Coastal Areas Research Articles

Optimal configuration of integrated energy system considering heat enhancement and combined operation of low head seawater pumped storage and reverse osmosis

The remote coastal areas face difficulties due to energy shortages and insufficient freshwater resources. To reduce the energy consumption of reverse osmosis desalination in coastal areas, this paper proposes an optimal configuration method of integrated energy system considering heat enhancement and combined operation of low-head seawater pumped storage and reverse osmosis. Firstly, the heat analysis of power to gas and the construction of the reverse osmosis temperature model considering heat enhancement are carried out, utilizing its reaction heat to preheat the reverse osmosis feed. Secondly, the reverse osmosis feed is supplied from the upper reservoir of the low-head seawater pumped storage, allowing the operating pressure of the reverse osmosis to be met by both the hydrostatic pressure of the upper reservoir and the high-pressure pump. Furthermore, the working efficiency of the reversible turbine is modeled by considering the operational characteristics of the seawater pumped storage. Then, a bi-level mixed-integer optimal configuration model with annual total cost and wind abandonment rate as evaluation indexes is established and solved. The results indicate that compared to the conventional system, the proposed system achieves a reduction of 4.30 % in annual total cost and 2.46 % in wind abandonment rate, resulting in more pronounced economic advantages and higher renewable energy utilization. Furthermore, the energy consumption of reverse osmosis is decreased by 26.62 %, and the energy utilization ratio of the seawater pumped storage is increased by 9.81 %, demonstrating superior performance in system energy efficiency.

The function of the Wadden Sea in the life cycle of small pelagic fish

Most fish species require different habitats to complete their life cycle, with coastal areas often playing a crucial role as nursery areas for juveniles. The Wadden Sea is an important nursery area for juvenile fish in the North Sea ecoregion. Despite extensive research on the nursery function of the Wadden Sea for demersal species, its role in the life cycle of small pelagic fish (SPF) remains largely unknown. This limits our understanding of the Wadden Sea ecosystem, as SPF are the dominant component of the overall fish biomass and serve as important food source for higher trophic levels. We studied the role of the Wadden Sea in the life cycle of Atlantic herring (Clupea harengus), European sprat (Sprattus sprattus), European smelt (Osmerus eperlanus) and European anchovy (Engraulis encrasicolus) through monthly stow net and seasonal trawl surveys. Our study showed that SPF use the Dutch Wadden Sea primarily as juvenile habitat, with herring being the dominant marine juvenile representative. Length frequency distributions and genetic analysis revealed that the juvenile herring originated predominantly from southwestern waters, such as the English Channel. Additionally, the Wadden Sea still provides spawning grounds for herring and anchovy, with no substantial spawning observed for sprat. While smelt can complete nearly its entire life cycle in the Wadden Sea, it depends on connectivity to nearby freshwater for spawning. In summary, the Wadden Sea functions as a nursery for juveniles, and to a lesser extent as spawning grounds for adults. A thorough understanding of these functions is crucial for identifying bottlenecks and implementing effective conservation and management strategies.

New saga in Finland: The rise of Diplodia sapinea in scots pine.

The intensity of fungal virulence is likely to increase in northern forests as climate change alters environmental conditions, favoring pathogen proliferation in existing ecosystems while also facilitating their expansion into new geographic areas. In Finland, Diplodia sapinea, the causal agent of disease called "Diplodia tip blight", has emerged as a new pathogen within the past few years. To reveal the current distribution of the novel fungal pathogen, and the effect of temperature and rainfall on its distribution, we utilized citizen science for the detection and collection of symptomatic Scots pine (Pinus sylvestris) shoots. The Finnish culture collection of D. sapinea was initiated using in vitro cultured symptomatic samples, and selected strains were studied for their virulence and disease cycle. Furthermore, the mycobiome of selected symptomatic and asymptomatic Scots pine shoots was studied using amplicon sequencing and the presence of D. sapinea was confirmed with culturing, qPCR, and species-specific PCR. Based on over 500 Scots pine shoots testing positive for D. sapinea, the distribution of this fungal pathogen is concentrated along the coastal areas of Finland, extending up to 200 km inland from the coastline. The observed presence of D. sapinea followed the period of highest average temperatures recorded in Finland in 2023 and was also found to be related to less precipitation. The amplicon sequencing showed that abundance of D. sapinea was higher in the healthy tissues of symptomatic shoots compared to visually healthy shoots. Similarly, the abundance was higher in samples collected from coastal areas in Southwestern Finland, which are the most heavily impacted by this disease. Here, we show that the presence of D. sapinea is more extensive than previously assumed, and lastly illustrate the hypothesized disease cycle of the fungal pathogen in Finland based on observations made in the field from 2021 to 2024 and in vivo and in vitro studies.

Integrative oxidative stress biomarkers in gills and digestive gland of the combined exposure to citalopram and bezafibrate with polyethylene microplastics on mussels Mytilus galloprovincialis.

Pharmaceutical active compounds (PhACs) and microplastics (MPs) have been detected in different marine compartments from coastal areas, raising concerns due to their simultaneous discharge through wastewater treatment plants (WWTPs) and the role of MPs as vectors of pollutants for marine organisms. This study investigates the biochemical effects of citalopram (CIT) and bezafibrate (BEZ) on the mussel Mytilus galloprovincialis, at environmentally relevant concentrations, and their co-exposure with high-density polyethylene (HDPE) MPs. MPs accumulated in gills and digestive glands during exposure, but they were rapidly eliminated after depuration, except for a small fraction of the smallest MPs in gills. This study evaluated the biological effects in gills and digestive gland, and confirmed CIT induced oxidative stress in both tissues, exacerbated by the presence of MPs. BEZ, despite not being detected at high concentrations in the mussel tissues, activated an antioxidant response in gills and increasing the transcription of the genes Se-gpx and gst-pi in digestive gland. Both PhACs impaired the cholinergic pathway long-term, even after the depuration period, as indicated by decreased AChE levels in the gills, suggesting potential neurotoxic effects after prolonged exposure. Consequently, adverse effects were provoked by both PhACs with (CIT) and without (BEZ) significant bioaccumulation capacity.

A multi-compartment monitoring approach to assess the impact of marine litter in a Mediterranean coastal area.

Marine litter, particularly microplastics, is a growing threat to the Mediterranean Sea, impacting biodiversity and ecosystem health. However, most studies conducted in the Mediterranean Sea have focused on monitoring of only specific environmental compartments, and rarely have highlighted the overall impacts affecting an area. Therefore, using a new multi-compartment monitoring approach and a standardized methodology, this study investigates the abundance, distribution, composition and impact of marine litter on beaches, surface waters, fish and mussels in a coastal area of Tuscany (Italy). Concerning beach macro litter values, significant differences were found among the three beaches analysed, with the highest amount in the Feniglia beach (mean value=1245items/100m). The top items found are cotton bud sticks (32.3%), which in the winter survey at Feniglia beach, reached a remarkable density of 1983items/100m. Microlitter (1-5mm), was detected in the beach sediments with a mean abundance of 130items/m2. Regarding floating macrolitter, the transect with the highest values was the Feniglia site at 3nauticalmiles in autumn (1083items/km2) while for floating microlitter the highest concentration (832,683MPs/km2) was found in front of Scarlino. Of the 234 fish analysed from 5 different species, 67 contained microplastics in the gastrointestinal tract (28%) with a mean value of 0.4 items per individual. The species with the highest occurrence was the European anchovy (Engraulis encrasicolus) (53%) followed by the bogue (Boops boops) (40%). Through the application of the Marine Litter Impact Index (MLII), considering all the compartments analysed, the Feniglia area emerges as the ecosystem most impacted by marine litter (mean MLII=3.5, high). This study highlights how a multi-compartment monitoring approach is crucial for understanding the complex interactions between land, sea, and biota.

Mercury bioaccumulation and assimilation in marine plankton in meltwater influenced fjords and shelf waters along the east coast of Greenland.

The rapid melting of the Arctic cryosphere due to climate change will result in significant freshwater input into Arctic marine ecosystems. This might also cause the release of legacy mercury (Hg) stored in the cryosphere, increasing Hg concentration and its subsequent effects on the marine biota. However, there is scarce knowledge on the concentration of Hg in the lower trophic level organisms at the base of the Arctic pelagic food web. This is particularly important since these organisms modulate the transfer of Hg to higher trophic levels, including fish and marine mammals. We quantified the Hg concentration in two plankton size classes (> 200 and 50 – 200 μm) in coastal waters along the east Greenland coast and investigated the potential assimilation efficiency of both inorganic Hg (IHg) and methyl Hg (MeHg) in mesozooplankton and their faecal pellets in experimental incubations. The concentration of Hg in plankton ranged from 12 to 109 ng (g dw)-1 without clear trends between geographic locations or between fjords and coastal areas. Also, the concentrations did not vary between the different plankton size fractions. MeHg concentrations were lower in the mesozooplankton faecal pellets than IHg, which may be due to the higher assimilation of MeHg than IHg in mesozooplankton tissue. Our results confirm that Arctic zooplankton assimilates MeHg more efficiently than IHg and may contribute significantly to the partitioning and cycling of different Hg types in Arctic marine ecosystems.

Zooplankton abundance and biovolume size-spectra in the western tropical Atlantic - From the shelf towards complex oceanic current systems.

Mesozooplankton plays a pivotal role within marine food webs. However, there is a paucity of studies examining the size-spectra and trophic efficiency of these communities in tropical neritic and oceanic waters. Here, normalised biovolume (NBSS) and normalised numbers size-spectra (NNSS) were fitted on zooplankton data from the southwestern tropical Atlantic. The spectra were compared to assess the trophic efficiency slope (NBSS) across different regions, the Shelf, the western boundary current system (WBCS), and the South equatorial current system (SECS) off oceanic islands. Zooplankton was collected from September to October 2015, at 34 stations using oblique hauls with a 300μm mesh bongo net from 200m depth to the surface during either day or night. Samples were analysed using a ZooScan. A total of 30 zooplankton taxa were recorded. Mean abundance and biovolume were 62.6 ind m-3 and 36.2mm³ m-3, respectively. Zooplankton community structure differed significantly between areas, in abundance and biovolume. Copepoda was the most abundant group, representing 66% and 57% of the abundance in coastal areas and oceanic islands, respectively. Fish larvae, gelatinous plankton (mostly Chaetognatha, Thaliacea, and Siphonophora), and Decapoda were the main contributors in terms of biovolume. Overall, smaller organisms were found at the shelf, while larger organisms were found in the SECS. Total abundance was significantly higher on the shelf and in the WBCS than in the SECS, while individual biovolume was higher in the SECS. The NNSS and NBSS slopes were significantly steeper on the shelf than in the other areas. This can be attributed to the higher contribution of small copepods on the shelf and the higher contribution of large-sized copepods and other large organisms in oceanic waters. Flatter NBSS and NNSS slopes offshore reveal a higher trophic efficiency, illustrating the importance of large zooplankton, particularly chaetognaths and decapods, in contributing to the ecosystem secondary productivity in oligotrophic tropical pelagic marine ecosystems. The combination of both NNSS and NBSS provided a more comprehensive view of ecosystem structure and fluxes.

Dissolved organic carbon can alter coastal sediment phosphorus dynamic: Effects of different carbon forms and concentrations.

Coastal waters are receiving increasing loads of dissolved organic carbon (DOC), differing in structural complexity and molecular weights with potential different effects on the phosphorus (P) dynamics in these waters. This study conducted an in-situ investigation in Xiangshan Harbor, China, to explore the patterns of P release in response to DOC inputs. To further elucidate the underlying mechanisms behind the DOC-affected sediment P release, a two-month mesocosm experiment was undertaken with coastal sediment (Xiangshan Harbor) to which acetate, glucose, and humic acid (representing the fermentation product, the simple available carbon, and the refractory humic-like carbon sources, respectively) were separately added to the overlying water at dosages of 0, 5, 10, and 20mgC L-1. We found that: i) sediment P release showed a non-linear increase with DOC input, a pattern likely due to the diverse forms of DOC in coastal zones, which had varying impacts on P release; ⅱ) significant P release for labile DOC (acetate- and glucose-amended) treatments but retention for humic acid treatments, and the magnitude of P changes mainly depended on the amount of DOC addition; ⅲ) acetate and glucose shared similar P-release-promotion mechanisms, i.e., decreased dissolved oxygen, increased ppk genes in water, and increased P bacteria and alkaline phosphatase activity were the dominant factors behind the P release for both carbon sources, as indicated by piecewise structural equation modelling; ⅳ) humic acid-inhibitory effects on sediment P release, which likely reflect increasing "P-humic acid" complexes that favor P adsorption and sedimentation and form stable "humic acid-enzyme" complexes that reduce the catalytic activity of alkaline phosphatase. Our findings provide new understanding of relationships between loading of DOC with different form/concentration and sediment P dynamics in coastal areas.

Sedimentary dynamic processes affected by tropical cyclones and anthropogenic forcing in a small-scale estuary: The Sheyang River Estuary, China

Amid the robust landward migration of tropical cyclones (TCs) in the context of global warming, the sedimentary dynamic processes in coastal areas are increasingly affected by TCs. Concurrently, coastal environments face tremendous stress from anthropogenic interventions, such as land reclamation and jetty construction. However, most research puts more emphasis on TC impacts on large-scale estuaries or marginal seas, leaving the sediment dynamics in small estuaries, particularly under the influence of TCs and man-made structures, largely unexplored due to the limited field data. To address this issue, this study took the Sheyang River Estuary (SRE) as an example and explored the sediment dynamic responses to TCs and the jetty construction during Typhoon Lekima in August 2019, utilizing the Finite Volume Coastal Ocean Model (FVCOM). The results showed that the rotating wind field of Lekima induced rapid variations in wave height, residual water level, and currents at different typhoon stages and strengthened the sediment resuspension and alongshore transport. Furthermore, by comparing the effects of Lekima with Typhoon Chan-hom in July 2015, we found that TCs with different tracks produced markedly different dynamic processes, yet all facilitated sediment exchange between the northern and southern areas within the SRE. The study also highlighted the impact of jetty construction on sediment transport during typhoons, noting that jetties can disrupt the typhoon-induced alongshore sediment flux and create eddies on either side by altering sediment advection. In the navigational channel area, the construction of jetties can strengthen the along-channel estuarine circulation during typhoon events, potentially leading to severe channel siltation by trapping riverine sediments and inducing net landward sediment transport. While site-specific, this study provides valuable insights into the combined effects of extreme events and human interventions on sedimentary environments in small estuaries.

Utilizing the cloud-based satellite platform to explore the dynamics of coastal aquaculture ponds from 1986 to 2020 in Shandong Province, China.

Coastal pond aqua farming is critical in aquaculture and significantly contributes to the seafood supply. Meanwhile, the development of aquaculture ponds also threatens vulnerable wetland resources and coastal ecosystems. Accurate statistics regarding the distribution and variability of coastal pond aquaculture are crucial for balancing the sustainable development of coastal aquaculture and preserving the coastal environment and ecosystems. Satellite imagery offers a valuable tool for detecting spatial-temporal information related to these coastal ponds. Furthermore, integrating multiple remote sensing images to acquire comprehensive spatial information about the coastal ponds remains challenging. This study utilized a decision-tree classifier applied to Landsat data to detect the spatial distribution of coastal ponds in Shandong Province from 1986 to 2020, with data analyzed at five-year intervals, primarily based on the Google Earth Engine cloud platform. A pond map in 2020, extracted from Sentinel-2 imagery, was used as a reference map and combined with the results from Landsat data to explore the landscape changes of coastal ponds. The results indicated that Shandong Province's coastal pond area underwent significant expansion before 1990, followed by slower growth from 1990 to 2010 and eventual shrinkage after 2010. Specifically, the pond area expanded from 428.38km2 in 1986 to a peak of 2149.51km2 in 2010 before contracting to 2012.39km2 in 2020. The region near Bohai Bay emerged as the epicenter of Shandong's coastal aquaculture, encompassing 62% of the total pond area in 2020. The government policies previously promoted the expansion of coastal pond farming but shifted to curbing the uncontrolled development of aquaculture ponds.

Relationship between habitat characteristics and microalgae community on the coastal area of Malang Regency, Indonesia

Relationship between habitat characteristics and microalgae community on the coastal area of Malang Regency, Indonesia

Characterization of plastic ingestion in urban gull chicks and its implications for their use as pollution sentinels in coastal cities.

The increase of plastic pollution represents a significant ecological threat, particularly in human-impacted environments. However, the effects of plastic ingestion by urban wildlife are less understood. This study investigates the presence of microplastic (MPs; plastic <5mm in size) and macroplastics (MaPs, plastic >5mm in size) in yellow-legged gull (Larus michahellis) chicks inhabiting the urban marine ecosystem of Barcelona (northeastern Spain). The stomach contents of 56 gull chicks were analysed, revealing the presence of MPs in 100% of the individuals and MaPs in 19.64% of individuals. Additionally, trophic analysis, through stomach content and stable isotope determination, identified links between diet and plastic ingestion, with diet diversity associated with higher MaP abundance. These results highlight the high presence of plastics in the early stages of an urban-dwelling wildlife species and open the potential role of the use of urban gull chicks as sentinels of marine and terrestrial pollution in urban coastal areas. The findings suggest that chicks can serve as bioindicators of plastic pollution, emphasizing the urgent need to address the high levels of plastic contamination in urban environments.

Exploring Urban Coastal Areas: Investigating the Urban Coastal Areas as a Reservoirs of Antibiotic Resistance Genes★

Antibiotic resistance genes (ARGs) have long served as adaptive defensive mechanisms among bacteria, enabling their survival and propagation in challenging environments. The consequences of inefficient wastewater treatment have culminated the emergence of untreatable and lethal extensively drug-resistant. To understand the relationship between wastewater effluent and marine ecosystems, we conducted a study to monitor the diversity and prevalence of common ARGs in Hong Kong's urban coastal areas at different seasons.Our findings revealed that sul 1 was the most abundant resistance gene, with an average relative abundance of 4.45×10-2 per 16s rRNA gene copy. Moreover, temperature, dissolved oxygen, and salinity were key factors influencing seasonal variations in total ARGs abundance. The influence of environmental factors varied based on ARGs' association with Intl1, with Intl1-associated ARGs strongly correlating with temperature and dissolved oxygen. Notably, despite their abundance, sul1 and mphA exhibited similar correlations with both Intl1 and key environmental factors, suggesting these ARGs share a common dissemination mechanism. Moreover, the robust association between resistance genes and mobile genetic elements (MGE) could potentially act as a valuable indicator for assessing the efficacy of removing ARGs in wastewater treatment methods when operating under carefully optimized environmental parameters.

Hydrodynamic insights, environmental assessment, and fisheries study of the Kelantan coastal area: A comprehensive analysis

Hydrodynamic insights, environmental assessment, and fisheries study of the Kelantan coastal area: A comprehensive analysis

Niche and interspecific association of dominant zooplankton species near the Taishan coastal area in the South China Sea.

Marine zooplankton communities represent one of the most diverse and abundant species groups on earth. To investigate the ecological niche characteristics and interspecific interactions of marine zooplankton, and to elucidate their role in carbon deposition and biogeochemical cycling, we conducted a study on the zooplankton community near Taishan in the South China Sea between December 2015 and September 2016. Using niche breadth, niche overlap, the variance ratio method, chi-square tests, and linkage coefficients, we analyzed the interrelationships among the major zooplankton species. Over four sampling seasons, we identified 61 species of zooplankton spanning 11 taxonomic categories. Copepods were the most abundant, comprising 32 species and accounting for 66.67% of the total. The niche breadth and overlap of dominant species displayed seasonal variation, with niche breadth ranging from 2.04 to 2.82, and niche overlap between species pairs ranging from 0.31 to 0.85. Correlation and interspecies association analyses revealed that interspecies associations near the Taishan coastal area in autumn and winter were generally significantly positively correlated. However, the relationships among the 18 dominant species groups during these seasons were not statistically significant (p>0.05), indicating weak interspecies connectivity within the zooplankton communities in this region. Our findings also suggest that anthropogenic disturbances and seasonal variations influenced the zooplankton community, contributing to its structural instability.

Coastal vulnerability to extreme weather events: An integrated analysis of erosion, sediment movement, and land subsidence based on multi-temporal optical and SAR satellite data.

Coastal areas undergo continuous transformations, altering their geometry under the influence of external forces like tides, waves, and extreme events. Thus, monitoring the impact of extreme weather events on coastal regions is crucial to prevent potential cascading hazards. Here, we utilized time-series optical and SAR satellite data and tide records, coupled with sophisticated analytical techniques, to analyze erosion processes, sediment transport, and vertical land movement (VLM) at an embayed sandy beach (i.e., Haeundae Beach, South Korea). We found a significant erosion rate of -4.12m/year during typhoon periods, compared to non-typhoon periods (-3.61m/year). Between 2017 and 2023, 5.63ha of beach area and 14,428.9m3 of sediment were lost due to typhoon-induced sand movement, leading to coastline retreat and foreshore erosion. The PS-InSAR-derived localized VLM trends of fast-subsiding areas (-3.57mm/year), combined with a current sea-level rise (2.34mm/year), underscores the heightened vulnerability to future extreme weather events. The findings of this study provide insights into the erosional processes, land subsidence, and sediment transport due to extreme weather events, which can contribute to the development of erosion control technologies and engineering applications to prevent cascading hazards. The proposed integrated framework can be implemented in similar coastal environments to mitigate climate-change-induced coastal vulnerabilities.

Bacterial community composition and metabolic characteristics of three representative Marine areas in northern China

Bacteria are essential components of ecosystems, participating in nutrient cycling and biogeochemical processes, and playing a crucial role in maintaining the stability of marine ecosystems. However, the biogeographic distribution patterns of bacterial diversity and metabolic functions in the estuarine and coastal areas of northern China remain unclear. Here, we used metagenomic sequencing to investigate the bacterial community composition and metabolic functions in sediments from the adjacent waters of the Yellow River Estuary, the Yellow Sea Cold Water Mass, and the adjacent waters of the Yangtze River Estuary. Among the 9164 species that were found, the most dominant microbial communities are Pseudomonadota, Actinomycetota, Bacteroidota, and Bacillota, but there are significant differences in the species composition in these three typical habitats. Amino acid metabolism and carbohydrate metabolic pathways were highly enriched. Glycoside hydrolases (GHs) predominate in carbon metabolism across all samples. In nitrogen metabolic pathway, genes related to organic degradation and synthesis are more abundant in the Yellow River Estuary than the other two habitats. In sulfur metabolic pathway, genes involved in assimilatory sulfate reduction are significantly enriched. Assimilatory sulfate reduction might be crucial for sulfur metabolism in coastal regions, with a full assimilatory nitrate reduction pathway found in Desulfobacterota. This research offers insights into the compositional diversity, metabolic functions, and biogeographic distribution patterns of bacterial communities in sediments from typical marine areas of northern China.

Groundwater vulnerability and, risk assessment of seawater intrusion for the development of a strategy plan towards sustainability: Case of the Souss-Massa coastal area, Morocco

Groundwater vulnerability and, risk assessment of seawater intrusion for the development of a strategy plan towards sustainability: Case of the Souss-Massa coastal area, Morocco

Spatiotemporal distribution of chlorophyll-a concentration in the south China sea and its possible environmental regulation mechanisms.

In this paper, the spatial and temporal distribution of chlorophyll-a (Chl-a) concentration in the South China Sea (SCS) and its major environmental regulator mechanisms were studied by using satellite remote sensing data sea surface temperature (SST), sea surface wind (SSW), and aerosol optical depth (AOD) spanning from January 2000 to December 2022. The results show that Chl-a in the SCS exhibit notable spatio-temporal variations: they peak in winter (∼0.234mgm-3) and autumn (∼0.156mgm-3), and decline in spring (∼0.144mgm-3) and summer (∼0.136mgm-3). Spatially, Chl-a near the coast and in upwelling areas are generally higher than those in offshore areas. A monthly average time series correlation analysis across the entire SCS shows that Chl-a significantly correlate with SST (R=-0.78, P<0.01) and SSW (R=0.78, P<0.01), and moderately correlate with AOD (R=0.29, P<0.01). The regulator of environmental factors also shows seasonal differences: during the winter monsoon period, Chl-a has the highest partial correlation with SSW (R=0.73, P<0.01), followed by SST (R=-0.55, P<0.01), and no significant partial correlation with AOD (R=0.14, P>0.05); during the summer monsoon period, Chl-a has the highest partial correlation with SST (R=-0.63, P<0.01), followed by AOD (R=0.40, P<0.01), and no significant partial correlation with SSW (R=0.12, P>0.05). A comprehensive analysis indicates that the mixing and upwelling processes regulated by the winter monsoon and SST exert a greater influence on nutrient variations. The enhanced mixing caused by the winter monsoon and the cold environment promote the growth of phytoplankton, leading to higher Chl-a concentrations in winter compared to other seasons. In contrast, the increased temperature in the summer monsoon period significantly weakens the mixing effect of wind speed and nutrients influx from deep layers to surface layers. Consequently, the external nutrient sourced from aerosol becomes crucial in determining Chl-a distribution, especially in oligotrophic regions near the southern SCS and the basin. However, in regions where other nutrient sources significantly contribute, such as the coastal areas influenced by seasonal upwelling, the contribution of aerosols is negligible.

Factor associated with diarrhea incidence in coastal area Bungkutoko, Kendari, Indonesia

Diarrhea is a health problem that has not been resolved until now, even this disease is the main cause of death in toddlers both globally and nationally. Diarrhea cases in the Nambo Health Center work area, Kendari City have continued to increase over the past 3 years. Bungkutoko is one of the sub-districts located in the coastal area of ​​Nambo District, Kendari City. Coastal areas include areas with inadequate sanitation access, with problems including the availability of clean water, toilets and other basic sanitation facilities that can be factors causing diarrhea. This study aims to determine the factors related to the incidence of diarrhea in the coastal area of ​​Bungkutoko. An observational analytic with cross sectional design was conducted in this study. This study was carried out in June 2024 in Bungkutoko Village, Kendari City, Southeast Sulawesi Province. The sample consisted of 70 respondents obtained using non-probability sampling, accidental sampling techniques. Data were collected using questionnaires and observation sheets, then processed and analyzed using a computer program. Data were analyzed bivariately using chi square test and fisher exact (if not eligible for chi square test) with 95% confidence level (α = 0.05). The results showed there was a relationship between water treatment before drinking and the incidence of diarrhea (p-value = 0.03), and there was no relationship between hand washing behavior (p-value = 0.09) and the condition of waste disposal sites (p-value = 0.25) with the incidence of diarrhea in the coastal area of ​​Bungkutoko, Kendari City. Therefore, it is expected that the community can process drinking water before consuming it to avoid diarrhea.