Confocal 3D Research Articles

Effect of autogenous shrinkage on microcracking and mass transport properties of concrete containing supplementary cementitious materials

It is well-known that supplementary cementitious materials (SCMs) and low water-to-binder (w/b) ratio increase autogenous shrinkage, but the impact on microcracking and long-term transport properties is less understood. This paper examines the effect of microcracking induced by autogenous shrinkage on transport properties of concretes cured up to ~3.6 years. Variables include SCM type (9% SF, 70% GGBS), w/b ratio (0.20–0.45), maximum-aggregate-size (MSA: 5–20 mm) and shrinkage reducing admixture (SRA). Oxygen diffusivity, permeability and water sorptivity were correlated with microcracks characterised using laser scanning confocal microscopy and 3D X-ray microtomography. Results show greater microcracking in mixes containing SCMs, low w/b ratio and large MSA. At the same w/b ratio and binder type, strong positive correlations are observed between transport and microcracking with increasing MSA, confirming the negative impact of autogenous shrinkage. SRA was effective in reducing these effects. The significance is compared with drying shrinkage and implications for durability are discussed.

A novel chromatic confocal one-shot 3D measurement system based on DMD

Aiming at the problem of low measurement efficiency of conventional single-point chromatic confocal technology, a one-shot chromatic confocal measurement system based on DMD (Digital Micromirror Device) is presented in this paper. This system was set up by applying a polychromatic light source, a color camera, a dispersive lens, and DMD. Firstly, the DMD was used to modulate the polychromatic light source to obtain a point light array. Secondly, a series of focal points were generated by the dispersive lens, and the corresponding relationship between color information and height was established. Lastly, by using an optimized HSI model, the height information of the sample could be obtained, and a 3D profile could be reconstructed accordingly. The experimental data showed that the proposed system can measure and restore the 3D topography of the measured surface by one-shot photography, and the measurement accuracy can reach the micron level.

The evolution of image guidance in robotic-assisted laparoscopic prostatectomy (RALP): a glimpse into the future.

To describe the innovative intraoperative technologies emerging to aid surgeons during minimally invasive robotic-assisted laparoscopic prostatectomy. We searched multiple electronic databases reporting on intraoperative imaging and navigation technologies, robotic surgery in combination with 3D modeling and 3D printing used during laparoscopic or robotic-assisted laparoscopic prostatectomy. Additional searches were conducted for articles that considered the role of artificial intelligence and machine learning and their application to robotic surgery. We excluded studies using intraoperative navigation technologies during open radical prostatectomy and studies considering technology to visualize lymph nodes. Intraoperative imaging using either transrectal ultrasonography or augmented reality was associated with a potential decrease in positive surgical margins rates. Improvements in detecting capsular involvement may be seen with augmented reality. The benefit, feasibility and applications of other imaging modalities such as 3D-printed models and optical imaging are discussed. The application of image-guided surgery and robotics has led to the development of promising new intraoperative imaging technologies such as augmented reality, fluorescence imaging, optical coherence tomography, confocal laser endomicroscopy and 3D printing. Currently challenges regarding tissue deformation and automatic tracking of prostate movements remain and there is a paucity in the literature supporting the use of these technologies. Urologic surgeons are encouraged to improve and test these advanced technologies in the clinical arena, preferably with comparative, randomized, trials.

Biofilm matrix and artificial mediator for efficient electron transport in CO2 microbial electrosynthesis

Microbial electrosynthesis (MES) has been highlighted as a means to valorize inorganic gaseous carbon, such as CO2, into value-added chemicals using electricity as the reducing power. Electrode-based electron transfer delivers respiratory electrons to a live-cell biocatalyst through a biofilm matrix or via electron shuttle molecules. The addition of artificial mediators, such as neutral red (NR) and 2-hydroxy-1,4-naphthoquinone (HNQ), increased acetate synthesis significantly, suggesting that these mediators improve the electron transport capability between the suspended cells and electrode. Regular media replacement also improves MES by adapting mediator-utilizing species in the reactor. MES without a mediator initially produced acetate at a reasonable rate (5.1 ± 0.2 mmol/l/day), but the rate became negligible in the later stage. In contrast, MES with NR or HNQ showed a higher acetate production rate (4.6 ± 0.4 vs. 7.4 ± 0.4 mmol/l/day, respectively) as the media replacement progressed. Confocal laser scanning microscopy and 3D imaging showed that the biofilm matrix consisted of live and dead cells, while the composition was different in the MES with and without a mediator. Microbial community analysis by next-generation sequencing (NGS) showed that acetogenic Acetobacterium (in suspension) and Sporomusa (in both suspension and biofilm) were dominant during the 96 days of operation. The biofilm and planktonic community interacted dynamically under MES conditions. This result provides a realistic model of biofilms and planktonic cells in the MES. The interaction of the suspended cells with the biofilm-forming electrode via electron shuttles could improve volumetric acetate production and stabilize the MES performance.

Fibrin Network Porosity and Endo-/Exogenous Thrombin Cross-talk.

The earliest assessment of fibrin network porosity used a liquid permeation system and confocal 3D microscopy, which was later replaced by scanning electron microscopy. Although the methods have extensively been applied in studies of health or disease, there remains debate on the choice of a proper clotting trigger. In this review, we assess published data and convey our opinions with regard to several issues. First, when the coagulation process is initiated by recombinant tissue factor (rTF) and phospholipids, the fibrin network porosity is regulated by the endogenous thrombin based on enzymatic activations of multiple coagulants. If purified thrombin (1.0 IU/mL) is employed as the clotting trigger, fibrin network porosity may be affected by exogenous thrombin, which directly polymerizes fibrinogen in plasma, and additionally by endogenous thrombin stemming from a "positive feedback loop" action of the added thrombin. Second, with use of either endogenous or exogenous thrombin, the concentration and clotting property of available fibrinogen both influence the fibrin network porosity. Third, in the assay systems in vitro, exogenous thrombin but not rTF-induced endogenous thrombin seems to be functional enough to activate factor XIII, which then contributes to a decrease in the fibrin network porosity. Fourth, fibrin network porosity determines the transport of fibrinolytic components into/through the clots and therefore serves as an indicator of the fibrinolysis potential in plasma.

The Efficient Improvement of Original Magnetite in Iron Ore Reduction Reaction in Magnetization Roasting Process and Mechanism Analysis by In Situ and Continuous Image Capture

Magnetization roasting followed by magnetic separation is considered an effective method for recovering iron minerals. As hematite and magnetite are the main concomitant constituents in iron ores, the separation index after the magnetization roasting will be more optimized than with only hematite. In this research, the mechanism of the original magnetite improving iron ore reduction during the magnetization roasting process was explored using ore fines and lump ore samples. Under optimum roasting conditions, the iron grade increased from 62.17% to 65.22%, and iron recovery increased from 84.02% to 92.02% after separation, when Fe in the original magnetite content increased from 0.31% to 8.09%, although the Fe masses in each sample were equal. For lump ores with magnetite and hematite intergrowth, the method of in situ and continuous image capture for microcrack generation and the evolution of the magnetization roasting process was innovatively examined with a laser scanning confocal microscope (LSCM) with confocal technology and 3D morphologic technology for the first time. The naturally uneven areas, protogenetic pore edges, and magnetite and hematite edges provided active sites for reduction reactions. The microcracks gradually evolved from the lump ore surface and the edges of magnetite and hematite, which had a direct connection with the efficient improvement in ore reduction.

Imaging of the internal chorion structure of rainbow trout Oncorhynchus mykiss live embryos and the distribution of quantum dots therein: Towards a deeper understanding of potential nanotoxicity

Quantum dots (QDs) are extensively explored in biomedicine but the understanding of the mechanism underlying the uptake of colloidal QDs by biological systems is still poor. The knowledge of their distribution in tissues and their possibilities to cross biological barriers, especially at early stages of organism development, is also still limited. The potential risk of nanoparticle exposure to aquatic organisms is continuously questioned in ecotoxicology. To answer this question, we investigated the interaction (penetration and distribution) of CdSe/ZnS-COOH QDs with the chorion as well as their toxicity, cytotoxicity and genotoxicity in “eye-egg” stage embryos of rainbow trout Oncorhynchus mykiss. Results of the confocal fluorescence microscopy, fluorescence spectroscopy and 3D image analysis of O. mykiss chorion showed that it consists of three different layers and has a hexagonal pattern of pores distribution. The present study has revealed that both the accumulation and the distribution of QDs within the chorion are related to its structure. QDs are accumulated in pore canals of the external membrane of a fertilized O. mykiss egg. Our study has shown that QDs exposure induces bradycardia in O. mykiss and, as a result, cardiac toxicity in embryos. However, embryo survival rates as well as cytotoxicity and genotoxicity effects in the fish exposed to QDs for 1 day were not found to differ significantly from those in 4-day exposed fish. Results of the mathematical modelling showed the adsorption of QDs aggregates on the outer surface of the chorion leading to the oxygen-deficient microenvironment in embryos. These results represent an important step forward towards a better understanding of the mechanisms underlying QDs impacts on living organisms, which is essential for clarifying the protective properties of biological structures, and is valuable for the evaluation of nanotoxicity to fish at early development stages.

Confocal microscopy 3D imaging of diesel particulate matter

To date, diesel particulate matter (DPM) has been described as aggregates of spherule particles with a smooth appearing surface. We have used a new colour confocal microscope imaging method to study the 3D shape of diesel particulate matter (DPM); we observed that the particles can have sharp jagged appearing edges and consistent with these findings, 2D light microscopy demonstrated that DPM adheres to human lung epithelial cells. Importantly, the slide preparation and confocal microscopy method applied avoids possible alteration to the particles’ surfaces and enables colour 3D visualisation of the particles. From twenty-one PM10 particles, the mean (standard deviation) major axis length was 5.6 (2.25) μm with corresponding values for the minor axis length of 3.8 (1.25) μm. These new findings may help explain why air pollution particulate matter (PM) has the ability to infiltrate human airway cells, potentially leading to respiratory tract, cardiovascular and neurological disease.

Microdesigned Nanocellulose-Based Flexible Antibacterial Aerogel Architectures Impregnated with Bioactive Cinnamomum cassia.

This work is strategically premeditated to study the potential of a herbal medicinal product as a natural bioactive ingredient to generate nanocellulose-based antibacterial architectures. In situ fibrillation of purified cellulose was done in cinnamon extract (ciE) to obtain microfibrillated cellulose (MFC). To this MFC suspension, carboxylated cellulose nanocrystals (cCNCs) were homogeneously mixed and the viscous gel thus obtained was freeze-dried to obtain lightweight and flexible composite aerogel architectures impregnated with ciE, namely, ciMFC/cCNCs. At an optimal concentration of 0.3 wt % cCNCs (i.e., for ciMFC/cCNCs_0.3), an improvement of around 106% in compressive strength and 175% increment in modulus were achieved as compared to pristine MFC architecture. The efficient loading and interaction of ciE components, specifically cinnamaldehyde, with MFC and cCNCs resulted in developing competent antibacterial surfaces with dense and uniform microstructures. Excellent and long-term antimicrobial activity of the optimized architectures (ciMFC/cCNCs_0.3) was confirmed through various antibacterial assays like the zone inhibition method, bacterial growth observation at OD600, minimum inhibitory concentration (MIC, here 1 mg/mL), minimum bactericidal concentration (MBC, here 3-5 mg/mL), and Live/Dead BacLight viability tests. The changes in the bacterial morphology with a disrupted membrane were further confirmed through various imaging techniques like confocal laser scanning microscopy, FESEM, AFM, and 3D digital microscopy. The dry composite architecture showed the persuasive capability of suppressing the growth of airborne bacteria, which in combination with antibacterial efficiency in the wet state is considered as an imperative aspect for a material to act as the novel biomaterial. Furthermore, these architectures demonstrated excellent antibacterial performance under real "in use" contamination prone conditions. Hence, this work provides avenues for the application of crude natural extracts in developing novel forms of advanced functional biomaterials that can be used for assorted biological/healthcare applications such as wound care and antimicrobial filtering units.

Fiber-coupled Chromatic Confocal 3D Measurement System and Comparative Study of Spectral Data Processing Algorithms

Fiber-coupled Chromatic Confocal 3D Measurement System and Comparative Study of Spectral Data Processing Algorithms

Real-Time Ratiometric Imaging of Micelles Assembly State in a Microfluidic Cancer-on-a-Chip.

The performance of supramolecular nanocarriers as drug delivery systems depends on their stability in the complex and dynamic biological media. After administration, nanocarriers are challenged by physiological barriers such as shear stress and proteins present in blood, endothelial wall, extracellular matrix, and eventually cancer cell membrane. While early disassembly will result in a premature drug release, extreme stability of the nanocarriers can lead to poor drug release and low efficiency. Therefore, comprehensive understanding of the stability and assembly state of supramolecular carriers in each stage of delivery is the key factor for the rational design of these systems. One of the main challenges is that current 2D in vitro models do not provide exhaustive information, as they fail to recapitulate the 3D tumor microenvironment. This deficiency in the 2D model complexity is the main reason for the differences observed in vivo when testing the performance of supramolecular nanocarriers. Herein, we present a real-time monitoring study of self-assembled micelles stability and extravasation, combining spectral confocal microscopy and a microfluidic cancer-on-a-chip. The combination of advanced imaging and a reliable 3D model allows tracking of micelle disassembly by following the spectral properties of the amphiphiles in space and time during the crucial steps of drug delivery. The spectrally active micelles were introduced under flow and their position and conformation continuously followed by spectral imaging during the crossing of barriers, revealing the interplay between carrier structure, micellar stability, and extravasation. Integrating the ability of the micelles to change their fluorescent properties when disassembled, spectral confocal imaging and 3D microfluidic tumor blood vessel-on-a-chip resulted in the establishment of a robust testing platform suitable for real-time imaging and evaluation of supramolecular drug delivery carrier’s stability.

Thrombospondin 1‐induced exosomal proteins attenuate hypoxia‐induced paraptosis in corneal epithelial cells and promote wound healing

Thrombospondin-1 (TSP1) is involved in corneal wound healing caused by chemical injury. Herein, we examined the effects of TSP1 on hypoxia-induced damages and wound-healing activity in human corneal epithelial (HCE) cells. Exosomal protein expression was determined using liquid chromatography-tandem mass spectrometry, and HCE cell migration and motility were examined through wound-healing assay and time-lapse microscopy. Reestablishment of cell junctions by TSP1 was assessed through confocal microscopy and 3D image reconstruction. Our results show that CoCl2 -induced hypoxia promoted HCE cell death by paraptosis. TSP1 protected these cells against paraptosis by attenuating mitochondrial membrane potential depletion, swelling and dilation of endoplasmic reticulum and mitochondria, and mitochondrial fission. Exosomes isolated from HCE cells treated with TSP1 contained wound healing-associated proteins that were taken up by HCE cells to promote tissue remodeling and repair. TSP1 protected HCE cells against hypoxia-induced damages and inhibited paraptosis progression by promoting cell migration, cell-cell adhesion, and extracellular matrix remodeling. These findings indicate that TSP1 ameliorates hypoxia-induced paraptosis in HCE cells and promotes wound healing and remodeling by regulating exosomal protein expression. TSP1 may, therefore, play important roles in the treatment of hypoxia-associated corneal diseases.

Dendritic Spine Remodeling and Synaptic Tau Levels in PS19 Tauopathy Mice

Synapse or dendritic spine loss is the strongest correlate of cognitive decline in Alzheimer’s disease (AD), and neurofibrillary tangles (NFTs), but not amyloid-β plaques, associate more closely with transition to mild cognitive impairment. Yet, how dendritic spine architecture is affected by hyperphosphorylated tau is still an ongoing question. To address this, we combined cell and biochemical analyses of the Tau P301S mouse line (PS19). Individual pyramidal neurons in the hippocampus and medial prefrontal cortex (mPFC) were targeted for iontophoretic microinjection of fluorescent dye, followed by high-resolution confocal microscopy and 3D morphometry analysis. In the hippocampus, PS19 mice and non-transgenic (NTG) littermates displayed equivalent spine density at 6 and 9 months, but both genotypes exhibited age-related thin spine loss. PS19 mice exhibited significant increases in synaptic tau protein levels and mean dendritic spine head diameter with age. This suggests that CA1 pyramidal neurons in PS19 mice may undergo spine remodeling in response to tau accumulation and age. In the mPFC, spine density was similar among PS19 mice and NTG littermates at 6 and 9 months, but age-related reductions in synaptic tau levels were observed among PS19 mice. Collectively, these studies reveal brain region-specific changes in dendritic spine density and morphology in response to age and the presence of hyperphosphorylated tau in the PS19 mouse line.

A method for the taphonomic assessment of bone tools using 3D surface texture analysis of bone microtopography

Increasingly researchers have employed confocal microscopy and 3D surface texture analysis to assess bone surface modifications in an effort to understand ancient behavior. However, quantitative comparisons between the surfaces of purported archaeological bone tools and experimentally manufactured and used bones are complicated by taphonomic processes affecting ancient bone. Nonetheless, it may be reasonable to assume that bones within the same deposits are altered similarly and thus these alterations are quantifiable. Here we show how unworked bones can be used to quantify the taphonomic effect on bone surfaces and how this effect can then be controlled for and incorporated into an analysis for evaluating the modified surfaces of purported bone tools. To assess the baseline taphonomy of Middle Paleolithic archaeological deposits associated with typologically identified bone artifacts, specifically lissoirs, we directly compare the surface textures of ancient and modern unworked ribs. We then compare the ancient unworked ribs and lissoirs to assess their differences and predict the ancient artifacts’ original surface state using a multilevel multivariate Bayesian model. Our findings demonstrate that three of five tested surface texture parameters (Sa, Spc, and IsT) are useful for distinguishing surface type. Our model predictions show that lissoirs tend to be less rough, have more rounded surface peaks, and exhibit more directionally oriented surfaces. These characteristics are likely due to anthropogenic modifications and would have been more pronounced at deposition. Quantifying taphonomic alterations moves us one step closer to accurately assessing how bone artifacts were made and used in the ancient past.

Effect of fluorescence labeling on mechanical properties of silica filled silicone rubber

The Silica filler has been successfully fluorescently labeled by bifunctional silane coupling agent and europium nitrate through chemical grafting method. The thermal weight loss of the labeled silica at 200 °C was 1.75%, which was lower than 3.57% before labeling. This indicated that the labeled material had good thermal stability below 200 °C, and the water content of the labeled filler decreased due to its reduced hydrophilicity on the surface of the filler. Polysiloxane was filled with labeled or unlabeled silica which had different filler loading levels (from 10 phr to 60 phr) by diluted mixing on the purpose of investigating effect of fluorescent labeling on the mechanical property of rubber composite. According to the results of laser confocal microscope 3D imaging and software calculation, the network connection rate increased from 23% to 60% with the increase of filling amount. When the filling contents are more than 40%, the mechanical properties of unlabeled silica filled silicone rubber decrease slightly, while the mechanical properties of labeled silica filled silicone rubber almost remain unchanged, which is related to the increase interaction of filler and matrix through organic functionalization on the surface of the latter. However, the influence trend of fillers on mechanical properties of the two systems is basically the same. Fluorescent labeled silica is expected to be an effective tool for the correlation between microstructure and mechanical properties.

Confocal laser scanning and 3D reconstruction methods for the subsurface damage of polished optics

The subsurface damage (SSD) of optics is one of the key factors limiting the increase of energy density of high-power solid-state lasers. Because of the characteristics of small size, low density and wide distribution, it is difficult to detect the SSD of large polished optics with high-accuracy. Confocal laser scanning and three-dimensional (3D) reconstruction methods are proposed in this paper. 3D scanning in a small area is realized by a galvo and piezo stage, and sub-aperture scanning in a large area is realized by a XY stage. Sub-aperture images are stitched together to construct a volume data field, and then a modified Marching Cubes (MC) algorithm is used for 3D reconstruction. Simulations and experimental results show that the algorithm runs faster with low memory footprint, and morphologies of SSDs are displayed intuitively and accurately. The proposed methods provide quantitative evaluations such as the positions, depths and cross-sectional areas of SSDs.

The discovery of Caligus quadratus Shiino, 1954 (Copepoda: Caligidae) in the Mediterranean Sea, with a new host record and supplementary morphological information obtained using confocal laser scanning microscope (CLSM) and 3D image processing.

In this study, supplementary information on the morphology of the siphonostomatoid copepod Caligus quadratus Shiino, 1954 (Copepoda: Caligidae) is given based on the new material collected from the gills of the Atlantic bluefin tuna, Thunnus thynnus (Linnaeus, 1758) caught in the Gulf of Antalya, Turkey. The morphology of C. quadratus is re-examined for the first time by adopting a recently developed visualisation technique by Kamanli et al. [1]. Appendages of Congo red stained specimens of C. quadratus were dissected and scanned using confocal laser scanning microscope (CLSM) and the CLSM images were processed using Dristhi software programme. 3D reconstructions of some confusing appendages were visualised using Drishti. Line drawing was used to depict the habitus of both female and male C. quadratus. Key diagnostic characters of C. quadratus are presented together with the newly observed additional taxonomic characters. In addition, previously misinterpreted and simply overlooked features in the previous descriptions of C. quadratus are also re-described. This is the first report of C. quadratus from the Mediterranean Sea and the Atlantic bluefin tuna constitutes a new host record for this caligid copepod.

Friction coefficient study of nanocomposite Al2O3–NbC obtained by spark plasma sintering-SPS

PurposeThis study aims to investigate the friction coefficient of Al2O3–NbC nanocomposite obtained by spark plasma sintering sliding against a steel ball.Design/methodology/approachTribological tests were carried out using a reciprocating nanotribometer in a ball on flat configuration with normal loads in the range from 10 to 100 mN under dry conditions. Surface changes were analyzed by confocal microscopy and 3D profilometry.FindingsThe values of the friction coefficient varied from 0.15 to 0.6 and are independent of the applied load.Originality/valueThe tribological behavior is attributed to fracture in the contact region and the effect of wear debris.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2019-0356/

Chronic intermittent ethanol and lipopolysaccharide exposure differentially alter Iba1-derived microglia morphology in the prelimbic cortex and nucleus accumbens core of male Long-Evans rats.

Accumulating evidence has linked pathological changes associated with chronic alcohol exposure to neuroimmune signaling mediated by microglia. Prior characterization of the microglial structure-function relationship demonstrates that alterations in activity states occur concomitantly with reorganization of cellular architecture. Accordingly, gaining a better understanding of microglial morphological changes associated with ethanol exposure will provide valuable insight into how neuroimmune signaling may contribute to ethanol-induced reshaping of neuronal function. Here we have used Iba1-staining combined with high-resolution confocal imaging and 3D reconstruction to examine microglial structure in the prelimbic (PL) cortex and nucleus accumbens (NAc) in male Long-Evans rats. Rats were either sacrificed at peak withdrawal following 15days of exposure to chronic intermittent ethanol (CIE) or 24hr after two consecutive injections of the immune activator lipopolysaccharide (LPS), each separated by 24hr. LPS exposure resulted in dramatic structural reorganization of microglia in the PL cortex, including increased soma volume, overall cellular volume, and branching complexity. In comparison, CIE exposure was associated with a subtle increase in somatic volume and differential effects on microglia processes, which were largely absent in the NAc. These data reveal that microglial activation following a neuroimmune challenge with LPS or exposure to chronic alcohol exhibits distinct morphometric profiles and brain region-dependent specificity.

Size-dependent cellular internalization and effects of polystyrene microplastics in microalgae P. helgolandica var. tsingtaoensis and S. quadricauda

Microplastics (MPs) are persistent contaminants in aquatic environments. Microalgae, as the main phytoplankton and primary producers, usually co-exist with MPs. Despite previous studies that have proved the interaction of MPs and microalgae, it is largely unknown whether MPs can be uptake into cells of microalgae. In this study, both marine P. helgolandica var. tsingtaoensis and freshwater microalgae S. quadricauda were respectively exposed to 10 mg/L polystyrene microbeads with five diameter sizes: 1.0, 2.0, 3.0, 4.0, and 5.0 μm. Confocal laser scanning and 3D image analysis showed that mean 24.0 % or 11.3 % cells of P. helgolandica var. tsingtaoensis contained 1.0 μm or 2.0 μm MPs after 72 h exposure. While mean 43.3 % or 15.3 % of S. quadricauda individuals engulfed 1.0 μm or 2.0 μm MPs within cells. But, none of 3.0–5.0 μm MPs were observed within algal cells. These results demonstrate the size-dependent cellular internalization of MPs in microalgae. Exposure to 1.0–2.0 μm PS MPs caused a significant reduction in the density of microalgae and influenced photosynthesis, which suggests cellular internalization of MPs can influence algal fertility and growth. This discovery first confirms cellular internalization of MPs in phytoplankton, of significance for the fate and eco-toxicity of MPs in the aquatic ecosystem.