Subtropical Island Research Articles

Divergent ecological responses to typhoon disturbance revealed via landscape-scale acoustic monitoring.

Climate change is increasing the frequency, intensity, and duration of extreme weather events across the globe. Understanding the capacity for ecological communities to withstand and recover from such events is critical. Typhoons are extreme weather events that are expected to broadly homogenize ecological dynamics through structural damage to vegetation and longer-term effects of salinization. Given their unpredictable nature, monitoring ecological responses to typhoons is challenging, particularly for mobile animals such as birds. Here, we report spatially variable ecological responses to typhoons across terrestrial landscapes. Using a high temporal resolution passive acoustic monitoring network across 24 sites on the subtropical island of Okinawa, Japan, we found that typhoons elicit divergent ecological responses among Okinawa's diverse terrestrial habitats, as indicated by increased spatial variability of biological sound production (biophony) and individual species detections. This suggests that soniferous communities are capable of a diversity of different responses to typhoons. That is, spatial insurance effects among local ecological communities provide resilience to typhoons at the landscape scale. Even though site-level typhoon impacts on soundscapes and bird detections were not particularly strong, monitoring at scale with high temporal resolution across a broad spatial extent nevertheless enabled detection of spatial heterogeneity in typhoon responses. Further, species-level responses mirrored those of acoustic indices, underscoring the utility of such indices for revealing insight into fundamental questions concerning disturbance and stability. Our findings demonstrate the significant potential of landscape-scale acoustic sensor networks to capture the understudied ecological impacts of unpredictable extreme weather events.

Got milkweed? Genetic assimilation as potential source for the evolution of nonmigratory monarch butterfly wing shape.

Monarch butterflies (Danaus plexippus) are well studied for their annual long-distance migration from as far north as Canada to their overwintering grounds in Central Mexico. At the end of the cold season, monarchs start to repopulate North America through short-distance migration over the course of multiple generations. Interestingly, some populations in various tropical and subtropical islands do not migrate and exhibit heritable differences in wing shape and size, most likely an adaptation to island life. Less is known about forewing differences between long- and short-distance migrants in relation to island populations. Given their different migratory behaviors, we hypothesized that these differences would be reflected in wing morphology. To test this, we analyzed forewing shape and size of three different groups: nonmigratory, lesser migratory (migrate short-distances), and migratory (migrate long-distances) individuals. Significant differences in shape appear in all groups using geometric morphometrics. As variation found between migratory and lesser migrants has been shown to be caused by phenotypic plasticity, and lesser migrants develop intermediate forewing shapes between migratory and nonmigratory individuals, we suggest that genetic assimilation might be an important mechanism to explain the heritable variation found between migratory and nonmigratory populations. Additionally, our research confirms previous studies which show that forewing size is significantly smaller in nonmigratory populations when compared to both migratory phenotypes. Finally, we found sexual dimorphism in forewing shape in all three groups, but for size in nonmigratory populations only. This might have been caused by reduced constraints on forewing size in nonmigratory populations.

Density and ecological drivers of free‐ranging cat abundance and activity in Madeira Island, Macaronesia

AbstractMammalian predators introduced to oceanic islands pose a significant threat to biodiversity and have led to numerous extinctions. Free‐ranging cats are particularly problematic due to their predatory habits and negative impact on conservation. However, there is limited information on the ecology and population status of free‐ranging cats in insular ecosystems, where they often represent the apex terrestrial predator. Using a peri‐urban protected area in the subtropical island of Madeira as a case study, we employed camera traps to assess the density of free‐ranging cats and investigate the ecological drivers influencing their abundance and activity in nonurban insular habitats. Based on 582 trapping‐nights, we identified 25 individual cats from 156 cat detections. Spatially explicit capture–recapture models revealed a density of 1.4 cats per km2. Cat activity was positively affected by both the proportion of rocky areas in the landscape and the distance to human resource subsidies, whereas no significant driver was found for abundance. Our results indicate that cats are highly abundant throughout the protected area and suggest that their core home ranges are associated with rocky terrain, away from the most humanized sections of the park. Free‐ranging cats do not appear to heavily rely on anthropogenic food sources, signaling that they may rely mostly on wild prey to fulfill their dietary needs. Their preference for rocky areas could be explained by the increased availability of shelter and prey, such as the Madeira wall lizard (Teira dugesii). Notably, cat abundance and activity were particularly high in the vicinity of the only known breeding colony of the locally threatened Manx shearwater (Puffinus puffinus) on Madeira Island. Our findings suggest that cats pose a significant threat to the native vertebrate fauna of the protected area and thus their management, particularly during the breeding season of the Manx shearwater, should be considered.

Antibacterial properties and characterization of metabolite extracts of mangrove soil-associated bacteria from a subtropical island: Evaluation of their activity against common human pathogens and biofilms of clinical importance

We are now in the "post-antibiotic era" where there is a crucial need to develop new antibiotics with novel modes of action. Mangrove ecosystems are unique and shelter diverse halophilic microorganisms that can potentially produce novel antibacterial metabolites. In this work, extracts from four mangrove-derived isolates, namely Z3RZ1, Z3RZ3, Z3PZ1 and Z5PZ2, were tested for potential antibacterial activity against six pathogens: Escherichia coli (ATCC 25922), P. aeruginosa (ATCC 27853), Bacillus cereus (ATCC 11778), Staphylococcus aureus (ATCC 29213), Staphylococcus epidermidis (ATCC 12228) and Klebsiella pneumonia (ATCC 13883). The four extracts were tested for their antibiofilm potential against E. coli (ATCC 25922) and P. aeruginosa (ATCC 27853). The extract with the best antibiofilm activity was chemically characterized by liquid chromatography-mass spectrometry (LC-MS). Sequence analyses of the four isolates showed closest similarity matches to Micrococcus luteus (Z3RZ1), Globicatella sanguinis (Z3RZ3), Shewanella indica (Z3PZ1), and Shewanella indica (Z5PZ2). The Z3RZ3 extract had the strongest antibacterial activity against five pathogens, with the lowest minimum inhibitory concentrations (MIC) ranging from 3.91 × 102 to 6.250 × 103 µg/ml. All four extracts showed strong activity (>75%) and very strong activity (>95%) against E. coli and a P. aeruginosa biofilm formation respectively. Z3RZ3 extract was by far the most potent in disrupting pre-formed P. aeruginosa biofilms, displaying 100% efficacy within a 2-hr period. The Z3RZ3 extract contained cyclopentenones, terpenes, anthraquinone, thioinosine, cyclic lactam, benzene derivatives, and macrolides. Our study highlights the potential of the mangrove environment as a mine of new bioactive compounds with antibacterial and antibiofilm activities.

An invasive appetite: Combining molecular and stable isotope analyses to reveal the diet of introduced house mice (Mus musculus) on a small, subtropical island.

House mice (Mus musculus) pose a conservation threat on islands, where they adversely affect native species' distributions, densities, and persistence. On Sand Island of Kuaihelani, mice recently began to depredate nesting adult mōlī (Laysan Albatross, Phoebastria immutabilis). Efforts are underway to eradicate mice from Sand Island, but knowledge of mouse diet is needed to predict ecosystem response and recovery following mouse removal. We used next-generation sequencing to identify what mice eat on Sand Island, followed by stable isotope analysis to estimate the proportions contributed by taxa to mouse diet. We collected paired fecal and hair samples from 318 mice between April 2018 to May 2019; mice were trapped approximately every eight weeks among four distinct habitat types to provide insight into temporal and spatial variation. Sand Island's mice mainly consume arthropods, with nearly equal (but substantially smaller) contributions of C3 plants, C4 plants, and mōlī. Although seabird tissue is a small portion of mouse diet, mice consume many detrital-feeding arthropods in and around seabird carcasses, such as isopods, flesh flies, ants, and cockroaches. Additionally, most arthropods and plants eaten by mice are non-native. Mouse diet composition differs among habitat types but changes minimally throughout the year, indicating that mice are not necessarily limited by food source availability or accessibility. Eradication of house mice may benefit seabirds on Sand Island (by removing a terrestrial, non-native predator), but it is unclear how arthropod and plant communities may respond and change. Non-native and invasive arthropods and plants previously consumed (and possibly suppressed) by mice may be released post-eradication, which could prevent recovery of native taxa. Comprehensive knowledge of target species' diet is a critical component of eradication planning. Dietary information should be used both to identify and to monitor which taxa may respond most strongly to invasive species removal and to assess if proactive, pre-eradication management activities are warranted.

Breakdown in seasonal dynamics of subtropical ant communities with land-cover change.

Concerns about widespread human-induced declines in insect populations are mounting, yet little is known about how land-use change modifies both the trends and variability of insect communities, particularly in understudied regions. Here, we examine how the seasonal activity patterns of ants-key drivers of terrestrial ecosystem functioning-vary with anthropogenic land-cover change on a subtropical island landscape, and whether differences in temperature or species composition can explain observed patterns. Using trap captures sampled biweekly over 2 years from a biodiversity monitoring network covering Okinawa Island, Japan, we processed 1.2 million individuals and reconstructed activity patterns within and across habitat types. Forest communities exhibited greater temporal variability of activity than those in more developed areas. Using time-series decomposition to deconstruct this pattern, we found that sites with greater human development exhibited ant communities with diminished seasonality, reduced synchrony and higher stochasticity compared with sites with greater forest cover. Our results cannot be explained by variation in regional or site temperature patterns, or by differences in species richness or composition among sites. Our study raises the possibility that disruptions to natural seasonal patterns of functionally key insect communities may comprise an important and underappreciated consequence of global environmental change that must be better understood across Earth's biomes.

Widespread arboreal foraging behavior in ground-dwelling birds and the urgency of life-history studies

Habitat changes can alter animal behaviors, especially of large-bodied animals. Landfowl (Galliformes) are a phylogenetically diverse group of large-bodied ground-dwelling birds that are generally considered reluctant flyers. However, some species of landfowl have also been found to forage in arboreal habitats, which could be particularly advantageous under declining habitat quality. However, the prevalence of arboreal foraging behavior (AFB) and how it relates to habitat changes are still unexplored. Here, we reviewed life-history traits associated with foraging behaviors in 305 species of landfowl worldwide and examined the prevalence of AFB across the global landfowl phylogeny. We also collected data from arboreal camera traps on 22 subtropical reservoir islands and six nearby mainland sites in the Thousand Island Lake region of China to assess AFB of Silver Pheasant (Lophura nycthemera), the largest landfowl in this lake system, with island area and isolation. Globally, at least 84 species of landfowl (28%) showed evidence of AFB, with a strong phylogenetic signal. Camera trapping revealed that Silver Pheasant tended to have AFB on small and isolated islands, as evidenced by the increased arboreal sampling efforts. Our study reveals that landfowl’s AFB is much more widespread than previously recognized, and suggests the importance of prioritizing large, connected habitats for the conservation of large-bodied animals like Silver Pheasant in the fragmented landscape. Finally, camera trapping emerges as a promising tool for recording landfowl’s life history and uncommon behaviors that can help us understand landfowl’s threats and aid conservation programs.

Impact of Pacific–Japan pattern on temperature and heatwave events in summer over Taiwan

AbstractThe prediction of heatwave events is vital to provide information on possible hazards caused by extremely high temperature. The Pacific–Japan (PJ) pattern is a significant climate variability that controls the summer climate over East Asia. Previous studies have reported that the meridional propagating wave structure associated with the PJ pattern can modulate summer temperature and heatwave characteristics over northeast Asian countries, such as Korea and Japan. Nevertheless, its impacts on the subtropical regions, including Taiwan, a mountainous subtropical island with an approximate population of 24 million, is not yet fully understood. In this study, we investigate the impacts of the PJ pattern on the summer temperature and heatwave characteristics in Taiwan on the interannual timescale using long‐term station‐based temperature and rainfall dataset. We found an island‐wide increase in temperature during the positive phase of the PJ pattern, which is characterized by an anticyclonic anomalous circulation over Taiwan. Meanwhile, the averaged effective area and frequency of heatwave extremes over Taiwan have increased significantly, indicating an increase of exposure to heatwaves. Our examinations of large‐scale environment suggest that the adiabatic warming due to subsidence anomaly associated with the anticyclone over Taiwan is primary contributor of surface warming, which is balanced by diabatic cooling and meridional advective cooling on a seasonal timescale. Our study consolidated the links between the PJ pattern as a climate driver, hot summers and increased summer heatwave events over Taiwan. By combining with the seasonal prediction systems and early warning systems, such understanding can help sectors that are vulnerable to heat stress to prepare for potential hazards.

THE ROLE OF DRILLING PREDATION IN ISOLATED, NUTRIENT-POOR ECOSYSTEMS: FIRST INSIGHTS FROM RAPA NUI, POLYNESIA

Abstract As a biotic interaction, drilling predation is affected by the evolutionary histories of the predator and prey, as well as the environment. A unique location with distinctive evolutionary histories and environmental conditions is the remote island of Rapa Nui. For mollusks, an evolutionary history in relative isolation has led to high rates of endemism (35–40%), in an area that has some of the most nutrient-poor waters of the global ocean. Here, we use death assemblages collected in Rapa Nui to answer two main questions: (1) How does a pervasive interaction like drilling predation play out in an isolated, oligotrophic marine system? and (2) What role do the environment (exposed vs. sheltered sites) and species traits (feeding, mobility, life habit) play in ‘protecting' the prey? We predicted that predation would be low relative to other tropical and subtropical islands given the oligotrophic conditions and found that the average drilling frequency (DF) was 5.67% (n = 6122). We observed no significant differences in DF between feeding guilds, mobility types, or life habits. Sheltered sites dominated by the infaunal bivalve Ctena bella had higher predation. In terms of passive defenses for C. bella, larger body size was not an effective defense against drilling predators. We show that drilling predation in Rapa Nui is lower than in high-latitude regions, and it is dependent on how sheltered or exposed sites are. Historically and currently, Rapa Nui has been subject to multiple anthropogenic stressors, including over-extraction and tourism, making efforts to understand its endemic species and their interactions fundamental.

Climatic stability and geological history shape global centers of neo- and paleoendemism in seed plants.

Assessing the distribution of geographically restricted and evolutionarily unique species and their underlying drivers is key to understanding biogeographical processes and critical for global conservation prioritization. Here, we quantified the geographic distribution and drivers of phylogenetic endemism for ~320,000 seed plants worldwide and identified centers and drivers of evolutionarily young (neoendemism) and evolutionarily old endemism (paleoendemism). Tropical and subtropical islands as well as tropical mountain regions displayed the world's highest phylogenetic endemism. Most tropical rainforest regions emerged as centers of paleoendemism, while most Mediterranean-climate regions showed high neoendemism. Centers where high neo- and paleoendemism coincide emerged on some oceanic and continental fragment islands, in Mediterranean-climate regions and parts of the Irano-Turanian floristic region. Global variation in phylogenetic endemism was well explained by a combination of past and present environmental factors (79.8 to 87.7% of variance explained) and most strongly related to environmental heterogeneity. Also, warm and wet climates, geographic isolation, and long-term climatic stability emerged as key drivers of phylogenetic endemism. Neo- and paleoendemism were jointly explained by climatic and geological history. Long-term climatic stability promoted the persistence of paleoendemics, while the isolation of oceanic islands and their unique geological histories promoted neoendemism. Mountainous regions promoted both neo- and paleoendemism, reflecting both diversification and persistence over time. Our study provides insights into the evolutionary underpinnings of biogeographical patterns in seed plants and identifies the areas on Earth with the highest evolutionary and biogeographical uniqueness-key information for setting global conservation priorities.

Assessing nitrogen flow and nitrogen footprint in the food system of a subtropical island with a scenario to mitigate nitrogen load impacted by trade-dependent agriculture

Recent hikes in fertilizer, feed, and food prices threaten the food security of island-dwelling people who rely heavily on imports to sustain food supply and production. The influx of reactive nitrogen (Nr) through imports increases nitrogen load and degrades the environment. To overcome these problems, a robust and sustainable food system must be developed. In this study, we aimed to evaluate the present nitrogen flow in the food system of Ishigaki Island, located in the subtropical zone of Japan, and propose a measure to improve it based on the nitrogen footprint concept. Results showed that the major Nr-loss pathways for agricultural activity on the island were ‘crop-unused’ (37%) and ‘manure’ (43%). In food production, most of the Nr loss to the environment was related to export products, and less than 30% was related to island consumers. To meet the demand of food supply on the island, 5.1 times greater amount of food Nr than that of produced for island consumers was imported from overseas regions, placing the burden of Nr loss on such regions. We found that agricultural activities on the island mainly used chemical fertilizer; less than 13% of cattle manure was reused. To reduce the influx of Nr, we created a scenario in which 30% of chemical fertilizer was replaced by cattle manure. Results indicated 70% of the cattle manure produced on the island was necessary to achieve this scenario. This system could reduce Nr imports and Nr loss on the island by 16% and 17%, respectively. The proposed food system can be extended to other islands to overcome the recent price hikes and conserve the environment. This study is the first to present a detailed nitrogen flow in the food system of a tropical/subtropical island by using the nitrogen footprint concept.

Reproductive characteristics and gamete development of the soft coral Sclerophytum cf. heterospiculatum in Okinawa Island, Japan

AbstractSexual reproduction data are important to understand how organisms can replenish their populations and proliferate on coral reefs. Despite the importance of such data, the reproductive characteristics of most soft coral species are still unknown. Here, we examined the reproductive strategies of a species from the often‐dominant genus Sclerophytum in a coral reef on subtropical Okinawa Island, Japan. DNA barcoding and histological examinations of the tissues were conducted to confirm colony conspecificity and identify reproductive characteristics, respectively, between March 2020 and March 2021. Results indicated that the studied species, identified as Sclerophytum cf. heterospiculatum, exhibits gonochorism with longer oogenesis and shorter spermatogenesis. Female colonies produced immature oocytes throughout the year, with mature oocytes observed from late July to early September, and thus, extended spawning is likely characteristic of this species. In male colonies, spermatogenesis took place over ~5 months, with spermaries present from April through August. Mature spermaries were noted beginning in July and the inferred peak of sperm release was between late August and early September, which suggests that spermatogenesis duration was ~5 months. The largest mean oocyte and spermary sizes (628.45 ± 61.36 and 240.04 ± 49.49 μm, respectively) were both recorded in August. Gamete spawning presumably occurred during the summer season, which suggests seasonality in reproduction as influenced by changes in seawater temperature. However, the proximate cue for exact dates of spawning could be the lunar period because the inferred release of spawning materials seemed to occur between full moon and last‐quarter moon phases in both the months of August and September. The results of this study represent the first detailed report of reproductive characteristics of the genus Sclerophytum in Japan.

Airborne microbiomes at a subtropical island in southern China: Importance of the northwest and southeast monsoons

Airborne microbes can survive in the atmosphere, travel intercontinental distances by air mass movement, and colonize in remote area through dry and wet deposition, thus forming a connection between oceanic, atmospheric, and terrestrial systems. However, studies linking the monsoon and bioaerosol transport are extremely rare. Here we applied high-throughput sequencing to investigate airborne microbial community succession on an island in Pearl River Estuary under summer and winter monsoon influence. The microbial communities from local potential sources (i.e., soil, leaf and surface seawater), water-soluble ions, organic carbon and elemental carbon were used to evaluate marine and terrestrial contribution. Our results revealed that airborne microbial communities underwent rapid changes during different monsoons influence (ANOSIM, P < 0.005), especially fungal aerosol. Fungal aerosols were dominant by Cladosporium, Debaryomyces, Rhodotorula, Fusarium, Aureobasidium and Candida during winter monsoon, while Coriolopsis, Ceriporia, Fomes, Phanerochaete, Trametes, Phlebia, and Antrodia were predominant fungal genera during summer monsoon. Redundant analysis showed that changes of air temperature and relative humidity caused by monsoon were the most important driven factors of airborne microbial communities in summer monsoon for airborne microbial communities. In addition, terrestrial sources were the most important contribution, especially that of soil for airborne bacteria. Some taxa were affected by atmospheric transport influenced by monsoon synoptic air mass movement.

Interspecific sociality alters the colonization and extinction rates of birds on subtropical reservoir islands.

Island biogeography theory has proved a robust approach to predicting island biodiversity on the assumption of species equivalency. However, species differ in their grouping behaviour and are entangled by complex interactions in island communities, such as competition and mutualism. We here investigated whether intra- and/or interspecific sociality may influence biogeographic patterns, by affecting movement between islands or persistence on them. We classified bird species in a subtropical reservoir island system into subcommunities based on their propensity to join monospecific and mixed-species flocks. We found that subcommunities which had high propensity to flock interspecifically had higher colonization rates and lower extinction rates over a 10-year period. Intraspecific sociality increased colonization in the same analysis. A phylogenetically corrected analysis confirmed the importance of interspecific sociality, but not intraspecific sociality. Group-living could enable higher risk crossings, with greater vigilance also linked to higher foraging efficiency, enabling colonization or long-term persistence on islands. Further, if group members are other species, competition can be minimized. Future studies should investigate different kinds of island systems, considering positive species interactions driven by social behaviour as potential drivers of community assembly on islands. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.

Evaluating the Losses and Recovery of GPP in the Subtropical Mangrove Forest Directly Attacked by Tropical Cyclone: Case Study in Hainan Island

The gross primary production (GPP) of the mangrove ecosystem determines the upper limit of the scale of its “blue carbon” sink. Tropical cyclones (TCs) are among the most important extreme events that threaten the subtropical mangrove ecosystem and have a serious impact on mangrove ecosystem GPP. However, there are somewhat insufficient scientific findings on regional-scale mangrove ecosystem GPP responding to large-scale weather events such as TCs. Therefore, we selected the subtropical Hainan Island mangrove ecosystem, where more than two TCs pass through per year, as the research area; selected direct-attack TCs as the research object; and took the mangrove vegetation photosynthesis light-use efficiency model established based on the eddy covariance observation data as the tool to evaluate the loss and recovery of mangrove ecosystem GPP after TCs attacked at a regional scale. We found that the TC impacted the mangrove ecosystem GPP through the photosynthetic area and rate, and the recovery of the rate occurred prior to the recovery of the area; the loss of mangrove ecosystem GPP is inversely proportional to the distance to the center of the TC and the distance to the coastline; and the canopy height, diameter at breast height, and aspect where the tree stands significantly influence the response of the mangrove ecosystem GPP to TCs. However, the response varies for different mangrove community compositions, soil conditions, and planting densities as well as different frequencies and intensities of TCs, and they should be analyzed in detail. This study is expected to provide technical and data support for the protection of blue carbon in a subtropical island mangrove ecosystem in response to extreme events and post-disaster recovery.

Data for manuscript "The isotopic composition of rainfall on a subtropical mountainous island"

Data for manuscript "The isotopic composition of rainfall on a subtropical mountainous island"

Sensible heat fluxes control cloud trail strength

AbstractConvective cloud bands known as “cloud trails” (CTs) are commonly found downwind of small islands (&lt;(100) km2) throughout the world. They occur primarily in the afternoon, and are known to form in response to land–sea contrasts under the presence of background flow. A set of idealized numerical experiments with 100‐m horizontal grid spacing is performed to quantify the relationship between the surface forcing produced by an island and the strength of the resulting CT circulation. These experiments are based on observed environmental conditions for which a CT occurred off Bermuda, a small subtropical island. For these simulations, the CT circulation is found to be controlled by the strength of the integrated excess heating of the flow as it passes over the island. This excess heating is in turn controlled by the strength of the island heat fluxes when the wind speed and the island geometry are kept constant. Our experiments show, all else equal, a linear relationship between CT circulation strength and the island surface heat flux.

Root biomechanical features and wind erosion resistance of three native leguminous psammophytes for coastal dune restoration

Taiwan is a subtropical mountainous island with fragile geological conditions and about 1566 km of coastline. Monsoon usually bring severe coastal erosion and dust storms. Canavalia lineata, Canavalia rosea and Vigna marina, three native pioneer leguminous psammophytes occurring on coastal sand dune areas, play important roles in reducing wind erosion in coastal regions. Nonetheless, its root biomechanical properties and wind erosion resistance are still unexplored. In this study, the root biomechanical properties of these plants were inspected using uprooting and tensile tests. Wind erosion resistance was estimated by wind tunnel tests. Our results showed that the growth charactersitics of C. lineata are superior than those of C. rosea and V. marina. Furthermore, the root pullout force of C. lineata (0.36 ± 0.04 kN) and C. rosea (0.36 ± 0.05 kN) are remarkably higher than that of V. marina (0.22 ± 0.02 kN). Root tensile strength of C. rosea (291.24 ± 11.89 MPa) plants is significantly greater than those of C. lineata (231.33 ± 9.47 MPa) and V. marina (95.78 ± 8.83 MPa) plants. Moreover, wind tunnel tests show that C. lineata has superior wind erosion resistance than C. rosea and V. marina. Altogether, these results clearly demonstrate that the priority species order for coastal dune restoration is: C. lineata > C. rosea > V. marina. These results contribute important strategy for ecological engineering of coastal management in sand dune areas.

Black coral forests enhance taxonomic and functional distinctiveness of mesophotic fishes in an oceanic island: implications for biodiversity conservation

The degradation of shallow ecosystems has called for efforts to understand the biodiversity and functioning of Mesophotic Ecosystems. However, most empirical studies have been restricted to tropical regions and have majorly focused on taxonomic entities (i.e., species), neglecting important dimensions of biodiversity that influence community assembly and ecosystem functioning. Here, using a subtropical oceanic island in the eastern Atlantic Ocean (Lanzarote, Canary Islands), we investigated variation in (a) alpha and (b) beta functional (i.e., trait) diversity across a depth gradient (0–70 m), as a function of the presence of black coral forests (BCFs, order Antipatharian) in the mesophotic strata, a vulnerable but often overlooked ‘ecosystem engineer’ in regional biodiversity. Despite occupying a similar volume of the functional space (i.e., functional richness) than shallow (< 30 m) reefs, mesophotic fish assemblages inhabiting BCFs differed in their functional structure when accounting for species abundances, with lower evenness and divergence. Similarly, although mesophotic BCFs shared, on average, 90% of the functional entities with shallow reefs, the identity of common and dominant taxonomic and functional entities shifted. Our results suggest BCFs promoted the specialization of reef fishes, likely linked to convergence towards optimal traits to maximize the use of resources and space. Regional biodiversity planning should thus focus on developing specific management and conservation strategies for preserving the unique biodiversity and functionality of mesophotic BCFs.

Occurrence of brown root rot in Ocean Expo Park, Okinawa, Japan: Infection route and preventive control measures

AbstractOcean Expo Park, established in 1976 on subtropical Okinawa Island, Japan, has approximately 8000 planted or naturally grown trees in an area of 77.2 ha. Windfall of these trees occurs mainly due to typhoons; wood chips made from the trunks and roots of windfall trees are commonly used as mulching material throughout the park areas, despite possible infection by pathogenic fungi such as Phellinus noxius, the pathogen causing brown root rot. P. noxius is distributed in tropical and subtropical areas worldwide and has a broad host range. The fungus can infect host plants with mycelia via root‐to‐root contact or with basidiospores. Here, we report the current status of tree damage caused by brown root rot in the park and infer the infection routes of P. noxius based on microsatellite markers. Among a total of 294 trees surveyed in the park, P. noxius was isolated from 13 trees of five species. P. noxius was observed more frequently on Ficus microcarpa than on other tree species. Ficus superba var. japonica was identified as a new host species, and Bombax ceiba was first recorded as a host plant of P. noxius in Japan. Among the 13 P. noxius isolates from the diseased trees, 2 isolates from adjacent diseased trees were considered to be of the same genet, while the other 11 isolates were different genets, indicating that infection by basidiospores occurred frequently among trees in the entire park, although spread via root systems also occurred between at least two adjacent trees. An identical genet was not detected at distant locations, which suggests that the disease does not spread via chips. However, mulching with chips can lead to wood decay due to decaying fungi other than P. noxius. Therefore, in accordance with the precautionary principle, the park currently prohibits the chipping and mulching of windfall or damaged trees and is considering disposal methods such as burning.