The specimen, measuring an impressive 2580 millimeters in total length, was caught by a surface tuna gillnet operated from a multiday fishing boat off the western coastal waters of Sri Lanka on 27 October 2021. The fish was landed at Beruwala Fishery Harbor and subsequently preserved in 5% formaldehyde before being deposited in the National Faunal Repository at the Colombo National Museum, Sri Lanka. This single, fresh, complete specimen now represents the first detailed morphological description of R. russellii from Sri Lankan waters.

Oarfishes, belonging to the family Regalecidae, are among the most extraordinary creatures in the ocean. Characterized by an extremely slender, laterally compressed, and very elongated ribbon-like body, they hold the distinction of being the longest bony fish in the world. The family is classified into just two genera, Regalecus and Agrostichthys, with three known species: Agrostichthys parkeri, Regalecus glesne, and Regalecus russellii. These oceanic fishes occur from surface waters to greater depths in temperate and tropical waters, yet they are exceptionally rare in nature, making every confirmed sighting scientifically significant.

The limited number of sightings, incomplete notes on encounters, scarce voucher specimens, and frequent misidentifications have all contributed to inadequate knowledge about the diversity, taxonomy, ecology, and distribution of oarfish species. This scarcity of information makes the Sri Lankan specimen particularly valuable, as it allows researchers to conduct a thorough morphological analysis that can be compared with confirmed records from other ocean basins.

The research team employed rigorous morphological methodologies to document the specimen. Measurements were collected to 1 millimeter precision using calibrated tape and Vernier calipers, while the specimen’s weight was measured to the nearest gram using a digital weighing balance. The fish was radiographed by dividing it into six overlapping sections using a static X-ray machine at the Faculty of Veterinary Medicine and Animal Science, University of Peradeniya. The X-radiograph images of all six sections were then processed to create a complete image, enabling researchers to count vertebrae and examine the dorsal fin ray arrangement.

The morphological examination revealed fascinating details about the specimen. The dorsal fin contained 337 total soft dorsal rays, with two distinctive dorsal crests: the first crest bearing five rays united by fin membranes and the second crest consisting of a single ray free from other rays. The body was long, deeply compressed, and ribbon-like, tapering towards the tail without scales but covered with dermal tubercles with circular bases. These tubercles became more prominent towards the tail end and lower sides of the body. The head was small, measuring just 9.1% of total length, with an almost vertical profile prior to the dorsal fin origin. The mouth was small, vertical, and protractible, with teeth entirely absent.

The coloration of the fresh specimen was equally striking. The body displayed a silvery-grey base with amorphous oblique dark streaks and blotches distributed across the body, most distinct in the first third. The forehead, mouth, preopercle, opercle, and lower margin of the head appeared greyish black. Perhaps most notably, the upper and lower body margins exhibited a crimson red luster, especially in the first half of the body, while the dorsal and ventral fins were entirely dark crimson red. When preserved, the body coloration shifted to yellowish brown with the same dark streaks and blotches.

The morphological characters of the Sri Lankan specimen matched well with key identification features of R. russellii previously reported from the eastern and western Pacific Ocean and the Atlantic Ocean. This consistency across ocean basins provides important confirmation of the species’ identity and extends its known range into the northern tropical Indian Ocean. The vertebral count of 114 and the gill raker arrangement on the first gill arch, numbering 55 in total with 12 on the upper portion and 43 on the lower, further supported the identification.

The significance of this record extends beyond simple range extension. Regalecus russellii was originally described as Gymnetrus russelii by Cuvier in 1816 from Vizagapatam, now Visakhapatnam, on the eastern coast of India in the Bay of Bengal. The first documentation of a Regalecus species from the Indian Ocean actually dates back to 1788, when Patrick Russell recorded a specimen from Visakhapatnam, though that juvenile specimen was not retained after drawing. Despite numerous scattered records of Regalecus from the Indian Ocean over the centuries, only two specimens had been identified to species level as R. russellii prior to this report, and no single specimen from the Indian Ocean has been accepted as a neotype for the species.

The two Regalecus species exhibit contrasting distribution patterns across the world’s oceans. In the Pacific Ocean, numerous records of R. russellii are documented from the North Pacific, while all records of R. glesne are concentrated in the South, with the exception of one R. russellii record from northern New Guinea. In the Atlantic Ocean, R. glesne has been documented exclusively in the North Atlantic and Mediterranean, while both species occur in the South Atlantic. The two species also show distinct habitat preferences related to water temperature and ocean currents: R. glesne is typically associated with colder waters, whereas R. russellii is commonly found in warmer regions. The Sri Lankan record, coming from the warm tropical waters of the northern Indian Ocean, aligns perfectly with these thermal preferences.

Interestingly, the spawning grounds of both Regalecus species occur at the extreme western end of the Indian Ocean, on the southern coast of South Africa, with R. glesne spawning also documented at the eastern end of the Indian Ocean on the coast of Western Australia. According to Roberts, the adults and early life stages of Regalecus found on the south coast of South Africa could be part of populations from the South Atlantic. The presence of a mature specimen in Sri Lankan waters raises intriguing questions about whether resident populations exist in the northern Indian Ocean or whether individuals occasionally venture far from known population centers.

The association of Regalecus with upwelling zones is particularly noteworthy. These areas feature surface cold water rich in biological productivity, which can serve as feeding grounds with optimum environmental conditions close to surface waters. The present specimen was found in shallow waters off the western coast of Sri Lanka, an area that overlaps with the coastal upwelling region. Numerous mesopelagic fish species, including members of the family Trachipteridae, have been recorded from the western and southern coastal upwelling zones of Sri Lankan waters during the summer monsoon, suggesting these productive areas attract deep-water species towards the surface.

Most records of Regalecus species are accidentally caught in fishing gear during operations and are often discarded without proper documentation. There have been many reports of oarfish landings by fishermen at various sites along the Indian and Sri Lankan coastal waters, but many of these accounts have not been published in peer-reviewed publications or made accessible to the scientific community. Advancing technology, along with the widespread accessibility of cameras and smartphone cameras, has significantly improved the frequency of recordings in recent years within the Indian Ocean region.

Citizen science programs and knowledge dissemination platforms, including social media, apps, and websites, play a crucial role in enhancing public awareness and encouraging the recording of rare or poorly known marine species. Such programs are essential to understanding marine biodiversity and supporting conservation strategies, particularly in understudied tropical waters. The Sri Lankan oarfish record demonstrates how collaboration between fishermen, researchers, and natural history institutions can yield significant scientific discoveries, even in an era of advanced marine research technology.

Seasonal patterns in Regalecus strandings and accidental catch records have been observed in certain areas, such as the Gulf of Mexico coast of Florida, though these events have not been clearly linked to environmental factors. In contrast, stranding and accidental catch reports from Australian waters have shown a clear association with storm events. The few records of Regalecus from the Indian Ocean remain inadequate to observe any patterns of stranding or accidental catch, but the species recorded are closely associated with upwelling zones of the Indian Ocean. As more records accumulate from this vast and understudied region, researchers may begin to identify environmental drivers behind these encounters.

This first confirmed record of Regalecus russellii from Sri Lankan waters represents a milestone in Indian Ocean marine biology. The detailed morphological description, complete with radiographic analysis and comprehensive meristic data, provides a reference point for future identifications in the region. The specimen, now safely preserved in the National Faunal Repository at the Colombo National Museum, stands as a testament to the scientific value of even a single well-documented specimen. As technology continues to advance and more researchers and citizens turn their attention to the ocean’s mysteries, the veil surrounding these magnificent ribbon-like giants of the deep may finally begin to lift, revealing insights into their biology, distribution, and the ecological roles they play in the vast tropical Indian Ocean.

Subject of Research: First record of oarfish, Regalecus russellii (Actinopterygii, Lampriformes, Regalecidae), from Sri Lankan waters, Indian Ocean

Article Title: First record of oarfish, Regalecus russellii ( Actinopterygii , Lampriformes , Regalecidae ), from Sri Lankan waters, Indian Ocean

Article References: Rathnasuriya, M. I. G., & Hapuarachchi, T. H. I. S. (2025). First record of oarfish, Regalecus russellii (Actinopterygii, Lampriformes, Regalecidae), from Sri Lankan waters, Indian Ocean. Acta Ichthyologica et Piscatoria, 55, 145-150. https://doi.org/10.3897/aiep.55.148496

Image Credits: AI Generated

DOI: 10.3897/aiep.55.148496

Keywords: oarfish, Regalecus russellii, Sri Lanka, Indian Ocean, marine biology, deep sea, rare species, fish taxonomy, upwelling zones, marine biodiversity, First, record

The original project was designed to assess the diversity of xylobiontic beetles as bioindicators of ecological integrity in three forest reserves: Weid, Seerenwald, and Amden, all located in the Canton of St.Gallen. These reserves are part of Switzerland’s ambitious plan to protect 10 percent of its forest area by 2030, with management focused on natural development without forestry intervention. Currently, 7.3 percent of the country’s total forest is already integrated into such reserves. Five different trap types were deployed across the sites: polytraps and tree crown traps (both flight interception traps), turpentine traps, beer traps, and glue rings. All traps were positioned near large stocks of deadwood, and the comprehensive sampling resulted in more than 600 different xylobiontic beetle species, including rare old-growth relict species and first records for Switzerland.

But alongside the beetles, the traps captured a vast array of non-target organisms. After sorting all Coleoptera from the bycatch, the remaining samples were preserved in an alcohol-glycerol mixture and sent to the Natural History Museum of St.Gallen, where they remained untouched for approximately eight years. In 2025, researchers re-examined these samples, specifically sorting for two taxonomic groups of fundamental ecological importance: Arachnida (spiders and harvestmen) and Hymenoptera (bees, parasitic wasps, and related groups). These organisms serve as predators, parasitoids, or pollinators, making them critical components of forest ecosystems.

The results were striking. From 1,105 bycatch individuals, the team identified 254 taxonomic units, including 55 species of Arachnida (51 spiders and four harvestmen) and 199 species of Hymenoptera. The Hymenoptera encompassed 67 bee species, four cuckoo wasp species, 85 ichneumonid wasp species, eight spider wasp species, six potter wasp species, and 29 sphecid wasp species. Most specimens were recorded in flight interception traps positioned near the herb layer or in the tree canopy, with polytraps proving especially productive for nearly all groups analysed.

Among the most remarkable discoveries was the first record for Switzerland of the ichneumonid wasp Casinaria dubia, found in the forest reserve Weid. This solitary koinobiont endoparasitoid of Lepidoptera is known from Austria, France, Germany, Hungary, Japan, and the United Kingdom, but had never been documented in Switzerland before. The discovery is not entirely surprising, as researchers estimate that over 1,200 species of the Ichneumonidae family may still be unknown in the country. More sensational, however, was the rediscovery of another ichneumonid species, Bioblapsis polita, which had not been observed in Switzerland since 1958 — a gap of 67 years. The team found 76 specimens of this Western Palaearctic species, which is a known koinobiont endoparasitoid of hoverfly larvae, particularly those of the genus Ferdinandea, whose larvae are saproxylic in the sap of over-mature trees, mostly oaks. Given that the species was previously represented in Swiss collections by only a single female, the abundance of specimens found suggests these forest reserves provide ideal habitat for its hoverfly hosts.

The spider Episinus maculipes, a rare European species of the family Theridiidae, was also recorded for the first time in eastern Switzerland. Prior to this finding, the species was known from only two other Swiss locations: Ticino around 1997 and Basel Land in 2003. The new record was accompanied by three additional first records for eastern Switzerland: the spiders Dictyna pusilla, Entelecara acuminata, and Clubiona caerulescens. Even though spiders are more thoroughly studied than some other groups in the bycatch, the findings show that the distribution of many species in Switzerland remains incompletely sampled.

Three bee species listed as near threatened in Switzerland were also identified: Osmia uncinata, which prefers sparse, pine-dominated forests, found in Weid; Megachile ligniseca, which favours moist forests and forest edges, found in Amden; and Andrena combinata, which prefers dry, warm, and sunny locations, found in Seerenwald. These records underscore the conservation value of the forest reserves and the importance of maintaining diverse forest structures for threatened pollinators.

The study also revealed important patterns in how different trap types contribute to bycatch diversity. Polytraps and tree crown traps captured the vast majority of specimens, while beer and turpentine traps contributed only a minor fraction. The researchers suggest that the broad collection range of flight interception traps, combined with the overlapping ecological niches of the identified groups and xylobiontic beetles — many of which feed on pollen and nectar as adults — explains this pattern. The yellow bands on polytraps, which mimic flowers, appear particularly attractive to bees and ichneumonid wasps. Based on these findings, the additional effort of deploying beer traps and turpentine traps may not be justified in surveys targeting the groups analysed here.

However, the researchers caution that preservation conditions can significantly affect the retrospective value of bycatch samples. The determination of harvestmen proved extremely difficult because important identification features were disrupted by the glycerol in the preservation mixture. Similarly, colour patterns on some sphecid wasps had faded over time. While morphological evaluation was still feasible, molecular analysis was significantly hampered by poor preservation, as preliminary DNA barcoding tests showed insufficient DNA quality and quantity. The team recommends that handling and curation of bycatch should be considered in accordance with group-specific requirements and incorporated into future project planning, including optimal preservation agents and careful data recording.

The findings carry broad implications for biodiversity research worldwide. Many monitoring projects have collected, or will collect, large quantities of bycatch material that often remains unexamined or is simply discarded. The current shortage of taxonomic specialists, combined with the time and cost required to sort and identify bycatch, means that vast portions of this material sit untouched in storage, sometimes for decades. Yet, as this study demonstrates, well-curated bycatch samples can provide precious insights into the ecology and distribution of rare taxa, even years after collection. With increasingly fast and cost-effective molecular methods such as DNA metabarcoding, high-resolution imaging, and AI-assisted identification, the potential value of existing collections is greater than ever. The researchers recommend prioritizing the curation of bycatch samples, collaborating with taxonomic experts, and applying molecular methods to unlock the scientific gold hidden within these overlooked specimens.

Subject of Research: Biodiversity

Article Title: Reclaiming the Unwanted: Mining Scientific Gold from multi-trap bycatch

Article References: Urfer, K., König, N., Kranz-Baltensperger, Y., Klopfstein, S., Niehuis, O., von Virag, A., & Sann, M. (2025). Reclaiming the Unwanted: Mining Scientific Gold from multi-trap bycatch. Alpine Entomology, 9, 91-102. https://doi.org/10.3897/alpento.9.168169

Image Credits: AI Generated

DOI: 10.3897/alpento.9.168169

Keywords: bycatch, biodiversity, entomology, Switzerland, forest reserves, rare species, conservation, Reclaiming, Unwanted, Mining, Scientific, Gold

The research team, led by Xiang-peng Liang of Xinyang Agriculture and Forestry University together with colleagues from Dongzhai National Nature Reserve, established 36 permanent plots, each measuring 20 by 20 meters, across the counties of Xixia, Neixiang, and Xichuan. Within every plot they measured every woody stem with a diameter at breast height of at least 3 centimeters, recording species identity, trunk diameter, and height. The decision to exclude smaller stems was deliberate: young shoots in these forests are often multiple branches of the same clonal individual, and counting them would have inflated the numbers and obscured the true structural patterns of the stand.

The tally came to 2,210 woody individuals belonging to 39 species, 33 genera, and 26 families. Oak and pine led the cast: Quercus variabilis, the Chinese cork oak, and Pinus massoniana, Masson’s pine, emerged as the two most important species by a wide margin, followed by Pistacia chinensis, Albizia kalkora, and Platycarya strobilacea. The flora is characteristic of a transitional zone between the northern subtropical and warm-temperate climatic regions, with temperate deciduous species making up 34 of the 39 recorded species. Families such as Fagaceae, Pinaceae, Juglandaceae, Cupressaceae, and Fabaceae contributed the largest numbers of individuals, reflecting the mixed broadleaf-conifer character of these central Chinese foothills.

What makes the study distinctive is its explicit partitioning of the community into common, occasional, and rare species. Using local density thresholds, the researchers classified species with more than 10 individuals per hectare as common, those between 1 and 10 as occasional, and those at or below 1 individual per hectare as rare. The result was striking: of the 39 species, 11 were common, 18 occasional, and 10 rare. Yet the 11 common species accounted for 2,117 of the 2,210 individuals, a staggering 95.8 percent of all stems. Occasional and rare species, despite making up nearly three-quarters of the species pool, contributed only a trickle of individuals. The rank-abundance curve for the community was steep, a classic signature of dominance by a handful of species.

Importance value, a composite metric combining relative abundance, relative frequency, and relative basal area, told the same story in sharper relief. Quercus variabilis alone scored an importance value of 55.55 percent, with a relative abundance of 76.61 percent and a relative basal area of 66.39 percent, meaning that roughly two-thirds of the total cross-sectional wood area in these plots belongs to a single oak species. The importance values of all common species together summed to 76.5 percent of the community total. At the other extreme, the top five rare species each registered an importance value of just 0.25 percent, with equal relative abundance and relative frequency, a mathematical fingerprint of species represented by only one or two scattered individuals.

The structural analysis revealed what the researchers describe as a conspicuous growth-stage bottleneck for rare species. Common species dominated every diameter and height class, with peak abundance in diameter class II, trees between 5 and 10 centimeters in trunk diameter, corresponding to heights of 6 to 9 meters. Rare species, by contrast, were largely confined to that same intermediate diameter class and the middle height classes, with a complete absence of individuals in the largest size class of 30 centimeters or more and none in the upper height strata above 12 meters. The consistency between the upper limits of their diameter and height distributions suggests that rare species face dual constraints in vertical space: they cannot reach the canopy through either girth or growth.

The authors interpret this pattern not as simple competitive suppression by shading from the dominant canopy, but as evidence that these rare taxa behave as gap-dependent or mid-successional species. Under a closed canopy, such species may persist as static remnants, maintaining a limited number of intermediate-sized individuals without producing new recruits or advancing into the upper strata. The complete absence of rare species from both the smallest and largest size classes supports this reading. Meanwhile, the relatively low abundance of common species in the smallest diameter class may reflect pressure from a dense and diverse understory shrub layer, which competes with saplings for the light and resources needed during early regeneration.

Perhaps the most unexpected finding concerns plant sex. Among the 2,210 individuals, monoecious plants, those bearing separate male and female flowers on the same individual, dominated overwhelmingly, accounting for 1,972 stems or 89.2 percent of the total. Dioecious species, with male and female flowers on separate plants, contributed 142 individuals, and hermaphroditic species just 16, though hermaphroditic and monoecious taxa each comprised 13 of the 39 species. The distribution across abundance classes was anything but random: common species were predominantly monoecious, occasional species showed a relative surplus of dioecious individuals, and rare species were characterized chiefly by hermaphroditic sexual systems.

The researchers argue that these sexual system patterns reflect divergent reproductive strategies shaped by population density. Monoecy, with its capacity for self-compatibility, allows rapid population establishment during early colonization and confers advantages under intense resource competition, helping common species build and maintain large populations. For rare species, whose small populations and low densities make cross-pollination between distinct individuals risky, hermaphroditism functions as a bet-hedging strategy: when conspecific pollen is scarce or pollinators are absent, self-compatibility offers reproductive assurance. This advantage, however, may be offset by limited understory light beneath the closed canopy, which suppresses photosynthesis and reproductive output, compounding the regeneration difficulties that already constrain these sparse populations.

The conservation implications reach well beyond academic interest. Rare species often occupy unique positions in community functional space, contributing disproportionately to functional diversity relative to their numbers, and previous work has shown that they tend to have lower functional redundancy and higher functional vulnerability than common species. Their loss, the study’s authors note, is therefore more likely to erode ecosystem functions and resilience, a concern of particular weight in a water source region where forest communities underpin water quality and regional environmental stability. The team recommends that management in the intake area prioritize the maintenance of canopy heterogeneity and the retention of rare species’ microhabitats, and they call for functional trait measurements and long-term demographic monitoring to clarify how plant sexual systems, community assembly, and ecosystem services are linked in this strategically vital landscape. Occasional species, which form the largest share of the local species pool yet remain numerically minor, may represent a reservoir of opportunistic taxa whose expansion depends on future disturbance events, a hypothesis that only sustained observation can test.

Subject of Research: Species composition and sexual systems of common and rare woody plants in the intake area of the South-to-North Water Diversion Project

Article Title: Contrasting species composition between common and rare woody species in the intake area of the South-to-North Water Diversion Project

Article References: Liang, X.-P., Yu, J.-L., Peng, C., & Zhu, J. (2026). Contrasting species composition between common and rare woody species in the intake area of the South-to-North Water Diversion Project. Frontiers in Ecology and Evolution, 14, Article 1971552. https://doi.org/10.3389/fevo.2026.1971552

Image Credits: AI Generated

DOI: 10.3389/fevo.2026.1971552

Keywords: forest ecology, rare species, common species, South-to-North Water Diversion Project, species composition, sexual systems, monoecy, hermaphroditism, biodiversity conservation, Nanyang, Henan, community assembly

The coastal margin is ecologically distinctive because it is governed by processes that rarely operate together elsewhere in the reserve. Sand movement, salt accumulation, groundwater levels, temporary flooding, wave exposure, wind action, and local human use combine to create a discontinuous mosaic of plant communities rather than a uniform vegetation belt. Open beach vegetation, embryonic dunes, fixed dunes, saline depressions, humid interdunes, and coastal shrubs can occur in close contact, often changing over only a few tens of meters. This coupling of vegetation, sediment transport, and disturbance is a defining feature of coastal-dune systems internationally, and it is particularly important for plants with narrow ecological requirements. Some species colonise bare or weakly stabilised sand; others are restricted to saline or brackish depressions, dune edges, or relatively undisturbed backshore habitats. Several of these taxa have small populations, fragmented distributions, or conservation statuses that warrant attention under Romanian red-list sources.

The floristic total of 661 taxa confirms the coastal area’s botanical importance and spans several ecological groups: psammophilous plants of open sand, halophytes of salt-affected soils, hygrophilous species of wet depressions, grassland and shrub species, and ruderal elements occurring locally under human influence. Poaceae was the richest family in the coastal inventory, with 101 taxa representing 15.3 percent of the total flora, followed by Asteraceae with 86 taxa (13.0 percent) and Chenopodiaceae with 53 taxa (8.0 percent). Together, these three families accounted for 240 taxa, or 36.3 percent of the recorded vascular flora. Other well-represented families included Brassicaceae with 35 taxa, Caryophyllaceae with 33, Fabaceae and Cyperaceae with 32 each, and Lamiaceae with 24. The prominence of grasses, chenopods, sedges, brassicas, and pinks is consistent with the extensive representation of grasslands, dunes, saline surfaces, wet depressions, and pioneer habitats within the coastal mosaic.

The 47 vegetation associations recorded in the dataset indicate that coastal vegetation is not a simple linear sequence from the sea inland. Annual pioneer communities develop on open beaches and freshly disturbed sand; dune-building communities occur where sand begins to accumulate; perennial dune grasslands occupy more stable sites; saline depressions support halophilous assemblages; and locally developed shrubs mark sectors with greater substrate stability or lagoonal influence. Beach and strandline vegetation form the first living cover above the active shore, often sparse and seasonal yet ecologically important because they initiate colonisation of open sand and may trap organic material and sediment. Embryonic dunes and mobile dune communities form where sand accumulation stabilises, and their plant species tolerate shifting sand, wind exposure, and low nutrient availability. By capturing sand and reducing substrate mobility, they create conditions for later successional stages, and damage to these communities can disrupt dune formation and increase the shoreline’s vulnerability.

Wet interdune depressions and saline flats add further ecological complexity. Temporary flooding, groundwater mineralisation, evaporation, and microrelief shape these sites, which can support halophytes, hygrophilous species, and mixed communities that differ markedly from the adjacent dry dunes. Coastal shrubs and Tamarix-related vegetation enhance habitat structure in protected sectors or lagoon-facing positions. The most valuable sectors are those where natural beach dynamics, dune development, and saline or wet depressions coexist, creating conditions for many specialised species. Conversely, sectors subject to repeated mechanical disturbance, trampling, or overgrazing tend to lose this fine-scale structure and become floristically simplified.

The conservation analysis identified 58 taxa with Romanian Red List status among the 661 recorded taxa, meaning 603 taxa, or 91.2 percent, carried no conservation category in the sources consulted. The remaining 58 taxa included 43 classified as rare, nine as vulnerable/rare, three as endangered/rare, two as endangered, and one as vulnerable. These categories reflect historical national conservation sources and should not be interpreted as a new assessment under current IUCN criteria, but they identify a substantial group requiring periodic field verification and population monitoring. Among the flagship species are Crambe maritima, a recognisable coastal plant of natural beaches and dune margins; Eryngium maritimum, a typical dune species with ornamental value; and Stachys maritima, one of the rarest sandy-habitat specialists recorded, found only at Portița and Corbu with a very small population.

Several detailed species accounts illustrate the range of habitats and conservation challenges along the coast. Argusia sibirica, considered critically endangered in the Romanian Red Book, is a characteristic maritime species linked to the Black Sea coast, central Russia, northern Anatolia, and a broader Eurasian range extending eastward to Japan. The project dataset confirmed it at all previously known Romanian coastal areas as well as on Musura Island and between Perișor and Periteașca. Centaurea pontica, one of the most important endemic elements of the Romanian coastal flora, was confirmed in the Sulina urban area but not recently found at Ciotic, where renewed field verification is required. Asparagus brachyphyllus, treated as critically endangered in the Romanian Red Book, was not detected at its historical sites of Istria and Grindul Chituc, but a few individuals were identified in the Periteașca-Perișor sector, making this one of the most important field confirmations in the dataset.

Convolvulus persicus, a critically endangered Ponto-Caspian coastal plant, was confirmed at Sfântu Gheorghe, Sulina, north of Sfântu Gheorghe, Perișor, and Sacalin Island, but the notes indicate that one monitored site had already lost the species and that Perișor hosted only a few individuals, confirming the highly uneven and vulnerable distribution of the species along the coast. Dianthus bessarabicus, a rare and subendemic psammophilous species, was field-confirmed in the Sfântu Gheorghe, Grindul Sărăturile, Perișor, Periteașca, and Sulina sectors. Limonium bellidifolium, a rare halophilous species treated as critically endangered in the Romanian Red Book, was confirmed at Sfântu Gheorghe, Sacalin Island, Grindul Lupilor, Sulina, and Grindul Sărăturile, usually in small numbers, with recent taxonomic discussions treating Danube Delta populations under Limonium bellidifolium subsp. danubiale.

The supplementary spatial analysis summarised 1,243 occurrence records representing 111 species profiles across 134 source grid squares, of which 841 records, or 67.7 percent, intersected at least one mapped Natura 2000 habitat at the grid-square level. Species richness by habitat was highest for habitat 1410, with 96 profiles representing 86.5 percent of all profiles, and habitat 1310, with 90 profiles representing 81.1 percent, followed by 2110, 2160, 1210, and 2130. The strongest compositional overlap occurred between habitats 1310 and 1410, with 83 shared profiles and a Jaccard coefficient of 0.806 and a Sørensen coefficient of 0.892, followed by 2110 and 2160 with 60 shared profiles and a Jaccard coefficient of 0.750. This overlap indicates conservation interfaces within a fine-scale mosaic of beaches, dunes, saline surfaces, wet depressions, grasslands, and shrub communities, rather than interchangeable habitat units. Qualitative population dynamics were reported as stable for 52 profiles, decreasing for 50, increasing for six, and unclear for three, showing that high regional richness does not necessarily mean that local populations are secure.

Keyword screening of the species accounts identified grazing or overgrazing in 98 profiles, or 88.3 percent, tourism or development in 50 profiles, or 45.0 percent, beach cleaning or mechanical disturbance in 46 profiles, or 41.4 percent, restricted or reduced habitat area in 44 profiles, or 39.6 percent, and low reproductive or dispersal capacity in 36 profiles, or 32.4 percent. These pressure frequencies are non-exclusive summaries of the species accounts, not estimates derived from a controlled impact-sampling design. Mechanical beach cleaning is especially relevant because it can remove seedlings, seeds, and organic material needed for pioneer vegetation to develop, and while cleaning may be necessary in recreational sectors, it should be selective and should avoid natural beaches with rare species or embryonic dune vegetation. Grazing also requires careful interpretation: moderate grazing may keep some grassland habitats open, but excessive grazing leads to compaction, nutrient enrichment, ruderalization, and the loss of sensitive plants. The most vulnerable situations occur where small, rare-plant populations coincide with accessible beaches, narrow dunes, or fragmented habitats, where even an apparently minor local disturbance can produce disproportionate conservation effects.

The study’s authors stress that the results represent a regional historical baseline rather than standardised estimates of occupancy or trend, because survey effort was heterogeneous across years and sectors and habitat links were assigned at grid-square level. The descriptive design supports identifying spatial patterns and management hypotheses but does not demonstrate causal relationships between pressures and vegetation change, and contemporary resurveys using a documented, repeatable design are needed to test persistence, trend, and management effectiveness. Nevertheless, the synthesis establishes an essential benchmark for future conservation action. The first management priority is to update the floristic and habitat inventory periodically, with repeated mapping focused on rare-species locations, embryonic dune sectors, saline depressions, wet interdunes, and heavily visited beaches. The second priority is microhabitat protection, since rare plants often depend on small-scale local conditions rather than large continuous habitat blocks, and a small dune ridge, a moist hollow, a salt-affected patch, or an undisturbed upper beach may be critical for a local population.

The third priority is better visitor management, because natural beaches with vegetation may look less clean than mechanically maintained recreational beaches but are far more valuable ecologically, and information panels, guided routes, and communication with local tourism operators can reduce accidental damage. The fourth priority is combining in situ and ex situ conservation, including protecting known populations, avoiding destructive interventions, maintaining habitat processes, seed collection, storage in germplasm banks, and cultivation in botanical gardens, especially for taxa with very small or declining populations. The central result is that conservation value is concentrated not only in individual rare-species locations but also at interfaces among habitat types, and management that treats each mapped habitat polygon in isolation may overlook the short environmental gradients, transitional zones, and disturbance regimes that permit specialised taxa to persist. Future action should combine repeatable resurveys, protection of rare-species microhabitats, maintenance of natural sedimentary and hydrological processes, and differentiated control of beach cleaning, vehicles, tourism, and grazing, with the dataset serving as a benchmark against which future persistence, redistribution, and management effectiveness can be tested.

Subject of Research: Coastal vascular plant diversity, vegetation mosaics, and conservation priorities of the Danube Delta Biosphere Reserve's Black Sea margin

Article Title: Coastal vascular plant diversity of the Danube Delta Biosphere Reserve: Rare plants, vegetation mosaics, and conservation priorities

Article References: Doroftei, M., Covaliov, S., Chirilă, S. D., & Tudose, F. (2026). Coastal vascular plant diversity of the Danube Delta Biosphere Reserve: Rare plants, vegetation mosaics, and conservation priorities. Scientific Annals of the Danube Delta Institute, 31, 25-46. https://doi.org/10.3897/saddi.31.206519

Image Credits: AI Generated

DOI: 10.3897/saddi.31.206519

Keywords: Danube Delta, biodiversity, coastal ecology, plant conservation, Natura 2000, rare species, Black Sea, habitat mosaic, Coastal, vascular, plant, diversity

Coastal dunes are among the most threatened ecosystems on Earth, squeezed between rising seas, intensifying erosion, tourism, and urban expansion. What makes them ecologically remarkable is their strict spatial order. Moving inland from the waterline, plants sort themselves into zones: an unfixed zone of shifting sand nearest the shore, a semi-fixed zone behind it, and finally a fixed zone of stabilized dune where the most sensitive species live. Because each zone depends on precise gradients of salt spray, sand movement, wind, and soil conditions, the fixed zone is the first casualty of development and the hardest to restore. Its loss ripples through the entire system, taking rare plants with it.

The research team, led by Yuki Yamanaka, Keiko Nagashima, and Yasutaka Nakata, focused on Juniperus conferta, a low-growing shrubby juniper that serves as the classic indicator species of the fixed dune zone across Hokkaido, Honshu, Shikoku, Kyushu, and Sakhalin. The species is listed as rare in ten Japanese prefectures and grows alongside threatened plants such as Viola grayi and Veronica ornata. The logic of the study is elegant: if you can map precisely where J. conferta survives and characterize the microtopographic conditions it requires, you gain a practical yardstick for identifying the remaining strongholds of the fixed zone, and by extension, the habitats of the rare species that depend on it.

The historical half of the analysis is sobering. Using an 1898 topographic map, United States military aerial photographs from 1947, and a 2009 aerial survey, the researchers built land-cover maps for three time slices and tracked what happened to the original dune surface. In 1898, sand dunes covered roughly 192 hectares, the largest dune area in Kyoto Prefecture. By 1947 that figure had fallen to about 106 hectares, and by 2009 only about 33 hectares remained, a decline of more than 80 percent in little over a century. Afforestation, which began in the Edo period to control drifting sand and accelerated during Japan’s postwar economic boom, accounted for roughly half of the original dune area by 2009, while urbanization and paddy fields consumed much of the rest.

The losses were strikingly uneven across the dune’s four sectors. In the west, the dune shrank to about a fifth of its original extent as forests and town expanded inland. The west-central sector suffered the steepest transformation, with approximately 80 percent of its 1898 dunes replaced by conifer plantations. The east fared worst of all: around 90 percent of its original sand dunes had been converted to other land uses by 2009, with wastelands mapped in 1947 largely becoming urban areas. Only the east-central sector, a rocky coastline where steep cliffs limited development, retained nearly all of its original sandy habitat, a quirk of geology that would prove decisive for the study’s rarest plants.

To capture the present-day physical template of the dune, the team deployed a drone equipped with LiDAR, a laser instrument that fires pulses at the ground and records the returning light to build a dense three-dimensional point cloud. From this they derived a digital terrain model at one-meter resolution, matching the scale of their vegetation quadrats, along with slope angle, curvature, distance from the shoreline, and elevation. Crucially, they also computed the difference between the 2024 drone-derived terrain model and a 2009 airborne LiDAR dataset, producing a map of elevation change across fifteen years. After correcting a systematic vertical offset of about 3.46 meters in the drone data using fifty stable reference points, they established a conservative detection limit of roughly 0.12 meters, meaning only elevation changes beyond that threshold were treated as real.

On the ground, the researchers surveyed 165 one-square-meter quadrats distributed randomly across the four sectors and classified the vegetation into seven communities using the Two-Way Indicator Species Analysis, a standard clustering technique for presence-absence data. The J. conferta community split into two ecologically distinct groups: one on sandy beach coasts and one on rocky coasts. In total, the surveys recorded 30 coastal dune species and 40 non-coastal species, including eight listed in the Kyoto Prefecture Red Data Book. The east-central rocky sector stood out with the highest species richness at 47 species and five rare species, while the heavily modified west sector contained no rare species at all and a relatively high proportion of alien plants.

The statistical core of the study used generalized linear models to ask which topographic variables best predict where each J. conferta community occurs. For the sandy-beach community, two factors emerged consistently: the probability of occurrence rose with increasing distance from the shoreline and with greater elevation change since 2009. This makes intuitive sense. The community’s stronghold in the west-central sector is the one place where the beach is wide enough, over 100 meters, for the full sequence of dune zones to develop, allowing pioneer communities to trap drifting sand and build the stable backshore that dwarf juniper shrubland requires. The rocky-coast community told a different story: models pointed toward shorter distances from the shoreline and higher elevation, but a sensitivity analysis accounting for spatial autocorrelation in the data weakened these effects, suggesting the pattern may reflect broader geomorphic processes, such as a history of coastal erosion, rather than simple topographic rules.

Bringing the two lines of evidence together, the study delivers a sector-by-sector diagnosis. The west-central area, despite pine plantations, still supports functioning zonation and a resident J. conferta community, though afforestation has opened the door to invasive species. The east-central rocky coast harbors the greatest concentration of rare plants, including Viola grayi and Veronica ornata growing symbiotically with the juniper, but it is also the sector showing net elevation loss, a signature of active erosion. Because plant roots stabilize rocky slopes, the researchers warn that erosion there could accelerate, leaving the rare fixed-zone communities perched precariously at the cliff edge. The west and east sectors have effectively lost their fixed zones altogether, one to plantations and alien invasions, the other to direct human modification of the dune surface.

The authors are careful about the limits of their framework. Soil salinity, moisture, nutrients, and grain size, all known drivers of dune vegetation, were not directly measured, so the model coefficients describe associations with topography rather than isolated causes. The historical and LiDAR analyses address different time scales and should be read as complementary rather than causally linked, and the findings from a single Sea of Japan dune may not transfer to coasts with different tides, winds, and climates. Even so, the message is powerful and portable: a single well-chosen indicator species, read through the lens of drone-borne laser scanning and archival maps, can pinpoint which parts of a degraded landscape still hold conservation value and which restoration efforts are most urgent. As coastal dunes continue to retreat worldwide under the combined pressure of stabilization plantings, urban growth, and tourism, that kind of quantitative, repeatable diagnosis may be the difference between documenting an extinction and preventing one.

Subject of Research: Indicator-based assessment of coastal dune ecosystem degradation using historical land-cover change and UAV-LiDAR microtopography

Article Title: Indicator-based assessment of coastal dune ecosystem degradation using historical land-cover change and UAV-LiDAR microtopography

Article References: Yamanaka, Y., Nagashima, K., & Nakata, Y. (2026). Indicator-based assessment of coastal dune ecosystem degradation using historical land-cover change and UAV-LiDAR microtopography. Environmental and Sustainability Indicators, 32, Article 101548. https://doi.org/10.1016/j.indic.2026.101548

Image Credits: AI Generated

DOI: 10.1016/j.indic.2026.101548

Keywords: coastal dunes, Juniperus conferta, UAV-LiDAR, land-cover change, ecosystem degradation, vegetation zonation, Kumihama Dune, rare species, digital terrain model, coastal erosion, conservation indicators, Japan