ArticleLiterature Review

Substratum‐Associated Microbiota

Authors:
  • Saint Catherine University, St. Paul, MN
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Abstract

Highlights of new, interesting, and emerging research findings on substratum‐associated microbiota covered from a survey of 2019 literature from primarily freshwaters, provide insight into research trends of interest to the Water Environment Federation and others interested in benthic, aquatic environments. Coverage of topics on bottom‐associated or attached algae and cyanobacteria, though not comprehensive, includes new methods, taxa new to science, nutrient dynamics, auto‐ and heterotrophic interactions, grazers, bioassessment, herbicides and other pollutants, metal contaminants, and nuisance, bloom‐forming and harmful algae. Coverage of bacteria, also not comprehensive, focuses on the ecology of benthic biofilms and microbial communities, along with the ecology of microbes like Caulobacter crescentus, Rhodobacter and other freshwater microbial species. Bacterial topics covered also include metagenomics and metatranscriptomics, toxins and pollutants, bacterial pathogens and bacteriophages, and bacterial physiology. Readers may use this literature review to learn about or renew their interest in the recent advances and discoveries regarding substratum‐associated microbiota.

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... Approaches using biological control mechanisms have been an alternative to chemical fungicides, pesticide, and herbicide in plantation management (Köhl et al. 2019;Furey et al. 2020;Wang et al. 2020a, b). Currently, there are studies showing that several microorganisms are capable of inhibiting the growth of pathogenic species to plants (Panth et al. 2020). ...
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Periphyton communities associated with submerged plant detritus contain interacting autotrophic and heterotrophic microbes, and are sites of extracellular enzymatic activity. The strength and nature of these interactions might be expected to change over time as microbial communities develop on plant litter. Microbial interactions and enzymatic activity can be altered by nutrient availability, suggesting that litter stoichiometry could also affect these phenomena. We grew wetland plants under ambient and nutrient‐enriched conditions to generate plant litter of differing nutrient content. In two experiments, we investigated: (1) the influence of algal photosynthesis on fungal and bacterial production and the activities of four extracellular enzymes throughout a 54‐day period of microbial colonisation and growth; and (2) the influence of litter stoichiometry on these relationships. Ambient and nutrient‐enriched standing‐dead plant litter was collected and then submerged in wetland pools to allow for natural microbial colonisation and growth. Litter samples were periodically retrieved and transported to the laboratory for experiments manipulating photosynthesis using the photosystem II inhibitor DCMU (which effectively prevents algal photosynthetic activity). Algal (14C‐bicarbonate), bacterial (3H‐leucine), and fungal (14C‐acetate) production, and β‐glucosidase, β‐xylosidase, leucine aminopeptidase, and phosphatase activities (MUF‐ or AMC‐labelled fluorogenic substrates) were measured under conditions of active and inhibited algal photosynthesis. Photosynthesis stimulated overall fungal and bacterial production in both experiments, although the strength of stimulation varied amongst sampling dates. Phosphatase activity was stimulated by photosynthesis during the first, but not the second, experiment. No other enzymatic responses to short‐term photosynthesis manipulations were observed. Microbial communities on high‐nutrient litter occasionally showed increased extracellular enzyme activity, fungal growth rates, and bacterial production compared to communities on non‐enriched litter, but algal and fungal production were not affected. Litter stoichiometry had no effects on fungal, bacterial, or enzymatic responses to photosynthesis, but the mean enzyme vector analysis angle (a measure of P‐ versus N‐acquiring enzyme activity) was positively correlated to litter N:P, suggesting that elevated litter N:P led to an increase in the relative activity of P‐acquiring enzymes. These results supported the hypothesis that algal photosynthesis strongly influences heterotrophic microbial activity on macrophyte leaf litter, especially that of fungi, throughout microbial community development. However, the strength of this photosynthetic stimulation does not generally depend on small differences in litter nutrient content. Stimulation of microbial heterotrophs by algal photosynthesis could drive diurnal shifts in periphyton community and aquatic ecosystem function, as well as linking green (photoautotroph‐based) and brown (detrital‐based) food webs.
Article
During a survey of freshwater diatoms from streams in the upper reaches of the Liujiang River, Guangxi Province, China, a new Cymbella species, Cymbella liujiangensis sp. nov. was recorded. A detailed morphological description of C. liujiangensis is presented, based on light and scanning electron microscopy. The main features of C. liujiangensis include strongly dorsiventral valves with slightly truncate and obtusely rounded ends and one very large, transaspically-elongated stigma positioned on the ventral side of the central nodule and adjacent to the middle ventral striae. The new species is compared with C. dorsenotata, C. aspera, C. peraspera, C. australica, C. praerupta, C. convexa, C. carssistigmata, C. graciliformis and C. simonsenii, all of which show similarities to Cymbella liujiangensis, but differ in details of size, valve shape, striae density, puncta density, and number of stigmata.
Article
Mass spectrometric methods for the quantitative and qualitative analyses of algal biotoxins are often complicated by co-eluting compounds that present analytically as interferences. This issue is particularly critical for organic polyamines, where co-eluting materials can suppress the formation of cations during electrospray ionization. Here we present an extraction procedure designed specifically to overcome matrix-derived ion suppression of algal toxins in samples of Lyngbya wollei, a filamentous benthic algae known to produce several saxitoxin analogues. Lyngbya wollei samples were collected from a large, persistent harmful algal bloom in Lake Wateree, SC. Six known Lyngbya wollei-specific toxins (LWT1-6) were successfully resolved and quantified against saxitoxin using hydrophilic interaction liquid chromatography coupled with triple quadrupole and quadrupole time-of-flight mass spectrometry. The parent ions [M2+ - H+]+ were observed for LWTs 1-6 and the [M]2+ ion was observed for LWT5. High resolution mass spectra and unique fragmentation ions were obtained for LWTs 1-6. A dilution factor of 50 resulted in a linear calibration of saxitoxin in the algae matrix. Ion suppression was resolved by sample dilution, which led to linear, positive correlations between peak area and mass of the extracted sample (R2 > 0.96). Optimized sample extraction method and instrument parameters are presented.
Article
Algal biomass cultivation has been effectively used as a medium for remediation of nutrients from many was-tewaters. Production systems such as the algal turf scrubber (ATS) that use attached filamentous algae typically show high productivity rates. The biomass productivity performance of the ATS system is influenced by various environmental and process factors, such as water velocity and turbulence, nutrient concentration, and water depth. Although numerous studies have investigated the effect of these factors on the biomass productivity, the effect of substrate complexity has remained relatively unexplored. This study investigates the effect of three dimensional substrate features on algal biomass cultivation. A three-dimensional (3D) design that uses fibers twisted in a flexible strand, attached to a two-dimensional (2D) backing was used as a growth substrate for ATS. Specifically, the role of 3D substrate features (strand spacing and base pile) and their correlating effect on algal biomass productivity were investigated under different nutrient concentrations. Findings from this study suggest that the introduction of vertical structures in three dimensional substrata to support algal attachment and co-lonization has a significant effect on algal biomass productivity, with productivity increasing by as much as 300% with optimum strand spacing. Also, the productivity increase of 3D substrata over 2D substrata was more pronounced under lower nutrient conditions, where a 174% increase in algal biomass yield was observed. The results suggest that vast improvements in biomass productivity are possible in ATS systems by employing 3D substrates, and optimization of substrate design for maximizing productivity is possible through refinement of topographic elements that compose the 3D structure.
Article
In the present study, two new filamentous cyanobacterial strains (NUACC12 and NUACC15) were described based on a comprehensive study of morphological characteristics and molecular analyses. The novel strains were isolated from a shallow freshwater pond in the central region of Thailand. The morphological features of both strains are similar to those of Wollea species, W. ambigua, but are different in the dimensions of heterocyte and akinete cells as well as the absence of a sheath around the trichome. Phylogenetic analyses based on 16S rDNA and 16S–23S rDNA internal transcribed spacer sequences (ITS) revealed that new strains formed a robust supported clade which does not belong to the same clade with the type species of other cyanobacterial genera. Moreover, 16S rDNA sequence similarity between new strains and other putatively related taxa such as Wollea, Amphiheterocytum, Sphaerospermopsis, and Raphidiopsis raciborskii ranged from 96.1–97.4%, a level of similarity low enough for separating species differences. The unique patterns of the ITS secondary structure also clearly support two new strains representing a distinct cyanobacterial species. Considering all the results obtained in the present study, we here name the new genus Neowollea gen. nov., with the type species N. manoromense sp. nov. Based on morphology, ecology, 16S rDNA data and D1–D1′ helix structure, we also propose N. salina comb. nov. (basionym Wollea salina) as an additional species in the novel genus. Furthermore, the results of PCR amplification and GC/MS/MS analysis confirmed that two N. manoromense strains could produce an odorous compound, geosmin.
Article
A new species, Gomphosinica selincuoensis sp. nov., is described from Lake Selincuo, North Tibet, China. This taxon is clearly different from the other species in genus Gomphosinica, with a distinctly protracted, rostrate headpole, relatively higher striae density, and distinctive areolae arrangement within the striae. Striae have areolae mostly in 3 rows, but there are places near the central portion of the valve and at footpole where there are only 2 rows of areolae per stria. Characteristics of this taxon, as observed in light and scanning electron microscopy, support its systematic placement in the genus Gomphosinica. This new species is compared with similar species in Gomphosinica from China and North America, and the biogeographic distribution of the genus is discussed.
Article
A new diatom species, Neidiomorpha dianshaniana sp. nov., found in Dianshan Lake in Shanghai, China, is described herein. The morphology of N. dianshaniana has been documented by light and scanning electron microscopy. Neidiomorpha dianshaniana valves are elliptical in outline with rostrate apices. Raphe is almost straight and filiform. The axial area is narrow and linear. The central area is small, round to transversely elliptical or irregular. Striae are slightly radiate and almost parallel near the apices. Puncta are arranged in undulating longitudinal rows. Neidiomorpha dianshaniana’s most visible feature is its lack of central constriction, in which respect it differs from the three other species in the genus Neidiomorpha.
Article
The effects of salinity (as chloride [Cl] at 600, 1000, 1600, and 2500 mg L⁻¹) and nitrate (as nitrogen [N] loading rates using concentrations of 1, 2, 5, and 10 mg L⁻¹) additions on phytoplankton communities (as chlorophyll and carotenoid pigments) were determined using a fully factorial 3 m³ mesocosm pond experiment. Redundancy analysis followed by variance partitioning analysis (VPA) statistically compared phytoplankton with water chemistry, zooplankton, phytobenthos (aquatic plants and periphyton), and zoobenthos to understand relationships among benthic and pelagic components. Repeated measures analysis of variance (RM-ANOVA) indicated no interactive effects of the 2 treatments. In VPA, physicochemical variables explained the most variance (33.6%) in the phytoplankton pigment dataset relative to benthic primary producers (0.4%) and invertebrates (2.3%). Salinisation led to an increase in biomass of planktonic siliceous algae (Cl ≥1600 mg L⁻¹) and chlorophytes and cyanobacteria (Cl ≥2500 mg L⁻¹), which we infer was caused by increased phosphorus release from sediments while aquatic plants and periphyton declined. Nitrate additions increased the biomass of cryptophytes and chlorophytes at intermediate N loading rates using concentrations of 5 mg L⁻¹ (associated with greater ammonium [NH4-N] availability and shifts in aquatic plant composition). These findings support the hypothesis that the relative availability of reduced versus oxidised N forms is an important driver of phytoplankton composition. Together, these results suggest that pelagic biota are highly sensitive to salinity and nitrate increases, and that the phytoplankton compositional shifts are driven by indirect effects on water chemistry (bioavailable P mobilisation, changes in N forms), which are mediated by benthic processes.
Article
The term “ecosystem engineering” emerged in the 1990s and is commonly used to refer to the activities of larger organisms like beavers and trees in rivers and streams. The focus on larger organisms may be motivated by their more visible effects on the environment. However, while it may be intuitive to suggest that the bigger the organism the bigger its potential engineering effects, there may be microscale organisms who through their number rather than their size can act simultaneously to result in significant impacts. This paper considers biofilms as a candidate ecosystem engineer. It is well known that biofilms play an important role in enriching the sediment matrix of nutrients and in stabilizing sediments. Biofilms may be critical in increasing the habitability of the benthic substratum. In this paper, we consider their potential role in the ontogeny of ecosystems in recently deglaciated terrain. We show how by changing sediment stoichiometry, decreasing sediment erodibility, and reducing surface sediment permeability they may promote primary succession on lateral, incised terraces, which are less perturbed compared with the main active floodplain. This article is categorized under: • Water and Life > Nature of Freshwater Ecosystems • Science of Water > Water and Environmental Change
Article
A freshwater dwelling, tapering, heterocytous cyanobacterium (strain V13) was isolated from an oligotrophic pond in the Shrirampur taluka, Ahmednagar district of Maharashtra in India. Initial morphological examination indicated, that strain V13 belonged to the genus Calothrix. Subsequent molecular and phylogenetic assessment based on 16S rRNA gene, led us to describe the freshwater/terrestrial clade of Calothrix strains without terminal hairs as a new genus Dulcicalothrix gen. nov., with the type species Dulcicalothrix necridiiformans sp. nov. (Strain V13) on the basis of the necridia forming ability of the strain. Also, the 16S-23S ITS secondary structure analysis clearly differentiated strain V13 from the other members of the clade. Past studies and the current state of knowledge makes it imperative to separate the groups Calothrix (marine/freshwater Calothrix), Macrochaete and Dulcicalothrix (freshwater/terrestrial Calothrix) into separate genera in accordance with the International Code of Nomenclature for Algae, Fungi and Plants. Robust phylogenetic evidence and previous reports strongly support the re-erection of the family Calotrichaceae distinct from the existing family Rivulariaceae.
Article
Microcystins produced by several toxic cyanobacterial strains constitute an important problem for public health. Bacterial degradation of these hepatotoxins may play an important role in natural ecosystems, however the nature of the process is very poorly understood. The aim of our study was to investigate the possible interactions between cyanotoxin producers and degraders. Samples collected from twenty four water bodies in western Poland were analysed to determine the chemo-physical parameters, phytoplankton content, bacterial community structure and microcystin-biodegradation potency. A redundancy analysis identified a positive correlation between the capacity of a community to degrade MC-LR and temperature, pH, chlorophyll a concentration and the abundance of MC-producers. A relative abundance of classes F38, TM7-3 and the order WCHB1-81c (Actinobacteria) was significantly higher in the lakes with MC-biodegradation potency. Some specific bacteria genera belonging to Acidobacteria, Chloroflexi, Gemmatimonadetes, Firmicutes and TM7 were closely correlated with the occurrence of Microcystis spp. Furthermore, the MC biodegradation process was connected with the same bacterial groups. Thus, our approach allowed to provide a broader picture of some specific relations between microcystin producers and potential microcystin degraders. A more comprehensive analysis of the existing correlations may be helpful in the understanding of natural mechanisms of MC elimination using bacteria such as MC-degraders.
Article
Fecal microorganisms can enter water bodies in diverse ways, including runoff, sewage discharge, and direct fecal deposition. Once in water, the microorganisms experience conditions that are very different from intestinal habitats. The transition from host to aquatic environment may lead to rapid inactivation, some degree of persistence, or growth. Microorganisms may remain planktonic, be deposited in sediment, wash up on beaches, or attach to aquatic vegetation. Each of these habitats offers a panoply of different stressors or advantages, including UV light exposure, temperature fluctuations, salinity, nutrient availability, and biotic interactions with the indigenous microbiota (e.g., predation and/or competition). The host sources of fecal microorganisms are likewise numerous, including wildlife, pets, livestock, and humans. Most of these microorganisms are unlikely to affect human health, but certain taxa can cause waterborne disease. Others signal increased probability of pathogen presence, e.g., the fecal indicator bacteria Escherichia coli and enterococci and bacteriophages, or act as fecal source identifiers (microbial source tracking markers). The effects of environmental factors on decay are frequently inconsistent across microbial species, fecal sources, and measurement strategies (e.g., culture versus molecular). Therefore, broad generalizations about the fate of fecal microorganisms in aquatic environments are problematic, compromising efforts to predict microbial decay and health risk from contamination events. This review summarizes the recent literature on decay of fecal microorganisms in aquatic environments, recognizes defensible generalizations, and identifies knowledge gaps that may provide particularly fruitful avenues for obtaining a better understanding of the fates of these organisms in aquatic environments.
Article
Five taxa in the genus Neidium, N. iridis, N. beatyi sp. nov., N. vandusenense sp. nov., N. collare sp. nov. and N. lavoieanum sp. nov. are documented from a pond and stream system in the VanDusen Botanical Garden, Vancouver, Canada. Neidium beatyi is a large linear species with multiple longitudinal canals and sagittate apices. The areolae are occluded by finger-like silica extensions on the external surface. This taxon is distinguished from Neidium iridis by the number of longitudinal canals (>5), shape of the valve apices, and smaller size. Neidium vandusenense is broadly linear with distinct rostrate apices. Two-three longitudinal canals are present along each margin. Plastid rbcL sequence data associates this taxon with N. amphigomphus. Neidium collare is an elliptic lanceolate taxon with one longitudinal canal. This taxon is genetically related to N. bisculatum sensu lato, but with a different shape form. Neidium lavoieanum has a valve shape form similar to Neidium potapovae, but is larger and genetically similar to N. productum sensu lato. The five Neidium taxa were observed in a small stream next to Lake Victoria (pond) in the VanDusen Botanical Garden Vancouver, Canada. The water was mildly alkaline with a pH of 7.86, a conductance of 163 µS/cm, higher nutrient loads and low metal content.
Article
Phototrophic biofilms are distributed widely at the sediment/soil-water interfaces (SWI) in paddy fields, where they immobilize phosphorus, thereby reducing its runoff loss. However, how soil carbon, nutrient availability and nutrient ratios drive the phototrophic biofilm community and its contribution to phosphorus cycling is largely unknown. A large scale field investigation in Chinese paddy fields reported here shows that soil organic carbon (SOC) and soil total nitrogen (STN) contents rather than soil total phosphorus (STP) triggered phosphorus immobilization of paddy biofilms, as they changed algal diversity and EPS production. High C: P and N: P ratios favored phosphorus immobilization in biofilm biomass via increasing the abundance of green algae. The C: N ratio on the other hand had only a weak effect on phosphorus immobilization, being counteracted by SOC or STN. Results from this study reveal how the in-situ interception of phosphorus in paddy fields is driven by soil carbon, nutrient availability and nutrient ratios and provide practical information on how to reduce runoff losses of phosphorus by regulating SOC and STN contents.
Article
Widespread use of nanoparticles for different applications has diffused their presence in the environment, particularly in water. Many studies have been conducted to evaluate their effects on aquatic organisms. Microalgae are at the base of aquatic trophic chains. These organisms which can be benthic or pelagic, meaning that they can enter into interaction with all kinds of particulate materials whatever their density, and constitute an interesting model study. The purpose of this review was to gather more than sixty studies on microalgae exposure to the different nanoparticles that may be present in the aquatic environment. After a brief description of each type of nanoparticle (metals, silica and plastic) commonly used in ecotoxicological studies, techniques to monitor their properties are presented. Then, different effects on microalgae resulting from interaction with nanoparticles are described as well as the parameters and techniques for monitoring them. The impacts described in the literature are primarily shading, ions release, oxidative stress, adsorption, absorption and disruption of microalgae barriers. Several parameters are proposed to monitor effects such as growth, photosynthesis, membrane integrity, biochemical composition variations and gene expression changes. Finally, in the literature, while different impacts of nanoparticles on microalgae have been described, there is no consensus on evidence of nanomaterial toxicity with regard to microalgae. A parallel comparison of different nanoparticle types appears essential in order to prioritize which factors exert the most influence on toxicity in microalgae cultures: size, nature, surface chemistry, concentration or interaction time.
Article
This survey of 2018 literature on substratum-associated microbiota presents brief highlights on research findings from primarily freshwaters, but includes those from a variety of aquatic ecosystems. Coverage of topics associated with benthic algae and cyanobacteria, though not comprehensive, includes new methods, taxa new to science, nutrient dynamics, trophic interactions, herbicides and other pollutants, metal contaminants, nuisance, bloom-forming and harmful algae, bioassessment, and bioremediation. Coverage of bacteria, also not comprehensive, focused on methylation of mercury, metal contamination, toxins, and other environmental pollutants, including oil, as well as the use of benthic bacteria as bioindicators, in bioassessment tools and in biomonitoring. Additionally, we cover trends in recent and emerging topics on substratum-associated microbiota of relevance to the Water Environment Federation. PRACTITIONER POINTS: This review of literature from 2018 on substratum-associated microbiota presents highlights of findings on algae, cyanobacteria, and bacteria from primarily freshwaters. Topics covered that focus on algae and cyanobacteria include findings on new methods, taxa new to science, nutrient dynamics, trophic interactions, herbicides and other pollutants, metal contaminants, nuisance, bloomforming and harmful algae, bioassessment, and bioremediation. Topics covered that focus on bacteria include findings on methylation of mercury, metal contamination, toxins and other environmental pollutants, including oil, as well as the us e of benthic bacteria as bioindicators, in bioassessment tools and in biomonitoring. A brief presentation of new, noteworthy and emerging topics on substratum-associated microbiota, build on those from 2017, to highlight those of particular relevance to the Water Environment Federation.
Article
The diatom Didymosphenia geminata (D. geminata) is an invasive periphytic species from the Northern Hemisphere. D. geminata occurrence and mat formation in Patagonia Argentina dates from 2010, spreading throughout Patagonia (provinces of Chubut, Neuquén, Río Negro and Santa Cruz) by 2017. In 2012, the Surveillance and Monitoring Program was implemented by Neuquén government entities. Within this Program 9 sampling campaigns have been conducted at91 sites including streams, rivers, lakes, reservoirs and a canal. Presence or absence of D. geminata cells, abundance of D. geminata and other algal species cells as well as environmental variables were determined in samples. Multivariate Analysis and Generalized Linear Models were used to determine environmental constraints on habitat suitability and requirements for D. geminata. During 2012‐2017, D. geminata cells were detected at 33 out of 91sites sampled. D. geminata was present in lower streams order,with low values of total and dissolved nutrients, conductivity, alkalinity, ions and solutes, and high values of dissolved oxygen (DO) and habitat quality, for the ranges of environmental variables measured at sampling sites. D. geminata abundance was negatively related to stream order. Our results prove that D. geminata is expanding its ecological spectrum, showing a wider tolerance to environmental conditions particularly for phosphorus and nitrogen, some ions such as magnesium, and even temperature; and they confirm some authors’ hypothesis about the ecological behavior of this invasive species. Range expansion and environmental preferences of D. geminata could modify the state of susceptibility to invasion in numerous waterbodies.
Article
A new species of freshwater red alga, Sheathia matouensis, is described and illustrated based on material collected in spring water from the Hongdong region of Shanxi province, China. Phylogenetic analysis of sequence data from the rbcL and psbA indicated the separation between S. matouensis and the other species of genus Sheathia. Additionally, from a morphological point of view, S. matouensis differs from other species of the genus Sheathia by the smaller whorls and carpogonium. Therefore, the results based on both morphological observation and molecular evidences facilitated the proposal of this new species - S. matouensis. It represents another species in the freshwater red algal diversity in China and the description of this new species provides more molecular data for phylogenetic analysis of genus Sheathia.
Article
We present light and scanning electron microscopical observations on one new species of Neidiomorpha from Vietnam. The new species, Nediomorpha gusevii Glushchenko, Kulikovskiy & Kociolek sp. nov., is described on the basis valve outline, shape of the apices, as well as striae and areolae densities. Morphology of Neidiomorpha species, especially on the basis valve outline, is discussed. Neidiomorpha gusevii sp. nov. possesses all of the typical morphological features for the genus, including valves that have longitudinal canals with pleuriseriate coverings, constrictions about the center, rostrate apices, uniseriate striae, absence of renilimbii, straight raphe with small central pores and hooked distal raphe ends going to mantle, and lacking lacinia. Our new species is compared with other three known species from the genus Neidiomorpha, including N. binodis, N. binodiforme and N. sichuaniana. N. gusevii sp. nov. is the first species of Neidiomorpha documented with LM and SEM from Southeast Asia.
Article
Biofilms, composed of periphyton, bacteria and organic detritus, are the base of the food web in many streams and rivers. This media adsorbs and actively sequesters organic and inorganic contaminants from the water column. Here, we demonstrate the utility of using the contaminant concentrations in the biofilm matrix as an environmental media in source tracking and understanding biological impacts at higher trophic levels. Physical partitioning of polychlorinated biphenyl (PCB) and polybrominated diphenyl ether (PBDE) congeners is the dominant mode of uptake from water to biofilm and bioaccumulation factor (BAF) - log Kow relationships suggest that PCB uptake is often near equilibrium between log Kow 5-7. We show that the concentrations of metals in biofilms are more effective at delineating and recording spatial and temporal differences in metals inputs than bed sediments and water samples. The burden of metals in the biofilm matrix explained adverse impacts and variability in periphyton metrics and ecological integrity in macroinvertebrates. This work provides new insights into the partitioning of organic chemicals onto biofilms and shows clear linkages between metals in the biofilm matrix and ecological health of invertebrates that depend on biofilms as a food source.
Article
Environmental microbes frequently live in multispecies biofilms where mutualistic relationships and co-evolution may occur, defining spatial organization for member species and overall community functions. In this context, intrinsic properties emerging from microbial interactions, such as efficient organization optimizing growth and activities in multispecies biofilms, may become the object of fitness selection. However, little is known on the nature of underlying interspecies interactions during establishment of a predictable spatial organization within multispecies biofilms. We present a comparative metatranscriptomic analysis of bacterial strains residing in triple-species and four-species biofilms, aiming at deciphering molecular mechanisms underpinning bacterial interactions responsible of the remarkably enhanced biomass production and associated typical spatial organization they display. Metatranscriptomic profiles concurred with changes in micro-site occupation in response to the addition/removal of a single species, being driven by both cooperation, competition, and facilitation processes. We conclude that the enhanced biomass production of the four-species biofilm is an intrinsic community property emerging from finely tuned space optimization achieved through concerted antagonistic and mutualistic interactions, where each species occupies a defined micro-site favoring its own growth. Our results further illustrate how molecular mechanisms can be better interpreted when supported by visual imaging of actual microscopic spatial organization, and we propose phenotypic adaptation selected by social interactions as molecular mechanisms stabilizing microbial communities.
Article
Freshwater red algae are important components of the algal flora in streams and rivers with high water quality. The order Batrachospermales is the most species-rich portion of the red algal taxa reported throughout North America. We investigated 30 stream segments in South Carolina for the presence of freshwater red algae classified within the Batrachospermales. We collected a total of 50 specimens representing 7 genera and 9 species. We documented Batrachospermum gelatinosum, B. turfosum, Kumanoa skujana, Montagnia australis, Sheathia americana, S. heterocortica, Sirodotia suecica, Tuomeya americana, and Virescentia viride-americana. We observed M. australis and T. americana from the greatest number of streams and in multiple years from the same site. We observed V. viride-americana in 3 streams; our specimens represent the only new record for the state. We generated DNA sequence data of the rbcL gene or gleaned it from the literature for 8 of the 9 taxa identified in the study and confirmed their morphological identification. We collected stream temperature, pH, and conductivity data from sites where we collected 6 of the taxa (Batrachospermum gelatinosum, B. turfosum, M. australis, Sheathia americana, T. americana, and V. viride-americana). Our records were within previously reported ranges for these taxa, although water temperatures tended to be higher than those in previous reports. Present data for the diversity of Batrachospermales in South Carolina represent 64% of the generic/infrageneric and 20% of the species diversity known for North America. This diversity may still be an underestimation of what might be detected by future studies that target more specialized habitats; taxa that are known from neighboring states but not yet reported from South Carolina might be discovered.
Article
The rare desmid species Sphaerozosma luetzelburgianum Krieger and Phymatodocis simplex Förster, endemic to Brazil, are transferred to the genus Spondylosium. Distribution data as well as taxonomic notes on the two species are provided.
Article
We report a new taxonomic entity of Nitella megacephala sp. nov. (Charales, Charophyceae) from Korea. The characean algae collected from two sites (Haenam-gun and Kangjin-gun) had distinctive morphological characteristics representing a new Nitella species. Those samples showed a light-green color in gross morphology and a plant body length up to 13 cm. Moreover, the two-celled dactyls and head formation differed clearly from closely related Nitella species (N. moriokae, N. spiciformis, and N. translucens). From a molecular phylogenetic analysis of rbcL DNA sequences, Nitella megacephala sp. nov formed a single clade with N. translucens, N. moriokae and N. spiciformis, and was distantly related to those three species as a sister taxon. In the terms of interspecific sequence variation, Nitella megacephala showed 3.2–5.5% pairwise distance values with sister groups in phylogenetic tree (N. translucens, N. moriokae and N. spiciformis) and 3.2–9.1% with other of Nitella species. In contrast, its sister group species differed 0.3–1.7% at the interspecific level. These unique morphological and molecular taxonomic characteristics clearly support the establishment of this taxonomic entity as a new species in the genus Nitella (Nitella megacephala sp. nov.)
Article
The genus Coelastrella was established in 1922 by Chodat, and was characterized by being unicellular or in few‐celled aggregations with many longitudinal ribs on cell wall. Many species of this genus showed strong ability to accumulate carotenoids and oils, so they have recently attracted many attentions from researchers due to its potential applicability in the energy and food industries. In this study, a total of 23 strains of Coelastrella were sampled from China, and 3 new species, 2 new varieties were described: C. thermophila sp. nov., C. yingshanensis sp. nov., C. tenuitheca sp. nov., C. thermophila var. globulina var. nov., C. rubescens var. oocystiformis var. nov. Besides 18S rDNA and ITS2 sequences, we have newly sequenced the tufA gene marker for this taxon. Phylogenetic analysis combined with morphological studies revealed 4 morphotypes within the Coelastrella sensu lato clade, which contained the morphotype of original Coelastrella, original Scotiellopsis, Asterarcys, and morphotype of C. vacuolata and C. tenuitheca sp. nov.. The relationships between morphological differences and phylogenic diversity based on different markers were discussed. Our results support that 18S rDNA was too conserved to be used a species‐specific or even a genus‐specific marker in this clade. The topology of tufA gene‐based phylogenetic tree had a better match with the morphological findings.
Article
Olive mill wastewaters (OMW) discharging in river ecosystems cause significant adverse effects on their water chemistry and biological communities. We here examined the effects of OMW loads in four streams of a Mediterranean basin characterized by changing flow. The diatom and macroinvertebrate community structures were compared between upstream (control) and downstream (impacted) sites receiving OMW discharge. We also tested if effects occurred at the organism level, i.e. the occurrence of deformities in diatom valves, and the sediment toxicity on the midge Chironomus riparius. We evaluated these effects through a two-year analysis, at various levels of chemical pollution and dilution capacity. The impacted sites had high phenol concentrations and organic carbon loads during and after olive mill (OM) operation, and were characterized by higher abundances of pollution-tolerant diatom and macroinvertebrate taxa. Diatom valve deformities occurred more frequently at the impacted sites. The development of C. riparius was affected by phenolic compounds and organic carbon concentrations in the sediments. The similarity in the diatom and macroinvertebrate assemblages between control and impacted sites decreased at lower flows. Diatoms were more sensitive in detecting deterioration in the biological status of OMW receiving waterways than macroinvertebrates. Our results indicate that the negative effects of OMW extended to the whole benthic community, at both assemblage and organism level.