Oceanic regions shape the composition of the Antarctic plastisphere.

Antarctica, once considered pristine, is increasingly threatened by plastic pollution, with debris found in its waters, sediments, sea ice, and biota. Here, we provide a comprehensive molecular survey of both prokaryotic and eukaryotic diversity on plastics around the Antarctic Peninsula, addressing a gap in existing research. Using eDNA metabarcoding, we identified diverse communities, with Pseudomonadota and Bacteroidota dominating prokaryotic communities, while Gyrista (mostly diatoms), Fungi and Arthropods were prevalent among eukaryotes.

Functional Roles of the Seagrass () Holobiont Change with Plant Development.

Seagrass meadows play a critical role in biogeochemical cycling, especially in nitrogen and sulphur processes, driven by their associated microbiome. This study provides a novel functional analysis of microbial communities in seagrass () rhizosphere and endosphere, comparing seedlings and mature plants. While nitrogen-fixing bacteria are more abundant in seedlings, mature plants exhibit greater microbial diversity and stability.

Is the Composition of Communities in Bromeliad Water and Adjacent Soil Similar?

Soil and bromeliads are important habitats contributing to the biodiversity of the Atlantic Forest in Brazil. However, knowledge of unicellular eukaryotes and bacteria in these environments remains limited. This study compared the diversity and community structure of unicellular eukaryotes, fungi, metazoan, and bacteria in bromeliad water tanks (BWT) and adjacent soil using 16S and 18S rRNA gene metabarcoding.

Maximising environmental pressure-response relationship signals from diatom-based metabarcoding in rivers.

DNA metabarcoding has been performed on a large number of river phytobenthos samples collected from the UK, using rbcL primers optimised for diatoms. Within this dataset the composition of non-diatom sequence reads was studied and the effect of including these in models for evaluating the nutrient gradient was assessed. Whilst many non-diatom taxonomic groups were detected, few contained the full diversity expected in riverine environments.

Plastisphere composition in a subtropical estuary: Influence of season, incubation time and polymer type on plastic biofouling.

Plastics are abundant artificial substrates in aquatic systems that host a wide variety of organisms (the plastisphere), including potential pathogens and invasive species. Plastisphere communities have many complex, but not well-understood ecological interactions. It is pivotal to investigate how these communities are influenced by the natural fluctuations in aquatic ecosystems, especially in transitional environments such as estuaries.

Monitoring of benthic eukaryotic communities in two tropical coastal lagoons through eDNA metabarcoding: a spatial and temporal approximation.

Tropical coastal lagoons are important ecosystems that support high levels of biodiversity and provide several goods and services. Monitoring of benthic biodiversity and detection of harmful or invasive species is crucial, particularly in relation to seasonal and spatial variation of environmental conditions. In this study, eDNA metabarcoding was used in two tropical coastal lagoons, Chacahua (CH) and Corralero (C) (Southern Mexican Pacific), to describe the benthic biodiversity and its spatial-temporal dynamics.

Floating plastics and their associated biota in the Western South Atlantic.

The lack of information about plastic pollution in many marine regions hinders firm actions to manage human activities and mitigate their impacts. This study conducted for the first time a quali-quantitative evaluation of floating plastics and their associated biota from coastal and oceanic waters in South Brazil. Plastics were collected using a manta net, and were categorized according to their shape, size, malleability and polymer composition.

Parasites, pathogens, and other symbionts of copepods.

There is a large diversity of eukaryotic symbionts of copepods, dominated by epizootic protists such as ciliates, and metazoan parasites. Eukaryotic endoparasites, copepod-associated bacteria, and viruses are less well known, partly due to technical limitations. However, new molecular techniques, combined with a range of other approaches, provide a complementary toolkit for understanding the complete symbiome of copepods and how the symbiome relates to their ecological roles, relationships with other biota, and responses to environmental change.

Mechanistic strategies of microbial communities regulating lignocellulose deconstruction in a UK salt marsh.

Background: Salt marshes are major natural repositories of sequestered organic carbon with high burial rates of organic matter, produced by highly productive native flora. Accumulated carbon predominantly exists as lignocellulose which is metabolised by communities of functionally diverse microbes. However, the organisms that orchestrate this process and the enzymatic mechanisms employed that regulate the accumulation, composition and permanence of this carbon stock are not yet known.

Soil fungal networks maintain local dominance of ectomycorrhizal trees.

The mechanisms regulating community composition and local dominance of trees in species-rich forests are poorly resolved, but the importance of interactions with soil microbes is increasingly acknowledged. Here, we show that tree seedlings that interact via root-associated fungal hyphae with soils beneath neighbouring adult trees grow faster and have greater survival than seedlings that are isolated from external fungal mycelia, but these effects are observed for species possessing ectomycorrhizas (ECM) and not arbuscular mycorrhizal (AM) fungi. Moreover, survival of naturally-regenerating AM seedlings over ten years is negatively related to the density of surrounding conspecific plants, while survival of ECM tree seedlings displays positive density dependence over this interval, and AM seedling roots contain greater abundance of pathogenic fungi than roots of ECM seedlings.

Diverse groups of fungi are associated with plastics in the surface waters of the Western South Atlantic and the Antarctic Peninsula.

Marine plastic pollution has a range of negative impacts for biota and the colonization of plastics in the marine environment by microorganisms may have significant ecological impacts. However, data on epiplastic organisms, particularly fungi, is still lacking for many ocean regions. To evaluate plastic associated fungi and their geographic distribution, we characterised plastics sampled from surface waters of the western South Atlantic (WSA) and Antarctic Peninsula (AP), using DNA metabarcoding of three molecular markers (ITS2, 18S rRNA V4 and V9 regions).

Diet in the Driving Seat: Natural Diet-Immunity-Microbiome Interactions in Wild Fish.

Natural interactions between the diet, microbiome, and immunity are largely unstudied. Here we employ wild three-spined sticklebacks as a model, combining field observations with complementary experimental manipulations of diet designed to mimic seasonal variation in the wild. We clearly demonstrate that season-specific diets are a powerful causal driver of major systemic immunophenotypic variation.

Polychaete mucopolysaccharide alters sediment microbial diversity and stimulates ammonia-oxidising functional groups.

Sediment nitrogen cycling is a network of microbially mediated biogeochemical processes that are vital in regulating ecosystem functioning. Mucopolysaccharides (mucus) are produced by many invertebrates and have the potential to be an important source of organic carbon and nitrogen to sediment microorganisms. At present, we have limited understanding of how mucopolysaccharide moderates total sediment microbial communities and specific microbial functional groups that drive nitrogen cycling processes.

Limited congruence exhibited across microbial, meiofaunal and macrofaunal benthic assemblages in a heterogeneous coastal environment.

One of the most common approaches for investigating the ecology of spatially complex environments is to examine a single biotic assemblage present, such as macroinvertebrates. Underlying this approach are assumptions that sampled and unsampled taxa respond similarly to environmental gradients and exhibit congruence across different sites. These assumptions were tested for five benthic groups of various sizes (archaea, bacteria, microbial eukaryotes/protists, meiofauna and macrofauna) in Plymouth Sound, a harbour with many different pollution sources.

Active bacterioplankton community response to dissolved 'free' deoxyribonucleic acid (dDNA) in surface coastal marine waters.

Seawater contains dissolved 'free' DNA (dDNA) that is part of a larger <0.2 µm pool of DNA (D-DNA) including viruses and uncharacterised bound DNA. Previous studies have shown that bacterioplankton readily degrade dDNA, and culture-based approaches have identified several potential dDNA-utilising taxa.

Partitioning of soil phosphorus among arbuscular and ectomycorrhizal trees in tropical and subtropical forests.

Partitioning of soil phosphorus (P) pools has been proposed as a key mechanism maintaining plant diversity, but experimental support is lacking. Here, we provided different chemical forms of P to 15 tree species with contrasting root symbiotic relationships to investigate plant P acquisition in both tropical and subtropical forests. Both ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM) trees responded positively to addition of inorganic P, but strikingly, ECM trees acquired more P from a complex organic form (phytic acid).

Community responses to seawater warming are conserved across diverse biological groupings and taxonomic resolutions.

Temperature variability is a major driver of ecological pattern, with recent changes in average and extreme temperatures having significant impacts on populations, communities and ecosystems. In the marine realm, very few experiments have manipulated temperature , and current understanding of temperature effects on community dynamics is limited. We developed new technology for precise seawater temperature control to examine warming effects on communities of bacteria, microbial eukaryotes (protists) and metazoans.

Coastal bacterioplankton community response to diatom-derived polysaccharide microgels.

Phytoplankton-derived polysaccharide microgels, including transparent exopolymer particles (TEP), are a major component of the marine organic carbon pool. Previous studies have made correlative links between phytoplankton material and bacterioplankton, and performed experiments that assess general responses to phytoplankton, yet there is a lack of direct empirical evidence of specific bacterioplankton responses to natural phytoplankton polysaccharide microgels. In this study, we used diatom produced TEP in controlled incubation experiments to determine the impact of polysaccharide microgels on a coastal bacterioplankton community.

Multi-year assessment of coastal planktonic fungi reveals environmental drivers of diversity and abundance.

Mycoplankton have so far been a neglected component of pelagic marine ecosystems, having been poorly studied relative to other plankton groups. Currently, there is a lack of understanding of how mycoplankton diversity changes through time, and the identity of controlling environmental drivers. Using Fungi-specific high-throughput sequencing and quantitative PCR analysis of plankton DNA samples collected over 6 years from the coastal biodiversity time series site Station L4 situated off Plymouth (UK), we have assessed changes in the temporal variability of mycoplankton diversity and abundance in relation to co-occurring environmental variables.

Polychaete burrows harbour distinct microbial communities in oil-contaminated coastal sediments.

Previous studies have shown that the bioturbating polychaete Hediste (Nereis) diversicolor can affect the composition of bacterial communities in oil-contaminated sediments, but have not considered diversity specifically within bioturbator burrows or the impact on microbial eukaryotes. We tested the hypothesis that H. diversicolor burrows harbour different eukaryotic and bacterial communities compared with un-bioturbated sediment, and that bioturbation stimulates oil degradation.

High-throughput sequencing reveals neustonic and planktonic microbial eukaryote diversity in coastal waters.

Neustonic organisms inhabit the sea surface microlayer (SML) and have important roles in marine ecosystem functioning. Here, we use high-throughput 18S rRNA gene sequencing to characterize protist and fungal diversity in the SML at a coastal time-series station and compare with underlying plankton assemblages. Protist diversity was higher in February (pre-bloom) compared to April (spring bloom), and was lower in the neuston than in the plankton.

Intertidal epilithic bacteria diversity changes along a naturally occurring carbon dioxide and pH gradient.

Intertidal epilithic bacteria communities are important components of coastal ecosystems, yet few studies have assessed their diversity and how it may be affected by changing environmental parameters. Submarine CO2 seeps produce localised areas of CO2-enriched seawater with reduced pH levels. We utilised the seawater pH/CO2 gradient at Levante Bay (Italy) to test the hypothesis that epilithic bacteria communities are modified by exposure to seawater with the varying chemical parameters.

Seasonal microbial community dynamics correlate with phytoplankton-derived polysaccharides in surface coastal waters.

Phytoplankton produce large amounts of polysaccharide gel material known as transparent exopolymer particles (TEP). We investigated the potential links between phytoplankton-derived TEP and microbial community structure in the sea surface microlayer and underlying water at the English Channel time-series station L4 during a spring diatom bloom, and in two adjacent estuaries. Major changes in bacterioneuston and bacterioplankton community structure occurred after the peak of the spring bloom at L4, and coincided with the significant decline of microlayer and water column TEP.

Differences between aerobic and anaerobic degradation of microphytobenthic biofilm-derived organic matter within intertidal sediments.

Within intertidal sediments, much of the dissolved organic carbon (DOC) consists of carbohydrate-rich extracellular polymeric substances (EPS) produced by microphytobenthic biofilms. EPS are an important source of carbon and energy for aerobic and anaerobic microorganisms owing to burial of microphytobenthos and downward transport of their exudates. We established slurries of estuarine biofilms to determine the fate of organic carbon and EPS fractions, differing in size and complexity, under oxic and anoxic conditions.

Evaluation of the MIDTAL microarray chip for monitoring toxic microalgae in the Orkney Islands, U.K.

Harmful or nuisance algal blooms can cause economic damage to fisheries and tourism. Additionally, toxins produced by harmful algae and ingested via contaminated shellfish can be potentially fatal to humans. The seas around the Orkney Islands, UK currently hold a number of toxic algal species which cause shellfishery closures in most years.