Indicator Of Environmental Stress Research Articles

Response of periphytic diatom communities to multiple stressors influencing lakes in the Muskoka River Watershed, Ontario, Canada

Anthropogenic stressors, such as urban development and intensification of agricultural and industrial activities, can alter physical, chemical, and biological conditions in aquatic systems. Mounting concern over cumulative effects of multiple stressors has stimulated the need to track ecological responses and quantify degradation. Periphytic diatoms have potential to serve as early indicators of ecological degradation in aquatic systems. We examined relations between periphytic diatom community composition, water chemistry, and the magnitude of anthropogenic stressors in lakes of the Muskoka River watershed. These relations were used to develop a bioassessment framework for tracking changes in biological integrity in a region undergoing growth of tourism and related urban and recreational activities. We examined nearshore periphyton and water-chemistry samples from 86 lakes to assess relations between diatom community composition, water chemistry, and measures of 9 anthropogenic stressors (e.g., % urban area, % agricultural area, roadway proximity) based on uni- and multivariate numerical methods. Composition of periphytic diatom communities was associated with the concentration of ions from anthropogenic sources (i.e., road salt, dust suppressants). We demonstrated that periphytic diatoms in the nearshore regions of the lakes may be sensitive early warning indicators of ecological change because the most dramatic shift in diatom community composition was observed with modest increases in anthropogenic stressors. This relationship was weaker at sites where natural variation in pH among lakes was high. pH often acts in conjunction with other chemical factors to influence diatom community composition. Thus, we recommend stratifying monitoring efforts to account for confounding natural variation in pH. We anticipate that periphytic diatoms can be used as a powerful indicator of environmental stress in lakes beyond the MRW.

Spatial variability in sustainable development trajectories in South Africa: provincial level safe and just operating spaces

The Sustainable Development Goals (SDGs) represents the first globally agreed framework to address human development and environmental stewardship in an integrated way. One approach to summarising national SDG status is our “barometer for inclusive sustainable development in South Africa”. The barometer downscales global social and planetary boundaries to provide status and trends for 20 critical indicators of environmental stress and social deprivation. In this paper, we explore the sub-national heterogeneity in sustainable development indicators by creating barometers defining the ‘safe and just operating space’ for South Africa’s nine provinces. Our results show that environmental stress varies significantly and provinces need to focus on quite different issues. Although generally environmental stress is increasing, there are areas where it is decreasing, most notably, marine harvesting. Social deprivation results show more of a pattern with high levels of deprivation in employment, income and safety across the provinces, and historically disadvantaged provinces showing the most deprivation overall. Although deprivation is generally decreasing, there are notable exceptions such as food security in six provinces. Our provincial barometers and trend plots are novel in that they present comparable environmental and social data on key indicators over time for all South Africa’s provinces. They are visual tools that communicate the range of key challenges and risks that provincial governments face, and are non-specialist and accessible to a range of audiences. In addition, the paper provides a critical case study of spatial disaggregation of national data that is required for the SDGs implementation.

Determination of Poly-β-hydroxyalkanoate in Peat

ABSTRACTPoly-β-hydroxyalkanoate (PHA) is a prokaryotic energy reserve material that has been used as an indicator of environmental stress in aquatic bacteria. The following technique has been used to quantify PHA in peatland microorganisms. Peat samples were dried, digested in sulphuric acid to convert PHA into crotonic acid, and the resulting acid determined using organic acid high performance liquid chromatography (HPLC) and ultraviolet (UV) detection at 214 nm. This technique is suggested to have potential value as an indicator of environmental stress on peatland microorganisms, such as that caused by summer drought, or changes in soil nutrient availability, which are predicted consequences of climatic change.

Effects of interspecific interaction-linked habitat factors on moose resource selection and environmental stress

Resource selection of herbivores is a complex ecological process that operates in relation to biological or non-biological factors, which may affect the feeding and movement, and subsequently their spatial distribution and environmental stress. Here, we estimated moose (Alces alces cameloides) resource selection for habitat variables and the effect of interspecific interactions related to roe deer (Capreolus pygargus bedfordi) on its population distribution and environmental stress in the Khingan Mountain region of northeast China at local and regional scales. Different response patterns of moose resource selection, spatial distribution, and environmental stress to interspecific interaction-linked habitat factors were shown at the two scales. A general ecological chain, response of moose to interspecific interaction-linked habitat factors, was exhibited at the regional scale, and at the local scale, heterogeneous responses, linkages of habitat selection and environmental stress of moose population might be driven by different interspecific interaction patterns. Our study firstly suggested that moose resource selection, food availability, diet quality, population density and environmental stress indicators were impacted by interactions with the distribution of other sympatric herbivore species and showed differences in ecological response chains at various spatial scales. These findings are useful for sympatric herbivore assembly conservation, habitat quality monitoring and management.

Optode use to evaluate microbial planktonic respiration in oligotrophic ecosystems as an indicator of environmental stress

The suitability of O2 optodes to resolve the effects of global-change stressors on respiration of microbial planktonic assemblages from oligotrophic ecosystems was tested. With this aim, we first evaluated how O2 measurements with optodes on closed flasks depended on delayed temperature equilibration (hysteresis), which can bias actual measurements on samples not subjected to constant temperature. This must be addressed when using optodes for in situ measurements. Thus, we provide the mathematical tools to correct the effects of hysteresis on O2 measurements hence removing the constraints of maintaining a constant temperature over the long incubations required to measure respiration in oligotrophic ecosystems. Optodes proved suitable to resolve the effects of stressors such as CO2, temperature, thermal stratification, nutrient input, and ultraviolet radiation in different oligotrophic aquatic ecosystems. These experiments resulted in significant differences in microbial planktonic respiration for all stressors tested. From these results, we conclude that (1) optodes constitute a useful tool to make realistic measurements on samples subjected to natural (or experimental) ranges of temperature variability, and (2) microbial planktonic respiration measured with O2 optodes has the potential to be used as an ecological indicator for assessing the effects of environmental stress, even in oligotrophic aquatic ecosystems, where higher sensitivities are needed.

Fluctuating Asymmetry in Two Common Freshwater Fishes as a Biological Indicator of Urbanization and Environmental Stress within the Middle Chattahoochee Watershed

Deviations in bilateral symmetry or fluctuating asymmetry of an organism may result under environmental stressors that reduce developmental homeostasis and stability. Anthropogenic stressors such as increased urbanization can negatively impact environmental quality of aquatic ecosystems. Researchers have stressed the value in finding easy, accurate and inexpensive methods for assessing potential stress within ecosystems. Here we use fluctuating asymmetry (FA) as a useful quantitative tool in assessing the environmental quality and potential urban-based stressors within eight creeks of the Bull and Upatoi Creeks Watershed within the larger watershed of the Middle Chattahoochee. Using Geographic Information System (GIS), we characterize land-use patterns and a decreasing urbanization gradient as related to each creek’s eastward position from Columbus, Georgia. We collected two common fishes (redbreast sunfish; Lepomis auritus and bluegill; Lepomis macrochirus), measured both metric and meristic traits and investigated if the degree of FA in these two common fishes correlated with the urbanization gradient across creeks. We found significant differences in FA among creeks with one of the highest FA measures for the most urban creek. Principal component analysis (PCA) scores of urbanization and water chemistry were regressed against FA scores. We found no significant relationship between urbanization and FA nor environmental water chemistry and FA among creeks. We comment on the use of FA as a potential response variable and biological indicator of environmental stress within this watershed.

Early exposure to Aroclor 1254 invivo disrupts the functional synaptic development of newborn hippocampal granule cells.

Neurogenesis in the dentate gyrus is sensitive to endogenous and exogenous factors that influence hippocampal function. Ongoing neurogenesis and the integration of these new neurons throughout life thus may provide a sensitive indicator of environmental stress. We examined the effects of Aroclor 1254 (A1254), a mixture of polychlorinated biphenyls (PCBs), on the development and function of newly generated dentate granule cells. Early exposure to A1254 has been associated with learning impairment in children, suggesting potential impact on the development of hippocampus and/or cortical circuits. Oral A1254 (from the 6th day of gestation to postnatal day 21) produced the expected increase in PCB levels in brain at postnatal day 21, which persisted at lower levels into adulthood. A1254 did not affect the proliferation or survival of newborn neurons in immature animals nor did it cause overt changes in neuronal morphology. However, A1254 occluded the normal developmental increase in sEPSC frequency in the third post-mitotic week without altering the average sEPSC amplitude. Our results suggest that early exposure to PCBs can disrupt excitatory synaptic function during a period of active synaptogenesis, and thus could contribute to the cognitive effects noted in children exposed to PCBs.

Ecosystem indicators: Foraminifera, Thecamoebians and Diatoms from the Ologe Lagoon, Nigeria

The Ologe Lagoon in southwestern Nigeria is a natural habitat located closely to both residential and industrial estates. The lagoon is heavily affected by effluents of agricultural and industrial runoff including organochlorine compounds and heavy metals (chloropesticides, DDT and polychlorinated biphenyls, cadmium, manganese, zinc, copper, lead, iron and nickel). Ologe Lagoon is situated in a semi-isolated position and its brackish waters traverse several creeks and lagoons before it reaches the Atlantic Ocean. The lagoon experiences minor tidal but noticeable salinity and pH variations during the rainy season. During the dry season, however, the waters have a comparatively long resident time where sediments act as sink and aggregate contaminants over time. Investigations on benthic foraminifera, thecamoebian and diatom species were carried out to document the current status, composition, spatial distribution, and response of microfaunal assemblages to environmental stressors within the lagoon. The benthic foraminifer assemblage is composed of four highly specialized agglutinated species of Ammotium salsum, Miliammina fusca, Ammobaculites dilatatus and Ammobaculites aff. A. exiguus. They are present at all sample sites with varying abundances. The high abundance of Ammotium salsum is considered an indication of environmental stress. Thecamoebian species of Difflugia oblonga, Difflugia proteiformis and Pontigulasia compressa were also recorded in varying proportions and generally represent less than one percent of the total foraminifera/thecamoebian assemblage. The presence of marine brackish water larger siliceous diatoms of Actinoptychus and Campylodiscus species indicates an interaction between the lagoon and the marine waters although on the minimal scale with regards to actual salinity ranges. The faunal assemblages recovered are characterized by low species richness and alpha diversity indices and are typical of shallow, marginal-marine hyposaline environments. Numerical abundances and spatial distribution patterns suggest taxon-specific habitat preferences and highlight their potential for environmental monitoring studies.

Heavy metal contamination increases fluctuating asymmetry inRhus glabraL. (Anacardiaceae)

Abstract Fluctuating asymmetry—small random deviations from perfect bilateral symmetry—is commonly used as an indicator of environmental stress. I used the extent of fluctuating asymmetry in leaves to evaluate the degree to which heavy metal contamination has an observable phenotypic effect on the developmental stability of Rhus glabra (Anacardiaceae), the smooth sumac. Sumac from a deserted mining site near Picher, Oklahoma, displayed significantly greater size-corrected unsigned fluctuating asymmetry than that of sumac from a control site near Tulsa, Oklahoma. These results suggest that heavy metal contamination has a significant effect on the stability of developmental processes in R. glabra and suggest that fluctuating asymmetry may be used as an indicator of environmental pollution.

Effects of Salinity and Inundation on Microbial Community Structure and Function in a Mangrove Peat Soil

Shifts in microbial community function and structure can be indicators of environmental stress and ecosystem change in wetland soils. This study evaluated the effects of increased salinity, increased inundation, and their combination, on soil microbial function (enzyme activity) and structure (phospholipid fatty acid (PLFA) signatures and terminal restriction fragment length polymorphisms (T-RFLP) profiles) in a brackish mangrove peat soil using tidal mesocosms (Everglades, Florida, USA). Increased tidal inundation resulted in reduced soil enzyme activity, especially alkaline phosphatase, an increase in the abundance and diversity of prokaryotes, and a decline in number of eukaryotes. The community composition of less abundant bacteria (T-RFLPs comprising 0.3–1 % of total fluorescence) also shifted as a result of increased inundation under ambient salinity. Several key biogeochemical indicators (oxidation-reduction potential, CO2 flux, porewater NH4 +, and dissolved organic carbon) correlated with measured microbial parameters and differed with inundation level. This study indicates microbial function and composition in brackish soil is more strongly impacted by increased inundation than increased salinity. The observed divergence of microbial indicators within a short time span (10-weeks) demonstrates their usefulness as an early warning signal for shifts in coastal wetland ecosystems due to sea level rise stressors.

Fluctuating asymmetry in populations of the South American frog Physalaemus cuvieri (Leptodactylidae) in areas with different degrees of disturbance

ABSTRACTMethods to measure and monitor wild populations are important conservation tools in areas affected by anthropogenic disturbances. We compared three populations of the South American frog Physalaemus cuvieri Fitzinger, 1826 (Leptodactylidae) from areas with different degrees of anthropogenic disturbance in regard to their degrees of fluctuating asymmetry (FA). We selected four morphological characters (radio-ulna, femur, tibia-fibula and digit length) and compared two populations from relatively pristine areas with one population located in a highly urbanised and disturbed area. We found a significantly higher level of FA for the digit length, p < 0.05, in the population suffering the highest level of anthropogenic disturbance in relation to the two populations located in the pristine areas. There are no significant differences in the three populations in regard to FA for the radio-ulna, femur and tibia-fibula. The absence of FA in these three measurements might indicate a negative effect of limb asymmetry on this species survivorship. Our study provides a good example of the use of FA as indicator of environmental stress. However, this result must be viewed with some caution, since we observed FA in only one morphological character.

Assessment of biological effects of environmental pollution in Mersin Bay (Turkey, northeastern Mediterranean Sea) using Mullus barbatus and Liza ramada as target organisms

The increasing emphasis on the assessment and monitoring of marine ecosystems has revealed the need to use appropriate biological indicators for these areas. Enzyme activities and histopathology are increasingly being used as indicators of environmental stress since they provide a definite biological end-point of pollutant exposure. As part of an ecotoxicological assessment of Mersin Bay, EROD enzyme activity and histopathological response in selected organs and tissues of two species of fish, Mullus barbatus (red mullet) and Liza ramada (thinlip grey mullet), captured from area were examined. Pollutant (Organochlorines (OC), alkylphenols (APs) and BPA) levels and biomarker responses in tissue samples were evaluated together for their potential to alter the metabolism and cellular aspects in liver and gonad. Elevated induction of EROD activity and histopathological alterations in contaminated samples from Mersin Bay was observed compared to reference site indicating the exposure to potential pollutants.

Effect of Air Pollution on Leaf Traits of Three Tree Species Growing in the Industrial Zone of Jeddah, Saudi Arabia

Effect of air pollution in the industrial area of Jeddah city, Saudi Arabia on three tree species Camphor (Cinnamomum camphora), Henna (Lawsonia inermis), and Bougainvillea (Bougainvillea spectabilis) has been studied with special reference to characteristics of leaves. These plant species were chosen because they are common and in the industrial and control areas. leaf area, number of stomata, stomata length and width and stomata pore width and length of these plant species were investigated. The results of this study with all trees species showed significant decrease in plant leaf area and stomata number in the industrial zone comparing with the control area. The results of those tree species indicated marked alteration in epidermal traits, with increased stomata length and width and stomata pore width and length collected from industrial site than those from control site. These changes in the leaf area and epidermal traits could be as indicator of environmental stress and can be recommended in the industrial areas for the early detection of air pollution.

Classification of the spermatogenic cycle, seasonal changes of seminiferous tubule morphology and estimation of the breeding season of the large Japanese field mouse (Apodemus speciosus) in Toyama and Aomori prefectures, Japan.

The large Japanese field mouse, Apodemus speciosus, is a potential indicator of environmental stress, but this function has not been confirmed by histological studies. Since environmental stress affects the reproductive function of mice, we determined the reproductive characteristics of this species at two locations: Toyama (36°35ʹN, 137°24ʹE) and Aomori (40°35ʹN, 140°57ʹE). Mice were captured during May–November (n=119) and July–November (n=146) at these locations, respectively. We classified the breeding season from the numbers of pregnant females and young, in addition to the spermatogenic cycle and seasonal changes in seminiferous tubule morphology of males. Testicular weight was measured, and seminiferous tubule morphology was examined histologically. Fourteen stages were found in the seminiferous epithelium cycle based on acrosome formation and spermatid head morphology. At both locations, the breeding season peaked from late summer to early autumn and possibly in spring. Spermatogenic activity was classified into 4 periods from June to November: resting around June and October–November; resumptive around July; active around August; and degenerative around September. During the resting period, the seminiferous tubules consisted of Sertoli cells, spermatogonia and spermatocytes. Spermatogenesis began during the resumptive period, and spermatids were observed. During the active period, active spermatogenesis and a broad lumen were observed. During the degenerative period, spermatogenesis ended, and Sertoli cells, spermatogonia, spermatocytes and degenerating exfoliated round spermatids were observed. This study provides scientific information about the testicular histopathological evaluations of the large Japanese field mouse for its use as an index species of environmental pollution.

Mycorrhizal Fungal Community of Poplars Growing on Pyrite Tailings Contaminated Site near the River Timok

Background and Purpose: Mycorrhizal fungi are of high importance for functioning of forest ecosystems and they could be used as indicators of environmental stress. The aim of this research was to analyze ectomycorrhizal community structure and to determine root colonization rate with ectomycorrhizal, arbuscular mycorrhizal and endophytic fungi of poplars growing on pyrite tailings contaminated site near the river Timok (Eastern Serbia). Materials and Methods: Identification of ectomycorrhizal types was performed by combining morphological and anatomical characterization of ectomycorrhizae with molecular identification approach, based on sequencing of the nuclear ITS rRNA region. Also, colonization of poplar roots with ectomycorrhizal, arbuscular mycorrhizal and dark septated endophytic fungi were analysed with intersection method. Results and Conclusions: Physico-chemical analyses of soil from studied site showed unfavourable water properties of soil, relatively low pH and high content of heavy metals (copper and zinc). In investigated samples only four different ectomycorrhizal fungi were found. To the species level were identified Thelephora terrestris and Tomentella ellisi, while two types remained unidentified. Type Thelephora terrestris made up 89% of all ectomycorrhizal roots on studied site. Consequently total values of Species richness index and Shannon-Weaver diversity index were 0.80 and 0.43, respectively. No structures of arbuscular mycorrhizal fungi were recorded. Unfavourable environmental conditions prevailing on investigated site caused decrease of ectomycorrhizal types diversity. Our findings point out that mycorrhyzal fungal community could be used as an appropriate indicator of environmental changes.

Caddisflies (Trichoptera) as good indicators of environmental stress in mountain lotic ecosystems

We analysed the influence of environmental stress (mainly deforestation of catchment due to windstorm) on taxonomic structure as well as composition of functional groups (FG) based on zonation preferences and feeding types of caddisfly species in 11 streams (12 sites) with various environmental conditions situated in the High Tatra Mts, Slovakia. Us- ing Spearman correlation, we confirmed an expected positive association between taxonomic and functional groups richness (Ri), diversity (Shannon - Wiener Index) (Di) and equitability (Eq), but not with habitat diversity (HQA indices). By test- ing measured physiographical, physico-chemical and hydromorphological factors using CCA analysis we found that stream order and temperature best explained the functional and taxonomic structure of caddisfly assemblages. The occurrence of Rhyacophila glareosa decreased with increasing daily mean water temperature positively correlated with deforestation, whereas R. tristis (dominating at sites most affected by erosion) showed the opposite pattern. Composition of functional groups based on zonation preferences and feeding types distinguished well near natural sites from impacted ones, domi- nated by crenal/rhithral predators, and explained more of the overall variance of the species-environment relationships than taxonomic composition of caddisfly assemblages.

Gill asymmetry in &lt;i&gt;Labeo ogunensis from Ogun river, Southwest Nigeria

Fluctuating asymmetry (FA), often used as indicator of environmental stress, was evaluated in gill rakers and filaments of Labeo ogunensis from Ogun river, Southwest Nigeria. Mean length and weight of 13.68 +/- 1.28 cm and 59.40+17.48 g were respectively recorded. The gill rakers (t = -0.919) and filaments (t = -1.150) from both sides were not significantly different. The gill filaments recorded (0.31 +/- 2.42) higher incidence of fluctuating asymmetry (FA) compared with the gill rakers (0.21 +/- 1.58), signifying developmental interference in the population. Fish size and sex were observed to exert minimal influence on FA.

Directional and fluctuating asymmetries in domestic pig skulls

Morphological symmetry and asymmetry of three different sheep geographical populations (n=39), managed under semi-extensive conditions, were decomposed using geometric morphometric methods, on dorsal aspect of skulls. Fluctuating asymmetry (FA) was used as an indicator of environmental stress, and directional asymmetry (DA) as biomechanical constraints. The two-dimensional coordinates of 21 landmarks were digitized and analyzed using geometric morphometrics. Multivariate analyses show ed the presence of subtle but significant directional asymmetry and fluctuating asymmetry in the entire sample, but no distinctive differences were detected between populations. These results are on the whole indicative that environmental stress, if present was not sufficient to infer on symmetry of the skull, and no alterations could be noted on functional loadings. On the whole morphometric studies should open up promising areas of research in this almost unexplored field, in domestic ungulates.

Are changes in the structure of nematode assemblages reliable indicators of moderate petroleum contamination?

This study assesses through a multiple before-after-control-impact (MBACI) design the effects of diesel oil on the structure of nematode assemblages in unvegetated tidal flats of a subtropical estuary. Oil-exposed treatments were contrasted with controls for a duration of four successive days before and after an experimental spill in three distinct areas of the Paranaguá Estuarine Complex (Southern Brazil). No significant differences were observed in nematode total density, number of taxa and the overall assemblage structure between the control and impact treatments from before to after the experimental spill. This reinforces the idea that, despite being good indicators of environmental stress, free-living marine nematodes are able to tolerate low concentrations of hydrocarbons and to survive in moderately contaminated areas. We also show that robust experimental designs are useful to avoid confounding expected natural variability with the effects of a mild impact.

An Exploratory Analysis of Stream Teratogenicity and Human Health Using Zebrafish Whole-Sediment Toxicity Test

This study demonstrates a novel application of effect-based toxicity testing for streams that may provide indications of co-perturbation to ecological and human health. For this study, a sediment contact assay using zebrafish (Danio rerio) embryos was adapted to serve as an indicator of teratogenic stress within river sediments. Sediment samples were collected from Lake Michigan tributary watersheds. Sediment contact assay responses were then compared to prevalence of congenital heart disease (CHD) and vital statistic birth indicators aggregated from civil divisions associated with the watersheds. Significant risk relationships were detected between variation in early life-stage (ELS) endpoints of zebrafish embryos 72 h post-fertilization and the birth prevalence of human congenital heart disease, low birthweight and infant mortality. Examination of principal components of ELS endpoints suggests that variance related to embryo heart and circulatory malformations is most closely associated with human CHD prevalence. Though toxicity assays are sometimes used prospectively, this form of investigation can only be conducted retrospectively. These results support the hypothesis that bioassays normally used for ecological screening can be useful as indicators of environmental stress to humans and expand our understanding of environmental–human health linkages.