Line Transect Research Articles

Habitat suitability modelling of Koklass pheasant (Pucrasia macrolopha) in moist temperate forest.

The decreasing status of on IUCN of Koklass pheasant (Pucrasia macrolopha) belongs to the family Phasianidae and the order Galliform needs the attention of researchers. The species with habitats as low as 6,000 feet and as high as 11,000 feet certainly cover a broad variety of habitats, such a wide altitude range embraces a diverse range of habitats. Insufficient research has been conducted on the suitability of moist temperate forests as a potential habitat for the Koklass pheasant. Therefore, this study was carried out to explore habitat suitability in 15 different sites which were located in the 4 districts of Hazara Division using GIS data science and environmental variables. A random sampling technique was used for laying out the transect. Overall, 45 line transects (Length 2-4 km, Width 10-30 m) were laid out in study sites. The size of sample plots for trees was 10x10m, for shrubs (4 x4m), and herbs and grasses 1x1m. The other habitat parameters like elevation, slope, cover, and frequency of plant at each point were also considered. We found the uneven distribution of Koklass pheasant in the Hazara Division. There were 59 occurrence points identified and highlighted the distribution of Koklass pheasant in the study area. Although all environmental variables were preferred by Koklass pheasant in its habitat statistical analysis proved that slope, level of disturbance, tree and shrub frequency of habitat contributed mostly to the presence of Koklass in each study site except the contribution of soil and herbs. The potential suitable habitat of Koklass pheasant was estimated to be 439.6 km2 areas starting from Abbottabad to Mansehra in the Hazara division. Awareness and enforcing legal protection are recommended for the conservation of Koklass Pheasant in Moist temperate forest.

Habitat Preference of Lesser Whistling Ducks (Dendrocygna javanica) in Selected Wetlands within Colombo Ramsar Wetland City

Lesser Whistling Ducks (LWD) (Dendrocygna javanica) mostly occur in flocks and inhabit lakes, ponds and marshes within freshwater wetlands. They feed mainly on plants taken from water (seed, shoots, tuber and leaves), vertebrates (fishes) and invertebrates (mollusks and worms). In this study, habitat preference of LWD in five selected wetlands in Colombo Ramsar Wetland City (CRWC); Beddagana Wetland Park (BWP), Diyasaru Park (DP), Heen Ela Marsh (HEM), Thalangama Marsh (TM) and Kimbulawala Wetland (KW) was studied from May 2021 to April 2022 as wetlands in urban areas act as the last resort for many resident and migratory bird species and play a major role in the assemblage and conservation of water birds. Habitats present in the selected wetlands were categorized as open water body, floating vegetation, trees, grassland, paddy field, shrubs, bare land. Percentage cover of each habitat type at each sampling site were estimated using quadrat method. LWD were surveyed using line transects of 100m in length, laid in each selected study site to cover representative habitats and observations were made up to 30m towards either side of each transect. Sampling was done in three time slots of the day, morning, mid-day and evening. Floating vegetation, open water body and grassland were the preferred habitat types of D. javanica in BWP, DP, HEM and TM. LWD were not recorded in KW. Floating vegetation (54.97%) was the most preferred habitat by LWD in each study site followed by open water body (24.70%) and grassland (15.82%) habitat types. Eicchornia crassipes (Common water hyacinth) and Salvinia molesta (Giant salvinia) were their most preferred floating vegetation type. Higher abundance of LWD was recorded in TM (83.22%) followed by DP (9.17%), BWP (4.16%) and HEM (3.45%). TM which had higher abundance of LWD had higher floating vegetation coverage (28%) and was rich with E. crassipes and S. molesta. Present study revealed that, LWD mostly used E. crassipes and S. molesta as their main foraging and resting sites. Management of invasive alien species have been undertaken in Colombo wetlands and as E. crassipes and S. molesta are alien species they are currently being removed. Therefore, outright removal of E. crassipes and S. molesta may not be suitable and a monitored removal program that will conserve this habitat type should be implemented in order to conserve the habitats preferred by LWD in CRWC. 
 Keywords: Lesser whistling ducks, Wetlands, Habitat preference

Spatial variability of organic matter in two mangrove ecosystems in Langkawi, Kedah, Malaysia

Abstract. Ramli R, Pardi F, Singh HR, Roslani MA, Aziz KNA, Kamaruddin SA. 2024. Spatial variability of organic matter in two mangrove ecosystems in Langkawi, Kedah, Malaysia. Biodiversitas 25: 329-336. Organic matter is a crucial factor influencing mangroves' structure and species composition. The present study aimed to assess and compare the organic matter content in the sediment of Pulau Dayang Bunting and Sungai Kilim mangroves ecosystem in Langkawi, Kedah. The spatial variation of the organic matter contents was measured from the sediment at different zones in a line transect at each location. The mean of organic matter content recorded in the Pulau Dayang Bunting mangroves community was recorded from 13.67% to 15.74% and 13.06% to 16.57% in the Sungai Kilim mangrove community which were classified in the medium category. Results of Two-way ANOVA analysis revealed significant differences in the organic matter content between mangroves communities and only organic matter content in Station 2 was significantly different at the lower, middle, and upper zones (ANOVA one way, P<0.05). Only salinity has a negative correlation with the organic matter content in the study area (r (34) = [-0.41], p = [0.014]). The upper zones exhibited a greater concentration of organic matter due to enhanced accumulation facilitated by the vertical water mixing. Mangroves age, vegetation density, salinity, and sediment types are also crucial factors in maintaining organic matter content in the mangrove ecosystem.

Unveiling coastal diversity: An inventory and conservation report of beach forest flora of Surigao del Sur, Philippines

Abstract. Ramos GB, Panduyos JB, Caray RE, Bacquial LS. 2024. Unveiling coastal diversity: An inventory and conservation report of beach forest flora of Surigao del Sur, Philippines. Biodiversitas 25: 421-430. Coastal greenbelts, comprise mangroves and beach forest trees, are pivotal in disaster mitigation and climate change resilience. Despite the evident importance of these coastal ecosystems, they are often overlooked in research due to a lack of comprehensive data on species community structure and their broader ecological importance. Hence, this present study was conducted to document beach forests composition and conservation status in selected coastal municipalities of Surigao del Sur, Philippines. The study was conducted in five sampling locations, namely, La Paz, Bil-at, Balibadon, Poblacion Cagwait and Arangasa Island. At each sampling location, a 2 km transect line, parallel to the beach’s shoreline, was established having a 100 square meter sampling plots spaced 50m apart. Beach species frequency counts, percentages, and diversity indices were quantified. The study documented 27 beach forest species belonging to 21 families and 25 genera with the dominant species being Crinum asiaticum, Cocos nucifera, Millettia pinnata, Timonius compressicaulis, and Terminalia catappa. Both Arangasa Island and La Paz beach forests have the highest species diversity (H’ = 2.04); however, Cagwait has the highest species richness (Margalef = 2.34). This study has potential to significantly contribute in addressing existing data gap regarding beach forest species in the Philippines. With the looming threat of extinction due to infrastructural development and anthropogenic activities, the study's outcomes stand as an urgent call to action; thus, a collaborative endeavor of Local Government Units, academicians, and community for conservation and protection before these species succumb to the threat of extinction.

Community structure of sea cucumber (Echinodermata: Holothuroidea) resources in the Kepulauan Seribu National Park, Indonesia

Abstract. Helmiyani NA, Suryanti S, Purwanti F. 2024. Community structure of sea cucumber (Echinodermata: Holothuroidea) resources in the Kepulauan Seribu National Park, Indonesia. Biodiversitas 25: 344-354. Kepulauan Seribu National Park has several types of commercial sea cucumbers (Echinodermata: Holothuroidea). Many local and foreign communities take sea cucumbers from nature without paying attention to habitat conditions. This phenomenon causes a decrease in the availability of sea cucumbers. This research was carried out to help stabilize the sea cucumber ecosystem and its availability to be considered for its sustainability. This research was conducted in May-June 2023, at Kelapa Dua Island and Panjang Kecil Island in the Kepulauan Seribu National Park, Jakarta, Indonesia. Sampling was carried out using the field observation method, where the location points were determined by adjusting where the sea cucumber habitat was located. Sampling points were carried out on two islands, each island was assigned 4 station points, with the total number of stations on both islands being 8 station points. Sampling was carried out using perpendicular transect lines, divided into 3 zones. The data analyzed includes the Index of Diversity, Evenness, Dominance and Density. Based on the results 12 species were obtained from both islands, with the genera Holothuria, Stichopus, Bohadschia, Actinopyga, and Synapta. The highest density is at station 3 Kelapa Dua Island, with a density value of 0.57 (ind/m2), and the lowest density is at station 1 Panjang Kecil Island with a value of 0.14 (ind/m2). The results show a moderate diversity value, a low Dominance value, and a small evenness value, while the water quality result value can be said to be good because it has a value according to the survival quality standards for sea cucumbers in marine waters.

KEANEKARAGAMAN JENIS ANGGREK DI JALUR PENDAKIAN WIRAYANA GUNUNG CAKRABUANA KABUPATEN MAJALENGKA

The existence of orchids in nature continues to decline due to habitat destruction and overexploitation. Conservation efforts that have been carried out so far have often experienced difficulties due to insufficient data and information as a basis for management, including conservation areas. The more widespread forest destruction will result in these species being threatened with extinction. This study aims to determine the diversity of orchid species, on the Wirayana Mount Cakrabuana Climbing Path. The information is expected to provide an initial contribution to the area management and orchid conservation efforts on the Wirayana Mount Cakrabuana Climbing Path. This research was conducted by means of a vegetation survey, sampling and documentation by exploring the existence of orchids. The sampling technique used the path transect method. The number of transects used is one line transect with a line length of 1500 m with a total of 22 sample plots. Data analysis was carried out by calculating the Important Value Index (INP), Species Dominance Index (Di) and Species Diversity Index (H'). The results showed that in the natural forest area of ​​Mount Cakrabuana there were 22 species of individuals which included 7 species of terrestrial orchids and 15 species of epiphytic orchids with a total of 243 individuals found. From the results of the calculation of species diversity, it is stated that the diversity of orchid species in the natural forest area of ​​Mount Cakrabuana is classified as moderate (2,973). This information is very important, especially for area managers in preserving the biodiversity of Mount Cakrabuana, especially orchids in the future.

Effects of Land Cover on the Taxonomic and Functional Diversity of the Bird Communities on an Urban Subtropical Mountain

Mountain ecosystems are crucial for global biodiversity conservation. However, their landscape features are constantly changing owing to urban expansion. Understanding the relationships between biotic communities and landscape features is essential for biodiversity conservation. This study aimed to examine the effect of land cover type on avian communities in Lishui, a mountainous urban area in eastern China. Avian surveys were conducted using 168 line transects in total across different land cover types once per season from December 2019 to January 2021. We assessed the diversity of bird communities by calculating various metrics at both taxonomic and functional levels. Among the land cover types measured, woodland, built-up land, cultivated land, and water bodies significantly influenced bird community diversity and composition. Species richness, species abundance, and functional richness were negatively correlated with the proportion of woodland but were positively correlated with the proportion of non-natural land cover, such as built-up and cultivated land. In contrast, functional evenness was positively correlated with the proportion of woodland and grassland but negatively correlated with the proportion of non-natural land cover. Land cover type also exhibited significant correlations with avian functional characteristics such as diet, foraging strata, and body mass, thereby influencing the overall community structure. Our results indicated that mountainous landscape patterns substantially affect avian communities. Different land cover types possess varying resource endowments that affect the distribution of avian species. Therefore, urban landscape planning in mountainous areas should carefully consider the various functions provided to organisms by different types of land cover to promote biodiversity.

Population study of long-tailed macaque (Macaca fascicularis) on Deli Island, Banten, Indonesia

Abstract. Fitriana YS, Sulistyadi E, Tohir RK, Hasibuan MM, Rifaie F, Maryanto I, Lubis AM, Rifqi MF. 2024. Population study of long-tailed macaque (Macaca fascicularis) on Deli Island, Banten, Indonesia. Biodiversitas 25: 144-150. Understanding the distribution and population dynamics of primate species is essential for practical conservation efforts. However, such information is often unavailable, even for species whose populations appear abundant. The long-tailed macaque (Macaca fascicularis Raffles, 1821) is a species with a wide range in Southeast Asia, including Sumatra, Java, Kalimantan, Bali, Lombok, and Lesser Sunda in Indonesia. However, comprehensive data on population density across its Indonesian distribution area still needs to be improved. To address this knowledge gap, we conducted a thorough survey and study to estimate the population density of long-tailed macaques on Deli Island, located in Banten Province. Long-tailed macaques were introduced to Deli Island between 1989 and 1990 with a total of 1000 males and 10,000 females. To date, a total of 9,500 individuals have been harvested from this island in the period 1991-2010. We employed the line transect distance sampling (LTDS) method with a perpendicular distance approach that covered all habitat types throughout the island. Our findings revealed that the population density of long-tailed macaques on Deli Island is approximately five individuals per hectare, with an estimated total population of 4,860. The data pertaining to age structure and sex ratio is notably limited, primarily due to challenges in identification caused by dense vegetation. To address these limitations and acquire a more comprehensive understanding, additional research is essential for the accurate determination of the age structure and sex ratio on the island. Our study provides crucial baseline data for conserving this species. We recommend implementing a systematic survey encompassing the entire distribution range of the long-tailed macaque across Indonesia. Such an initiative will be instrumental in assessing its threat status and laying out a comprehensive plan for conservation efforts.

Distribution parameters of large mammals and conservation management in an Afrotropical forest landscape and biodiversity hotspot

AbstractThough there is consent that poaching is an important driver of wildlife declines in many African forests, we lack a deeper understanding of the factors behind population patterns in Afrotropical landscapes to inform conservation management. We surveyed line transects in four Cameroonian sites of different protection status in 2013/2014, namely Korup National Park, Banyang Mbo Wildlife Reserve, one timber concession and a section of an unprotected agroforestry matrix, and used data from 2007 for trend assessment. We used GLMs to identify predictors for mammal distribution based on a set of variables. While species compositions showed complex trend patterns, it is noteworthy that chimpanzee and elephant abundances declined significantly in the Banyang Mbo Wildlife Reserve. Although landscape management type affected the distribution of most mammal species, anthropogenic or environmental variables were strong predictors. Chimpanzee, elephant and drill abundances were higher at a larger distance to settlements. Vegetation density positively affected a number of species, including chimpanzee and red colobus. Several species were more abundant in rough terrain, probably because of reduced poaching. Our results suggest that protected areas in Southwest Cameroon had a mitigating effect on wildlife declines, mainly due to their remoteness and habitat quality, rather than management interventions.

Clamp-crushing Pancreatic Transection in Minimally Invasive Distal Pancreatectomy.

Minimally invasive distal pancreatectomy has become a widely accepted procedure for tumors located in the pancreatic body or tail. However, pancreatic transection by linear stapler is generally avoided for pancreatic body tumors located above the portal vein because the surgical margin width is narrowed after taking into account the cutting allowance for insertion of the stapling device. Herein, we report a parenchymal clamp-crushing procedure that provides a sufficient surgical margin in pancreatic transection. Two patients with suspected early pancreatic cancer underwent pancreatic transection using the clamp-crushing procedure. The planned pancreatic transection line was set just to the left of the gastroduodenal artery in both cases. Robotic and laparoscopic distal pancreatectomy were performed in 1 patient each. Patients were positioned supine with split legs. Parenchymal transection was performed with crushing by VIO 3 (ERBE Elektromedizin) operated in softCOAG Bipolar mode with Effect 2/modulation 50. After crushing, remnant tissue was cut in autoCUT Bipolar mode operated by VIO 3 with Effect 2/modulation 50, or cut after secured by clipping. The surgical duration was 253 and 212 minutes, and estimated blood loss was 0 and 50mL in the 2 patients, and both were discharged with uneventful courses. Pathologic examination confirmed a negative surgical margin in both patients. Clamp-crushing pancreatic transection for distal pancreatectomy might be a suitable treatment option for achieving sufficient surgical margin in pancreatic body tumors located close to the portal vein.

The Diversity of Mudskipper Fish Family Gobiidae in Mangrove Area, Seberang District, Tanjung Jabung Regency, West Jambi

Mudskipper fish (Periopthalmus spp) is a member of the order Periophthalmini, family Gobiidae and subfamily Oxudercinae. This fish is known by the names of gunshots, tempakul, timpakul and belacak. Mudskipper fish have a role as a bioindicator in mangrove ecosystems, so its existence and diversity needs to be known. This research is quantitative exploratory which aims to analyze the diversity of mudskipper fish in the mangrove area of ​​Seberang District, Tanjung Jabung Barat Regency and determine environmental factors that affect their lives. The technique for determining the sampling station was purposive sampling. Sampling was carried out at 3 stations in two different villages, namely Kuala Baru Village and Seberang Village. The survey method was conducted at 2 different stations. Each sampling station area in Seberang Village is 50 x 20 m, while in Kuala Baru village it is carried out on 2 transect lines with a transect length of 35 meters and consists of 3 plots measuring 5 x 5 m and spaced 10 m between plots. The results showed that there were 2 species of 2 general of mudskipper fish, namely Periophthalmodon schlosseri and Boleophthalmus boddarti. The most abundant type of Boleophthalmus boddarti was obtained with 36 individuals out of a total of 45 individuals. The index of diversity of mudskipper fish species at the three stations was low ranging from 0.3-0.6 and the dominance index ranged from 0.6-0.8. Environmental conditions are water temperature 31-33°C, soil temperature 28-35°C, salinity 13-15 ppt, water pH 6.8 and soil pH 6.2-6.8. DO ranges from 5.9 to 6.8 mg/L, the soil texture is clay type, dusty loam, and clay. It can be concluded that the diversity of mudskipper fish in Seberang sub-district is low, with an abundant number found in the Boleophthalmus boddarti fish species.

Health Status of Seagrass Meadows Around the Special Economic Zone (SEZ), West Likupang, North Sulawesi

Seagrass ecosystems offer valuable ecosystem services but are highly vulnerable to physical damage caused by human activities and rapid environmental change. Currently, there is very limited information available on monitoring and reporting the health of seagrass beds in Indonesian waters. This study aims to assess the species composition, density, diversity index, percentage of seagrass cover, health condition, and identification of threats to seagrass ecosystems around the West Likupang Special Economic Zone (SEZ), North Sulawesi. The method used was a seagrass watch with line transects and quadrant-shaped frames measuring 50x50 cm2. Transect lines were established through the seagrass ecosystem area at 50 m. There were three line transects at each station 25 m apart. Quadrant frame measuring 50x50 cm2. West Likupang has eight seagrass species including C. rotundata, E. acoroides, H. pinifolia, H. uninervis, H. ovalis, O. serrulata, S. isoetifolium, dan T. hemprichii. The health status of the seagrass is currently healthy, with a dense percentage of coverage. The identification of potential risks from anthropogenic activities such as the household disposal of waste at sea, gleaning, the use of boat anchors and propellers, and the construction of infrastructure in coastal areas, such as hotels and harbonurs, pose significant threats.

Amphibian community structure in Isau-Isau Wildlife Reserve, South Sumatra, Indonesia

Abstract. Tanjung RD, Kusrini MD, Mardiastuti A, Yustian I, Setiawan A, Iqbal M. 2023. Amphibian community structure in Isau-Isau Wildlife Reserve, South Sumatra, Indonesia. Biodiversitas 24: 6836-6843. Amphibian community structures in Isau-Isau Wildlife Reserve, South Sumatra, were investigated from Mei until July 2023. The data were obtained by Visual Encounter Survey combination with line transect. The data analyzed were Species Richness (Margalef Index), Diversity Index (H', Shannon-Wiener), Dominance (D, Simpson Index), and Evenness Index (J', Pielou) calculated using PAST 4.0 software. In addition, we also analyzed abiotic factors such as air temperature, humidity, water temperature, pH, total dissolved solids (TDS), and dissolved oxygen (DO). The abiotic data were included as explanatory variables in Canonical Correspondence Analysis (CCA). A total of 12 amphibian species consisting of 11 genera and 4 families were recorded. Of them, 11 species are classified as least concern, while one species, Theloderma licin, is classified as data deficient by the IUCN Red List of Threatened Species.

A weighted Weibull detection model for line transect sampling: application on wooden stake perpendicular distance data

A weighted Weibull detection model for line transect sampling: application on wooden stake perpendicular distance data

Diversity and colonization of butterfly (Lepidoptera) on Pasoso Island, Central Sulawesi

Various biotic and abiotic environmental factors influence the preservation of butterfly species in an area. The pressure and threat of extinction for butterflies that occupy relatively narrow and isolated habitats such as small islands are pretty large. This study aims to estimate the diversity of butterfly species, predict colonization, predict local extinction of butterflies, and conservation implications to minimize local extinction of butterflies in the habitat type on Pasoso Island, Central Sulawesi Province. Data was collected using field observations in four land cover types (primary forest, gardens, “ecoton” between garden-primary forests, and shrubs) on a 100 m line transect line. Each line transect is divided into point counts, with a distance between points of 100 m. The results of the identification of butterfly species in four habitat types on Pasoso Island found 16 species from 78 individual butterflies belonging to four families (Nymphalidae, Papilionidae, Pieridae, and Lycaenidae). Butterflies in all habitat types on Pasoso Island are in the moderate category. Species diversity in garden habitat types based on the analysis of the Shannon-Wiener index showed higher than other habitat types (H'=1.89), while the Ecoton habitat type has the lowest diversity value (H'=1.06). The results of the t-test showed that there was no significant difference in the diversity of butterfly species in the four habitats. The results showed that colonization and local extinction occurred in butterfly species on Pasoso Island. Four of the nine species are included in the extinct category, namely Apias albina, Family Lycaenidae, Ideopsis juventa, Phalanta alcippe celebensis Wallacea. Five other species were colonized, namely Arhopala araxes, Catochrysops strabo, Catopsilia pomona, Hypolimnas anomala, and Idea blanchardii.

Keragaman Makro Alga Berdasarkan Karakter Morfologis Di Pantai Ria Kecamatan Woja Kabupaten Dompu

sea. This study aims to find out the types of macroalgae found in Ria Beach, Woja District, Dompu Regency, to find out the Macro Diversity of algae in Ria Beach, Woja District, Dompu Regency. This study used an exploratory survey method, sampling using the Transect Line method with the Quadrant Sampling technique. Analysis of data types and utilization of research results using qualitative analysis techniques, while the level of diversity using quantitative analysis techniques, namely the index of diversity. The results of the study in the Ria Beach area, Woja District, Dompu Regency found 4 types of macroalgae, namely, Boergesenia forbesii, Ulva lactuta, Padina australis, Sargassum polycystum. The diversity of macroalgae species in the Ria Beach area, Woja District, Dompu Regency is moderate.

Using fusion effects to decrease uncertainty in distance sampling models when collating data from different surveys

AbstractEstimates of population abundance are required to study the impacts of human activities on populations and assess their conservation status. Despite considerable effort to improve data collection, uncertainty around estimates of cetacean densities can remain large. A fundamental concept underlying distance sampling is the detection function. Here we focus on reducing the uncertainty in the estimation of detection function parameters in analyses combining data sets from multiple surveys, with known effects on the precision of density estimates. We developed detection functions using infinite mixture models that can be applied on data collating multiple species and/or surveys. These models enable automatic clustering by fusing the species and surveys with similar detection functions. We present a simulation analysis of a multisurvey data set in a Bayesian framework where we demonstrated that distance sampling models including fusion effects showed lower uncertainty than classical distance sampling models. We illustrated the benefits of this new model using data of line transect surveys from the Bay of Biscay and Iberian Coast. Future estimates of abundance using conventional distance sampling models on large multispecies surveys or on data sets combining multiple surveys could benefit from this new model to provide more precise density estimates.

Avian Diversity and Abundance in Ololunga town, Narok County, Kenya

This study sought to determine bird abundance and diversity within Ololunga town, Narok County, Kenya. Using point counts and line transects, a rapid assessment of three habitats, based on levels of human disturbance was conducted. A total of 394 (n=394) birds belonging to 25 families and 34 species were recorded, with bushland recording the highest abundance and species richness (43.15%; and 26), followed by farmlands at 31.47% and 15; and human settlement recording the least (25.38% and 10). The Tukey HSD test established a significant difference in bird abundance between bushlands and human settlement areas (p = 0.014), with no significance between bushlands and farmlands (p = 0.082); nor between farmlands and human settlements (p = 0.356). Jaccard index / similarity coefficient across habitat scores noted a reducing similarity across avian sighted habitats at 0.316, 0.281 and 0.2 for human settlements-farmland; farmland-bushlands; and human settlement-bushland, respectively. Study results demonstrate that human influence has an impact on avian species composition, distribution, and abundance, especially within peri-urban areas of Narok, Kenya. Our study proposes creation of avian sensitive buffer zones within the habitats and ecotones; targeted community education on impacts of anthropogenic activities on avian diversity; and a deeper appraisal on seasonal and functional diversity in habitat types and overlapping ecotones on avian species, with a lens on resource availability.

Seagrass diversity in Pulau Banyak, Aceh Singkil District, Indonesia

Abstract. Erniati, Andika Y, Imanullah, Imamshadiqin, Erlangga, Rahmad, Tauladan TA, Siregar FR, Fitri A, Ritonga GH. 2023. Seagrass diversity in Pulau Banyak, Aceh Singkil District, Indonesia. Biodiversitas 24: 6621-6628. Seagrass is a high-level plant where life activities are submerged in seawater. Currently, the seagrass ecosystem is threatened with destruction and disappearance. The extent of seagrass ecosystems globally was estimated to have declined by about 58%. The solution to this problem is to balance local communities' utilization of biological resources and biodiversity maintenance. The biodiversity aspect of seagrass is key to the sustainability of seagrass ecosystems. Banyak Island is one of the sub-districts in Aceh Singkil Regency, which consists of a cluster of small islands and has rich fisheries and marine potential, one of them is seagrass, where station 1 is Balong Island, Stasion 2 is Balong Island, Stasion 3 is Lamun Island and Stasion 4 is Rago-Rago Island. This study aimed to assess the diversity of seagrass beds, including seagrass species composition, density, percentage cover, and water quality that affect the existence of seagrass ecosystems. This study used a purposive sampling method with 3 transect lines spaced 50 m perpendicular from the shoreline to the sea. Each transect line has 5 plots with a distance of 10 meters measuring 50 x 50 cm2, and the water quality parameters were measured in situ. This research found 5 seagrass species, namely T. hemprichii, C. rotundata, E. acroides, S. isoetifolium, and H. ovalis. C. rotundata is the species with the highest density on Matahari Island, but seagrass diversity is low, and no species were dominant in the groups. The results of PCA analysis showed that the environmental factors that most influenced the pattern of seagrass distribution and density were nitrate, phosphate, and substrate. The conclusion revealed that seagrass diversity on Banyak Islands is relatively low.

Ecological conditions of Javan langur (Trachypithecus auratus É. Geoffroy Saint-Hilaire, 1812) in Sokokembang Forest (Central Java, Indonesia) through distribution and food preferences

Javan langur (Trachypithecus auratus) is endemic to Java Island with vulnerable conservation status according to IUCN. The study aimed to determine the distribution and food preferences of Javan langurs in Sokokembang Forest as part of understanding ecological conditions. The research used strip transect and concentration count methods, sampling the distribution of food using accidental sampling and recording data on the utilization of food plants with rapid assessment. The results showed that the types of food consumed by javan langurs were 14 types of plants, which were scattered at 6 points on five transect lines. The percentage of preferred plants was (Pangium edule) 29.4%, (Artocarpus elasticus) 17.6%, (Dysoxylum excelsum) 11.8%, (Pometia pinnata) 8.8%, (Cinnamomum iners) 5.9%, and others 2.9%. The average vertical space utilization of javan langurs during feeding activities was 17.3 m (stratum C) with a percentage of 70.6%. The percentage of tree crown space usage pattern of javan langur in CII (36.1%), CI (19.4%), BII (13.9%), AI (11.1%) BII, and CIII (8.3%), AII (2.8%). Food type and tree crown space are important parts of the presence of Javan langurs in Sokokembang.