Fish Production Research Articles

IDENTIFICATION OF Anisakis simplex IN PURPLE SPOTTED BIG EYE FISH (Priacanthus sp.) FROM SOUTH BALI WATER AREA

Anisakis simplex infection in fishery products can be dangerous because it has zoonotic can transmitted infection from fish to humans. Purple spotted big eye fish (Priacanthus sp.) is one of the reef fish species produced in the waters of South Bali and is not immune to the zoonotic threat Anisakis simplex poses. This study was conducted to identify Anisakis simplex which is known to infect Purple Spotted Big Eye Fish (Priacanthus sp.) in the South Bali Water Area. The parameters observed in this study were related to the prevalence and intensity of Anisakis simplex in Purple Spotted Big Eye Fish (Priacanthus sp.). The research method used was descriptive quantitative with purposive sampling of fish samples. The samples used were 30 fish obtained from 15-20% of the catch of purple spotted big eye fish in the South Bali Water Area. The results of the study showed that the morphological identification that had been carried out showed that Anisakis simplex found to infect Purple Spotted Big Eye Fish (Priacanthus sp.) was an Anisakis simplex type III larva with a prevalence rate of 26.3% classified as a frequent infection. The intensity value of Anisakis simplex in this study was 4.92 ind/fish and was classified as a low category. The predilection from this study showed that the most infections were in the intestinal organs.

The Effects of Fenobucarb on the Physiology, Behavior, and Growth of Silver Barb (Barbonymus gonionotus).

This study assessed the effects of fenobucarb (F) (1%, 10%, and 20% of the LC50-96h value) on the brain cholinesterase (AChE) activity, food intake (FI), feed conversion rate (FCR), and growth of silver barb (Barbonymus gonionotus, Bleeker, 1849). It also assessed the AChE inhibition levels that cause the abnormal swimming, behavior, and mortality of silver barb and how the feeding regime affects the recovery rate of the AChE activity. The results showed that the brain AChE inhibition increased with the F concentrations. It peaked after nine hours, at 73.6% and 79.7% for the two highest concentrations, and then the AChE activity started to recover. After 96 h, the inhibition level was still 11.8% in the fish exposed to the two lowest concentrations and 30.5% in the fish exposed to the highest concentrations. Even when placed in clean water, the inhibition level in the fish that were exposed to the highest concentrations and only fed every third day was 32% after 14 days. Although there were no differences in the feed intake at any time, the fish exposed to F had a higher FCR and a lower specific growth rate and weight compared to the control fish at the later stages of the experiment. Thus, although the use of F in rice farming in the Mekong Delta may not lead to direct fish kills, it impacts the growth and health of the fish, which could have negative implications for wild fish populations and the long-term production of healthy fish in the Mekong Delta.

ANALYSIS OF FINANCIAL OF FISHERY PRODUCT PROCESSING BUSINESS IN PRODUCTION HOUSE “IBU SITI RAHMAH” IN MUARA ADANG VILLAGE PASER REGENCY

This study aims to determine the profitability of the business and to determine the financial feasibility of fishery product processing business in the production house “Mrs. Siti Rahmah” with discounted investment criteria (NPV, IRR, and Net B/C) and non-discounted (Payback Period). This research was conducted in October 2023. The determination of respondents is guided by the sample method, with the selected respondents being fishery product processing businesses in the “Mrs. Siti Rahmah” production house. The analytical tools used in this research are cost analysis, revenue, profit, and also financial feasibility analysis with discounted and non-discounted investment criteria. The results showed that the fishery product processing business in the production house “Mrs. Siti Rahmah” in Muara Adang Village, Long Ikis Subdistrict, Paser Regency received Rp 44,880,000/year and earned a profit of Rp 9,775,782/year. From the financial aspect, the fishery product processing business is feasible to run and develop with an NPV value of Rp 50,081,700, IRR of 79%, Net B/C of 2.84 and PP of 1.19 years.

THE EFFECT OF ADDING BLUE SWIMMING CRAB SHELL FLOUR ON INCREASING CALCIUM AND THE PREFERENCE LEVEL FOR BISCUIT

Blue Swimming Crab (Portunus pelagicus) has a calcium content of 19.97% which can be fortified in biscuit products. The purpose of this study was to understand the impact of using crab shell flour in biscuits on panelist preferences. The study was conducted from July to August 2024 at the Fisheries Product Processing Laboratory, Faculty of Fisheries and Marine Sciences, Padjadjaran University. The method used in this study was experimental using Friedman data analysis consisting of 4 treatments and 20 replications in the form of semi-trained panelists on organoleptic parameters, namely appearance, aroma, taste, and texture and chemical parameters, namely calcium content, water content, ash content, protein content, fat content, and carbohydrate content. The results of the hedonic test proved that the addition of 5% crab shell flour was the most preferred treatment, with an average appearance value of 7.9; aroma 8.2; taste 8.1; and texture 8.1. Based on chemical analysis of the most preferred treatment, namely the addition of 5% crab shell flour produced a calcium content of 1.98%; water content 2.11%; ash content 3.45%; protein content 12.35%; fat content 9.91%; and carbohydrate content 72.18%.

Сверхкритические экстракты бурых водорослей в технологии рыбных пресервов

Natural preservatives make it possible to maintain the quality and safety of fish products, which makes this matter a relevant and promising research area. This article describes the effect of supercritical extracts of marine brown algae Undaria pinnatifida and Ascophyllum nodosum on the quality and safety of fish preserves from Pacific herring in oil and mayonnaise. The experimental samples contained 3% of supercritical extracts of brown algae in the fillings. The samples were stored at 0–5℃ for six months. The authors used standard research methods to study the microbiological, sensory, and physicochemical variables. The safety indicators were established by standard methods in the accredited test center of the Far Eastern Federal University. The acid number was determined by neutralizing free fatty acids with an alcohol solution of sodium hydroxide while the peroxide number was determined by the titrimetric method. The sensory profile included appearance, consistency, color, smell, taste, and the general state of the filling, which were assessed on a five-point scale. The supercritical extracts of brown algae affected the development of microorganisms in both kinds of preserves during storage. The QMAFAnM in the test samples approached that in the control during 6 months of storage, which indicated an opportunity to extend the shelf life of the experimental samples by two months. The experimental samples had lower peroxide and acid numbers, as well as better sensory indicators. In this research, supercritical extracts of U. pinnatifida and A. nodosum improved the quality and safety status of oil and mayonnaise herring preserves. The extracts reduced the accumulation of QMAFAnM and microscopic fungi while slowing down lipid oxidation and hydrolysis.

A preliminary study on the effect of the combination of Blaptica dubia (Order: Blattodea) and commercial fish feed on red hybrid tilapia, Oreochromis sp.

Fish meal and soybean meal are the main sources of protein in most fish feeds. Changes in feed and fish production costs are a concern for aquaculturists. Because they are a natural component of fish diets and have a high protein, vitamin, and digestibility profile, insects may be able to contribute to meeting the growing demand for fishmeal. This study was a preliminary investigation on the effect of various dietary combinations (Blaptica dubia + commercial pellet) on the weight of red hybrid tilapia, Oreochromis sp. fry. The Oreochromis sp. fingerlings were acclimatized to the laboratory condition for seven days. Five different mixtures of feed were concocted [T1 (60% B. dubia + 40% commercial pellet), T2 (70% B. dubia + 30% commercial pellet), T3 (80% B. dubia + 20% commercial pellet), T4 (90% B. dubia + 10% commercial pellet) and T5 (100% B. dubia)]. The control group of Oreochromis sp. was fed with 100% commercial pellet. Throughout the experiment period, the growth of the fish was monitored weekly for 15 weeks. Then, the fish were euthanatized, and the liver was subjected to histology analysis. The results show that T3, T4, and T5 feed mixtures promote the best growth and survival rate for Oreochromis sp. while causing liver damage. T1 and T2 fish feed ratios are better alternatives as they promote healthy fish and increased weight (p < 0.05).

The study of high-protein plant components on the example of soybeans and corn for aquaculture feed

It is important to use nutritious compound feeds with high content of protein in order to obtain qualitative marketable fish products under an intensive cultivation. During the production of high-protein aquaculture feeds, protein-rich animal and plant ingredients should be added to the composition. To such components refer: fish flour, meat-and-bone meal, wheat, corn, various types of soybeans, etc. Animal ingredients can be partially replaced by vegetable ingredients, but should not be 100%. Popular plant-based feed additives are soybean and corn. They are rich sources of plant protein which make them an ideal supplement to form a complete fish diet, especially in conditions of the intensive cultivation. These ingredients are often cheaper in comparison to animal proteins, which is the reason why the use of these ingredients makes feed more affordable for fish producers. For producers, semi-finished products of two or more ingredients are produced now as pellets or dry mixes. It is made to simplify the production process. In the majority of cases, these additives include a combination of animal protein and plant protein. This paper considers plant components such as soybean and corn in combination with fish flour for the manufacture of compound feeds. It also presents amino acid compositions of these components. Studies on the determination of the amount of proteins, fats and carbohydrates in experimental feeds containing soybean and corn are conducted and described. In the course of the experiment it is revealed that the feed with soybean content has a higher percentage of crude protein content, but the feed with corn has a higher content of carbohydrates in its composition.

Pathological studies on skeletal muscle atrophy in common fish products from El-Jubail Province, Saudi Arabia.

In this study, 10 fish species, Jayan flounder (Pseudorhombus javanicus); Oriental sole (Eurgglossa arientalis); Oange-spotted grouper (Epinephelus coioides); Blacktip trevally (Caranx heberi); Towbar seabream (Acanthopagrus bifascia); Smalltooth emperor (Lethrinus microdon); Spangled emperio (Lethrinus nebulous); Sharptooth hammer croaker (Johnius vogleri); Bigeye croaker (Pennahia anea) and Redspine thread bream (Nemipterus nemurus), were examined in El-Jubail province, Saudi Arabia, Arabian Gulf region over three years from 2017 to 2020. The examined fish species showed muscular atrophy in a total percent of 1.1%, but with variable percentages of affections in each species. The highest incidence (2.06%) was oberved in Spangled emperior (Lethrinus nebulous) while the lowest incidence (0.40%) was in Orange spotted grouper (Epinephelus coioides) and Smalltooth emperor (Lethrinus microdon). The affected fishes appeared with sunken eyes, severe emaciation, and prominent loss of skeletal muscle mass. During dissection, the muscular tissue in some examined species was rough while in others, it was edematous and gelatinous, and the internal organs of all fishes were atrophied. For routine histopathological examination, the tissue samples were fixed in 10% buffered neutral formalin. The examined tissue sections of the affected muscles showed variable degrees of histopathological changes depending on the species. Vacuolation of muscle fibers, Zenker's necrosis and myophagia were common in some species, while melanophores aggregation, edema, and hemorrhages were the most commonly observed changes in others. This study focused on the impact of this myodegenerative disease on the marketability of these edible fish species. Further investigation is needed to understand the impact of genetic predisposition, environmental pollution and other etiological agents on the occurrence of this phenomenon in this location.

Trends in Indonesia's Fishery Commodity Exports

Indonesia is one of the largest seafood producing countries in the world, with significant fisheries potential to support national economic growth. This study aim to analyzes the export volume and value trends of Indonesia's fishery products from 2018 to 2023, focusing on key commodities such as shrimp, tuna, seaweed, crabs, and lobster. The data used includes annual export volume and value for each commodity. The analysis results show that the volume of Indonesia's fishery exports fluctuated, with a significant increase until 2020 (1,262,830 tons) and a decline in 2021 and 2022, although it remained stable in 2023 (1,221,196 tons). The export value also showed a significant increasing trend, peaking in 2022 at 6,242,085 USD, before decreasing to 5,630,947 USD in 2023. Despite the decline in the last two years, the fishery sector in Indonesia continues to make a significant contribution to the national economy, with key commodities maintaining high competitiveness in the international market. These findings are important for the development of strategies that can boost Indonesia's fishery exports and strengthen its position as a leading global exporter.

Pemanfaatan IoT untuk Monitoring Kualitas Air dan Pelatihan Pembuatan Abon Ikan di Pokdakan Mina Jaya Banyumas

The Mina Jaya fish farming group in Banyumas Regency faces significant challenges in freshwater fish farming, primarily due to poor water quality caused by household waste contamination. This issue leads to high fish mortality rates, especially for mujaer, catfish, and tilapia, significantly reducing harvest yields and economic returns. To address these problems, this community service program introduced Internet of Things (IoT) technology for real-time water quality monitoring. The program also included training on IoT usage and post-harvest management, specifically the production of fish floss (abon), to enhance the value of fish products. IoT implementation proved effective in reducing fish mortality, improving water conditions, and increasing operational efficiency. Furthermore, the post-harvest training enabled the group to diversify their products and increase income. These results demonstrate the potential of combining modern technology and community empowerment to overcome aquaculture challenges and improve productivity. The program recommends expanding IoT usage, continuing post-harvest product diversification, and fostering sustainable collaboration to maximize long-term benefits.

The Evolution of Dietary Consumption in the Spanish Adult Population and Its Relationship with Environmental Sustainability.

The relationship between food consumption and environmental sustainability is becoming increasingly evident. The aim of this study was to estimate the evolution of the environmental impact of food consumption in the Spanish population, assessed in terms of greenhouse gas (GHG) emissions. Data collected from the Household Budget Survey were included, from approximately 24,000 households for the period of 2006-2023. The environmental impact of diet, in terms of GHG emissions, was estimated from the EAT-Lancet Commission tables, and the adherence to the Mediterranean Diet (MedDiet) was calculated using the Dietary Score index. The environmental impact of the Spanish diet, in terms of GHG, followed a downward trend over the years analysed, from 3978.1 g CO2-eq in 2006 to 3281.4 g CO2-eq in 2023, a decrease of 17.5%. The food groups with the largest decrease in consumption during this period were red meat (from 39.9 kg/year to 35.5 kg/year), fish (from 24.3 kg/year to 19.0 kg/year), and dairy products (from 113.4 kg/year to 99.7 kg/year). The level of adherence to the MedDiet increased slightly from 34 points in 2006 to 35 points in 2023 due to an increase in the amount of vegetables (42.7 kg/year vs. 44.3 kg/year) and grains consumed (53.1 kg/year vs. 72.6 kg/year) and a decrease in fish consumption (24.3 kg/year vs. 19.0 kg/year). In Spain, a reduction in GHG emissions associated with food consumption was observed due to a decrease in the consumption of red meat, fish, dairy products, and fats. National surveys are very useful tools to analyse the impact of food consumption on climate change and to assess the effect of the policies implemented to contain it.

Plankton Community Structure in the Estuaries of Banten Bay, Banten Province, Indonesia

Estuaries in Banten Bay support fisheries activities by serving as critical habitats for plankton communities, which form the foundation of the aquatic food web. This study aims to determine the structure of plankton communities, both phytoplankton and zooplankton, as baseline data for fisheries management in Banten Bay estuaries. Fieldwork was conducted in April and October 2021 at four estuaries in Banten Province: Karangantu, Wadas, Cengkok Estuary, and Pamong. Water samples were collected for plankton identification and analysis of physical and chemical water quality parameters in situ and laboratory. Key structural attributes, including Shannon - Wiener diversity index (H'), evenness index (E), dominance index (C), trophic status and canonical correspondence analysis (CCA), were also assessed. The highest abundance of phytoplankton was found in the Karangantu estuary, while the highest abundance of zooplankton was observed in the Pamong estuary, with overall abundance higher in April. Phytoplankton diversity was highest in Karangantu in October, whereas zooplankton diversity peaked in April. Plankton diversity indicated slight to moderate pollution levels, and trophic status analysis revealed eutrophic to hypertrophic conditions across the estuaries, suggesting high nutrient levels that support fish productivity. CCA revealed significant correlations between environmental variables and plankton composition and abundance. Mitigation strategies are recommended to monitor the growth of Chaetoceros sp. and Bacteriastrum sp., especially during the dry season. Long-term monitoring of water quality and plankton dynamics is essential in other estuaries of Banten Bay to assess nutrient loading impacts and develop strategies to mitigate harmful algal blooms. These efforts are critical to ensuring sustainable fisheries management in the region.

ECOSYSTEM INDICATORS TO ASSESS THE SUSTAINABILITY OF MULTISPECIFIC ARTISANAL FISHERIES IN FACE OF ENVIRONMENTAL CHANGES IN THE AMAZON BASIN SOUTH

The construction of hydroelectric dams causes several impacts on the aquatic environment and affects its structure and functions with direct consequences for the provision of ecosystem services. Despite its importance, since 1970, fisheries in the Amazon region, especially small-scale artisanal fisheries practiced by traditional populations, have been facing serious problems arising from human and climatic actions. In this study, we evaluated the impacts of dam construction and the environmental responses on fisheries production and fishing sustainability indexes in the Madeira River, which is the largest tributary of the Amazon River, between 2000 and 2019. Fisheries landing data in the city of Porto Velho and large-scale environmental variables were collected for each of the years in the period and were compared using general linear models. We found that dams, as well as changes in hydrological levels, affect fisheries production. The sustainability indexes showed a decline after the completion of the two dams. Moreover, catch-per-unit-of-effort showed a significant decline after the implementation of the dam. We therefore highlight the importance of understanding the factors that affect the sustainability of fisheries in large rivers in order to mitigate the impacts of large dams and other anthropogenic actions.

A case study on the effect of aquaculture operations on the physiology and behaviour of Atlantic salmon (Salmo salar) during two heat events on a commercial farm

Aquaculture farms represent a complex 3D environment and face regular seasonal challenges such as acute and chronically elevated temperatures during summer. Further, fish are exposed to the interaction between their environment and farm operations, which can cause challenging conditions. In the context of modern net-pen aquaculture and ocean warming, there is therefore a need to understand the welfare of these commercially important species under the realistic conditions they encounter. Fish were tagged with two types of biologgers measuring temperature, heart rate, external acceleration, and depth of fish as they experienced standard aquaculture operations over two periods of thermal stress, one short-term and one long-term. The fish response during the thermal stress events was compared with the periods preceding and following both events, and an additional analysis was carried out to further explore the effects of feeding and farm operations. Fish displayed signs of both secondary and potentially tertiary stress in response to the short- and long-term heat event and both heart rate and acceleration increased in response to feeding but displayed a more nuanced response to operations. As part of the broader concept of precision fish farming, this research, based on data from 7 individual fish, represents a case study that presents the potential use of biologgers as tools for recognising early signs of stress by observing the secondary stress response, thereby demonstrating the potential for informed and timely stress identification to guide farm management decisions to enhance fish welfare and production efficiency in commercial aquaculture.

PENDAMPINGAN AKSELERASI ADOPSI DIGITAL PLATFORM PADA UMKM BIDANG PEMASARAN PERIKANAN

In contrast to the 1998 crisis where MSMEs did not experience any shocks, MSMEs during the Covid pandemic experienced very strong shocks. However, MSMEs managed to recover quickly, especially those that integrated their marketing into digital platforms. As part of efforts to accelerate the digitalization of MSMEs, Mulawarman University through the Kedaireka program provides assistance to MSMEs in Samarinda where one of the targets is home culinary MSMEs. Assistance aims to 1) increase product promotion through business branding, 2) develop products, and 3) register MSMEs on digital platforms. Mentoring methods are carried out personally and collectively. Collectively, MSME players were given training regarding product promotion via digital platforms by resource persons from the Kedaireka Program management. Collective mentoring is followed up with a personal approach by students participating in the Kedaireka program. Personal assistance is carried out face to face by visiting MSME actors for around one month. The results of the assistance show that the obstacle faced by MSME actors in carrying out product development is the availability of raw materials where fishery raw materials are seasonal. Product promotion efforts carried out through product branding which was carried out by re-creating the business logo were successfully carried out without significant obstacles. Meanwhile, increasing marketing through digital platforms has not been successful due to the limitations of MSME actors in understanding the features and steps for updating product images as well as limitations in producing quality product images or photos. Efforts to accelerate the integration of marketing of fishery products require two conditions, namely product and promotion. In the product aspect, guaranteed availability of fishery products is very necessary for marketing sustainability and customer satisfaction. Meanwhile, in the promotional aspect, the quality of the images uploaded to the digital platform must be eye catching.

Hatay’ın Su ürünleri ihracatını canlandırma yolunda zorluklar: Karşılaştırmalı bir analiz (2008-2023)

A comparative analysis of seafood exports in the Hatay region between 2008 and 2023, in relation to overall trends in Türkiye and different regions, was conducted. Seafood export data was obtained from the Turkish Statistical Institute. The export amount has been in a long-term decline fishing and seafood production potential of Hatay, contrary to the general trend in Türkiye. Specifically, the export amount decreased by 62% since 2018, while it decreased by 22.65% in 2023 compared to the previous year. This ongoing downward trend can be attributed to the COVID-19, Syrian civil war, and the recent devastating earthquake in the region. Despite the high potential for seafood production in the region, investments have been limited due to the lack of allocation in organized industrial zones. Additionally, the absence of a wholesale fish market is a major issue preventing the emergence of a regional market. All these factors have caused disruptions in the supply chain and production, increased input costs, and market uncertainties both domestically and internationally. This indicates that infrastructure investments in the region must be prioritized by all stakeholders, the central authority, decisionmakers and policymakers for sustainable seafood exports contributing to regional development. In conclusion, despite the strong industrial and logistics infrastructure in Iskenderun Bay, the seafood sector in Hatay has failed to reach its full potential, unlike the national trend in Türkiye. This shortfall is directly reflected in export values. Therefore, necessary measures must be taken to effectively utilize the region's seafood potential.

Japon balığı üremesinin iyileştirilmesi: Kontrollü koşullar altında döllenme ve yumurtadan çıkma oranlarının optimize edilmesinde substratların rolü

Ornamental fish production is significantly impacted by whether fish spawn naturally under controlled conditions. Therefore, goldfish (Carassius auratus) were allowed to breed naturally using various types of substrates to investigate their effects on ovulation, fertilization, and hatching rates in an experimental setup. The goldfish were subjected to five different substrate treatments: T1 (water hyacinth), T2 (jute rope), T3 (polythene), T4 (net), and T5 (no substrate). The optimal pH and dissolved oxygen levels for goldfish spawning were found to be 7.14 to 7.24 and 5.65 to 6.22 mg/L, respectively. Results indicated that the highest number of eggs (356.66±40) was observed in the polythene substrate (T3), while no eggs were found in the absence of substrate (T5). The polythene substrate also yielded the highest fertilization rate (93%) and hatching rate (95.01%). Notably, goldfish exhibited no spawning behavior without any substrate, suggesting that substrate may act as both a spawning substrate and an essential cue for ovulation in goldfish. Furthermore, the study's findings support the recommendation of goldfish as substrate breeders. This research offers valuable insights for small-scale fish farmers, entrepreneurs, and hatchery owners looking to enhance goldfish spawning techniques in aquarium settings.

Currently important pathogenic Listeria species affecting animals and birds (review)

Listeriosis is one of the most severe gastrointestinal diseases in the world. Listeria affect different groups of animals and birds. The pathogen has been detected in meat, milk, fish and fish products. The disease shows spring and autumn seasonality. It has been reliably established that Listeria monocytogenes is ubiquitous in the environment. Listeria monocytogenes is a facultative intracellular pathogen. Infection with Listeria monocytogenes causes an invasive disease in animals and humans, which is transmitted via the fecal-oral route from an animal to a human, from a mother to a fetus. The pathogenesis of Listeria infection has been well studied. The gastrointestinal tract is the site of the pathogenic Listeria species transit and spread. The infection incubation period is 20–30 days in animals and humans. The clinical course in different animal species, including birds, has a number of specific features. Listeria can cross the intestinal, placental and blood-brain barriers. The manifestations of listeriosis include encephalitis, meningitis, gastritis, meningoencephalitis, mastitis, abortions, endometritis, etc. Pathogenic Listeria species show hemolytic activity which non-pathogenic species (except Listeria seeligeri) lack. The review presents the up-to-date information on the classification of Listeria, the pathogenicity factors of Listeria monocytogenes as the major pathogen, the mechanisms of Listeria infection development in different animal species.

ANÁLISE DA PISCICULTURA, APORTE DE NUTRIENTES E PRODUÇÃO DA MICROBACIA HIDROGRÁFICA DO RIO OCOY

Geotechnologies have become an essential tool for determining the sustainable development potential of aquaculture. The objective of this work was to map the physical and natural resources of the Ocoy River watershed. The mapping of the excavated ponds was carried out to estimate the discharge of Nitrogen and Phosphorus due to the fish farming activities of the microbasin. The methodology adopted was the qualitative and quantitative exploratory research for fish production and the use of open access geotechnology tools, such as QGIS and google Earth for mapping physical and natural resources. The methodology employed by Coldebella et al (2020) was used to estimate the nutrient input of fish farming in the watershed. characteristics are considered suitable for the development and expansion of fish farming in excavated ponds. The characteristics of the watershed are suitable for the expansion of aquaculture activity in the region, as it has a predominance of relief in hypsometric ranges of 200 to 300 meters, with gently undulating relief; the soil type Red Nitosol and morphometry that indicates that the watershed has a low risk of flooding and an elongated shape. Estimated ratios of Nitrogen and Phosphorus are low.

Seasonal Water-Column Structure Drives the Trophic Niche of Fish Communities on a Temperate Continental Shelf.

In seasonally stratified marine environments, the dynamics of benthic-pelagic coupling plays a crucial role in shaping food web structures and fisheries production. We examined fish food web structures across three distinct shelf areas in the Southern Sea of Korea (SSK) during both stratified (summer) and mixed (spring) water conditions using stable isotopes of carbon (δ13C) and nitrogen (δ15N). In spring, fish communities exhibited a broader range of δ13C values compared with summer, indicating more diverse feeding strategies. Seasonal variations in the proportion of benthic and pelagic prey in consumer diets highlighted shifts in benthic-pelagic coupling, illustrating how consumers adjust their reliance on benthic or pelagic resources. The relative importance of the benthic pathway varied among species groups throughout the year. During stratified conditions, reduced benthic-pelagic coupling led to increased reliance on benthic prey, particularly in the oligotrophic region influenced by the Tsushima Warm Current (TWC). The food web spanned five trophic levels, with a median of 3.6. Several species, notably benthic ones, declined in their trophic positions during the summer stratification. These results suggest that fish food webs in the SSK are shaped by temperature-driven seasonal bottom-up control. Our findings further offer insights into how increased water-column stratification could impact the trophic niches of shelf-food webs in the TWC region.