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1.
Environmental exposure to arsenic (As) in the Kutahya region of the western Anatolia, Turkey has been reported to cause various
types of arsenic-associated skin disorders (Dogan, Dogan, Celebi, & Baris, 2005). A geological and mineralogical study was conducted to find the sources and distribution of the As. Geogenic (background)
levels were measured in samples collected from various sources in the Gediz, Simav, Tavsanli, Emet, Yoncali, Yenicekoy, and
Muratdagi areas of the Kutahya region. Based on this analysis, we determined that natural sources are a domineering factor
affecting the distribution of As, which was found: (1) mainly in evaporitic minerals, including colemanite (269–3900 ppm)
and gypsum (11–99,999 ppm), but also in alunite (7–10 ppm) and chert (54–219 ppm); (2) in secondary epithermal gypsum, which
has a high concentration of As in the form of realgar and orpiment along fracture zones of Mesozoic and Cenozoic carbonate
aquifers; (3) in rocks, including limestone/dolomite (3–699 ppm) and travertine (5–4736 ppm), which are relatively more enriched
in As than volcanics (2–14 ppm), probably because of secondary enrichment through hydrological systems; (4) in coal (1.9–46.5 ppm)
in the sedimentary successions of the Tertiary basins; (5) in thermal waters, where As is unevenly distributed at concentrations
varying from 0.0–0.9 mg/l. The highest As concentrations in thermal water (Gediz and Simav) correlate to the higher pH (7–9.3)
and T (60–83°C) conditions and to the type of water (Na–HCO3–SO4 with high concentration of Ca, Mg, K, SiO2, and Cl in the water). Changes in pH can be related to some redox reactions, such as the cation exchange reactions driving
the dissolution of carbonates and silicates. Fe-oxidation, high pH values (7–9.3), presence of other trace metals (Ni, Co,
Pb, Zn, Al), increased salinity (Na, Cl), high B, Li, F, and SiO, high Fe, SO4 (magnetite, specularite-hematite, gypsum), and graphite, and the presence of U, Fe, Cu, Pb, Zn, and B, especially in the
Emet, Gediz, and Simav areas, are the typical indicators for the geothermally affected water with high As content. A sixth
source of As in this region is the ground (0.0–10.7 mg/l) and the surface waters (0.0022–0.01 mg/l), which are controlled
by water–rock interaction, fracture system, and mixing/dilution of thermal waters. The high As concentration in groundwater
corresponds to the areas where pathological changes are greatest in the habitants. Arsenic in ground water also effects ecology.
For example, only Juriperus oxycedrus and J. varioxycedrus types of vegetation are observed in locations with the highest concentration of As in the region. Branches and roots of these
plants are enriched in As. 相似文献
2.
Xinyi Hu Ting Yang Chen Liu Jun Jin Bingli Gao Xuejun Wang Min Qi Baokai Wei Yuyu Zhan Tan Chen Hongtao Wang Yanting Liu Dongrui Bai Zhu Rao Nan Zhan 《Frontiers of Environmental Science & Engineering》2020,14(4):66
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The reproduction of Crepidula fornicata was studied in the Bay of Brest in order to characterise the first step of the reproductive cycle of this invasive species. The survey was carried out from 2000 to 2003 and different parameters were measured, namely, the percentage of the different sexual stages, the straight length of the shell and the percentage of brooding females using a survey of the embryonic development and the fecundity. The juvenile frequency increases generally from mid-June or mid-August, depending on the year. In 2001 and 2003, a first peak was observed as early as May, but it was followed by a rapid disappearance of the individuals. The sex-ratio female/male increased from 0.22 to 0.46 between 2001 and 2003. The sex change between intermediates and females took place mainly in summer and was well marked in 2001 and 2003. The survey of the embryonic development in the egg capsules brooded by the females provided an annual phenology of the laying and hatching processes. The laying period extends from February to September with three to four major periods of egg-laying per year and corresponding hatching periods about 1 month later. Each female lays two to four times per year on average. The first egg-laying concerned fewer females than subsequent ones, except in 2003, and exhibited a higher fecundity. The annual mean of the number of eggs for each stage was not significantly different, thus indicating no significant mortality rate during embryonic development. For the C. fornicata population in the Bay of Brest, several reproductive characteristics tend to highlight its invasive capacity: (1) a long reproductive period, (2) reproduction in a ‘multi-trials’ process equivalent to a spreading out of the risks and (3) a relatively high fecundity. 相似文献
6.
Andrew D. Irving David Balata Francesco Colosio Guillaume A. Ferrando Laura Airoldi 《Marine Biology》2009,156(6):1223-1231
Recruitment is essential for the maintenance of populations, but far more is typically known about the more easily-observed
adult stages than their smaller, often microscopic early life-history counterparts. This discrepancy can be particularly problematic
for populations of foundation species that create biogenic habitat for a multitude of other taxa, but are themselves prime
candidates for exploitation, fragmentation, and loss, and therefore become the focus of restoration efforts partly or fully
dependent on recruitment. The purpose of this study was to improve ecological understanding for early life-history stages
of the habitat-forming marine alga Cystoseira barbata (Stackhouse) C. Agardh (Fucales: Sargassaceae), member of a genus that has experienced considerable fragmentation and population
decline on European coasts. Using experimental manipulations of water temperature, light intensity, and sediment accumulation,
we observed that sediment virtually precluded recruitment of C. barbata, and greatly impacted the survival of recently settled germlings (up to ~83% mortality). Stronger intensities of light facilitated
the growth of germlings, including the capacity for ~50% of them to outgrow detrimental sediment and survive. Temperature
(10 vs. 16°C) had no effect on early recruitment, survival, or growth. This information helps to identify likely causes and
locations of recruitment failure, and by extension, the conditions needed (either naturally or through human intervention)
to facilitate recruitment and possible habitat restoration. Ultimately, this knowledge can increase our capacity to predict
population persistence and the likely success of restoration efforts. 相似文献
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J. R. Weinberg 《Marine Biology》1998,130(4):621-630
Spisula solidissima (Dillwyn, 1817) is a large, suspension-feeding bivalve, whose range extends from Nova Scotia to South Carolina. This species
is harvested commercially. Shell length and age data were collected for this species from 1980 to 1994 during surveys of population
size and structure. These data were used to examine the relationship between the growth rate of S.␣solidissima and intraspecific density. The null hypothesis was that density (represented by number of individuals per tow) would have
no effect on rate of growth. A negative relationship would support the alternative hypothesis, that intraspecific competition
had taken place. This analysis focused on the surfclam population offshore from the Delmarva Peninsula, USA because: (1) a
major recruitment event occurred in 1977, (2) clam fishermen had reported “stunted” surfclams in that area, (3) a wide range
of local densities were available to examine, and (4) the existence of a closed area within the study area set up an interesting
contrast with areas left open to harvesting. Maps of surfclam abundance across the Delmarva region demonstrate that areas
of highest density have generally remained in the same location through time. The results suggested that intraspecific competition
has been important in structuring this population. Based on data from 1980 to 1992, shell length was significantly reduced
at high density, and a significant interaction between age and density was observed. Growth modeling indicated decreased asymptotic
lengths and growth rates with increasing density. In nine out of ten pairwise randomization tests, fitted von Bertalanffy
growth curves, representing different densities, were significantly different from each other. High densities of clams have
persisted in the area that was closed to harvesting for 11 years (1980 to 1991). In 1994, length at age was significantly
less in this closed area compared to that in the surrounding area. This effect was apparent in clams from 3 to 17 years of
age, and most pronounced in the cohort that recruited to the Delmarva region in high numbers in 1977. Lower growth rates within
the closed area have management implications for the optimal duration of closures.
Received: 16 May 1997 / Accepted: 7 October 1997 相似文献
9.
Carrie E. Givens Karen G. Burnett Louis E. Burnett James T. Hollibaugh 《Marine Biology》2013,160(11):2841-2851
The Atlantic blue crab Callinectes sapidus is an important fisheries resource that is subject to mortality and morbidity from hemolymph infections. We used culture-independent methods based on the analysis of 16S rRNA genes to characterize and quantify the microflora from the carapace, gut, and hemolymph of C. sapidus with the goals of (1) characterizing the C. sapidus microbial assemblage and (2) identifying the reservoirs of potential pathogens associated with the crab. We found that the carapace, gut and hemolymph microflora have a core Proteobacteria community with contributions from other phyla including Bacteroidetes, Firmicutes, Spirochetes, and Tenericutes. Within this Proteobacteria core, γ-Proteobacteria, including the members of the Vibrionaceae that are closely related to potential pathogens, dominate. Bacteria closely related to hemolymph pathogens were found on the carapace, supporting the hypothesis that punctures, molting damage, or broken dactyls may be routes for hemolymph infections. These results provide some of the first data on the blue crab microbial assemblage obtained with culture-independent techniques and offer insights into the routes of infection and potential bacterial pathogens associated with blue crabs. 相似文献
10.
Heavy metals pollution in aquatic environments is a major problem contributing to human health issues. The study of these pollutants through bioindicators such as the oyster Crassostrea iredalei is important for (1) determining the levels and sources and (2) regulating the quantity of pollutants. The concentrations of cadmium (Cd), manganese (Mn), copper (Cu), zinc (Zn), and lead (Pb) in tissues of C. iredalei, sediment and surrounding water was measured, and data was analyzed to determine the relationship between sampling periods and between oyster tissue, sediment, and water. The highest concentration of metals in oyster tissue was Zn, followed by Cu, Mn, Cd, and Pb. Concentrations of Cd, Cu, and Zn exceeded the maximum level allowed according to the Malaysian Food Act of 1983, which is equivalent to the WHO recommended levels of heavy metals in organisms used for consumption. The highest metal concentration in sediment was Mn followed by Zn, Pb, Cu, and Cd. Concentrations of heavy metals in surrounding water were Zn, Pb, Cu, Mn, and Cd. There was no correlation between metal concentration in oyster tissue and in sediment for all five metals. 相似文献
11.
Logging, Conifers, and the Conservation of Crossbills 总被引:1,自引:0,他引:1
Craig W. Benkman 《Conservation biology》1993,7(3):473-479
A survey of the forestry literature shows that as the age and area of coniferous forests decline, decreased conifer seed production and increased frequencies of cone failures can be expected. This would, in turn, cause declines in crossbills ( Loxia ), which specialize on the seeds held in conifer cones. In western North America, at least five different species of Red Crossbills ( L. curvirostra ) have recently been distinguished (Groth 1990); each specializes on a different species or even a single variety of conifer (Benkman 1993). Measures for conserving this diversity of crossbills include protecting mature and old-growth stands, and increasing rotation ages throughout the range of each of the required conifers. These recommendations are not unique to crossbills, but rather the loss of crossbill diversity is another reason to employ such measures. 相似文献
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Blooms of the toxic dinoflagellate Heterocapsa circularisquama cause massive bivalve kills in Japan. Mariculture of the Japanese pearl oyster, Pinctada fucata martensii, is the industry most affected by these blooms, especially in Ago Bay, Mie Prefecture, where they are frequent, cause mass mortality of oysters, and overlap with their spawning season. The goal of this August 2009 study was to assess the effects of a toxic strain of H. circularisquama isolated from Ago Bay on gametes, fertilization, and embryo development of pearl oysters. Spermatozoa, eggs, spermatozoa and eggs, and fertilized eggs of pearl oysters from Ago Bay were exposed to H. circularisquama at cell densities reported during the bloom (10–104 cells mL?1) for different periods of time. The concentration of H. circularisquama, exposure duration, and their interactions all had significant effects on gamete quality, fertilization, and embryo development. The motility and swimming velocity of spermatozoa, egg viability, fertilization, and embryo development rate were significantly reduced in all concentrations, with a cell density of 10 cells mL?1 determined to be the critical density of H. circularisquama for deleterious effects. This is the first evidence of inimical effects of an HAB species on bivalve spermatozoa upon direct exposure. Further field and laboratory studies are required to investigate the potential effects of H. circularisquama blooms on the reproduction and recruitment of Japanese pearl oysters and other bivalves. 相似文献
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John Cairns Jr. 《国际发展与全球生态学杂志》2013,20(1):43-48
SUMMARY The intricate and complex relationships between transhumant pastoralists, livestock and environment at the high altitudes of Indian Central Himalaya has started to break down at an alarming rate. Some of the important factors attributed to this are depletion of grazing resources, commercialization of the rural economy, and integration of these communities with the mainstream of development through education and employment. Traditionally these livestock were assigned different roles in society depending upon their economic benefit and utility. The roles which once depended upon attitude to various risks, such as environmental, social and economic, have lost their significance due to changing of the production process. This paper gives an overview of the various types of roles the livestock played in the transhumant society, and how they are being replaced by the developmental process in the region, and whether the changes are sustainable for such remote regions in a developing country. 相似文献
17.
Martin F. Quaas Daan van Soest Stefan Baumgärtner 《Journal of Environmental Economics and Management》2013
We study how society's preferences affect the resilience of economies that depend on more than one type of natural resource. In particular, we analyze whether the degree of complementarity of natural resources in consumer preferences may give rise to multiple steady states and path dependence even when resources are managed optimally. We find that, for a given social discount rate, society tends to be less willing to buffer exogenous shocks if resource good are complements in consumption than if they are substitutes. The stronger the complementarity between the various types of natural resources, the less resilient the economy is, and even more so the higher is the social discount rate. 相似文献
18.
Byron K. Williams 《Environmental and Ecological Statistics》2001,8(3):269-288
Wildlife management is limited by uncontrolled and often unrecognized environmental variation, by limited capabilities to observe and control animal populations, and by a lack of understanding about the biological processes driving population dynamics. In this paper I describe a comprehensive framework for management that includes multiple models and likelihood values to account for structural uncertainty, along with stochastic factors to account for environmental variation, random sampling, and partial controllability. Adaptive optimization is developed in terms of the optimal control of incompletely understood populations, with the expected value of perfect information measuring the potential for improving control through learning. The framework for optimal adaptive control is generalized by including partial observability and non-adaptive, sample-based updating of model likelihoods. Passive adaptive management is derived as a special case of constrained adaptive optimization, representing a potentially efficient suboptimal alternative that nonetheless accounts for structural uncertainty. 相似文献
19.
Harshinie Karunarathna 《Journal of Coastal Conservation》2011,15(4):499-507
The long-term morphodynamic response of the Clyde Estuary to any possible change in environmental forcing associated with
global climate change and human interference is examined here using a model based on a systems approach. The model, which
uses Boolean Algebra as its formal mathematical language, provides a qualitative insight into the long term morphodynamic
behaviour of the estuarine system, at this level without the need for detailed and quantitative hydrodynamic and morphodynamic
process knowledge or extensive data resources. The model predictions suggest that the long-term morphological changes in the
Clyde Estuary largely depend on the fluvial flow of the River Clyde. Salt marshes in the upper reaches of the estuary were
found to be the most vulnerable morphological feature of the estuary. In the event of increased river flow in the future,
a likely situation according to climate change scenarios, saltmarshes will deplete or disappear altogether, irrespective of
the sediment influx into the estuary. Changes to waves and tides will also contribute to the evolution by taking the estuary
through significantly different intermediate morphological states whilst evolving towards a stable end state. 相似文献
20.
Abstract: The global amphibian crisis has resulted in renewed interest in captive breeding as a conservation tool for amphibians. Although captive breeding and reintroduction are controversial management actions, amphibians possess a number of attributes that make them potentially good models for such programs. We reviewed the extent and effectiveness of captive breeding and reintroduction programs for amphibians through an analysis of data from the Global Amphibian Assessment and other sources. Most captive breeding and reintroduction programs for amphibians have focused on threatened species from industrialized countries with relatively low amphibian diversity. Out of 110 species in such programs, 52 were in programs with no plans for reintroduction that had conservation research or conservation education as their main purpose. A further 39 species were in programs that entailed captive breeding and reintroduction or combined captive breeding with relocations of wild animals. Nineteen species were in programs with relocations of wild animals only. Eighteen out of 58 reintroduced species have subsequently bred successfully in the wild, and 13 of these species have established self‐sustaining populations. As with threatened amphibians generally, amphibians in captive breeding or reintroduction programs face multiple threats, with habitat loss being the most important. Nevertheless, only 18 out of 58 reintroduced species faced threats that are all potentially reversible. When selecting species for captive programs, dilemmas may emerge between choosing species that have a good chance of surviving after reintroduction because their threats are reversible and those that are doomed to extinction in the wild as a result of irreversible threats. Captive breeding and reintroduction programs for amphibians require long‐term commitments to ensure success, and different management strategies may be needed for species earmarked for reintroduction and species used for conservation research and education. 相似文献