Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 29
Filtrar
1.
Conserv Biol ; : e14301, 2024 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-38801276

RESUMO

People often modify the shoreline to mitigate erosion and protect property from storm impacts. The 2 main approaches to modification are gray infrastructure (e.g., bulkheads and seawalls) and natural or green infrastructure (NI) (e.g., living shorelines). Gray infrastructure is still more often used for coastal protection than NI, despite having more detrimental effects on ecosystem parameters, such as biodiversity. We assessed the impact of gray infrastructure on biodiversity and whether the adoption of NI can mitigate its loss. We examined the literature to quantify the relationship of gray infrastructure and NI to biodiversity and developed a model with temporal geospatial data on ecosystem distribution and shoreline modification to project future shoreline modification for our study location, coastal Georgia (United States). We applied the literature-derived empirical relationships of infrastructure effects on biodiversity to the shoreline modification projections to predict change in biodiversity under different NI versus gray infrastructure scenarios. For our study area, which is dominated by marshes and use of gray infrastructure, when just under half of all new coastal infrastructure was to be NI, previous losses of biodiversity from gray infrastructure could be mitigated by 2100 (net change of biodiversity of +0.14%, 95% confidence interval -0.10% to +0.39%). As biodiversity continues to decline from human impacts, it is increasingly imperative to minimize negative impacts when possible. We therefore suggest policy and the permitting process be changed to promote the adoption of NI.


Cuantificación del impacto de la futura modificación de la costa sobre la biodiversidad en un estudio de caso de la costa de Georgia, Estados Unidos Resumen Las personas modifican con frecuencia la costa para mitigar la erosión o proteger su propiedad del impacto de las tormentas. Los dos enfoques principales para la modificación son la infraestructura gris (p. ej.: mamparos y malecones) y la infraestructura verde o natural (IN) (p.ej.: costas vivientes). La infraestructura gris es más común que la IN, a pesar de que tiene efectos dañinos sobre los parámetros ambientales, como la biodiversidad. Evaluamos el impacto de la infraestructura gris sobre la biodiversidad y si la adopción de la IN puede mitigar su pérdida. Analizamos la literatura para cuantificar la relación de la infraestructura gris y la IN con la biodiversidad. También desarrollamos un modelo con datos geoespaciales temporales sobre la distribución de los ecosistemas y la modificación de la costa para proyectar la modificación costera en el futuro en nuestra localidad de estudio: la costa de Georgia, Estados Unidos. Aplicamos las relaciones empíricas derivadas de la literatura de los efectos de la infraestructura sobre la biodiversidad a las proyecciones de modificación de la costa para predecir el cambio en la biodiversidad bajo diferentes escenarios de infraestructura gris versus IN. En nuestra área de estudio, que está dominada por marismas y usa infraestructura gris, cuando un poco menos de la mitad de toda la infraestructura costera nueva debería ser IN, las pérdidas previas de biodiversidad a partir de la infraestructura gris podrían mitigarse para 2100 (cambio neto de la biodiversidad de +0.14%, 95% intervalo de confianza ­0.10% a +0.39%). Conforme la biodiversidad siga en declive por el impacto humano, cada vez es más imperativo minimizar el impacto negativo cuando sea posible. Por lo tanto, sugerimos que se modifiquen las políticas y el proceso de permisos para promover la adopción de la IN.

2.
Proc Natl Acad Sci U S A ; 120(46): e2214334120, 2023 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-37931104

RESUMO

Civil infrastructure will be essential to face the interlinked existential threats of climate change and rising resource demands while ensuring a livable Anthropocene for all. However, conventional infrastructure planning largely neglects the contributions and maintenance of Earth's ecological life support systems, which provide irreplaceable services supporting human well-being. The stability and performance of these services depend on biodiversity, but conventional infrastructure practices, narrowly focused on controlling natural capital, have inadvertently degraded biodiversity while perpetuating social inequities. Here, we envision a new infrastructure paradigm wherein biodiversity and ecosystem services are a central objective of civil engineering. In particular, we reimagine infrastructure practice such that 1) ecosystem integrity and species conservation are explicit objectives from the outset of project planning; 2) infrastructure practices integrate biodiversity into diverse project portfolios along a spectrum from conventional to nature-based solutions and natural habitats; 3) ecosystem functions reinforce and enhance the performance and lifespan of infrastructure assets; and 4) civil engineering promotes environmental justice by counteracting legacies of social inequity in infrastructure development and nature conservation. This vision calls for a fundamental rethinking of the standards, practices, and mission of infrastructure development agencies and a broadening of scope for conservation science. We critically examine the legal and professional precedents for this paradigm shift, as well as the moral and economic imperatives for manifesting equitable infrastructure planning that mainstreams biodiversity and nature's benefits to people. Finally, we set an applied research agenda for supporting this vision and highlight financial, professional, and policy pathways for achieving it.


Assuntos
Biodiversidade , Ecossistema , Humanos , Mudança Climática , Conservação dos Recursos Naturais
3.
J Environ Manage ; 323: 116138, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36113289

RESUMO

Global environmental factors (e.g., extreme weather, climate action failure, natural disasters, human environmental damage) increasingly threaten coastal communities. Shorelines are often hardened (seawalls, bulkheads) to prevent flooding and erosion and protect coastal communities. However, hardened shorelines lead to environmental degradation and biodiversity loss. Developmental pressures that are growing in scale, scope, and complexity necessitate the development of sustainable solutions to work with, rather than against, nature. Such nature-based solutions (NBS) provide protection and improve environmental quality and enhance biodiversity. To further this pressing need into action, the US Army Corps of Engineers (USACE) began the Engineering With Nature (EWN) initiative to balance economic, environmental, and social benefits through collaboration with partners and stakeholders. This work shows how engineering practice can be advanced through structured decision-making and landscape architecture renderings that include ecological sciences and NBS into an integrated approach for enhancing biodiversity in coastal marine environments. This integrated approach can be applied when designing new infrastructure projects or modifying or repairing existing infrastructure. To help communicate designs incorporating NBS, drawings, and renderings showcasing EWN concepts can aid decision-making. Our experiences with implementing EWN in practice have revealed that involving landscape architects can play a crucial role in successful collaboration and lead to solutions that protect coastal communities while preserving or enhancing biodiversity.


Assuntos
Biodiversidade , Inundações , Conservação dos Recursos Naturais , Ecossistema , Engenharia
4.
Sci Total Environ ; 832: 155078, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35398422

RESUMO

Natural infrastructure (NI) development, including ecosystem restoration, is an increasingly popular approach to leverage ecosystem services for sustainable development, climate resilience, and biodiversity conservation goals. Although implementation and planning for these tools is accelerating, there is a critical need for effective post-implementation monitoring to accumulate performance data and evidence for best practices. The complexity and longer time scales associated with NI, compounded by differing disciplinary definitions and concepts of monitoring necessitate a deliberate and strategic approach to monitoring that encompasses different timeframes and objectives. This paper outlines a typology of monitoring classes differentiated by temporal scale, purpose of data collection, the information benefits of monitoring, and the responsible party. Next, we provide a framework and practical guidelines for designing monitoring plans for NI around learning objectives. In particular, we emphasize conducting research and development monitoring, which provides scientifically rigorous evidence for methodological improvement beyond the project scale. Wherever feasible, and where NI tools are relatively new and untested, such monitoring should avoid wasted effort and ensure progress and refinement of methodology and practice over time. Finally, we propose institutional changes that would promote greater adoption of research and development monitoring to increase the evidence base for NI implementation at larger scales.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Biodiversidade , Conservação dos Recursos Naturais/métodos
5.
Sci Total Environ ; 825: 153952, 2022 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-35189222

RESUMO

Kelp forests affect coastal circulation but their influence on upwelling around headlands is poorly understood. Tidal-cycle surveys off two headlands with contrasting kelp coverage illustrated the influence of kelp forests on headland upwelling. Underway acoustic Doppler current and backscatter profiles were collected simultaneously to surface water temperature. Surveys occurred along three off-headland transects in July 25-29, 2018, off Isla Natividad, located midway on the western coast of the Baja California peninsula. Flows and water temperature distributions off the headland with no kelp coverage were consistent with headland upwelling. In contrast, the kelp around the headland with dense coverage: 1) attenuated the ambient flow; 2) favored an increase in effective radius of flow curvature; 3) promoted flow ducting, which consists of enhancing flow through channels unobstructed by kelp; and 4) suppressed headland upwelling. Kelp suppressed upwelling by channeling the flow away from the headland, keeping nearshore waters warmer than offshore. PLAIN LANGUAGE ABSTRACT: This study documents a way in which biology can affect physics in coastal ocean environments. In particular, the study describes how a kelp forest suppresses the upward pumping of cool subsurface waters that is typically found around headlands. Such suppression of subsurface waters injection occurs via a process that we refer to as 'flow ducting.' In flow ducting, coastal flows are channelized through kelp gaps, concentrated in bands <30 m wide, and kept away from the morphological influences of a headland. This ducting is analogous to the tortuous flow through porous media.


Assuntos
Kelp , Ecossistema , Florestas , México , Água
6.
Sci Rep ; 11(1): 10929, 2021 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-34035327

RESUMO

Declining oxygen is one of the most drastic changes in the ocean, and this trend is expected to worsen under future climate change scenarios. Spatial variability in dissolved oxygen dynamics and hypoxia exposures can drive differences in vulnerabilities of coastal ecosystems and resources, but documentation of variability at regional scales is rare in open-coast systems. Using a regional collaborative network of dissolved oxygen and temperature sensors maintained by scientists and fishing cooperatives from California, USA, and Baja California, Mexico, we characterize spatial and temporal variability in dissolved oxygen and seawater temperature dynamics in kelp forest ecosystems across 13° of latitude in the productive California Current upwelling system. We find distinct latitudinal patterns of hypoxia exposure and evidence for upwelling and respiration as regional drivers of oxygen dynamics, as well as more localized effects. This regional and small-scale spatial variability in dissolved oxygen dynamics supports the use of adaptive management at local scales, and highlights the value of collaborative, large-scale coastal monitoring networks for informing effective adaptation strategies for coastal communities and fisheries in a changing climate.

7.
Proc Biol Sci ; 287(1934): 20201500, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32900320

RESUMO

Marine ecosystems are generally expected to have bottom-heavy trophic structure (more plants than animals) due to size-based constraints arising from increased metabolic requirements and inefficient energy transfer. However, size-based (allometric) approaches are often limited to confined trophic-level windows where energy transfer is predicted by size alone and are constrained to a balance between bottom-up and top-down control at steady state. In real food webs, energy flow is more complex and imbalances in top-down and bottom-up processes can also shape trophic structure. We expand the size-based theory to account for complex food webs and show that moderate levels of food web connectance allow for inverted trophic structure more often than predicted, especially in marine ecosystems. Trophic structure inversion occurs due to the incorporation of complex energy pathways and top-down effects on ecosystems. Our results suggest that marine ecosystems should be top-heavy, and observed bottom-heavy trophic structure may be a result of human defaunation of the ocean that has been more extreme than presently recognized.


Assuntos
Cadeia Alimentar , Animais , Biomassa , Tamanho Corporal , Ecossistema , Modelos Biológicos , Estado Nutricional , Comportamento Predatório
8.
Glob Chang Biol ; 26(11): 6457-6473, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32902090

RESUMO

The changing global climate is having profound effects on coastal marine ecosystems around the world. Structure, functioning, and resilience, however, can vary geographically, depending on species composition, local oceanographic forcing, and other pressures from human activities and use. Understanding ecological responses to environmental change and predicting changes in the structure and functioning of whole ecosystems require large-scale, long-term studies, yet most studies trade spatial extent for temporal duration. We address this shortfall by integrating multiple long-term kelp forest monitoring datasets to evaluate biogeographic patterns and rates of change of key functional groups (FG) along the west coast of North America. Analysis of data from 469 sites spanning Alaska, USA, to Baja California, Mexico, and 373 species (assigned to 18 FG) reveals regional variation in responses to both long-term (2006-2016) change and a recent marine heatwave (2014-2016) associated with two atmospheric and oceanographic anomalies, the "Blob" and extreme El Niño Southern Oscillation (ENSO). Canopy-forming kelps appeared most sensitive to warming throughout their range. Other FGs varied in their responses among trophic levels, ecoregions, and in their sensitivity to heatwaves. Changes in community structure were most evident within the southern and northern California ecoregions, while communities in the center of the range were more resilient. We report a poleward shift in abundance of some key FGs. These results reveal major, ongoing region-wide changes in productive coastal marine ecosystems in response to large-scale climate variability, and the potential loss of foundation species. In particular, our results suggest that coastal communities that are dependent on kelp forests will be more impacted in the southern portion of the California Current region, highlighting the urgency of implementing adaptive strategies to sustain livelihoods and ensure food security. The results also highlight the value of multiregional integration and coordination of monitoring programs for improving our understanding of marine ecosystems, with the goal of informing policy and resource management in the future.


Assuntos
Kelp , Alaska , California , Ecossistema , Florestas , Humanos , México
9.
Sci Rep ; 10(1): 14227, 2020 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-32848179

RESUMO

Climate change is expected to warm, deoxygenate, and acidify ocean waters. Global climate models (GCMs) predict future conditions at large spatial scales, and these predictions are then often used to parameterize laboratory experiments designed to assess biological and ecological responses to future change. However, nearshore ecosystems are affected by a range of physical processes such as tides, local winds, and surface and internal waves, causing local variability in conditions that often exceeds global climate models. Predictions of future climatic conditions at local scales, the most relevant to ecological responses, are largely lacking. To fill this critical gap, we developed a 2D implementation of the Regional Ocean Modeling System (ROMS) to downscale global climate predictions across all Representative Concentration Pathway (RCP) scenarios to smaller spatial scales, in this case the scale of a temperate reef in the northeastern Pacific. To assess the potential biological impacts of local climate variability, we then used the results from different climate scenarios to estimate how climate change may affect the survival, growth, and fertilization of a representative marine benthic invertebrate, the red abalone Haliotis rufescens, to a highly varying multi-stressor environment. We found that high frequency variability in temperature, dissolved oxygen (DO), and pH increases as pCO2 increases in the atmosphere. Extreme temperature and pH conditions are generally not expected until RCP 4.5 or greater, while frequent exposure to low DO is already occurring. In the nearshore environment simulation, strong RCP scenarios can affect red abalone growth as well as reduce fertilization during extreme conditions when compared to global scale simulations.

10.
Am Nat ; 193(3): 391-408, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30794455

RESUMO

For many species, reproductive failure may occur if abundance drops below critical Allee thresholds for successful breeding, in some cases impeding recovery. At the same time, extreme environmental events can cause catastrophic collapse in otherwise healthy populations. Understanding what natural processes and management strategies may allow for persistence and recovery of natural populations is critical in the face of expected climate change scenarios of increased environmental variability. Using a spatially explicit continuous-size fishery model with stochastic dispersal parameterized for abalone-a harvested species with sedentary adults and a dispersing larval phase-we investigated whether the establishment of a system of marine protected areas (MPAs) can prevent population collapse, compared with nonspatial management when populations are affected by mass mortality from environmental shocks and subject to Allee effects. We found that MPA networks dramatically reduced the risk of collapse following catastrophic events (75%-90% mortality), while populations often continued to decline in the absence of spatial protection. Similar resilience could be achieved by closing the fishery immediately following mass mortalities but would necessitate long periods without catch and therefore economic income. For species with Allee effects, the use of protected areas can ensure persistence following mass mortality events while maintaining ecosystem services during the recovery period.


Assuntos
Conservação dos Recursos Naturais/métodos , Pesqueiros , Gastrópodes , Modelos Teóricos , Animais , Dinâmica Populacional
11.
PLoS One ; 13(8): e0203231, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30169532

RESUMO

A coupled numerical model is developed to examine aggregative behavior in instances where the behavior not only responds to the environment, but the environment responds to the behavior such as fish schooling and penguin huddling. In the coupled model, the full Navier-Stokes equations are solved for the wind field using a finite difference method (FDM), and coupled to a smoothed particle hydrodynamics (SPH) model adapted to simulate animal behavior (penguins are individual particles in the SPH). We use the model to examine the dynamics of penguin huddling as a purely individual fitness maximizing behavior. SPH is a mesh-free Lagrangian method driven by local interactions between neighboring fluid particles and their environment allowing particles to act as free ranging 'animals' unconstrained by a computational grid that implicitly interact with one another (a critical element of aggregative behavior). The coupled model is recomputed simultaneously as the huddle evolves over time to update individual particle positions, redefine the properties of the developing huddle (i.e., shape and density), and adjust the wind field flowing through and around the dynamic huddle. This study shows the ability of a coupled model to predict the dynamic properties of penguin huddling, to quantify biometrics of individual particle "penguins", and to confirm communal penguin huddling behavior as an individualistic behavior.


Assuntos
Comportamento Animal , Meio Ambiente , Modelos Biológicos , Spheniscidae , Animais , Regulação da Temperatura Corporal , Simulação por Computador , Hidrodinâmica , Atividade Motora , Temperatura , Fatores de Tempo
12.
Sci Rep ; 8(1): 5501, 2018 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-29615671

RESUMO

Climate change is causing warming, deoxygenation, and acidification of the global ocean. However, manifestation of climate change may vary at local scales due to oceanographic conditions. Variation in stressors, such as high temperature and low oxygen, at local scales may lead to variable biological responses and spatial refuges from climate impacts. We conducted outplant experiments at two locations separated by ~2.5 km and two sites at each location separated by ~200 m in the nearshore of Isla Natividad, Mexico to assess how local ocean conditions (warming and hypoxia) may affect juvenile abalone performance. Here, we show that abalone growth and mortality mapped to variability in stress exposure across sites and locations. These insights indicate that management decisions aimed at maintaining and recovering valuable marine species in the face of climate change need to be informed by local variability in environmental conditions.


Assuntos
Mudança Climática , Gastrópodes , Oceanografia , Animais , Gastrópodes/metabolismo , Gastrópodes/fisiologia , Oxigênio/metabolismo , Estações do Ano , Temperatura
13.
Nat Commun ; 9(1): 23, 2018 01 02.
Artigo em Inglês | MEDLINE | ID: mdl-29295998

RESUMO

Size generally dictates metabolic requirements, trophic level, and consequently, ecosystem structure, where inefficient energy transfer leads to bottom-heavy ecosystem structure and biomass decreases as individual size (or trophic level) increases. However, many animals deviate from simple size-based predictions by either adopting generalist predatory behavior, or feeding lower in the trophic web than predicted from their size. Here we show that generalist predatory behavior and lower trophic feeding at large body size increase overall biomass and shift ecosystems from a bottom-heavy pyramid to a top-heavy hourglass shape, with the most biomass accounted for by the largest animals. These effects could be especially dramatic in the ocean, where primary producers are the smallest components of the ecosystem. This approach makes it possible to explore and predict, in the past and in the future, the structure of ocean ecosystems without biomass extraction and other impacts.


Assuntos
Ecossistema , Peixes/fisiologia , Cadeia Alimentar , Modelos Biológicos , Animais , Antozoários/classificação , Antozoários/fisiologia , Biomassa , Tamanho Corporal , Comportamento Alimentar/fisiologia , Pesqueiros/estatística & dados numéricos , Pesqueiros/tendências , Peixes/classificação , Oceanos e Mares , Plâncton/classificação , Plâncton/fisiologia , Dinâmica Populacional , Comportamento Predatório/fisiologia
14.
Ann Rev Mar Sci ; 10: 421-441, 2018 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-28796571

RESUMO

Internal waves are widespread features of global oceans that play critical roles in mixing and thermohaline circulation. Similarly to surface waves, internal waves can travel long distances, ultimately breaking along continental margins. These breaking waves can transport deep ocean water and associated constituents (nutrients, larvae, and acidic low-oxygen waters) onto the shelf and locally enhance turbulence and mixing, with important effects on nearshore ecosystems. We are only beginning to understand the role internal waves play in shaping nearshore ecosystems. Here, I review the physics of internal waves in shallow waters and identify two commonalities among internal waves in the nearshore: exposure to deep offshore waters and enhanced turbulence and mixing. I relate these phenomena to important ecosystem processes ranging from extreme events to fertilization success to draw general conclusions about the influence of internal waves on ecosystems and the effects of internal waves in a changing climate.


Assuntos
Ecossistema , Hidrodinâmica , Oceanos e Mares , Água do Mar/química , Movimentos da Água , Mudança Climática
15.
Proc Natl Acad Sci U S A ; 112(6): 1710-5, 2015 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-25624488

RESUMO

Long-term changes in nutrient supply and primary production reportedly foreshadow substantial declines in global marine fishery production. These declines combined with current overfishing, habitat degradation, and pollution paint a grim picture for the future of marine fisheries and ecosystems. However, current models forecasting such declines do not account for the effects of ocean fronts as biogeochemical hotspots. Here we apply a fundamental technique from fluid dynamics to an ecosystem model to show how fronts increase total ecosystem biomass, explain fishery production, cause regime shifts, and contribute significantly to global biogeochemical budgets by channeling nutrients through alternate trophic pathways. We then illustrate how ocean fronts affect fishery abundance and yield, using long-term records of anchovy-sardine regimes and salmon abundances in the California Current. These results elucidate the fundamental importance of biophysical coupling as a driver of bottom-up vs. top-down regulation and high productivity in marine ecosystems.


Assuntos
Ecossistema , Pesqueiros/estatística & dados numéricos , Modelos Teóricos , Movimentos da Água , Biomassa , Simulação por Computador , Hidrodinâmica , Oceanos e Mares , Dinâmica Populacional
16.
J Exp Biol ; 215(Pt 6): 1008-16, 2012 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-22357594

RESUMO

Plankton are small organisms that dwell in oceans, seas and bodies of fresh water. In this review, we discuss life in the plankton, which involves a balance between the behavioral capabilities of the organism and the characteristics and movement of the water that surrounds it. In order to consider this balance, we discuss how plankton interact with their environment across a range of scales - from the smallest viruses and bacteria to larger phytoplankton and zooplankton. We find that the larger scale distributions of plankton, observed in coastal waters, along continental shelves and in ocean basins, are highly dependent upon the smaller scale interactions between the individual organism and its environment. Further, we discuss how larger scale organism distributions may affect the transport and/or retention of plankton in the ocean environment. The research reviewed here provides a mechanistic understanding of how organism behavior in response to the physical environment produces planktonic aggregations, which has a direct impact on the way marine ecosystems function.


Assuntos
Plâncton/fisiologia , Movimentos da Água , Organismos Aquáticos/fisiologia , Modelos Biológicos , Movimento/fisiologia , Oceanos e Mares
17.
Integr Comp Biol ; 47(6): 831-46, 2007 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21669762

RESUMO

Several species and developmental stages of calanoid copepods were tested for responses to environmental cues in a laboratory apparatus that mimicked conditions commonly associated with patches of food in the ocean. All species responded to the presence of phytoplankton by feeding. All species responded by increasing proportional residence time in one, but not both, of the treatments defined by gradients of velocity or density. Most species increased swimming speed and frequency of turning in response to the presence of chemical exudates or gradients of velocity. Only one species, Eurytemora affinis, increased proportional time of residence in response to gradients in density of the water. Responses of E. affinis to combined cues did not definitively demonstrate a hierarchical use of different cues as previously observed for Temora longicornis and Acartia tonsa. A simple foraging simulation was developed to assess the applicability in the field of the behavioral results observed in the laboratory. These simulations suggest that observed fine-scale behaviors could lead to copepod aggregations observed in situ. The present study demonstrates that behavioral response to cues associated with fine-scale oceanographic gradients and biological patchiness is functionally important and prevalent among copepods and likely has significant impacts on larger-scale distributional patterns.

18.
Ecology ; 87(11): 2821-31, 2006 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17168026

RESUMO

Microbes are known to affect ecosystems and communities as decomposers, pathogens, and mutualists. However, they also may function as classic consumers and competitors with animals if they chemically deter larger consumers from using rich food-falls such as carrion, fruits, and seeds that can represent critical windfalls to both microbes and animals. Microbes often use chemicals (i.e., antibiotics) to compete against other microbes. Thus using chemicals against larger competitors might be expected and could redirect significant energy subsidies from upper trophic levels to the detrital pathway. When we baited traps in a coastal marine ecosystem with fresh vs. microbe-laden fish carrion, fresh carrion attracted 2.6 times as many animals per trap as microbe-laden carrion. This resulted from fresh carrion being found more frequently and from attracting more animals when found. Microbe-laden carrion was four times more likely to be uncolonized by large consumers than was fresh carrion. In the lab, the most common animal found in our traps (the stone crab Menippe mercenaria) ate fresh carrion 2.4 times more frequently than microbe-laden carrion. Bacteria-removal experiments and feeding bioassays using organic extracts of microbe-laden carrion showed that bacteria produced noxious chemicals that deterred animal consumers. Thus bacteria compete with large animal scavengers by rendering carcasses chemically repugnant. Because food-fall resources such as carrion are major food subsidies in many ecosystems, chemically mediated competition between microbes and animals could be an important, common, but underappreciated interaction within many communities.


Assuntos
Bactérias/metabolismo , Braquiúros/fisiologia , Ecossistema , Comportamento Alimentar/fisiologia , Cadeia Alimentar , Animais , Antibacterianos/farmacologia , Bactérias/química , Bactérias/classificação , Bactérias/genética , Comportamento Animal/fisiologia , Cloranfenicol/farmacologia , Comportamento de Escolha/fisiologia , Éter/química , Peixes/microbiologia , Peixes/fisiologia , Gastrópodes/fisiologia , RNA Ribossômico 16S/genética
20.
Med Clin North Am ; 86(1): 47-62, 2002 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-11795090

RESUMO

Especially in the United States, homeopathy has not become integrated into mainstream medical practice; this is partly because of the historical paucity of quality published research studies or quality educational programs. More recently, there have been better-designed studies in reputable journals, although historically most studies have been inconclusive or of poor methodology. The confusion around homeopathy in the United States exists for several reasons: 1. One of the main reasons for the relative disinterest or opposition to homeopathy is that even well-designed clinical studies on homeopathy leave the reader without any protocol-driven tools to take into daily practice. Individualization of treatment, or, as it is called today, differential therapeutics, is the main requirement of successful homeopathic prescribing. Only well-trained homeopathic practitioners are able to carry out such a task. In many articles that reported positive outcomes for homeopathy, numerous homeopathic remedies had been prescribed for the same diagnostic category. Critics suggest that the pooling of data from trials using different therapeutic agents to assess the overall success of homeopathic prescribing is incorrect. Research protocols that employ combination remedies, in which a medication contains several homeopathic remedies, fall into the same category. 2. Many of the positive and negative studies published are flawed with numerous methodologic problems. One of the most common problems is a lack of objective validated outcome measures. Another common problem is a small sample size. In most positive and negative meta-analyses published to date, research data are pulled together artificially based on either a diagnostic category or a particular remedy. Frequently the concentration of the remedy used and the conditions to which it has been applied are different. Ernst and Pittler published a letter with a critique of the methodology used in one of the meta-analyses of clinical trials of homeopathy. Most importantly, professional homeopaths and conventional scientists criticize the choice of remedy or the condition to which it was applied or both. The design and follow-up in migraine studies has been criticized extensively by one of the world's leading homeopaths, Vithoulkas (personal communication, 1997). Most of the Arnica studies have been designed with either an inappropriate dosing regimen or an inappropriately chosen procedure. In most positive studies on homeopathy, the outcome measures were subjective and poorly quantifiable. 3. Few well-designed studies have been reproduced by independent research teams. This situation exists for two major reasons: lack of sufficient funding and lack of a sufficient number of well-trained homeopaths qualified and interested to participate in research. 4. More rigorous educational programs on homeopathy for professionals need to be encouraged. Most of the existing programs are designed for consumers; academic continuing medical education-quality courses are needed. Meanwhile, while the debate around homeopathy still continues in conventional medical circles, the general public has been using the services of homeopathic practitioners and homeopathic remedies increasingly. In many countries, homeopathy and other complementary modalities have been integrated successfully into a larger armamentarium for the modern physician. According to a study published in 1995 in the Journal of the American Board of Family Practice, 69% of family practice physicians expressed interest in learning more about homeopathy. Increasing public and professional interest calls for attempts to study homeopathy in a more systematic way and to provide quality academic overview for medical practitioners. The growing number of complementary and alternative medicine centers affiliated with major teaching hospitals should provide a solid interface between evidence-based biologic medicine and many emerging complementary and alternative medicine modalities, including homeopathy.


Assuntos
Homeopatia/métodos , Homeopatia/educação , Humanos , Metanálise como Assunto , Ensaios Clínicos Controlados Aleatórios como Assunto , Pesquisa , Resultado do Tratamento , Estados Unidos
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...