Distribution Limit Research Articles

Optimizing Early Growth of Laminaria hyperborea in Controlled Settings: A Pathway to Improved Restoration Efforts

Laminaria hyperborea, a key species in marine forest ecosystems, is experiencing pressure at its southern distribution limit in northern Portugal due to climate change and human-induced stressors. The ongoing degradation of marine forests highlights the need for effective restoration strategies to protect biodiversity and maintain the essential services provided by these habitats. Cultivation of juvenile kelps in laboratory settings is a common approach shared across multiple strategies aimed at supporting reforestation efforts; however, the specific cultivation process for L. hyperborea remains largely underexplored. In this study, we tested two seeding densities to optimize the production of L. hyperborea recruits for reforestation initiatives. We assessed the effects of seeding density on juvenile development by measuring both area coverage and length. Our findings revealed that higher seeding density initially promoted greater area coverage (e.g., 8.69 ± 0.38 cm2 vs. 3.35 ± 0.27 cm2) but reduced the length of individual recruits over time (e.g., 0.26 ± 0.0026 cm vs. 0.39 ± 0.003 cm at T3). This suggests that increased competition for resources at high densities limits individual growth. In contrast, lower densities produced larger, more robust individuals (e.g., 0.50 ± 0.004 cm vs. 0.262 ± 0.003 cm at T4), which may enhance post-transplantation survival in challenging environmental conditions. This suggests that utilizing lower seeding densities may improve individual growth while decreasing overall resource use and maintenance needs, promoting a more sustainable cultivation process and minimizing impacts on donor populations. However, further research is essential to refine the cultivation protocols and fully understand the variables influencing juvenile kelp development. Improving all phases of the restoration process, from laboratory cultivation to field deployment, will be critical for reducing costs, streamlining logistics, and ensuring the scalability of future kelp restoration efforts.

Influence of Light Intensity and Temperature on the Development of Early Life Stages of Ascophyllum nodosum (Phaeophyceae)

Ascophyllum nodosum is an ecologically and economically important species forming marine forests in temperate regions. In Europe, this brown seaweed reaches its southern distribution limit in the north of Portugal, where populations are under climatic pressure. Conservation and restoration actions are essential to preserve the important ecological roles of these populations, including biodiversity enhancement. In this study, we assessed the effect of temperature and light on the development of the early life stages of A. nodosum, from gamete germination and rhizoid development to germling growth, in order to support the establishment of nursery protocols for producing seedlings that can be used in reforestation actions. We found that for this population, temperature around 12 °C and low-light conditions (40 μmol m−2 s−1) favor gamete germination, rhizoid development, and initial germling growth during the first month, after which higher light supply (>80 μmol m−2 s−1) is needed to sustain further growth stages. The results obtained in this study are relevant for the establishment of nursery methods for A. nodosum and should be complemented by further studies to determine more precisely the light and nutrient requirements to optimize growth in the germlings’ later growth stages.

Using spruces (Picea spp.) for Icelandic afforestation

Afforestation can help address climate change and biodiversity loss. Iceland is a valuable case study to assess afforestation at extreme locations at high latitudes (63–68°N). We used a ~ 23-year dataset of a provenance trial from the Icelandic Forest Service (now Land & Forest Iceland) to determine the best spruce species (Picea spp.) and provenances for afforestation. Sites were either frost-prone or protected (i.e., non-frost-prone) locations, and the latest height and survival data were assessed from six sites (out of nine) in 2018. Provenances were mainly from three spruce species from southwestern Canada and southern Alaska (53–61°N). Sitka spruce (Picea sitchensis) and its hybrids or introgressants with white spruce (P. glauca) survived and grew well in protected areas (≥ 60% and ≥ 275 cm), while white spruce and its hybrids or introgressants with Sitka spruce performed better in frost-prone areas (≥ 55% and ≥ 285 cm, based on combined frost-prone sites). The only provenance suitable for both frost-prone and protected places was a Sitka/Lutz spruce (P. x lutzii) introgressant from Iniskin Bay, Alaska. Additional genetic research would help guide afforestation in harsh areas at high latitudes (a distributional limit of many tree species) and inform forest management about novel environments and sustainable practices. Climate change should also be considered for afforestation efforts.

Studying Chinook salmon in northern river ecosystems through ecological methods and Indigenous, Teslin Tlingit knowledge

In this study, we examined Pacific salmon decline and ecosystem function through Western science and Indigenous, Teslin Tlingit knowledge. We tested relationships of riparian tree growth and nitrogen composition at the limit of Pacific salmon distribution on the Teslin Tlingit Council (TTC) Traditional Territory in Southern Yukon, studied ecosystem roles of salmon and population declines in the area, and the interactions of these processes. Within sites, tree growth was positively related to salmon escapement at all salmon-bearing sites and not at the negative (salmon-free) control site. Mean δ15N was significantly higher at salmon-bearing sites compared to the negative control, showing similar patterns to comparable studies. Between sites, mean site tree growth did not show a clear response to salmon. Interviews conducted with Teslin Tlingit knowledge holders revealed measures of a healthy salmon run and large population declines that have negatively impacted local ecosystems (particularly bears, key to delivering salmon nutrients to terrestrial ecosystems) and human wellbeing on the Traditional Territory. Although this study was limited by available sites and data, we demonstrate that the health of salmon and riparian forests on the Traditional Territory are deeply linked, and the importance of considering multiple ways of knowing to improve ecological research.

Agenda-setting for iron deficiency anaemia prevention and control policies in Iran by multiple streams framework

BackgroundAccording to the WHO report and evaluations, Iran has a moderate prevalence of iron deficiency anaemia (IDA). The present study evaluates Iran’s IDA prevention and control policies by analysing the agenda-setting policy using the multiple streams framework (MSF).MethodsThe present study used Kingdon’s MSF model to analyse policies related to IDA in Iran qualitatively. First, the policy documents were reviewed (n = 12), and then in-depth interviews were conducted with key stakeholders (n = 33) using the framework analysis method. MAXQDA version 2020 was used to categorize the data codes of the interviews and extract related themes.ResultsThe main factors of the problem stream were the prevalence of IDA among Iranian pregnant women, children and adolescents and its risk factors in Iran. The policy stream focuses on mounting the staff in health centres, preventing non-communicable diseases and parasites in the health system, and promoting health programs, such as supplementation, education and fortification. The current political stream regarding IDA shows that national and international support can provide the right political atmosphere for this issue. There are challenges and obstacles related to implementing these policies in Iran, including the preference for treatment over prevention in the health sector, the existence of many economic problems and the limitation of distribution and access to health services owing to some unforeseen issues, such as sanctions or the spread of coronavirus disease 2019 (COVID-19).ConclusionsThe topic of IDA prevention policymaking has entered a new phase. Responsible organizations, such as the Ministry of Health, should emphasize more in allocating budgets for preventive programs, and key organizations, such as the WHO, should support low- and middle-income countries to empower them towards important preventive strategies.

The subarctic ancient Lake El'gygytgyn harbours the world's northernmost 'limnostygon community' and reshuffles crangonyctoid systematics (Crustacea, Amphipoda).

The northward distribution limit of groundwater fauna is generally dictated by the extent of glacial ice sheets during the Pleistocene. However, some taxa can be found far above this limit, sometimes on isolated oceanic islands, implying long-term survival in subglacial subterranean refugia. Here we report a peculiar assemblage comprising two new depigmented and blind (stygomorphic) amphipods from the subarctic ancient lake El'gygytgyn (northern Far East): Palearcticarellus hyperboreus sp. nov. and Pseudocrangonyx elgygytgynicus sp. nov. Molecular phylogenetic analyses based on five markers confirm their affinity to Crangonyctidae and Pseudocrangonyctidae, respectively. Fossil-calibrated molecular dating indicates that the ages of both species predate the onset of Pleistocene glaciations by at least an order of magnitude. Although both species are clearly adapted for subterranean life and are related to groundwater taxa, they are only known from the lake waters (5-170-m depth). Despite being nested within Pseudocrangonyctidae, P. elgygytgynicus has an atypical third uropod that preserves a vestigial inner ramus, a trait characteristic to the monotypic sister family Crymostygidae. Given that this character was the main distinguishing feature between the two families, we propose merging Crymostygidae with Pseudocrangonyctidae. Our findings represent the world's northernmost record of stygomorphic amphipods, emphasising their relictual biogeography and the importance of Lake El'gygytgyn as a long-term, high latitude refugium for ancient pre-glacial fauna. ZooBank: urn:lsid:zoobank.org:pub:3A51D1F8-E65D-4A3A-B663-D5C40272E68B.

How citizen science helps to expand the distribution and describe predictors related to a native land snail, while also introducing spatial biases

Abstract Although mollusks represent Earth's second most diverse invertebrate group, their natural history and ecology are still scarcely known. The compilation of non-traditional data, such as those from citizen science, represents an alternative to fill these gaps, particularly on striking land snail species such as Macrocyclis peruvianus. Based on long-term citizen science, we aimed to update and describe some basic ecological aspects, such as the distribution and protected area types used by M. peruvianus. We performed pairwise comparisons to test potential changes in occurrence and occupancy among administrative regions, forest types, and protected area types using chi-squared tests. The citizen scientists were also asked to provide the number of M. peruvianus individuals observed and the tree species that dominated their habitat. Thus, we tested if the number of land snails found by citizen scientists could be related to forest and protected area types using a generalized linear mixed model. We expanded the northern distributional limit, with Nothofagus, evergreen, and mixed forests far the most frequented by M. peruvianus. Parallelly, the occurrence of M. peruvianus in official protected areas (65.73%) was significantly higher than in privately owned areas. Moreover, we did not find associations between forest and protected area types with the number of M. peruvianus recorded. Although citizen science is a helpful method for obtaining novel information regarding the ecology of neglected species such as M. peruvianus, it also introduces spatial and occurrence biases explained by the access and attractiveness of the officially protected areas compared to privately owned patches of native forest.

Cumulative Heat Stress in Fluctuating Temperatures and Implications for the Distribution of Freshwater Fish.

Predicting how rising temperatures will impact different species and communities is imperative and increasingly urgent with ongoing global warming. Here, we describe how thermal-death time curves obtained in the laboratory can be combined with an envelope model to predict the mortality of freshwater fish under field conditions and their distribution limits. We analyze the heat tolerance and distribution of 22 fish species distributed across North America and demonstrate that high temperatures imposed a distribution boundary for 11 of them, employing a null model. Importantly, predicted thermal boundaries closely match the warmest suitable locality of the envelope model. Simulated warming suggests that the distribution of fish species with lower heat tolerances will be disproportionately affected by rising temperatures, and the rate of local extinctions will be higher across fish communities in warmer localities. Ultimately, our analyses illustrate how physiological information can be combined with distribution models to forecast how warming temperatures are expected to impact different species and ecological communities.

Evolutionary Histories of Camellia japonica and Camellia rusticana

ABSTRACTThe genus Camellia is widely distributed, primarily in East Asia. Camellia japonica is located at the northern limit of this genus distribution, and understanding changes in its distribution is crucial for understanding the evolution of plants in this region, as well as their relationship with geological history and climate change. Moreover, the classification of sect. Camellia in Japan has not been clarified. Therefore, this study aims to understand the evolutionary history of the Japanese sect. Camellia. The genetic population structure was analysed using SNP data and MIG‐seq. The relationship between the Japanese sect. Camellia, including the related species in China, was further inferred from the phylogeny generated by RA x ML, SplitsTree and PCA. Population genetic structure was inferred using a Bayesian clustering method (ADMIXTURE). We subsequently employed approximate Bayesian computation, which was further supported by the coalescent simulations (DIYABC, fastsimcoal and Bayesian Skyline Plots) to explore the changes in population, determining which events appropriately explain the phylogeographical signature. Ecological niche modelling was combined with genetic analyses to compare current and past distributions. The analyses consistently showed that C. japonica and C. rusticana are distinct, having diverged from each other during the Middle to Late Miocene period. Furthermore, C. japonica differentiated into four major populations (North, South, Ryukyu‐Taiwan and Continent). The Japanese sect. Camellia underwent speciation during archipelago formation, reflecting its ancient evolutionary history compared with other native Japanese plants. C. rusticana did not diverge from C. japonica in snow‐rich environments during the Quaternary period. Our results suggest that both species have been independent since ancient times and that ancestral populations of C. japonica have persisted in northern regions. Furthermore, the C. japonica population on the continent is hypothesised to have experienced a reverse‐colonisation event from southern Japan during the late Pleistocene glaciation.

Overcoming Local Distribution Limits in the SNC Process in a 10-nm Node DRAM by Applying a Multilayer Contact

Overcoming Local Distribution Limits in the SNC Process in a 10-nm Node DRAM by Applying a Multilayer Contact

Confidence interval estimation for the difference of censored zero-inflated gamma distributions

This paper studies the problem of constructing confidence intervals (CIs) for the difference between coefficients of variation (CV) of two censored zero-inflated gamma distributions. Firstly, we propose a Fiducial inference based method that extends the traditional CI construction method of gamma distribution to the scenario of zero-inflated gamma distributions with censored data. Secondly, we propose a Box-Cox transformation based method, in which not only the sample data needs to be transformed, but also the detection limit of gamma distribution with censored data accordingly. Thirdly, we investigate the Method of Variance Estimate Recovery (MOVER), to combine the previous two gamma distribution CI estimates with three binomial distribution CI estimates, and obtain six combination methods. Furthermore, we conduct Monte Carlo simulations to evaluate the performances of the proposed methods, the results indicate that all CI construction methods achieve satisfactory performances in terms of coverage probability, average length and tail error rates. Finally, we perform real data analysis using 11 years of precipitation data from Zhengzhou and Lhasa.

Shedding Light on the Italian Mesophotic Spongofauna

An analysis of 483 remotely operated vehicle (ROV) dives carried out along the Italian coast on hard substrata at mesophotic depths (40–200 m) allowed an overview of the rich sponge diversity (53 taxa) of the deep continental platform to be obtained for the first time. About 40% of the potential actual species diversity was recognisable using ROV, suggesting that this group is among the richest yet underestimated using this technology in contrast to other megabenthic taxa. Additionally, the study allowed us to gather data on the current basin-scale distribution and bathymetric limits of five common and easily identifiable demosponges with up to 55% occurrence in the explored sites: Aplysina cavernicola, the group Axinella damicornis/verrucosa, Chondrosia reniformis, Foraminospongia spp., and Hexadella racovitzai. Four of these latitudinal distributions were characterised by high occurrence in the Ligurian Sea and a progressive decrease towards the south Tyrrhenian Sea, with an occasional second minor peak of occurrence in the Sicily Channel. In contrast, Foraminospongia spp. showed a maximum occurrence on the offshore reliefs and a second one in the North–central Tyrrhenian Sea, while it was almost absent in the Ligurian Sea. Trophic and biogeographic reasons were discussed as possible causes of the double-peak distributions. The vertical distributions support a more consistent occurrence of all considered taxa in deeper waters than previously known. This suggests that they may more typically belong to the mesophotic realm than the shallow waters, owing to a more extensive sampling effort in the deeper depth range. The five target taxa are typical or associated species of seven reference habitats in the recently revised UNEP/SPA-RAC classification. However, they may create such dense aggregations that they should be listed as new facies in the abovementioned classification.

Regional range extension of two xanthid crab species (Decapoda, Brachyura) to the mid-Sanriku Coast, the coldest waters off Honshu, Japan

Abstract This paper reports the first occurrences of two brachyuran crab species of the family Xanthidae MacLeay, 1838, viz., Actaea semblatae Guinot, 1976 and Gaillardiellus orientalis (Odhner, 1925), from the mid-Sanriku Coast, along the Pacific coast of northeastern Japan. While these records do not represent the northern limit of distribution of these species, they do show a range extension into the coldest waters of Honshu, the main island of Japan, probably due to global warming and changes in flow patterns of the local sea currents.

Generation of the flat-top beam using convolutional neural networks and Gerchberg-Saxton algorithm

Abstract Laser technology has made rapid progress in recent years and has been widely used in various fields such as medicine, biology, military, and materials science. However, the limitations of traditional Gaussian intensity distribution of the laser beams in applications have prompted the emergence and development of flat-top beam shaping technology, which has received widespread attention. Here, we introduce a new method for generating flat-top beams that combines the traditional Gerchberg-Saxton algorithm with convolutional neural networks, using spatial light modulators to achieve flat-top beam shaping. A comparative analysis was conducted by comparing the root mean square error and diffraction efficiency of the generated flat-top beam with the results obtained using only the traditional Gerchberg-Saxton algorithm. Compared with the traditional Gerchberg-Saxton algorithm, the method proposed in this paper can generate a flat-top beam with smaller differences from the target light intensity and higher energy utilization, providing new possibilities for the application of laser technology.

Land-use determines the distribution of large branchiopods in climatically homogeneous northern Pannonia

Large branchiopods are key biota of temporary pools in Central European lowlands. Due to land use changes, they are among the most threatened aquatic invertebrates in Europe. The lack of information on the main drivers of species distribution hinders effective protection and conservation prioritisation. We selected eight branchiopod species with representative data on their occurrence in the northern Pannonia to identify the most important drivers of their distribution and to predict their distribution in unexplored temporary pools across the Pannonian region of southern Slovakia, south-eastern Czech Republic, and eastern Austria. Data on pool size and isolation, soil characteristics, land use and climate were used to generate species distribution models using five modelling techniques and ensemble predictions. The distribution of species was mainly affected by the proportion of arable land within the pool (e.g. Triops cancriformis, Leptestheria dahalacensis), land use (e.g. Eubranchipus grubii, Lepidurus apus) and distance from the river (e.g. Branchinecta ferox and Chirocephalus carnuntanus). Wetland size and habitat isolation were also important for some species, mainly for Branchipus schaefferi and Imnadia yeyetta, respectively. As we focused on a climatically homogeneous area, climatic conditions only had the most important effect on the distribution of species that have their distribution limit in northern Pannonia (B. ferox, C. carnuntanus, I. yeyetta). Overall, the diversity of large branchiopods increased with pool size, while decreased with distance to a river and habitat isolation. As some distribution patterns emerged repeatedly in the models, the effective protection can be simplified to consider species that require contrasting conditions. Particular attention should be paid to ephemeral wetlands on arable land, crucial habitats for large branchiopods, yet lacking any protection. Our results can contribute to better conservation of large branchiopods by facilitating surveys of species in understudied areas and improving the knowledge on the species environmental niches.

Flexible Control Limits for Interval-Valued Data Using Mixture Probability Distributions

Availability of data in different forms is a boon or bane as it may require different approaches to deal with. In fact, while the construction of control charts is straightforward if the data are real-valued, in many practical situations data are essentially interval-valued with observations often represented by minimum and maximum values. While there are only fewer attempts to develop control charts for interval-valued data, no simple-to-use approaches have been proposed to deal with such type of data. In this paper, considering the idea of the development of control limits for multi-stream processes, we propose to make use of the mixture probability distributions approach to determine control limits for the interval-valued data. The resulting control limits are flexible in nature as they are linked to the control limits of the overall distribution that is based on the average of the means of two upper and lower populations along with their respective standard deviations. We have studied and numerically evaluated the average run length (ARL) properties of the proposed control chart to demonstrate the ways of determining the control chart coefficients. The proposed control chart is then illustrated using a dataset and conclusions are drawn based on the results.

The Mosquitoes (Diptera: Culicidae) of Sonora: Distribution, Ecology, and the First Records of Aedes deserticola Zavortink and Toxorhynchites septentrionalis (Dyar and Knab) in México

The diversity and distribution of mosquitoes from Sonora, Mexico, was documented through entomologic surveys conducted in the four physiographic regions and sub-regions of Sonora: the Sonoran Plain, the Sierra Madre Occidental, the Northern Mountains and Plains, and the Pacific Coastal Plain. Immature stages were collected from aquatic habitats, while adult mosquitoes were collected using Shannon traps, resting in vegetation, and by human landing collections. Overall, 11,316 specimens, which comprised 493 larvae, 224 larval exuviae, 400 pupal exuviae, 33 pupae, 4552 females, 5607 males, and seven male genitalia, were identified. Two subfamilies: Anophelinae and Culicinae, seven tribes, 10 genera, 23 subgenera, and 56 species are reported below. Of these, one tribe, one genus, five subgenera, and 15 species were recorded for the first time in Sonora. Two species, Aedes deserticola Zavortink and Toxorhynchites septentrionalis (Dyar and Knab), are the first recordings of their kind nationwide. Toxorhynchites septentrionalis was also barcoded with the cytochrome oxidase subunit 1 (COI) gene. The presence of Psorophora columbiae (Dyar and Knab) is confirmed in Mexico. Taxonomic notes, new geographic distribution limits of mosquitoes in Sonora, and information regarding their importance as disease vectors are provided. By adding Ae. deserticola and Tx. septentrionalis and confirming Ps. columbiae in Mexico, there are currently 251 mosquito species in the Country.

Influence of Spawning and Nursery Ground Environmental Changes on Walleye Pollock Catches Along the Eastern Coasts of Korea and Japan After the Late-1980s Climate Regime Shift

The eastern coasts of Korea (ECK) and Japan (ECJ) are located at the southernmost limit of walleye pollock distribution in the Northwest Pacific. Following the climate regime shift (CRS) in the late 1980s, pollock catches in these regions have declined sharply, with different trends emerging. This study examined the relationship between environmental factors, such as sea surface temperature (SST) and habitat suitability, and changes in pollock catches from the late 1980s to 2022. From the late 1980s to the late 1990s, El Niño and positive Pacific decadal oscillation (PDO) phases dominated, increasing SST in the ECK and ECJ habitats and rapidly decreasing catches. Although spawning grounds (SGs) have maintained high habitat suitability, nursery ground (NG) suitability has declined. From the late 1990s to 2022, La Niña and negative PDO phases prevailed, with SST continuing to rise along the ECK, further reducing catches. SG suitability remained high, but NG suitability declined. Along the ECJ, SST decreased after the late-1990s CRS, stabilizing catches. After the mid-2010s, the SST increased along the ECJ, reducing pollock catches, although SG suitability remained high. This study elucidates SST changes during early life stages and their effects on pollock catch, habitat, and resources in future marine environments.

A unifying approach to distributional limits for empirical optimal transport

A unifying approach to distributional limits for empirical optimal transport

Surprisingly wide climatic niche breadth of a relict mountain species raises hope for survival under climate change

AbstractAimsWe assessed the juvenile climatic niche breadth of a relict mountain species by comparing field observations and transplant experiments within and beyond the elevational limits of its distribution range.LocationLebanon – Near East – Mediterranean region.MethodsWe studied the survival and growth of the Cedar of Lebanon (Cedrus libani) to determine the lower and upper elevational range limits of its juvenile stage through an experimental setup with and without water supplementation and with potentially competing species as a control. The experiment included eight common gardens at elevations ranging from 110 to 2330 m, within and far beyond the warm and cold limits of Cedar distribution observed under natural conditions.ResultsWe observed unexpectedly high survival and growth rates of Cedar at elevations well below the range of its natural distribution in Lebanon. Below the observed warm limit, water stress at very low elevations and competition at low and medium elevations limited juvenile survival. In contrast, cold temperature and water stress limited survival at elevations slightly above the observed upper natural limit. The experimental setup demonstrated that the elevation range suitable for Cedar growth and survival was twice as wide as the range within which Cedar is observed under natural conditions.Main ConclusionsHigh survival rates experimentally observed beyond the warm limit of the natural distribution range of the Cedar of Lebanon raise hope for its resilience to ongoing climate warming. If this pattern were frequent among montane species, it would challenge predictions of massive extinction with climate change and pave the way for promoting adaptive actions such as competition management to improve their survival.