SEARCH · PubMed Health

Results for “Invertebrates”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

PubMed2026

Novelty, diversity, and genetic dark matter in enterococci of invertebrates.

Enterococci appear to have originated in the guts of early terrestrializing arthropods and invertebrates over 425 million years ago-hosts that are now highly diverse and widespread in nature today. Yet most knowledge of the genus comes from human infection-associated lineages with genomes swollen by the recent accretion of foreign DNA conveyed by mobile elements. Because invertebrates dominate terrestrial animal diversity and biomass, they would be predicted to constitute a major but little-explored reservoir of enterococcal diversity. We therefore systematically examined Enterococcus association and species diversification in invertebrate hosts of the comparatively natural, isolated, but well-characterized environment of the Azorean island of Terceira. Over 100 invertebrate specimens were examined for associated enterococci, which were taxonomically classified by whole-genome sequencing. Supporting the existence of a large pool of uncharacterized enterococci and Enterococcus-adapted genes, 40% (eight of 20) of the Enterococcus species identified were either undescribed, including four candidate new species described here, or very recently discovered. In contrast, control isolates from vertebrates were exclusively of known species typical of sampling elsewhere, discounting geographic isolation as a main driver of the novelty observed. Further, because of the abundance of E. casseliflavus and E. flavescens in this collection, we obtained the resolution necessary to quantify the divergence and decipher the drivers of speciation in the controversial division between these naturally vancomycin-resistant species. These findings provide robust support for the existence of a large pool of new species and unexplored adaptive traits in invertebrate-associated enterococci-diverse environmental survival traits optimized for expression in an enterococcal background, and well positioned for transmission into human-associated enterococcal strains.IMPORTANCEEnterococci are auxotrophic gut-associated bacteria that co-evolved with their terrestrial hosts over many eons. In the last 75 years-the "antibiotic era"-E. faecalis and E. faecium gained genes for antibiotic resistance and enhanced virulence, emerging as leading causes of multidrug-resistant infection. Little is known about the source of those genes or the pathway by which they entered human-associated strains. A recent global survey suggested a potentially large repository of uncharacterized genetic diversity in the enterococci of invertebrates. We directly tested this prospect by examining enterococci of invertebrate hosts in a largely natural and pastoral environment. Our findings provide clear evidence that invertebrates naturally harbor vast unexplored enterococcal diversity. Moreover, associations are likely driven by intrinsic host selection factors rather than geographic isolation. This expands our knowledge of Enterococcus biodiversity, including the identification of four novel species, identifying a vast reservoir of enterococcal genes available to species that colonize and infect humans.

Animals↗

PubMed2025

Pseudoalteromonas is a novel symbiont of marine invertebrates that exhibits broad patterns of phylosymbiosis.

Despite growing insights into the composition of marine invertebrate microbiomes, our understanding of their ecological and evolutionary patterns remains poor, owing to limited sampling depth and low-resolution datasets. Previous studies have provided mixed results when evaluating patterns of phylosymbiosis between marine invertebrates and marine bacteria. Here, we investigated potential animal-microbe symbioses in Pseudoalteromonas, an overlooked bacterial genus consistently identified as a core microbiome taxon in diverse invertebrates. Using a pangenomic analysis of 236 free-living and invertebrate-associated bacterial strains (including two new nematode-associated isolates generated in this study), we confirm that Pseudoalteromonas is a novel symbiont with substantial evidence of phylosymbiosis across at least three marine invertebrate phyla (e.g., Nematoda, Mollusca, and Cnidaria). Patterns of symbiosis were consistent irrespective of geography (including in Antarctica), with FISH images from nematodes indicating that bacterial symbionts form biofilms in the mouth and esophagus. The evolutionary history of Pseudoalteromonas is marked by substantial host-switching and lifestyle transitions, and host-associated genomes suggest that these bacteria are facultative symbionts involved in nutritional mutualisms. In marine environments, we hypothesize that horizontally-acquired symbionts may have co-evolved with invertebrates, using host mucus as a physical niche and food source, while providing their animal hosts with Vitamin B, amino acids, and bioavailable carbon compounds in return.

Marine Invertebrates↗

PubMed2026

DNA methylation-based ageing in a deuterostome invertebrate: an epigenetic clock for the crown-of-thorns seastar (Acanthaster cf. solaris).

Accurate and reliable ageing tools are essential for wildlife conservation and management. While DNA methylation has emerged as a promising tool for age estimation in vertebrates, its application to invertebrates remains contested and has been limited to arthropods. Here, we develop an epigenetic clock for the Pacific crown-of-thorns seastar (CoTS; Acanthaster cf. solaris), a destructive coral predator contributing to habitat degradation across Indo-Pacific reefs. Using Oxford Nanopore Technologies, we generated whole-genome DNA methylation profiles across five age groups and identified 1910 CpG sites with methylation patterns significantly associated with age. We then fitted age prediction models using elastic net regression and evaluated predictive performance with leave-one-out cross-validation (LOOCV), achieving a mean absolute error of 0.31 ± 0.22 years, corresponding to 4-6% of the CoTS lifespan (5-8 years). This accuracy suggests the potential to differentiate annual cohorts, supporting future management-relevant inference. To facilitate practical implementation, we constructed an optimized epigenetic clock from 14 CpG sites consistently selected across LOOCV iterations. Our results demonstrate that DNA methylation-based age estimation is feasible in a deuterostome invertebrate, extending epigenetic ageing approaches beyond arthropods and establishing their potential to advance age determination and management in invertebrates that lack reliable ageing methods.

Animals↗

PubMed2025

The ecology, evolution, and physiology of Cardinium: a widespread heritable endosymbiont of invertebrates.

Candidatus Cardinium hertigii (Cardinium) are maternally transmitted obligate intracellular bacteria found in a wide range of invertebrate hosts, including arthropods and nematodes. Infection with Cardinium has substantial consequences for host biology, with many strains manipulating host reproduction to favor symbiont transmission by (i) feminizing male hosts, (ii) altering host sex allocation, (iii) inducing parthenogenesis, or (iv) causing cytoplasmic incompatibility. Other Cardinium strains can confer benefits to their host or alter host behavior. Cardinium-modified host phenotypes can result in selective sweeps of cytological elements through host populations and potentially reinforce host speciation. Cardinium has potential for applications in controlling arthropod pest species and arthropod-vectored disease transmission, although much remains to be explored regarding Cardinium physiology and host interactions. In this review, we provide an overview of Cardinium evolution and host distribution. We describe the various host phenotypes associated with Cardinium and how biological and environmental factors influence these symbioses. We also provide an overview of Cardinium metabolism, physiology, and potential mechanisms for interactions with hosts based on recent studies using genomics and transcriptomics. Finally, we discuss new methodologies and directions for Cardinium research, including improving our understanding of Cardinium physiology, response to environmental stress, and potential for controlling arthropod pest populations.

Symbiosis↗

PubMed2024

Vertebrate and invertebrate animal infection models of Candida auris pathogenicity.

Candida auris is an emerging fungal pathogen with several concerning qualities. First recognized in 2009, it has arisen in multiple geographically distinct genomic clades nearly simultaneously. C. auris strains are typically multidrug resistant and colonize the skin much better than most other pathogenic fungi; it also persists on abiotic surfaces, enabling outbreaks due to transmission in health care facilities. All these suggest a biology substantially different from the 'model' fungal pathogen, Candida albicans and support intensive investigation of C. auris biology directly. To uncover novel virulence mechanisms in this species requires the development of appropriate animal infection models. Various studies using mice, the definitive model, are inconsistent due to differences in mouse and fungal strains, immunosuppressive regimes, doses, and outcome metrics. At the same time, developing models of skin colonization present a route to new insights into an aspect of fungal pathogenesis that has not been well studied in other species. We also discuss the growing use of nonmammalian model systems, including both vertebrates and invertebrates, such as zebrafish, C. elegans, Drosophila, and Galleria mellonella, that have been productively employed in virulence studies with other fungal species. This review will discuss progress in developing appropriate animal models, outline current challenges, and highlight opportunities in demystifying this curious species.

Animals↗

PubMed2026

Di-, tri-, and tetranucleotide frequencies covary with lifespan and genome size across protostome invertebrates.

Animal lifespans span orders of magnitude, yet how genome sequence covaries with lifespan remains poorly characterized outside vertebrates. Although promoter CpG density has been linked to vertebrate longevity due to its gene-regulatory function through DNA methylation, it is unclear whether such patterns are promoter- and CpG-specific, or if they reflect broader sequence evolution. We curated maximum lifespan estimates for 466 protostome species spanning eight phyla with available genome assemblies and quantified mono-, di-, tri-, and tetranucleotide composition across whole genomes, intergenic regions, and six gene-associated regions (two upstream regions, exons, introns, and two downstream regions) defined using Benchmarking Universal Single-Copy Orthologs. Dinucleotide observed/expected ratios showed significant associations with lifespan and genome size in different ways. Lifespan-associated motifs were most pronounced in gene-associated non-coding regions, especially in introns and downstream regions, whereas genome-size effects were strongest in whole-genome and intergenic sequence. Tri- and tetranucleotide observed/expected ratios broadly recapitulated this regional organization. In contrast, GC content was not associated with lifespan across regions, indicating that the observed signals are not explained by mononucleotide composition but instead by how those nucleotides are arranged into short sequence motifs. These results suggest that lifespan and genome size show distinct but overlapping associations with regional sequence composition across invertebrate species and that lifespan-associated motif evolution extends beyond vertebrate promoter methylation architectures.

CpG density↗

PubMed2026

Invertebrate miRNA pva-small RNA-11881/pva-miR-11881 as a potential RNA-based therapeutic against white spot syndrome virus in infected shrimp.

Small RNAs and microRNAs (miRNAs) play diverse roles in host virus interactions and hold promise for therapeutic applications. An uncharacterized shrimp miRNA with potent activity against white spot syndrome virus (WSSV), a major double-stranded DNA pathogen in aquaculture, was identified and characterized. Among the 1,239 differentially expressed unannotated small RNAs in Penaeus vannamei hemocytes, one of the most strongly downregulated candidates, termed pva-small RNA-11881 or pva-miR-11881, was predicted to target multiple WSSV genes. A pva-small RNA-11881/pva-miR-11881 isomir that originates from the 5' untranslated region of a host lipase 3-like gene was identified. Its primary transcript contains Drosha and Dicer processing sites, and the precursor exhibits canonical pre-miRNA features. In vivo administration of its primary transcript, pva-pri-miR-11881, significantly reduced WSSV copy number and improved shrimp survival. Mechanistically, pva-miR-11881 directly suppresses crucial WSSV genes WSSV004, WSSV164, and WSSV419 and modulates the host immune response against WSSV infection by enhancing phenoloxidase activity, thereby reducing apoptosis and necrosis, and promoting caspase-1-mediated cell death. These findings reveal that the pva-miR-11881 in P. vannamei holds strong potential as a biotherapeutic agent for managing viral diseases in shrimp.

Animals↗

PubMed2026

Bycatch in a bottle: what taxa are recoverable from metabarcoding DNA in historical invertebrate collection preservative fluid?

Natural history museum collections are invaluable repositories of biodiversity, offering insights into life on Earth. Genomic approaches provide powerful tools to characterize biodiversity in these collections. However using these collections for genomics without damaging specimens is a challenge. Here, we develop and test non-destructive DNA metabarcoding methods to capture biodiversity from the preservative fluids of archived insect collections ('Bycatch'). We optimized workflows for extracting and amplifying the partial CO1 locus (CO1) and fungal ITS1 locus from ethanol-based preservative fluids, validating ethanol preparation methods, comparing DNA extraction kits, and refining PCR protocols. Our results demonstrate that from museum collections with low DNA yields, CO1 and fungal ITS1 loci can often be recovered from preservative fluids, and we present detailed methodology and workflows. We test metabarcoding success to recover taxa in several museum collections ranging in age and storage condition. This is to support the State of California's effort to catalog and sequence all insects and fungi, building baselines of California biodiversity with help from museum collections. Lastly, we investigate the complementarity of metabarcoding water versus ethanol and morphological identifications aimed to capture benthic macroinvertebrate biodiversity in streams. Our findings highlight that DNA metabarcoding of the preservative fluid is a non-destructive tool for capturing biodiversity in historical specimens, but there are limitations on the overlaps between DNA results and physical contents, where morphological identification still reigns in taxon counts, but metabarcoding sometimes provides more taxonomic resolution, and can be used to track DNA from other organisms such as fungi beyond the directly surveyed specimens.

Animals↗

PubMed2026

Rhodococcus dendrobeaniae sp. nov., an actinomycete isolated from an Arctic marine invertebrate exhibiting cytotoxic activity, and an emended description of Rhodococcus sovatensis.

A polyphasic study was conducted to establish the taxonomic status of strain T060T, an orange, aerobic, coccoid and non-motile actinomycete, isolated from a marine bryozoan (Dendrobeania sp.) collected in the Barents Sea. Phylogenetic analysis of the 16S rRNA gene sequences revealed Rhodococcus sovatensis DSM 102881T as the closest related species to strain T060T with a similarity of 99.54%. Phylogenomic analysis confirmed a close relationship between T060T and R. sovatensis DSM 102881T, while supporting their distinction. Digital DNA-DNA hybridization and average nucleotide identity values between strain T060T and R. sovatensis DSM 102881T were 26.4 and 84.3%, respectively, supporting the delineation of the isolate as a new species. Genomic characterization of the assembled genomes of T060T and R. sovatensis DSM 102881T showed genome sizes of 5.3 and 4.2 Mbp, with a G + C content of 64.38 and 65.01%, respectively. Genome analysis of strain T060T identified 15 biosynthetic gene clusters (BGCs) with low sequence similarity to known BGCs, indicating its capacity to produce unknown, potentially bioactive secondary metabolites. Furthermore, growth of T060T in eight different media revealed condition-dependent cytotoxic activity. The strongest cytotoxicity was observed for fractionated extracts from T060T grown in half-strength ISP 2 with filtered seawater against the human malignant cell lines MCF7 and A2058, and to a lesser extent against the non-malignant MRC5 cell line, highlighting its biotechnological potential. Based on the data from polyphasic taxonomy studies, it is proposed that strain T060T be classified in the genus Rhodococcus as Rhodococcus dendrobeaniae sp. nov. Additionally, the acquired data of R. sovatensis were used to amend its original description.

Rhodococcus↗

PubMed2026

Signaling mechanisms of vasopressin/oxytocin-type neuropeptide-induced muscle contraction in the sea cucumber Apostichopus japonicus.

The myoregulatory action of vasopressin/oxytocin (VP/OT)-type neuropeptides is evolutionarily conserved across Bilateria. In vertebrates, the signaling cascades involved have been comprehensively characterized in several muscle types, including uterine and gastrointestinal smooth muscles. VP/OT-type neuropeptide-induced muscle contraction or relaxation has been reported in a variety of invertebrates, but the downstream signaling pathways responsible for these effects have yet to be elucidated. Here, using heterologous cell systems and in vitro pharmacological experiments, we investigated the signaling pathways underlying VP/OT-type neuropeptide (holotocin) induced contraction of the longitudinal muscle of the body wall (LMBW) in the sea cucumber Apostichopus japonicus (phylum Echinodermata), a deuterostome invertebrate. Holotocin-induced contraction of the LMBW comprised two distinct phases: an initial rapid phasic contraction followed by a sustained tonic contraction. Pharmacological experiments revealed that upon binding to its receptor AjHOR, holotocin activates a Gαq-dependent pathway, leading to phospholipase C (PLC) activation and subsequent hydrolysis of phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol 1,4,5-trisphosphate (IP3) and diacylglycerol (DAG). IP3 triggers Ca2+ release from intracellular Ca2+ stores via IP₃ receptors (IP3R), but depletion of intracellular Ca2+ does not activate store-operated Ca2+ entry (SOCE). DAG activates protein kinase C (PKC), which may modulate the activity of ion channels in the plasma membrane, resulting in membrane depolarization, opening of voltage-gated Ca2+ channels (VGCCs), and subsequent influx of extracellular Ca2+. Overall, this study reveals similarities and differences in the signaling pathways mediating smooth muscle contraction in invertebrates and vertebrates, providing new insights into the evolution of these mechanisms across the Bilateria.

Ca(2+)↗

PubMed2026

Coating materials enhance urochordate primary cell culture adherence.

Marine invertebrate cell cultures are a potential source for diverse biotechnological applications, given the wide range of bioactive compounds they synthesize and accumulate. Yet, the number of established marine invertebrate cell culture systems remains limited compared with those of insects and vertebrates, particularly with respect to adherent cell cultures. Here we studied the in vitro adherence of circulating blood cells from the colonial ascidian Botryllus schlosseri. Two experimental approaches were employed, seeding blood cells either alone (setup 1) or in combination with tissue fragments (setup 2), using three basal media (DMEM, DMEM/F-12, RPMI) on culture plates coated with either Poly-L/D-lysine, gelatin, collagen, or laminin. Each experiment lasted for up to 3 d. Setup 1 results reveal that Botryllus cells remain viable and can adhere to coated surfaces in all tested media. Collagen- and laminin-coated plates supported longer-term cultures, whereas Poly-D (or L)-lysine coatings were more suitable for short-term studies. Among the basal media, RPMI and DMEM/F12 most effectively supported cell attachment. Setup 2 plates consistently showed higher cell adherence compared to setup 1, suggesting that tissue-derived factors may enhance attachment. Overall, circulating Botryllus cells demonstrate the capacity for substrate adhesion in vitro, offering a foundation for the development of adherent cell cultures.

Animals↗

PubMed2025

Multiomics Reveal Associations Between CpG Methylation, Histone Modifications and Transcription in a Species That has Lost DNMT3, the Colorado Potato Beetle.

Insects display exceptional phenotypic plasticity, which can be mediated by epigenetic modifications, including CpG methylation and histone modifications. In vertebrates, both are interlinked and CpG methylation is associated with gene repression. However, little is known about these regulatory systems in invertebrates, where CpG methylation is mainly restricted to gene bodies of transcriptionally active genes. A widely conserved mechanism involves the co-transcriptional deposition of H3K36 trimethylation and the targeted methylation of unmethylated CpGs by the de novo DNA methyltransferase DNMT3. However, DNMT3 has been lost multiple times in invertebrate lineages raising the question of how the links between CpG methylation, histone modifications and gene expression are affected by its loss. Here, we report the epigenetic landscape of Leptinotarsa decemlineata, a beetle species that has lost DNMT3 but retained CpG methylation. We combine RNA-seq, enzymatic methyl-seq and CUT&Tag to study gene expression, CpG methylation and patterns of H3K36me3 and H3K27ac histone modifications on a genome-wide scale. Despite the loss of DNMT3, H3K36me3 mirrors CpG methylation patterns. Together, they give rise to signature profiles for expressed and not expressed genes. H3K27ac patterns show a prominent peak at the transcription start site that is predictive of expressed genes irrespective of their methylation status. Our study provides new insights into the evolutionary flexibility of epigenetic modification systems that urge caution when generalizing across species.

Animals↗

PubMed2026

Target Capture of Ancient Shell DNA Enables Phylogenetic Reconstruction of Deep-Sea Molluscs.

Target capture is widely used to enrich endogenous DNA from calcium phosphate skeletal material in vertebrates, but its performance on calcium carbonate hard parts widely produced by invertebrates remains poorly understood. Here, we compared DNA recovery from four fresh and 12 ancient (eight radiocarbon-dated to 1671-1135 years old before present) deep-sea vesicomyid clam shells, including species Archivesica marissinica, A. nanshaensis and A. okutanii, using whole-genome sequencing (WGS) or target capture of ultraconserved elements (UCEs). WGS achieved 16.65% on-target read recovery of UCEs from fresh soft tissue, but < 1% from shell specimens. By contrast, UCE capture in the same specimen increased on-target reads by up to 155-fold, reaching 29.84% in fresh shells and up to 72-fold, reaching 19.89% in ancient shells. Target capture of UCEs recovered 142-1001 loci per sample compared to 0-230 with WGS alone. Ancient shells of A. marissinica and A. okutanii, based on reads mapped with bwa-mem2 and bbmap, exhibited characteristic post-mortem DNA damage signals, with average 5'-end C-to-T misincorporation rates of 3.46% and 15.97%, respectively, exceeding the levels observed in fresh A. marissinica shells (maximum 1.24%). UCE-based phylogenetic reconstructions incorporating shell ancient DNA recovered two major clades within Pliocardiinae, consistent with published phylogenomic trees. Together, these findings demonstrate that target-capture enrichment enables effective recovery of highly degraded DNA from ancient mollusc shells and supports robust phylogenetic inference at the intrageneric scale, expanding the utility of shells-one of the most abundant invertebrate remains-for evolutionary, biogeographic and conservation studies.

Animals↗

PubMed2026

Evolutionary conservation and adaptability of cholecystokinin neuropeptide signaling in the sea cucumber Apostichopus japonicus.

BACKGROUND: Food ingestion is fundamental for animal survival and growth, with the cessation of feeding upon nutrient fulfillment being tightly regulated by a variety of satiety factors. Notably, sulfakinin/cholecystokinin (SK/CCK)-type neuropeptide signaling has been identified as an inhibitory regulator of food intake across the animal kingdom. However, its regulatory mechanism in feeding in deuterostome invertebrates remains unclear. Here, we characterized SK/CCK-type signaling in a deuterostome invertebrate, the sea cucumber Apostichopus japonicus (phylum Echinodermata). RESULTS: A single SK/CCK-type precursor in A. japonicus generates two mature peptides (AjSK/CCK1, AjSK/CCK2) that activate a shared receptor (AjSK/CCKR), triggering Ca2+ mobilization via the Gαq-dependent pathway and extracellular signal regulated kinase 1/2 (ERK1/2) phosphorylation. Both peptides induce dose-dependent contraction of longitudinal muscles, while AjSK/CCK2 additionally elicits sustained contraction of the posterior intestine, an effect absent in other gut regions. Long-term injection of both peptides reduces food intake and significantly downregulates orexin-type neuropeptide genes (AjOrexin1P, AjOrexin2P) in the circumoral nerve ring (CNR) and intestine. CONCLUSIONS: Unlike mammals, where CCK inhibits feeding by contracting the pyloric sphincter to delay gastric emptying, SK/CCK-type peptides in sea cucumbers exert their anorexic effect in part by selectively contracting the posterior intestine, thereby inhibiting intestinal emptying. This divergence in action sites highlights the evolutionary adaptability of SK/CCK-type signaling as a conserved inhibitory regulator of feeding across bilaterian animals. Elucidating these mechanisms in the economically important A. japonicus may inform development of appetite-promoting agents for sustainable aquaculture.

Animals↗

PubMed2023

Evolution of Orthonectida body plan.

Orthonectida is an enigmatic group of animals with still uncertain phylogenetic position. Orthonectids parasitize various marine invertebrates. Their life cycle comprises a parasitic plasmodium and free-living males and females. Sexual individuals develop inside the plasmodium; after egress from the host they copulate in the external environment, and the larva, which has developed inside the female infects a new host. In a series of studied orthonectid species simplification of free-living sexual individuals can be clearly traced. The number of longitudinal and transverse muscle fibers is gradually reduced. In the nervous system, simplification is even more pronounced. The number of neurons constituting the ganglion is dramatically reduced from 200 in Rhopalura ophiocomae to 4-6 in Intoshia variabili. The peripheral nervous system undergoes gradual simplification as well. The morphological simplification is accompanied with genome reduction. However, not only genes are lost from the genome, it also undergoes compactization ensured by extreme reduction of intergenic distances, short intron sizes, and elimination of repetitive elements. The main trend in orthonectid evolution is simplification and miniaturization of free-living sexual individuals coupled with reduction and compactization of the genome.

Animals↗

PubMed2026

Reproduction on the Rocks: Life History of a Freshwater Macrobioeroding Bivalve.

Macrobioerosion, the excavation and removal of consolidated mineral substrates by macrofauna, is well established in marine systems, where macrobioeroders drive carbonate cycling, sediment production and habitat formation. In freshwater ecosystems, however, it has been documented in only a small number of invertebrate taxa and remains a poorly resolved ecological process. Among these, the teredinid shipworm Lithoredo abatanica represents a remarkable departure from the wood-boring ecology of its family, having evolved to excavate and ingest limestone in fresh water. Despite this remarkable ecological transition, its reproductive biology and life history remain unknown. Here, we investigate the reproductive mode and life history strategy of this species using population size structure, in situ observations of siphonal morphology, and sperm morphometrics. We show that L. abatanica reaches exceptional dimensions, with measured body lengths exceeding 100 mm, one intact empty burrow exceeding 200 mm and in-water observations indicating burrows possibly exceeding 500 mm, establishing it as the largest known freshwater macrobioeroder. Its large size and dense aggregations indicate considerable capacity for local rock breakdown and habitat modification within the Abatan River system (Bohol, Philippines). Recently settled juveniles (< 10 mm) alongside reproductively mature individuals indicate ongoing recruitment. The morphology of the siphons and calcareous tube appears to preclude direct sperm transfer via pseudocopulation, while sperm morphometrics are consistent with external fertilisation. Together, these findings indicate that L. abatanica reproduces via broadcast spawning with external fertilisation and likely possesses a planktotrophic larval phase. This raises a fundamental question: how does a broadcast-spawning species with planktotrophic larvae maintain populations up to 15 km upstream in a flowing freshwater river subject to persistent downstream advection? By resolving the life history of the largest known freshwater macrobioeroder, this study provides critical insight into the persistence, dispersal and ecological role of a globally unique riverine ecosystem engineer.

broadcast spawning↗

PubMed2026

Fine-Scale Population Genomics Reveals Genetic Differentiation in the Brooding Amphipod Cheirimedon femoratus Across the South Shetland Islands, Antarctica.

Antarctic marine ecosystems are sensitive to environmental change, and impacts on processes such as population connectivity will play a fundamental role in future population dynamics and persistence, affecting short-term demography and long-term evolution. We investigated the population genomics of the common benthic brooding Antarctic amphipod Cheirimedon femoratus (Pfeffer, 1888), using 8837 high-quality single-nucleotide polymorphisms (SNPs) from 87 individuals collected at 4 sites in the South Shetland Islands, separated by up to 200 km: Deception Island, King George Island, Livingston Island, and Snow Island. While Admixture, F ST, principal component analysis (PCA), and demographic (Ne) analyses revealed a generally weak population genetic structure, Livingston Island emerged as a distinct population, especially compared to King George Island. All populations showed a heterozygote deficit with positive inbreeding coefficients (F IS), particularly high in the Snow Island population (~0.55). Tajima's D test suggested overall neutral evolution, although slight variation was observed among sites. Despite the limited dispersal potential of this brooding species, the observed connectivity may be maintained through passive dispersal, likely via floating macroalgae or ice-rafted debris, facilitated by prevailing regional ocean currents. This may enhance the population resilience of Antarctic benthic communities under environmental change, including regional warming and shifts in ocean circulation, compared to more isolated populations. Our findings underscore the complex interplay between passive connectivity and fine-scale differentiation in shaping Antarctic benthic invertebrate diversity.

Amphipoda↗

PubMed2026

Pesticide occurrence, transformation, and transport from wastewater treatment plants into stream networks with diverse land uses.

Neonicotinoid insecticides and strobilurin fungicides are detected in many environmental compartments and have been associated with negative environmental and human health implications. Wastewater treatment plants (WWTPs) are often hotspots for introducing such contaminants into the environment. Therefore, the occurrence of strobilurin fungicides, neonicotinoids, and their metabolites at two WWTPs with varying land uses and population sizes was investigated. Polar organic chemical integrative samplers were deployed in WWTP influent and effluent and placed upstream and downstream of the effluent mixing zone for 2 weeks in April and July 2022. Biosolids were also collected at each time point. Neonicotinoids were detected with the highest frequency (68%), followed by strobilurin fungicides (49%) and neonicotinoid metabolites (31%). Time-weighted average concentrations for influent/effluent ranged from 85.2 ± 87.8 to 409.4 ± 74.5 ng/L. Pesticide concentrations, specifically the metabolites, typically increased from influent to effluent, resulting in effluent having higher pesticide loads than influent. Pesticide concentrations varied between the upstream and downstream monitoring locations by analyte, with WWTP samples in the highly developed region having significantly higher concentrations of pesticides and less variation by monitoring period. Chronic ecotoxicity benchmarks for freshwater invertebrates for imidacloprid were surpassed in treated effluent at both WWTPs in July and in the downstream monitoring location in the heavily developed area. Findings support the need for further exploration of pesticide contributions from WWTPs to river systems, specifically related to metabolite contributions to downstream streams and their effects on aquatic environments.

Water Pollutants, Chemical↗