Taxa Richness Research Articles

Trees Are a Major Foraging Resource for Honeybees in the City

Large cities are typically characterized by a mosaic of green spaces that hold a remarkable variety of native and “exotic” plants. Urban beekeeping has gained increasing popularity. In order to characterize the “urban” in the honey, pollen diversity in 50 honey samples from 18 apiary locations in Vienna, Austria, was microscopically analyzed. The relative abundances of each plant taxon were determined by counting out 500 individual pollen grains per sample. In total, 202 taxa could be identified, with a median of 46 per sample. Taxa richness and diversity differed significantly across three years but did not so between urban and suburban apiaries. Despite trees comprising only roughly a quarter of all taxa, the amount of tree pollen was disproportionally high. The invasive Ailanthus altissima was predominant in 15 out of 50 samples. Other important non-native and/or ornamental trees included Sophora japonica, Gleditsia triacanthos, Castanea sativa, Koelreuteria paniculata, and Liriodendron tulipifera. Urban honey from Central Europe may typically comprise pollen taxa from Europe, East Asia, and North America alike. The results of this study show that intentionally planted, managed urban green spaces can support stable foraging resources for pollinators in cities.

Inventory of Shallow-Water Fouling Invertebrates of Long Island, New York

Invasive marine invertebrates are increasingly recognized as a potential disturbance to coastal ecosystems. We sought to better document the taxonomic composition of subtidal communities around Long Island to obtain a baseline that can be used to monitor current and future invasions of non-indigenous species. We placed settlement blocks at 18 sites along the coast of Long Island, New York, for three months. After recovering blocks at 12 sites, we analyzed the taxonomic composition of fouling communities on the blocks. We observed 64 invertebrate and 3 algal taxa, with large variation in taxon richness among sites. Multivariate analyses revealed that although taxon composition was significantly dissimilar between north and south shores, variation in dissimilarity did not differ significantly between shores. The high variability in taxon composition observed among sites indicates that additional research is needed to expand our knowledge of invertebrate diversity in the waters surrounding Long Island. Adding more sites and replicate blocks within sites could improve future sampling designs. This research will benefit continuing efforts to monitor, manage, and prevent the establishment of marine invasive species.

Mountains host significantly more data deficient and threatened bat species than lowlands

AbstractMountains harbour one third of the world’s biodiversity and much of it is under increasing anthropogenic pressure. Yet, global assessments of the occurrence, and threat status of most mountain taxa, especially elusive ones are lacking, thereby hindering conservation and research prioritisation. In this study, we synthesise the distribution and conservation status of bats, a species rich taxon on mountains. By using data on geographical and elevational distribution ranges from the International Union for Conservation of Nature (IUCN), we examined bat species richness on mountains, species that predominantly occur in mountains (‘mountain dwelling species’), and those restricted to upper montane and alpine regions within mountains (‘highland dwelling species’). We also used published trait datasets to investigate the traits that are associated with mountain dwelling in bats. Globally, we identified 148 mountain dwelling and 46 highland dwelling bat species. Bat diversity is highest in the Northern Andes and Guiana Highlands. The mountain dwelling nature of bat species was found to be significantly associated with biogeographic realm. Importantly, our results show that mountain dwelling species are proportionately more data deficient than species that predominantly occur in lowlands. Additionally, highland dwelling species are proportionately more threatened than lowland species. Our results highlight a significant dearth of knowledge on mountain dwelling bat species. We conclude that more research is needed for bats specialised on mountain ecosystems. Our results draw attention towards improving the knowledge and protection of bat species that occur predominantly at high elevations across the world.

Regional and local patterns of soil arthropod diversity are explained by different processes in southwest China

Understanding the distribution patterns and underlying mechanisms of community assembly at different spatial scales is crucial for the ecology and conservation of organisms, yet little is known about soil arthropods. In this study, we tested the relative importance of the two hypotheses that could explain soil arthropod distribution patterns at local and regional scales: (1) the habitat heterogeneity hypothesis (spatial complexity and variability of a habitat allow the coexistence of many species), and (2) the more-individuals hypothesis (the amount of resources per se, regardless of its spatial heterogeneity, increases overall soil arthropod abundance and richness). We extensively collected soil arthropods (identified to families or subfamilies) and measured soil physicochemical properties in four forests distributed across latitudes in Yunnan Province, China. We found that soil arthropod abundance and taxon richness increased with increasing latitudes, contrasting with the generally known pattern for plants and aboveground animals. Litter biomass (resources) explained the taxon richness and abundance at the regional scale, which aligned with the more-individuals hypothesis. Other soil physicochemical properties (e.g., Ca, TP, Mg, Mn, and pH) were more important at the local scale, underpinning the habitat heterogeneity hypothesis. However, the relative importance of individual soil properties was highly location-specific, suggesting that the environmental factors operating in one location do not necessarily reflect those operating in others at different latitudes. These findings improve our understanding of the community assembly and ecological processes of soil arthropods at different spatial scales, which is vital for predicting the future of soil biodiversity.

Urban bryophyte floras of Spain: a meta-analysis

ABSTRACT Introduction Bryophytes constitute an important part of the unmanaged plant diversity of urban areas. They represent, directly and indirectly, an important food, shelter and microhabitat-engineering resource allowing the establishment of other organisms, thereby increasing the biodiversity of urban areas. However, their contribution to urban biodiversity is generally overlooked and poorly understood. Methods In this study, we compared pre-existing data from 23 Spanish urban bryophyte floras and used taxon accumulation curves and ordination analyses to reveal emergent patterns related to urban biodiversity in Spain. Key results The compilation of these 23 floras revealed 286 bryophytes represented in urban areas in peninsular Spain and the Balearic Islands, including 2.80% and 3.50% of taxa considered under some threat category at the European and Iberian scales, respectively. Taxon richness and diversity varied greatly across cities and were strongly affected by climatic characteristics and extension of the studied cities. Ordination analyses showed an alignment of the different floras with the geographical location of the cities. Eurosiberian (Atlantic) and eastern and southern cities showed a higher taxon richness compared with cities from central Spain, which showed taxon assemblies comprising the commonest and widespread taxa. We also found that taxon richness was influenced by methodological factors (i.e. sampling intensity and the time the study was done). Conclusions Our study results suggest a need for adequate sampling of habitat heterogeneity within the urban landscape and point to the contribution of bryological knowledge to our understanding of the biodiversity of urban areas.

Nitric oxide shifts the impact of ionic liquid on microbial community structure in rhizosphere of Arabidopsis

ABSTRACT Ionic liquids (ILs) are widely used in various fields due to their excellent properties. Despite their utility, there is limited knowledge regarding the phytotoxic properties of ILs and the mechanisms by which plants develop resistance to them. This is particularly true when considering the role of nitric oxide (NO) in response to ILs stress. Herein, we investigated the mechanism by which endogenous NO reduces the ILs’ phytotoxicity in Arabidopsis from the perspective of rhizosphere microorganisms. We investigated the impact of 1,3-dibutyl imidazole bromide (DIB) on microbial diversity and community in the rhizosphere of Arabidopsis lines with varying endogenous NO levels, using a high throughput sequencing method. DIB did not affect microbial taxon numbers, richness, or evenness; however, it did alter microbial beta diversity and community structure in the rhizosphere of Arabidopsis. Elevated endogenous NO increased fungal richness and evenness, shifted DIB’s impact on microbial community structure, and enriched more resistant species and toxin-decomposing species. These findings suggest a potential mechanism for plants to resist IL stress. Our study not only elucidates the toxicological mechanisms of ILs but also reveals the involvement of NO in plant responses to IL stress, providing valuable insights for future environmental risk assessments and mitigation strategies.

Plankton Resting Stages Distribution in Bottom Sediments along the Confinement Gradient of the Taranto Sea System (Ionian Sea, Southern Italy)

The abundance distribution and species richness of encysted plankton have been investigated in the bottom sediments of the Taranto Marine System (southern Italy) for contributing to the understanding of plankton dynamics in a confined coastal area. This confined area is characterized by four contiguous basins with different degrees of confinement. The investigation was carried out in the fall season with the aim to intercept a period of rich cyst production from the plankton before overwintering. From the analysis of a total of 36 sediment samples, from 12 sample sites, the highest abundance of cysts and species richness were registered in the confined part of the system. A total of 103 cyst morphotypes have been recognized in the whole area, with highest abundances and taxa richness in the most confined stations. These results, suggesting a benthic-pelagic exchange of living matter, more intense in confined environments than in the open sea, highlight the necessity of (i) including the analysis of sediment cyst banks in studies of plankton dynamics, and (ii) to consider the role of confined areas, where the variability of environmental conditions favours a higher planktonic biodiversity in the sediments than in the water column.

Urban biodiversity is affected by human-designed features of public squares

Cities are designed primarily for the benefit of humans but also provide habitat for other species. However, understanding how different components of urban vegetation and other features of urban spaces enable different species or species groups to live in the city remains limited. Here we show that, for the City of Munich, designed features of public urban squares strongly determine the occurrence of different species groups. While taxon richness and abundance increased with increasing ‘greenness’ of the square, different taxa responded to different square features, such as the proportion of lawn, the volume of shrubs and the density of trees, as well as the number of people or pets on these squares. Our results highlight that urban design for human needs affects other species that may cohabit these spaces. Consequently, planning strategies for biodiverse cities that aim to enhance human–nature interactions need to be multifaceted, considering the needs of humans and other taxa to create diverse living cities.

Human impacts mediate freshwater invertebrate community responses to and recovery from drought

Abstract Drought is an increasing risk to the biodiversity within rivers—ecosystems which are already impacted by human activities. However, the long‐term spatially replicated studies needed to generate understanding of how anthropogenic stressors alter ecological responses to drought are lacking. We studied aquatic invertebrate communities in 2500 samples collected from 179 sites on rivers emerging from England's chalk aquifer over three decades. We tested two sets of alternative hypotheses describing responses to and recovery from drought in interaction with human impacts affecting water quality, fine sediment, water temperature, channel morphology, flow and temporal change in land use. We summarized communities using taxa richness, an index indicating tolerance of anthropogenic degradation (average score per taxon, ASPT) and deviation from the average composition. Responses to drought were altered by interactions with human impacts. Poor water quality exacerbated drought‐driven reductions in taxa richness. Drought‐driven deviations from the average community composition were reduced and enhanced at sites impacted by flow augmentation (e.g. effluent releases) and flow reduction (e.g. abstraction), respectively. Human impacts altered post‐drought recovery. Increases in richness were lower at sites impacted by water abstraction and higher at sites with augmented flows, in particular as recovery trajectories extended beyond 3 years. ASPT recovered faster at sites that gained woodland compared to urban land, due to their greater recovery potential, that is, their lower drought‐driven minimum values and higher post‐drought maximum values. Synthesis and applications. We show that communities in river ecosystems exposed to human impacts—in particular poor water quality, altered flow volumes and land use change—are particularly vulnerable to drought. These results provide evidence that management actions taken to enhance water quality, regulate abstraction and restore riparian land use could promote ecological resilience to drought in groundwater‐dominated rivers such as globally rare chalk streams and other rivers of the Anthropocene, as they adapt to a future characterized by increasing climatic extremity.

Response of benthic assemblages to heavy metal contamination from shipbreaking operations in a tropical coastal area

The response of macrobenthic communities to both environmental and anthropogenic pressures serves as a valuable indicator of ecosystem integrity. This study aimed to unravel the benthic community structure, examine the heavy metal contamination status, and explore the response of the microbenthic community to heavy metals in a tropical shipbreaking region. For this, sediment and benthos samples were taken from different sampling stations of the shipbreaking area and the non-shipbreaking sites. The results showed the benthic community consisted of 23 taxa, including Polychaeta, Oligochaeta, Amphipoda, Decapoda, Gastropoda, Bivalvia, and Priapulida, with polychaetes being the predominant group. The benthic community and diversity values were significantly varied between the two sampling sites (p <0.05). Taxa richness was lower in the shipbreaking area, primarily characterized by the dominance of opportunistic benthic groups, particularly Capitella sp. The concentrations of heavy metals (µg. g−1) in the sediment varied within the following ranges: 35.54–258.021 for Zn, 4.84–132.08 for Pb, 22.82–75.25 for Cu, 198.74–764.16 for Mn, 14.57–42.13 for Cr, 4.03–42.23 for Ni, and 3.82–14.85 for Co. Based on concentration levels, Zn, Pb, and Cu were identified as major contaminants with moderate to high potential for adverse effects, particularly evident in the shipbreaking area compared to non-shipbreaking areas. Pollution indices, including enrichment factors and contamination factors, also highlighted contamination by Zn, Pb, and Cu. Among the benthic taxa, Polychaeta demonstrated a high degree of tolerance to elevated concentrations of these heavy metals. Amphipoda density was significantly negatively correlated with Zn, Pb, and Cu concentrations, with significant coefficients of determination (r2= 0.38, p <0.10; r2= 0.64, p <0.01 and r2 = 0.63, p <0.01, respectively). Multivariate analyses (cluster analyses, MDS and CCA) demonstrated both positive and negative relationships among heavy metals and benthic groups. Canonical Correspondence Analysis (CCA) showed the benthic community was negatively correlated with Zn, Pb, and Cu. This finding provided critical insights into the ecological health of aquatic ecosystems, aiding in the development of informed conservation and management strategies.

Benthic macroinvertebrate communities change along a karstic barrage-lake system

Barrage-lake systems are a rare natural phenomenon with specific ecological characteristics that are greatly affected by tufa formation. Our main goal was to investigate benthic macroinvertebrate communities and their longitudinal variations within the lakes arranged in cascades in the Dinaric karst hydrosystem. Each lake within the Plitvice Lakes system studied presented with a distinct community, showing the effects of the barrage-lake system on the macroinvertebrates in these lakes. We observed a downstream decrease in taxa richness, abundance and Shannon diversity index along the longitudinal profile of the studied barrage-lake system. This pattern is most probably a result of decreased organic matter and increased tufa deposition. Overall, our results suggest that the hydrosystem studied represents a sequence of sediment sinks in which lakes retain and accumulate organic matter and fauna. Therefore, each lake acts as a filtering screen and consequently appears to be a small ecosystem. Each lake has its own community characteristics, regardless of the fact that water flows from one lake to the next, connecting them and creating very similar abiotic conditions in each lake along the system.

Using joint species distribution modelling to predict distributions of seafloor taxa and identify vulnerable marine ecosystems in New Zealand waters

Effective ecosystem-based management of bottom-contacting fisheries requires understanding of how disturbances from fishing affect seafloor fauna over a wide range of spatial and temporal scales. Spatial predictions of abundance for 67 taxa were developed, using an extensive dataset of faunal abundances collected using a towed camera system and spatially explicit predictor variables including bottom-trawl fishing effort, using a Joint Species Distribution Model (JSDM). The model fit metrics varied by taxon: the mean tenfold cross-validated AUC score was 0.70 ± 0.1 (standard deviation) for presence–absence and an R2 of 0.11 ± 0.1 (standard deviation) for abundance models. Spatial predictions of probability of occurrence and abundance (individuals per km2) varied by taxon, but there were key areas of overlap, with highest predicted taxon richness in areas of the continental shelf break and slope. The resulting joint predictions represent significant advances on previous predictions because they are of abundance, allow the exploration of co-occurrence patterns and provide credible estimates of taxon richness (including for rare species that are often not included in more commonly used single-species distribution modelling). Habitat-forming taxa considered to be Vulnerable Marine Ecosystem (VME) indicators (those taxa that are physically or functionally fragile to anthropogenic impacts) were identified in the dataset. Spatial estimates of likely VME distribution (as well as associated estimates of uncertainty) were predicted for the study area. Identifying areas most likely to represent a VME (rather than simply VME indicator taxa) provides much needed quantitative estimates of vulnerable habitats, and facilitates an evidence-based approach to managing potential impacts of bottom-trawling.

Biodiversity and conservation of conservation priority fish species in the Nicaraguan volcanic crater lakes

The theory of island biogeography was tested in Nicaraguan volcanic crater lakes, colonized by fish from the older and larger source Nicaraguan Great Lakes. Spearman correlations of ranked molecular phylogenetic diversity in the Midas cichlid species complex (Amphilophus cf. citrinellus) were significant (p ≤ 0.05) or marginally significant (0.05 &lt; p ≤ 0.10) with diversity with crater lake age in three of four data sets tested. Correlations were noted with deepwater area, the product of littoral area and age, and with the product of horizontal and vertical barriers between the crater lakes and the nearest source lakes divided by the product of littoral area and age. By treating the Midas cichlid species complex as a single taxon, ranked fish taxon richness in each lake correlated significantly with lake age, littoral area, and with the product of age and littoral area. These results support the concept that littoral area and lake age may be factors in the colonization of volcanic crater lakes from the source lakes, and the amount of deep water in a lake as well as lake age may be important factors in speciation in the Midas cichlid species complex. Seven species from the crater lakes have been classified as Critically Endangered by the IUCN.

Arctic benthos in the Anthropocene: Distribution and drivers of epifauna in West Greenland

Albeit remote, Arctic benthic ecosystems are impacted by fisheries and climate change. Yet, anthropogenic impacts are poorly understood, as benthic ecosystems and their drivers have not been mapped over large areas. We disentangle spatial patterns and drivers of benthic epifauna (animals living on the seabed surface) in West Greenland, by integrating an extensive beam-trawl dataset (326 stations, 59–75°N, 30–1400 m water depth) with environmental data. We find high variability at different spatial scales: (1) Epifauna biomass decreases with increasing latitude, sea-ice cover and water depth, related to food limitation. (2) In Greenland, the Labrador Sea in the south shows higher epifauna taxon richness compared to Baffin Bay in the north. Τhe interjacent Davis Strait forms a permeable boundary for epifauna dispersal and a mixing zone for Arctic and Atlantic taxa, featuring regional biodiversity hotspots. (3) The Labrador Sea and Davis Strait provide suitable habitats for filter-feeding epifauna communities of high biomass e.g., sponges on the steep continental slope and sea cucumbers on shallow banks. In Baffin Bay, the deeper continental shelf, more gentle continental slope, lower current speed and lower phytoplankton biomass promote low-biomass epifauna communities, predominated by sea stars, anemones, or shrimp. (4) Bottom trawling reduces epifauna biomass and taxon richness throughout the study area, where sessile filter feeders are particularly vulnerable. Climate change with diminished sea ice cover in Baffin Bay may amplify food availability to epifauna, thereby increasing their biomass. While more species might expand northward due to the general permeability of Davis Strait, an extensive colonization of Baffin Bay by high-biomass filter-feeding epifauna remains unlikely, given the lack of suitable habitats. The pronounced vulnerability of diverse and biomass-rich epifauna communities to bottom trawling emphasizes the necessity for an informed and sustainable ecosystem-based management in the face of rapid climate change.

Aquatic Macro-Invertebrate Diversity and Abundance in Eleyele Lake, Ibadan, Oyo State, Nigeria

The availability and quality of water system in 21st century plays a vital role in the growth and survival of all living organisms. Eleyele Lake is a general-purpose water body which supplies water to various communities in Ibadan metropolis. This research aimed to investigate the quality of the water using physico-chemical parameters and their influence on the diversity, abundance and distribution of aquatic macro-invertebrates of the lake. Monthly, sample of water and macro-invertebrates from April to September, 2021 at eight sampling points were done, using standard APHA and Winkler’s methods. Macro-invertebrates collected were identified using standard identification guides. Relationship between physico-chemical parameters and aquatic macro-invertebrates was determined using Pearson’s correlation coefficient (r). Species diversity, taxa richness, evenness and similarity were determined using Simpson, Shannon-Weiner, Margalef, Evennes and Equitablity. A total number of 670 macro-invertebrates belonging to 7 orders namely, Hemiptera (47%), Odonata (20%), Diptera, Coleoptera, Lepidoptera, Trombidiformes and Hygrophila were collected and identified during the study period. Positive correlations occurs between BOD, EC, TDS, Nitrate and Phosphate and Chironomus sp. Also, pH was positively correlated with Lestes sp. and Aeshna sp. while DO have negative correlation with Lethocerus sp., Physa sp. and Lymnaea sp. The physico-chemical parameters and the diversity indices of macro-invertebrates encountered indicated that the lake was moderately polluted and tends toward degradation as a result of indiscriminate discharge of domestic, agricultural and industrial effluents into the Lake. Therefore, proper management of the lake is required to prevent further deterioration.

Topological traits are associated with the prevalence of IGP modules in empirical food webs

Exploring how food webs are assembled from basic modules is charming and crucial for understanding how communities are self-organized. As one of the basic modules, intraguild predation (IGP) consists of a prey being consumed by both an intermediate and a top predator, with the former also being consumed by the latter (thus encompassing both predation and competition). This interaction has been shown to govern food web stability, and therefore underpin the organization of network structures. While some studies have been made in understanding the factors and mechanisms behind the prevalence of IGP modules in food webs, the specific role of food web topological structures in relation to these modules remains largely unexplored and is not well understood. Here, 103 food webs were analyzed, and we found that the number of modules in each food web was largely determined by taxon richness and connectance. After controlling richness and connectance, the specific scale-free pattern and core-periphery structure of empirical food webs explains the higher prevalence of IGP modules in empirical food webs better than by chance. Lastly, the loss of taxa which supported large number of IGP modules would lead to serious damage to food web robustness, indicating the keystone role of these taxa in maintaining food web structure and stability. Our results provide new insight into the assembly of empirical food webs from the perspective of IGP modules.

Soil flooding filters evolutionary lineages of tree communities in Amazonian riparian forests.

Inundations in Amazonian black-water river floodplain result in the selection of different tree lineages, thus promoting coexistence between species. We investigated whether Amazonian tree communities are phylogenetically structured and distributed along a flooding gradient from irregularly flooded forests along streams embedded within upland (terra-firme) forest to seasonally flooded floodplains of large rivers (igapós). Floristic inventories and hydrological monitoring were performed along the Falsino River, a black-water river in the eastern Amazon within the Amapá National Forest. We constructed a presence-and-absence matrix and generated a phylogeny using the vascular plant database available in GenBank. We calculated the standardized values of the metrics of phylogenetic diversity (ses.PD), average phylogenetic distance (ses.MPD), and average nearest-neighbor distance (ses.MNTD) to test whether the history of relationships between species in the community is influenced by inundation. We used the phylogenetic endemism (PE) metric to verify the existence of taxa with restricted distribution. Linear regressions were used to test whether phylogenetic metrics have a significant relationship with the variables: maximum flood height, maximum water table depth, and maximum flood amplitude. The results show that forests subject to prolonged seasonal flooding have reduced taxon richness, low phylogenetic diversity, and random distribution of lineages within communities. On the other hand, terra-firme riparian forests showed higher rates of taxon richness, diversity, and phylogenetic dispersion, in addition to greater phylogenetic endemism. These results indicate that seasonal and predictable soil flooding filters tree lineages along the hydrographic gradient. Different adaptations to root waterlogging are likely requirements for colonization in these environments and may represent an important factor in the diversification of tree lineages in the Amazon biome.

Measurements of soil protist richness and community composition are influenced by primer pair, annealing temperature, and bioinformatics choices.

Protists are a diverse and understudied group of microbial eukaryotic organisms especially in terrestrial environments. Advances in molecular methods are increasing our understanding of the distribution and functions of these creatures; however, there is a vast array of choices researchers make including barcoding genes, primer pairs, PCR settings, and bioinformatic options that can impact the outcome of protist community surveys. Here, we tested four commonly used primer pairs targeting the V4 and V9 regions of the 18S rRNA gene using different PCR annealing temperatures and processed the sequences with different bioinformatic parameters in 10 diverse soils to evaluate how primer pair, amplification parameters, and bioinformatic choices influence the composition and richness of protist and non-protist taxa using Illumina sequencing. Our results showed that annealing temperature influenced sequencing depth and protist taxon richness for most primer pairs, and that merging forward and reverse sequencing reads for the V4 primer pairs dramatically reduced the number of sequences and taxon richness of protists. The data sets of primers that targeted the same 18S rRNA gene region (e.g., V4 or V9) had similar protist community compositions; however, data sets from primers targeting the V4 18S rRNA gene region detected a greater number of protist taxa compared to those prepared with primers targeting the V9 18S rRNA region. There was limited overlap of protist taxa between data sets targeting the two different gene regions (80/549 taxa). Together, we show that laboratory and bioinformatic choices can substantially affect the results and conclusions about protist diversity and community composition using metabarcoding.IMPORTANCEEcosystem functioning is driven by the activity and interactions of the microbial community, in both aquatic and terrestrial environments. Protists are a group of highly diverse, mostly unicellular microbes whose identity and roles in terrestrial ecosystem ecology have been largely ignored until recently. This study highlights the importance of choices researchers make, such as primer pair, on the results and conclusions about protist diversity and community composition in soils. In order to better understand the roles protist taxa play in terrestrial ecosystems, biases in methodological and analytical choices should be understood and acknowledged.

Hierarchical diversity partitioning of microscopic epibiont community on intertidal molluscan shells and inert surfaces over three geographic regions in Japan.

Microscopic epibionts on molluscan shells are a component of the biodiversity of intertidal coastal areas. Because molluscan shells are discrete habitats for the epibiont community, and the molluscan basibionts belong to the local community, epibiont diversity can be evaluated hierarchically by basibiont categories including species. To evaluate the structure of epibiont diversity and effects of taxonomic resolution on the evaluation, epibionts on molluscan shells and inert surfaces were investigated at three geographically distant sites in Japan. In total, 94 species-level taxonomic units of epibionts were obtained from 31 basibiont molluscan species and inert surfaces (plastics and rock chips). The density and the species richness at the site of the lowest latitude were significantly lower than those at the other sites. The epibiont community differed between the three sites, although the major portion of the epibionts were diatoms. Between-site diversity contributed most of the total diversity of the species richness and Simpson diversity in the five levels of the hierarchical partitioning: sample (individual basibiont), basibiont species (molluscan species), surface group (bivalves, chitons + limpets, and globose gastropods), site, and the total. The taxonomic resolution did not markedly affect the variability of communities between the three sites, although the taxon richness was reduced to 51 in the genus-level analysis. The lower taxonomic resolution (genus level); however, increased the contribution of the within-sample and decreased the contribution of β diversities at the higher hierarchies, leading to a possible overestimation of biotic homogenization between the communities.

Invertebrate Responses to Large- and Small-Scale Drivers in Coastal Phragmites australis Beds in the Northern Baltic Sea

Phragmites australis is a common helophyte, covering much of the sheltered and shallow soft bottoms along the coasts of the Baltic Sea. Despite the expansion of P. australis over the past decades, there is little information on aquatic macroinvertebrates within P. australis beds. In this study, we examined the effect of large-scale (wave exposure, nutrients) and small-scale (distance from the seaward edge, live and dead stalk density, epiphyte and rhizome biomass) drivers on the density, taxa richness, diversity, and community structure of epifauna and infauna in monospecific P. australis beds around the Åland Islands and the Archipelago Sea. We found that higher wave exposure and nutrient levels generally supported higher epi- and infauna abundance and taxa richness. The effects on Shannon–Wiener diversity were less evident apart from an increase of the infauna diversity in the Archipelago Sea with increasing nutrient levels. On a local scale, the distance from the seaward edge, live and dead stalk density, and epiphyte biomass had varying effects on both epi- and infauna communities in the different regions. Rhizome biomass had no effect on either the epi- or infauna abundance, taxa richness, or diversity. Furthermore, according to existing studies, other habitats, e.g., Zostera marina meadows, Fucus vesiculosus belts, and vegetated soft-bottomed shallow bays, are generally characterized by more abundant fauna, except for the infauna, which had a higher density in P. australis beds than in vegetated soft-bottomed shallow bays. P. australis are a widespread, expanding, and understudied habitat with an important role in supporting coastal biodiversity.