This study analyses the Ako tidal flat in the Seto Inland Sea, Japan, where nearly all Zostera marina disappeared within a single year in 2025. Using aerial photographs from the 1940s onward, high-resolution satellite imagery, GRUS images (2.5-5 m), and monthly Sentinel-2 composites (10 m), we reconstructed approximately 80 years of seagrass distribution. YOLO-based segmentation using deep learning achieved high accuracy (overall accuracy >= 0.9) across these datasets; although species could not be discriminated, the models captured the major temporal dynamics in vegetation area. The long-term mean seagrass area was 6.8 ha, but values fluctuated widely, from 3.5 ha in 1974 to 41.3 ha in 1989 except 0.2 ha in 2025. Sentinel-2 composites from 2019 to 2026 revealed clear seasonality, with vegetation increasing in early summer and declining from autumn. In 2025, however, the area decreased sharply after summer and remained anomalously low throughout the winter of 2025-2026. Our results, indicating that the 2025 event was not a normal fluctuation but a rapid ecosystem shift involving the loss of the dominant canopy-forming species, most plausibly driven by regionally elevated summer water temperatures. The findings also have implications for seagrass Essential Ocean Variables (EOVs) and the State of Nature (SoN) metrics used in TNFD-aligned nature-related disclosures. Unlike forests, seagrass meadows require finer temporal resolution because both pronounced seasonality and abrupt collapse strongly influence area-based indicators. Therefore, in addition to previously noted issues such as species-level classification accuracy, we recommend that (1) baselines be defined over the longest available record and justified ecologically, (2) seasonal standardization be applied before inter-annual comparisons, and (3) years with extreme area anomalies be flagged rather than used as reference points.

In recent years, clarification of the impacts of marine heatwaves (MHWs) on marine ecosystems has become an important topic. However, most previous studies that have assessed impacts of MHWs have not adequately reduced stochasticity, which has led to insufficient assessment of the direct effects of MHWs. There are also few studies that evaluate the accumulative carryover effects; which occur when the effects of successive events accumulatively increase over time. In addition, many studies have examined the effects of MHWs on abundance, but relatively few on diversity. From 2010 to 2016, southeastern Hokkaido in northern Japan experienced successive MHWs. Here, we assessed the accumulative carryover effects and the impact of MHWs on diversity (species richness and abundance-weighted diversity indices) with reduced stochasticity for four major functional groups (macroalgae, sessile invertebrates, herbivorous mollusks, and carnivorous invertebrates) of rocky intertidal communities. Surveys were conducted before (2004-2009), during (2010-2016), and after (2017-2018) MHWs. We found that the accumulative carryover effects were not detected in diversity. The results demonstrate that MHWs are to lead to accumulative carryover effects on abundance than on diversity. We also found that the direct effects of MHWs on diversity (i.e., increase or decrease of diversity indices during and after MHWs) were different among the four functional groups. These results were due to differences in species composition within the functional groups, such as the proportion of warm water species and cold affinity species and the proportion of dominant species. Thus, multiple metrics should be quantified simultaneously when assessing impacts on MHWs.

The influence of climate change on marine organism abundance has rarely been assessed (1) at the functional-group level; (2) simultaneously in major functional groups within the same ecosystem; (3) for >10 years; and (4) at metapopulation/community scales. A study simultaneously addressing these gaps would greatly enhance our understanding of the influence of climate change on marine ecosystems. Here, we analyzed 21 years of abundance data at the functional-group and species levels on a regional scale for four major functional groups (benthic algae, sessile animals, herbivorous benthos, and carnivorous benthos) in a rocky intertidal habitat along the northeastern Pacific coast of Japan. We aimed to examine the 21-year trends in regional abundance at both functional-group and species levels, plus their driving mechanisms and their dependence on species properties (thermal niche, calcification status, and vertical niche). Significant temporal trends in abundance were detected at functional-group levels for benthic algae (increasing) and herbivores and carnivores (both decreasing); they followed the temporal population trends of the dominant species. At species level, the metapopulation size of 12 of 31 species were increasing and 4 of those were decreasing, depending on the thermal niche and species calcification status. At both functional-group and species levels, temporal trends in abundance are caused by the direct or indirect influence of warming and ocean acidification. Comparing these results with community responses to marine heat waves in the same study area offered two implications: (1) long-term ecosystem changes associated with global warming will be unpredictable from the community response to marine heat waves, possibly owing to a lack of knowledge of the influence of calcifying status on species’ responses to climate change; and (2) thermal niches contribute greatly to predictions of the influence of warming on population size, regardless of the time scale.

AbstractThe impacts of large‐scale disturbance events on the species diversity of rocky intertidal sessile assemblages across multiple spatial scales are not well understood. To evaluate the influence of the 2011 Tohoku Earthquake on alpha and beta diversities of rocky intertidal sessile assemblages, we surveyed sessile assemblages in the mid‐shore zone from 2011 to 2019 and compared the data with those collected from 2003 to 2010 before the earthquake at the same region. The census was conducted across 22 study plots on five rocky shores along 30 km of the Sanriku Coast of Japan, which is located 150–160 km north–northwest of the earthquake epicenter. Alpha diversity was measured with three Hill numbers (H0, H1, and H2), which represent the number of equally common species that would exist in a community with the same diversity as the sampled community, with higher values of the subscript indicating more weight placed on abundant species. Beta diversity was measured with two metrics (BDtotal at two spatial scales). Values were compared between the post‐earthquake period (2011–2019) and the pre‐earthquake period (2003–2010). The results show that the Tohoku Earthquake significantly altered the species diversity of intertidal sessile assemblages across multiple spatial scales. All diversity metrics obtained at multiple spatial scales (i.e., alpha diversities: H0, H1, and H2; beta diversities: BDtotal at the shore and regional scales) decreased immediately after the earthquake and then increased in subsequent years. At 2 years after the earthquake, H0 recovered to within the range of pre‐earthquake values and H1 and H2 became significantly higher than pre‐earthquake values. Most metrics of alpha and beta diversities recovered to pre‐earthquake levels after several years, but regional BDtotal remained low for a longer period.

The frequency and duration of marine heat waves (MHWs) have recently increased. There is therefore an urgent need to understand the response of marine organisms to MHWs. However, most estimates of MHW impacts on abundances include the effects of environmental stochasticity other than the MHWs. In addition, although MHWs sometimes persist for year-round or occur repeatedly for shorter periods, the accumulative carryover effects (ACEs)— the effects of sequential events accumulating additively over time— of MHWs on organisms have never been evaluated. Furthermore, the relationship between species niche traits other than thermal niches and susceptibility to MHWs is unknown. We examined the impacts of MHWs in southeastern Hokkaido, northern Japan, in summer from 2010 to 2016 on rocky intertidal communities by distinguishing MHW effects from environmental stochasticity. We asked (1) Did MHWs have ACEs on four major functional groups: macroalgae, sessile invertebrates, herbivorous invertebrates, and carnivorous invertebrates? (2) Does ignoring ACEs lead to biased assessments? (3) How did the effects of the MHWs on functional groups and their subsequent recovery differ? And (4) How does the susceptibility to MHWs differ with species niche (thermal and vertical) traits? We detected ACEs of MHWs and found that if they are ignored, the effects of MHWs can be underestimated. Although MHWs are known to reduce the abundance of macroalgae and increase that of sessile invertebrates in rocky intertidal habitats, our results show that macroalgal abundance increased during and after MHWs, whereas sessile invertebrates showed no change during or after MHWs. The abundance of herbivorous mollusks decreased during and after MHWs. Carnivorous invertebrates declined during MHWs and in the first year after MHWs. During and after MHWs, abundances of species with low thermal niches decreased and those with high thermal niches increased. There were no differences in response to MHWs between vertical niches when accumulative carryover effects were ignored. These results emphasize the importance of considering ACEs when assessing the response of marine organisms to MHWs, and that more studies of these responses are needed for a variety of ecosystems, regions and organisms to predict the responses of marine organisms.

We present the largest freely available EcoPlate dataset for Japan, comprising data collected from a network of 33 natural forest sites (77 plots) in regions of East Asia ranging from cool temperate to subtropical. EcoPlate is a 96-well microplate that contains three repeated sets of 31 response wells with different sole carbon substrates. The utilization of each carbon substrate by the microbial community is quantified by the color density of the well during incubation. EcoPlate can provide a multifunctional index of a soil microbial community. Soil properties (water content, carbon [C] and nitrogen [N] contents, the C/N ratio, and pH) that are essential for interpreting the EcoPlate results were also measured. The network is part of the Forest and Grassland Survey of the Monitoring Sites 1000 Project established by the Ministry of the Environment. Using a standardized protocol, soil was sampled between September and December 2020. A preliminary principal component analysis was performed on the temporal integration of color density using 31 substrates. For the temporal integration, we calculated the cumulative amount of color development by integrating the color density development curve. PC1 contributed 55.6% and is thought to represent the magnitude of the overall absorbance of all substrates. The model of environmental factors including elevation and the model of soil properties, including water content and pH, were selected as the best-fit models for variation in PC1. EcoPlate data enable the meta-analysis of comparative studies among forest types and testing community ecology and ecosystem function hypotheses at broad spatial scales. The complete data set for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2022-01.1/jalter-en.

We present the largest freely available herbivory dataset for Japan representing data collected from a network of 19 natural forest sites across the country. Sampled network sites were part of the Monitoring Sites 1000 Project organized by the Ministry of the Environment. Sites were located across a range of climate zones, from subarctic to subtropical, and broadleaf trees (both evergreen and deciduous) were targeted at each site. Litterfall traps were used to assess leaf damage caused by leaf-chewing insects in 2014 and 2015. Using a standardized protocol, we assessed herbivory on 117,918 leaves of 39 dominant tree species. Preliminary analyses suggest that insect herbivory increases with increasing latitude for deciduous broadleaf species. In particular, oak (Quercus crispula) and beech (Fagus crenata) were subject to increased insect herbivory with increasing latitude. In contrast, insect herbivory decreased with increasing latitude in evergreen broadleaf species. The latitudinal gradient of herbivory differed according to leaf type (i.e., evergreen or deciduous). This dataset offers excellent opportunities for meta-analysis and comparative studies of herbivory among various forest types. The complete dataset for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at .

Long-term patterns in trajectories of natural communities provide insights into ecological resilience, but their assessment requires long-term census data. We analyzed 16-year census data for intertidal communities from 30 rocky shores along Japan’s Pacific coast to assign community change to four possible trajectories (stable, reversible, abrupt, or linear) representing different aspects of ecological resilience, and to estimate multiple metrics of temporal invariability (species richness, species composition, and community abundance). We examined (1) how the prevalence of the four trajectories differs among regions, (2) how the features (model coefficients) of each trajectory vary among regions, and (3) how the temporal invariabilities differ among trajectories and regions. We found that the stable trajectory was the most common. Its features differed among regions, with a faster recovery to steady-state equilibrium in low-latitude regions. Furthermore, trajectories and temporal invariabilities both varied among regions, seemingly in association with the strength of ocean current fluctuations. Thus, the relationship between community temporal invariability and trajectory may be weak or absent, at least at the regional scale.

In the Fall of 2016 a workshop was held which brought together over 50 scientists from the ecological and radiological fields to discuss feasibility and challenges of reintegrating ecosystem science into radioecology. There is a growing desire to incorporate attributes of ecosystem science into radiological risk assessment and radioecological research more generally, fueled by recent advances in quantification of emergent ecosystem attributes and the desire to accurately reflect impacts of radiological stressors upon ecosystem function. This paper is a synthesis of the discussions and consensus of the workshop participant's responses to three primary questions, which were: 1) How can ecosystem science support radiological risk assessment? 2) What ecosystem level endpoints potentially could be used for radiological risk assessment? and 3) What inference strategies and associated methods would be most appropriate to assess the effects of radionuclides on ecosystem structure and function? The consensus of the participants was that ecosystem science can and should support radiological risk assessment through the incorporation of quantitative metrics that reflect ecosystem functions which are sensitive to radiological contaminants. The participants also agreed that many such endpoints exit or are thought to exit and while many are used in ecological risk assessment currently, additional data need to be collected that link the causal mechanisms of radiological exposure to these endpoints. Finally, the participants agreed that radiological risk assessments must be designed and informed by rigorous statistical frameworks capable of revealing the causal inference tying radiological exposure to the endpoints selected for measurement.

Recognition of bird species by their sounds can bring considerable significance to both ecologists and ornithologists for measuring the biodiversity in the reserves, and studying climate changes. In this letter, we propose an efficient method based on an extreme learning machine (ELM) to classify bird sounds of 86 species of birds in very limited training and testing time. Experimental results prove that, the proposed ELM method can achieve the best recognition performance (81.1 %, unweighted average recall) compared with K‐nearest neighbours (K‐NN), support vector machines (SVM), neural networks (NN), and deep neural networks (DNN) pre‐trained by an autoencoder. In addition, ELM requires the least total time for training and testing (2.047 ± 0.034 s). © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Radiation-contaminated soils are widespread around the Fukushima Daiichi Nuclear Power Plant, and such soils raise concerns over its harmful effect on soil-dwelling organisms. We evaluated the effects of contaminated soil and moss sampled in Fukushima on the embryogenesis and hatching of aphid eggs, along with the measurement of the egg exposure dose. Cs-137 concentration in soil and moss from Fukushima ranged from 2200 to 3300 Bq/g and from 64 to 105 Bq/g, respectively. Eggs of the eriosomatine aphid Prociphilus oriens that were collected from a non-contaminated area were directly placed on the soil and moss for 4 or 3 months during diapause and then incubated until hatching. The total exposure dose to the eggs was estimated as ca. 100-200 mGy in the 4-month soil experiment and 4-10 mGy in the 4-month moss experiment. There was no significant difference in egg hatchability between the contaminated soil treatment and the control. No morphological abnormalities were detected in the first instars that hatched from the contaminated soil treatment. However, we found weak effects of radiation on egg hatching; eggs placed on the contaminated moss hatched earlier than did the control eggs. On the contaminated soil, the effects of radiation on egg hatching were not obvious because of uncontrolled environmental differences among containers. The effects of radiation on egg hatching were detected only in containers where high hatchability was recorded. Through the experiments, we concluded that the aphid eggs responded to ultra-low-dose radiation by advancing embryogenesis.

This paper reports the output of a consensus symposium organized by the International Union of Radioecology in November 2015. The symposium gathered an academically diverse group of 30 scientists to consider the still debated ecological impact of radiation on populations and ecosystems. Stimulated by the Chernobyl and Fukushima disasters' accidental contamination of the environment, there is increasing interest in developing environmental radiation protection frameworks. Scientific research conducted in a variety of laboratory and field settings has improved our knowledge of the effects of ionizing radiation on the environment. However, the results from such studies sometimes appear contradictory and there is disagreement about the implications for risk assessment. The Symposium discussions therefore focused on issues that might lead to different interpretations of the results, such as laboratory versus field approaches, organism versus population and ecosystemic inference strategies, dose estimation approaches and their significance under chronic exposure conditions. The participating scientists, from across the spectrum of disciplines and research areas, extending also beyond the traditional radioecology community, successfully developed a constructive spirit directed at understanding discrepancies. From the discussions, the group has derived seven consensus statements related to environmental protection against radiation, which are supplemented with some recommendations. Each of these statements is contextualized and discussed in view of contributing to the orientation and integration of future research, the results of which should yield better consensus on the ecological impact of radiation and consolidate suitable approaches for efficient radiological protection of the environment.

The Amami Islands in southern Japan host many endemic species, including Amami Jay (Garrulus lidthi). Following the introduction of Small Indian Mongoose (Herpestes auropunctatus) in 1979, populations of Amami Rabbit (Pentalagus furnessi), Amami Woodcock (Scolopax mira), Amami Ishikawa's Frog (Odorrana splendida), and other endemic species declined in the 1990s, as the mongoose expanded its population. A mongoose control project since 2000 successfully reduced the mongoose population to a very low density by 2014, resulting in the initial recovery of severely affected animal populations. Amami Jay was removed from Japan's endangered species list in 2008. However the population and range of Amami Jay are still small (ca. 700 pairs, sometimes with other family member(s), in 700 km2), and other invasive species, such as cats and black rats, continue to damage the native ecosystem. Additionally there is a constant threat of new invasions to the Amami Islands. Our research shows that Amami Jay breeding success depends on the dominant oak (Castanopsis sieboldii) acorn production as much as predation. Therefore conservation plans should consider both short- and long-term effects and potential interaction by both invasive species and other natural factors. Understanding the Amami Jay population dynamics and sustainability from the multiple view points of, such as, population ecology, disease ecology, genetics, and also with ex situ conservation efforts as they relate to invasive species demands, will sophisticate our ecosystem research and management. We discuss how this endeavor of ours might develop as a model activity for maintaining biodiversity under threat from multiple invasive species.

The Fukushima-Daiichi Nuclear Power Plant (F1NPP) accident is an IAEA level 7 event, the same as that of Chernobyl, while the amount of radionuclides released is not comparable. Radioactivity attributed to the F1NPP accident was detected 250 km away from the F1NPP. Although we have not yet systematically studied the effect of radionuclides on the environment and wildlife, one of three Japanese Bush Warblers (Cettia diphone), captured in Akaugi district in August 2011, was observed to have a conspicuous lesion near the cloaca, which is rare in Japan. All of the birds' feathers were strongly contaminated. Further study is needed to determine the significance of this result. We emphasize the importance of continuing assessment of the effects of the F1NPP accident on wildlife.

Wildlife populations on Amami Island, Japan, have been affected by forest clear-felling and the introduction of alien species, in particular the mongoose Herpestes auropunctatus. We used monitoring data collected over 24 years to track changes in the population sizes of five species of mammals and 20 species of birds. We assigned species to the following groups: indigenous, rare, insectivorous, negatively affected by forest clear-cutting, and negatively affected by mongoose invasion. We examined trends in each group at four time points between 1985 and 2010 using two methods: species abundance estimates and the Living Planet Index. We then assessed the usefulness of these methods as tools for conservation planning. Inspecting species individually we identified four main patterns of abundance change: (a) an increase from the first to the last census period, (b) an increase in all periods except 2009-2010, (c) a decrease from 1985-1986 to 2001-2002 but an increase in 2009-2010, and (d) a decrease in all census periods. We observed certain relationships between these patterns and the species groups assigned as above. According to the Living Planet Index the group negatively affected by forest clear-cutting did not show significant recovery and the groups of rare species and species negatively affected by mongoose recovered to c. 40% of the original level after a sharp decline during 1985-2002. The Living Planet Index is a more useful tool for assessing the urgency of particular conservation needs, although limited information on species abundance reduces its representativeness for some groups.

This data paper reports litter fall data collected in a network of 21 forest sites in Japan. This is the largest litter fall data set freely available in Japan to date. The network is a part of the Monitoring Sites 1000 Project launched by the Ministry of the Environment, Japan. It covers subarctic to subtropical climate zones and the four major forest types in Japan. Twenty-three permanent plots in which usually 25 litter traps were installed were established in old-growth or secondary natural forests. Litter falls were collected monthly from 2004, and sorted into leaves, branches, reproductive structures and miscellaneous. The data provide seasonal patterns and inter-annual dynamics of litter falls, and their geographical patterns, and offer good opportunities for meta-analyses and comparative studies among forests.