Zooplankton communities exhibit high temporal variability driven by changing environmental conditions and trophic interactions. Multivariate analyses are widely used to characterize these dynamics, yet many long-term freshwater datasets are sparse or irregular, and few studies have compared how different methods shape ecological interpretation. We applied three complementary approaches-unconstrained non-metric multidimensional scaling (NMDS), constrained ordination (RDA/dbRDA), and indicator species analysis (ISA)-to a seven-year zooplankton dataset from a eutrophic reservoir to evaluate community variability. All methods revealed broadly consistent temporal patterns, with similar community dynamics among seasons and years. RDA/dbRDA identified several environmental drivers of the zooplankton community, including Secchi depth, total phosphorus, and Schmidt stability, while ISA highlighted Bosmina and Ceriodaphnia as important indicator taxa based on interannual density patterns. Together, these results demonstrate that diverse multivariate methods can provide complementary insights and longer-term, sporadic plankton time series can yield robust ecological inference when analyzed in an integrative framework.

Invasions by new host species could potentially affect native symbionts associated with native hosts. Effects of invading hosts can be either negative or positive depending on host competence. Three native crayfish species (Cambarus spp.) in the New River in North Carolina, USA, may host up to seven species of ectosymbiotic worms (Branchiobdellidans). Branchiobdellidans require crayfish for successful reproduction. Faxonius cristavarius, an invasive crayfish in the New River, is a noncompetent host for native branchiobdellidans and removes colonizing worms. The distributions of three native crayfish species now overlap with F. cristavarius in the New River. We collected crayfish at various locations in the New River to determine the diversity and abundance of worms on native Cambarus spp. and F. cristavarius. Sampled sites ranged from 0 to 100% invaded by F. cristavarius. There were significant reductions in branchiobdellidan abundance and richness on native Cambarus spp. in response to an increasing relative abundance of F. cristavarius. We also conducted an experiment to determine whether the presence of F. cristavarius affected the abundance of worms on the native Cambarus robustus. The control treatment (Cr/Cr) contained a single C. robustus stocked with 5 worms paired with an unstocked C. robustus; a second treatment contained a single, stocked C. robustus paired with an unstocked F. cristavarius (Cr/Fc). Significantly fewer worms remained in the Cr/Fc treatment. Our research shows that invasions by non- or low competent hosts can have significant, negative effects on native symbiont communities. Similar negative effects on native symbionts may occur in other host invasions.

ABSTRACT Crayfish are keystone species and ecosystem engineers in aquatic ecosystems, and many species require conservation to support their continued persistence. Unfortunately, managers often lack basic data needed to make effective conservation decisions. This lack of data is especially true within the New River catchment, United States, where there are 12 known crayfish species, but it is unclear which of those species are native to the catchment, and there is scant ecological and life history data available for many species. Therefore, our objective was to investigate coarse‐scale occurrence drivers of crayfishes in the New River catchment. We used generalized linear mixed effects models to predict occurrence of eight taxa based on instream and landscape‐scale environmental data and biotic interactions. We found that increasing anthropogenic disturbance led to declines in Faxonius spp. (either Faxonius obscurus or Faxonius sanbornii but could not be identified to species) and Cambarus smilax . In contrast, disturbance had a positive relationship only with Faxonius cristavarius . The presence of F. cristavarius was negatively associated with most species. Embeddedness, substrate, per cent riffle, stream size and lithology were additional variables that were related to crayfish occurrence. Our results reveal that increasing human‐mediated changes and invasive crayfish species threaten the persistence of native crayfishes in the New River catchment.

Recently, there has been an effort to view the study of symbiosis through the lens of community ecology. Hosts can be viewed as patches in a symbiont metacommunity, and host ontogenetic change can alter the properties of patches occupied by symbionts. We used a freshwater cleaning symbiosis between a population of Conhaway crayfish Cambarus appalachiensis and their community of ectosymbiotic branchiobdellidan worms to explore how an ontogenetic change in host molting can act as a disturbance in symbiont community assembly. Based on a year‐long survey of crayfish hosts and their symbiont communities, host molting acted as a disturbance that reset the process of symbiont community assembly. Crayfish that had recently molted had a symbiont community that was more similar to smaller crayfish. This dynamic is likely driven by a competition–colonization tradeoff between the species in the symbiont community, with smaller symbionts having better colonization ability, and larger symbionts having better competitive ability. The richness of the symbiont community was lowest on crayfish that molted very recently, supporting the idea that the symbiont communities on recently molted crayfish are composed of the early colonizing species that characterize the symbiont communities on smaller crayfish. On larger crayfish that had not molted recently, the richness of the symbiont community was higher, while it was highest on larger crayfish that had molted somewhat recently. This suggests that the disturbance caused by molting was interacting with competition–colonization tradeoffs among the symbionts to determine the composition of the ectosymbiotic community. Our results show that host‐related disturbances can be an important part of community assembly in symbiont communities, and ectosymbioses involving a molting invertebrate host provide a unique tool to study the processes underlying community assembly in symbiotic communities.

Mutualisms are common interactions that involve a diverse array of taxa. An important aspect in the study of mutualisms is determining the mechanisms that underlie benefits in survival, growth and reproduction of the partner species involved. Crayfish are engaged in mutualisms with ectosymbiotic worms called branchiobdellidans. These worms benefit by using their crayfish hosts as safe habitat and sites for feeding and reproduction. Some of these worm species can improve crayfish survival and growth. We hypothesized that the worms influenced crayfish survival and growth by cleaning their gills of debris and fouling biota and that this cleaning would increase rates of host gas exchange and ammonia excretion. Using surveys and experiments, we examined the effect of the worms on crayfish ammonia excretion and oxygen consumption. There were positive effects of increasing worm density on ammonia excretion by crayfish hosts in both our survey and experiment. No effect of worm density was observed on oxygen consumption in either our survey or experiment. However, molt status of the surveyed crayfish (intermolt/premolt vs. recently molted) did affect oxygen uptake. Recently molted crayfish, which should have gill epithelia largely free of fouling organisms and debris, had higher levels of dissolved oxygen uptake than intermolt/premolt crayfish which should have had higher levels of gill fouling. Increased ammonia excretion at moderate worm densities likely underlies the increased survival and growth responses observed at these densities in previous experiments. Increased growth of crayfish hosting worms probably influences the impacts of these crustaceans on the benthic communities they occupy.

Zooplankton play an integral role as indicators of water quality in freshwater ecosystems, but exhibit substantial variability in their density and community composition over space and time. This variability in zooplankton community structure may be driven by multiple factors, including taxon-specific migration behavior in response to environmental conditions. Many studies have highlighted substantial variability in zooplankton communities across spatial and temporal scales, but the relative importance of space vs. time in structuring zooplankton community dynamics is less understood. In this study, we quantified spatial (a littoral vs. a pelagic site) and temporal (hours to years) variability in zooplankton community structure in a eutrophic reservoir in southwestern Virginia, USA. We found that zooplankton community structure was more variable among sampling dates over 3 years than among sites or hours of the day, which was associated with differences in water temperature, chlorophyll a, and nutrient concentrations. Additionally, we observed high variability in zooplankton migration behavior, though a slightly greater magnitude of DHM vs. DVM during each sampling date, likely due to changing environmental conditions. Ultimately, our work underscores the need to continually integrate spatial and temporal monitoring to understand patterns of zooplankton community structure and behavior in freshwater ecosystems.

Organismal invasions have repeatedly been cited as a driving force behind the loss of biodiversity. Unlike many other impacts of invasion, the effect of invasion on native symbiont communities has received less attention. The introduction of invasive hosts presents a potential opportunity to native symbionts; invasive hosts could benefit native symbionts through providing a novel host environment that improves symbiont fitness relative to their fitness on native hosts. Alternatively, invasive hosts could noncompetent hosts for native symbionts, resulting in negative impacts on native symbiont abundance and diversity. Crayfish in the northern hemisphere host diverse assemblages of obligate annelid symbionts (P: Anellida, O: Branchiobdellida). Two invasive crayfish hosts in the genus Faxonius have been introduced and are interacting with the native crayfish hosts and their symbionts in three watersheds in western Virginia, USA. Previous studies suggest that the invasive host F. cristavarius is a less competent host for symbionts compared to native hosts in the genus Cambarus. We carried out an extensive survey in these watersheds to determine impacts of varying degrees of invasion on branchiobdellidan abundance and diversity. We also conducted a complementary host replacement experiment to investigate how increases in the relative abundance of invasive hosts contributes to observed patterns of symbiont abundance and diversity in the field. In our survey, as the proportion of invasive hosts at a site increased, branchiobdellidan abundance and diversity declined significantly. In the experiment, the worms dispersed onto both native and invasive hosts. As the percentage of noncompetent F. cristavarius hosts increased, the survival of branchiobdellidans declined. Both symbiont survival and opportunities for successful dispersal are reduced as this noncompetent invasive host progressively displaces native hosts, which imperils the integrity of native host-symbiont systems. Given that many native hosts accrue significant fitness benefits from their relationships with native symbionts, including hosts in our study system, losses of beneficial symbionts may produce a positive feedback loop that decreases invasion resistance of native species, exacerbates the effects of invasions, and presents a major conservation issue in invaded systems.

Although effective contraceptives are crucial for preventing unintended pregnancies, evidence suggests that their use may perturb the female genital tract (FGT). A comparative analysis of the effects of the most common contraceptives on the FGT have not been evaluated in a randomized clinical trial setting. Here, we evaluated the effect of three long-acting contraceptive methods: depot medroxyprogesterone acetate(DMPA-IM), levonorgestrel(LNG) implant, and a copper intrauterine device (Cu-IUD), on the endocervical host transcriptome in 188 women from the Evidence for Contraceptive Options and HIV Outcomes Trial (ECHO) trial. Cu-IUD usage showed the most extensive transcriptomic changes, and was associated with inflammatory and anti-viral host responses. DMPA-IM usage was enriched for pathways associated with T cell responses. LNG implant had the mildest effect on endocervical gene expression, and was associated with growth factor signaling. These data provide a mechanistic basis for the diverse influence that varying contraceptives have on the FGT.

Despite knowing the threats posed by biological invasions, governments struggle to effectively prevent and control invasive species. To mitigate the negative impacts of invasive species, a coordinated response, grounded in the best available science and attentive to the dynamics of policymaking, is critical. To evaluate patterns in state policies, we conducted a comprehensive survey of invasion-related laws and regulations in 21 eastern US states. We identified 706 policy chapters and found that most were enacted after 1970. The policies on terrestrial invasions outnumbered those for aquatic habitats, although the states farther east generally had a higher proportion of aquatic policies. Across all of the chapters, we identified 1200 unique species, 523 of which are listed as introduced or invasive. The state policies were inconsistent in which invasive species they name, especially for invertebrate taxa. Our conclusions indicate that effective, coordinated actions on invasives require improving communication, collaboration, and data sharing within and across domains.

In their recent TREE article, Sax et al. [ 1. Sax D.F. et al. Valuing the contributions of non-native species to people and nature. Trends Ecol. Evol. 2022; 37: 1058-1066 Abstract Full Text Full Text PDF PubMed Scopus (12) Google Scholar ] call for less biased research on non-native species by encouraging scientists to evaluate the positive impacts of non-native species alongside the negative. We agree that scientists should recognize the highly nuanced roles species play in ecosystems, regardless of origin. However, we also believe that it is essential to incorporate perspectives outside science in discussions on species’ impacts. By primarily addressing invasion and conservation scientists, Sax et al. overlook the broader social and political elements involved in assessing the impacts of non-native species. We contend that (i) holistic assessment of non-native species in ecosystems requires increased research from outside the natural sciences and (ii) assigning value to non-native species needs to be a collaborative enterprise involving diverse stakeholders, not just natural or social scientists. Embracing the diversity of perspectives concerning the presence and impact of non-native species can facilitate effective management and policy interventions (e.g., [ 2. Cordell S. et al. Species home-making in ecosystems: toward place-based ecological metrics of belonging. Front. Ecol. Evol. 2021; 9726571 Crossref Scopus (2) Google Scholar ]).

Background The cervicovaginal mucosa is inhabited by an ecosystem of bacteria, fungi and viruses, which likely interact with each other. The vaginal virome may influence vaginal immunity directly, or though modulation of the bacterial component via bacterial-phage dynamics. These interactions may play an important role in sexual and reproductive health outcomes. However, it is predicted that over 60% of the human DNA virome has not yet been identified, and the RNA virome is even less explored, nor has the impact of HIV on the vaginal virome composition been described. Methods We optimised viral particle extraction from vaginal swabs. We then optimised a Sequence Independent Single Primer Amplification (SISPA) approach to enable deep sequencing of the viral metagenome that decreases the GC and genome size bias introduced by commonly used methods such as Multiple Displacement Amplification and Rolling Circle Amplification, while also yielding a greater diversity of near-complete metagenome-assembled genomes. Results SISPA was able to recapitulate almost exactly the relative abundance of a viral mock community. Storing swabs in universal transport media (UTM) directly after collection and treating the sample with a 18G needle prior to viral particle extraction resulted in the greatest yield of viral nucleic acid and subsequent read depth, over storing swabs dry or in a 1:1 dilution of UTM and SM buffer. We have applied this method to vaginal swabs from Sub-Saharan African women with and without HIV. Conclusion This work lays the ground work for project TMA2020CDF-3192, which will assess the interaction of vaginal virome and bacteriome in pregnant women with HIV in sub-Saharan Africa and risk of preterm birth.

Other than for papillomaviruses, there is a paucity of whole-genome sequences for bacteriophages and eukaryote-infecting viruses isolated from the female genital tract. Here, we report the genome sequences of 16 microviruses, 3 anelloviruses, 2 polyomaviruses, 1 genomovirus, and 1 caudovirus that were identified in vaginal secretion samples from adolescents in South Africa.

Digital specimens collected by community members are a largely untapped source of entomological data. By mining and curating data from photo observations uploaded to online community data repositories, researchers can utilize this wealth of information to address questions about predator–prey interactions, phenotypic variation within species, plant–pollinator interactions, and a host of other topics. We mined data from photo observations on the community science website iNaturalist to investigate patterns in host plant availability and affiliation by 2 species of soldier beetles, Chauliognathus marginatus (F.) and Chauliognathus pensylvanicus (De Geer). Chauliognathus marginatus was observed with white flowers more than expected based on their potential availability, while C. pensylvanicus was observed with yellow flowers over all other flower colors and more than expected based on their potential availability. Communities of flowers available to, and observed with, C. marginatus and C. pensylvanicus differed significantly at the family and genus levels. To our knowledge, this is the first study to utilize a dataset mined and curated from community science photo observations to address species-specific behavior and ecology questions. With appropriate study design and analytical methods, these types of data could prove invaluable in future investigations of a variety of entomological and ecological questions.

When investigating metacommunity dynamics, functional differences among species are often assumed to be as important as environmental differences between sites in determining beta-diversity. However, few studies have examined the influence of functional diversity on beta-diversity. We examine the relative importance of regional functional diversity partitioned by niche dimensions and environmental variation in structuring taxonomic beta-diversity of stream fishes using a large dataset of stream fish assemblages (hereafter, simply beta-diversity). We predicted that both functional diversity and environmental variation play a role in determining beta-diversity. We tested this prediction by modelling the patterns of stream fish beta-diversity as a function of environmental variation, functional diversity and gamma-richness across 10,220 sites for 329 fish species using a series of conceptual path models. Environmental variation consistently affected beta-diversity across all models, whereas functional diversity and gamma-richness influenced beta-diversity only in some models. We show that including relevant trait differences among species in path models can improve their ability to explain beta-diversity, suggesting that functional traits influence beta-diversity. The ability of path models to explain beta-diversity varied depending on the trait grouping included in the model, demonstrating that specific path models representing different niche dimensions can improve the ability of a model to explain beta-diversity. In addition, parsing traits into different niche dimensions revealed alternative patterns of functional diversity-beta-diversity relationships that otherwise would have been missed. The selection of relevant traits and linked niche dimensions is critical for detecting relationships between functional diversity and beta-diversity. Using traits associated with different niche dimensions allows for the identification of niche dimensions most strongly associated with species sorting and the detection of patterns missed by focusing on a single niche dimension. Determining the niche dimensions that influence beta-diversity could provide insights into the processes driving biodiversity and metacommunity dynamics, improving our ability to conserve or restore aquatic communities.

We examined the hypothesis that adapting to ecosystem change on working landscapes can be enhanced by supporting the place-based stewardship values of landowners. On the basis of responses to a survey of more than 500 landowners across a landscape dominated by working lands, we clustered landowners into five groups based on their sense of place meanings. Relationships with the land are differentiated by the degree to which an owner’s land makes positive contributions to well-being and the degree to which the land supports livelihoods. Positive contributions to well-being are related to stronger stewardship-oriented management styles, yet a combination of well-being and livelihood dependence is most closely related to increased sensitivity to ecosystem transformation. In a social–ecological system dominated by private lands, understanding an individual's relationship with the land is central to understanding adaptive capacity and for identifying policy options to successfully respond to ecological transformation.

The interaction between cervicovaginal virome, bacteriome and genital inflammation has not been extensively investigated. We assessed the vaginal DNA virome from 33 South African adolescents (15–19 years old) using shotgun DNA sequencing of purified virions. We present analyses of eukaryote-infecting DNA viruses, with a focus on human papillomavirus (HPV) genomes and relate these to the vaginal bacterial microbiota (assessed by 16S rRNA gene sequencing) and cytokines (assessed by Luminex). The DNA virome included single-stranded (Anelloviridae, Genomoviridae) and double-stranded DNA viruses (Adenoviridae, Alloherpesviridae, Herpesviridae, Marseilleviridae, Mimiviridae, Polyomaviridae, Poxviridae). We identified 110 unique, complete HPV genomes within two genera (Alphapapillomavirus and Gammapapillomavirus) representing 40 HPV types and 12 species. Of the 40 HPV types identified, 35 showed positive co-infection patterns with at least one other type, mainly HPV-16. HPV-35, a high-risk genotype currently not targeted by available vaccines, was the most prevalent HPV type identified in this cohort. Bacterial taxa commonly associated with bacterial vaginosis also correlated with the presence of HPV. Bacterial vaginosis, rather than HPV, was associated with increased genital inflammation. This study lays the foundation for future work characterizing the vaginal virome and its role in women’s health.

We reviewed the timing of the peak rate of emergence for 15 problematic weed species as well as ways to use this knowledge to improve control. Much of the previous literature modeled emergence based on growing-degree-days. For these models, we input average temperature data from several zones of Northeast USA. Within species, model-predicted peak emergence in the warmest and coolest zones differed by an average of 39 days. Also within species, there was some variation between models, likely reflecting different conditions in study locations and population-level differences that will need to be addressed in future modelling efforts. Summarizing both observed and modelled results, emergence typically peaked early-season for barnyardgrass, Canada thistle, common lambsquarters, common ragweed, giant foxtail, large crabgrass, perennial sowthistle, and smooth crabgrass. Emergence typically peaked mid-season for hairy galinsoga, mouseear chickweed, and red sorrel. Emergence typically peaked late-season for annual bluegrass. Several species emerged in a protracted manner, including common chickweed, quackgrass, and redroot pigweed. With this improved knowledge, farmers may target key problematic species of a particular field in several ways. Weed seedling control efforts can be timed at the highest densities or most vulnerable phenological stage. Residual herbicides and suppressive mulches can be timed to maximize effectiveness prior to their breakdown. And if management flexibility allows, crop selection and associated planting dates may be adjusted to improve crop competition or facilitate seedbank depletion through timely bare fallow periods. Such improvements to weed management based on timing of emergence will likely become even more impactful as predictive model reliability continues to improve.

Meta-approaches to understanding diversity, including meta-populations and meta-communities, have created a paradigm shift in ecological research, including in stream ecosystems. Both of these frameworks emphasize the major role that organismal dispersal plays in generating and maintaining biodiversity patterns because dispersal links processes at local scales to processes at larger spatial scales. Fundamental to the application of meta-approaches is an understanding of dispersal. Ecologists working in stream systems use various methods to measure or estimate the dispersal of aquatic organisms. More direct measures include mark-recapture techniques and the use of various nets and traps. Due to the difficulty of directly monitoring the dispersal of aquatic organisms, particularly smaller taxa, organismal-based dispersal proxies such as traits-based approaches and population genetics can be used to infer dispersal patterns. Graph-based proxies that rely on the spatial distribution of sampling sites can also be used to infer dispersal in stream networks. While experimental approaches—including the direct manipulation of dispersal—have been employed less often than observational approaches, they have been able to mechanistically link dispersal rates and patterns to patterns in observed biodiversity. Likewise, theoretical approaches that include mathematical and simulation modeling have been able to conduct in silico experiments to test scenarios that are impractical or impossible to conduct in real-world systems. Here we provide a brief introduction to these techniques, highlight some of the insights that they have enabled, and discuss their importance in bringing meta-approaches to the study of stream ecosystems. In this chapter, we provide an introduction to the study of dispersal from the perspective of its importance for meta-approaches in stream ecology that briefly touches on the conceptual importance of studying dispersal and on the techniques used to measure or estimate dispersal. In reviewing literature to include in this article, we chose to focus on fine-scale work performed at a maximum scale of a few adjacent watersheds because these studies best illustrate the approaches and techniques for the study of dispersal. However, a considerable amount of work also exists that applies meta-population and meta-community theory to large-scale biogeographic biodiversity patterns. Thus, our work here is not meant to be an exhaustive review of the literature on dispersal in stream networks, but to serve as an introduction to the various techniques used to understand the dispersal of stream organisms. Additionally, while the focus of this article is mainly dispersal in stream meta-populations and meta-communities, these are relatively new fields of study. Multiple foundational papers on dispersal in stream networks that we included here do not directly address meta-population or meta-communities. These older works are, however, crucial for an introduction to the topic, and the study of dispersal would be much diminished without the groundwork that these works provided.