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991.
The assessment of relevant spatial scales at which ecological processes occur is of special importance for a thorough understanding
of ecosystem functioning. In coastal ecosystems, the variability of trophic interactions has been studied at different spatial
scales, but never at scales from centimetres to metres. In the present study, we investigated the link between habitat structure
and small-scale variability of food web functioning on intertidal boulder field ecosystems. Two microhabitats, boulder-top
and boulder-bottom, were considered, and the trophic ecology of invertebrate consumers was studied using stable isotope tracers.
We found for two of the main suspension feeders of northern Atlantic rocky shores (the sponges Halichondria panicea and Hymeniacidon sanguinea) consistent 15N enrichment for individuals sampled under boulders, suggesting that these consumers relied on different trophic resource
according to the microhabitat inhabited, at a centimetre scale. The high δ15N signatures found underneath boulders suggested higher use of highly decomposed organic matter in this microhabitat. The
isotopic difference between the two microhabitats decreased in higher trophic level consumers, which likely foraged at a spatial
scale including both microhabitats. Finally, our results reveal that in highly heterogeneous habitats such as boulder fields,
trophic interactions are likely to vary strongly in space, which should be considered in future researches. The link between
habitat physical structure and food web variability might also contribute to the high biological diversity characterizing
heterogeneous ecosystems. 相似文献
992.
Mateus Georgenes Magarotto Monica Ferreira da Costa José António Tenedório Carlos Pereira Silva 《Journal of Coastal Conservation》2016,20(1):31-42
Coastal zones around the world have experienced urban growth in the last 50 years. This landscape change brings new aspects for those zones and the environment. Real estate speculation is a decisive factor that changes landscape, with urban growth that occurs both in the extent and volume of construction. Boa Viagem (BV) beach at Recife, Northeast Brazil was just a sand bar covered by an Atlantic Forest until middle of the 1800s. Today, it has turned into a busy area of the city where residences, services and commerce co-exist in a densely packed arrangement. This work demonstrates and analyses vertical growth in BV and urban changes from 1961 to 2011. It was developed using digital image processing and visual analysis of satellite imagery and aerial photos. A GIS was created using SPRING and ArcScene, to calculate variations in area and volume creating a Volumetric Index (VI). The Minimal Mapping Area was used in sixteen census tract as samples of the area. Occupation and vertical growth were especially accentuated from 1981 to 1996 with the peak at 2011. Increases in vertical growth from shore to inland are evident in all parts of the district. This finding was confirmed by three-dimensional GIS representations of the study area and the VI during the period of this work, showing the potential of 3D GIS models for studying dense urbanization areas in coastal zones. 相似文献
993.
Impact of socioeconomic development on ecosystem services and its conservation strategies: a case study of Shandong Province,China 总被引:1,自引:0,他引:1
Ecosystems and their components provide a lot of benefits for the welfare of human beings. Coupled with increasing socioeconomic
development, most of the rapidly developing and transitional countries and regions have been experiencing dramatic land use
changes. This has resulted in a large amount of forestland, grassland, and wetland being occupied as residential and industrial
land or reclaimed for arable land, which in turn results in a sharp deterioration of ecosystem services around the world.
Shandong Province, an economically powerful province of China, was chosen as a case study in order to capture the impact of
socioeconomic development on ecosystem services. By way of the study, land uses and their changes were categorized between
1980 and 2006, and the ecosystem services capital and changes of 111 counties of Shandong Province in different phases were
evaluated, as well as the total ecosystem services capital, followed by the zoning of ecosystem services function region of
Shandong Province. We found that the counties in mountainous areas and wetlands, where generally the prefectural-level cities
are located with a rapid socioeconomic development, experienced a successive deterioration of ecosystem services especially
during the 2000s. Finally, three conservation strategies for managing and improving ecosystem services were proposed and discussed
with the aim of achieving coordinate and sustainable development of the socioeconomy, environment, and ecosystems not only
in Shandong Province but also in other provinces of China, as well as in other developing and transitional countries and regions. 相似文献
994.
Fluoride occurrence and assessment of exposure dose of fluoride in shallow aquifers of Makur, Unnao district Uttar Pradesh, India 总被引:1,自引:0,他引:1
The water samples from the shallow aquifers of Makur, Unnao district, Uttar Pradesh, was analyzed for fluoride content (F( - )) and other water quality parameters such as pH, EC, CO(3) (2-), HCO(3) (-), Cl( - ), Na( + ), Ca(2 + ), Mg(2 + ) and RSC. It was found that the F( - ) concentration of water varied between 1.05 to 13.9 mgl( - 1) which exceeded the maximum desirable limits of 1.0 mgl( - 1) of F( - ) as laid down by BIS and 68% of water exceeded maximum permissible limits of 1.5 mgl( - 1) as prescribed by WHO. The correlation study of fluoride indicated that F( - ) has a significant (p < 0.05) positive relationship with pH (r = +0.59) and RSC (r = 0.54), while a significant negative correlation with Ca+Mg (r = -0.53) and Mg (r = -0.49). The exposure doses of fluoride in infants was found between 0.35 to 3.26 mg kg( - 1)day( - 1) (if dug well water was used) whereas 0.36 to 4.63 mg kg( - 1)day( - 1) (when shallow hand pumps) The exposure doses of water in case of children (20 kg body weight) varied between 0.157 to 1.47 mg kg( - 1)day( - 1) (for dugwell) and 0.162 to 2.08 mg kg( - 1)day( - 1) (for shallow hand pumps) whereas in case of adults (70 kg body weight), it varied between 0.09 to 0.839 mg kg( - 1)day( - 1) (for dugwell) and 0.092 to 1.19 mg kg( - 1)day( - 1) (shallow hand pumps) which is quite high against the standard value of 0.05 mg/kg/day which is the minimum risk level (MRL) calculated by the Agency for Toxic Substances and Disease Registry (ATSDR). The maximum exposure dose to fluoride for adults in the study area found to be 23.8 times higher than the ATSDR's MRL. 相似文献
995.
Sasakawa K 《Die Naturwissenschaften》2007,94(5):384-391
The morphological characteristics of sperm and reproductive organs may offer clues as to how reproductive systems have evolved.
In this paper, the morphologies of the sperm and male reproductive organs of carabid beetles in the tribe Pterostichini (Coleoptera:
Carabidae) are described, and the morphological associations among characters are examined. All species form sperm bundles
in which the head of the sperm was embedded in a rod-shaped structure, i.e., spermatodesm. The spermatodesm shape (left-handed
spiral, right-handed spiral, or without conspicuous spiral structure) and the condition of the sperm on the spermatodesm surface
(with the tail free-moving or forming a thin, sheetlike structure) vary among species. In all species, the spiral directions
of the convoluted seminal vesicles and vasa deferentia are the same on both sides of the body; that is, they show an asymmetric
structure. The species in which the sperm bundle and the seminal vesicles both have a spiral structure could be classified
into two types, with significant differences in sperm-bundle length between the two types. The species with a sperm-bundle
spiral and seminal-vesicle spiral of almost the same diameter have longer sperm bundles than the species with a sperm-bundle
spiral and seminal-vesicle tube of almost the same diameter. In the former type, the spiral directions of the sperm bundles
and seminal vesicles are inevitably the same, whereas they differ in some species with the later type. Therefore, increased
sperm bundle length appears to have been facilitated by the concordance of the sperm bundle’s coiling direction with the coiling
direction of the seminal vesicle. 相似文献
996.
A male gift to its partner? Cyanogenic glycosides in the spermatophore of longwing butterflies (<Emphasis Type="Italic">Heliconius</Emphasis>) 总被引:1,自引:0,他引:1
Males of several insect species transfer nuptial gifts to females during mating, typically in the form of a protein-rich spermatophore.
In chemically defended species, males could potentially enhance such a gift with chemicals that help protect the female, her
eggs, or both. This was shown for lepidopteran species that accumulate pyrrolizidine alkaloids. Most Heliconius butterflies are presumably protected from predators by virtue of de novo synthesized and/or sequestered cyanogenic glycosides.
Males of Heliconius species are known to transfer nutritional gifts to the females but whether defensive chemicals could also be transferred
is not known. To ascertain whether transfer of cyanogens occurs, we dissected freshly mated females from nine different Heliconius species and analyzed spermatophores for cyanogenic glycosides. We found cyanogens in the spermatophores of all nine species.
This is the first time cyanogenic glycosides are reported in the spermatophores of arthropods. We discuss the implications
of these findings for Heliconius biology and for other cyanogenic insects as well. We suggest that chemically defended species commonly lace their nuptial
gifts with defensive chemicals to improve gift quality. 相似文献
997.
Norovirus (NoV) GII.4 is the predominant genotype associated with gastroenteritis pandemics and new strains emerge every 2–3 years. Between 2008 and 2011, environmental studies in South Africa (SA) reported NoVs in 63% of the sewage-polluted river water samples. The aim of this study was to assess whether wastewater samples could be used for routine surveillance of NoVs, including GII.4 variants. From April 2015 to March 2016, raw sewage and effluent water samples were collected monthly from five wastewater treatment plants in SA. A total of 108 samples were screened for NoV GI and GII using real-time RT-qPCR. Overall 72.2% (78/108) of samples tested positive for NoVs with 4.6% (5/108) GI, 31.5% (34/108) GII and 36.1% (39/108) GI + GII strains being detected. Norovirus concentrations ranged from 1.02 × 102 to 3.41 × 106 genome copies/litre for GI and 5.00 × 103 to 1.31 × 106 genome copies/litre for GII. Sixteen NoV genotypes (GI.2, GI.3, GI.4, GI.5, GI.6, GII.2, GII.3, GII.4, GII.7, GII.9, GII.10, GII.14, GII.16, GII.17, GII.20, and GII.21) were identified. Norovirus GII.2 and GII.17 co-dominated and the majority of GII.17 strains clustered with the novel Kawasaki 2014 variant. Sewage surveillance facilitated detection of Kawasaki 2014 in SA, which to date has not been detected with surveillance in children with gastroenteritis <5 years of age. Combined surveillance in the clinical setting and environment appears to be a valuable strategy to monitor emergence of NoV strains in countries that lack NoV outbreak surveillance. 相似文献
998.
Increasingly government agencies are seeking to quantify the outcomes of proposed policy options in terms of ecosystem service
benefits, yet conflicting definitions and ad hoc approaches to measuring ecosystem services have created confusion regarding
how to rigorously link ecological change to changes in human well-being. Here, we describe a step-by-step framework for producing
ecological models and metrics that can effectively serve an economic-benefits assessment of a proposed change in policy or
management. A focus of the framework is developing comparable units of ecosystem goods and services to support decision-making,
even if outcomes cannot be monetized. Because the challenges to translating ecological changes to outcomes appropriate for
economic analyses are many, we discuss examples that demonstrate practical methods and approaches to overcoming data limitations.
The numerous difficult decisions that government agencies must make to fairly use and allocate natural resources provides
ample opportunity for interdisciplinary teams of natural and social scientists to improve methods for quantifying changes
in ecosystem services and their effects on human well-being. This framework is offered with the intent of promoting the success
of such teams as they support managers in evaluating the equivalency of ecosystem service offsets and trades, establishing
restoration and preservation priorities, and more generally, in developing environmental policy that effectively balances
multiple perspectives. 相似文献
999.
For nearly a century researchers have investigated the uptake and utilization of dissolved organic matter (DOM) by marine
invertebrates, but its contribution to their growth, reproduction, and survival remains unclear. Here, the benefit of DOM
uptake was assessed for the marine bryozoan Bugula neritina (Linnaeus 1758) through performance comparisons of individuals in the presence and absence of DOM. The experiments were performed
using B. neritina collected from floating docks in Beaufort, NC, USA from July to September 2004. Seawater was subjected to ultraviolet irradiation
to reduce naturally occurring DOM, and then enriched with either 1 μM of palmitic acid or a mixture containing 1 μM each of
glucose, alanine, aspartic acid and glycine. Larvae in DOM-enriched and DOM-reduced treatments were sampled and induced to
metamorphose following 1, 6, 12, and 24 h of continuous swimming at 25°C. Sampled larvae were assessed for initiation of metamorphosis,
completion of metamorphosis, and ancestrular lophophore size to determine the extent to which energy acquired from DOM uptake
could offset the metabolic costs of prolonged larval swimming. DOM treatment had no significant effect on initiation of metamorphosis,
but did have a significant effect on completion of metamorphosis and lophophore size. Larvae swimming in DOM-enriched treatments
for 24 h experienced a 20% increase in metamorphic completion rate, compared to larvae swimming for 24 h in the DOM-reduced
treatment. In addition, larvae in the amino acid and sugar mixture for 24 h had a significantly larger lophophore surface
area and volume (23 and 31%, respectively), compared to larvae in DOM-depleted seawater. To ensure that the increases in performance
found in larvae with access to DOM were not due to a decrease in metabolic activity, the respiration rates for these larvae
were compared to those of larvae in DOM-depleted seawater. There were no significant differences between these treatments,
indicating that the increases in performance were due to the energy acquired from DOM. These results clearly show that for
B. neritina, DOM uptake results in increased metamorphic success and in the size of the feeding apparatus following an extended larval
swimming duration. 相似文献