Anthropogenic Environmental Stress Research Articles

A pollinator crisis can decrease plant abundance despite pollinators being herbivores at the larval stage

Pollinating insects are decreasing worldwide due to various environmental stresses (so-called pollinator crisis), raising concerns that plant productivity could be undermined in natural and agricultural ecosystems. To date, however, few studies have reported a concurrent decline in both pollinators and plants, and little is known about when a “plant crisis” occurs. Here, we propose that anthropogenic environmental stresses on pollinating insects (e.g. climate change, habitat loss, and pesticide usage) can negatively affect herbivorous insects (e.g., pollinator larvae and crop pests) as well, and effects of pollinator declines may be masked by positive effects of herbivore declines. To test the idea, we theoretically investigated plant population dynamics mediated by two insect groups: one representing a pollinator that is mutualistic at the adult stage but antagonistic at the larval stage, and the other representing a non-structured pest herbivore. Our model revealed that environmental stresses (increasing insect mortality) can have counterintuitive effects on plants. Nonetheless, plant abundance generally decreases with decreasing pollinator abundance, especially when plant populations grow slowly without pollinators, when pollinators are effective mutualists, or when pollinators are susceptible to environmental stresses. These findings offer a theoretical basis for assessing the pollinator crisis for biodiversity conservation and agricultural management.

Introducing energy into marine environments: A lab-scale static magnetic field submarine cable simulation and its effects on sperm and larval development on a reef forming serpulid

Non-chemical sources of anthropogenic environmental stress, such as artificial lights, noise and magnetic fields, are still an underestimate factor that may affect the wildlife. Marine environments are constantly subjected to these kinds of stress, especially nearby to urbanized coastal areas. In the present work, the effect of static magnetic fields, associated with submerged electric cables, was evaluated in gametes and early life stages of a serpulid polychaete, namely Ficopomatus enigmaticus. Specifically, biochemical/physiological impairments of sperm, fertilization rate inhibition and incorrect larval development were assessed. We evaluated differences between two selected magnetic field induction values (0.5 and 1 mT) along a range of exposure times (30 min–48 h), for a sound evaluation on this species. We found that a magnetic induction of 1 mT, a typical value that can be found at distance of tens of cm from a submerged cable, may be considered a biologically and ecologically relevant for sessile organisms and for coastal environments more generally. This value exerted statistically significant effects on membranes, DNA integrity, kinetic parameters and mitochondrial activity of sperm cells. Moreover, a significant reduction in fertilization rate was observed in sperm exposed to the same magnetic induction level (1 mT) for 3 h, compared to controls. Regarding early larval stages, 48-h exposure did not affect the correct development. Our results represent a starting point for a future focus of research on magnetic field effects on early life stages of aquatic invertebrates, using model species as representative for reef-forming/encrusting organisms and ecological indicators of soft sediment quality.

Spatio-temporal estimation of the anthropogenic environmental stress intensity in the Three-River-Source National Park region, China

Through the construction of national parks to optimize the ecological, production and living space structures, ecological assets can be converted into ecological product values under the premise of maximizing the protection of the original natural ecological environment. In this way, multiple regional economic, social and ecological benefits can be realized. Of course, unreasonable and high-intensity production and living (tourism) activities of human beings will cause irreversible negative effects. Therefore, paying attention to the environmental stress process and its spatial effects brought about by human activities under the background of national park construction is of great significance for coordinating the man-land coupling system and improving the sustainability of key eco-function zones. Taking the Three-River-Source National Park (TRSNP) region as a typical case study, based on the spatial identification of anthropogenic pollution and the estimation of water and air pollutant emissions, this study quantitatively evaluates the environmental stress intensity and analyzes its spatial effects from the perspective of “point-line-plane” stress characteristics. The results show that the effect of environmental stress from anthropogenic pollutants on the TRSNP region is relatively low but shows significant spatial differentiation. The stress intensity in central cities (towns) is relatively high, and the four counties where national parks are located account for only 1/2 of the average stress intensity. From 2012 to 2016, urbanization and industrialization showed significant “point-like” environmental stress; agriculture and animal husbandry production increased the “plane-like” stress; and tourism and transportation showed a “line-like” stress, shifting from points to lines. It is recommended to formulate management and control measures to alleviate the environmental stress intensity in important ecological function areas from four aspects: improving the carrying capacity of environmental facilities, establishing a functional zoning control system, implementing environmental regulations for production and living, and standardizing the environmental ethics and moral concepts of the whole society.

Analyzing the Role of Increasing Water Pollution on Species-Richness, Interspecific-Competition and Abundance-Unevenness in Reef-Associated Fish Communities, off Jakarta Bay (Indonesia)

Not far from the exceptionally rich ‘Coral Triangle’ on the one hand but, on the other hand, exposed to strongly varying degree of anthropogenic environmental stresses, the reef-associated fish assemblages all along ‘Seribu Islands’ (off Jakarta Bay) are, thus, confronted to both positive and negative ecological influences. As such, these fish assemblages offer especially interesting opportunities to analyze these opposite ecological influences, at both the descriptive and the functional points of views. The least-biased numerical extrapolation of a series of recently reported – yet incomplete – samplings has allowed a sub-exhaustive account of both the estimated total species-richness and the completed distribution of species abundances – including the set of those rarer species which had remained unrecorded. Thanks to this numerically completed information, it became possible to tackle some important issues – which otherwise would have remained difficult to address properly. First, a remarkably good correlation was highlighted between the distance of fish assemblages to Jakarta Bay (distance considered as a reliable surrogate to the improvement of environmental conditions for fish assemblages) and a theoretically derived index characterizing the accommodation capacity of sites for fish assemblages. This good correlation suggests that this index offer a way to reliably accounts for the “environmental quality” of marine waters, as appreciated by fish communities. In quite another respect, comparing primary and secondary-feeding guilds, provides still further empirical support to a seemingly common trend according to which the guild of secondary-feeders features usually more species-rich, while exhibiting less interspecific competition intensity at niche overlaps, than does the primary-feeders guild.

Extrinsic stressors modulate resource evaluations: insights from territoriality under artificial noise

BackgroundCompetition is considered to rely on the value attributed to resources by animals, but the influence of extrinsic stressors on this value remains unexplored. Although natural or anthropogenic environmental stress often drives decreased competition, assumptions that this relies on resource devaluation are without formal evidence. According to theory, physiological or perceptual effects may influence contest behaviour directly, but motivational changes due to resource value are expected to manifest as behavioural adjustments only in interaction with attainment costs and resource benefits. Thus, we hypothesise that stressor-induced resource devaluations will impose greater effects when attainment costs are high, but not when resource benefits are higher. Noise may elicit such effects because it impacts the acoustic environment and imposes physiological and behavioural costs to animals. Therefore, we manipulated the acoustic environment using playbacks of artificial noise to test our hypotheses in the territorial male Siamese fighting fish, Betta splendens.ResultsCompared to a no-playback control, noise reduced defense motivation only when territory owners faced comparatively bigger opponents that impose greater injury costs, but not when territories also contained bubble nests that offer reproductive benefits. In turn, nest-size decreases were noted only after contests under noise treatment, but temporal nest-size changes relied on cross-contest variation in noise and comparative opponent size. Thus, the combined effects of noise are conditional on added attainment costs and offset by exceeding resource benefits.ConclusionOur findings provide support for the hypothesised modulation of resource value under extrinsic stress and suggest implications for competition under increasing anthropogenic activity.

Genetic structure of Turbinaria peltata in the northern South China Sea suggest insufficient genetic adaptability of relatively high-latitude scleractinian corals to environment stress

With the rapid degradation of coral reefs due to global warming and anthropogenic impacts, relatively high-latitude areas, such as the northern South China Sea (SCS), are likely to become refuges for tropical coral species. Here we investigated the genetic features and adaptability of one dominant scleractinian coral species, Turbinaria peltata, in the northern SCS. A total of 81 samples from 5 sites were studied to explore potential mechanisms of adaptability to environmental stress as a result of climate change. Ten microsatellite markers developed in this study, one nuclear gene (internal transcribed spacer, ITS), and one mitochondrial gene (mitochondrial cytochrome oxidase subunit I gene, mtDNA COI) were used. Our results indicated that the genetic diversity of T. peltata in the northern SCS is low (Ar = 1.403–2.011, Ho = 0.105–0.248, He = 0.187–0.421) with the lowest in Dongfang population (DF) (Ar = 1.403, Ho = 0.22, He = 0.187). These results indicate that T. peltata has insufficient genetic adaptability and may unable to handle increasingly complex global changes. A significantly moderate genetic differentiation was observed among T. peltata populations (ΦST = 0.167), in addition to a high genetic differentiation between DF and other populations (FST = 0.272–0.536 > 0.25). The DF population near a fishing port was exposed to severe anthropogenic environmental stress, which may drive the extraordinarily high genetic differentiation between DF and other populations. Furthermore, the Mantel test results showed that the genetic differentiation of the other four populations was strongly correlated with the average sea surface temperature (SST) (R2 = 0.82, Mantel test P < 0.05) and geographical distance (R2 = 0.57, Mantel test P < 0.05). Our results suggest that the genetic structure of T. peltata in the relatively high-latitude of the SCS was significantly affected by average SST, geographical isolation, and anthropogenic activities. These findings provide a theoretical foundation for the protection of relatively high-latitude coral reefs.

Reducing anthropogenic environmental stresses: A review on cleaner production and industrial ecology

AbstractCleaner production (CP) provides source control measures of minimizing the waste and emissions occurred by the production and processes. CP, which is also known by the term pollution prevention (P2), has been practiced for several years among various countries across the world. Practicing of CP in industries supports in optimization of materials utilization, lowering the energy consumption, and the reduction of emissions to air, water, and soil. CP provides a continuous and preventive environmental improvement for the organizations by focusing on the prevention rather than providing solutions, once the pollution has been occurred. Implementing CP in a business requires support from the employees from top to bottom levels in the hierarchy, to obtain a successful and long‐term outcome. Thus, CP is no longer considered as a standalone process and should be integrated in the entire business development activities, in order to improve the quality of life. CP can also be identified as a subset of industrial ecology, which focuses on designing the industrial processes, products, and services, in order to minimize the environmental concerns of the industrial activities. This article will provide an overview of the background of CP, the CP assessment methodology, and the concepts of industrial ecology.

Wavelength-specific artificial light disrupts molecular clock in avian species: A power-calibrated statistical approach

Nighttime lighting is an increasingly important anthropogenic environmental stress on plants and animals. Exposure to unnatural lighting environments may disrupt the circadian rhythm of organisms. However, the sample size of relevant studies, e.g. disruption of the molecular circadian clock by light pollution, was small (<10), which led to low statistical power and difficulties in replicating prior results. Here, we developed a power-calibrated statistical approach to overcome these weaknesses. The results showed that the effect size of 2.48 in clock genes expression induced by artificial light would ensure the reproducibility of the results as high as 80%. Long-wavelength light (560–660 nm) entrained expressions of the positive core clock genes (e.g. cClock) and negative core clock genes (e.g. cCry1, cPer2) in robust circadian rhythmicity, whereas those clock genes were arrhythmic in short-wavelength light (380–480 nm). Further, we found artificial light could entrain the transcriptional-translational feedback loop of the molecular clock in a wavelength-dependent manner. The expression of the positive core clock genes (cBmal1, cBmal2 and cClock), cAanat gene and melatonin were the highest in short-wavelength light and lowest in long-wavelength light. For the negative regulators of the molecular clock (cCry1, cCry2, cPer2 and cPer3), the expression of which was the highest in long-wavelength light and lowest in short-wavelength light. Our statistical approach opens new opportunities to understand and strengthen conclusions, comparing with the studies with small sample sizes. We also provide comprehensive insight into the effect of wavelength-specific artificial light on the circadian rhythm of the molecular clock in avian species. Especially, the global lighting is shifting from “yellow” sodium lamps, which is more like the long-wavelength light, toward short-wavelength light (blue light)-enriched “white” light-emitting diodes (LEDs).

Analysing the Role of Environmental Stresses on Species Richness and the Process of Hierarchical Structuring of Species Abundances in Marine Gastropods communities at Suva (Fiji Islands)

Anthropogenic environmental stresses, especially physio-chemical pollution, are causing steadily increasing threat to many ecosystems, among which coastal marine communities in tropical shallow waters are especially sensitive. In particular, species-rich marine gastropod assemblages are doomed to bear sharp drops in species diversity when exposed to pollutants released offshore. Yet, the details of the process of decline in species diversity remain to be addressed and analysed more deeply. By addressing a series of previously reported inventories of marine gastropod communities along a sharp gradient of pollution along southern coast at Suva (Fiji Archipelago), I first confirm the already recognised trend towards both a severe decrease in species richness and a strong increase of the unevenness in species abundance distribution, as a response to incremental pollution. Yet, the last trend – increased unevenness – reveals being essentially the purely mathematical consequence of the concomitant decline in species richness. In fact, the genuine intensity of the process of hierarchical structuring of species abundances proves remaining virtually unaffected by environmental degradation, contrary to what has been generally thought so far. Also, another unexpected aspect of the decline in species richness with growing pollution is that this decline is far from being primarily restricted to the set of rarest species; in fact, the originally abundant species are also largely implied in this decline.&#x0D; Moreover, considering separately the two co-occurring feeding guilds, it is shown that herbivores and carnivores are substantially involved the same in the drop in species diversity; as a result, their relative contributions in the community do not seem markedly contrasted by growing pollution. In another respect, a recently proposed paradigmatic hypothesis is supported, according to which the herbivore-guild has quite less numerous species with more unevenly distributed abundances, as compared to the carnivore-guild. Yet, once again, this increased unevenness is essentially the purely mathematical consequence of the concomitant decline in species richness; the genuine intensity of the process of hierarchical structuring of species abundances does remain substantially unchanged. At last, a comparatively extremely high sensitivity to pollution is highlighted for the emblematic genus Conus, which suffers, here, a dramatic drop in species diversity.

Effect of honey harvest on the activities of Melipona (Melikerria) fasciculata Smith, 1854 workers

The foraging behavior of stingless bees is related to the availability of resources and the needs of the colony. Stingless bees have preferences for specific resources to maintain the nest which can change in response to natural or anthropogenic environmental stresses such as the harvesting of honey. To understand their behavior after traditional honey harvest, six colonies of Melipona fasciculata were monitored during three different periods. Foraging standards and biometric parameters of the colonies were determined during the period before honey harvest (PI) and 5 and 35 d after the honey harvest (PII and PIII, respectively). The amount of foraging activity significantly increased after the harvest with the colonies preferring nectar for food and mud or resin for rebuilding the colony. During PIII, foraging activity re-stabilized with the workers being less active, similar to that in PI, and revealed a trade-off between required resources over a short period. Most of the foraging bees were classified as specialists, and this did not vary in response to the harvest. The colonies responded defensively to honey extraction, with more workers acting as guards after the harvest.

Coping with environmental stress: The effects of wastewater pollutants on energy stores and leptin levels in insectivorous bats

Anthropogenic environmental stress imposes increasing pressure on ecosystems. Wastewater treatment works (WWTWs) are major stressors in urban environments and are associated with high levels of pollutants that bioaccumulate and elicit stress responses in animals such as bats. Stress responses are linked with increased metabolic rate and may result in energy store depletion. In this study we measured the effects of WWTWs on energy stores and leptin levels in the insectivorous bat, Neoromicia nana. Energy stores including glucose, glycogen, lipids and proteins were measured in the storage tissues (liver and pectoral muscles) and blood of bats. Further, lactic acid was measured in the pectoral muscles to provide an indirect measure of anaerobic respiration and stress. Leptin, the hormone associated with satiation, and hypoxia inducible factor 1α (Hif-1α) were measured in the interscapular brown adipose tissue (iBrAT). Bats caught at WWTWs exhibited significantly higher pectoral glucose and lactic acid concentrations than bats at reference sites, indicating a stress induced increase in glucose demand and increased reliance on gluconeogenesis to fuel this response. However, glycogen, lipid and protein stores were not depleted in WWTW bats. This may be due to their fat-rich diet at WWTW sites. Moreover, this high polyunsaturated fatty acid (PUFA) diet may be responsible for the unexpectedly high leptin levels in WWTW bats. Lactic acid concentrations were elevated in the pectoral muscles of bats at WWTW sites, indicating some degree of oxidative stress although there was no increase in iBrAT Hif-1α levels. These results show that in the face of environmental stresses, N. nana is able to maintain energy stores.

A global empirical typology of anthropogenic drivers of environmental change in deltas.

It is broadly recognized that river delta systems around the world are under threat from a range of anthropogenic activities. These activities occur at the local delta scale, at the regional river and watershed scale, and at the global scale. Tools are needed to support generalization of results from case studies in specific deltas. Here, we present a methodology for quantitatively constructing an empirical typology of anthropogenic change in global deltas. Utilizing a database of environmental change indicators, each associated with increased relative sea-level rise and coastal wetland loss, a clustering analysis of 48 global deltas provides a quantitative assessment of systems experiencing similar or dissimilar sources and degrees of anthropogenic stress. By identifying quantitatively similar systems, we hope to improve the transferability of scientific results across systems, and increase the effectiveness of delta management best practices. Both K-Means and Affinity Propagation clustering algorithms find similar clusters, with relative stability across small changes in K-Means cluster number. High-latitude deltas appear similar, in terms of anthropogenic environmental stress, to several low-population, low-latitude systems, including the Amazon delta, despite substantially different climatic regimes. Highly urbanized deltas in Southeast Asia form a distinct cluster. By providing a quantitative boundary between groups of delta systems, this approach may also be useful for assessing future delta change and sustainability given projected population growth, urbanization, and economic development trends.

Can biotic indicators distinguish between natural and anthropogenic environmental stress in estuaries?

Because estuaries are naturally stressed, due to variations in salinity, organic loadings, sediment stability and oxygen concentrations over both spatial and temporal scales, it is difficult both to set baseline reference conditions and to distinguish between natural and anthropogenic environmental stresses. This contrasts with the situation in marine coastal and offshore locations. A very large benthic macroinvertebrate dataset and matching concentrations for seven toxic heavy metals (i.e. Cr, Ni, Cu, Zn, Cd, Hg and Pb), compiled over three years as part of the UK's National Marine Monitoring Programme (NMMP) for 27 subtidal sites in 16 estuaries and 34 coastal marine sites in the United Kingdom, have been analysed. The results demonstrate that species composition and most benthic biotic indicators (number of taxa, overall density, Shannon–Wiener diversity, Simpson's index and AZTI's Marine Biotic Index [AMBI]) for sites in estuarine and coastal areas were significantly different, reflecting natural differences between these two environments. Shannon–Wiener diversity and AMBI were not significantly correlated either with overall heavy metal contaminant loadings or with individual heavy metal concentrations (‘normalized’ as heavy metal/aluminium ratios) in estuaries. In contrast, average taxonomic distinctness (Δ+) and variation in taxonomic distinctness (Λ+) did not differ significantly between estuarine and coastal environments, i.e. they were unaffected by natural differences between these two environments, but both were significantly correlated with overall heavy metal concentrations. Furthermore, Δ+ was correlated significantly with the Cu, Zn, Cd, Hg and Pb concentrations and Λ+ was correlated significantly with the Cr, Ni, Cu, Cd and Hg concentrations. Thus, one or both of these two taxonomic distinctness indices are significantly correlated with the concentrations for each of these seven heavy metals. These taxonomic distinctness indices are therefore considered appropriate indicators of anthropogenic disturbance in estuaries, as they allow a regional reference condition to be set from which significant departures can then be determined.

KEGG orthology-based annotation of the predicted proteome of Acropora digitifera: ZoophyteBase - an open access and searchable database of a coral genome.

BackgroundContemporary coral reef research has firmly established that a genomic approach is urgently needed to better understand the effects of anthropogenic environmental stress and global climate change on coral holobiont interactions. Here we present KEGG orthology-based annotation of the complete genome sequence of the scleractinian coral Acropora digitifera and provide the first comprehensive view of the genome of a reef-building coral by applying advanced bioinformatics.DescriptionSequences from the KEGG database of protein function were used to construct hidden Markov models. These models were used to search the predicted proteome of A. digitifera to establish complete genomic annotation. The annotated dataset is published in ZoophyteBase, an open access format with different options for searching the data. A particularly useful feature is the ability to use a Google-like search engine that links query words to protein attributes. We present features of the annotation that underpin the molecular structure of key processes of coral physiology that include (1) regulatory proteins of symbiosis, (2) planula and early developmental proteins, (3) neural messengers, receptors and sensory proteins, (4) calcification and Ca2+-signalling proteins, (5) plant-derived proteins, (6) proteins of nitrogen metabolism, (7) DNA repair proteins, (8) stress response proteins, (9) antioxidant and redox-protective proteins, (10) proteins of cellular apoptosis, (11) microbial symbioses and pathogenicity proteins, (12) proteins of viral pathogenicity, (13) toxins and venom, (14) proteins of the chemical defensome and (15) coral epigenetics.ConclusionsWe advocate that providing annotation in an open-access searchable database available to the public domain will give an unprecedented foundation to interrogate the fundamental molecular structure and interactions of coral symbiosis and allow critical questions to be addressed at the genomic level based on combined aspects of evolutionary, developmental, metabolic, and environmental perspectives.

The assessment of environmental pollution along the coast of Beibu Gulf, northern South China Sea: An integrated biomarker approach in the clam Meretrix meretrix

The clam Meretrix meretrix was used as a biomonitor to implement an environmental monitoring program along the coast of Beibu Gulf in October 2011. This program not only analyzed biomarkers including acetylcholinesterase, glutathione peroxidase, glutathione S-transferase, catalase and superoxide dismutase activities, total glutathione content and lipid peroxidation level in M. meretrix but also adopted a multi-biomarker approach – integrated biomarker response (IBR) to assess the environmental quality in this ecosystem. In addition, the metal (Hg, As, Cu, Pb, Zn, Cd and Cr) and polychlorinated biphenyls (PCBs) content in the surface sediment at the study area were also measured. The results showed that IBR index was able to distinguish a space trend between sampling sites with different degrees of anthropogenic environmental stress. Integrated contamination degree were displayed in the form of star plots and compared to IBR plots. There was a visual consistency between the pollution level and IBR variation. Based on the results, it was proved that the IBR method coupled with chemical analysis was quite useful for the assessment of environmental pollution in the coastal system.

Proteomic study of the effects of complex environmental stresses in the livers of goldfish (Carassius auratus) that inhabit Gaobeidian Lake in Beijing, China

Recent advances in proteomics have provided an excellent opportunity to understand biological adaptation under complex environmental stress at the protein level. Gaobeidian Lake, located in Beijing, China, is characterized by complex environmental stresses by serving as both the effluent of a wastewater treatment plant and a coolant of a nearby thermal power plant. Liver is the primary organ of energy metabolism and xenobiotic detoxification. To further our understanding of how organisms that live in Gaobeidian Lake acclimatize themselves to these complex environmental stresses, hepatic protein expression patterns were examined in goldfish Carassius auratus that inhabit the lake. Huairou Reservoir, a drinking water source, was used as a reference site. Twenty four protein spots, which were differently expressed in the two sites, were further digested with trypsin and analyzed by matrix-assisted laser desorption/ionization (MALDI) tandem time of flight mass spectrometry (TOF/TOF). The expression of several energy metabolism and oxidative stress proteins, such as glutathione peroxidase (GPx), ferritin H3, and liver basic fatty acid-binding protein (Lb-FABP) were found to be altered in this stressful environment. In addition to the up-regulation of GPx translation, both the mRNA levels and enzymatic activity of GPx protein were elevated in goldfish living in Gaobeidian Lake. The expression of both peroxisome proliferator activated receptor (PPAR), one of the most important metabolism and stress regulation genes as well as cytochrome P450 1A1 (CYP1A1), a detoxification gene, was also detected by real-time PCR at the two sites. Increased expression levels of both PPAR-beta and CYP1A1 (P < 0.1) were observed in Gaobeidian Lake. Our study provides an integrative view of the expression levels of hepatic proteins and genes in goldfish under complex environmental stress that live in Gaobeidian Lake. Our results showed that anthropogenic environmental stresses in Gaobeidian Lake activated the regulation gene of lipid metabolism PPAR, elevated the lipid metabolism levels, and activated the anti-oxidative adaptation mechanism of organisms in the lake.

Does changing the taxonomical resolution alter the value of soil macroinvertebrates as bioindicators of metal pollution?

Ecological indicators are taxa that are affected by, and indicate effects of, anthropogenic environmental stress or disturbance on ecosystems. There is evidence that some species of soil macrofauna (i.e. diameter >2 mm) constitute valuable biological indicators of certain types of soil perturbations. This study aims to determine which level of taxonomic resolution, (species, family or ecological group) is the best to identify indicator of soil disturbance. Macrofauna were sampled in a set of sites encompassing different land-use systems (e.g. forests, pastures, crops) and different levels of pollution. Indicator taxa were sought using the IndVal index proposed by Dufrêne and Legendre [Dufrêne, M., Legendre, P., 1997. Species assemblages and indicator species: the need for a flexible asymetrical approach. Ecological Monographs 67, 345–366]. This approach is based on a hierarchical typology of sites. The index value changes along the typology and decreases (increases) for generalist (specialist) faunal units (species, families or ecological groups). Of the 327 morphospecies recorded, 19 were significantly associated with a site type or a group of sites (5.8%). Similarly, species were aggregated to form 59 families among which 17 (28.8%) displayed a significant indicator value. Gathering species into 28 broad ecological assemblages led to 14 indicator groups (50%). Beyond the simple proportion of units having significant association with a given level of the site typology, the proportion of specialist and generalist groups changed dramatically when the level of taxonomic resolution was altered. At the species level 84% of the indicator units were specialist, whereas this proportion decreased to 70 and 43% when families and ecological groups were considered. Because specialist groups are the most interesting type of indicators either in terms of conservation or for management purposes we come to the conclusion that the species level is the most accurate taxonomic level in bioindication studies although it requires a high amount of labour and operator knowledge and is time-consuming.

Decreased resistance of eastern oysters ( Crassostrea virginica) to a protozoan pathogen ( Perkinsus marinus) after sublethal exposure to tributyltin oxide

Anthropogenic environmental stress is a likely contributor to outbreaks of disease due to immunosuppression or increased host vulnerability. Estuarine organisms are exposed to variable concentrations of marine antifouling agents, such as tributyltin (TBT), with higher exposures existing near ports and marinas. Eastern oysters ( Crassostrea virginica), inhabiting the northern Gulf of Mexico and the Atlantic coast of North America, are susceptible to a protozoan pathogen, Perkinsus marinus, which has devastated oyster populations and depleted oyster fisheries throughout its range. This study examined the effects of exposure to environmental levels of TBT on susceptibility and survival of oysters when subsequently challenged with P. marinus. Oysters were exposed to TBT (0, 30 and 80 ng/L) in flow-through aquaria for 9 weeks, then moved to static aquaria, where they were challenged with parasites and monitored for an additional 8 weeks for mortality and disease. Results indicated increased infection intensity and oyster mortality in the TBT-exposed treatments relative to unexposed controls. It is hypothesized that TBT exacerbates the infectious disease process and that exposed oysters succumb at lower levels of infection.

Stress proteins in aquatic organisms: an environmental perspective.

The cellular stress response protects organisms from damage resulting from exposure to a wide variety of stressors, including elevated temperatures, ultraviolet (UV) light, trace metals, and xenobiotics. The stress response entails the rapid synthesis of a suite of proteins referred to as stress proteins, or heat-shock proteins, upon exposure to adverse environmental conditions. These proteins are highly conserved and have been found in organisms as diverse as bacteria, molluscs, and humans. In this review, we discuss the stress response in aquatic organisms from an environmental perspective. Our current understanding of the cellular functions of stress proteins is examined within the context of their role in repair and protection from environmentally induced damage, acquired tolerance, and environmental adaptation. The tissue specificity of the response and its significance relative to target organ toxicity also are addressed. In addition, the usefulness of using the stress response as a diagnostic in environmental toxicology is evaluated. From the studies discussed in this review, it is apparent that stress proteins are involved in organismal adaptation to both natural and anthropogenic environmental stress, and that further research using this focus will make important contributions to both environmental physiology and ecotoxicology.

Efficient sequential sampling strategies for environmental monitoring

Assessments of resources at risk to anthropogenic pollution require extensive environmental monitoring. In addition, such assessments are required to have a long‐term monitoring component in order to evaluate not only the status but also the trend of the resources at risk to ecological stresses. There is a need to identify statistical methodologies that would provide effective and cost‐saving environmental monitoring designs, since such monitoring surveys are very expensive. In this paper the purely sequential, accelerated sequential, and three‐stage procedures are evaluated as effective fixed‐precision sampling procedures for environmental monitoring. Current monitoring designs utilize a sampling methodology where each resource is assigned a population inclusion probability, with the intent of describing the distribution of the whole population of resources at risk to anthropogenic environmental stresses. This study assumes that existing designs accurately describe the population distribution. A simultaneous fixed‐precision estimation procedure is developed as an efficient method of estimating practically relevant percentiles of the cumulative distribution function, using water quality data from the Eastern Lake Survey as a lake population distribution. Accelerated sequential and three‐stage procedures are shown to be better alternatives to the purely sequential procedure, requiring fewer sampling operations without any substantial loss of efficiency. Depending upon the precision required, all procedures showed potential reductions in sample size by as much as 60%. These types of designs for environmental monitoring are expected to be advantageous in national monitoring efforts directed toward the assessment of the status and trends of various ecological indicators.