Abiotic Parameters Research Articles

Effects of repeated sediment bypassing on stream ecosystems in a Japanese mountainous river

Sediment bypassing connects the upstream and downstream regions of dam impoundments through tunnels and is expected to partly restore natural processes (flood pulse and sediment regime) in dam‐altered river ecosystems. However, few reports examined the effects of restoration on stream biota. We examined the effectiveness of repeated sediment bypassing (12 times) over a period of 5 years in a Japanese dammed river using a before‐after‐reference‐impact design. We compared the abiotic parameters (water quality and substrate environment), biotic assemblages (algae, macroinvertebrates, and fish), and similarities between the dam downstream and undammed reference reaches. The reference sites exhibited high temporal variability in abiotic environments and species composition over the 5‐year period. Most abiotic and biotic parameters downstream of the dam improved and approached those of the changing reference states. However, these indices returned to pretrial conditions after the last trial. Biotic similarities between the downstream and reference reaches gradually increased throughout successive sediment‐bypassing trials for macroinvertebrates and algae; however, these similarities diminished after the last trial. Conversely, the abundance‐based composition of fish assemblages in the restored reach consistently diverged from that of the reference conditions throughout the study period. Our results show that the success and failure of restoration by sediment bypassing may be affected by the amount of bedload in the flushing flows and other regional processes such as migratory connectivity. Sediment bypassing can partially re‐establish natural processes and is a useful tool for improving sediment‐associated environments and biota.

Habitat and benthic community correlates of Epeorus longimanus (Ephemeroptera: Heptageniidae) microdistribution in a Colorado, USA, stream riffle

Abstract Little is known about the ecology of early instars of most aquatic insects, particularly their associations with microhabitat (<1 m2) features, such as sediment size distributions, other abiotic parameters, and the overall invertebrate community. This study sought to explore correlations between various biotic and abiotic parameters of a southern Colorado stream and the presence of early instars of Epeorus longimanus (Eaton) (Ephemeroptera: Heptageniidae). A total of 18 samples collected in 2007 and 2013 using a Hess sampler in riffle habitats were used to correlate the size of individuals with biological and abiotic characteristics of the stream, including sediment size, periphyton biomass, entrained organic matter, and the remainder of the benthic invertebrate community, all of which were measured using material from within the sampler. Results from both years showed that early instars of E. longimanus were more likely to be found in areas with smaller sediment sizes, higher live periphyton biomass (but lower overall organic matter), and lower densities of invertebrate predators.

Effect of Abiotic Factors on the Population Dynamics of Red Spider Mite, Tetranychus urticae Koch. of Brinjal in Malwa Region, Madhya Pradesh, India

Field experiments were conducted to investigate the population dynamics of the red spider mite (Tetranychus urticae Koch) in brinjal and its relationship with various abiotic parameters during the 2020 and 2021 crop seasons at Patan farm, Krishi Vigyan Kendra, Mandsaur, Malwa region of Madhya Pradesh. The findings indicated that the red spider mite population initiated in the 30th and 31st standard weeks in 2020 and 2021, respectively. The peak population of mites per 2 cm2 leaf area was observed in the 43rd standard week (11.52) in 2020, while the highest population was noted in the 41st standard week (9.91) in 2021. It was evident that mite infestation was substantial during October in both years. There was a noteworthy positive correlation between the population of predatory mites, maximum temperature, and sunshine hours with the red spider mite pest, while a negative correlation was observed with relative humidity.

Soil pH influences the toxicity of Basamid® eluates to non-target species of primary consumers

Basamid® is a fumigant nematicide and fungicide known to break down in several volatile compounds, mainly methyl isothiocyanate (MITC), when in contact with water. Soil abiotic parameters, such as pH, influences this breakdown process, and thus, the toxic effects of Basamid® to aquatic biota. This work studied the influence of soil pH (5.5, 6.5 and 7.5) on the toxicity of eluates (1:4, m:v), obtained from Basamid®-contaminated soils (with the recommended dose of 145 mg of dazomet/Kg of soil), on two primary consumers: Daphnia magna and Brachionus calyciflorus. For this, lethal and sublethal toxicity of eluates originated from soils at pH 5.5, 6.5 and 7.5, contaminated with Basamid® (Ba-E 5.5; 6.5 and 7.5, respectively), were assessed (dilutions between 0.096 - 100%). The LD50,24h of Basamid® eluates for D. magna varied from 3.07% to 7.82% (Ba-E 6.5 and Ba-E 5.5 respectively), while for B. calyciflorus varied from 18.1% to 84.7% (Ba-E 6.5 and Ba-E 7.5, respectively). Both species were less sensitive to Basamid® eluates originated from soils with pH 7.5 and more sensitive to those obtained from soils with pH 6.5. Regarding the sublethal effects, a lower soil pH was associated with a higher toxicity of Basamid® to D. magna reproduction (LOED: 0.125% Ba-E 5.5), while for B. calyciflorus such a higher toxicity was observed at the highest soil pH (ED20: 7.42% [5.10-9.74] at Ba-E 7.5). These results show a negative association between soil pH and the lethal toxicity of Basamid® contaminated eluates. However, such a pattern was not observed at sublethal level, at which a species dependency was observed regarding the influence of soil pH in the observed toxicity. Nevertheless, it is to highlight that very low concentrations of eluates (as 3.07%) caused significant mortality, indicating a high risk for freshwater biota. Considering that Basamid® is likely to reach the aquatic systems is real, for which reason the recommended dose must be reviewed at environmentally-relevant scenarios.

Influence of Some Abiotic Factors on the Diatom Densities in the Mezam River (Bamenda, North-West Cameroon)

Wetlands of the city of Bamenda are characterized by intense agricultural activities. The resulting consequences are aquatic pollution. The management of these wetlands requires the study of the animal and plant communities found there. Diatoms are known to be good markers of environmental change. The aim of the study was to determine the influence of some abiotic parameters on the diatom densities of the Mezam river. The study was conducted from January to December 2022. Some physicochemical parameters were measured in situ. Water samples were collected and transported to the laboratory for the measurement of nitrates, total phosphorus, carbon dioxide and biological oxygen demand. The diatoms were sampled and analyzed in the laboratory. Factorial axis 2 (0.47%) of correspondence factor analysis opposed the positive variables (conductivity, total dissolved solids and salinity) to the negative variables (water temperature, pH, nitrates, total phosphorus, oxidability, carbon dioxide and alkalinity). Study sites showed a mineralization gradient going from upstream (Site 1) to downstream (Site 3). Total species richness amounted to 4 classes divided in 18 families, 21 genera and 43 species. The most dominating family was Naviculaceae with 10 species. Multiple component analysis showed, in different study sites, the correlation between chemical parameters and density of different genera. The more the site was polluted, the more the density of Navicula, Tabellaria, Melosira and Coscinodiscus increased. On the contrary, the less the site was polluted, the more the density of Cyclotella, Gomphonema, Cocconeis, Gyrosigma, Synedra increased. These results showed that the distribution of diatoms in the different study sites was influenced by a set of conditions related to physicochemical parameters, but more on their densities.

Drivers of cultivated and wild plant pollination in urban agroecosystems

Pollination is a vital ecosystem service in urban agriculture. Yet the environmental drivers of both crop and wild plant pollination in urban agroecosystems are still not well understood. Pollination experiments involve the manipulation of pollen transfer between plants, for instance, to study the effects of pollinators on fruit and seed production (pollination service). In this study, we conducted a pollination exclusion experiment using four experimental plants: two cultivated plant species, strawberry (Fragaria x ananassa) and chili pepper (Capsicum frutescens), and two wild plant species, buttercup (Ranunculus acris) and clover (Trifolium pratense). We placed experimental plants for over 20 days in 13 urban community gardens in Munich, Germany. We compared fruit and seed mass between “open” and “bagged” flowers and tested the effect of biotic factors (floral resources and pollinator diversity) and abiotic factors (urbanization, microclimate) on pollination service (fruit and seed mass) on the experimental plant species. For the two cultivated plants (F. ananassa and C. frutescens), we found that fruit and seed mass were both positively correlated with temperature and pollinator diversity. For the two wild plants (R. acris and T. pretense), we found that floral abundance was negatively related to R. acris seed mass but was positively related to T. pratense seed mass. In summary, we found that biotic and abiotic parameters affected the plant species studied here in different ways, suggesting that there may be synergies and trade-offs in what factors promote the overall pollination of urban plant communities. Our results suggest that gardeners can potentially increase the pollination services on certain garden plants by providing floral resources for pollinating insects.

Impacts of abiotic factors on the growth of three commercial biological control agents, on the growth and mycotoxinogenesis of Fusarium graminearum and on their interaction.

Evolving climatic conditions impact the behavior of microorganisms. The lack of efficiency of beneficial microorganisms against pathogens can be due to these evolving abiotic factors more favorable to the development and adaptation of pathogens. It is therefore of great interest to understand their impact (especially temperature increase and relative humidity (RH) variation) on pathogenic and non-pathogenic microorganisms. This work aimed to examine the possible effects of increasing temperature (20, 25, 30 and 33 °C) and RH (40%, 50%, 60% and 80%) on the growth and mycotoxin production (deoxynivalenol (DON) and zearalenone (ZEN)) of Fusarium graminearum, on the growth of three commercial biocontrol agents (BCAs; Mycostop®, Xedavir® and Polyversum®) and on the pathogen-BCA interaction. Results demonstrated that BCAs have contrasting impacts on the growth and mycotoxinogenesis of F. graminearum depending on abiotic factors. At 25 °C and regardless of RH, commercial BCAs limit DON production by F. graminearum, but at 30 °C and intermediate RH, Xedavir® is no longer effective. The ability of Xedavir® to control the production of ZEN production by F. graminearum is also affected by abiotic factors. However, increasing temperature has an opposite effect on its ability to control the accumulation of ZEN. Polyversum® oomycete is the BCA with the most resilient efficacy against F. graminearum toxinogenesis under the different abiotic factors. This work provides new knowledge of the effect of these abiotic parameters on the interaction between BCA and F. graminearum, especially on the production of mycotoxins. It paves the way for the development of efficient and resilient mycotoxin biocontrol strategies using beneficial microorganisms against F. graminearum, thus contributing to global food security. © 2023 Society of Chemical Industry.

Assessment of total coliforms and E. coli removal in algae-based pond under tropical temperature in addition of carbon dioxide (CO2) and shading

The present work aimed to investigate the effects of adding CO2 to the treatment carried out by native microalgae in a raceway pond with high load sewage to remove E. coli and total coliforms, as well as to evaluate the influence of shading on the treatment system operated on a pilot scale, outdoors under actual conditions in real time analysis. There were significant correlations between total coliforms and E. coli removals with abiotic parameters such as pH and dissolved oxygen. From the results, it was observed that in the experiments without shading the removal of total coliforms and E. coli were better. It can be concluded that they were factors acting synergistically for the success of the pathogenic removal of coliforms and this may be the occurrence of endogenous photo-oxidation and oxidative stress in microbial cell leads to DNA damage and cell death due inactivate the metabolic growth of the cells. Further, the final effluent generated by the pond cannot be used for direct reuse, a post-treatment is necessary to fit within the established limits so as to increase the possibilities of its reuse.

Exploration of Ichthyofaunal Diversity in Beas River Near Nadaun Region of Himachal Pradesh, India

The present research paper deals with studies on fish-faunal diversity in relation to abiotic parameters in the Beas River near Nadaun region of Himachal Pradesh state in India. A total of 12 fish species belonging to 6 orders and 7 families were recorded during the present study. Cypriniformes was the dominant order represented by 7 species. According to IUCN, out of 12 species, 9 species were recorded under the Least Concern (LC) category whereas 1 species each was included in Vulnerable (VU), Endangered (EN) and Not-Evaluated (NE) category respectively. Role of selected physicochemical parameters (Water temperature, PH, Dissolved Oxygen (DO), Total Dissolved Solids (TDS) and Electric current) of river water in governing distributional pattern of fish-fauna was analyzed specifically by Redundancy Analysis (RDA) method. Threats and strategies to conserve fish faunal diversity are also suggested.

Nature reserves (zapovedniks) in the Volga catchment: protection, research and management

AbstractIn the Russian Federation, the protection category “Zapovednik” represents a strictly protected area, where the access is restricted and the aim is to keep the area “forever wild”. We provide an overview about the organization of these nature reserves and highlight their contribution to fundamental research. Aquatic ecosystems in zapovedniks provide pristine sites of great importance for long-term monitoring and research, which fosters process understanding regarding interannual variability and development of aquatic coenosis. We present a long term monitoring and research project about abiotic and biotic parameters in the Central Forest State Nature Biosphere Reserve. Examples from the Privolzhskaya Lesostep Nature Reserve include monitoring of invasive fish as well as analyses about the influence of beavers on fish. The Astrakhan Biosphere Nature Reserve in the Volga delta is a hotspot for fish biodiversity; thus, there the state nature reserve security service plays an important role to avoid poaching. Our case studies from the Volga Basin exemplify the structure and function of nature reserves and highlight their contribution to research, protection and management of aquatic ecosystems. Long-term datasets from the zapovedniks can (i) improve process understanding, (ii) ensure protection of aquatic systems and sustainable water management and (iii) support knowledge-based decisions.

Patterns of high-flying insect abundance are shaped by landscape type and abiotic conditions

Insects are of increasing conservation concern as a severe decline of both biomass and biodiversity have been reported. At the same time, data on where and when they occur in the airspace is still sparse, and we currently do not know whether their density is linked to the type of landscape above which they occur. Here, we combined data of high-flying insect abundance from six locations across Switzerland representing rural, urban and mountainous landscapes, which was recorded using vertical-looking radar devices. We analysed the abundance of high-flying insects in relation to meteorological factors, daytime, and type of landscape. Air pressure was positively related to insect abundance, wind speed showed an optimum, and temperature and wind direction did not show a clear relationship. Mountainous landscapes showed a higher insect abundance than the other two landscape types. Insect abundance increased in the morning, decreased in the afternoon, had a peak after sunset, and then declined again, though the extent of this general pattern slightly differed between landscape types. We conclude that the abundance of high-flying insects is not only related to abiotic parameters, but also to the type of landscapes and its characteristics, which, on a long-term, should be taken into account for when designing conservation measures for insects.

Abiotic dynamics in an area of occurrence of the golden mussel: Limnoperna fortunei (Dunker, 1857), in a stretch of the Rio Grande

Physical-chemical parameters can influence the distribution of organisms in space and time. Limnoperna fortunei, a bivalve originating in China, is an example of an organism with high plasticity and wide geographic distribution. A decade after its introduction in the Rio Grande Basin, studies of physicochemical parameters are still scarce. Thus, the objective of this work is to describe the dynamics of physical-chemical parameters in the Lower Rio Grande Basin. For this, the physical-chemical parameters were analyzed: temperature; pH; oxidation potential; Electric conductivity; turbidity; dissolved oxygen and total dissolved solids. A Principal Components Analysis; and a Non-Metric Scaling Analysis were performed. Finally, to verify significant abiotic differences between the points, a comparative analysis was performed. The study demonstrated that even with the effects of seasonality acting on the points, the two stretches of the Lower Rio Grande Basin showed similarity in the abiotic parameters, reflecting environmental stability; what may be positively influencing the population stabilization of Limnoperna fortunei.

Early assessment of effects of dam removal on abiotic fluxes of the Selune River, France

The Water Framework Directive set for European Union countries the objective of restoring the ecological and/or sediment continuity of rivers, as the latter is relevant for providing suitable habitats for the former. Indeed, abiotic fluxes and variables shape riverine ecological habitats and are likely to be modified by barriers such as dams. Two dams were removed from the Selune River (northwestern France) from spring 2017 to summer 2022. The objective of this study was to describe and quantify how the dams modified abiotic parameters and fluxes, as well as the dynamics of these fluxes during dam removal. We monitored coarse and fine sediments, water temperature and nutrient concentrations in the Selune River from upstream to downstream of the dams from 2015 to 2023. The results showed that coarse sediments of the riverbed are a legacy and that current hydrodynamic conditions are not sufficient to move them much, with or without the dams. In addition, it appears that at this early stage after the removal some downstream parameters, especially nutrient concentrations and water temperature, have already converged towards upstream signals, while fine sediment stored in the dam’s reservoirs are still destocking. Restoring ecological continuity of the Selune River will involve dynamics of abiotic parameters over longer time scales, in response to removal of the dams, and over larger spatial scales, in response to climate and other global changes.

Spatial and Temporal Variation of Fish Assemblage Associated with Aquatic Macrophytes in Three Small Lagoons of the SOUTH-Eastern, Côte d’Ivoire

Aquatic plants play a crucial role in an aquatic ecosystem partly because these plant communities provide suitable habitats and food items to other aquatic organisms especially fish. The purpose of the present study was to examine spatial variation in fish assemblage structure associated with aquatic macrophytes in Ono, Kodjoboue and Hebe lagoons, three small lagoons of Côte d’Ivoire. Fish were monthly sampled from September 2014 to August 2016 using traps, gill nets, harpoons and hawks. The abiotic parameters namely temperature, transparency, pH, total dissolved solids, conductivity, dissolved oxygen, ammonium-nitrogen, nitrate, nitrite and phosphate were recorded for the characterization of the water mass in the lagoons. Significant variation in water parameters was observed among the sampling lagoons, except for nitrite and ammonium-nitrogen. However, no significant different was obtained between Kodjoboue and Hebe lagoons. A total of 42, 35 and 37 species were recorded respectively in Ono, Kodjoboue and Hebe lagoons, with Perciformes (22 species), Siluriformes (8 species) and Osteoglossiformes (7 species) being the most diverse Orders. Habitats with highly amounts of macrophyte cover provide the optimal environment for many fish and hence, increase the taxonomic richness, abundance, diversity and equitability. The multivariate analysis showed that temperature, dissolved oxygen, nitrate, phosphate, pH and ammonium-nitrogen and macrophyte were key environmental variables and played important roles in determining species composition of fish assemblages.

Impact of Abiotic Factors on Population Dynamics of Leaf Miner, Aproaerema modicella D. and Its Natural Enemies in Groundnut

Groundnut leaf miner (Aproaerema modicella. D.) is an important leaf feeding insect in groundnut that significantly reduces the pod yield up to 50 per cent. The growth and development of this insect pest is closely associated with the abiotic weather parameters prevailing in a particular location. Due to paucity of information available on the population dynamics of groundnut leaf miner with abiotic weather factors, a study was undertaken in Erode district of Tamil Nadu during Summer, 2023. Groundnut leaf miner damages were recorded through the fixed plots survey and the adult moth activities were monitored through pheromone traps at weekly intervals. From this study it was found that, the leaf miner incidences were observed from 30 days after sowing. The highest mean leaf miner mean damage (17.84%), pheromone adult catches (58.38 nos./5 traps), coccinellid beetle population (4.70 nos./10 plants) and spider population (5.17 nos./10 plants) were observed during 9th SMW. Whereas, the rove beetle population was maximum (4.62 nos./10 plants) during 10th SMW. The correlation study revealed that the maximum temperature had positive correlation and rainfall had negative correlation with the populations of groundnut leaf miner and its natural enemies. The multiple linear regression analysis indicated that the weather parameters together had 66.00 to 95.00 per cent influence on the groundnut leaf miner and its natural enemy population. The present study clearly indicated that, the population of groundnut leaf miner and its damage levels were closely related to the abiotic weather parameters prevailed in the study area during entire crop duration. Better understanding of the weather factors resulted in better leaf miner management and more net profit for the groundnut growers.

Uncovering the Grinnellian niche space of the cryptic species complex Gammarus roeselii.

The discovery of cryptic species complexes within morphologically established species comes with challenges in the classification and handling of these species. We hardly know to what extent species within a species complex differ ecologically. Such knowledge is essential to assess the vulnerability of individual genetic lineages in the face of global change. The abiotic conditions, i.e., the Grinnellian niche that a genetic lineage colonizes, provides insights into how diverse the ecological requirements of each evolutionary lineage are within a species complex. We sampled the cryptic species complex of the amphipod Gammarus roeselii from Central Germany to Greece and identified genetic lineages based on cytochrome c oxidase subunit I (COI) barcoding. At the same time, we recorded various abiotic parameters and local pollution parameters using a series of in vitro assays to then characterize the Grinnellian niches of the morphospecies (i.e., Gammarus roeselii sensu lato) as well as each genetic lineage. Local pollution can be a significant factor explaining current and future distributions in times of increasing production and release of chemicals into surface waters. We identified five spatially structured genetic lineages in our dataset that differed to varying degrees in their Grinnellian niche. In some cases, the niches were very similar despite the geographical separation of lineages, supporting the hypothesis of niche conservatism while being allopatrically separated. In other cases, we found a small niche that was clearly different from those of other genetic lineages. The variable niches and overlaps of different dimensions make the G. roeselii species complex a promising model system to further study ecological, phenotypic and functional differentiation within this species complex. In general, our results show that the Grinnellian niches of genetically distinct molecular operational taxonomic units (MOTUs) within a cryptic species complex can differ significantly between each other, calling for closer inspection of cryptic species in a conservational and biodiversity context.

Planophila laetevirens-Mediated Synthesis of Silver Nanoparticles: Optimization, Characterization, and Anticancer and Antibacterial Potentials.

Algal-mediated synthesis of nanoparticles (NPs) opens the horizon for green and sustainable synthesis of NPs that can be used in many fields, such as medicine and industry. We extracellularly synthesized silver NPs (Ag-NPs) using the novel microalgae Planophila laetevirens under optimized conditions. The isolate was collected from freshwater/soil, purified, morphologically identified, and genetically identified using light, inverted light, scanning electron microscopy, and 18S rRNA sequencing. The phytochemicals in the algal extract were detected by GC-MS. Aqueous biomass extracts and cell-free media were used to reduce silver nitrate to Ag-NPs. To get small, uniformly shaped, and stable Ag-NPs, various abiotic parameters, including precursor concentration, the ratio between the reductant and precursor, temperature, time of temperature exposure, pH, illumination, and incubation time, were controlled during the synthesis of Ag-NPs. B-P@Ag-NPs and S-P@Ag-NPs (Ag-NPs synthesized using biomass and cell-free medium, respectively) were characterized using UV-vis spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray analysis (EDX) and mapping, Fourier transform infrared (FTIR) spectroscopy, and a zeta sizer. S-P@Ag-NPs had a smaller size (10.8 ± 0.3 nm) than B-P@Ag-NPs (19.0 ± 0.6 nm), while their shapes were uniform quasispherical (S-P@Ag-NPs) and spherical to oval (B-P@Ag-NPs). EDX and mapping analyses demonstrated that Ag was the dominant element in the B-P@Ag-NP and S-P@Ag-NP samples, while FTIR revealed the presence of O-H, C-H, N-H, and C-O groups, indicating that polysaccharides and proteins acted as reductants, while polysaccharides/fatty acids acted as stabilizers during the synthesis of NPs. The hydrodynamic diameters of B-P@Ag-NPs and S-P@Ag-NPs were 37.7 and 28.3 nm, respectively, with negative charges on their surfaces, suggesting their colloidal stability. Anticancer activities against colon cancer (Sw620 and HT-29 cells), breast cancer (MDA-MB231 and MCF-7 cells), and normal human fibroblasts (HFs) were screened using the MTT assay. B-P@Ag-NPs and S-P@Ag-NPs had a greater antiproliferative effect against colon cancer than against breast cancer, with biocompatibility against HFs. The biocidal effects of the B-P@Ag-NPs and S-P@Ag-NPs were evaluated against Escherichia coli, Bacillus cereus, and Bacillus subtilis using agar well diffusion and resazurin dye assays. B-P@Ag-NPs and S-P@Ag-NPs caused higher growth inhibition of Gram-negative bacteria than of Gram-positive bacteria. B-P@Ag-NPs and S-P@Ag-NPs synthesized by P. laetevirens are promising antitumor and biocidal agents.

Tetrodotoxin in bivalve mollusks: An integrated study towards the comprehension of the influencing factors of a newly native phenomenon

Tetrodotoxins (TTXs) are potent neurotoxins named after the Tetraodontidae fish family. The ingestion of TTX-contaminated flesh can cause neurotoxic symptoms and can lead to death. In 2017 symptoms the European Food Safety Authority (EFSA) recognized the threat to food safety resulting from TTX exposure via food consumption and, thus, proposed a safety limit of 44 μg/kg of TTX in marine gastropods and bivalves. To date, however, TTXs have not yet been included in the list of biotoxins to be monitored within the European Union, even though, in a few cases, levels of TTX found were higher than the EFSA limit. The origin of TTX production is debated and the roles of both biotic and abiotic factors on TTX-mediated toxic events remain unclear. In order to meet these knowledge requests the present study was aimed to investigate the role of seawater temperature, pH, water conductivity, and oxygen saturation, along with the marine phytoplankton community and the bacterial community of mussels and oysters on the accumulation of TTX and analogues in the bivalves. Abiotic parameters were measured by means of a multi-parametric probe, phytoplankton community was analyzed by optic microscopy while microbial community was described by amplicon metataxonomic sequencing, TTXs concentration in the collected matrices were measured by HILIC-MS/MS.A possible role of seawater pH and temperature, among the investigated abiotic factors, in regulating the occurrence of TTXs was found. Regarding biotic variables, a possible influence of Vibrio, Shewanella and Flavobacteriaceae in the occurrence of TTXs was found. Concurrently, Prorocentrum cordatum cell numbers were correlated to the incidence of TTX in mussels. The results herein collected suggest that environmental variables play a consistent part in the occurrence of TTX in the edible bivalve habitats, and there are also indications of a potential role played by specific bacteria taxa in association with phytoplankton.

Comparable early-stage decomposition but contrasting underlying drivers between surface and cave habitats along an elevational gradient

Decomposition is a major contributor to ecosystem respiration, determining the carbon emission and nutrient cycling rates. Our current understanding of decomposition dynamics and their underlying drivers has mainly focused on surface habitats but largely ignored in subterranean environments. Here we studied abiotic and microbial drivers of early-stage litter decomposition inside and outside caves along an elevational gradient in Tenerife. We found comparable decomposition rates (k) and litter stabilizing factors (S), with contrasting drivers and elevational variation. At the surface, we observed a mid-elevational trend in k, which tended to correlate with water availability, cooler temperatures, nutrient availability, and surface-specific bacterial taxa. In sharp contrast, caves showed no elevational impact nor influence of abiotic parameters and bacterial communities on k. Despite this, we found higher levels of S in caves, which were associated mainly with reduced water availability, lower temperatures and cave-specific bacterial taxa, indicating that conditions in caves are strongly linked with carbon storage. Our findings imply that our current perception of terrestrial habitat-based carbon cycling are underestimating the net carbon budget in areas with caves. Disentangling the role of the environment on decomposition in caves is key to fully characterize their roles in nutrient cycling and to understand how increasing anthropogenic pressures will affect fundamental processes in subterranean ecosystems.

Study of the key biotic and abiotic parameters influencing ammonium removal from wastewaters by Fe3+-mediated anaerobic ammonium oxidation (Feammox)

The release of ammonia (as NH4+) into water bodies causes serious environmental problems. Therefore, the removal of ammonia from wastewater effluents has become a worldwide concern. New autotrophic biological alternatives for ammonia removal could reduce the limitations of conventional organic carbon-dependent nitrification-denitrification methods. Here, the potential of anaerobic ammonium oxidation coupled to Fe3+ reduction (a process known as Feammox) is studied in wastewater treatment plants of the yeast and beer production industry, not related to ammonium or iron treatment. This process is presented as a viable option to improve the efficiency of ammonia removal from wastewater. The results of this study show that enrichments under Feammox conditions achieved removals of 28.19–32.25% of the total NH4+. The highest rates of ammonium removal and Fe3+ reduction were achieved using FeCl3 as iron source and pH = 7.0. Different environmental conditions for the enrichments were studied and it was found that the use of sodium acetate as a carbon source and an incubation temperature of 35 °C presented higher rates of iron reduction and higher increase in nitrate concentration, related to ammonium oxidative processes. Likewise, the presence of relevant species of the iron and nitrogen cycles as Ferrovum myxofaciens, Geobacter spp, Shewanella spp, Albidiferax ferrireducens and Anammox was verified, supporting the findings of this study. These results provide information that may be relevant to the potential applicability of Feammox to treat wastewater with high ammonia load and could help develop cost-effective and environmentally friendly methods for ammonium removal in wastewater treatment plants.