Regeneration, the ability to restore lost or damaged tissues, organs, or entire body structures, represents one of the most profound biological phenomena shared across life on Earth. From plants and animals that regrow entire organisms from small tissue fragments to organisms capable of rebuilding complex organs, regeneration challenges long-standing assumptions about biological limits. The launch of the Journal of Regeneration (JoR) reflects a growing recognition that regeneration is not a niche specialty but a transversal biological principle connecting developmental biology, evolution, ecology, agriculture, and medicine. JoR is founded on the premise that understanding regeneration requires exploration across kingdoms of life and across disciplines, ranging from molecular genetics to clinical translation. It aims at becoming a vehicle that publishes and disseminates scientific production in this wide-range field of inquiry. This editorial outlines the historical foundations of regeneration research, highlights insights gained from diverse model systems, explores how fundamental discoveries inform medicine, and considers the future trajectory of this rapidly advancing field.

Marine Animal Forests (MAFs), among the largest biomes on Earth, represent ecologically and economically important ecosystems. Their structural complexity, engineered by sessile organisms, supports high biodiversity and multiple ecosystem services. Despite growing restoration efforts, MAFs remain excluded from biodiversity credit markets due to the absence of standardized, ecosystem-specific metrics for quantifying ecological gains. Here we introduce the Sessile Transplants Biodiversity Index (STBI), an applied framework for quantifying biodiversity gains associated with restoration interventions to support biodiversity crediting in MAFs. The STBI integrates key ecological and restoration parameters, such as species richness and diversity, abundance, genotypic diversity, colony size, and spatial extent, into a transparent and modular index. Initially developed for coral reefs but adaptable to other MAF benthic habitats, the index requires an explicit ecological baseline for one biodiversity credit, ensuring proportional crediting across projects and contexts. We demonstrate that the STBI captures biodiversity dimensions often overlooked by conventional diversity indices and converts them into biodiversity credits. Through simulations of synthetic communities and two empirical case studies, we show that the STBI framework rewards restoration designs that promote balanced species representation, genetic variability, and habitat complexity. By offering a standardized and scalable framework, the STBI links ecological recovery and its associated ecosystem service potential under global change to measurable outcomes. This represents one of the first operational tools directly connecting measurable MAF biodiversity gains in restoration and conservation programs to emerging nature markets. The STBI may complement existing biodiversity crediting initiatives by providing a standardized, auditable, and scalable index tailored to sessile marine ecosystems that aligns with the Kunming-Montreal Global Biodiversity Framework.

Coral transplantation has become a key restoration strategy in response to widespread reef degradation, yet the ecological roles of outplanting density and species interactions are rarely applied in practice. Here we transplanted in Wuzhizhou Island, China, 1728 coral fragments from three common reef-building species (Pocillopora damicornis, Acropora microphthalma, Porites cylindrica) on Frame Reef Modules (FRM; 30 cm above substrates) using cable ties. We established 6 replicates for the combinations: low density (16 colonies/FRM), high density (32 colonies/FRM), monocultures (single species/FRM) and polycultures (2 species/FRM). FRMs were monitored for 458 days to test how density-dependent interactions shape restoration outcomes and microbial succession. Employing the relative interaction intensity index, coral fragments showed higher survival and steady growth rates under high-density monoculture conditions, indicating that intraspecific facilitation, rather than interspecific interactions, drives success. Using coral-associated bacterial data, we built machine learning models linking microbiome composition to coral growth, identifying core taxa and microbial indicators responsive to density and culture type. Collectively, our findings show that conspecific aggregation improves transplantation performance, supports microbiome-informed growth prediction, and highlights the value of applying ecological principles to enhance restoration success and cost-efficiency.

Coral reefs are experiencing rapid degradation driven by climate change and human-induced pressures, highlighting the urgent need for active restoration. A lagoon-based coral nursery was established at La Cambuse, Mauritius, where 671 coral fragments were deployed across 55 hexagonal 'spider' frames (three sets) and four elevated tables and observed over a 15-month period. Set 2 frames showed the highest survivorship (77.3%), with Pocillopora sp. outperforming Acropora spp. in both thermal tolerance and growth rates (23.59 cm2 year-1 vs. 12.84-16.49 cm2 year-1). A coral bleaching event in March 2025 severely impacted Acropora spp., with up to 60% tissue loss, while Pocillopora spp. demonstrated strong resilience showing minimal pigment loss and 77.3% survivorship on Set 2 frames. Over 100 naturally recruited corals were observed, indicating favourable larval settlement conditions. Biodiversity assessments recorded 105 reef-associated species, including 65 fish, 11 echinoderms and 14 macroalgae, with 10 species listed as conservation priorities. Biodiversity indices remained stable (Shannon-Wiener H ' = 2.69-3.01; Pielou's J ' = 0.81-0.88), and trophic structure analysis revealed a succession pattern, from herbivore dominance in early stages to increasing carnivores at following stages. Fishing line entanglements highlighted ongoing anthropogenic stress on the nursery reef. Overall, findings emphasise the species-specific resilience and demonstrate the potential of adaptive coral nurseries as both restoration tools and biodiversity support systems in the face of accelerating climate change in the Western Indian Ocean. The result also put La Cambuse site as a 'Forethoughtful Coral Nursery', serving novel functions, beyond the traditional use of coral propagation for transplantation.

The discipline of coral reefs restoration is advancing rapidly in response to accelerating global degradation, however, many current practices remain reactive, technique-driven, and often lack integration with ecological theory. Here, we promote ecological facilitation as a valuable yet underused framework for guiding coral reef restoration. Drawing insights from well-established terrestrial restoration principles, we show how three key ecological facilitation processes, herbivore-controlled competition, density-dependent interactions, and habitat provisioning are already embedded, though often overlooked, in current coral restoration practices. An overview of recent studies reveals that facilitative mechanisms often drive positive outcomes like increased transplant survival, reduced algal cover, and enhanced biodiversity. By reframing coral gardening and related interventions through the lens of ecological facilitation, we offer a more predictive and functionally integrated pathway for reef restoration. We outline practical consideration for implementation and encourage future research to experimentally test facilitation thresholds, optimal species combination, and integrated restoration designs. Ecological facilitation offers a vital link between theory and practice, providing a roadmap for developing more resilient and effective restoration strategies.

Marine invertebrate cell cultures are a potential source for diverse biotechnological applications, given the wide range of bioactive compounds they synthesize and accumulate. Yet, the number of established marine invertebrate cell culture systems remains limited compared with those of insects and vertebrates, particularly with respect to adherent cell cultures. Here we studied the in vitro adherence of circulating blood cells from the colonial ascidian Botryllus schlosseri. Two experimental approaches were employed, seeding blood cells either alone (setup 1) or in combination with tissue fragments (setup 2), using three basal media (DMEM, DMEM/F-12, RPMI) on culture plates coated with either Poly-L/D-lysine, gelatin, collagen, or laminin. Each experiment lasted for up to 3 d. Setup 1 results reveal that Botryllus cells remain viable and can adhere to coated surfaces in all tested media. Collagen- and laminin-coated plates supported longer-term cultures, whereas Poly-D (or L)-lysine coatings were more suitable for short-term studies. Among the basal media, RPMI and DMEM/F12 most effectively supported cell attachment. Setup 2 plates consistently showed higher cell adherence compared to setup 1, suggesting that tissue-derived factors may enhance attachment. Overall, circulating Botryllus cells demonstrate the capacity for substrate adhesion in vitro, offering a foundation for the development of adherent cell cultures.

Widespread coral reef degradation in the Western Indian Ocean (WIO) underscores the need to support restoration to accelerate recovery in severely impacted areas. Restoration science in the WIO remains nascent, with few small-scale initiatives and limited integration between reef managers, practitioners, and researchers, hindering effective coordination of efforts toward larger-scale action. This study aimed to consolidate knowledge on WIO coral restoration initiatives, identify lessons learned, and assess current practices to inform future coordination and scaling efforts. We focused on (i) approaches and techniques used, (ii) lessons from successes and failures, and (iii) the potential role of a regional practitioner network in addressing identified gaps. Data were compiled from peer-reviewed literature, online sources, a WIO practitioner survey, and a regional workshop. Results indicate growing momentum for coral reef restoration, particularly in Kenya, Tanzania, and the Seychelles, with an increase in publications since 2021. Twenty-two active initiatives were identified across eight countries; 76% involved local communities, and 27% were fully community-led. Asexual methods like coral gardening dominated due to cost-effectiveness, while sexual propagation was limited to Seychelles and planned for Mauritius. Initiatives primarily targeted fast-growing genera such as Acropora and Pocillopora, with limited species diversity. Monitoring practices were highly variable, with most projects relying on short-term ecological indicators and few reporting standardized quantitative metrics such as survival rates or restoration footprint. While 86% of projects collected ecological baseline data, only 38% included socio-economic indicators. The synthesis of findings contributed to the establishment of the Western Indian Ocean Coral Reef Restoration Network (WIOCRRN), a regional platform guided by the Capacity, Access, Research, and Enhancement ("CARE") framework, aimed at advancing resilient and sustainable reef ecosystems while aligning conservation outcomes with the socio-economic needs of coastal communities. The uneven geographic distribution of initiatives and documented data gaps highlight opportunities for improved coordination, standardization, and strategic scaling of restoration efforts across the region.

Coral restoration technologies are vital for rehabilitating degraded coral reefs, with the gardening approach used as the main global method. However, the success of these efforts depends on restoration-related factors, including coral species selection, fragment size, and transplant density. Here we monitored for over one year period fragments of opportunity from four coral species, Acropora hyacinthus, Acropora microphthalma, Porites cylindrica, and Montipora digitata, that were transplanted on "Framed Reef Modules" located at Wuzhizhou Island, Hainan, China. The fragments were divided into three groups, representing three fragment sizes and two spacing regimens, in four replicates: Group 1 (6 cm size; 16 colonies; spacing 30 cm), Group 2 (3 cm; 32 colonies; spacing 15 cm), Group 3 (6 cm; 32 colonies; spacing 15 cm). Coral survival, growth rates, and physiological parameters were continuously monitored. In A. hyacinthus and P. cylindrica, large fragment size and lower transplant density significantly enhanced growth and survival rates. Under high-density transplant condition, smaller A. microphthalma fragments exhibited higher survival rates. Lower density transplantation significantly improved the survival rate of M. digitata, while its growth rate was not affected by either fragment size or transplant density. Environmental factors, such as seawater temperature, turbidity, and nutrient concentrations, significantly affected coral growth during the 90 to 180 days post-transplantation, when increased environmental stress inhibited coral growth rates. This study adds to our understanding of the selection of fragment size and spacing in direct active transplantation of corals of opportunity.

One of the major accomplishments of the 20th century is the advancement of pharmaceuticals to treat a variety of diseases and metabolic disorders. Traditionally, nature has served as the primary source for new pharmaceuticals, with over 50% of marketed drugs either derived directly from natural sources or synthesised using natural products as templates or starting materials. The ocean is home to more than 200,000 described species of marine invertebrates, representing every phylum, including twelve phyla that are exclusively marine. More than 15,000 novel marine-derived chemicals have been reported, many of which have potential pharmaceutical applications. Many of these compounds occur in marine organisms at very low concentrations and their often complex molecular structures make them difficult to be chemically synthesised, which has created a bottleneck in their development as drugs. Scientists have spent decades, without success, working to develop alternative supply options, including in vitro culturing of marine invertebrates or cell cultures. The objective of BLUES is to expand the potential to produce valuable and unique bioactive compounds from marine invertebrates by developing novel in vitro cell culture systems for four phyla of marine invertebrates (Porifera, Cnidaria, Echinodermata, Chordata) and optimising production yields as an alternative to wild harvesting and chemical synthesis. The goal is to design a pathway towards industrial bioprocesses using cell lines as a chassis to produce unique, high-value, marine bio-based compounds. The novel bioprocesses will solve the supply bottleneck for increased availability of bioactive compounds, but also for a higher level of sustainable alternatives, contributing to the development of circular processing and a circular economy.The BLUES project is supported by the Horizon Europe, European Union research initiative, project number: 101134820.

Coral body plans are constructed through repeated modular units, with polyps serving as the fundamental structural and functional units, yet the rules underlying tissue and polyp pattern formation remain poorly understood. This study investigated lateral, two-dimensional (2D) tissue and polyp expansion in the coral Stylophora pistillata under controlled laboratory conditions. Using the nubbin assay, we investigated the effects of colony, fragment origin (branch tips versus sub-apical fragments), and nubbin density on this 2D expansion assay. Nubbins from ten colonies (SC1–SC10) were grown on glass slides, and tissue expansion was quantified from digital images over six months. For three fast-growing colonies (SC1, SC2, and SC5), single-, double-, and triple-nubbin configurations were used to evaluate proximity effects. Across all colonies, lateral tissue area strongly correlated with polyp number (R2 = 0.68), indicating a close relationship between surface expansion and polyp proliferation. Pronounced colony differences emerged: SC9 and SC1 exhibited the largest tissue areas, while SC5 developed compact, polyp-dense morphologies. Fragment origin did not influence 2D growth, suggesting the absence of apical dominance. Nubbin density influenced growth in a colony-specific manner; SC1 exhibited strong inhibition under crowded conditions, whereas SC2 and SC5 were largely unaffected. Collectively, these results suggest that intrinsic genetic factors and local spatial interactions, rather than a fragment’s position along a branch, are the primary drivers of 2D growth, highlighting the self-organizing nature of coral tissues and illustrating how controlled 2D systems can clarify the interplay between genetic regulation and local interactions in coral morphogenesis.

The widely invasive brown mussel Perna perna reappeared along the Mediterranean coast of Israel in 2020, 55 years after a previous short-lived presence. Within a year, the mussel formed patchy but dense aggregations, before suffering catastrophic mortality following an extended mid-summer heatwave in August 2021. The emergent post-mortality population structure was studied over a 3-year period at four sites of varying emersion and sedimentation conditions. The collected data (8,560 mussels) exhibit distinct patterns in population abundance and size structure in response to local natural and manmade features. At a sediment-free site, spat was observed already in January; on low-lying rocky outcrops settlement began as soon as winter storm-induced sand accumulation cleared, whereas in outcrops reburied by beach nourishment, settlement surges were delayed until sediment cleared. Sites submerged for shorter periods exhibited a unimodal distribution and lacked the larger-size cohort observed at the lower intertidal. An examination of mitochondrial cytochrome c oxidase subunit I gene (42 specimens) revealed no significant changes in haplotype diversity between pre-and post-marine mortality events in this genetically highly polymorphic species, indicating recovery resulting from a remnant population. With an increasing number of marine invasive non-indigenous species, information on their introduction and settlement patterns is essential for guiding environmentally sensitive policies and conservation efforts.

Coastal vegetated ecosystems such as mangroves and salt marshes are established blue carbon sinks. In contrast, animal-based marine ecosystems, particularly coral reefs, are often excluded from carbon mitigation frameworks and remain the subject of ongoing debate. Here, we present a proof-of-concept for a Floating Reef Device (FRD), a modular mid-water coral-based structure designed to evaluate the carbon accumulation and storage in open-sea environments. Using empirical measurements from a 100 m2 prototype FRD deployed in the oligotrophic waters of the northern Red Sea, and seeded with nubbins of the model Stylophora pistillata, we quantified approximately 351.38 kg of organic and 195.7 kg of inorganic carbon pools associated with the FRD after one year. Of the organic carbon pool, around 345 kg (98%) was associated with transient fish biomass representing a short-term ecosystem-associated carbon pool, whereas approximately 6.4 kg was directly attributed to corals and sessile benthic organisms that constitute longer-lived structural carbon pools. Coral photosynthesis and skeletal growth were the primary drivers of carbon accumulation, with additional contributions from associated biota. Our findings provide empirical evidence that FRDs can support measurable carbon accumulation, expanding discussions of blue carbon perspectives beyond vegetated habitat while highlighting the need to distinguish among carbon pools with different residence times. This proof-of-concept establishes a quantitative groundwork for future evaluations of the ecological and socio-economic importance of animal-based marine ecosystems.

Based on COI analyses of three medusae collected in Dar es Salaam, Tanzania, and on a low-resolution photograph of a jellyfish swarm in Haifa Port, Kuplik et al. [...]

Advanced methodologies for Botryllus schlosseri artificial seawater systems are needed to decrease dependency of large-scale culture on natural seawater and expand this important new model organism to more inland laboratories. We constructed two botryllid tunicate customized closed aquaculture systems, a static system consisting of aerated jars fed commercial filter feeder diet, and a recirculating aquaculture system (RAS) consisting of pertinent marine RAS components fed live microalgae and zooplankton diets. Initially, static tunicate culture yielded exponential growth in contrast to poor survival and negligible growth observed in RAS tunicates. RAS modifications were made to increase water treatment proficiency, which improved tunicate survival and growth. Experiments were performed isolating feed and water type as variables differentiating static and RAS and evaluating their specific effects. Live feed promoted five-fold greater growth relative to a commercial concentrate diet. Tunicates maintained in optimized RAS water achieved two-fold faster growth relative to animals in freshly prepared artificial seawater. Subsequent procedural modifications combined with the RAS revisions resulted in growth rates comparable to the static system. Both optimized systems are suitable for long-term husbandry of botryllid tunicate populations supporting both sexual and asexual modes of reproduction, with a current RAS residence time of over 24 months.

Despite decades of progress, long-term outcomes in human organ transplantation remain challenging. Functional decline in transplanted organs has stagnated over the past two decades, with most patients requiring lifelong immunosuppression, therapies that overlook the principles of self/non-self recognition and natural transplantation events in humans. To address these discrepancies, this perspective proposes that immunity evolved not as pathogen-driven but as a mechanism to preserve individuality by preventing invasion from parasitic conspecific cells. It further reveals that the concept of “self/non-self” recognition encompasses multiple theories with complex and often ambiguous terminology, lacking precise definitions. In comparisons, natural historecognition reactions in sessile marine invertebrates are regulated by a wide spectrum of precise and specific allorecognition systems, with transitive and non-transitive hierarchies. Using the coral Stylophora pistillata and the ascidian Botryllus schlosseri as models, it is evident these organisms distinguish ‘self’ from ‘non-self’ with remarkable accuracy across various allogeneic combinations, identifying each non-self entity while simultaneously recognizing selfhood through transitive allogeneic hierarchies. Their allorecognition offers an improved explanation for post-transplant outcomes by accounting for the natural dynamic, spatiotemporal evolution of selfhood. To bridge natural (in invertebrates and humans alike) and clinical transplantation phenomena, the ‘allorecognition landscape’ (AL) metaphor is proposed. This unified framework conceptualizes self/non-self recognition as shaped by two dynamic continuums of ‘self’ and ‘non-self’ nature. Throughout the patient lifespan, the AL represents diverse and transient arrays of specific ‘self’ and ‘non-self’ states (including reciprocal states) that shift over time in either recognition direction, requiring adaptable clinical strategies to address their evolving nature.

The ascidian Boytryllus schlosseri is a marine chordate that thrives under conditions of anthropogenic climate change. The B. schlosseri expressed proteome contains unusually high levels of proteins adducted with 4-hydroxy-2-nonenal (HNE). HNE represents a prominent posttranslational modification resulting from oxidative stress. Prior to this study, which identified 1052 HNE adducted proteins in B. schlosseri by LCMS, HNE protein modification has not been determined in any marine species. Adducted residues were ascertained for 1849 HNE modifications, 1195 of which had a maximum amino acid localization score. Most HNE modifications were at less reactive lysines (rather than more reactive cysteines). HNE prevalence on most sites was high, suggesting that B. schlosseri experiences and tolerates high intracellular reactive oxygen species levels, resulting in substantial lipid peroxidation. HNE adducted B. schlosseri proteins show enrichment in mitochondrial, proteostasis, and cytoskeletal functions. We propose that redox signaling contributes to regulating energy metabolism, the blastogenic cycle, oxidative burst defenses, and cytoskeleton dynamics in B. schlosseri. DIA-LCMS quantification of 72 HNE-adducted sites across 60 proteins revealed significant population-specific differences. We conclude that the vast amount of HNE protein adduction in this circumpolar tunicate is indicative of high oxidative stress tolerance contributing to its range expansion into diverse environments. SUMMARY: Oxidative stress results from environmental challenges that increase in frequency and severity during the Anthropocene. Oxygen radical attack causes lipid peroxidation, leading to HNE production. Proteome-wide HNE adduction is highly prevalent in Botryllus schlosseri, a widely distributed, highly invasive, and economically important biofouling ascidian, and the first marine species to be analyzed for proteome HNE modification. HNE adduction of specific proteins may physiologically sequester reactive oxygen species, which could enhance fitness and resilience during environmental change.

To reveal local coral species aptness for reef restoration, 30 "framed reef modules" (FRMs) were deployed in a degraded coral reef area at the northern part of Wuzhizhou Island, Hainan Island, South China Sea. Fragments of opportunity from 10 coral species (8 branching, 1 foliose, 1 encrusting) were collected and outplanted on the FRMs. Measurements of growth rates, survival, and physiological indexes were then taken at 30, 120, 210 and 360 days after transplantation. The results showed that Acropora microphthalma, Acropora austera, Hydnophora rigida and Montipora foliosa showed fast growth rates (>2.87 cm(2).month(-1)) and high one-year survival rates (>80 %). Acropora hyacinthus and Montipora digitata, while exhibiting faster growth rates (4.95 +/- 0.31 and 4.85 +/- 0.41 cm(2).month(-1), respectively), revealed lower one-year survival rates (ca. 50 %). Psammocora contigua and Porites cylindrica showed lower growth rates (1.50 +/- 0.14 and 1.96 +/- 0.19 cm(2).month(-1), respectively), yet presented 100 % survival rates. Pocillopora damicornis and Echinopora gemmacea exhibited the lowest growth rates (1.01 +/- 0.14 and 1.73 +/- 0.21 cm(2).month(-1), respectively) and 86.2 % and 93.1 % survivals. There are differences in growth and survival among different types of corals, which are closely related to their physiological characteristics. The biomasses of P. contigua, P. cylindrica, and M. foliosa were the highest, >10 mg.cm(-2), while for the remaining 7 species values were > 8 mg.cm(-2). The highest photosynthesis rates were recorded in P. contigua, P. cylindrica, A. austera, and M. digitata, while the lowest were in P. damicornis and H. rigida. These results demonstrate significant interspecific differences in survival and growth patterns, highlighting the importance of species-specific restoration strategies. The present transplantation method supports restoration approaches that combine different coral species in a single transplantation action.

Coral reefs decline in Mauritius, driven by rising temperatures, sedimentation, and physical disturbance, has rendered passive conservation insufficient. This 27-month study assessed the survival and growth of naturally dislodged but viable coral fragments (corals of opportunity; COOs) left at a sediment-impacted site in Pointe aux Feuilles, as compared to COOs collected and immediately attached in situ to elevated metal frames. COOs of five species were used namely: Acropora selago, Acropora muricata, Acropora Cytherea, Pocillopora damicornis and Millepora alicornis. A controlled field experiment was conducted in which growth was quantified from standardized photographs using ImageJ, while survival and bleaching patterns were statistically analyzed to determine species-specific responses under natural and nursery conditions. Substrate-elevated modules significantly enhanced coral performance: Pocillopora damicornis and Millepora alicornis showed the highest growth (55.8 cm² and 36.2 cm²), while three branching Acropora species exhibited lower survival and greater bleaching. Final bleaching rates were lowest in P. damicornis (0 %) and highest in A. muricata (46.7 %) on nursery modules, while in situ COOs suffered bleaching rates up to 66.7 % and over 25 % dislodgement. Sediment accumulation was consistently higher on natural reefs (Welch’s t = 18.9, p < 0.001), highlighting site exposure as a key stressor. These results show that COOs, when stabilized in elevated, higher-flow environments, support reef recovery without harming donor colonies or donor reefs. Often overlooked, COOs offer a sustainable restoration option when identified early and maintained under favorable conditions.