Thomas Lamy

Micronutrient deficiencies are prevalent in Madagascar, where diets rely heavily on starchy staples and access to animal-source foods is limited. Small dried fish (SDF) are widely available, yet their nutritional value and health risks remain poorly documented. We combined market surveys, taxonomic identification, and micronutrient and heavy metal analyses of nine SDF types collected along National Road 7. The samples encompassed 33 fish families, were dominated by small pelagic species (Clupeidae and Engraulidae), and were appreciated by consumers. A daily portion (5 g for infants; 10 g for young children and women of childbearing age) contributed substantially to Recommended Nutrient Intakes (RNIs). Across samples and groups, SDF were rich (>30% of RNI) in selenium and, for infants and young children, in calcium. All samples were a source of (>15% of RNI), or rich in, phosphorus, whereas iron contributions were more variable but often substantial. Several samples exceeded 100% of RNIs for selenium, calcium, iron, or manganese in infants and young children, and some were also sources of magnesium and, less frequently, zinc. Vitamin A was absent from sun-dried samples but detected in a smoked freshwater type. Heavy metal concentrations varied markedly, and portions of several types led to estimated exposures to inorganic arsenic or cadmium exceeding reference values, whereas freshwater species and some pelagic types showed a more favorable nutrition-risk balance. Overall, SDF are affordable, nutrient-dense foods with strong potential to alleviate micronutrient deficiencies in Madagascar, while highlighting the need for type-specific guidance to balance nutritional benefits and contamination risks.

Environmental DNA (eDNA) metabarcoding produces sparse read-count matrices routinely binarised to presence/absence to mitigate amplification, copy-number and shedding biases. We argue that binary eDNA data are sufficient to recover detailed community structure, sparse indicator panels and habitat-specific co-occurrence sub-networks — given the right analytical pipeline. Yet integrative frameworks bridging taxon-level and community-level structure remain missing for macro-organism eDNA. We propose a reproducible framework combining three scales: sparse machine-learning indicator-species identification (Predomics), consensus co-occurrence network inference (ScaleNet), and module-level enrichment via Gene Set Enrichment Analysis (GSEA). We applied it to 217 eDNA samples spanning eight habitats and three depth zones (shallow, <50 m; middle, 50–250 m; deep, 200–600 m) in New Caledonia, South Pacific. A sparse 55-MOTU indicator panel captured a proportion of beta-diversity variance comparable to the full 318-MOTU community. ScaleNet reconstructed a 261-node, 579-edge network with a core-periphery main component (shallow in the core, middle at the periphery) and a structurally isolated deep-zone subgraph. Fast-Greedy modularity partitioned it into 13 modules, 11 significantly enriched for depth zones or habitats by GSEA, each mapping onto a coherent trophic guild — from mesopelagic lanternfishes over deep seamounts to reef grazers across shallow microhabitats. Indicator taxa occupied structurally peripheral positions while connectivity hubs were non-indicator generalists, with reef-scraping parrotfish a functionally important exception. Sparse indicator panels efficiently capture zone discrimination while co-occurrence networks reveal community-level integration — together providing a scalable, interpretable framework for eDNA-based marine biodiversity monitoring.

Small‐scale fisheries are vital for the livelihoods, nutrition and well‐being of millions of people in coastal regions. In many parts of the Global South, rising poverty, limited alternatives and declining resources have driven the spread of mosquito net fishing (MNF), a non‐selective practice using repurposed health‐distributed nets. While MNF raises serious ecological concerns and is widely prohibited, it remains prevalent. This persistence highlights a fundamental paradox and raises critical questions about the social, economic and ecological trade‐offs shaping fishing decisions in vulnerable coastal communities. To explore this paradox, we applied an integrated framework addressing four interlinked and understudied facets of MNF: (1) fishers' motivations, (2) the diversity of realized benefits, (3) the roles of women, and (4) value chain structure. We focused on Ranobe Bay, southwest Madagascar, where livelihood insecurity, changing fishing practices and ecological degradation intersect. Using a mixed‐methods approach, we combined semi‐structured interviews with 84 fishermen and fisherwomen, a five‐month catch survey, and a post‐landing survey tracking destination, uses, and income from 35 catches. MNF was practised by both Vezo and Masikoro fishers, including migrants, with 60% citing poverty and affordability as primary motivations. Despite social stigma and spatial exclusion, MNF supported daily catches of 8.8–17.7 kg and 379 morpho‐species, with an average size of 4.9 cm. Households retained 10% of catches for consumption—primarily preferred, larger and inexpensive species—supporting frequent fish intake (5–7 meals per week) among 83% of fishers. Most catches (88%) were sold fresh, either locally or in nearby markets, while only 2% were processed. Women played key roles throughout fishing and trade, strengthening their economic agency and household contributions. Nevertheless, incomes remained below the poverty line, and ecological impacts were evident. The MNF paradox lies in its provision of immediate economic and nutritional benefits, while simultaneously exacerbating long‐term ecological degradation and reinforcing poverty and marginalization. In the absence of viable alternatives, MNF constitutes a socio‐ecological trap, where short‐term survival strategies undermine future livelihood security and ecosystem resilience. Addressing it requires integrated solutions that combine poverty alleviation, gender equity and inclusive governance to support both livelihoods and ecosystem sustainability. Read the free Plain Language Summary for this article on the Journal blog.

Fishers’ spatial knowledge encompasses a diverse array of social, ecological, technical, experiential, and learning knowledge derived from local environmental and sociocultural contexts. In this study, we used a transdisciplinary framework to shed light on place names of fishing grounds in the context of small-scale fisheries through a case study in Madagascar. First, we jointly monitored fishing boat trajectories based on GPS tracking and recorded the vernacular names of fishing sites in a coral reef fishery from May 2018 to April 2019. This data was processed through spatial analysis to assess the dimensions of each named fishing site. A focus group discussion was conducted with fishers to determine the literal meanings of the toponyms (place names) in the local language. A total of 570 fishers (totaling 15,904 fishing trips) using five gear types were surveyed in eight communities. We identified 397 fishing sites over about 250 km², 304 of which (76.6%) were mapped. Overall, 371 toponyms (93.4%) were interpreted and categorized based on geographical features (n = 222), biodiversity (n = 86), and maritime uses (n = 63). The dimensions of the fishing sites varied significantly from 0.01 to 11.7 km², following spatially-explicit fishing distribution patterns and the level of precision of the delimitation method. Most fishing locations (63.3% of the total fishing grounds) were associated with multiple place names, particularly in heavily-targeted areas, indicating that individual fishers typically have their own names for their fishing sites. This study demonstrates that recording boat movements and vernacular toponyms simultaneously throughout an extensive monitoring survey in a coral reef fishery, effectively captured the rich and varied individual fishers’ conceptualizations of the coastal and nearshore marine environment. Our findings suggest that named fishing sites may be used as local spatial reference units with known precision and accuracy, which is relevant for addressing spatial data limitations in small-scale fisheries and incorporating fishers’ knowledge in collaborative fisheries science.

The rapid melting of mountain glaciers and the vanishing of their streams is emblematic of climate change^1,2. Glacier-fed streams (GFSs) are cold, oligotrophic and unstable ecosystems in which life is dominated by microbial biofilms^2,3. However, current knowledge on the GFS microbiome is scarce^4,5, precluding an understanding of its response to glacier shrinkage. Here, by leveraging metabarcoding and metagenomics, we provide a comprehensive survey of bacteria in the benthic microbiome across 152 GFSs draining the Earth’s major mountain ranges. We find that the GFS bacterial microbiome is taxonomically and functionally distinct from other cryospheric microbiomes. GFS bacteria are diverse, with more than half being specific to a given mountain range, some unique to single GFSs and a few cosmopolitan and abundant. We show how geographic isolation and environmental selection shape their biogeography, which is characterized by distinct compositional patterns between mountain ranges and hemispheres. Phylogenetic analyses furthermore uncovered microdiverse clades resulting from environmental selection, probably promoting functional resilience and contributing to GFS bacterial biodiversity and biogeography. Climate-induced glacier shrinkage puts this unique microbiome at risk. Our study provides a global reference for future climate-change microbiology studies on the vanishing GFS ecosystem.

Biodiversity can stabilize ecological communities through biological insurance, but climate and other environmental changes may disrupt this process via simultaneous ecosystem destabilization and biodiversity loss. While changes to diversity–stability relationships (DSRs) and the underlying mechanisms have been extensively explored in terrestrial plant communities, this topic remains largely unexplored in benthic marine ecosystems that comprise diverse assemblages of producers and consumers. By analyzing two decades of kelp forest biodiversity survey data, we discovered changes in diversity, stability, and their relationships at multiple scales (biological organizational levels, spatial scales, and functional groups) that were linked with the most severe marine heatwave ever documented in the North Pacific Ocean. Moreover, changes in the strength of DSRs during/after the heatwave were more apparent among functional groups than both biological organizational levels (population vs. ecosystem levels) and spatial scales (local vs. broad scales). Specifically, the strength of DSRs decreased for fishes, increased for mobile invertebrates and understory algae, and were unchanged for sessile invertebrates during/after the heatwave. Our findings suggest that biodiversity plays a key role in stabilizing marine ecosystems, but the resilience of DSRs to adverse climate impacts primarily depends on the functional identities of ecological communities.

Selective logging is one of the most prevalent land uses of forests worldwide, affecting biodiversity and ecosystem functioning. However, the effect of selective logging on the dual nature of temporal stability, and the scale dependence of this effect, remain to be elucidated. By conducting several decade‐long experiments in temperate forest ecosystems, we tested the effects of selective logging on aggregate and compositional stability at multiple spatial scales. As expected, forest ecosystem stability at larger spatial scales was enhanced both by the stability of local scales (i.e. α stability) and asynchronous dynamics among local communities (i.e. spatial asynchrony). We found that the negative effects of selective logging on both facets of forest stability propagated from local to larger spatial scales due to reduced α stability and the biological insurance effects of α diversity. However, both spatial aggregate and compositional asynchrony were not affected by selective logging. Interestingly, despite the selective logging, α diversity still provided biological insurance effects for maintaining aggregate and compositional stability. Our results imply that selective logging may destabilize the aggregate ecosystem functioning and species composition of forest ecosystems at local and larger spatial scales. To our knowledge, this study provides the first evidence of the scale dependence of aggregate and compositional stability of forest ecosystems in response to selective logging. Our findings suggest that forest management should avoid excessive selective logging and strive to protect forest diversity to safeguard the sustainability of the functioning and composition of natural forest ecosystems at multiple spatial scales. Keywords: aggregate stability, compositional stability, diversity, ecosystem functioning, spatial asynchrony, stability

The relationship between biodiversity and stability, or its inverse, temporal variability, is multidimensional and complex. Temporal variability in aggregate properties, like total biomass or abundance, is typically lower in communities with higher species diversity (i.e., the diversity–stability relationship [DSR]). At broader spatial extents, regional‐scale aggregate variability is also lower with higher regional diversity (in plant systems) and with lower spatial synchrony. However, focusing exclusively on aggregate properties of communities may overlook potentially destabilizing compositional shifts. It is not yet clear how diversity is related to different components of variability across spatial scales, nor whether regional DSRs emerge across a broad range of organisms and ecosystem types. To test these questions, we compiled a large collection of long‐term metacommunity data spanning a wide range of taxonomic groups (e.g., birds, fish, plants, invertebrates) and ecosystem types (e.g., deserts, forests, oceans). We applied a newly developed quantitative framework for jointly analyzing aggregate and compositional variability across scales. We quantified DSRs for composition and aggregate variability in local communities and metacommunities. At the local scale, more diverse communities were less variable, but this effect was stronger for aggregate than compositional properties. We found no stabilizing effect of γ‐diversity on metacommunity variability, but β‐diversity played a strong role in reducing compositional spatial synchrony, which reduced regional variability. Spatial synchrony differed among taxa, suggesting differences in stabilization by spatial processes. However, metacommunity variability was more strongly driven by local variability than by spatial synchrony. Across a broader range of taxa, our results suggest that high γ‐diversity does not consistently stabilize aggregate properties at regional scales without sufficient spatial β‐diversity to reduce spatial synchrony.

Nearly 60% of the world’s glaciers are predicted to be lost by the end of the century because of global warming1. The impacts of this environmental change on the glacier-fed stream (GFS) ecosystems are profound, putting their ecological communities at risk^2–4. Life in GFSs is dominated by benthic microbial biofilms, which regulate key ecosystem processes and form the basis of the food web⁵ . However, the biodiversity and biogeography of the biofilm microbiome of the world’s GFSs remain unknown, precluding a mechanistic understanding of its responses to glacier shrinkage. Here, applying metabarcoding to the benthic biofilm bacteria from 148 GFSs draining the world’s major mountain ranges, we unveil their global biodiversity and biogeography. We find that the global GFS benthic microbiome differs from other cryospheric microbiomes and is unexpectedly diverse. A large microbiome fraction (58% of the total amplicon sequence variants) is endemic to single mountain ranges, while 0.4% are disproportionately abundant and form a cosmopolitan core. These microbiome components have overlapping taxonomies, but their compositional turnover is differently shaped by dispersal limitation and environmental selection. Phylogenetic analyses relate prevalent clades to endemicity and microdiversity, the latter potentially buffering the GFS microbiome against climate-change impacts. Our global survey provides the basis for future climate-change microbiology studies⁶ on a rapidly changing ecosystem.

Our planet is facing a variety of serious threats from climate change that are unfolding unevenly across the globe. Uncovering the spatial patterns of ecosystem stability is important for predicting the responses of ecological processes and biodiversity patterns to climate change. However, the understanding of the latitudinal pattern of ecosystem stability across scales and of the underlying ecological drivers is still very limited. Accordingly, this study examines the latitudinal patterns of ecosystem stability at the local and regional spatial scale using a natural assembly of forest metacommunities that are distributed over a large temperate forest region, considering a range of potential environmental drivers. We found that the stability of regional communities (regional stability) and asynchronous dynamics among local communities (spatial asynchrony) both decreased with increasing latitude, whereas the stability of local communities (local stability) did not. We tested a series of hypotheses that potentially drive the spatial patterns of ecosystem stability, and found that although the ecological drivers of biodiversity, climatic history, resource conditions, climatic stability, and environmental heterogeneity varied with latitude, latitudinal patterns of ecosystem stability at multiple scales were affected by biodiversity and environmental heterogeneity. In particular, α diversity is positively associated with local stability, while β diversity is positively associated with spatial asynchrony, although both relationships are weak. Our study provides the first evidence that latitudinal patterns of the temporal stability of naturally assembled forest metacommunities across scales are driven by biodiversity and environmental heterogeneity. Our findings suggest that the preservation of plant biodiversity within and between forest communities and the maintenance of heterogeneous landscapes can be crucial to buffer forest ecosystems at higher latitudes from the faster and more intense negative impacts of climate change in the future.