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421.
Joseline Molozzi Maria João Feio Fuensanta Salas João Carlos Marques Marcos Callisto 《Environmental monitoring and assessment》2013,185(8):6591-6606
The Reference Condition Approach (RCA) is now widely adopted as a basis for the evaluation of the ecological quality of water bodies. In accordance with the RCA, the integrity of communities found in a given location should be analyzed according to their deviation from the communities that would be expected in the absence of anthropogenic disturbances. The RCA was used here with the aim of defining the Maximum Ecological Potential (MEP) of tropical reservoirs located in the hydrographical basin of the Paraopeba River in the state of Minas Gerais, Brazil. Among the reservoirs, Serra Azul is used as a water supply and is located in a core area of environmental protection where tourism is not allowed and the native vegetation is conserved. The benthic macroinvertebrate communities at 90 sites located in three reservoirs were analyzed and sampled every 3 months over 2 years. The temporal patterns of the communities in the three reservoirs were analyzed (2nd-STAGE MDS and ANOSIM) and were not significantly related to seasonal fluctuations in temperature and precipitation. Twenty-eight sites belonging to the Serra Azul reservoir were selected to define the MEP of these reservoirs because these sites had the lowest human disturbance levels. The macroinvertebrate taxa present in the selected MEP sites are similar to those of natural lakes and different from the communities of disturbed sites. The biological classification of these sites revealed two groups with distinct macroinvertebrate communities. This distinction was related to climatic variables, bottom substrate type, the presence of gravel/boulders, coarse sand, silt, clay or muck, depth, and the shoreline substrate zone. These two subsets of biological communities and respective environmental conditions can serve as a basis for the future implementation of ecological quality monitoring programs for tropical reservoirs in the study area. This approach can also, however, be implemented in other geographic areas with artificial or heavily modified water bodies. 相似文献
422.
Victoria Ochoa Carlos Barata M. Carmen Riva 《Environmental monitoring and assessment》2013,185(8):6783-6792
The aim of this study was to determine heavy metal content (As, Cd, Cu, Hg, Cd, Pb, and Zn) in oysters transplanted in Ebro Delta bays (Alfacs and Fangar) where oysters are traditionally cultured for human consumption. Metal body burdens were monitored weekly during the period of maximal agriculture activity from May to June in 2008 and 2009. Results indicate that regardless of the high levels of metals reported in biota living in Ebro River, metal levels in oysters from both bays were similar to those found in unpolluted areas and far below the maximum limits of tolerance recommended by the European Commission. Nevertheless, metal accumulation patterns in oysters differentiate two sources of pollution: one coming from agriculture activities within the Ebro’s delta for As, Cd, Cu, and Zn and other coming from Ebro River probably related to industrial activities upstream (Hg, Pb) or to lead shot pellets form hunting activities (Pb). Reported results, thus, are in concern with previous studies and indicate that metallic pollutants do not affect oysters cultures in Ebro Delta associated bays. 相似文献
423.
Astray G Rodríguez-Rajo FJ Ferreiro-Lage JA Fernández-González M Jato V Mejuto JC 《Journal of environmental monitoring : JEM》2010,12(11):2145-2152
The monitoring of atmospheric Alternaria spores is of major importance due to their adverse effects on crops and their role as human allergens. Most species act as plant pathogens, prompting considerable economic losses worldwide on important crops such as potato, tomato or wheat. Fungal spores can also have serious detrimental effects on human health, triggering respiratory diseases and allergenic processes. The aim of this study was not only to examine the relationship between the atmospheric Alternaria spore content and the prevailing meteorological parameters, but also to predict the atmospheric Alternaria spore content in the Northwest Spain using a novel data analysis technique, ANNs (Artificial Neural Networks). A Hirst-type LANZONI VPPS 2000 volumetric 7-day recording sampler was used to collect the airborne spores from 1997 to 2008. Neural networks provided us with a good tool for forecasting Alternaria airborne spore concentration, and thus could help the automation of the prediction system in the aerobiological information diffusion to the population suffering from allergic problems or the prevention of considerable economic worldwide losses on important crops. Our proposed model would be applied to different geographical areas; nevertheless, the adjustment of the model, by using the available and adequate variables, would be realised in each case. 相似文献
424.
Ramos Marcio Antonio Gomes Bueno de Oliveira Eduardo Schneider Pião Antonio Carlos Simões Nalin de Oliveira Leite Dilza Aparecida de Franceschi de Angelis Dejanira 《Environmental monitoring and assessment》2016,188(5):1-14
Environmental Monitoring and Assessment - Due to the concern with the quality of hydric resources, the monitoring is essential to evaluate and identify the anthropogenic and environmental... 相似文献
425.
Francisco Encina-Montoya Rolando Vega-Aguayo Oscar Díaz Carlos Esse Jorge Nimptsch Andrés Muñoz-Pedreros 《Environmental monitoring and assessment》2017,189(11):584
The suitability of Mazzaella laminarioides and Sarcothalia crispata as heavy metal biomonitors of Cd, Cu, Hg, Pb, and Zn was assessed by comparing bioaccumulation of these elements in different life stages and frond sizes in samples from three locations, San Vicente Bay (industrial area), Coliumo, and Quidico (the latter as a reference station), where different degrees of heavy metal pollution are recorded. Bioaccumulation and bioconcentration factors of Cd, Cu, Hg, Pb, and Zn were evaluated. The two macroalgae species showed similar patterns, with higher values of Cu, Hg, Pb, and Zn in polluted areas. M. laminarioides bioaccumulated higher concentrations of all metals assessed than S. crispata, independent of life stage and frond size. The results also showed significantly higher Cu, Hg, Pb, and Zn concentrations (p < 0.05) in water samples from San Vicente Bay than those measured in Coliumo and Quidico. Concentrations of Cd, Hg, Pb, and Zn in San Vicente Bay and Cd, Hg, and Pb in Coliumo and Quidico exceed the mean values considered to represent natural concentrations (Cu = 3.00 μg L?1; Zn = 5.00 μg L?1; Pb = 0.03 μg L?1; Cd = 0.05 μg L?1; Hg = 0.05 μg L?1); however, the concentrations recorded do not cause negative effects on the growth and survival of macroalgae. The assessment of heavy metals bioaccumulated in M. laminarioides and S. crispata, particularly Hg, Pb, and Zn, offers a reliable approach for pollution assessment in rocky intertidal environments. Cu and Cd concentrations in seawater samples from San Vicente and Coliumo Bays were significantly higher than in those from Quidico (p value < 0.05); no significant differences in Cd concentrations were observed between San Vicente and Coliumo Bays (p < 0.05). Exceptionally, Cd is bioaccumulated at high levels independent of its availability in the water, thus reaching high concentrations in control areas. High concentrations of metals like Cu and Zn may limit or inhibit Cd uptake in macroalgae, since the transport channels are saturated by some metals, reducing the accumulation of others. These macroalgae species offer good potential for the development of suitable heavy metal pollution survey tools in rocky intertidal environments. 相似文献
426.
This study presented the monitoring and quantification of streambed sedimentation and scour in a stream with dynamically changing streambed based on measured phase and amplitude of the diurnal signal of sediment temperature time series. With the applied method, changes in streambed elevation were estimated on a sub-daily scale with 2-h intervals without continuous maintenance of the measurement system, thus making both high temporal resolution and long-term monitoring of streambed elevations possible. Estimates of streambed elevation showed that during base flow conditions streambed elevation fluctuates by 2–3 cm. Following high stream stages, scouring of 2–5 cm can be observed even at areas with low stream flow and weak currents. Our results demonstrate that weather variability can induce significant changes in the stream water and consequently sediment temperatures influencing the diurnal temperature signal in such an extent that the sediment thickness between paired temperature sensors were overestimated by up to 8 cm. These observations have significant consequences on the design of vertical sensor spacing in high-flux environments and in climates with reduced diurnal variations in air temperature. 相似文献
427.
Ana?FaríasEmail author Iker?Uriarte Jorge?Hernández Soledad?Pino Cristina?Pascual Claudia?Caamal Pedro?Domíngues Carlos?Rosas 《Marine Biology》2009,156(8):1547-1558
The scaling of metabolic rates with body mass is one of the best known and most studied characteristics of aquatic animals.
Herein, we studied how size is related to oxygen consumption, ammonia excretion, and ingestion rates in tropical (Octopus maya) and cold-water (Enteroctopus megalocyathus) cephalopod species in an attempt to understand how size affects their metabolism. We also looked at how cephalopod metabolisms
are modulated by temperature by constructing the relationship between metabolism and temperature for some benthic octopod
species. Finally, we estimated the energy balance for O. maya and E. megalocyathus in order to validate the use of this information for aquaculture or fisheries management. In both species, oxygen consumption
and ammonia excretion increased allometrically with increasing body weight (BW) expressed as Y = aBW
b
. For oxygen consumption, b was 0.71 and 0.69 for E. megalocyathus and O. maya, respectively, and for ammonia excretion it was 0.37 and 0.43. Both species had low O/N ratios, indicating an apparent dependence
on protein energy. The mean ingestion rates for E. megalocyathus (3.1 ± 0.2% its BW day−1) and O. maya (2.9 ± 0.5% its BW day−1) indicate that voracity, which is characteristic of cephalopods, could be independent of species. The scope for growth (P = I − (H + U + R) estimated for E. megalocyathus was 28% higher than that observed in O. maya (320 vs. 249 kJ day−1 kg−1). Thus, cold-water cephalopod species could be more efficient than tropical species. The protein and respiratory metabolisms
of O. maya, E. megalocyathus, and other octopod species are directly dependent on temperature. Our results offer complementary evidence that, as Clarke
(2004) stated, the metabolic response (R and U) cannot be determined mechanistically by temperature, as previously proposed (Gillooly et al. 2002). 相似文献
428.
The optimal pricing of pollution when enforcement is costly 总被引:3,自引:0,他引:3
John K. Stranlund Carlos A. Chvez Mauricio G. Villena 《Journal of Environmental Economics and Management》2009,58(2):183-191
We consider the pricing of a uniformly mixed pollutant with a model of optimal, possibly firm-specific, emissions taxes and their enforcement under incomplete information about firms’ abatement costs, enforcement costs, and pollution damage. We argue that optimality requires an enforcement strategy that induces full compliance by every firm, except possibly when a regulator can base the probabilities of detecting individual violations on observable correlates of violators’ actual emissions. Moreover, optimality requires discriminatory taxes, except when a regulator is unable to use observable firm-level characteristics to gain some information about the variation in firms’ abatement costs or monitoring costs. 相似文献
429.
Alvar Carranza Omar Defeo Juan Carlos Castilla Thiago Fernando L. V. B. Rangel 《Marine Biology》2009,156(9):1917-1928
We tested to what extent mean sea surface temperature, geometric constraints in range size frequency distributions (the mid-domain
effect) and geographical coastline distance to the equator are related to species richness of coastal Mytilidae and Ostreidae
in the Pacific and Atlantic coasts of South America (excluding islands). The location and magnitude of the peaks in species
richness, as well as the shape of the pattern, varied between oceans. Results were not biased by spatial autocorrelation,
although strong multicollinearity among predictor variables was detected. However, these regional-extent regression models
suggest differences in the causal factors that explain richness gradients of studied bivalves in South American coasts, most
likely related to historical events such as the Southeastern Pacific Pleistocene mass extinction of bivalves. Our results
reinforced the conclusion that there is no single best explanatory cause for the latitudinal gradient in species richness
and showed that the correlative approach is not useful when predictor variables are strongly correlated. 相似文献
430.
Carlos Ruiz Sebastián Kerry J. Sink Timothy R. McClanahan Donald A. Cowan 《Marine Biology》2009,156(10):2049-2062
The high-latitude coral communities of southern Africa suffered minimal impacts during past mass bleaching events. Recent
reports indicate an increase in bleaching frequency during the last decade, yet the actual levels of thermal stress and contributing
factors in these bleaching events, and the degree of acclimatisation or adaptation on these reefs are poorly understood. During
the 2005 warm-water anomaly in the southern Indian Ocean we conducted bleaching surveys and collected samples for genotyping
of the algal symbiont communities at 21 sites in southern Mozambique and South Africa. Coral bleaching reached unprecedented
levels and was negatively correlated with both latitude and water depths. Stylophora pistillata and Montipora were the most susceptible taxa, whereas three common branching corals had significantly different bleaching responses (Stylophora > Acropora > Pocillopora). Temperature records indicated that localised strong upwelling events coupled with persistent above-average seawater temperatures
may result in accumulated thermal stress leading to bleaching. Symbiodinium in 139 scleractinian corals belonged almost exclusively to clade C, with clade D symbionts present in only 3% of the colonies. Two atypical C subclades were present in Stylophora and Pocillopora colonies and these were more abundant in shallow than deeper sites. Taxon-specific differences in bleaching responses were
unrelated to different clades of algal symbionts and suggest that Symbiodinium C subtypes with diverse thermal tolerance, coupled with acclimatisation and morphology of the host colony influence the bleaching
response. Additionally, the predominance of putatively thermal-sensitive Symbiodinium in southern African corals may reflect a limited experience of bleaching and emphasises the vulnerability of these reefs
to moderate levels of thermal stress. 相似文献