Coastal Mussel (Mytilus spp.) Soft Tissues as Bioindicators of Methylmercury: Exploring the Relationship Between Condition Index and Methylmercury Concentrations.

We investigated total mercury (THg) and methylmercury (MeHg) concentrations in coastal mussels (Mytilus spp.) sampled from the Minas Basin, Bay of Fundy and evaluated the relationship with condition index (CI). THg concentrations were low in sediment (mean THg = 5.15 ± 2.11 ng/g dw; n = 6) and soft tissues (mean THg = 62.3 ± 13.7 ng/g; mean MeHg = 13.2 ± 6.3 ng/g; n = 57). The THg in tissues had no significant relationship with CI (Rs= -0.205, p = 0.126). MeHg in tissues were significantly and negatively correlated with condition index (Rs = -0.361, p = 0.006) indicating that healthier mussels (higher CI) have lower mercury content possibly due to elimination strategies or growth dilution.

Mosses as bioindicators of air pollution with potentially toxic elements in the Burabay State National Natural Park, Kazakhstan.

The Burabay State National Natural Park is a national park of the great natural and historical values located in the north of Kazakhstan, which has been exposed in recent years to significant anthropogenic impact. The moss biomonitoring was performed in the Borovoye resort community, an important tourist destination in the national park, to identify the level of air pollution. Mosses collected at 29 locations were subjected to neutron activation analysis to determine 36 elements and additionally to ICP-OES to detect the level of Cu and Pb. Factor analysis was applied to check if there are any associations between identified elements and to link them with possible emission sources. According to contamination factor and pollution load indices the investigated area belongs to three classes of pollution: unpolluted, suspected and moderate. Potential ecological risk index calculated for selected elements revealed harmless risk to human health. The level of element obtained in Burabay State National Natural Park was compared with the data available for other national parks.

High toxicity of agro-industrial wastewater on aquatic fauna of a South American stream: Mortality of aquatic turtles and amphibian tadpoles as bioindicators of environmental health.

The aim of this study was to characterize an aquatic system of Santa Fe province (Argentina) receiving wastewater from agro-industrial activities (mainly dairy) by in situ assessment (fauna mortality, physicochemical, microbiological, and pesticide residues measurement), and ecotoxicity bioassays on amphibian tadpoles. Water and sediment samples were obtained from the Los Troncos Stream (LTS), previous to the confluence with the "San Carlos" drainage channel (SCC), and from the SCC. Biological parameters (mortality and sublethal biomarkers) were used to evaluate ecotoxicity during 10-day exposure of Rhinella arenarum tadpoles to LTS and SCC samples. Nine pesticides were detected in both LTS and SCC. Chemical and biochemical oxygen demand, ammonia, and coliform count recorded in SCC greatly exceeded limits for aquatic life protection. At SCC and LTS after the confluence with SCC, numerous dying and dead aquatic turtles (Phrynops hilarii) were recorded. In the ecotoxicity assessment, no mortality of tadpoles was observed in LTS treatment, whereas total mortality (100%) was observed in SCC treatments in dilution higher than 50% of water and sediment. For SCC, median lethal concentration and the 95% confidence limits was 18.30% (14.71-22.77) at 24 h; lowest-observed and no-observed effect concentrations were 12.5% and 6.25%, respectively. Oxidative stress and neurotoxicity were observed in tadpoles exposed to 25% SCC dilution treatment. In addition, there was a large genotoxic effect (micronuclei test) in all sublethal SCC dilution treatments (6.25%, 12.5%, and 25%). These results alert about the high environmental quality deterioration and high ecotoxicity for aquatic fauna of aquatic ecosystems affected by agro-industrial wastewater. PRACTITIONER POINTS: Great mortality of turtles was observed in a basin with a high load of agro-industrial wastewater. San Carlos Channel (SCC), where effluents are spilled, is environmentally deteriorated. The water-sediment matrix of SCC caused 100% lethality in tadpoles. SCC dilutions caused neurotoxicity, oxidative stress, and genotoxicity on tadpoles.

Birds as bioindicators of plastic pollution in terrestrial and freshwater environments: A 30-year review.

Plastic pollution is a global concern that has grown ever more acute in recent years. Most research has focused on the impact of plastic pollution in marine environments. However, plastic is increasingly being detected in terrestrial and freshwater environments with key inland sources including landfills, where it is accessible to a wide range of organisms. Birds are effective bioindicators of pollutants for many reasons, including their high mobility and high intra- and interspecific variation in trophic levels. Freshwater and terrestrial bird species are under-represented in plastic pollution research compared to marine species. We reviewed 106 studies (spanning from 1994 onwards) that have detected plastics in bird species dwelling in freshwater and/or terrestrial habitats, identifying knowledge gaps. Seventy-two studies focused solely on macroplastics (fragments >5 mm), compared to 22 microplastic (fragments <5 mm) studies. A further 12 studies identified plastics as both microplastics and macroplastics. No study investigated nanoplastic (particles <100 nm) exposure. Research to date has geographical and species' biases while ignoring nanoplastic sequestration in free-living freshwater, terrestrial and marine bird species. Building on the baseline search presented here, we urge researchers to develop and validate standardised field sampling techniques and laboratory analytical protocols such as Raman spectroscopy to allow for the quantification and identification of micro- and nanoplastics in terrestrial and freshwater environments and the species therein. Future studies should consistently report the internalised and background concentrations, types, sizes and forms of plastics. This will enable a better understanding of the sources of plastic pollution and their routes of exposure to birds of terrestrial and freshwater environments, providing a more comprehensive insight into the potential impacts on birds.

Phytoplankton species composition as bioindicator in the largest fragmented channel of the Pearl River, China.

To test the serial discontinuity concept (SDC) predictions in a regulated river ecosystem, environmental parameters and phytoplankton community structure were determined in a subtropical river (China) which was regulated by 11 cascade dams. Our results showed that total phosphorus (TP) and silicate during the wet period in several dams supported the SDC predictions. Variations of phytoplankton species composition in several cascade dams, such as Datengxia (DTX) and Changzhou (CZ), also supported the SDC predictions. Moreover, the stations near the dams showed the maximum or minimum values of total species numbers in each cascade segment. Predictive model indicated that the types of phytoplankton decreased in the middle reaches, conforming to SDC predictions. In the whole system of cascading dams, an increase in silicate concentration and phytoplankton communities in the downstream was also consistent with SDC predictions. Therefore, these findings aligned with the SDC predictions in the aspects of both single dam and whole cascade dam system to some extent. In future research, our aim is to further investigate the effects of cascade damming on additional phytoplankton-related indices in this aquatic ecosystem. We hope to gather more comprehensive data to fully validate the SDC predictions.

Bioindicator responses to extreme conditions: Insights into pH and bioavailable metals under acidic metal environments.

Acid mine drainage (AMD) caused environmental risks from heavy metal pollution, requiring treatment methods such as chemical precipitation and biological treatment. Monitoring and adapting treatment processes was crucial for success, but cost-effective pollution monitoring methods were lacking. Using bioindicators measured through 16S rRNA was a promising method to assess environmental pollution. This study evaluated the effects of AMD on ecological health using the ecological risk index (RI) and the Risk Assessment Code (RAC) indices. Additionally, we also examined how acidic metal stress affected the diversity of bacteria and fungi, as well as their networks. Bioindicators were identified using linear discriminant analysis effect size (LEfSe), Partial least squares regression (PLS-R), and Spearman analyses. The study found that Cd, Cu, Pb, and As pose potential ecological risks in that order. Fungal diversity decreased by 44.88% in AMD-affected areas, more than the 33.61% decrease in bacterial diversity. Microbial diversity was positively correlated with pH (r = 0.88, p = 0.04) and negatively correlated with bioavailable metal concentrations (r = -0.59, p = 0.05). Similarly, microbial diversity was negatively correlated with bioavailable metal concentrations (bio_Cu, bio_Pb, bio_Cd) (r = 0.79, p = 0.03). Acidiferrobacter and Thermoplasmataceae were prevalent in acidic metal environments, while Puia and Chitinophagaceae were identified as biomarker species in the control area (LDA>4). Acidiferrobacter and Thermoplasmataceae were found to be pH-tolerant bioindicators with high reliability (r = 1, P < 0.05, BW > 0.1) through PLS-R and Spearman analysis. Conversely, Puia and Chitinophagaceae were pH-sensitive bioindicators, while Teratosphaeriaceae was a potential bioindicator for Cu-Zn-Cd metal pollution. This study identified bioindicator species for acid and metal pollution in AMD habitats. This study outlined the focus of biological monitoring in AMD acidic stress environments, including extreme pH, heavy metal pollutants, and indicator species. It also provided essential information for heavy metal bioremediation, such as the role of omics and the effects of organic matter on metal bioavailability.

Effects of pasture intensification and sugarcane cultivation on non-target species: A realistic evaluation in pesticide-contaminated mesocosms.

Conventional soil management in agricultural areas may expose non-target organisms living nearby to several types of contaminants. In this study, the effects of soil management in extensive pasture (EP), intensive pasture (IP), and sugarcane crops (C) were evaluated in a realistic-field-scale study. Thirteen aquatic mesocosms embedded in EP, IP, and C treatments were monitored over 392 days. The recommended management for each of the areas was simulated, such as tillage, fertilizer, pesticides (i.e. 2,4-D, fipronil) and vinasse application, and cattle pasture. To access the potential toxic effects that the different steps of soil management in these areas may cause, the cladoceran Ceriophania silvestrii was used as aquatic bioindicator, the dicot Eruca sativa as phytotoxicity bioindicator in water, and the dipteran Chironomus sancticaroli as sediment bioindicator. Generalized linear mixed models were used to identify differences between the treatments. Low concentrations of 2,4-D (<97 µg L-1) and fipronil (<0.21 µg L-1) in water were able to alter fecundity, female survival, and the intrinsic rate of population increase of C. silvestrii in IP and C treatments. Similarly, the dicot E. sativa had germination, shoot and root growth affected mainly by 2,4-D concentrations in the water. For C. sancticarolli, larval development was affected by the presence of fipronil (<402.6 ng g-1). The acidic pH (below 5) reduced the fecundity and female survival of C. silvestrii and affected the germination and growth of E. sativa. Fecundity and female survival of C. silvestrii decrease in the presence of phosphorus-containing elements. The outcomes of this study may improve our understanding of the consequences of exposure of freshwater biota to complex stressors in an environment that is rapidly and constantly changing.

Function rather than structure of phytoplankton community reveals changes of water quality in an ecological restored lake.

Although phytoplankton is well known as robust bioindicators to aquatic environments, their indicating functions based on different community parameters remain to be understood. In order to filter effective bioindicators in aquatic ecosystems, four phytoplankton community parameters including species richness (SR), total biomass (SBP), functional groups (FGBP), and size-fractionated chlorophyll-a (SC) were demonstrated in a subtropical artificial lake with ecological restoration in South China. Our results indicated that all the above four parameters exhibited high sensitivity to environmental variations and illustrated distinct aspects of indicating functions to aquatic environments due to their individual biological characteristics. Based on FGBP, both spatial and temporal differences in phytoplankton community could be identified. SR and SBP only classified the spatial and temporal distributions, respectively, while SC could distinguish the sewage outfalls from other sites. In terms of ecological management, two parameters (SR and FGBP) could distinguish the restored waters from untreated environments as non-point source pollution, and another parameter SC could indicate the sewage outfalls as point source pollution. Therefore, the combination of the above two categories of phytoplankton community parameters could make the strongest indicating functions. Our study provided greater insight into indicating functions of phytoplankton community parameters in an ecological restored lake and enabled better managements in such artificial lakes.

Biomonitoring tool for New Zealand peatlands: Testate amoebae and vascular plants as promising bioindicators.

In the last two centuries, a high proportion of peatlands have been lost or severely degraded across the world. The value of peatlands is now well-recognised for biodiversity conservation, flood management, and carbon mitigation, with peatland restoration now central to many government policies for climate action. A challenge, however, is to determine 'natural' and 'disturbed' conditions of peatlands to establish realistic baselines for assessing degradation and setting restoration targets. This requires a tool or set of tools that can rapidly and reliably capture peatland condition across space and time. Our aim was to develop such a tool based on combined analysis of plant and testate amoebae; a group of shelled protists commonly used as indicators of ecological change in peatlands. The value of testate amoebae is well established in Northern Hemisphere Sphagnum-dominated peatlands; however, relatively little work has been undertaken for Southern Hemisphere peat forming systems. Here we provide the first assessment and comparison of the bioindicator value of testate amoebae and vascular plants in the context of Southern Hemisphere peatlands. Our results further demonstrate the unique ecohydrological dynamics at play in New Zealand peat forming systems that set them apart from Northern Hemisphere peatlands. Our results show that plant and testate amoeba communities provided valuable information on peatland condition at different scales, we found that testate amoebae tracked changes in the abiotic variables (depth to water table, pH, and conductivity) more closely than vascular plants. Our results further demonstrate that functional traits of testate amoebae showed promising relationships with disturbance. Amoeba test compression, aperture position and test size were linked to changes in hydrology driven by fluctuations in ground water tables; however, trait responses manifested differently in ombrotrophic and minerotrophic peatlands. Overall, testate amoebae provide a promising bioindicator for tracking degradation in New Zealand peatlands and a potential additional tool to assess peatland condition.

Fungal communities as dual indicators of river biodiversity and water quality assessment.

Given their ecological importance, bioindicators are used for the assessment of the health of river ecosystems. This study explored the fungal compositions and the potential of fungal taxa as bioindicators for indicating the water quality of the Mekong River, as the use of fungal indicators of the Mekong River was not previously well characterized. The Mekong River exhibited dynamic variations in both physicochemical/hydrochemical properties and fungal communities according to seasons and locations. The results revealed the dominance of alkaline earth metal ions and weak acids in the water. The magnesium-bicarbonate water type was found in the dry season, but the water became the chloride-calcium type or mixed type of magnesium-bicarbonate and chloride-calcium in the rainy season at downstream sites. Fungal composition analysis revealed the dominance of Chytridiomycota in the dry season and intermediate periods, and Ascomycota and Basidiomycota in the rainy season. The fungal communities were influenced by stochastic and deterministic assembly processes, mainly homogeneous selection, heterogeneous selection, and dispersal limitation. The extent of environmental filtering implied that some fungal taxa were affected by environmental conditions, suggesting the possibility of identifying certain fungal taxa suitable for being bioindicators of water quality. Subsequently, machine learning with recursive feature elimination identified specific fungal bins mostly consisting of Agaricomycetes (mainly Polyporales, Agaricales, and Auriculariales), Dothideomycetes (mainly Pleosporales), Saccharomycetes (mainly Saccharomycetales), Chytridiomycota, and Rozellomycota as bioindicators that could predict ambient and irrigation water quality with high selectivity and sensitivity. These results thus promote the use of fungal indicators to assess the health of the river.

Predictive statistical models for monitoring antimicrobial resistance spread in the environment using Apis mellifera (L. 1758) colonies.

The rise of antimicrobial resistance (AMR) is one of the most relevant problems for human and animal health. According to One Health Approach, it is important to regulate the use of antimicrobials and monitor the spread of AMR in the environment as well. Apis mellifera (L. 1758) colonies were used as bioindicators thanks to their physical and behavioural characteristics. During their foraging flights, bees can intercept small particles, including atmospheric particulate matter, etc., and also microorganisms. To date, the antimicrobial surveillance network is limited to the sanitary level but lacks into environmental context. This study aimed to evaluate the use of A. mellifera colonies distributed throughout the Emilia-Romagna region (Italy) as indicators of environmental antimicrobial-resistant bacteria. This was performed by creating a statistical predictive model that establishes correlations between environmental characteristics and the likelihood of isolating specific bacterial genera and antimicrobial-resistant strains. A total of 608 strains were isolated and tested for susceptibility to 19 different antimicrobials. Aztreonam-resistant strains were significantly related to environments with sanitary structures, agricultural areas and wetlands, while urban areas present a higher probability of trimethoprim/sulfamethoxazole-resistant strains isolation. Concerning genera, environments with sanitary structures and wetlands are significantly related to the genera Proteus spp., while the Escherichia spp. strains can be probably isolated in industrial environments. The obtained models showed maximum values of Models Accuracy and robustness (R2) of 55 % and 24 %, respectively. The results indicate the efficacy of utilizing A. mellifera colonies as valuable bioindicators for estimating the prevalence of AMR in environmentally disseminated bacteria. This survey can be considered a good basis for the development of further studies focused on monitoring both sanitary and animal pathology, creating a specific network in the environments of interest.

Fluorine mass balance analysis in wild boar organs from the Bohemian Forest National Park.

Wild boars have been reported as bioindicators for per- and polyfluoroalkyl substances (PFAS) in a variety of studies. However, data about PFAS levels in wild boars from sites with limited industrial and general human activity is scarce. In this study, wild boar (Sus scrofa) organs from the Bohemian Forest National Park (Czech Republic) were used as bioindicators for PFAS pollution. In this work, 29 livers and 24 kidneys from 30 wild boars (0.5-5 years) were investigated using a fluorine mass balance approach. For this, the samples were measured using high performance liquid chromatography with electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS), targeting 30 PFAS, including legacy and replacement PFAS, direct total oxidisable precursor assay (dTOPA) and combustion ion chromatography (CIC). Perfluorocarboxylic acids (PFCAs) from C7 to C14 and perfluorooctanesulfonic acid (PFOS) were detected in >50 % of samples. In the livers, PFCAs dominated the profile with median concentrations of 230 µg/kg for perfluorononanoic acid (PFNA) and 75 µg/kg perfluorooctanoic acid (PFOA). PFOA and PFNA concentrations in the livers were one order of magnitude higher than in livers from wild boars caught in rural NE Germany considered as background concentration. PFOS in liver contributed only 30 % to the Σc(PFASTarget) with a median concentration of 170 µg/kg. Kidneys and livers contain an average of 2460 µg F/kg and 6800 µg F/kg extractable organic fluorine (EOF) respectively. Σc(PFASTarget) add up to a maximum of 10 % of the extractable organic fluorine. After oxidisation of the samples, PFOA, PFNA and Σc(PFASdTOPA) increased in livers, but could not explain the EOF. The elevated concentration of PFOA and PFNA may indicate differences in biomagnification for different habitats or an unidentified PFAS source in proximity to the national park.

Luminescent Bacteria as Bioindicators in Screening and Selection of Enzymes Detoxifying Various Mycotoxins.

Interest in enzymes capable of neutralizing various mycotoxins is quite high. The methods used for the screening and selection of enzymes that catalyze the detoxification of mycotoxins should be sensitive and fast. However toxic compounds can be generated under the action of such enzymes. Thus, the assessment of the overall reduction in the toxic properties of reaction media towards bioluminescent bacteria seems to be the most reasonable control method allowing a quick search for the effective enzymatic biocatalysts. The influence of a wide range of mycotoxins and glucanases, which hydrolyze toxins with different chemical structures, on the analytical characteristics of luminescent photobacteria as a biosensing element has been studied. Different glucanases (ß-glucosidase and endoglucanase) were initially selected for reactions with 10 mycotoxins based on the results of molecular docking which was performed in silico with 20 mycotoxins. Finally, the biorecognizing luminescent cells were used to estimate the residual toxicity of reaction media with mycotoxins after their interaction with enzymes. The notable non-catalytic decrease in toxicity of media containing deoxynivalenol was revealed with luminous cells for both types of tested glucanases, whereas ß-glucosidase provided a significant catalytic detoxification of media with aflatoxin B2 and zearalenone at pH 6.0.

Trophic assessment of red seabream (Pagrus major) as a possible bioindicator of human activities in the South Sea of Korea using stable C and N isotopes.

To assess the impact of sand mining on resource utilization by the red seabream (Pagrus major) and the trophic structure of fish assemblages two years after mining activities, we compared stable isotope ratios (δ13C and δ15N) and isotopic niches between aggregated mining and control sites in April and August 2022. Our results showed no spatial differences in the δ13C and δ15N values of red seabream between the sand mining and control sites, suggesting that the mining did not affect their dietary resources. Furthermore, the considerable overlap among fish consumers suggested that the fish food web in mining areas has trophic functions similar to those in natural habitats after mining activities. Overall, our study enhances our understanding of ecosystem conservation and the ecological-based management of coastal areas.

Traditional potato tillage systems in the Peruvian Andes impact bacterial diversity, evenness, community composition, and functions in soil microbiomes.

The soil microbiome, a crucial component of agricultural ecosystems, plays a pivotal role in crop production and ecosystem functioning. However, its response to traditional tillage systems in potato cultivation in the Peruvian highlands is still far from understood. Here, ecological and functional aspects of the bacterial community were analyzed based on soil samples from two traditional tillage systems: 'chiwa' (minimal tillage) and 'barbecho' (full tillage), in the Huanuco region of the Peruvian central Andes. Similar soil bacterial community composition was shown for minimal tillage system, but it was heterogeneous for full tillage system. This soil bacterial community composition under full tillage system may be attributed to stochastic, and a more dynamic environment within this tillage system. 'Chiwa' and 'barbecho' soils harbored distinct bacterial genera into their communities, indicating their potential as bioindicators of traditional tillage effects. Functional analysis revealed common metabolic pathways in both tillage systems, with differences in anaerobic pathways in 'chiwa' and more diverse pathways in 'barbecho'. These findings open the possibilities to explore microbial bioindicators for minimal and full tillage systems, which are in relationship with healthy soil, and they can be used to propose adequate tillage systems for the sowing of potatoes in Peru.

Pine needles as bioindicator and biomagnetic indicator of selected metals in the street dust, a case study from southeastern Iran.

Among the different approaches currently being used to evaluate the contamination level of street dust, the magnetic susceptibility of dust and urban tree leaves has received little attention. The key objectives of this study were: (i) to investigate the feasibility of using pine needles as a bioindicator and biomagnetic indicator for estimating the concentration of selected metals in street dust, and (ii) to predict the contamination level of street dust by selected metals using magnetic susceptibility. Street dust and pine tree needle samples were taken from 60 locations in three adjacent cities in Kerman province (Kerman, Rafsanjan, and Sirjan), southeastern Iran. The total concentrations of selected metals, including Cu, Zn, Fe, Mn, Ni, and Pb, and the magnetic susceptibility (χlf and χhf) values of both pine tree needles and street dust samples were determined. Among the three cities studied, samples from Kerman showed the highest magnetic susceptibility and metal concentration values. This could be attributed to the larger size and much higher population density of this city, with more industrial activities and urban traffic than the other two cities investigated. The results also showed that the concentrations of metals in pine needles were strongly correlated (p < 0.01) with those in street dust. The magnetic susceptibility of pine needles and the concentrations of Fe, Pb, Zn, Cu, Ni, and Mn in street dust showed a statistically significant correlation (p < 0.01). A strong and statistically significant correlation (p < 0.01) was also found between magnetic susceptibility and the concentration of metals in pine needles. In conclusion, strong relationships between magnetic properties and metal concentrations of pine needles with those of street dust samples seem to make pine needles a good bioindicator and biomagnetic estimator of the contamination level of metals in street dust.

Young-of-the-year fish as bioindicators of eutrophication and temperature regime of water bodies.

Young-of-the-year fish communities are widely used as bioindicators of various environmental disturbances. This study was conducted from 1997 to 2015 and aims to develop fish trait-based indices of changes in the temperature regime and eutrophication of water bodies in the Dnipro River basin. We identified fish traits that significantly correlate with both temperature and chlorophyll-a concentration optimum: reproduction habitat, oxygen tolerance, and toxicity tolerance. Compared to other ecological groups, lithophilic species exhibited the lowest degree of thermal and eutrophication optimum, indicating this species' greater vulnerability to environmental alteration. Fish species that are intolerant to water quality and low oxygen concentration were the most sensitive to changes in temperature regime and eutrophication level. Salinity preferences and water quality tolerance emerged as reliable predictors of temperature optimum. Freshwater fish had an average temperature optimum that was 4.5% higher than that of freshwater-brackish and freshwater-brackish-marine fish. Species tolerance to the temperature factors and nutrient loads correlated only with rheophily, with rheophilic species having an average 13.8% higher temperature tolerance than other fish species and a 10.4% higher chlorophyll-a concentration tolerance. The fish temperature index increased over time during the study period in all the studied water bodies, consistent with ongoing warming affecting all sites. In contrast, the Fish Eutrophication Index showed greater temporal heterogeneity in studied water bodies, indicating various adaptative potentials of fish communities to eutrophication. These indices can be relevant for assessing disturbed situations caused by changes in climatic and anthropogenic impacts on water bodies.

A review on sea cucumber (Bengali: Somuddro Sosha) as a bioindicator of heavy metal contamination and toxicity.

This review paper exhibits the underexplored realm of heavy metal contamination and associated risks in sea cucumbers (SCs), which hold significant importance in traditional Asian marine diets and are globally harvested for the Asian market. The assessment focuses on heavy metals (HMs) presence in various SC species, revealing a global trend in HMs concentrations across anatomical parts: Fe > Zn > As > Cu > Hg > Pb > Mn > Cr > Ni > Cd. Specific species, such as Eupentacta fraudatrix, Holothuria mammata, Holothuria polii, Holothuria tubulosa, and Holothuria atra, exhibit heightened arsenic levels, while Stichopus herrmanni raises concerns with mercury levels, notably reaching 3.75 mg/kg in some instances, posing potential risks, particularly for children. The study sheds light on anthropogenic activities such as cultivation, fishing, and shipping, releasing HMs into marine ecosystems and thereby threatening ocean and coastal environments due to the accumulation and toxicity of these elements. In response to these findings, the paper suggests SCs as promising bioindicator species for assessing metal pollution in marine environments. It underscores the adverse effects of human actions on sediment composition and advocates for ongoing monitoring efforts both at sea and along coastlines.

Continuous warming shifts the community pattern of periphytic protozoan fauna in marine environments.

Protozoan fauna is playing an important role in the functioning of microbial food webs by transferring the flux of material and energy from low to high tropic levels in marine ecosystems. To assess effects of elevated temperature on the marine ecosystem, periphytic protozoan communities were used as the test microbial fauna, and were incubated in a temperature-controlled circulation system in a successive temperature gradient of 22 (control), 25, 28, 31 and 34 °C. The results showed that: (1) the test microbial fauna was shifted in both species composition and community structure; (2) the average taxonomic distinctness represented a clear decreasing trend, (3) while the variation in taxonomic distinctness significantly increased with increase of water temperature; and (4) the community pattern was significantly departed from an expectation when temperature increased by 12 °C. These results suggested that Protozoa may be used as a useful bioindicator of global warming in marine ecosystems.

Effects of continuous warming on homogeneity of periphytic protozoan fauna in marine ecosystems.

As a powerful biological indicator, multivariate dispersion in a community is widely used to evaluate the biological evaluation of environmental heterogeneity. To investigate the effects of persistent warming on microbial fauna in marine environments, the periphytic protozoan communities were used as test organisms and incubated in five temperature-controlled circulation system at 22 (control), 25, 28, 31 and 34 °C, respectively. The results showed that (1) there was a clear variation in species occurrence, and the α-/γ-diversity measures decreased with the increase of temperatures; (2) the compositional pattern was significantly driven by the persistent warming compared to community pattern from species-abundance data; and (3) both traditional ß-diversity and multivariate dispersion measures on species compositional matrix were significantly correlative with changes in the temperature. Therefore, it is suggested that continuous temperature fluctuations have a greater impact on homogeneity of species composition of protozoan communities than that of their community structure.