Biotic Index Research Articles

Baseline for marine cave monitoring strategies in the Alboran Sea using modified Cave Ecosystem-Based Quality Index (CavEBQI)

Marine caves constitute vulnerable habitats with unique and diverse biocoenoses. Monitoring these habitats is still challenging, which hinders the ability to evaluate global and local pressures that threatens their ecological value. In this study, ecological quality is estimated in twenty-one marine caves distributed along the northern and southern coasts of the Alboran Sea, a highly understudied area regarding marine caves. For that purpose, adjustments on the original Cave Ecosystem Based Quality Index (CavEBQI) are suggested in order to efficiently estimate the ecological quality of marine caves. Several methodological aspects regarding the assessment of biotic coverage, the visual census of motile fauna and the plasticity of the index usability were evaluated. Ecological quality of marine caves was in average “good” although it ranged between “poor”, “moderate” and “good” depending on the features of each cave. This study emphasizes the importance of adapting biotic indicators to biogeographical differences and technological advancements.

Validation of physicochemical water quality results through cross-checking with biological indices

ABSTRACT Biological assessment of rivers is critical for evaluating ecosystem health, detecting ecological changes, validating physicochemical monitoring data, assessing the effectiveness of water treatment systems, conserving biodiversity, and guiding water resource management. In this study, the surface water quality of the Karkheh River basin was evaluated using the National Sanitation Foundation Water Quality Index (NSFWQI) and the Iranian Surface Water Quality Index (IRWQIsc) for qualitative analysis. For biological monitoring, the Biological Monitoring Working Party (BMWP) index, along with the Average Score per Taxon (ASPT) and the Hilsenhoff Biotic Index (HFBI), was employed to provide a comprehensive assessment. Water quality was analyzed across 18 sampling stations, revealing significant spatial variation. Upstream areas exhibited relatively good conditions, with NSFWQI and IRWQIsc values of 59 and 68, respectively. In contrast, downstream locations near urban and agricultural areas demonstrated poor water quality, with values of 27 and 33, respectively. Overall, approximately 70% of the river's length has been severely impacted, highlighting the need for targeted planning and management to mitigate pollution. The biological indices corroborated the physicochemical results, revealing severe ecological stress in polluted regions. The close alignment between the NSFWQI and biological indicators emphasizes the importance of a multifaceted approach in assessing aquatic health. Key factors contributing to the river's degradation include excessive water extraction, untreated wastewater discharge, and diminished self-purification capacity, particularly in downstream areas.

Rapid assessment implementation in the development of biocriteria and organic enrichment evaluation in the Citarum River, Indonesia

ABSTRACT Socio-economic activities along the Citarum River basin in Indonesia can induce ecological disturbances in the structure of the benthic macroinvertebrate community. This research aims to (1) identify the environmental factors responsible (2) describe the ecological disturbances using biological measurements; (3) and to develop local biocriteria using a multi-metric conceptual approach. An inventory of benthic macroinvertebrates was carried out at eight stations over a sampling period of 3 months, along with water quality monitoring. The results confirm the change in the structure of benthic macroinvertebrate communities, explained by seven environmental parameters: dissolved oxygen (DO), ambient habitat quality, turbidity, nutrient enrichment, conductivity, temperature, and embeddedness percentage. The changes were then assessed using six biological measurements. Only four have been shown to be capable as alternatives to existing biocriteria. Their implementation enabled the development of local biocriteria compatible with the multimetric concept known as the cumulative biotic index (CBI).

Evaluation of the stock enhancement effect of Phascolosoma esculenta on macrobenthic communities using diversity and biotic indices in Yueqing Bay, East China Sea

Stock enhancement activities have many benefits but also negative impacts. The macrobenthic diversity index and the M-AMBI index were adopted to assess the effects of stock enhancement of Phascolosoma esculenta on macrobenthic communities and the local ecosystem in Yueqing Bay. The results revealed that the Shannon–Wiener diversity index (H’) and Margalef richness index (d) increased in October 2022 after stock enhancement, indicating a positive ecological restoration effect. The average M-AMBI in the intertidal zone of Yueqing Bay was 0.59, indicating good benthic ecological quality. Excluding seasonal factors, the M-AMBI in the intertidal zone increased after stock enhancement, indicating that stock enhancement by Phascolosoma esculenta had a certain positive effect on the intertidal ecological environment of Yueqing Bay. The increase in the M-AMBI occurred mainly in the low-tide zone, increased slightly in the mid-tide zone, and remained basically unchanged in the high-tide zone. On the one hand, Phascolosoma esculenta can accumulate heavy metals from the environment and release a large amount of organic matter throughout its lifecycle, promoting nutrient cycling, which plays a positive role in the environment. On the other hand, Phascolosoma esculenta is an economic species; however, the planting of mangroves in the low tide zone causes fishers to fish in the mid- and high-tide zones, so the changes in the M-AMBI values in each tidal zone are related mainly to Phascolosoma esculenta and anthropogenic disturbances.

Chemical composition of sediment and macrozoobenthos of small urban lakes, the Republic of Karelia, Russia

Assessing the benthic communities in water bodies under increasing anthropogenic pressure seems to be an urgent task of scientific research aimed at short-term and long-term monitoring of water bodies. This study focuses on the chemical composition of modern sediment and the current state of macrozoobenthos of small lakes in the Republic of Karelia (Kitaiskoe and Plotichie) influenced by anthropogenic factors. It was discovered that the lakes of Medvezhyegorsk have a higher concentration of heavy metals (such as lead (Pb), cadmium (Cd), molybdenum (Mo), and antimony (Sb),) compared to the Earth’s crust and natural background levels. The current study established the significant impact of industry and transportation on the movement and build up of pollutants in these lakes. The qualitative and quantitative parameters analysed for the benthic communities in the littoral and profundal zones included the species diversity, the structure of dominant species, and their percentage in the samples. According to the level of macrozoobenthos development, both reservoirs (lakes) were classified as mesotrophic, and according to the values of the chironomid index “K” as moderately polluted. The Pantle–Buck method (saprobic index) showed that the lakes can be classified as polluted (water quality class 4). Macrozoobenthos groups most tolerant to environmental conditions, for example, Chironomidae larvae, prevailed in the studied urban lakes. The economic development of the lakes leads to ecosystem transformation and long-term eutrophication over time affecting the biotic indicators of surface water quality. The results obtained can serve as a basis for complex environmental monitoring of the urbanized territories in the taiga zone.

DNA-based marine benthic assessment methods can perform as morphological ones, but an intercalibration is needed

There is an increasing need for legislation worldwide to monitor and assess the ecological status of marine ecosystems, due to increasing pressures from human activities. The costs and time of traditional analyses are high, while methods based on molecular analysis could reduce these costs and shorten evaluation times significantly. Some biotic indices used to assess the status need reference conditions to be applied. Hence, our objective here is to develop reference conditions for a molecular-based benthic index (M−gAMBI), which can be compared with a morphological one (M−AMBI). Using 6 years of data from estuaries and coasts, we have been able to set reference conditions for five water types, including richness, diversity and AMBI. However, one problem is the absence of the whole human pressure gradient in all water types, making difficult to validate the reference conditions. Based on the results of this research, the M−gAMBI index could be considered suitable for ecological status assessment since it meets most of the criteria for considering a genomics-based index suitable. However, it is considered necessary to advance in (i) improving the detection of errors in genomic methods and similarity with morphological methods, and (ii) an intercalibration exercise, allowing adjusting quality class boundaries and determining the ecological status in an equivalent manner using both methods.

WATER QUALITY ASSESSMENT OF THE SHUSHIC RIVER USING BENTHIC MACROINVERTEBRATES

The study of river waters and water flows of their tributaries is very important and necessary for the protection, use and improvement of their condition. According to the Water Framework Directive (WFD, 2000) the use of benthic macroinvertebrates in river water quality monitoring is considered an efficient method. This study was conducted during 2019 in the Shushicë river, where its purpose was to assess the quality of river waters using the biotic index ASPT (BMWP) and the biotic index - SWRC. The sampling method used was based on the Kick net technique with a mesh size of 500 microns. From the sampling taken in four stations, 481 individuals belonging to two types (Arthropoda and Annelida), one class (Insecta) and one subclass (N/K Oligochaeta) were collected. The unidentified species belong to 8 orders (Ephemeroptera, Plecoptera, Trichoptera, Diptera, Coleoptera, Haplotaxid, Odonata, Hoplonemertea) and 28 families. Based on the results obtained from the calculation of the ASPT (BMWP) biotic index, station I and III result in a "Clean" bio classification, station II and IV result in a "Partially clean" bio-classification. From the SWRC Biotic index calculations, the first station and the fourth station result in a bio classification of "Good", the second station results in a bio classification of "Clean", and the third station results in a bio classification of "Excellent" Based on the Biotic index ASPT (BMWP) and SWRC we can say that the Shushic river resultshas a good water quality, and partially with a slight organic pollution.

Ecological quality of the Jucusbamaba River, a high Andean urban river in northeastern Peru

The Jucusbamaba River, located in the northeastern region of Peru, flows through two towns that use its waters for agricultural activities. However, these activities generate waste discharged back into the river, which is additionally polluted by untreated domestic wastewater discharges. The main objective was to evaluate the ecological quality of this lotic system, analyzing biotic and abiotic parameters during two seasons. The biotic parameters included microinvertebrates and fecal coliforms, while the abiotic parameters encompassed temperature, pH, dissolved oxygen, electrical conductivity, turbidity, total dissolved solids, and biochemical oxygen demand. Six sampling points were established where physicochemical and microbiological parameters were analyzed. Simultaneously, quantitative sampling of macroinvertebrates was carried out at the same points to evaluate their diversity using Shannon- Wiener, Margalef and Simpson indices. The Andean Biotic Index (ABI) and the Biotic Family Index (FBI) were calculated to determine the ecological quality of the river using macroinvertebrates. Finally, the spatio-temporal variation of macroinvertebrate composition and physicochemical and microbiological parameters were analyzed. Very high concentrations of BOD, total dissolved solids, and electrical conductivity were obtained in the dry season, while in the rainy season, they were pH, dissolved oxygen, and turbidity. 12548 individuals from 6 classes, 11 orders, and 26 families were collected. The greatest richness of macroinvertebrate families was found at points 1 and 2, with Trichoptera, Ephemeroptera and Plecoptera individuals predominating. There was evidence of temporal variation in physicochemical and microbiological parameters, as well as in macroinvertebrate composition. It was concluded that the ecological quality of the Jucusbamba River decreases as it follows its course due to anthropic disturbances. This research can be used to develop management plans, awareness-raising, and sanitation measures to ensure the protection and conservation of the Jucusbamaba River.

Comparing the environmental impacts of pollution from two types of industrial zones on the coast

IntroductionThe construction of coastal industrial zones has significantly impacted the marine environment, with the extent of these effects varying based on the type of industrial activity. This study compares the environmental impact of two prevalent types of industrial zones along South Korea’s coast: ironworks and shipyards.MethodsWe assessed heavy metal pollution near these industrial zones using the Pollution Load Index (PLI) and Nemerow Pollution Index (Pn). To evaluate the impact of heavy metals and organic matter on macrobenthic communities, we employed redundancy analysis (RDA) and Spearman correlation analysis. Additionally, we used the AZTI’s Marine Biotic Index (AMBI), Multivariate AMBI (M-AMBI), and Benthic Pollution Index (BPI) to gauge the ecological quality of the affected marine environments.Results and discussionOur findings indicated that the biodiversity and abundance of species near shipyards were significantly lower than those near ironworks. Results of PLI and Pn revealed that the ecological risk posed by heavy metals from shipyard activities was significantly higher than from ironworks. The AZTI’s Marine Biotic Index (AMBI), Multivariate AMBI (M-AMBI), and Benthic Pollution Index (BPI) demonstrated that the ecological quality of Asan Bay (ironworks) is better than that of Dangdong Bay (shipyard). RDA analysis identified Lumbrineris longifolia, Ancistrosyllis hanaokai, and Theora fragilis as biological indicators for assessing heavy metal and organic matter pollution. Spearman correlation analysis indicated that BPI and species richness index are effective indicators for evaluating such pollution. Overall, the negative impact of shipyards on the marine environment was significantly more significant than that of ironworks. Our study provides valuable insights for the South Korean government in managing coastal industrial zones and formulating relevant policies.

Biotic indices freshwater ecosystems using aquatic entomofauna as a bioindicator

Biotic indices freshwater ecosystems using aquatic entomofauna as a bioindicator

Using a new fish indicator-based index with scoring and evaluation criteria to assess the ecological status in a disturbed subtropical river of China

Rivers are constantly disturbed by anthropogenic stressors. Developing robust biotic indicators to assess river environments across large spatial scales is important. In the subtropical Liuxi River of China, 34 native fish indicators, including 4 genera and 30 species, were selected from 108 fish species by linear discriminant analysis. These indicators were grouped into 19 ecological items and assigned evaluation scores according to the roles they played in the food web (e.g., keystoneness and trophic level) and their positive feedback on the environment (e.g., requirements for feeding, spawning/nursing, and migrating). Three formulae for calculating the index of fish indicators (IFI) were developed based on the scoring of each indicator and weighted by relative abundance (individual number, i.e., IFIN) and relative biomass (wet weight, i.e., IFIB). Spearman correlation analysis showed that IFIB, which had positive (P< 0.05) correlations with elevation (m), dissolved oxygen (mg/L), flow velocity (cm/s), Shannon-Wiener diversity, benthic index of biotic integrity, exhibited a more powerful explanation of biodiversity and environmental factors than IFIN and unweighted IFI. Therefore, IFIB was most suitable for constructing a scoring system to evaluate ecological status (e.g., water and habitat quality). These results suggested that fish indicator-based scoring and evaluation system was effectively in not only assessing the site- or region-specific ecological status bot also reflecting the fluvial biodiversity and food web integrity. Further application and promotion of this indicator-based evaluation method may improve field investigation efficiency and contribute greatly to the conservation and management of river ecosystems.

Assessing Methods to Monitor Aquatic Invertebrates in a Large River: Comparing Rock Baskets and Hess Samplers in the Snake River, Wyoming, USA

Large rivers are difficult to sample due to their size yet critical to monitor because humans heavily rely upon and alter them. Aquatic invertebrates are commonly used to assess the ecosystem quality of streams, but methods to sample large rivers are underdeveloped. We sampled aquatic invertebrates using a Hess sampler and rock baskets in the Snake River near Jackson, Wyoming, USA. Hess samples collected more aquatic invertebrate taxa and a higher proportion of Ephemeroptera, Plecoptera, and burrowing taxa. Rock baskets collected a higher proportion of Trichoptera, filterers, and clinging taxa. Bioassessment metrics differed between sampling methods; richness, diversity, evenness, Ephemeroptera, Plecoptera, and Trichoptera (EPT), and Hilsenhoff’s biotic index produced higher values in Hess samples, and percent EPT was higher in rock baskets. Non-metric multidimensional scaling and analysis of similarity indicated that the samplers collected different assemblages (p < 0.001). The standard error of total invertebrate density was smaller and most taxa were collected with seven replicate samples. Understanding how sampling methods alter the aquatic invertebrates collected will help managers develop monitoring protocols that are best suited to the river and collect the most unbiased invertebrate assemblages.

Developing Macroinvertebrate Biotic Indices in Nigerian Urban-Agricultural River Catchments: Is the Continuous Scoring System More Effective than Discrete Scoring System?

Developing Macroinvertebrate Biotic Indices in Nigerian Urban-Agricultural River Catchments: Is the Continuous Scoring System More Effective than Discrete Scoring System?

Biophysics indicators as the sustainable strategy for river pollution control (case study in Jangkok River, Mataram City, West Nusa Tenggara)

Background: Sungai Jangkok is one of those considered heavily polluted in NTB. The Biochemical Oxygen Demand (BOD) value has exceeded the standard for Class II water quality, and according to the Family Biotic Index (FBI) value, the river falls under the category of heavy organic pollution. The research objective is to realize sustainable management of the Jangkok Watershed in accordance with its river functions by implementing pollution control strategies. Methods: Data collection was conducted using questionnaires and interviews with the public and stakeholders (government and NGOs). Water quality data was obtained from DLHK NTB and DLH Mataram City, and sampling was carried out using the composite sample technique. The methods employed were STORET, QUAL2Kw, logistic regression, and SWOT. Findings: The research findings indicate that, in general, the Jangkok River in Mataram City falls into the heavily polluted category from 2015 to 2022, with an average STORET score of -79.25. Moreover, the pollution loads of BOD, COD, and TSS entering the river have exceeded the pollution carrying capacity. The condition is influenced by several factors, including the less favorable perception of pollution status (67%) and the usefulness of the river (59%) by the community. Additionally, the persistent behavior of littering and/or defecating in the river (23%), inadequate preventive practices (59%), insufficient wastewater disposal facilities (40%), and improper waste management (58%) are contributing factors. Moreover, the existence of houses backing up to the river (59%) also plays a role in the current condition. Some of the causes are the lack of synergy across administrative regions between stakeholders, the absence of law enforcement for the community, dependency on government budget for work programs, and the lack of incentives. Conclusion: The conclusion of this research suggests that the most effective strategy for taking is to develop a program for reducing pollutant loads that is integrated across districts and cities, integrated across agencies with various levels of authority, integrated with the community, and in accordance with the river's actual conditions and the socioeconomic community. Novelty/Originality of this Study: This study provides a novel approach by integrating quantitative water quality modeling (QUAL2Kw) with community behavior analysis to develop a sustainable and comprehensive strategy for controlling river pollution in the Jangkok watershed, Mataram City.

Using macrobenthic community structure and biotic indices to assess the ecological status of Wulan Estuary, Demak, Indonesia

Abstract. Hartati R, Widianingsih W, Zainuri M, Wardianto Y. 2024. Using macrobenthic community structure and biotic indices to assess the ecological status of Wulan Estuary, Demak, Indonesia. Biodiversitas 25: 3073-3087. Estuaries provide critical habitats for species, and they are valued commercially, recreationally, and culturally. They also filter for sediments and pollutants from rivers before entering the ocean, providing cleaner waters for marine biota. This study presents a unique approach to assessing the ecological status of an estuary using microbenthic community structure and biotic indices with a case study of Wulan Estuary, Demak District, Central Java Province, Indonesia. AZTI’s Marine Biotic Index (AMBI) community structure and biotic indices were used to assess ecological quality at eleven stations and determine the marine macrobenthic fauna's sensitivity to disturbances in two periods, i.e. August 2021 and 2022. A distinct spatial and temporal variation was evident in the macrobenthic community structure, where higher species richness and density were observed in 2022, with some species being more dominant in 2022. The trophic structure analysis showed the dominance of deposit-feeding bivalves in the fine sediments during those sampling intervals. These trophic groups, however, were dispersed less uniformly in the sandy substratum. Compared to the previous year, the density of herbivorous grazers and suspension feeders was higher in 2022. It is also shown by AMBI values that Wulan Estuary belonged to the good (slightly disturbed) to the high (undisturbed) condition, along with other biotic indices, which showed an enhanced habitat quality for benthic organisms. This result revealed the comparative ecological quality of related estuary ecosystems in Indonesia.

Macroinvertebrates as a Bioindicator of Water Quality in the Jangkok River, Lombok Island

Rivers are water bodies in open ecosystems where activities in the environment have an impact on river water quality. Monitoring of water quality is necessary to preserve aquatic resources. One of the river basins on Lombok Island is the Jangkok River. This river has a high utility, so water quality monitoring is needed. Macroinvertebrates are one of the best biological indicators for water quality monitoring. The objective of this study is to determine the diversity of macroinvertebrates and the quality of Jangkok River waters by using macroinvertebrates as bioindicators so that the results of this study can be used as a reference basis for the future use of Jangkok River water in the allocation of community needs. The method used in this research is biomonitoring with macroinvertebrate bioindicators, and the technique used in sampling is purposive sampling. Sampling was conducted at three stations, namely the upstream, middle, and downstream parts of the Jangkok River. The data analysis used was the Family Biotic Index (FBI) supported by physical-chemical parameters. The results of this study showed that the macroinvertebrates identified were 721 individuals consisting of 5 classes, 17 orders, and 36 families. The water quality of the Jangkok River, based on the FBI value in the upstream and middle sections, is still included in the good category, while in the downstream section, it falls into the very bad category.

Assessment of the ecological status of the river water system in European North under conditions of ultra-fresh humus waters using biotic indices (Suna River, Lake Onega Basin, Russia).

Protecting rivers and lakes from pollution is crucial for maintaining the health of aquatic ecosystems and ensuring the well-being of both wildlife and humans. Present study intends to examine the water quality of the Suna River (Eastern Fennoscandia in the European North of Russia) to assess the ecological risk. Widespread methods for assessing water quality based on macrozoobenthos and phytoperiphoton were applied. It was found that in conditions of ultra-fresh waters with high humus content, biotic indicators may indicate pollution of water bodies that do not actually experience significant anthropogenic impact. Ratings ranging from 'poor' to 'excellent' were obtained for different stations, reflecting the influence of natural features of different sections of the river. 'Good' water quality was noted at the river stones biotopes. In river gravel, sand and silt biotopes, as well as all lake biotopes, 'mediocre' water quality was found. The low anthropogenic income on the river catchment allows us to conclude that most indices for assessing water quality significantly underestimate the results in the natural conditions of Eastern Fennoscandia. Biotic indices EPT, BBI and EBI are most accurate for assessing the water quality of rivers and lakes in Eastern Fennoscandia.

Nematode Communities in Soils of the Same Volcanic Origin across a Gradient of Naturalization: From Intensive Agriculture to Forest

Nematodes play a key role in ecological environments. Biotic indices based on soil nematode community are effectively used for assessing soil health status. This work represents the opportunity to investigate three different management practices continuously maintained for 40 or more decades on soils with the same geological origin. This unique feature allows us to reduce variables and link biotic with abiotic factors. Therefore, the nematode communities of three neighboring volcanic soils under different managements were examined. The maximum values in soil biodiversity were found in the forest environment in which all the trophic groups were detected and well balanced. Instead, in permanent grassing and carnation crop greenhouse (CG), biodiversity indices progressively decreased with the intensification of agricultural practices. Furthermore, CG showed a stronger dominance of a specific plant-parasitic nematode identified as Heterodera daverti. Nematode indicators demonstrated that changes in the nematode community gradually varied from anthropic to natural environments whereas soil properties were feebly correlated to nematode community indicators. In conclusion, we demonstrated that biodiversity and ecological indices applied to the soil nematode community are effective at detecting alterations due to anthropogenic impact. Nematodes seem to be susceptible to perceiving the soil dynamics.

Evaluating the response of current biotic indices and functional metrics to natural and anthropogenic predictors in disconnected pools of temporary rivers

Temporary rivers, forming the majority of river networks worldwide, are key biodiversity hotspots. Despite their great value for maintaining biodiversity and ecosystem functioning, they are often neglected in biomonitoring programs due to several challenges, such as their variable hydromorphology and the difficulty of establishing reference conditions given their dynamic nature, resulting in highly variable communities. Disconnected pools often form in temporary rivers when flow ceases, providing refuge for aquatic taxa. Given their importance for biodiversity conservation, revising and adapting biotic indices are needed. Here, we evaluate the performance of current biological indices designed for perennial rivers (macroinvertebrates, diatoms) and functional metrics (macroinvertebrates) in assessing biological quality of disconnected pools. We sampled 55 disconnected pools in Catalonia, NE Spain, covering local (e.g., physico-chemical variables, water chemistry) and regional (e.g., human influence, hydrological variables at the water body level) natural and anthropogenic gradients. Only a few macroinvertebrate biotic indices (e.g., family richness, EPT/EPT + OCH and OCH) showed strong responses to anthropogenic predictors and were unaffected by natural predictors at both local and regional scales, making them suitable for biomonitoring. Of the newly adopted functional metrics of macroinvertebrate communities tested, only two (i.e., functional redundancy of predators and response diversity based on the total community) responded strongly to anthropogenic predictors. The rest showed varying responses to the interactive effect of anthropogenic and natural predictors, requiring calibration efforts. Models assessing these metrics explained <40 % of the total variation, likely due to the interplay of colonization/extinction dynamics and density-dependent trophic interactions governing community assemblages in disconnected pools. Although some existing biological metrics could potentially be used to monitor the ecological status of disconnected pools, we call for further development of biomonitoring tools specifically designed for these habitats since they will become more widespread with global change.

Can the Ecological Quality of Several Bays in South Korea Be Accurately Assessed Using Multiple Benthic Biotic Indices?

Bays are extensively impacted by human activities, and an accurate assessment of ecological quality is crucial for the environmental management and protection of bays. Most studies indicate that evaluating the ecological quality of bays using a single index presents challenges. In our study, we used five benthic biotic indices and a composite index to assess the ecological quality of three bays in South Korea. Our results revealed disparities in the ecological quality status assessment using five benthic biotic indices. The composite index performed better than the other benthic biotic indices in a principal coordinate analysis. Significant differences were observed between the values classifying stations as having an acceptable or unacceptable final ecological quality in terms of species indices (except for the Pielou’s evenness index) and the abundance of opportunist species (p &lt; 0.05). Consequently, we advocate for using a composite index to assess the ecological quality of the bays of the West Sea of South Korea. Furthermore, our study provides valuable information for marine ecological management and policy formulation in Korea and offers recommendations for using the composite index in future research.