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21.
Roe AM  Meyer CB  Nibbelink NP  Ben-David M 《Ecology》2010,91(11):3177-3188
We explored the interacting effects of marine-derived nutrient fertilization and physical disturbance introduced by coastal river otters (Lontra canadensis) on the production and nutrient status of pristine shrub and tree communities in Prince William Sound, Alaska, USA. We compared production of trees and shrubs between latrines and non-latrines, while accounting for otter site selection, by sampling areas on and off sites. Nitrogen stable isotope analysis (delta15N) indicated that dominant tree and shrub species assimilated the marine-derived N excreted by otters. In association with this uptake, tree production increased, but shrub density and nonwoody aboveground shrub production decreased. The reduced shrub production was caused by destruction of ramets, especially blueberry (Vaccinium spp.), through physical disturbance by river otters. False azalea (Menziesia ferruginea) ramets were less sensitive to otter disturbance. Although surviving individual blueberry ramets showed a tendency for increased production per plant, false azalea allocated excess N to storage in leaves rather than growth. We found that plant responses to animal activity vary among species and levels of biological organization (leaf, plant, ecosystem). Such differences should be accounted for when assessing the influence of river otters on the carbon budget of Alaskan coastal forests at the landscape scale.  相似文献   
22.
Three frog species (Limnodynastes tasmaniensis, Limnodynastes fletcheri and Litoria raniformis) were surveyed in rice bays of the Coleambally Irrigation Area (CIA), NSW, Australia, during the rice-growing seasons of 2005/2006 and 2006/2007. A total external morphological abnormality index of 7.0% was observed in frogs of the CIA (n?=?1,209). The types and frequencies of abnormalities were typical of reports from agricultural areas with ectrodactyly being the most common aberration. A relatively low abnormality index of 1.2% was observed in L. raniformis (n?=?87) compared to indices of 7.1% and 8.2% observed in L. fletcheri (n?=?694) and L. tasmaniensis (n?=?428), respectively. No conclusive evidence was found of unnaturally high rates of intersex, gonadal maldevelopment or unbalanced sex ratios in any species. Rice bay surface waters differed significantly in mean pesticide concentrations of atrazine and metolachlor on farms growing rice and corn compared to farms with rice as the sole crop. However, the similar abnormality indices observed in recent metamorphs emerging from these two farm types provided no evidence to suggest a link between larval exposure to the measured pesticides and developmental malformations.  相似文献   
23.
The pelagic yellowtail kingfish Seriola lalandi has become a target species for aquaculture in Asia and Australasia. Australasian production is reliant on larviculture from eggs of captive brood stock; however, knowledge regarding the nutritional requirements of larvae of this species is still scarce, particularly in relation to lipids. As a first step in establishing these requirements, eggs and larvae from captive S. lalandi brood stock were examined for differences in total protein, total lipid and lipid classes between individual spawning events, over the spawning season, and during larval development from fertilisation to 15 days post hatch. Results indicate that total protein egg−1 varied significantly between individual spawning events within a season, but neither total lipid nor total protein egg−1 varied significantly across the spawning season. Brood stock egg lipids were made up of approximately 60% phospholipid, 25% wax and/or sterol esters (WE), 15% triacylglycerol (TAG), and small amounts of sterols and free fatty acids. During the early larval period, both WE and TAG were utilised concurrently for energy. The larvae experienced very high mortality around 5–7 days post hatch, which coincided with very low levels of all neutral lipid classes. Although many other factors may also influence larval mortality, these results indicate that lipid provisioning may be an important factor in larval survival during the critical period around first-feeding in this species. Examination of ratios of TAG:ST, often used as a condition index in fish larvae, suggested that some of the larvae were suffering from starvation. However, as egg-derived WE appears to provide a significant source of energy during the early larval period in S. lalandi, it is suggested that WE should be included in any index of larval nutritional state.  相似文献   
24.
Exploring the response of an ecosystem, and subsequent tradeoffs among its biological community, to human perturbations remains a key challenge for the implementation of an ecosystem approaches to fisheries (EAF). To address this and related issues, we developed two network (or energy budget) models, Ecopath and Econetwrk, for the Gulf of Maine ecosystem. These models included 31 network “nodes” or biomass state variables across a broad range of trophic levels, with the present emphasis to particularly elucidate the role of small pelagics. After initial network balancing, various perturbation scenarios were evaluated to explore how potential changes to different fish, fisheries and lower trophic levels can affect model outputs. Categorically across all scenarios and interpretations thereof, there was minimal change at the second trophic levels and most of the “rebalancing” after a perturbation occurred via alteration of the diet matrix. Yet the model results from perturbations to a balanced energy budget fall into one of three categories. First, some model results were intuitive and in obvious agreement with established ecological and fishing theory. Second, some model results were counter-intuitive upon initial observation, seemingly contradictory to known ecological and fishing theory; but upon further examination the results were explainable given the constraints of an equilibrium energy budget. Finally, some results were counter-intuitive and difficult to reconcile with theory or further examination of equilibrium constraints. A detailed accounting of biomass flows for example scenarios explores some of the non-intuitive results more rigorously. Collectively these results imply a need to carefully track biomass flows and results of any given perturbation and to critically evaluate the conditions under which a new equilibrium is obtained for these types of models, which has implications for dynamic simulations based off of them. Given these caveats, the role of small pelagics as a prominent component of this ecosystem remains a robust conclusion. We discuss how one might use this approach in the context of further developing an EAF, recognizing that a more holistic, integrated perspective will be required as we continue to evaluate tradeoffs among marine biological communities.  相似文献   
25.
Environmental Monitoring and Assessment - Global environmental changes not only contribute to the modification of global pollution transport pathways but can also alter contaminant fate within the...  相似文献   
26.
Behavioral Considerations in Fragmented Landscapes   总被引:1,自引:0,他引:1  
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27.
The purpose of this study was to examine the natural history and differential diagnosis of ultrasound-detected, isolated fetal ascites. Retrospective review of our patient data base, from 1989 to 1993, revealed 18 patients with fetal ascites diagnosed sonographically. Fetuses presenting with generalized hydrops were excluded. One of the 18 fetuses with ascites had a chromosomal abnormality (trisomy 21), four fetuses had intrauterine infections, seven had gastrointestinal processes, two had genitourinary tract abnormalities, and four were labelled as ‘idiopathic’ (all four resulting in normal neonates). Seventeen of 18 fetuses survived; there was one fetal demise secondary to active syphilis. One fetus with parvovirus infection required intrauterine transfusion and did well. Two infants are developmentally retarded, including one with trisomy 21 and one with microcephaly secondary to cytomegalovirus infection. Fourteen of 18 fetuses had documented in-utero resolution of the ascites. Eleven of the 18 were associated with polyhydramnios sometime during fetal life. None of the fetuses developed hydrops. In conclusion, fetal ascites can result from many different aetiologies, including gastrointestinal and genitourinary anomalies. Chromosomal abnormalities and viral aetiologies must also be considered. Fetuses who have isolated ascites can have a good outcome with resolution of the ascites antenatally.  相似文献   
28.
Aim: The aim of this study was to synthesize published qualitative studies to identify older adults' preferences for communication about driving with health care providers.

Background: Health care providers play a key role in addressing driving safety and driving retirement with older adults, but conversations about driving can be difficult. Guides exist for family members and providers, but to date less is known about the types of communication and messages older drivers want from their health care providers.

Design: A qualitative metasynthesis of studies published on or before October 10, 2014, in databases (PubMed, CINAHL, PsycINFO, and Web of Science) and grey literature was performed.

Review Methods: Twenty-two published studies representing 518 older adult drivers met the following inclusion criteria: the study (1) was about driving; (2) involved older drivers; (3) was qualitative (rather than quantitative or mixed methods); and (4) contained information on older drivers' perspectives about communication with health care providers.

Results: We identified 5 major themes regarding older adults' communication preferences: (1) driving discussions are emotionally charged; (2) context matters; (3) providers are trusted and viewed as authority figures; (4) communication should occur over a period of time rather than suddenly; and (5) older adults desire agency in the decision to stop driving.

Conclusion: Various stakeholders involved in older driver safety should consider older drivers' perspectives regarding discussions about driving. Health care providers can respect and empower older drivers—and support their family members—through tactful communication about driving safety and mobility transitions during the life course.  相似文献   

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Congenital anomalies of the kidney and urinary tract (CAKUT) constitute 20% of all congenital malformations occurring in one in 500 live births. Worldwide, CAKUT are responsible for 40% to 50% of pediatric and 7% of adult end-stage renal disease. Pathogenic variants in genes causing CAKUT include monogenic diseases such as polycystic kidney disease and ciliopathies, as well as syndromes that include isolated kidney disease in conjunction with other abnormalities. Prenatal diagnosis most often occurs using ultrasonography; however, further genetic diagnosis may be made using a variety of testing strategies. Family history and pathologic examination can also provide information to improve the ability to make a prenatal diagnosis of CAKUT. Here, we provide a comprehensive overview of genetic considerations in the prenatal diagnosis of CAKUT disorders. Specifically, we discuss monogenic causes of CAKUT, associated ultrasound characteristics, and considerations for genetic diagnosis, antenatal care, and postnatal care.  相似文献   
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