White shrimp is one of the largest artisanal capture fisheries commodities in Demak. The utilization of these shrimps often overlooks their species category as they are mostly white in appearance. Growing trend of shrimp fishing may affect shrimp management due to population declination to the genetic level since the genetic data are insufficient. Hence, we aim to identify and study the genetic diversity of white shrimp caught in Demak Waters to provide an overview as a reference for fishery improvement project. A random purposive sampling method was used to collect a total of 90 white shrimp specimens from four fishing grounds (Babalan, Gojoyo, Menco, and Seklenting) in the Demak Waters. Specimens were extracted using Chelex 10%, amplified using PCR, and sequenced by the Sanger method based on the mtDNA COI gene. This research revealed the presence of five species of white shrimp: Penaeus merguiensis, Fenneropenaeus penicillatus, Penaeus vannamei, Metapenaeus brevicornis, and Metapenaeus ensis. The genetic diversity studies were continued using the Penaeus merguiensis species only. The results showed 17 haplotypes with a genetic diversity (Hd) of 0.6936 and a nucleotide diversity of 0.00108, which express moderate genetic diversity. Population analysis using Analysis of Molecular Variance (AMOVA) indicated a non-significant difference between the four study populations (panmictic population) with an FST value of 0.00756 (P-value < 0.05). Based on these results, an adequate management of stock is important. For instance, an open-closed season is needed in order to sustain and reduce capture pressure on the white shrimp population in Demak waters.
The variability of Sea Surface Temperature (SST) and chlorophyll-a distribution in the southern waters of East Java is heavily influenced by the Indian Ocean Dipole (IOD) phenomenon. This study examines oceanographic parameter variability, their relationship with the IOD from 2003 to 2014, and fishing dynamics in the southern waters of East Java, particularly at PPN Prigi. Data utilized include SST and chlorophyll-a from Aqua-MODIS satellites, the Dipole Mode Index (DMI), and 12 years of fish production records. The analysis reveals significant fluctuations in SST and chlorophyll-a, with a strong inverse relationship (correlation: –0.677), where chlorophyll-a concentrations rise as SST decreases. Positive IOD events reduce SST, while negative IOD events increase SST, with correlations of –0.591 for SST and IOD and 0.601 for chlorophyll-a and IOD. During the positive IOD events of 2006–2008, SST decreased, leading to increased fish production. Conversely, the negative IOD in 2010 raised SST, contributing to a decline in fish stocks. Over the 12-year period, a notable increase in Bali Sardinella and skipjack production was observed, despite a sharp decrease in 2010 caused by higher SST levels. This study highlights the importance of understanding the interactions between SST, chlorophyll-a, and IOD in developing sustainable fisheries management strategies. These insights can support efforts to optimize fish resource utilization, mitigate the impacts of climate variability, and ensure long-term fisheries productivity in the southern waters of East Java, particularly for strengthening adaptive resource planning within climate-sensitive pelagic ecosystems and supporting informed decision-making for regional fisheries policies and sustainable blue-growth initiatives.
Kaimana and Fakfak are two regions in West Papua which have high biodiversity. The total fish production in Kaimana and Fakfak are 10,039 tons.y-1 and 17,806 tons.y-1, respectively. The snapper fish (Lutjanus spp.) is one of the important economic commodities in Kaimana and Fakfak regions. There has been a decrease in the number of exports of snapper fish in 2018 to 2019 from 4,742 tons to 4,290 tons due to overfishing and environmental pollution. This study employed DNA barcoding technology to identify the species of snapper fish collected from Kaimana and Fakfak. The DNA isolation was conducted by using genomic DNA mini kit (tissue) and the amplification of COI gene with Go Taq green master mix. Agarose gel electrophoresis was used to visualize the PCR product. A total of 16 sequences with length 654 base pairs of COI gene were identified as five species of Lutjanidae, which were Lutjanus decussatus, L. gibbus, L. quinquelineatus, L. malabaricus, and L. johnii. Homology analysis with BLAST NCBI and BOLD System showed that all samples have similarity of 99.08-100% and query cover of 93-100%. Relationship analysis using phylogenetic tree and genetic distances showed results of intraspecific close relatives (0.001-0.016) and interspecific distant relatives (>0.1000). The phylogenetic tree illustrated that all species of Lutjanidae are separated into monophyletic clades. DNA barcoding technology successfully identified the snapper fish collected from Kaimana and Fakfak.
In this study, samples were collected from three areas of the Iraqi marine environment, where fish are caught to be marketed to local markets for use as food. The study area includes coral reef, Khor Abdallah, as well as Um Qaser Port. Using the closed cylinder technique with Solid State Nuclear Track Detector (SSNTDs) CR-39. The concentration of Radon-222 was measured, as well as the radium equivalent, in addition to the emission per unit area and the emission per unit mass. The results are arranged by region as follows: In the Coral Reef, the lowest value was found in the bivalve Corbicula and was 14.01±4.68 Bq.m-3, while the highest concentration of Radon-222 gas isotope value was in the shrimps; 69.52±19.33 Bq.m-3 , with an average value of 28.69±9.1 Bq.m-3. In Kohr Abdallah, the lowest concentration of Radon-222 gas isotope value was found in the Laevicardium sample, it was 16 Bq.m-3 , while the highest value was in the Shrimps too, which was 61 Bq.m-3. This value is close to the value of the shrimps in the coral reef area, with the average value 37±11.2 Bq.m-3. In the Um Qaser area, the lowest concentration of Radon-222 9.93±3.76 Bq.m-3 was found in Cerithium scabridum whereas the highest value was 29.03±8.84 Bq.m-3 and found in the Anemones sample. Based on the measurements taken in this study, in which the concentration of radioactive Radon-222 isotope was calculated, it appears that the measured concentration values are within the acceptable range, and therefore the use of these samples does not pose a risk if used.
Litopenaeus vannamei is a key species in global aquaculture; however, its susceptibility to vibriosis presents a persistent challenge. The aim of this study was to investigate the effects of dietary supplementation with alginate and Spirulina hot water extract (SWE) on the immune response and gene expression associated with pathogen resistance. Shrimp fed diets containing 3 g·kg⁻¹ of alginate and 5 mg·kg⁻¹ of SWE exhibited marked improvements in immune parameters, including total hemocyte count, phagocytic activity, phagocytic index, phenoloxidase activity, and superoxide dismutase levels, as measured on days 3 and 7 (P< 0.05). Following challenge with Vibrio parahaemolyticus, V. vulnificus, and V. harveyi, treated shrimp demonstrated a 90% survival rate compared to 0% in the control group. Gene expression analysis revealed a 2-fold and 1.5-fold upregulation of prophenoloxidase (proPO) and lipopolysaccharide β-glucan binding protein (LGBP), respectively, indicating the activation of the proPO cascade and pathogen recognition pathways. These results provide direct evidence that alginate and SWE act as immunostimulants by modulating hemocyte function and immune-related gene expression. The findings of the present study suggest that oral supplementation with these natural bioactive compounds can serve as a functional dietary strategy to enhance disease resilience in shrimp and promote more sustainable aquaculture systems, in seven days period.
The Totok and Makalo River estuaries in North Sulawesi, Indonesia, serve as vital habitats teeming with fish biodiversity, supporting coastal ecosystems and local fisheries. This study aimed to identify fish species and elucidate their genetic relationships through DNA barcoding of the Cytochrome Oxidase I (COI) gene. Fish samples were collected from both estuaries using nets and traps, followed by molecular analysis involving polymerase chain reaction (PCR) amplification and Sanger sequencing. The results confirmed the presence of 11 fish species, including Osteomugil engeli, Polydactylus plebeius, and Gazza minuta, with high identification accuracy (over 98% sequence similarity to reference databases). Notably, Paracentropogon rubripinnis and Nematalosa come were recorded for the first time in North Sulawesi waters, expanding the known distribution of these species. Significant genetic variation was detected in P. rubripinnis, potentially indicating cryptic speciation or local adaptation to environmental gradients. Phylogenetic analysis revealed close genetic affinities between certain species and populations from Taiwan and Bangladesh, suggesting historical migration patterns or shared ancestry, possibly facilitated by ocean currents. These findings underscore the rich genetic diversity in these estuaries, which are influenced by factors like salinity, temperature, and anthropogenic pressures. The study emphasizes the urgency of conservation strategies, including habitat protection and sustainable fishing practices, to preserve biodiversity and maintain ecosystem services. By providing baseline data on species composition and genetic connectivity, this research contributes to broader efforts in marine biodiversity monitoring and informs policy for coastal management in Indonesia's biodiversity hotspots.
Cancer remains a major global health problem, prompting continuous exploration of marine organisms as sources of novel bioactive compounds. This study evaluated the cytotoxic and apoptosis-inducing activities of F9 and F10 fractions obtained from methanolic extracts of sea cucumber (Stichopus sp.) against the human hepatocellular carcinoma cell line HepG2 as an in vitro cancer model. Sea cucumber samples were extracted using methanol maceration and subsequently fractionated through Medium Pressure Liquid Chromatography (MPLC) to obtain bioactive fractions. Cytotoxic activity was assessed using the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay after 24, 48, and 72 h of incubation to determine cell viability. Apoptotic effects were examined using Annexin V and propidium iodide (PI) staining, followed by fluorescence microscopy to evaluate morphological changes associated with apoptosis. The results demonstrated that both fractions exhibited significant cytotoxic effects on HepG2 cells in a time-dependent manner, with IC50 values of 14 µg.ml-1 for the F9 fraction and 23 µg.ml-1 for the F10 fraction after 72 h of treatment. Among the tested fractions, F9 showed stronger cytotoxic activity at lower concentrations. Morphological observations revealed typical apoptotic characteristics such as cell shrinkage, membrane blebbing, nuclear condensation, and phosphatidylserine externalization, indicating apoptosis as the predominant mechanism of cell death. These findings demonstrate that Stichopus sp. contains bioactive compounds with anticancer potential. This study highlights the importance of marine invertebrates as natural resources for biomedical applications and supports the development of marine biotechnology strategies for cancer therapy. Further investigations are needed to identify the active compounds responsible and clarify their molecular mechanisms of action.
Sea cucumbers (Holothuria leucospilota) have significant potential as sources of antibacterial compounds. These organisms live in association with bacteria that produce secondary metabolites exhibiting biological activities similar to those of their hosts, including antibacterial effects. Acne is an inflammatory condition that can be exacerbated by acne-causing bacteria such as Staphylococcus epidermidis and Propionibacterium acnes. Although antibiotics are commonly used for treatment, their effectiveness has increasingly been compromised by the emergence of antibiotic resistance. Bacteria associated with H. leucospilota therefore represent a promising alternative source of antibacterial agents due to their ability to produce bioactive secondary metabolites. This study aimed to characterize the macroscopic and microscopic diversity of these bacteria, evaluate their antibacterial activity against S. epidermidis and P. acnes, and analyze the chemical profiles of their ethyl acetate fractions. Bacterial isolation was conducted using Sea Water Complete Agar (SWCA), and antibacterial activity was assessed using the TLC bioautography method with iodonitrotetrazolium chloride (INT) as a growth indicator. A total of 12 bacterial isolates were obtained, comprising 10 isolates from the internal tissues and 2 isolates from the external surface of H. leucospilota. Antibacterial screening showed that 11 of the 12 isolates were active against S. epidermidis, while 8 isolates exhibited activity against P. acnes. Phytochemical screening indicated that phenolic and terpenoid compounds were the bioactive constituents responsible for the observed antibacterial activity.
Limited feed availability is one of the major challenges in scaling up lobster aquaculture in Indonesia. At present, most lobster farmers rely heavily on trash fish, mainly sardines, which are nutritionally unbalanced, compete with human consumption, and are subject to seasonal fluctuations in price and availability. This study evaluated the use of earthworms as an alternative feed for juvenile scalloped spiny lobster (Panulirus homarus), assessing their nutritional value and effects on growth, survival, and immune responses. A 63-day feeding trial was conducted with four treatments and three replicates per treatment: 100% fish (Control), 70% fish + 30% earthworm (R7C3), 30% fish + 70% earthworm (R3C7), and 100% earthworm (C10). Hemolymph samples were collected to analyze total hemocyte count (THC) and phenoloxidase (PO) activity alongside growth measurements. Lobsters fed earthworm-based diets (C10, R3C7, and R7C3) exhibited significantly higher specific growth rates (0.98–1.73%/day) compared with the control (0.42–0.59%.day-1). Survival followed a similar pattern, with markedly higher rates in earthworm-fed groups (60–75%) than in the control (~25%). Immune parameters, including THC and PO activity, were significantly elevated in lobsters receiving earthworm diets. These findings demonstrate that earthworms are a promising, sustainable feed alternative that improves growth, survival, and immunity in P. homarus, reducing dependence on trash fish in lobster aquaculture.
The valorization of marine by-products represents a promising approach for discovering novel bioactive compounds. This study presents a comparative phytochemical and bioactivity assessment of shrimp shell waste extracts from Parapenaeus longirostris and Aristeus antennatus species, which are prevalent on Algerian coasts. The objective of this study is to evaluate their potential as a source of biologically active compounds, with a particular focus on those compounds that possess anti-inflammatory and antidiabetic properties. The methodology entailed the extraction of chemical compounds. The subsequent procedure involved the utilization of shrimp residues, which were then subjected to a comprehensive compositional analysis. This analysis was then followed by an evaluation of their biological activity. The results obtained demonstrated the presence of biologically effective compounds, with the extracts exhibiting notable anti-inflammatory and antidiabetic activity. White shrimp (P. longirostris) was found to be particularly efficacious in both activities, showing particular promise in diabetes-related inhibition. This finding indicates the potential of valorization. It is evident that these marine by-products have the potential to serve as a promising natural resource for the development of value-added products. It is evident that these initiatives facilitate novel advancements in the domains of health and industry, thus underpinning the blue economy within the paradigm of sustainable development.
The Holocene epoch was marked by significant climatic fluctuations that shaped marine productivity across tropical coasts. This study reconstructs Holocene paleoproductivity along the East Coast of Peninsular Malaysia, specifically Terengganu (TER16-GC13C) and Kelantan waters (KELC17) using core sediments. A multi-proxy approach was applied, analysing biogenic silica (BSi), total organic carbon (TOC), calcium carbonate (CaCO₃), and elemental ratios (Ca/Al, Ca/Fe, Ba/Al) to evaluate changes in productivity in response to sea-level and monsoonal variability. Results indicate distinct temporal patterns: the early Holocene showed elevated BSi and TOC linked to enhanced nutrient influx during rapid sea-level rise. While the mid-Holocene exhibited reduced carbonate deposition due to strong terrigenous input associated with the East Asian Summer Monsoon and the late Holocene was marked by increased CaCO₃ deposition reflecting reduced riverine input and greater biogenic production during sea-level highstand decline. Elemental ratios corroborate these shifts, highlighting the dynamic interplay between terrigenous and marine sources.These findings demonstrate that sea-level change was a dominant driver of productivity variations, modulated by monsoonal strength. The strong correlation between terrigenous proxies and grain size underlines the role of hydrodynamics in sediment delivery. This study contributes an integrated Holocene paleoproductivity reconstruction for East Coast Peninsular Malaysia, providing a regional baseline that complements South China Sea records. The results enhance understanding of tropical shelf ecosystem sensitivity to climate variability, offering a reference framework for assessing future climate change impacts on coastal productivity.
Eutrophication poses a significant challenge in Indonesian waters, largely due to a lack of data for effective mitigation. This complex issue, characterized by a time lag and multi-phase progression, is triggered by an influx of nutrients like nitrate and phosphate, leading to harmful algal blooms (HABs) that degrade water quality. This study proposes a more comprehensive approach using the Trophic Index (TRIX), which integrates multiple parameters from the PISCES global biogeochemical model data. The PISCES model accurately captures seasonal TRIX trends, with high values in the southern islands during the southeast monsoon and in northern areas during the northwest monsoon. The model's reliability is confirmed by RMSE and Bias data to be quite low, respectively, for Chl-a (0.065, -0.005), Nitrate (0.144, -0.080), Phosphate (0.084, -0.059), and DO (3.109, 0.919), from the World Ocean Database. The highest TRIX values (8-10) were found in Jakarta Bay, while the Lombok Strait had values (5-7), a difference attributed to varying oceanographic conditions. However, it is crucial to consider physical oceanography and boundary conditions when using the TRIX model. So then, model TRIX data is more valuable for informing policy and mitigation plans for the various Indonesian waters, taking into account their unique characteristics. These findings underscore the importance of considering both monsoon cycles and local conditions when assessing eutrophication risk. The TRIX data is therefore a valuable tool for developing informed policies and mitigation plans for Indonesia's diverse coastal areas.
Groupers (Family Serranidae) are well known as top predators in the coral reef ecosystem. This family is one of the most important ecological organisms in the food web at Raja Ampat reefs. The aim of this study, therefore, was to investigate the food composition as well as the inter and intra-specific competition of two Serranidae species, including Epinephelus malabaricus and Epinephelus areolatus in Waisai, Raja Ampat. This study is expected to fill gaps on groupers food preferences. A total sample were collected at the fish landing site was 6 fish (2 sample of Epinephelus areolatus and 4 sample of Epinephelus malabacrius). DNA Amplification was performed using the COI mithocondrial gene marker (HCOI12198 and LCOI1490 primers). Bioinformatics and data analysis using QIIME 2 and R Software. This further comprised of α and β diversities. The results showed that Serranidae diet composition comprise of 13 species. Epinephelus malabaricus species demonstrated more diet composition varieties than Epinephelus areolatus. The most abundant diet found in all fishes’ gut samples was come from Scianidae family. The results indicate that there is an absence of any interspecific competition between the two species studied, due to a wide variation of diet composition. Conversely, intraspesific competitions existed amongst the Epinephelus malabaricus niches. This study highlighted DNA Metabarcoding application in trophic level and food web studies, as well as facilitating the development of information for ecological references.
Abalone (Haliotis squamata) is a high value marine mollusk with significant aquaculture potential in Indonesia. However, the production of this species faces major constraints, especially during the grow-out phase, due to high juvenile mortality during transport, primarily caused by hypoxic stress. This study investigated the effect of high carbohydrate diets on the physiological response and survival of juvenile abalone under simulated dry shipping-induced hypoxia. A total of 120 juveniles were fed five diets (Gracilaria sp. as a control, and formulated feeds with 25%, 35%, 45%, and 55% carbohydrate content) for 30 days prior the hypoxia treatment. The juveniles were then subjected to hypoxic conditions for 6, 12, and 24 h. All abalones survived the feeding period, but only individuals fed with 55% carbohydrate survived after 24 h of hypoxia. Abalones receiving 45% and 55% carbohydrate diets showed the highest protein and carbohydrate accumulation, respectively. Biochemical analysis revealed that hypoxia triggered a decrease in protein content, stable lipid levels, and fluctuating carbohydrate reserves. These results highlight the critical role of carbohydrates in supporting abalone under hypoxic stress and suggest that carbohydrate enriched diets could reduce mortality during dry transport and improve aquaculture outcomes.
Indonesia, with its second-longest coastline in the world, is vulnerable to coastal disasters such as extreme waves and coastal abrasion. Pesisir Barat Regency in Sumatra is one of the regions that is vulnerable to these threats. Extreme waves, although rarely occur because of tropical cyclones, can be triggered by the influence of cyclones in the Indian Ocean. In addition, coastal abrasion caused by the interaction of waves, currents, and winds is increasingly threatening coastal areas. This research aims to identify the risk of extreme waves and abrasion disasters in Pesisir Barat Regency using a research-based approach to Geographic Information Systems (GIS) and multi-criteria analysis. Data on marine hydrodynamics, coastal topography, and land cover conditions are integrated to produce disaster risk maps. The risk analysis results show that the Ngaras sub-district and several other sub-districts, such as Bangkunat, Lemong, and Ngambur, have a high level of risk, with a total risk area reaching 0.398 square kilometers (km2). Meanwhile, most other sub-districts are in the low-risk class. Key factors influencing the risk level include coastal topography, vegetation cover, and the intensity of human activities in coastal areas. This study highlights the importance of coastal zone management based on risk mitigation and the need to protect coastal ecosystems to reduce disaster impacts. The findings are expected to serve as a reference for disaster mitigation policy planning in Pesisir Barat and other coastal areas. Additionally, these results could be utilized to develop holistic and practical disaster reduction effort by related stakeholders and coastal communities.
The Indonesian Maritime Continent is highly vulnerable to climate variability and change, as exemplified by tidal flooding events in the Riau Islands from 2022 to 2024. This study aimed to analyze the characteristics of sea level dynamics and anomalies associated with tidal flooding (rob) and identify the contributing factors. Data on tidal flooding events were gathered from press and online social media reports, while additional information on significant wave height, ocean currents, and wind was obtained from the CMEMS (Copernicus Marine Environment Monitoring Service) Marine Copernicus archives (marine.copernicus.eu). Observational data from tide gauge stations were also accessed via the IOC sea level monitoring system (ioc-sealevelmonitoring.org). The findings revealed a high probability of tidal flooding during the north wind season, particularly in January and February. Notably, tidal elevations during flooding events reached 3.06 m on January 25, 2023, 3.00 m on February 21, 2023, and 3.09 m on February 12, 2024. These events were driven by a combination of oceanographic and atmospheric factors, including high tidal ranges during spring tides, strong wind speeds averaging 19.04 to 21.43 knots in January–February 2023 and 18.65 knots in February 2024, dominant southward current patterns, and significant wave heights reaching up to 1.08 m. The alignment of the sun, moon, and earth during full and new moon phases amplified gravitational forces, causing elevated sea levels. Furthermore, strong winds during the north wind season contributed to higher wave heights, intensifying flooding impacts. Analysis of current patterns indicates that the highest speeds were recorded during the northern wind season, specifically in January and February, which coincides with the tidal flooding events. The currents predominantly moved southward, aligning with the wind direction during this season. This study reveals oceanographic and atmospheric interactions driving tidal flooding, offering insights for mitigation and adaptation to enhance resilience in vulnerable coastal regions.
Recently, there has been a global decline of coral reef ecosystems, primarily caused by major threats such as global warming. This phenomenon has a significant negative impact on coral reefs, including rising sea temperatures that trigger of coral bleaching. Composition of symbiotic algae, Symbiodiniaceae, in corals determines how corals respond to environmental stress. This study aimed to investigate the community of the symbiotic algae during bleaching event by applying molecular identification technique. Coral bleaching samples from different genera were randomly collected from three different location around Sambangan Island, Karimunjawa at the depth of 1 – 2 m. DNA Barcoding of Internal Transcribed Spacer (ITS1, 5.8 rRNA and ITS2) gene were performed. Our result shows that four types of Symbiodiniaceae were closely related to the symbiotic algae found in this study, i.e. Cladocopium goreaui, Cladocopium sp., Symbiodinium sp. Clade C, and Symbiodinium sp. C1. The phylogenetic tree analysis showed that all the Symbiodiniaceae species found formed a single clade with a low genetic distance value. All of these species belong to the same genus Cladocopium. This type of symbiotic algae is known to have broad tolerance to temperature changes and other stress factors.
Mangrove ecosystems are crucial for sustaining tropical coastal environments and play a vital role in climate change mitigation through their capacity to sequester and store blue carbon in both vegetation and sediment. Despite their ecological value, mangroves in Jakarta Bay are under increasing pressure from coastal development, land conversion, pollution, and unsustainable exploitation. These anthropogenic threats reduce mangrove cover and diminish their ability to function as carbon sinks. This study examined mangrove carbon stocks at four locations Muara Village, Kapuk Muara, Marunda, and Muara Jaya Village through vegetation surveys, biomass measurement, and the calculation of the Important Value Index (IVI) to analyze species composition and dominance. The results demonstrated considerable variation in biomass and carbon reserves across sites. Muara Village recorded the highest biomass (558.72 tons ha⁻¹) and carbon stock (262.59 tons ha⁻¹), followed by Kapuk Muara (411.18 tons ha⁻¹), Muara Jaya (365.39 tons ha⁻¹), and Marunda, which had the lowest values (208.9 tons ha⁻¹). Dominant species included Rhizophora mucronata and Avicennia marina, reflecting their ecological adaptability and contribution to blue carbon storage. The findings emphasize that mangrove areas with higher biomass and carbon reserves are critical for maintaining ecosystem resilience in Jakarta Bay. Conservation and restoration should therefore prioritize sites with strong carbon storage potential, while degraded areas require rehabilitation to enhance ecological services. Strengthening mangrove management will not only support biodiversity and coastal protection but also contribute significantly to regional climate change mitigation strategies through the preservation of blue carbon.
The Donan Creek is a coastal ecosystem in Central Java that is strongly affected by industrial activities. This study represents the first attempt to use the polychaete worms Diopatra claparedii Grube, 1878 (Onuphidae) as a bioindicator of heavy metal contaminations. The work was conducted between July and September 2023 at four sampling sites, designated from the farthest to the closest to the Indian Ocean. Samples of D. claparedii, sediment and water were collected at each site during low tide. The samples were analyzed for Cd, Cr and Pb concentration using Atomic Absorption Spectrophotometry. In addition, several other environmental parameters were also measured to examine the water quality of the creek. Our study highlights the capability of D. claparedii to accumulate all the three heavy metals. The concentrations of Cd, Cr and Pb in the body tissues of the worms ranged from 29.743 ± 0.011 mg.kg-1 to 50.036 ± 0.028 mg.kg-1, from 21.718 ± 0.024 mg.kg-1 to 40.032 ± 0.052 mg.kg-1, and from 20.068 ± 0.008 mg.kg-1 to 44.030 ± 0.000 mg.kg-1, respectively. These amounts were so far the highest among all other aquatic animals (i.e. bivalves, crustaceans and fishes) used as bioindicators in the Donan Creek. The heavy metal concentrations in D. claparedii were significantly correlated with those in the sediment (p < 0.05). In general, the levels of the metals were considerably higher in the more industrial area than those of the less industrial area (P<0.05). We further found that the concentrations of Cd, Cr and Pb as well as several other environmental parameters including BOD, COD, the total nitrate and phosphate in the water column of the creek did not meet the water quality standards stipulated by the Indonesian Government. These findings indicate that the ecosystem has been polluted by both heavy metals and organic matters. While environmental remediation is urgently required, a comprehensive review and improvement of industrial and domestic waste management practices in the region are equally essential to prevent further degradation.
This research examined the post-rehabilitation dynamics of the mangrove ecosystem in the Mangrove and Crab Conservation Area, Tarakan, North Kalimantan, four years after the launch of a community-based restoration program in 2019. The objectives were to evaluate species composition, vegetation structure, and the survival of mangrove seedlings within rehabilitated plots. The sampling was done on purpose in areas that show the main ecological features of the site. This study found five types of mangrove trees: Avicennia alba, Rhizophora mucronata, Avicennia marina, Sonneratia alba, and Xylocarpus granatum. It is fewer than the ten species that were there in the past. Among these, Avicennia alba consistently dominated both the mature and seedling stages, recording the highest relative density (72.56%), frequency (42.86%), and canopy cover (78.08%). Its naturally regenerating seedlings reached a survival rate of 52%, substantially higher than the 17% recorded for planted Rhizophora mucronata. The Avicennia alba is particularly well adapted to the prevailing site conditions, mainly owing to its tolerance of sediment disturbance and variable salinity. This outcome highlights the importance of Assisted Natural Regeneration (ANR) that employs locally adapted species, offering a more practical, cost-effective, and sustainable approach than conventional planting methods. Although there have been some improvements, the decrease in species numbers shows the ecosystem is still in the early stages of recovery. To make sure it stays healthy and strong for the future, it is important to keep the water flowing properly, reduce human impact, and keep up with regular checks and monitoring.
