The health status assessment of marine benthic ecosystems, as an important basis for maintaining the ecological balance of the oceans, relies on the long-term dynamic monitoring of benthic communities. In this study, we systematically reviewed the history and current applications of ecological assessment indices developed based on benthic organisms, including the perspectives of future fields in marine ecosystem health assessment. Traditional biological indices—including biodiversity indices (Shannon-Wiener index, Pielou index, etc.), functional group analyses (feeding evenness index), and indices (AMBI, M-AMBI, BENTIX index, etc.) based on the proportion of pollution-tolerant/sensitive species have advanced ecosystem health assessment by quantifying the responses of community structure to environmental stressors and facilitating the shift from qualitative to quantitative assessments. Nevertheless, traditional methods are limited by cumbersome procedures for morphological characterization, the limitations of single indicators, and regional differences in applicability. In recent years, environmental DNA (eDNA) technology has made up for the shortcomings of traditional methods by rapidly obtaining biodiversity information through high-throughput sequencing, and has derived novel indices such as gAMBI, which validates its complementarity with morphological methods. Integration of Artificial Intelligence (AI) techniques such as machine learning algorithms (Random Forests, Convolutional Neural Networks, and so on) with statistical analysis has improved the ability of ecosystem assessment models to resolve nonlinear relationships and multiple stressors. Meanwhile, automatic and intelligent image recognition technology offers the possibility of accurate and rapid identification of macrofauna and their monitoring. Future research shall integrate multidimensional data and interdisciplinary techniques to construct a more universal and dynamically responsive assessment system to cope with the potential impacts of global climate change and human activities on marine ecosystems.

Marine microorganisms, characterized by their immense biomass, rapid environmental response, and crucial ecological functions, serve as sensitive indicators for assessing the health of marine ecosystems. This article provides a systematic review of recent advances in marine ecological monitoring and health assessment based on microbial communities. First, we discussed the key characteristics of marine microorganisms as bioindicators, such as their high sensitivity to environmental stress and their functional redundancy in maintaining ecosystem processes. Case studies are presented to highlight the successful use of microbial monitoring to address climate change, pollution events, and ecological disasters. Next, we reviewed the evolution of marine microbial monitoring technologies, spanning from traditional cultivation methods to modern techniques such as high-throughput sequencing and Raman spectroscopy. We also compared the advantages and limitations of these approaches in practical applications. Finally, in response to challenges such as insufficient data standardization and the lack of quantitative assessment metrics, we proposed a systematic framework for future development. This framework emphasizes the need for end-to-end standardization from sampling to data analysis, the creation of intelligent diagnostic models that integrate multi-dimensional “Raman spectroscopy-genetic-environmental” information with the establishment of a national-scale specialized monitoring network. This review aims to provide theoretical supports and technical pathways for the development of a next-generation, high-resolution, real-time microbial-based marine ecological health assessment system.

The global ocean is currently facing a severe challenge of “cryptic ecosystem degradation”, characterized by subtle but progressive declines in ecosystem integrity. Conventional water quality monitoring often indicates regulatory “compliance”, while underlying processes such as food web disruption, loss of keystone species, and functional degradation of ecosystems continue largely undetected. This management paradox arises from traditional assessment paradigms that emphasize physicochemical conditions while overlooking biological structure and ecosystem functionality. This study proposes a target-driven framework for marine ecosystem health assessment, aiming to facilitate a paradigm shift in environmental management from “comprehensive census” approaches to “precision-based diagnostic” strategies. Departing from fixed indicator frameworks, the proposed system introduces a “three-level funnel” generation logic: (i) identification of core ecological issues based on specific management objectives, (ii) selection of key biological components and associated indicators, and (iii) design of an optimal spatiotemporal observation strategy. Guided by the principles of usability, effectiveness and adequacy, the framework is supported by an integrated “space-air-sea-intelligence” technological network and enables the transformation of observational data into actionable decision-making knowledge through an intelligent diagnostic engine. Case studies demonstrate that the framework can dynamically generate customized assessment schemes tailored to diverse management objectives, including “overall health assessment, ” “aquaculture carrying capacity evaluation”, and “disaster early warning”. Among these, the classical triad-based Index of Biotic Integrity (Z/F/B-IBI), encompassing “zooplankton-fish-benthos” represents the optimal scheme generated by the framework for achieving “regional-scale ecosystem health assessment”. Overall, the proposed system aims to maximize management efficiency while minimizing observational costs, thereby providing a dynamically adaptable, “precision medicine-like” solution for ecosystem-based marine management.

Dissolved oxygen (DO) is fundamental to maintaining the balance and stability of marine ecosystems. Under the combined influence of climate warming and intensified human activities, hypoxia in coastal waters worldwide is increasing in severity and spatial extent, making deoxygenation a major threat to coastal ecosystem health. As a typical semi-enclosed sea, the Bohai Sea is subject to multiple environmental pressures, including ocean warming, eutrophication, and rapid socio-economic development. In recent years, varying degrees of hypoxia have been reported across multiple subregions of the Bohai Sea, with hypoxic centers primarily located northeast of the Yellow River estuary and southeast of Qinhuangdao (occurring ≥3 times). This study reviews domestic and international research on hypoxia in the Bohai Sea, characterizes the spatial distribution patterns of summer hypoxia over the past two decades, and summarizes the dominant controlling processes. It further outlines the long-term development trends and their influencing factors in the Bohai Sea and proposes key directions for future research on hypoxia in the region. The study aims to provide a scientific basis and decision-making support for ecological health assessment and marine resource management in the region.

Health assessments of marine ecosystems rely heavily on the real-time diagnosis of biological status and functions. However, the “cognitive lag” of traditional biological observation (i.e., the long period from sample collection to species identification and data output, which makes it difficult to reflect rapid changes in the ecosystem promptly) has become the core bottleneck for the operational application of health assessment. This article systematically analyzes the historical roots and contemporary predicaments of this bottleneck, pointing out that it stems from “technological path dependence”, “verification logic paradox”, and “observation network absence”. To break through this predicament, this article proposes a new biological observation paradigm that will enable the shift from “lagging evidence collection to real-time diagnosis”. This paradigm includes three core dimensions: at the cognitive level, it will survey the “complete species set”, track the “functional fingerprints”, and identify key ecological function signals; at the technical level, it will construct a “real-time perception-quality control verification” collaborative technical system, integrate cutting-edge measures such as environmental DNA, in situ imaging, and intelligent acoustics, and innovatively iterate the verification mode; at the network level, through the development of modular intelligent biological sensing modules, it will embed biological sensing capabilities in the global observation network in an “plug-and-play” manner, achieving automated and continuous perception of biological signals. This paradigm shift aims to upgrade biological observations to a forward-looking information infrastructure that supports real-time health diagnoses and early warnings regarding marine ecosystems.

To investigate the characteristics of the macrobenthic community and its benthic ecological quality in Geligang, a typical intertidal flat in northern Liaodong Bay, 12 stations (including non-harvesting areas, Mactra veneriformis harvesting areas, and Solen grandis harvesting areas) were deployed in the area in June 2024, and macrobenthic fauna and environmental factors were surveyed. Results show that (1) a total of 35 species of macrobenthos were identified, mainly Crustacea (14 species), Mollusca (10 species), and Polychaeta (9 species), of which five species dominated, including Potamocorbula laevis and M. veneriformis; and the community mean abundance and biomass are 163.67 ind./m² and 284.47 g/m² respectively. (2) The cluster analysis and non-metric multidimensional scaling (NMDS) showed that the community similarity between non-harvesting area and M. veneriformis harvesting area was high, while that in the S. grandis harvesting area sits as a separate unit. (3) The Abundance-Biomass Curve (ABC) shows that the macrobenthic community structure in the intertidal flat was stable. The Mantel’s test showed that chlorophyll a and water temperature were important factors on the changes in local macrobenthic community. (4) The benthic ecological quality assessment based on AMBI and M-AMBI indices showed that only a few sites (e.g., No.3) were in moderate or severe disturbance status, and the overall benthic habitat quality was in good condition. The M-AMBI index was better adapted than the single index under the disturbance of mechanized harvesting. This study revealed the benthic ecological status in the intertidal flat, provided a scientific basis for balancing shellfish resource development and habitat protection, and suggested to prioritize the use of the M-AMBI index for long-term monitoring and management assessment.

Marine ecosystem health is under severe pressure. Therefore, scientific and effective evaluation indicators for its assessment and early warning are urgently required. Plankton is a sensitive indicator of ecosystem changes and is critical in the marine food web, supporting important ecosystem services such as carbon sequestration and fishery production. Based on survey data of Jiaozhou Bay from 2003 to 2013, this study screened two types of zooplankton functional group indicators closely related to environmental changes: the dry weight biomass of traditional forage zooplankton (large crustaceans, large copepods, and small copepods), and the dry weight biomass proportion of gelatinous zooplankton (jellyfish, chaetognaths, and tunicates). These indicators represent the productivity level and stability of the functional group structure, respectively. According to the range and thresholds of the historical data, a graded evaluation standard was established. By constructing a two-dimensional coordinate plane based on zooplankton functional group indicators, according to the graded evaluation standard, the historical health status of the ecosystems in Jiaozhou Bay was classified into ecosystems with benign and risky development. These were further subdivided into seven types of health status, namely, rich-product, healthy-sustainable, benign-development, gelatinous-development, gelatinization, high-risk, and resource-scarce. This study provides a typical case using zooplankton functional groups as assessment indicators to establish an assessment system for offshore ecosystem health.

Under the stresses of climate change and anthropogenic activities, marine ecosystems are undergoing unprecedented changes. Accurately assessing the ecological quality status of marine ecosystems and their spatiotemporal variation characteristics is an urgent scientific challenge. Within marine ecological quality assessment frameworks, macrobenthos serve as critical evaluation criteria due to their distinctive physiological and ecological traits. However, current assessment indicators based on macrobenthic communities are numerous yet singular, lacking a comprehensive integrated evaluation system. To address this gap, the present study proposes a multi-dimensional, multi-indicator evaluation framework constructed from an ecological perspective that integrates both community structure and function. This framework comprises three primary categories and nine secondary indices: (1) biotic indices (M-AMBI and BENTIX index); (2) community structure (Shannon-Wiener diversity index, species richness, taxonomic composition, abundance, and biomass); and (3) functional attributes and stability (functional diversity and stability). Weight assignments were allocated according to indicator importance to calculate the macrobenthic community ecological quality index (MCEQI) for benthic ecological status assessment. Application of MCEQI to analyze the macrobenthic community ecological status in Jiaozhou Bay demonstrated that this index exhibits higher accuracy than single-indicator approaches, providing a more comprehensive reflection of community ecological quality.