carbon Absorption Potential on Seagrass Types Enhalus acoroides and Thalassia hemprichii In Morotai Island Water

Seagrass is one of the most important ecosystems in coastal areas. Seagrass beds can absorb carbon of 1.15 tons/ha, with a carbon content below the substrate of 0.88 tons/ha (76.3%), higher than the carbon above the substrate, which is only 0.27 tons/ha (23, 7%). Research on carbon absorption in seagrass is still relatively carried out, so it is necessary to research the potential for carbon absorption in seagrass types Enhalus acoroides and Thalassia hemprichii in Morotai waters. The research will be carried out from September to December 2021, starting with seagrass sampling in three sub-districts (South Morotai, East Morotai, and South West Morotai Districts). The types of seagrass used were Enhalus acoroides and Thalassia hemprichii. Biomass sample analysis was carried out at the Basic Laboratory of the Faculty of Fisheries and Marine Sciences, Pacific Morotai University. Carbon analysis on seagrass was carried out at the Chemical Oceanography Laboratory of the Faculty of Marine and Fisheries Sciences, Hasanudin University Makassar. The seagrass sampling method used the quadratic transect method and sample analysis using the method Loss On Ignition (LOI). The results showed that Thalassia hemprichii has the highest carbon content in the roots, with a value of 38.94 gC/m2 to 49.48 gC/m2. In contrast, Enhalus acoroides has the highest carbon content in the roots with a carbon value of 30.77 gC/m2 to 37.86 gC/m2.

Observing Mollusca Benthic Diversity to Measure the Success of the Implementation of Mulung Culture as an Effort to Conserve Aquatics in the Waters of Lapang-Batang Island, Alor Regency, East Nusa Tenggara.

Mulung culture from an ecological perspective is to allows the environment to recover, traditionally. Mulung is a customary process, related to the closure of water areas for the extraction of aquatic resources. The impact of the implementation of the Mulung cultural tradition, the population of resources increases. This study aims to determine the benthic mollusk community in the Mulung area to measure the success rate of Mulung implementation. This information is needed as a starting point for sustainable fisheries development. This research uses the quadratic transect method and free collection. Then, the community structure was calculated using the diversity index, species evenness, species richness, and species density value, then continued by observing the quantitative similarity between locations calculated by the similarity index. The results showed that the species composition of benthic mollusks found in the Mulung area was 32 species, with a total of 261 individuals. The benthic mollusks that lived in the Mulung area had a Diversity Index (H’) value of 3.12 high category, Richness Index Value (R) of 5.75 is classified as high, the value of the evenness index of species (E) is 0.90, the evenness level of benthic mollusks is high and stable, the value of the dominance index (C) is 0.1, in the category no species dominates. The highest relative abundance of benthic Mollusca species overall with a value of 46.15% was owned by Ornopsis glanni species and the lowest relative abundance was Cypraea moneta, 6.90% value, the highest species density value with a value of 2.53 ind/m2, namely Ornopsis glanni and the lowest species density value is Diodora mississipppiensis, the value is 0.12 ind/m2. Meanwhile, the overall density of benthic Mollusca species obtained during the study was 17.40 ind/m2.

Economic value of carbon in mangrove ecosystem of Cawan Island, Indragiri Regency, Riau, Indonesia

This study aimed to calculate the economic value of carbon in the mangrove ecosystem of Cawan Island Indragiri Regency, Riau, Indonesia. Mangrove data retrieval was carried out at three stations using the 10 x 10 m quadratic transect method. A non-destructive sampling method used to estimate tree biomass, by measuring all diameters at breast height (DBH=1.3 m) of mangroves, then calculating using an allometric model. The types of mangroves found on Cawan Island are Rhizophora mucronata, Rhizophora apiculata, Xylocarpus granatum, Sonneratia alba, Sonneratia ovata, Lumnitzera racemosa, Bruguiera gymnorrhiza and Nypa fruticans. Rhizophora apiculata has the highest biomass of 2,207.48 tons.ha-1 with a carbon potential of 1,015.43 tons-C.ha-1 and carbon absorption of 3,723.24 tons-CO2.ha-1, in general, Cawan Island mangroves have a biomass value of 4,838.40 tons.ha-1 with a carbon potential of 2,199.54 tons-CO2.ha-1 and carbon absorption of 8,064.98 tons-CO2.ha-1. The total value of carbon sequestration produced by mangroves on Cawan Island is IDR.598,566,978,912.year-1.

Diversity, Ecological Index, and Distribution Pattern of Seagrass in Coastal Waters of North Bali

The coastal ecosystem that has high biological productivity is seagrass. Seagrass has ecological functions, namely as nursery, foraging, and spawning areas for organisms. Identification of seagrass species using the transect method in the waters of Penimbangan Beach, North Bali, was conducted in 2020, aiming to identify seagrass species and seagrass cover conditions in the coastal waters of Penimbangan, North Bali. The method used in this activity was the quadratic transect method, which consisted of a transect (straight line) and a quadratic frame (a rectangular frame placed on a line). The seagrass species found consisted of six species, which belonged to two families: the Hydrocharitales family with three species, namely Thalassia hemprichii, Halophila ovalis, and Halophila decipiens, and the Potamogetonaceae family with three species, namely Halodule uninervis, Cymodocea rotundata, and Syringodium isoetifolium. The density of seagrass varied but did not exceed 25 stands/m2, indicating very rare density of seagrass in these waters. Halodule uninervis species played an important role in seagrass communities in the waters of Penimbangan Beach with an Important Value Index of 89.36% at station I and 73.43% at station II. The novelty of this research is that there has not been any research on seagrass at the coast of Penimbangan, North Bali.

Keanekaragaman Flora Mangrove pada Tingkat Pohon di Cagar Alam Pulau Dua Banten

Abstract. One of the countries that has the largest mangrove forest is Indonesia, the area of mangrove forests in Indonesia reaches 3.1 million ha. Mangroves can live in tropical and subtropical climates, mangroves have so many benefits, one of which is to prevent disasters such as tsunamis and protect beaches from erosion. This research was conducted in the Pulau Dua Nature Reserve in the Banten area. This study uses a linear quadratic transect method by determining the location of the study as many as 2 station points. Data analysis was carried out quantitatively using vegetation analysis. Based on the results of the research conducted, it shows that the value of the mangrove flora diversity index is classified as low, namely H'<1. The species of mangrove flora were found such as Avicennia germinans, Avicennia marina, Avicennia officinalis, Bruguiera parviflora, and Rhizophora apiculata. The condition of the mangrove forest in the Pulau Dua Banten Nature Reserve is still relatively natural, because it is still very well preserved and the diversity of flora and fauna is still high.Keywords: mangrove, nature reserve, dua banten island

Changes in the vegetation density of Purwodadi Botanic Garden year 2015 - 2020 with Normalized Difference Vegetation Index (NDVI)

Purwodadi Botanical Gardens is one of the botanical gardens in Indonesia that used for conserve dry tropical plants and absorbs CO2 emissions. Therefore, it is important to know the changes that have occurred in the vegetation density in the Purwodadi Botanical Gardens in the last multi-temporal year (2015 – 2020). Qualitative descriptive research method is used in conducting this research. Field observations were carried out using the quadratic transect method in order to validate the data from Landsat-8 image processing and identifying the absolute density and relative density in the field. Secondary data is also used to determine changes in vegetation density using remote sensing techniques with radiometric correction processes to improve image quality due to surface reflection errors and NDVI (Normalized Difference Vegetation Index) which is used as the final analysis to obtain the results of vegetation density. The results of vegetation density increased from 2015 - 2020 due to the number of trees that grew and developed well, coupled with the regular planting of trees and other plants every year. This certainly has an impact on the air produced being cleaner and lower in temperature so that it can provide convenience for Purwodadi Botanical Garden tourists.

Life form, diversity, and spatial distribution of macroalgae in Komodo National Park waters, East Nusa Tenggara

Komodo National Park is one of the favorite destinations for both domestic and international marine tourism. Marine tourism activities have caused environmental changes and impact on fisheries and marine resources. Macroalgae were also affected by the environmental changes, so management of macroalgae was required. Ecological data of macroalgae can be used as baseline data for coastal area management. The study aimed to determine the life form, species composition, spatial distribution, and ecological aspects of macroalgae assemblages in Komodo National Park waters. The study was conducted in September 2013, in eight locations, namely Setuga, Komodo Karang Makasar, Padar Kecil, Padar, Papagarang, Mangaitan, and Muntia island. Macroalgae samples were collected by the quadratic transect method. The data analyzed were Sorensen’s similarities. A total of 42 species of macroalgae were recorded, consisting of three Phylum: Chlorophyta (19 species), Ochrophyta (8 species), and Rhodophyta (15 species). Epilithic was the dominant life form of macroalgae. In general, macroalgae can be stably attached to hard substrates. The highest macroalgae diversity was found on Mangaitan Island (22 species). Halimeda and Amphiroa were macroalgae that can be found in almost all locations. Setuga Island had similar macroalgae with both Mangaitan and Muntia islands. The differences in the number of macroalgae species were influenced by environmental pressure, topography, and substrate profile. Management of macroalgae resources was needed to maintain the sustainability of the macroalgae ecosystem.

IDENTIFIKASI JENIS MANGROVE PADA KAWASAN RESTORASI EKOSISTEM MANGROVE DI DESA KEUDE PANGA KECAMATAN PANGA KABUPATEN ACEH JAYA

This study aimed to identified mangrove species, calculated the total number and composition of mangroves, and the structure of zonation mangroves at the mangrove relocation area in Keude Panga Village, Panga District, Aceh Jaya Regency. The study was carried out on April 2021, for one month with two replications. The research method was the survey method, namely directed observation to research location. A sampling of mangroves used the quadratic transect method, which was divided into 3 transect points with the categories of tree plots measuring 10 m x 10 m, sapling plots with 5 m x 5 m, and the seedling plots measuring 1 m x 1 m. Data analyzed of the total number and composition of mangroves used Microsoft Excel 2010 and zonation of mangrove analysis was carried out descriptively. The results showed on the research at both stations founded 3 species of true mangrove and 1 species of scrub respectively, namely Rhizhopora mucronata (19% sapling level), Rhizhopora apiculata (34% sapling level), Nypa fruticans (47% tree level), Acrostichum aureum (or 100% shrub category) and Rhizhopora mucronata (23 individuals or 37% sampling level), Rhizhopora apiculata (15 individuals 20% sapling level), Nypa fruticans (36 individuals or 49% tree level), Acrostichum aureum (100% shrub category). Structure zonation of mangrove vegetation is composed of 3 species of mangroves, namely Rhizhopora mucronata which was located closest to the sea, Rhizhopora apiculata was in the middle of the mangrove ecosystem, and Nypa fruticans was a pioneer mangrove located close to the mainland.

Community structure of sea cucumber on Harapan Island and East Penjaliran Island, Kepulauan Seribu National Park, Indonesia

Sea cucumbers are marine animals of the Holothuroidea Class that have ecological, health, and socioeconomic benefits. This study aims to determine the structure of the sea cucumber community on Harapan Island and East Penjaliran Island, Kepulauan Seribu National Park, Kepulauan Seribu Regency. Data collection was conducted in January 2020, where each island was divided into two stations, and each station was divided into three substations for data retrieval. The method is a quadratic transect method using a plot measuring 1x1 m. In each square plot, observations were made regarding the type and number of sea cucumbers found and water quality parameters, including salinity, temperature, pH, DO, and total organic matter. Observation parameters include diversity index, uniformity index, frequency, density, important value index, dominance, and sea cucumber distribution index. During the study, species found on Harapan Island include H. atra, H. scabra, H. leucospilota, Bohadschia marmorata, and Stichopus herrmanni. Meanwhile, species found on East Penjaliran Island include H. atra, H. leucospilota, H. coluber, H. pardalis, H. fuscocinerea, H. hilla, Bohadschia marmorata, Stichopus ocellatus, and Stichopus monotuberculatus. The most abundant and predominant species on both islands is Holothuria atra. The average diversity index on Harapan Island falls into the low category, while East Penjaliran Island is classified as medium. The dominance index of both islands is low and has a uniform distribution. Environmental conditions and sea cucumber exploitation affect the structure of sea cucumber communities on both islands.