Qualitative status of the environment is signaled by a group of indicators, known as bioindicators, several of which are responsible for showing progressive impacts of different types of pollutants. Having addressed the influence of various bioindicators in environmental pollution, it has been revealed that bioindicators are sensitive to any disturbance in any environment. With regards to the pollution, the quality of an ecosystem can be judged by an organism, which is actually an indicator and play a key role in monitoring its changes. A reliable and cost effective way to evaluate the changes in the environment is possible by means of indicator species as ecological indicators, yet selecting a specific indicator poses a real challenge, followed by its identification as well as relation among indicators and their particular applications. As a result, environmental, ecological, and biodiversity indicators fulfill their goal of monitoring environmental quality. The current situation requires cost effective bioindicators along with their reliability to detect and mitigate the impacts of pollution in our environment.

Moss (as a reference material) and camphor (Cinnamomum Camphora) leaf, branch bark and bark samples were systematically collected across an urban-rural gradient in Guiyang (SW China) to determine the efficacy of using these bio-indicators to evaluate nitrogen (N) pollution. The tissue N concentrations (0.13%–2.70%) and δ¹⁵N values (−7.5‰ to +9.3‰) of all of these bio-indicators exhibited large spatial variations, as they recorded higher values in urban areas that quickly decreased with distance from the city center; moreover, both soil N concentrations and soil δ¹⁵N values were found no significant differences within each 6 km from the urban to the rural area. This not only suggests that the different N uptake strategies and variety of N responses of these bio-indicators can be reflected by their different susceptibilities to variations in N deposition but also reveals that they are able to indicate that urban N deposition is mostly from traffic and industry (NOₓ-N), whereas rural N deposition is mainly from agriculture (NHₓ-N). Compared to previously collected urban moss and camphor leaf samples, the significantly increased δ¹⁵N values in current urban moss and camphor leaf samples further indicate a greater contribution of NOₓ-N than NHₓ-N to urban N deposition. The feasibility of using the N concentrations and δ¹⁵N values of branch bark and bark as biomarkers of N deposition thus was further confirmed through the comparative use of these bio-indicators. It can be concluded that vascular plant leaves, branch bark and bark can be used as useful biomonitoring tools for evaluating atmospheric N pollution. For further study, quantitative criteria for the practical use of these bio-indicators in response to N deposition should be developed and the differences in the δ¹⁵N values of different plant parts should also be considered, particularly in urban environments that are severely disrupted by atmospheric pollution.

Adult coho salmon (Oncorhynchus kisutch) prematurely die when they return from the ocean to spawn in urban watersheds throughout northwestern North America. The available evidence suggests the annual mortality events are caused by toxic stormwater runoff. The underlying pathophysiology of the urban spawner mortality syndrome is not known, and it is unclear whether closely related species of Pacific salmon are similarly at risk. The present study co-exposed adult coho and chum (O. keta) salmon to runoff from a high traffic volume urban arterial roadway. The spawners were monitored for the familiar symptoms of the mortality syndrome, including surface swimming, loss of orientation, and loss of equilibrium. Moreover, the hematology of both species was profiled by measuring arterial pH, blood gases, lactate, plasma electrolytes, hematocrit, and glucose. Adult coho developed behavioral symptoms within a few hours of exposure to stormwater. Various measured hematological parameters were significantly altered compared to coho controls, indicating a blood acidosis and ionoregulatory disturbance. By contrast, runoff-exposed chum spawners showed essentially no indications of the mortality syndrome, and measured blood hematological parameters were similar to unexposed chum controls. We conclude that contaminant(s) in urban runoff are the likely cause of the disruption of ion balance and pH in coho but not chum salmon. Among the thousands of chemicals in stormwater, future forensic analyses should focus on the gill or cardiovascular system of coho salmon. Because of their distinctive sensitivity to urban runoff, adult coho remain an important vertebrate indicator species for degraded water quality in freshwater habitats under pressure from human population growth and urbanization.

As a transitional zone between riverine and marine environments, an estuary plays an important role for the sources, accumulation and transport of microplastics. Although estuarine environments are hotspots of microplastic pollution, the correlation between microplastic pollution and aquatic organisms is less known. Here we investigated microplastic pollution in wild oysters Saccostrea cucullata from 11 sampling sites along the Pearl River Estuary in South China. The microplastic abundances in oysters ranged from 1.4 to 7.0 items per individual or from 1.5 to 7.2 items per gram tissue wet weight, which were positively related to those in surrounding waters. The oysters near urban areas contained significantly more microplastics than those near rural areas. Fibers accounted for 69.4% of the total microplastics in oysters. Microplastic sizes varied from 20 to 5000 μm and 83.9% of which were less than 100 μm. Light color microplastics were significantly more common than dark color ones. Based on the results, oysters are recommended as a biomonitor for the microplastic pollution in estuaries.

Due to the activities inherent to medical care units, the hospital effluent released contains diverse contaminants such as tensoactives, disinfectants, metals, pharmaceutical products and chemical reagents, which are potentially toxic to the environment since they receive no treatment or are not effectively removed by such treatment before entering the drain. They are incorporated into municipal wastewater, eventually entering water bodies where they can have harmful effects on organisms and can result in ecological damage. To determine the toxicological risk induced by this type of eflluents, eight metals and 11 pharmaceuticals were quantified, in effluent from a hospital. Developmental effects, teratogenesis and oxidative stress induction were evaluated in two bioindicator species: Xenopus laevis and Lithobates catesbeianus. FETAX (frog embryo teratogenesis assay–Xenopus) was used to obtain the median lethal concentration (LC50), effective concentration inducing 50% malformation (EC50), teratogenic index (TI), minimum concentration to inhibit growth (MCIG), and the types of malformation induced. Twenty oocytes in midblastula transition were exposed to six concentrations of effluent (0.1, 0.3, 0.5, 0.7, 0.9, 1%) and negative and positive (6-aminonicotinamide) controls. After 96 h of exposure, diverse biomarkers of oxidative damage were evaluated: hydroperoxide content, lipid peroxidation, protein carbonyl content, and the antioxidant enzymes superoxide dismutase and catalase. TI was 3.8 in X. laevis and 4.0 in L. catesbeianus, both exceed the value in the FETAX protocol (1.2), indicating that this effluent is teratogenic to both species. Growth inhibition was induced as well as diverse malformation including microcephaly, cardiac and facial edema, eye malformations, and notochord, tail, fin and gut damage. Significant differences relative to the control group were observed in both species with all biomarkers. This hospital effluent contains contaminants which represents a toxic risk, since these substances are teratogenic to the bioindicators used. The mechanism of damage induction may be associated with oxidative stress.

A long-term study on a benthic community was conducted in two different localities, one in semi-enclosed bay of Jinhae (n = 10, south coast) and the other in open sea area of Samcheok (n = 10, east coast), Korea, respectively. We aimed to identify the spatiotemporal patterns of macrozoobenthos and the environmental variables influencing such patterns in the two contrasting habitats. The macrozoobenthos assemblages on the soft bottom of the subtidal zone were analyzed over the 3 years, encompassing 12 consecutive seasons, in 2013–2016. Among the 22 environmental variables measured, organic matter, dissolved oxygen, mean grain size, and water depth showed clear differences between two study areas. Accordingly, several ecological indices (such as the number of species, abundance, dominant species, and diversity index (H’)) generally reflected site-specific benthic conditions. The macrofaunal community in the Jinhae showed typical seasonal fluctuations, whereas the Samcheok community showed no significant change over time and space. Region- or site-dependent temporal variabilities of macrofaunal assemblages are depicted through cluster analysis (CA), indicating distinct temporal changes in the composition of dominant species. In particular, the abundance of some dominant species noticeably declined in certain seasons when several opportunistic species peaked. Such faunal succession might be explained by significant changes to specific environmental factors, such as bottom dissolved oxygen, grain size, and water depth. Principle component analysis further identified major environmental factors, i.e., sediment properties in Jinhae and water quality parameters in Samcheok community, respectively. In addition, discriminant analysis confirmed the presence of several site-specific parameters for the faunal assemblage groups identified through CA. Finally, indicator value analysis identified species that were representative across stations and regions in accordance with their habitat preference and/or species tolerance. Overall, the two contrasting nearshore habitats showed distinct community differences, in time and space, that were influenced by site-dependent environmental conditions.

The Mediterranean Sea has been described as one of the most affected areas by marine litter in the world. Although effects on organisms from marine plastic litter ingestion have been investigated in several oceanic areas, there is still a lack of information from the Mediterranean Sea. The main objectives of this paper are to review current knowledge on the impact of marine litter on Mediterranean biodiversity, to define selection criteria for choosing marine organisms suitable for use as bioindicator species, and to propose a methodological approach to assessing the harm related to marine litter ingestion in several Mediterranean habitats and sub-regions. A new integrated monitoring tool that would provide the information necessary to design and implement future mitigation actions in the Mediterranean basin is proposed.According to bibliographic research and statistical analysis on current knowledge of marine litter ingestion, the area of the Mediterranean most studied, in terms of number of species and papers in the Mediterranean Sea is the western sub-area as well as demersal (32.9%) and pelagic (27.7%) amongst habitats.Applying ecological and biological criteria to the most threatened species obtained by statistical analysis, bioindicator species for different habitats and monitoring scale were selected. A threefold approach, simultaneously measuring the presence and effects of plastic, can provide the actual harm and sub-lethal effects to organisms caused by marine litter ingestion. The research revealed gaps in knowledge, and this paper suggests measures to close the gap. This and the selection of appropriate bioindicator species would represent a step forward for marine litter risk assessment, and the implementation of future actions and mitigation measures for specific Mediterranean areas, habitats and species affected by marine litter ingestion.

The phenolic compounds have posed public concern for potential threats to human health and ecosystem. Tert-butylphenols (TBPs), as one group of emerging contaminants, showed potential endocrine disrupting effects and aquatic toxicities. In the present study, we detected concentrations of 2,4-DTBP ranging from <0.001 to 0.057 μg/L (detection limit: 0.001 μg/L) in drinking water source from the Qiantang River in East China in April 2016. The endocrine disrupting effects of 2-TBP, 2,4-DTBP and 2,6-DTBP toward human estrogen receptor α (ERα), androgen receptor (AR) and thyroid hormone receptor β (TRβ) were evaluated using human recombinant two-hybrid yeast bioassay. Their aquatic toxicities were investigated with indicator organisms including Photobacterium phosphoreum, Vibrio fischeri and freshwater green alga Chlamydomonas reinhardtii. 2-TBP and 2,4-DTBP exhibited moderate antagonistic effects toward human ERα and AR in a concentration-dependent manner. 2-TBP significantly inhibited the light emission of P. phosphoreum. 2-TBP, 2,4-DTBP and 2,6-DTBP significantly inhibited the growth of C. reinhardtii and reduced the chlorophyll content. Our results suggest the potential adverse effects of TBPs on human health and aquatic organisms. The data will facilitate further risk assessment of TBPs and related contaminants.

Ecological effects of atmospheric nitrogen (N) and sulfur (S) deposition on two hardwood forest sites in the eastern United States were simulated in the context of a changing climate using the dynamic coupled biogeochemical/ecological model chain ForSAFE-Veg. The sites are a mixed oak forest in Shenandoah National Park, Virginia (Piney River) and a mixed oak-sugar maple forest in Great Smoky Mountains National Park, Tennessee (Cosby Creek). The sites have received relatively high levels of both S and N deposition and the climate has warmed over the past half century or longer. The model was used to evaluate the composition of the understory plant communities, the alignment between plant species niche preferences and ambient conditions, and estimate changes in relative species abundances as reflected by plant cover under various scenarios of future atmospheric N and S deposition and climate change. The main driver of ecological effects was soil solution N concentration. Results of this research suggested that future climate change might compromise the capacity for the forests to sustain habitat suitability. However, vegetation results should be considered preliminary until further model validation can be performed. With expected future climate change, preliminary estimates suggest that sustained future N deposition above 7.4 and 5.0 kg N/ha/yr is expected to decrease contemporary habitat suitability for indicator plant species located at Piney River and Cosby Creek, respectively.

Sewage input and the relationship between chemical markers (linear alkylbenzenes and coprostanol) and fecal indicator bacteria (FIB, Escherichia coli and enterococci), were evaluated in order to establish thresholds values for chemical markers in suspended particulate matter (SPM) as indicators of sewage contamination in two subtropical estuaries in South Atlantic Brazil. Both chemical markers presented no linear relationship with FIB due to high spatial microbiological variability, however, microbiological water quality was related to coprostanol values when analyzed by logistic regression, indicating that linear models may not be the best representation of the relationship between both classes of indicators. Logistic regression was performed with all data and separately for two sampling seasons, using 800 and 100 MPN 100 mL⁻¹ of E. coli and enterococci, respectively, as the microbiological limits of sewage contamination. Threshold values of coprostanol varied depending on the FIB and season, ranging between 1.00 and 2.23 μg g⁻¹ SPM. The range of threshold values of coprostanol for SPM are relatively higher and more variable than those suggested in literature for sediments (0.10–0.50 μg g⁻¹), probably due to higher concentration of coprostanol in SPM than in sediment. Temperature may affect the relationship between microbiological indicators and coprostanol, since the threshold value of coprostanol found here was similar to tropical areas, but lower than those found during winter in temperate areas, reinforcing the idea that threshold values should be calibrated for different climatic conditions.