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881.
Aquaculture studies have revealed that polyunsaturated fatty acids are critical for maintaining substantial growth, survival
and reproductive rates, and high food conversion efficiencies for a wide variety of marine and freshwater organisms. The aim
of this study was to investigate the gross biochemical and fatty acid composition of both neutral and polar lipid compartments
of the razor clam Solen marginatus throughout embryonic and larval development. High levels of stored reserves in S. marginatus eggs allow a short larval development, lasting only 8 days. The energy required for embryogenesis was obtained from stored
proteins. During larval development from D-shaped veliger until settlement, protein, lipid, and carbohydrate reserves were
indistinctly stored for metamorphosis. Although total lipids increased, fatty acids in both neutral and polar lipids decreased
during embryonic development. The depots allow a short larval development in which settlement is reached with lower amounts
of stored neutral and polar lipids than the contents found in the oocytes. Non-methylene-interrupted dienoic fatty acid levels
were similar to those of some polyunsaturated fatty acids, with increasing percentages at the onset of metamorphosis. This
study indicates that S. marginatus exhibits a different pattern in the use of gross biochemical and fatty acid reserves during larval development compared to
other razor clam and bivalve species, mainly due to the large size of its eggs and the short larval development stage reported
in this species. 相似文献
882.
Patricia N. Pochelon Teresa Lopes da Silva Alberto Reis Antonina dos Santos Henrique Queiroga Ricardo Calado 《Marine Biology》2011,158(12):2825-2833
The present study investigated the existence of inter-individual and within-brood variability in the fatty acid (FA) profile
of developing embryos of Nephrops norvegicus. In all surveyed females (n = 5), the quantitatively most important FAs were as follows: 22:6n-3 (20.8 ± 3.9% average of total FA ± standard error),
18:1n-9 (19.5 ± 2.0%), 16:0 (15.2 ± 3.4%), 20:5n-3 (10.2 ± 1.4%), 16:1n-7 (8.9 ± 1.6%), and 18:1n-7 (5.7 ± 1.3%). Differences
in FA profiles of embryos in the same clutch were assessed using brooding chamber side (left and right) and pleopod (1st and
2nd, 3rd and 4th, and 5th) as predictive factors. There were no significant differences in the FA composition of embryos sampled
from both sides of the brooding chamber in 4 of the 5 surveyed females. However, all females exhibited significant differences
in the FA profiles of embryos sampled from different pleopods. Both saturated FA (SFA) and highly unsaturated FA (HUFA) present
in developing embryos exhibited marked differences along the breeding chamber. Overall, FA reserves appeared to vary significantly
within broods, which can ultimately be reflected on early larval survival. A potential cause for the within-brood variation
recorded in the FA profile of developing embryos include (1) differential female investment during ovarian maturation, mainly
due to variation in food quality/availability; (2) differential lipid catabolism during the incubation period of developing
embryos, as a consequence of embryos position within the female’s brooding chamber; or (3) differential female investment
during ovarian maturation amplified by differential lipid catabolism during the incubation period. 相似文献
883.
Ana Paula Madeira Di Beneditto Cristina Maria Magalhães de Souza Helena Amaral Kehrig Carlos Eduardo Rezende 《Marine Biology》2011,158(10):2209-2217
The feeding preferences of the coastal dolphins Pontoporia blainvillei and Sotalia guianensis in south-eastern Brazil (21o18′S–22o25′S) were assessed through the prey’s index of relative importance (IRI), total mercury
concentration (Hgtot), and stable isotopic (δ15N and δ13C) to compare their efficiency in the discrimination of prey contribution to the predators’ diet. The IRI was the best tool
to describe the dolphins’ preference, while Hgtot and δ15N seemed to be efficient as a trophic marker when the diet is made up of prey of varying sizes, as observed in S. guianensis. Both dolphins presented lighter δ15N than their prey species, which is an unusual pattern. However, as the sample size to isotope ratios analysis was small,
especially to the dolphins, the results should be considered with caution, and further studies are necessary to corroborate
these findings. The δ13C values characterized a typical coastal food chain, confirming the preferential area of these species. 相似文献
884.
M.V. Morales-ZárateS.E. Lluch-Cota E. Serviere-ZaragozaS. Guzmán del Próo 《Ecological modelling》2011,222(5):1185-1191
A trophic structure model of the rocky coastal ecosystem in Bahia Tortugas, Mexico was constructed using Ecopath software to represent the main biomass flows in the system. Data for the model came from field observations (biomass estimates, stomach contents, and ecological observations for sea snails, abalones, lobster, some demersal finfishes, and macroalgae) carried out through ten field trips from 2006 to 2008. The results provide a snapshot of how the ecosystem operates. The model considers 23 functional groups. The total system throughput was 553 t/km2/year, 57% corresponds to internal consumption, 28% to respiration, 14% becomes detritus, and only 1% is removed through commercial fishing. The model suggests that even for exploited populations, predation and competition are heavier stresses than current fishing effort; however, because spiny lobster showed the second highest keystoneness’ index value, increasing fishing pressure on this group could strongly impact the entire ecosystem. We believe that this model has the potential to support management by allowing the exploration of the potential impacts of different fishing decisions at ecosystem level. 相似文献
885.
Elbroch M Mwampamba TH Santos MJ Zylberberg M Liebenberg L Minye J Mosser C Reddy E 《Conservation biology》2011,25(6):1195-1202
Abstract: Evidence suggests that the involvement of local people in conservation work increases a project's chances of success. Involving citizen scientists in research, however, raises questions about data quality. As a tool to better assess potential participants for conservation projects, we developed a knowledge gradient, K, along which community members occupy different positions on the basis of their experience with and knowledge of a research subject. This gradient can be used to refine the citizen–science concept and allow researchers to differentiate between community members with expert knowledge and those with little knowledge. We propose that work would benefit from the inclusion of select local experts because it would allow researchers to harness the benefits of local involvement while maintaining or improving data quality. We used a case study from the DeHoop Nature Preserve, South Africa, in which we conducted multiple interviews, identified and employed a local expert animal tracker, evaluated the expert's knowledge, and analyzed the data collected by the expert. The expert animal tracker J.J. created his own sampling design and gathered data on mammals. He patrolled 4653 km in 214 days and recorded 4684 mammals. He worked from a central location, and his patrols formed overlapping loops; however, his data proved neither spatially nor temporally autocorrelated. The distinctive data collected by J.J. are consistent with the notion that involving local experts can produce reliable data. We developed a conceptual model to help identify the appropriate participants for a given project on the basis of research budget, knowledge or skills needed, technical literacy requirements, and scope of the project. 相似文献
886.
Eduardo V. V. Varej?o Carlos R. Bellato Maur��cio P. F. Fontes Jaime W. V. Mello 《Environmental monitoring and assessment》2011,172(1-4):631-642
The Iron Quadrangle has been one of the most important gold production regions in Brazil since the end of the seventeenth century. There, arsenic occurs in close association with sulfide-rich auriferous rocks. The most abundant sulfide minerals are pyrite and arsenopyrite, yet trace metal sulfides occur in subordinate phases as well. Historical mining activities have been responsible for the release of As and trace metals to both aquatic and terrestrial environments close to mining sites in the region. Therefore, this study was aimed to evaluate the distribution and mobility of As, Cd, Co, Cr, Cu, Ni, Pb, and Zn in streams in the southeast portion of the Iron Quadrangle between the municipalities of Ouro Preto and Mariana, the oldest Brazilian Au mining province. Total concentrations of some trace metals and arsenic in water were determined. The four-stage sequential extraction procedure proposed by the commission of the European Communities Bureau of Reference (BCR) was used to investigate the distribution of these elements in stream sediments. Arsenic concentration in water was >10 ??g L???1 (maximum limit permitted by Brazilian environmental regulations for water destined for human consumption) at all sampling sites, varying between 36.7 and 68.3 ??g L???1. Sequential extraction in sediments showed high concentrations of As and trace metals associated with easily mobilized fractions. 相似文献
887.
Fagundes Soares Garcia AC Marcon AE Ferreira Dde M Barbosa dos Santos EA do Amaral VS de Medeiros SR 《Journal of environmental monitoring : JEM》2011,13(12):3329-3335
The present study evaluated the mutagenic potential of surface water from the Lucrecia dam. The Tradescantia-micronucleus (Trad-MCN) test and CBMN assay in human peripheral blood lymphocytes were applied, corresponding to an in vivo and in vitro system, respectively. Heavy metals and some physicochemical properties were also measured. Water samples were collected in November 2009 (dry season) and May 2010 (rainy season) at three different points. Results of both assays for raw water showed positive responses for the points analyzed when compared to the negative control. The CBMN assay showed that diluted water was still able to induce a significant increase in micronucleus frequency. For both assays, the highest mean MN was observed in the dry season. Chemical analyses detected an increase in heavy metal levels at the sampling points and in the different seasons. These findings indicate the presence of genotoxins, such as heavy metals, in the water, which may be affecting the entire ecosystem, as well as human health. More prolonged monitoring is recommended in order to better characterize this public water supply. 相似文献
888.
Santos JA Galante-Oliveira S Barroso C 《Journal of environmental monitoring : JEM》2011,13(3):673-680
The current work presents an innovative statistical approach to model ordinal variables in environmental monitoring studies. An ordinal variable has values that can only be compared as "less", "equal" or "greater" and it is not possible to have information about the size of the difference between two particular values. The example of ordinal variable under this study is the vas deferens sequence (VDS) used in imposex (superimposition of male sexual characters onto prosobranch females) field assessment programmes for monitoring tributyltin (TBT) pollution. The statistical methodology presented here is the ordered logit regression model. It assumes that the VDS is an ordinal variable whose values match up a process of imposex development that can be considered continuous in both biological and statistical senses and can be described by a latent non-observable continuous variable. This model was applied to the case study of Nucella lapillus imposex monitoring surveys conducted in the Portuguese coast between 2003 and 2008 to evaluate the temporal evolution of TBT pollution in this country. In order to produce more reliable conclusions, the proposed model includes covariates that may influence the imposex response besides TBT (e.g. the shell size). The model also provides an analysis of the environmental risk associated to TBT pollution by estimating the probability of the occurrence of females with VDS ≥ 2 in each year, according to OSPAR criteria. We consider that the proposed application of this statistical methodology has a great potential in environmental monitoring whenever there is the need to model variables that can only be assessed through an ordinal scale of values. 相似文献
889.
Bergamasco AM Eldridge M Sanseverino J Sodré FF Montagner CC Pescara IC Jardim WF Umbuzeiro Gde A 《Journal of environmental monitoring : JEM》2011,13(11):3288-3293
Estrogenic Endocrine Disrupting Chemicals (EDCs) are a concern due to their ubiquity and recognized adverse effects to humans and wildlife. Methods to assess exposure to and associated risks of their presence in aquatic environment are still under development. The aim of this work is to assess estrogenicity of raw and treated waters with different degrees of pollution. Chemical analyses of selected EDCs were performed by liquid chromatography-tandem mass spectrometry, and estrogenic activity was evaluated using in vitro bioluminescent yeast estrogen assay (BLYES). Most raw water samples (18/20) presented at least one EDC and 16 rendered positive in BLYES. When EDCs were detected, the bioassay usually provided a positive response, except when only bisphenol A was detected at low concentrations. The highest values of estrogenic activity were detected in the most polluted sites. The maximum estrogenic activity observed was 8.7 ng equiv. of E2 L(-1). We compared potencies observed in the bioassay to the relative potency of target compounds and their concentrations failed to fully explain the biological response. This indicates that bioassay is more sensitive than the chemical approach either detecting estrogenic target compounds at lower concentrations, other non-target compounds or even synergistic effects, which should be considered on further investigations. We have not detected either estrogenic activity or estrogenic compounds in drinking water. BLYES showed good sensitivity with a detection limit of 0.1 ng equiv. E2 L(-1) and it seems to be a suitable tool for water monitoring. 相似文献
890.
Quantifying the Effects of Forest Management Strategies on the Production of Forest Values: Timber,Carbon, Oxygen,Water, and Soil 总被引:1,自引:0,他引:1
Emin Zeki Başkent Sedat Keleş Ali İhsan Kadıoğulları Özkan Bingöl 《Environmental Modeling and Assessment》2011,16(2):145-152
Forest management practices alter forest structure quantified with ecosystem characteristics and values. In this paper, we utilized a forest management simulation model to assess the effects of three forest management strategies focusing on timber production, carbon sequestration, oxygen production, soil erosion, and water production of a forest management unit in Turkey. A forest simulation model “ETÇAPSimülasyon” was developed and used to project forest ecosystem development over 100 years under three forest management policies of timber-oriented forest management (TFM), multipurpose forest management (MFM), and no intervention (NI). The results showed that TFM strategy produced more timber and its net present value than MFM and NI strategies did. The amount of carbon sequestration and oxygen production potential was also found to be the highest with TFM strategy than with the MFM and NI strategies. Compared with the other strategies, however, NI strategy produced the highest amount of water production and soil losses over the planning horizon. The effects of a forest management strategy depend mainly on the initial forest structure, the rate of development and the level of forest management interventions. Therefore, forest dynamics under various management strategies should be explained before the final management decision. Understanding long-term effects of any management strategies on forest structure will provide the basis for better reaching the management objectives. 相似文献