Small Metazoans Research Articles

Effect of Simulated Eutrophication of Peatlands on the Microbiome of Utricularia vulgaris L.

Global climate change and increasing human impact are the main factors intensifying eutrophication of peatland ecosystems. Due to the high sensitivity of certain groups of microorganisms, they can serve as indicators of the degree of eutrophication and thereby provide much important information for assessment of the state of peatland ecosystems. However, there is still little knowledge of how changes in the fertility of the environment can affect the microbiome of carnivorous plants in these ecosystems. This study was conducted to verify the following hypotheses: (1) the microbiome of carnivorous plant traps reflects the trophic status of the habitat; (2) an increase in the concentration of biogenic compounds causes a greater increase in the size of microbial communities in the aquatic environment than in the traps. An experiment was carried out in laboratory conditions to determine the effect of simulated eutrophication on the microbiome of Utricularia vulgaris L. An experimental increase in habitat fertility caused an increase in the abundance of bacteria, flagellates, testate amoebae, ciliates, and rotifers, while a decrease in abundance was observed for crustaceans. The increase in the concentration of biogenic compounds also modified the taxonomic composition of communities of microorganisms and small metazoa as well as the strength of trophic relationships; as the trophic level increased, the relationships between bacteria and heterotrophic flagellates; bacteria and testate amoebae; and bacteria and ciliates became stronger.

Bioaccumulation and biomagnification of heavy metals in marine micro-predators

Nematodes represent >3/5 of the abundance of the world’s metazoans and usually account for nearly 90% of the total benthic fauna, playing a key ecological role in the benthic ecosystem functioning on a global scale. These small metazoans include a relevant number of microscopic predators and, in turn, are the most abundant preys of macro-megafauna and fish juveniles thus playing a key role in marine food webs. Here, using two independent approaches, we test the bioaccumulation in marine nematodes of several heavy metals present in contaminated sediments. We report here that nematodes, despite their short life cycle and small size, bioaccumulate significantly heavy metals. Bioaccumulation increases from deposit feeders and microalgal grazers to predators of microbes and other tiny metazoans. These results suggest that nematodes also contribute to their biomagnification along the food webs and can contribute to increase the transfer of contaminants from the sediments to larger organisms.

Biogeographic patterns of micro-eukaryotic generalists and specialists and their effects on regional α-diversity at inter-oceanic scale

Inter-oceanic scale studies allow us to understand the global spread of micro-organisms in marine ecosystems. In this study, micro-eukaryotic communities in marine surface sediment were collected from tropical to Arctic sites. We found that micro-eukaryotic generalists had much higher intraspecific variation than specialists which allow them to distribute more widely through higher spatiotemporal asynchrony and complementary niche preferences among conspecific taxa. Moreover, comparing to the host-associated protozoa and small metazoa, the algae and free-living protozoa with higher intraspecific variation allow them to have wider distribution ranges. Species abundance also played an important role in driving the distribution ranges of generalists and specialists. The generalists had important effects on regional α-diversity even at an inter-oceanic scale which led to the micro-eukaryotic species richness in polar sites to be mainly influenced by the regional generalists but not the local specialists. In particular, more than 97% of algal species in polar sites were shared with the tropical and subtropical sites (including toxic dinoflagellate). Overall, our study suggests that the effects of global change and human activities on the vulnerable high latitude habitats may lead to biotic homogenization for the whole microbial community (not only the dispersal of some harmful algae) through the potential long-distance spread of generalists.

Machine learning algorithms accurately identify free-living marine nematode species.

Identifying species, particularly small metazoans, remains a daunting challenge and the phylum Nematoda is no exception. Typically, nematode species are differentiated based on morphometry and the presence or absence of certain characters. However, recent advances in artificial intelligence, particularly machine learning (ML) algorithms, offer promising solutions for automating species identification, mostly in taxonomically complex groups. By training ML models with extensive datasets of accurately identified specimens, the models can learn to recognize patterns in nematodes' morphological and morphometric features. This enables them to make precise identifications of newly encountered individuals. Implementing ML algorithms can improve the speed and accuracy of species identification and allow researchers to efficiently process vast amounts of data. Furthermore, it empowers non-taxonomists to make reliable identifications. The objective of this study is to evaluate the performance of ML algorithms in identifying species of free-living marine nematodes, focusing on two well-known genera: Acantholaimus Allgén, 1933 and Sabatieria Rouville, 1903. A total of 40 species of Acantholaimus and 60 species of Sabatieria were considered. The measurements and identifications were obtained from the original publications of species for both genera, this compilation included information regarding the presence or absence of specific characters, as well as morphometric data. To assess the performance of the species identification four ML algorithms were employed: Random Forest (RF), Stochastic Gradient Boosting (SGBoost), Support Vector Machine (SVM) with both linear and radial kernels, and K-nearest neighbor (KNN) algorithms. For both genera, the random forest (RF) algorithm demonstrated the highest accuracy in correctly classifying specimens into their respective species, achieving an accuracy rate of 93% for Acantholaimus and 100% for Sabatieria, only a single individual from Acantholaimus of the test data was misclassified. These results highlight the overall effectiveness of ML algorithms in species identification. Moreover, it demonstrates that the identification of marine nematodes can be automated, optimizing biodiversity and ecological studies, as well as turning species identification more accessible, efficient, and scalable. Ultimately it will contribute to our understanding and conservation of biodiversity.

Studying the Metazoan Zooplankton Community Characteristics and Evaluating the Water Quality Based on the Ecological and Functional Zones in Gaoyou Lake

To study the metazoan zooplankton community structure and water quality, we investigated the amount of metazoan zooplankton and the water quality in Gaoyou Lake from January to December 2022. Furthermore, we also evaluated the multi-index and nutritional status of Gaoyou Lake using the comprehensive nutritional status index of water quality, dominant population composition of the metazoan zooplankton, B/T index, and Shannon–Weaver diversity index based on the situation of each ecological and functional zone. The results indicated that the metazoan zooplankton of Gaoyou Lake included 21 families, 31 genera, and 63 species. The rotifers had 8 families, 16 genera, and 34 species, accounting for 53.9% of all species. The cladocerans had 6 families, 7 genera, and 16 species, which accounted for 25.4% of all species. The copepods had 7 families, 8 genera, and 13 species, that accounted for 20.7% of all species. The density and species of small metazoan zooplankton (rotifers) had a higher proportion than large metazoan zooplankton (crustaceans). The average annual metazoan zooplankton density was 1595.7 ind./L, the average annual biomass was 4.31 mg/L, the average annual total nitrogen (TN) was 1.101 mg/L, and the average annual total phosphorus (TP) was 0.082 mg/L. The TN and TP of the Gaoyou Lake were over the standard. The comprehensive nutritional status indices of the water quality in the entire lake and the ecological and functional areas were consistent with the metazoan zooplankton evaluation results, which determined that Gaoyou Lake showed mild eutrophication.

Inverted base composition skews and discontinuous mitochondrial genome architecture evolution in the Enoplea (Nematoda)

BackgroundWithin the class Enoplea, the earliest-branching lineages in the phylum Nematoda, the relatively highly conserved ancestral mitochondrial architecture of Trichinellida is in stark contrast to the rapidly evolving architecture of Dorylaimida and Mermithida. To better understand the evolution of mitogenomic architecture in this lineage, we sequenced the mitogenome of a fish parasite Pseudocapillaria tomentosa (Trichinellida: Capillariidae) and compared it to all available enoplean mitogenomes.ResultsP. tomentosa exhibited highly reduced noncoding regions (the largest was 98 bp), and a unique base composition among the Enoplea. We attributed the latter to the inverted GC skew (0.08) in comparison to the ancestral skew in Trichinellidae (-0.43 to -0.37). Capillariidae, Trichuridae and Longidoridae (Dorylaimida) generally exhibited low negative or low positive skews (-0.1 to 0.1), whereas Mermithidae exhibited fully inverted low skews (0 to 0.05). This is indicative of inversions in the strand replication order or otherwise disrupted replication mechanism in the lineages with reduced/inverted skews. Among the Trichinellida, Trichinellidae and Trichuridae have almost perfectly conserved architecture, whereas Capillariidae exhibit multiple rearrangements of tRNA genes. In contrast, Mermithidae (Mermithida) and Longidoridae (Dorylaimida) exhibit almost no similarity to the ancestral architecture.ConclusionsLongidoridae exhibited more rearranged mitogenomic architecture than the hypervariable Mermithidae. Similar to the Chromadorea, the evolution of mitochondrial architecture in enoplean nematodes exhibits a strong discontinuity: lineages possessing a mostly conserved architecture over tens of millions of years are interspersed with lineages exhibiting architectural hypervariability. As Longidoridae also have some of the smallest metazoan mitochondrial genomes, they contradict the prediction that compact mitogenomes should be structurally stable. Lineages exhibiting inverted skews appear to represent the intermediate phase between the Trichinellidae (ancestral) and fully derived skews in Chromadorean mitogenomes (GC skews = 0.18 to 0.64). Multiple lines of evidence (CAT-GTR analysis in our study, a majority of previous mitogenomic results, and skew disruption scenarios) support the Dorylaimia split into two sister-clades: Dorylaimida + Mermithida and Trichinellida. However, skew inversions produce strong base composition biases, which can hamper phylogenetic and other evolutionary studies, so enoplean mitogenomes have to be used with utmost care in evolutionary studies.

Application of Integrated Fixed-Film Activated Sludge in a Conventional Wastewater Treatment Plant.

It is often only at the operation stage of a wastewater treatment plant that there is a need to adjust the treatment process in terms of variable hydraulic capacity, increased pollutant load, high/low concentration of suspended biomass, or the unfavorable phenomenon of reduced sedimentation capacity of the activated sludge. One of the ways to improve the treatment process efficiency is to increase the biologically active surface by using bio-carriers in the form of fibers, materials, or bio-balls. This paper presents the results of a wastewater treatment plant operation during the period of six months after the implementation of the integrated fixed-film activated sludge (IFAS) technology. The research showed that microorganisms developed both in the activated sludge and on the fibers, positively influencing the activated sludge condition. During the start-up of the IFAS process, ciliates predominated over the other species. However, as oxygen content was high (2 mg/dm3 and more) and textile beds were used, the protozoan population developed intensively, and small metazoans became increasingly common. Throughout the research period, nitrifying and phosphorus-accumulating bacteria were observed both in the activated sludge and on the fibers. Between the 59th and 184th day of operation, numerous microorganisms were detected on the fibers and in the activated sludge, testifying to low biological oxygen demand, good aerobic conditions for nitrification, and long sludge age. However, the process seemed to break down after day 72, when the occurrence of metazoan led to reduced sludge production; after day 88, chemical oxygen demand and total suspended solids in the outflow increased, and oligochaetes and rotifers dominated the suspended sludge and fibers. Results also showed that the textile bed and low ammonia concentration became an excellent substrate for the development of Stentor sp. With regard to chemical and biological oxygen demand, total nitrogen- and total phosphorus-effluent concentrations were mostly within the legally permissible limits throughout the 184 days of operation.

The effect of experimentally simulated climate warming on the microbiome of carnivorous plants – A microcosm experiment

Climate change models predict a potential increase in air temperature ranging from 2 °C to 4 °C. Global warming will therefore significantly influence the functioning of various organisms and ecosystems. However, the effect of the temperature increase on the functioning of the microbiome of carnivorous plants is as yet unknown. The aim of the study was to assess the effect of experimentally simulated climate warming on the microbiome of the traps of Utricularia vulgaris L. - plant included on the red list in the NT (near-threatened) category. We used ‘microcosm’ experiments (a control treatment and treatments with temperature increases of +2 and +4 °C) to determine the reaction of the microbiome of Utricularia traps and the microbes present in the water inhabited by Utricularia to simulated temperature changes in the temperate climate zone. The temperature increase caused an increase in the species richness of ciliates and in the abundance of bacteria, flagellates, and ciliates. On the other hand, there was a decrease in the abundance of testate amoebae, rotifers, and nematodes, i.e. top predators, in both the traps and the peatbog water. At the same time, warming altered the size structure of microbes towards dominance of small forms. Ordination analyses showed that most important factors determining the occurrence of microbes and small Metazoa are temperature, organic matter, and biogenic compounds. A better understanding of what regulates microbial populations and activity in traps and in water in peatbogs and unraveling of these fundamental mechanisms are particularly critical in order to more accurately predict how peatbogs will respond to climate disturbances.

Restructuring of plankton genomic biogeography in the surface ocean under climate change

The impact of climate change on diversity, functioning and biogeography of marine plankton remains a major unresolved issue. Here environmental niches are evidenced for plankton communities at the genomic scale for six size fractions from viruses to meso-zooplankton. The spatial extrapolation of these niches portrays ocean partitionings south of 60° N into climato-genomic provinces characterized by signature genomes. By 2090, under the RCP8.5 future climate scenario, provinces are reorganized over half of the ocean area considered, and almost all provinces are displaced poleward. Particularly, tropical provinces expand at the expense of temperate ones. Sea surface temperature is identified as the main driver of changes (50%), followed by phosphate (11%) and salinity (10%). Compositional shifts among key planktonic groups suggest impacts on the nitrogen and carbon cycles. Provinces are linked to estimates of carbon export fluxes which are projected to decrease, on average, by 4% in response to biogeographical restructuring. The authors define the global environmental niches of plankton from nano- (viruses) to meso-zooplankton (small metazoans) using metagenomic data. They assess reorganizations under climate change and the environmental drivers of change, with focus on the impacts on nitrogen and carbon fluxes.

Effects of the Invasive Fish Species Ameiurus nebulosus on Microbial Communities in Peat Pools

Disturbances in the functioning of peatlands, due to growing human impact, climate change and the appearance of alien invasive species, are becoming increasingly common. Analysis of trophic relationships in the predator (invasive alien species)–prey system is extremely important for understanding the functioning of peat pools—small water bodies formed in peatlands by peat extraction. These issues are, as yet, very little understood. The aim of this study was to examine the impact of Ameiurus nebulosus, an alien and invasive fish species dominant in these pools, on the microbial communities and small metazoa (phycoflora, bacteria, heterotrophic flagellates, ciliates, and crustaceans) in peat pools. The laboratory experiment included two groups of treatments simulating natural conditions: treatments without fish and treatments with brown bullhead. The water temperature was manipulated as well. The presence of brown bullhead in combination with climate changes was shown to cause a change in the structure of microbial communities. This is reflected in a decrease in the abundance of planktonic crustaceans and an increase in ciliates. The overlapping effects of alien species and gradual climate warming may intensify the eutrophication of peatland ecosystems and the increase in the proportion of cyanobacteria, thereby affecting the carbon cycle in these ecosystems.

Enigma variations: characteristics and likely origin of the problematic surface texture Arumberia, as recognized from an exceptional bedding plane exposure and the global record

AbstractArumberia is an enigmatic sedimentary surface texture that consists of parallel, sub-parallel or radiating ridges and grooves, most commonly reported from upper Neoproterozoic – lower Palaeozoic strata. It has variably been interpreted as the impression of a small metazoan, a ‘vendobiont’, a physical sedimentary structure formed on a substrate with or without a microbial mat covering, or a non-actualistic microbial community. In this paper we contribute new insights into the origin of Arumberia, resulting from the discovery of the largest contiguous bedding plane occurrence of the texture reported to date: a 300 m2 surface in the lower Cambrian Port Lazo Formation of Brittany, NW France. We compare the characteristic features of Arumberia at this locality with 38 other global records, revealing four defining characteristics: (1) the three-dimensional (3D) morphology of exposed Arumberia lines (either positive relief ‘ridges’ or negative relief ‘grooves’) records fully preserved cords within clay laminae; (2) lines may transition laterally into reticulated patterns; (3) characteristic parallel and sub-parallel Arumberia lines can become modified by desiccation on emergent substrates prior to interment; and (4) Arumberia are streamlined with palaeoflow in successions showing evidence of unidirectional currents, but are organized parallel to ripple crests where strata were sculpted by oscillatory flows. These characteristics indicate that Arumberia records a 3D entity, distinct in material properties from its host sediment, which occurred in very shallow water settings where it was prone to passive reorganization in moving water, and desiccation when water drained. A literature survey of all known Arumberia occurrences reveals that the most reliable examples of the form are stratigraphically restricted to a 40 Ma interval straddling the Ediacaran–Cambrian boundary (560–520 Ma). Together these characteristics suggest that Arumberia records the remains of extinct, sessile filamentous organisms (microbial or algal?) that occupied very shallow water and emergent environments across the globe at the dawn of the Phanerozoic Eon.

The diet of Macrogenioglottus alipioi Carvalho, 1946 (Anura: Odontophrynidae) tadpoles in Atlantic Forest of southern Bahia, Brazil

ABSTRACT Understanding the diet of tadpoles is fundamental to explain their ecological roles in aquatic food webs, as well as to allow more effective amphibian conservation and management programs. Studies on trophic ecology of tadpoles are scarce compared to other vertebrate groups, a gap that is even more accentuated in the Neotropical region, which harbors the greatest diversity of anuran species worldwide. The objective of this study was to describe the diet of the tadpole of Macrogenioglottus alipioi, from a population in southern Bahia, Brazil. Gut contents of 30 tadpoles were analyzed under light microscope. Additionally, the intestinal contents of 15 tadpoles were analyzed under a stereoscopic microscope to verify the presence of larger food items such as macroinvertebrates. Algae were the most important microscopic food item in the diet of M. alipioi tadpoles. Mites occurred in 80% of the analyzed specimens and represented the most important macroscopic food source, followed by insect fragments from dipterans, lepidopterans and spiders. The tadpoles of M. alipioi can be considered omnivorous consumers. As in benthic tadpoles from other species, diatoms, protozoans and small metazoans are considered important food sources in the diet of tadpoles. Additionally, the analysis of gut contents under a stereoscopic microscope identified several food items that were not recorded by analyses performed under light microscope.

Meiofauna as a valuable bioindicator of climate change in the polar regions

Establishing robust estimates of polar marine biodiversity is important for interpreting future changes in the Arctic; however, despite a recent increase in scientific expeditions, this region remains relatively underexplored. Particularly overlooked in biodiversity assessments are small species, such as protists, fungi, and many small invertebrates that are collectively known as meiofauna. These species contribute to the foundation of food webs and are crucial for the survival of larger species that are economically and socially important. The application of high-throughput sequencing methodologies has proven effective for biomonitoring small metazoan species but has sparingly been applied in the Arctic. We used a metabarcoding approach to assess the diversity of sea ice and sediment-associated metazoans from Utqiaġvik (Barrow), Alaska. Sea ice and sediment samples were collected six times over eight months (January through August) encompassing three seasons (winter, spring, and summer) from polar night to ice-out in August. Biodiversity was assessed as both richness and community composition by incorporating incidence data and phylogenetic distance. Environmental conditions associated with ice, sediment, water, and snow were measured and tested for possible correlations with biodiversity estimates. We found a high number of taxa distributed locally, suggesting that metabarcoding can be effectively applied to Arctic biomonitoring programs. In addition, these results show that season and habitat are significant predictors of meiofaunal biodiversity, supporting hypotheses that meiofauna can be used as a valuable indicator of climate change.

Nutrient addition increases rotifer abundance and diversity in a temperate bog

Rotifers are among the smallest metazoan animals living in lakes, ponds, rivers and in interstitial water within Sphagnum mats. When in sufficient numbers they are capable of regenerating large amounts of nitrogen (N) as NO3 and NH4 and phosphorus (P) as PO4; all of these nutrients are immediately available to bog plants. The ecological role of rotifers in bog ecosystems has been recognized at both local and global scales, but the effect of N and P addition on rotifers in bogs remains unknown. Here we present data on the influence of N and P addition on rotifers at a temperate Canadian bog dominated by Sphagnum mosses. We found that rotifer species abundance and diversity were significantly higher in surficial pore water after long-term exposure to increased N and P addition than in the control. A change in plant species distribution and increased rotifer abundance may partly explain the faster decomposition rates, jeopardizing the carbon sink capacity of bogs.

New occurrence of the Guanshan Lagerstätte (Cambrian Series 2, Stage 4) in the Kunming area, Yunnan, southwest China, with records of new taxa

As a classic Burgess-Shale-Type Konservat-Lagerstätte, the Guanshan biota is well known for its abundant soft-bodied fossils with high taxonomic diversity. Here, we report a new locality of the Guanshan biota in the Kunming area, Yunnan, South China with several new forms being first documented. In particular: a naraoiid euarthropod, the dorsal exoskeleton of which has characters of both naraoiids and Emucaris; and a discoidal animal, identified as a small eldonioid-like metazoan, which has a counterpart from the Emu Bay Shale Lagerstätte of South Australia, and which further strengths the biogeographic connection between the early Cambrian biotas of South China and Australia. Our new discoveries not only expand the palaeogeographic distribution of the Guanshan biota, but also reveal that its biodiversity is much higher than previously thought, and can be justifiably regarded as a community successor to the Chengjiang biota.Jun Zhao [zhaojunpaleo@126.com], Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; Yunnan Key Laboratory of International Rivers and Transboundary Eco-Security, Yunnan University, Kunming 650091, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; Yujing Li [yujingli@ynu.edu.cn], Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; Paul A. Selden [selden@ku.edu], Department of Geology, University of Kansas, 1457 Jayhawk Boulevard, Lawrence, KS 66045, USA; Natural History Museum, Cromwell Road, London SW7 5BD, UK; Peiyun Cong [cong@ynu.edu.cn], Yunnan Key Laboratory for Palaeobiology, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China; MEC International Joint Laboratory for Palaeobiology and Palaeoenvironment, Institute of Palaeontology, Yunnan University, Kunming, Yunnan, 650091, China.

Potentially combined effect of the invasive seaweed Caulerpa cylindracea (Sonder) and sediment deposition rates on organic matter and meiofaunal assemblages

The seaweed Caulerpa cylindracea (Sonder) is one of the most successful marine bioinvaders worldwide. Caulerpa cylindracea can influence the quantity and biochemical composition of sedimentary organic matter (OM). However, it is still unknown if the effects of C. cylindracea on both OM and small metazoans (i.e. meiofauna) can change according to different sediment deposition rates. To provide insights on this, we investigated the biochemical composition of sediments along with the abundance and composition of meiofaunal assemblages in sediments colonized and not-colonized by the seaweed C. cylindracea under different regimes of sediment deposition. Our results show that the presence of the invasive alga C. cylindracea could alter quantity, biochemical composition, and nutritional quality of organic detritus and influence the overall functioning of the benthic system, but also that the observed effects could be context-dependent. In particular, we show that the presence of C. cylindracea could have a positive effect on meiofaunal abundance wherever the sediment deposition rates are low, whereas the contextual presence of high to medium sedimentation rates can provoke an accumulation of sedimentary organic matter, less favourable bioavailability of food for the benthos, and consequent negative effects on meiofauna.

New Reports of Gastrotricha for the North-Eastern Ukraine

Gastrotricha is poor known phylum of small metazoans. Information about Ukrainian gastrotrichs’ fauna is old. In total 9 species are reported in this paper. Chaetonotus (Hystricochaetonotus) hystrix, Chaetonotus (Primochaetus) heideri,Chaetonotus (Zonochaeta) bisacer, Lepidodermella minor minor, Lepidodermella squamata, Ichthydium maximum and Haltidytes festinans are new to the Ukraine fauna. This investigation is giving also additional information for Chaetonotus (Chaetonotus) maximus, Chaetonotus(Hystricochaetonotus) macrochaetus, which have been previously reported to the Ukraine fauna but are new for Kharkiv oblast. We provide short description of all species and some ecology aspects.

Impact of Peatland Restoration on Soil Microbial Activity and Nematode Communities

Urban and industrial developments were the reason for draining peatlands in the past which caused changes in their ecology. Restoration of the water regime aims to bring back their original functions. This study examines the natural recovery of peatland following re-wetting, blocking the drainage ditches. We used soil microbial activity, physicochemical properties and nematode communities as indicator taxa to describe restoration status five years after management. Data were compared to those obtained from adjacent degraded forest and meadow like habitats of former peatlands. Our results indicate that re-wetting had considerable effect to soil indices and nematodes. Soil moisture and organic carbon significantly increased, while pH has not changed. In contrast, soil enzymatic activity significantly decreased after re-wetting in the restored part of the peatland compared to the degraded habitats. These conditions were probably less favourable for small metazoans, because of their abundance; species number and diversity were significantly decreased after re-wetting management. The nematode trophic structure was also significantly degraded; the restored part of peatland had less omnivore and predators as well as plant parasites. We conclude that in respect to both biological indicators and basic soil properties analysed, blocking of drainage ditches creates capable conditions for natural peatland restoration.

Microbial Metazoa Are Microbes Too.

Microbial metazoa inhabit a certain "Goldilocks zone," where conditions are just right for the continued ignorance of these taxa. These microscopic animal species have body sizes of <1 mm and include diverse groups such as nematodes, tardigrades, kinorhynchs, loriciferans, and platyhelminths. The majority of species are too large to be considered in single-cell genomics approaches, yet too small to be wrapped into international genome sequencing initiatives. Other microbial eukaryote groups (namely the fungal and protist communities) have gained significant momentum in recent years, driven by a strong community of researchers united behind a common goal of culturing and sequencing new representatives. However, due to historical factors and difficult taxonomy, persistent research silos still exist for most microbial metazoan groups, and public molecular databases remain sparsely populated. Here, I argue that small metazoa should be embraced as a key component of microbial ecology studies, promoting a holistic and cutting-edge view of natural ecosystems.

Treatments of Wastewater in Rural Communities Using a Pilot Plant Photobioreactor

In order to avoid eutrophication phenomena of surface water-courses, the reduction of the nutrient content, such as nitrogen and phosphorus, becomes ever more pressing. Respect to traditional depuration systems, the phytodepuration by microalgae presents different advantages: the simultaneous reduction of nitrogen and phosphorus by photosynthesis with biomass production without external organic sources and the production of oxygenated effluents after microalgae treatment. Moreover, the produced biomass could be used as raw material for energy or chemical purposes and the depuration systems with microalgae require less surface area than traditional phytodepuration ones. In this work data recovered from phytodepuration of rural municipal waste by microalgae are presented. Microalgae were grown in a semi-pilot photobioreactor system with a total capacity of 0.95 m3, consisting of: a photobioreactor composed by 40 vertical plexiglass tubes fed in parallel, a recycling vessel with a volume of 500 L, a recycling centrifugal pump and a submerged centrifugal feed pump. The area occupied by the plant was 5.4 m2. The photobioreactor was continuously fed with the final effluent of San Pietro Vara (Imperia, Italy) wastewater treatment plant and the effluent from the photobioreactor was piped in the no-longer used sludge draining bed, and from here in the feed sump. The microalgae growth has been identified by microscopic analysis. The predominant algal species were Chlorophyceae and Cyanophyceae, but the total biomass included also protozoa and small metazoan. Biomass concentration was recorded periodically. Two multiparamentric probes were used for the determination of pH, OD, NO3, NH4+, Chlorophyll-a, temperature and turbidity, while COD, total N and P were measured traditionally. The main results obtained from the closed system have been average removal of 50, 60 and 50 % for COD, total N and total P respectively. Results indicated that, in general, the outlet of phytodepuration met the quality standards required by law (Annex 5 – Italian Law 152/06 according to the EC Dir. 91/271).