Changes In Species Composition Research Articles

Nestedness of benthic diatom metacommunity in relation to species niche width and environmental variables in a large near-natural catchment

Insight into the non-random distribution patterns of species in different regions is a foundational aim of research in community ecology and biogeography. The nestedness pattern, which investigates changes in species composition and abundance, has been widely used in numerous studies. However, studies on the nestedness of benthic diatoms are extremely rare, and consequently little has been mentioned of their assemblage mechanisms. To fill this gap, based on 168 benthic diatom species from 147 sampling sites in the Thousand Island Lake (TIL) catchment, we calculated their nestedness and niche width with the aim of i) analyzing the nestedness of benthic diatoms communities with different attachment abilities in TIL; ii) calculating niche width differences between nested and idiosyncratic species with different attachment abilities; iii) investigating the differences in alpha and beta diversity between nested and idiosyncratic sites; iv) examining whether environmental variables influencing the nestedness of benthic diatom communities are dependent on attachment ability. The results demonstrated a significant nestedness pattern in the benthic diatom metacommunity, and the sampling sites of low attachment species not only exhibited a nestedness pattern, but also with a lower nestedness value compared to the sampling sites of all species. Nested and idiosyncratic species differed in niche width, whereas differences between nested and idiosyncratic species of low attachment species were smaller. Additionally, significant differences in alpha and beta diversity were observed between nested and idiosyncratic sites. Furthermore, it was revealed that the nestedness of benthic diatom metacommunity in our study area were mostly influenced by local environmental variables. Our study contributes to the understanding of the significant nestedness observed in benthic diatom metacommunity in TIL, highlighting its relevance to biodiversity conservation efforts.

Exploring the spectral variation hypothesis for α- and β-diversity: a comparison of open vegetation and forests

Abstract Airborne hyperspectral imaging holds great promise for estimating plant diversity and composition, given its unprecedented combination of aerial coverage, spatial resolution, and spectral detail. Recently, there has been renewed attention toward the spectral variation hypothesis (SVH), which predicts that higher spectral variation is correlated with greater plant diversity. While several studies have highlighted methodological challenges involved with the SVH, there is little consensus about when it yields strong predictions of taxonomic, functional, and phylogenetic diversity. In part, this may be because prior studies have not explicitly considered how underlying environmental gradients drive changes in spectral and species composition. In this study, we tested the SVH separately in open vegetation (i.e., grasses and shrubs) and in forests at five sites across Canada. Generalized additive models revealed that spectral diversity was a better predictor of functional α-diversity than of taxonomic or phylogenetic α-diversity in both vegetation types. Mantel tests and Procrustes analyses revealed weak to moderate associations between spectral and plant β-diversity and composition in open vegetation, and moderate associations in forests. The better fit in forests appeared to be influenced by the presence of an elevational gradient and associated species turnover (from deciduous to coniferous trees); we observed weaker relationships when examining only a subset of this gradient. We suggest that the high variability in the strength of associations between plant and spectral diversity reported to date might be affected by the presence of environmental gradients. Finally, we found that different wavelength bands contributed to spectral α-diversity in open vegetation vs. forests, suggesting different spectral features are important for different vegetation types. In conclusion, spectral diversity is a potentially powerful tool for biodiversity assessment, but it requires a context-specific approach.

Challenges of Including Wet Grasslands with Variable Groundwater Tables in Large-Area Crop Production Simulations

Large-scale assessments of agricultural productivity necessitate integrated simulations of cropland and grassland ecosystems within their spatiotemporal context. However, simultaneous simulations face limitations due to assumptions of uniform species distribution. Grasslands, particularly those with shallow groundwater tables, are highly sensitive to water availability, undergoing rapid species composition changes. We hypothesised that predicting above-ground biomass (AGB) remains challenging due to these dynamic responses. Ten years of data from four lysimeters at a German wet grassland site, with varying water table treatments, was utilised to test this hypothesis. Correlation analysis revealed a strong positive indirect effect of the water regime on AGB, with a one-year time lag (r = 0.97). The MONICA model initially exhibited fair agreement (d = 0.69) in simulating Leaf-Area-Index (LAI) but performed poorly in replicating AGB (d = 0.3). After removing the species composition change effect from the LAI and AGB datasets, the simulation notably improved, with the overall relative root mean square error (rRMSE) of AGB decreasing from 1.55 to 0.90 between the first and second simulations. This demonstrates MONICA’s ability to predict grass growth patterns amidst changing water supply levels for constant species composition. However, it needs a competition model to capture biomass growth changes with varying water supply.

Relative abundance and damage by species in the Lepidoptera borer complex of macadamia nuts in the Barberton area, South Africa

Larvae of the nut borer complex, which include Thaumatotibia leucotreta, T. batrachopa, Cryptophlebia peltastica and Ectomyelois ceratoniae, cause extensive economic damage to macadamias in South Africa. Monitoring the changing species composition in this complex over a growing season provides valuable information for managing populations. In this study, pheromone traps were placed in two orchards planted with two different cultivars and used to monitor moth numbers over a 28-week period, while larval numbers and nut damage were monitored weekly over a 21-week period from the onset of flowering. Larvae were identified using a combination of morphology and DNA sequences of ~658 bp of the cytochrome oxidase I (COI) gene. Both larval and moth numbers were dominated by T. leucotreta, followed by T. batrachopa, with respective trap catches of 69% and 27%. Spearman correlations indicated strong linear relationships between nut diameter and numbers of eggs per nut for both the Beaumont and 816 cultivars. Poor correlations were found between weekly moth numbers and the number of eggs per nut. A two- to three-week lag was observed between weekly T. leucotreta trap catches and egg numbers. In contrast, egg numbers correlated strongly with larval infestation levels and the incidence of damaged nuts. Although the numbers of eggs and larvae were higher in Beaumont than cv. 816 nuts, higher incidences of nuts with husk and kernel damage were recorded for cv. 816. This study highlights the importance of monitoring of moth and larval numbers in macadamia orchards and showed that such data could be used to predict pest incidence during the season. This study questions the norm in South Africa, which is that macadamia nut borer (MNB) is usually the most abundant species in the nut borer complex.

Strongly asymmetric interactions and control regimes in the Barents Sea: a topological food web analysis

IntroductionIncreasing temperature of the global ocean alters the spatial behavior of a number of species. From the northern Atlantic Ocean, species may shift their area towards the poles. This results in the atlantification of the Barents Sea, raising questions about possible changes in species composition, community structure and community control.MethodsWe address the question whether possible changes in community control can be detected and quantified based on simple network analytical measures applied to the food web. Based on unweighted (binary) and undirected (symmetric) data, we quantify the strength of direct and indirect interactions in the network, represent the most asymmetric effects in the asymmetry graph composed of directed and weighted links and study the overlap among trophic niches of organisms.Results and discussionWe support earlier findings suggesting that the ecosystem can possibly be characterized by wasp-waist control. This would mean that focusing management efforts on intermediate trophic levels is of high importance, providing indirect benefit for organisms also at lower and higher trophic levels.

Impacts of Invasive Plants on Native Vegetation Communities in Wetland and Stream Mitigation.

We sampled vegetation communities across plant invasion gradients at multiple wetland and stream mitigation sites in the Coastal Plain and Piedmont physiographic provinces of Virginia, USA. Impacts of invasion were evaluated by tracking changes in species composition and native vegetation community properties along the abundance gradients of multiple plant invaders. We found that native species richness, diversity, and floristic quality were consistently highest at moderate levels of invasion (ca. 5-10% relative abundance of invader), regardless of the identity of the invasive species or the type of mitigation (wetland or stream). Likewise, native species composition was similar between uninvaded and moderately invaded areas, and only diminished when invaders were present at higher abundance values. Currently, low thresholds for invasive species performance standards (e.g., below 5% relative abundance of invader) compel mitigation managers to use non-selective control methods such as herbicides to reduce invasive plant cover. Our results suggest that this could cause indiscriminate mortality of desirable native species at much higher levels of richness, diversity, and floristic quality than previously thought. From our data, we recommend an invasive species performance standard of 10% relative invader(s) abundance on wetland and stream mitigation sites, in combination with vigilant invasive plant mapping strategies. Based on our results, this slightly higher standard would strike a balance between proactive management and unnecessary loss of plant community functions at the hands of compulsory invasive species management.

Integrative metagenomic analysis reveals distinct gut microbial signatures related to obesity

Obesity is a metabolic disorder closely associated with profound alterations in gut microbial composition. However, the dynamics of species composition and functional changes in the gut microbiome in obesity remain to be comprehensively investigated. In this study, we conducted a meta-analysis of metagenomic sequencing data from both obese and non-obese individuals across multiple cohorts, totaling 1351 fecal metagenomes. Our results demonstrate a significant decrease in both the richness and diversity of the gut bacteriome and virome in obese patients. We identified 38 bacterial species including Eubacterium sp. CAG:274, Ruminococcus gnavus, Eubacterium eligens and Akkermansia muciniphila, and 1 archaeal species, Methanobrevibacter smithii, that were significantly altered in obesity. Additionally, we observed altered abundance of five viral families: Mesyanzhinovviridae, Chaseviridae, Salasmaviridae, Drexlerviridae, and Casjensviridae. Functional analysis of the gut microbiome indicated distinct signatures associated to obesity and identified Ruminococcus gnavus as the primary driver for function enrichment in obesity, and Methanobrevibacter smithii, Akkermansia muciniphila, Ruminococcus bicirculans, and Eubacterium siraeum as functional drivers in the healthy control group. Additionally, our results suggest that antibiotic resistance genes and bacterial virulence factors may influence the development of obesity. Finally, we demonstrated that gut vOTUs achieved a diagnostic accuracy with an optimal area under the curve of 0.766 for distinguishing obesity from healthy controls. Our findings offer comprehensive and generalizable insights into the gut bacteriome and virome features associated with obesity, with the potential to guide the development of microbiome-based diagnostics.

Zásoby uhlíku v lesních půdách a lesní hospodářství – review

The article summarizes and discusses studies focused on the carbon stock in forest soils and the way it is affected by forestry operations with a focus on the Central European (Czech) region. In general, the methods enhancing forests´ vitality and stability are more important than the procedures aimed at carbon sequestration only, as the major risk for carbon stock in forest soils is represented by large-scale disturbances. Important factors that will influence the mitigation potential include the change of tree species composition, as the majority of forests in the Czech Republic is still represented by Norway spruce or Scots pine even-aged monocultures. Careful practices of logging and forest restoration are recommended, with minimal opening of the crown layer. The use of clear-cuts should be reserved mainly for afforestation of light-demanding tree species. Care should be taken of sustainable nutrients content in forest soils, as the soil quality plays substantial role in the future forest vitality, productivity and resilience. Forest protection and all measures preventing large-scale forest disturbances are of key importance for carbon sequestration.

Assessing species composition and structural attributes across different habitats to evaluate changes and management effectiveness of protected mangroves

Conservation and restoration of mangroves are necessary to meet global commitments for tackling the climate and biodiversity crises as well as reducing poverty. Management success is typically evaluated by estimating changes in vegetation cover, while changes in species composition and structural attributes across different habitats are often not considered. Here, we evaluated changes in mangrove composition, structural attributes, and drivers of change across Physically Stable Habitat (PSH), Diminished Tidal Inundation Habitat (DTIH), and Poor Drainage Habitat (PDH), for mangroves that have been protected for 22 years. We also analyzed the most likely ecological processes involved in the changes that have occurred. After 22 years, species remained the same in PSH and DTIH, but Rhizophora apiculata and Lumnitzera racemosa disappeared in PDH. Changes in relative proportions (number of trees of a species: total number of trees), and species abundance, varied between habitats. Additionally, changes in structural attributes also differed between habitat types over time suggesting they were driven by distinct ecological processes. Vegetation changes in PSH most likely occurred through a combination of ecologically important mangrove forest replacement and gap recovery processes, compared to only the gap recovery process in DTIH, and episodic changes due to stressful environmental conditions in PDH. Restoring hydrology, preventing sedimentation, planting proper seedlings of Avicennia marina should be conducted to save species and mangrove sustainability in PDH. It is highly recommended that managers follow a habitat-based approach to achieve effective management.

Differential roles of seed and sprout regeneration in forest diversity and productivity after disturbance

Natural regeneration after disturbances is a key phase of forest development, which determines the trajectory of successional changes in tree species composition and diversity. Regenerating trees can originate from either seeds or sprouts produced by disturbed trees with sprouting ability. Although both regeneration strategies often develop and co-occur after a disturbance, they tend to affect forest development differently due to significant functional differences. However, the origin of tree regeneration is rarely distinguished in post-disturbance forest surveys and ecological studies, and the differential role of seed and sprout regeneration in forest productivity and diversity remain poorly understood. To address these research gaps, we explored the role of sprout and seed regeneration in the formation of woody species diversity and above-ground biomass (AGB) productivity in early-stage forest development. Data were collected in two experimental forest stands in the Czech Republic, where trees were cut with varying intensities with the density of residual (uncut) trees ranging from 0 to 275 trees per hectare. All trees were mapped and their sizes were measured before cutting and then, either as a stump with sprouts or a residual tree, remeasured 11 years later. In addition, all tree saplings were mapped and measured 11 years after logging, and their origin (sprout or seed) was identified. To assess abundances and productivity, we estimated AGB of all 2,685 sprouting stumps of 19 woody species and 504 generative (i.e., seed origin) individuals of 16 woody species, using allometric equations. Mixed-effects models were used to analyze the effects of each regeneration strategy on woody species diversity and the total AGB under varying densities of residual trees. Nonmetric multidimensional scaling was used to evaluate the effect of regeneration strategies on species composition. AGB and diversity of sprouts were significantly higher than those of seed regeneration. Sprouts formed on average 97.1% of the total regeneration AGB in Hády and 98.6% in Soběšice. The average species richness of sprouts was 4.7 in Hády and 2.2 in Soběšice, while the species richness of seed regeneration averaged 2.1 and 1.1 in Hády and Soběšice, respectively. Increasing density of residual trees reduced AGB and diversity of both sprouts and seed regeneration, but seed regeneration was affected to a greater extent. Residual trees had an especially strong inhibitory effect on the establishment of seed regeneration. Consequently, seed-originated saplings were nearly absent in plots with high residual tree density, and abundant sprouts accounted for most of the AGB and diversity. However, unlike sprouts whose species composition resembled that of the original stand, seed regeneration brought in new species, enriching the stand’s overall species pool and beta diversity. Our results demonstrated differential roles of sprout and seed regeneration in the early stage of forest succession. Sprout regeneration was the main source of woody AGB productivity as well as species diversity, and its importance increased with the increasing density of standing mature trees. The results indicate the crucial yet previously underestimated role of sprout regeneration in post-disturbance forest dynamics. They suggest that the presence of residual mature trees, whether retained after partial cutting or undisturbed, can substantially suppress seed regeneration while the role of sprout regeneration in early succession becomes more distinctly evident.

Climate warming shifts riverine macroinvertebrate communities to be more sensitive to chemical pollutants.

Freshwaters are highly threatened ecosystems that are vulnerable to chemical pollution and climate change. Freshwater taxa vary in their sensitivity to chemicals and changes in species composition can potentially affect the sensitivity of assemblages to chemical exposure. Here we explore the potential consequences of future climate change on the composition and sensitivity of freshwater macroinvertebrate assemblages to chemical stressors using the UK as a case study. Macroinvertebrate assemblages under end of century (2080-2100) and baseline (1980-2000) climate conditions were predicted for 608 UK sites for four climate scenarios corresponding to mean temperature changes of 1.28 to 3.78°C. Freshwater macroinvertebrate toxicity data were collated for 19 chemicals and the hierarchical species sensitivity distribution model was used to predict the sensitivity of untested taxa using relatedness within a Bayesian approach. All four future climate scenarios shifted assemblage compositions, increasing the prevalence of Mollusca, Crustacea and Oligochaeta species, and the insect taxa of Odonata, Chironomidae, and Baetidae species. Contrastingly, decreases were projected for Plecoptera, Ephemeroptera (except for Baetidae) and Coleoptera species. Shifts in taxonomic composition were associated with changes in the percentage of species at risk from chemical exposure. For the 3.78°C climate scenario, 76% of all assemblages became more sensitive to chemicals and for 18 of the 19 chemicals, the percentage of species at risk increased. Climate warming-induced increases in sensitivity were greatest for assemblages exposed to metals and were dependent on baseline assemblage composition, which varied spatially. Climate warming is predicted to result in changes in the use, environmental exposure and toxicity of chemicals. Here we show that, even in the absence of these climate-chemical interactions, shifts in species composition due to climate warming will increase chemical risk and that the impact of chemical pollution on freshwater macroinvertebrate biodiversity may double or quadruple by the end of the 21st century.

Ectoparasites of wild rodents in forest sites invaded and uninvaded by Maesopsis eminii in Amani nature forest reserve, Tanzania

Parasites are important component of communities in a forest ecosystem with profound effects on trophic interactions such as food web. Modification of the forest structure (e.g. changes in species composition and abundance of key species) can have a strong impact on the occurrence, diversity, and abundance of parasites, with subsequent repercussions for ecosystem functioning. In this study, we compared the occurrence and abundance of wild rodents’ ectoparasites from forest sites invaded and uninvaded by an invasive tree, Maesopsis eminii in Amani Nature Forest Reserve, Tanzania. Three large plots (40 m × 100 m) were randomly established in each forest sites invaded and uninvaded by M. eminii. In each plot, 50 Sherman traps were systematically placed at 10 m interval for capturing wild rodents through a capture-mark-recapture technique. Wilcox rank sum test was used to compare for differences in the abundance of infested rodents and ectoparasites between the invaded and uninvaded forest sites. A total of 297 individual rodents were captured and screened for ectoparasites, including 174 rodents from uninvaded forest site and 123 rodents from invaded forest site. The number of infested rodents were significantly (W = 8592, P < 0.001) greater in uninvaded forest site (66.27%) than in the invaded forest site (36.2%). Furthermore, a significant greater number of Echinolaelaps echidninus (W = 1849, P < 0.01) and Dinopsyllus ellobius (W = 2800.5, P < 0.05) ectoparasites were found in uninvaded as compared to the invaded forest sites. The results of this study suggest that the invasion and dominance by, M. eminii in Amani Nature Reserve has created unfavorable conditions for rodents and ectoparasites and therefore impacting the diversity and function of the forest ecosystem. We recommend prevention of further introduction of the M. eminii outside their natural range and mitigating the impact of the established M. eminii in Amani Forest Nature Reserve.

Intrinsic and extrinsic drivers of organic matter processing along phosphorus and salinity gradients in coastal wetlands

Abstract Climate change is accelerating sea‐level rise and saltwater intrusion in coastal regions world‐wide and interacting with large‐scale changes in species composition in coastal wetlands. Quantifying macrophyte litter breakdown along freshwater‐to‐marine coastal gradients is needed to predict how carbon stores will respond to shifts in both macrophyte communities and water chemistry under changing environmental conditions. To test the interactive drivers of changing species identity and water chemistry, we performed a reciprocal transplant of four macrophyte litter species in seven sites along freshwater‐to‐marine gradients in the Florida Coastal Everglades. We measured surface water chemistry (dissolved organic carbon, total nitrogen and total phosphorus), litter chemistry (% nitrogen, % phosphorus, change in N:P molar ratio, % cellulose and % lignin as proxies for recalcitrance) and litter breakdown rates (k/degree‐day). Direct effects of salinity and surface water nutrients were the strongest drivers of k, but unexpectedly, litter chemistry did not correlate with litter k. However, salinity strongly correlated with changes in litter chemistry, whereby litter incubated in brackish and marine wetlands was more labile and gained more phosphorus compared with litter in freshwater marshes. Our results suggest that litter k in coastal wetlands is explained by species‐specific interactions among water and litter chemistries. Water nutrient availability was an important predictor of breakdown rates across species, but breakdown rates were only explained by the carbon recalcitrance of litter in the species with the slowest breakdown (Cladium jamaicense), indicating the importance of carbon structure, and species identity on breakdown rates. Synthesis. In oligotrophic ecosystems, nutrients are often the primary driver of organic matter breakdown. However, we found that variation in macrophyte breakdown rates in oligotrophic coastal wetlands was also explained by salinity and associated seawater chemistry, emphasising the need to understand how saltwater intrusion will alter organic matter processing in wetlands. Our results suggest that marine subsidies associated with sea‐level rise have the potential to accelerate leaf litter breakdown. The increase in breakdown rates could either be buffered or increase further as sea‐level rise also shifts macrophyte community composition to more or less recalcitrant species.

Update to Floral Diversity at Gujarat Institute of Desert Ecology (GUIDE) Campus Along with New Distribution of Salsola Oppositifolia Desf. in Kachchh

This study explores the biodiversity dynamics within the prestigious Gujarat Institute of Desert Ecology (GUIDE) campus in Bhuj, India, over the span of eight years. Fieldwork conducted during pre-monsoon and post-monsoon periods revealed a significant increase in plant species, genera, and families compared to previous assessments. The taxonomic diversity analysis revealed 239 plant species representing 180 genera and 62 families, with trees, herbs, and shrubs contributing prominently. Fabaceae appeared as the dominant family, followed by Poaceae and Malvaceae. Comparative analysis with previous studies established changes in species composition, notably an increase in tree species and a decrease in herbs. Of particular interest is the discovery of the second distribution of Salsola oppositifolia Desf. on the campus, a plant species first recorded in India in 2022 from Great Rann of Kachchh. The study highlights the crucial role of urban green spaces in supporting biodiversity. With 239 plant species thriving within the campus's urban infrastructure, this study highlights the potential of urban forestry in promotion biodiversity conservation and ecological resilience. Future research directions include exploring the ecological roles of vegetation and development public awareness about the multi-layered benefits of plants beyond oxygen production.

Seasonal variations of a coastal fish community in relation to environmental parameters - A case study of the Sylt-Rømø Bight, southeastern North Sea

The Wadden Sea is a transition area between land, rivers, and the North Sea. It is of great ecological importance for a wide range of fish species that use it in the course of their life cycle for various purposes. It is a highly dynamic environment and is subject to strong seasonal patterns and annual variations in abiotic conditions. The Sylt-Rømø Bight (SRB) is a semi-enclosed tidal basin in the northern Wadden Sea between the islands of Sylt (Germany) and Rømø (Denmark). Monthly monitoring data of juvenile fish taken in the SRB from 2007 to 2019 were analyzed to determine the changes in species composition in comparison to previous monitoring programs (1989–1995). The long-term trends, common patterns, and potential effects of environmental parameters (sea surface temperature (SST), salinity, chlorophyll a, and the North Atlantic Oscillation (NAO) winter indices) were determined. In total, 55 species were recorded and only 22 of these together accounted for more than 95% of the total abundance for the entire monitoring. Results showed a changed species composition as we did not find two boreal, one Lusitanian, and one circum-temperate species recorded in the previous programs. Instead, one boreal, six Lusitanian, and one Atlantic species were observed for the first time. The fish community was dominated by high seasonal fluctuations of abundance with either dome-shaped, increasing, or decreasing trends. Dynamic Factor Analysis (DFA) partitioned the fish community into three seasonal assemblages based on SST preferences. Redundancy Analysis (RDA) revealed that environmental parameters explained 29 % of the variations in the fish community. These variances were partly a result of the spring immigration of Lusitanian species and the emigration of boreal species and vice versa in autumn. The absence of four previously reported species and the addition of eight new species support the hypothesis that warm-adapted species are increasing in the Wadden Sea. The inclusion of these seasonal variations into conservation and management practices is critical to the sustainable management of marine and coastal ecosystems covering spawning, nursery, and feeding grounds.

Thrips Species Composition in Ontario Greenhouse Floriculture: Innovative Identification Tools and Implications for Integrated Pest Management.

Proper species identification is the keystone of successful integrated pest management (IPM). However, efforts to identify thrips species in Canadian greenhouses have not been formally made since the 1980s. In response to recent increases in crop damage, we sampled thrips communities from eight commercial floriculture greenhouses in the Niagara region (Ontario, Canada) from May until August 2016. Selected sites were revisited in 2017, 2018, and 2019 to determine changes in species composition over time. Western flower thrips (Frankliniella occidentalis (Pergande)), along with onion thrips (Thrips tabaci Lindeman), constituted the majority of species found. Other pest species (less than 8% of specimens across all sampling years) included poinsettia thrips (Echinothrips americanus Morgan), chrysanthemum thrips (Thrips nigropilosus Uzel), and Frankliniella fusca (Hinds). Further investigations of thrips outbreaks in Ontario from 2016 to 2023 revealed other important species, including Thrips parvispinus (Karny), Hercinothrips femoralis (Reuter), and Scirtothrips dorsalis Hood. The current biocontrol strategies used in Ontario floriculture crops for western flower thrips do not adequately control onion thrips or other thrips pests in ornamental crops, making identification a fundamental step in determining whether biocontrol or chemical control strategies should be implemented. However, traditional taxonomic keys are inaccessible to non-specialists due to their technical difficulty. Using the data gathered in these surveys, we developed a simplified, illustrated identification key for use by growers and IPM consultants.

Species composition of two communities of Mexican crane flies (Diptera: Tipulomorpha: Tipuloidea) separated by a geographic barrier, with additional notes and new records

ABSTRACT The presence or absence of species in a specific area and their distribution in geographic space are consequences of various factors, including geographic barriers. This study analyzes the change in species composition of two crane fly communities separated by a geographic barrier in the state of Veracruz, Mexico. Crane flies were collected using Malaise traps in 10 sites across two transects along the Misantla river (MT) and Actopan river (AT) basins, divided by the Chiconquiaco mountain range, through quarterly samplings over three years. A total of 559 specimens belonging to 60 species were collected, with 45 in MT (23 exclusive) and 37 species in AT (15 exclusive). The species composition differed by more than 60% between transects, primarily due to turnover; with higher values and a similar pattern among the sites along the transects, it is suggested that geographic barrier could be a factor in the change in composition. Additionally, three new and 41 potential new records for Mexico and 10 new records for Veracruz are reported, increasing the species records in Veracruz to 90 and in the country to 376. This study represents the first assessment of crane flies species composition at a specific site in Mexico.

Dynamics of fish community structure in the Yeosu Coast, Korea: A comprehensive analysis of daily set-net catch data during 2008–2022

This study focuses on the Yeosu Coast, a critical ecological and economic zone on the Korean Peninsula. We conducted a comprehensive analysis of fish data obtained from daily set nets for the period of 2008–2022 (excluding 2017) to investigate variations in fish composition and community structure over a 15-year period. The catches were characterized by a prevalence of warm-water fish species, reflecting the temperate and subtropical character of the Yeosu Coast. The total catch during the study period was 3210.8 tonnes, with 2010 and 2016 registering the highest and lowest catches, respectively. Our analysis identified sea surface temperature as a primary factor correlated with these changes in species composition. The two dominant species, Scomberomorus niphonius (Cuvier, 1832) and Engraulis japonicus Temminck et Schlegel, 1846 together accounted for a remarkable 78.9% of the total catch. Notably, the Shannon–Weaver diversity index values were lower in 2015 than in 2008, indicating potential shifts in the community structure. Our analysis identified sea surface temperature as the most dominant factor that influenced these changes in species composition. Furthermore, we highlight the significant threats posed by climate change and the increasing number of jellyfish challenging fisheries on the Yeosu Coast. These threats have the potential to result in diminished set-net catches and declining biodiversity within this valuable ecosystem. Our findings underscore the importance of monitoring and addressing these ecological shifts to ensure the long-term sustainability of Yeosu Coast fisheries.

Upper mesophotic reef fish assemblages at Bahía de Banderas, Mexico.

There is no information on the species associated with the mesophotic reefs of Banderas Bay, located in the central Mexican Pacific. This study analysed the reef fish assemblage from three depths (50, 60 and 70 m) in three sampling sites of the southern submarine canyon of the Bay: Los Arcos, Bajo de Emirio and Majahuitas. Several analyses were performed to test the hypothesis that there are important differences in fish abundance and species composition between sites and depths. Twenty-two species of bony fishes grouped in 14 families were recorded. PERMANOVA results showed that there were no significant differences in fish diversity parameters between sites, indicating a certain uniformity in their distribution. However, nine species were exclusive to one site and depth (five singleton species with only one individual recorded and four unique species recorded only once). On the other hand, there were significant differences between depths, mainly between 50 and 70 m. Diversity decreases with depth and species composition changes. SIMPER, Shade Plot and NMDS analysis show the most representative species at each depth, with at least half of the species (11) recorded only at 50 m and four species at the deeper levels (60 - 70 m). The observed assemblage includes several of the most caught species in the shallow water artisanal fishery, which is the most traditional and common type of fishery in the Bay. In addition, the Pomacanthuszonipectus (Cortés angelfish) is of particular interest, as it has a special protection status in the official Mexican standard (NOM-059-SEMARNAT, 2010) due to its use as an ornamental species in aquaria. We hypothesised that the mesophotic zone may serve as a refuge for these fishes, so we propose that the information obtained is an important basis for new research aimed at the sustainable management of fisheries in the area.

Tree species composition affects litter eco‐hydrological function in Pinus massoniana conifer‐broadleaf mixed forest stands in southwest China

AbstractAlthough changes in tree species composition profoundly affect the structure, function, and processes of mixed forest ecosystems, there is limited knowledge on the effects of these changes on the hydrological functions of the litter layer in Pinus massoniana conifer‐broadleaf mixed forests in subtropical mountains. Here, we investigated three typical P. massoniana forest stands in southwest China: P. massoniana‐Liquidambar formosana conifer‐deciduous broadleaf mixed forest (Pm + Lf), P. massoniana‐Castanopsis eyrei conifer‐evergreen broadleaf mixed forest (Pm + Ce), and P. massoniana plantation (Pm), and conducted field investigations (litter composition and mass) and indoor immersion experiments to analyse the litter water‐holding capacity (LWHC) of forest stands in their natural state and with artificial ratios combining mixed (needle‐leaf and broad‐leaf) litters. The total litter mass did not significantly differ among the three forest stands (p &gt; 0.05), but significant differences were observed in the needle‐leaf (0.67–2.92 t hm−2), broad‐leaf (0.32–1.89 t hm−2) and bark (0.11–0.34 t hm−2) masses in the undecomposed layer. The LWHC of different stand types was in the order of Pm + Lf &gt; Pm + Ce &gt; Pm. The maximum water‐holding capacity of different artificial ratios of mixed litters was positively proportional to the broad‐leaf mass and inversely proportional to the needle‐leaf mass, and the P. massoniana‐L. formosana mixed litter had a higher maximum water‐holding capacity than the P. massoniana‐C. eyrei mixed litter. The LWHC of mixed forests is mainly influenced by stand structure (tree composition) and litter characteristics, and is positively correlated with leaf area, thickness, dry matter content, and surface roughness. This study revealed that the LWHC can be significantly affected by different P. massoniana stands in subtropical mountains. This study will aid the sustainable and ecological management of forest in subtropical mountains, and P. massoniana plantations should be gradually converted into mixed conifer‐broadleaf forests with greater LWHC and buffering capacity.