RESUMEN
Trait-based approaches are increasingly recognized as a tool for understanding ecosystem re-assembly and function under intensifying global change. Here we synthesize trait-based research globally (n = 865 studies) to examine the contexts in which traits may be used for global change prediction. We find that exponential growth in the field over the last decade remains dominated by descriptive studies of terrestrial plant morphology, highlighting significant opportunities to expand trait-based thinking across systems and taxa. Very few studies (less than 3%) focus on predicting ecological effects of global change, mostly in the past 5 years and via singular traits that mediate abiotic limits on species distribution. Beyond organism size (the most examined trait), we identify over 2500 other morphological, physiological, behavioural and life-history traits known to mediate environmental filters of species' range and abundance as candidates for future predictive global change work. Though uncommon, spatially explicit process models-which mechanistically link traits to changes in organism distributions and abundance-are among the most promising frameworks for holistic global change prediction at scales relevant for conservation decision-making. Further progress towards trait-based forecasting requires addressing persistent barriers including (1) matching scales of multivariate trait and environment data to focal processes disrupted by global change, and (2) propagating variation in trait and environmental parameters throughout process model functions using simulation.
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Ecología , Ecosistema , Simulación por Computador , FenotipoRESUMEN
Predation from the invasive Indo-Pacific lionfish is likely to amplify declines in marine fishes observed in multiple ocean basins. As the invasion intensifies and expands, there is an urgent need to identify species that are most at risk for extirpation-and possible extinction-from this added threat. To address this gap and inform conservation plans, we develop and apply a quantitative framework for classifying the relative vulnerability of fishes based on morphological and behavioural traits known to influence susceptibility to lionfish predation (e.g. body shape, water column position and aggregation behaviour), habitat overlap with lionfish, and degree of geographic range restriction. Applying the framework to fishes across the invaded Caribbean Sea and ahead of the invasion front in the southwestern Atlantic revealed the identity of at least 77 fishes with relatively small ranges that are likely to be most affected by lionfish predation. Trait-based vulnerability scores significantly predict the probability of fishes appearing within the diets of lionfish across the invaded region. Spatial richness analyses reveal hotspots of vulnerable species in the Bahamas, Belize and Curaçao. Crucially, our framework identifies 29 vulnerable fishes endemic to Brazil, which has not yet been colonized by lionfish. Of these, we suggest reefs around offshore island groups occupied by a dozen highly vulnerable and range-restricted species as priorities for intervention should lionfish spread to the region. Observations of the rate of lionfish spread across the invaded range suggest that an average of 5 years (with a median of nearly 2 years) elapses from first sighting to maximum observed densities. This lag may allow managers to mobilize plans to suppress lionfish ahead of an invasion front in priority locations. Our framework also provides a method for assessing the relative vulnerability of cryptobenthic and/or deep-reef fishes, for which population-monitoring data are limited.
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Arrecifes de Coral , Especies Introducidas , Animales , Ecosistema , Peces , Conducta PredatoriaRESUMEN
We explored patterns, rates and unexpected socio-ecological consequences of tooth replacement in serrasalmids and characids of the Peruvian Amazon using microcomputed tomography. Of 24 specimens collected in February 2019, representing a mix of red-bellied piranha Pygocentrus nattereri, redeye piranha Serrasalmus rhombeus, silver dollar fish Ctenobrycon hauxwellianus and mojara Astyanax abramis, six individuals possessed edentulous jaw quadrants. On average, 22.9% of fish collected per day from these species featured incomplete dentition, a value three to five times higher than anticipated based on replacement rates estimated from captive fish, differences that may be driven by ontogeny, seasonality or environmental quality.
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Characidae/fisiología , Explotaciones Pesqueras , Diente/fisiología , Animales , Perú , Especificidad de la Especie , Microtomografía por Rayos XRESUMEN
Species invasions have a range of negative effects on recipient ecosystems, and many occur at a scale and magnitude that preclude complete eradication. When complete extirpation is unlikely with available management resources, an effective strategy may be to suppress invasive populations below levels predicted to cause undesirable ecological change. We illustrated this approach by developing and testing targets for the control of invasive Indo-Pacific lionfish (Pterois volitans and P. miles) on Western Atlantic coral reefs. We first developed a size-structured simulation model of predation by lionfish on native fish communities, which we used to predict threshold densities of lionfish beyond which native fish biomass should decline. We then tested our predictions by experimentally manipulating lionfish densities above or below reef-specific thresholds, and monitoring the consequences for native fish populations on 24 Bahamian patch reefs over 18 months. We found that reducing lionfish below predicted threshold densities effectively protected native fish community biomass from predation-induced declines. Reductions in density of 2592%, depending on the reef, were required to suppress lionfish below levels predicted to overconsume prey. On reefs where lionfish were kept below threshold densities, native prey fish biomass increased by 5070%. Gains in small (<6 cm) size classes of native fishes translated into lagged increases in larger size classes over time. The biomass of larger individuals (>15 cm total length), including ecologically important grazers and economically important fisheries species, had increased by 1065% by the end of the experiment. Crucially, similar gains in prey fish biomass were realized on reefs subjected to partial and full removal of lionfish, but partial removals took 30% less time to implement. By contrast, the biomass of small native fishes declined by >50% on all reefs with lionfish densities exceeding reef-specific thresholds. Large inter-reef variation in the biomass of prey fishes at the outset of the study, which influences the threshold density of lionfish, means that we could not identify a single rule of thumb for guiding control efforts. However, our model provides a method for setting reef-specific targets for population control using local monitoring data. Our work is the first to demonstrate that for ongoing invasions, suppressing invaders below densities that cause environmental harm can have a similar effect, in terms of protecting the native ecosystem on a local scale, to achieving complete eradication.
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Conservación de los Recursos Naturales/métodos , Monitoreo del Ambiente/métodos , Peces/fisiología , Especies Introducidas , Modelos Biológicos , Control de Plagas , Distribución Animal , Animales , Simulación por Computador , Arrecifes de Coral , Peces/clasificaciónRESUMEN
Understanding how predators select their prey can provide important insights into community structure and dynamics. However, the suite of prey species available to a predator is often spatially and temporally variable. As a result, species-specific selectivity data are of limited use for predicting novel predator-prey interactions because they are assemblage specific. We present a method for predicting diet selection that is applicable across prey assemblages, based on identifying general morphological and behavioural traits of prey that confer vulnerability to predation independent of species identity. We apply this trait-based approach to examining prey selection by Indo-Pacific lionfish (Pterois volitans and Pterois miles), invasive predators that prey upon species-rich reef fish communities and are rapidly spreading across the western Atlantic. We first generate hypotheses about morphological and behavioural traits recurring across fish species that could facilitate or deter predation by lionfish. Constructing generalized linear mixed-effects models that account for relatedness among prey taxa, we test whether these traits predict patterns of diet selection by lionfish within two independent data sets collected at different spatial scales: (i) in situ visual observations of prey consumption and availability for individual lionfish and (ii) comparisons of prey abundance in lionfish stomach contents to availability on invaded reefs at large. Both analyses reveal that a number of traits predicted to affect vulnerability to predation, including body size, body shape, position in the water column and aggregation behaviour, are important determinants of diet selection by lionfish. Small, shallow-bodied, solitary fishes found resting on or just above reefs are the most vulnerable. Fishes that exhibit parasite cleaning behaviour experience a significantly lower risk of predation than non-cleaning fishes, and fishes that are nocturnally active are at significantly greater risk. Together, vulnerable traits heighten the risk of predation by a factor of nearly 200. Our study reveals that a trait-based approach yields insights into predator-prey interactions that are robust across prey assemblages. Importantly, in situ observations of selection yield similar results to broadscale comparisons of prey use and availability, which are more typically gathered for predator species. A trait-based approach could therefore be of use across predator species and ecosystems to predict the outcomes of changing predator-prey interactions on community dynamics.
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Peces/anatomía & histología , Peces/fisiología , Cadena Alimentaria , Actividad Motora , Conducta Predatoria , Animales , Bahamas , Arrecifes de Coral , Dieta , Especies Introducidas , Perciformes/fisiologíaRESUMEN
Trait-based frameworks are increasingly used for predicting how ecological communities respond to ongoing global change. As species range shifts result in novel encounters between predators and prey, identifying prey 'guilds', based on a suite of shared traits, can distill complex species interactions, and aid in predicting food web dynamics. To support advances in trait-based research in open-ocean systems, we present the Pelagic Species Trait Database, an extensive resource documenting functional traits of 529 pelagic fish and invertebrate species in a single, open-source repository. We synthesized literature sources and online resources, conducted morphometric analysis of species images, as well as laboratory analyses of trawl-captured specimens to collate traits describing 1) habitat use and behavior, 2) morphology, 3) nutritional quality, and 4) population status information. Species in the dataset primarily inhabit the California Current system and broader NE Pacific Ocean, but also includes pelagic species known to be consumed by top ocean predators from other ocean basins. The aim of this dataset is to enhance the use of trait-based approaches in marine ecosystems and for predator populations worldwide.
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Ecosistema , Cadena Alimentaria , Animales , Peces , Biología Marina , Océano PacíficoRESUMEN
Parasites, by definition, have a negative effect on their host. However, in wild mammal health and conservation research, sub-lethal infections are commonly assumed to have negligible health effects unless parasites are present in overwhelming numbers. Here, we propose a definition for host health in mammals that includes sub-lethal effects of parasites on the host's capacity to adapt to the environment and maintain homeostasis. We synthesized the growing number of studies on helminth parasites in mammals to assess evidence for the relative magnitude of sub-lethal effects of infection across mammal taxa based on this expanded definition. Specifically, we develop and apply a framework for organizing disparate metrics of parasite effects on host health and body condition according to their impact on an animal's energetic condition, defined as the energetic burden of pathogens on host physiological and behavioural functions that relate directly to fitness. Applying this framework within a global meta-analysis of helminth parasites in wild, laboratory and domestic mammal hosts produced 142 peer-reviewed studies documenting 599 infection-condition effects. Analysing these data within a multiple working hypotheses framework allowed us to evaluate the relative weighted contribution of methodological (study design, sampling protocol, parasite quantification methods) and biological (phylogenetic relationships and host/parasite life history) moderators to variation in the magnitude of health effects. We found consistently strong negative effects of infection on host energetic condition across taxonomic groups, with unusually low heterogeneity in effect sizes when compared with other ecological meta-analyses. Observed effect size was significantly lower within cross-sectional studies (i.e. observational studies that investigated a sub-set of a population at a single point in time), the most prevalent methodology. Furthermore, opportunistic sampling led to a weaker negative effect compared to proactive sampling. In the model of host taxonomic group, the effect of infection on energetic condition in carnivores was not significant. However, when sampling method was included, it explained substantial inter-study variance; proactive sampling showing a strongly significant negative effect while opportunistic sampling detected only a weak, non-significant effect. This may partly underlie previous assumptions that sub-lethal parasites do not have significant effects on host health. We recommend future studies adopt energetic condition as the framework for assessing parasite effects on wildlife health and provide guidelines for the selection of research protocols, health proxies, and relating infection to fitness.
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Carnívoros , Helmintos , Parásitos , Animales , Estudios Transversales , Helmintos/fisiología , Interacciones Huésped-Parásitos/fisiología , Mamíferos , FilogeniaRESUMEN
BACKGROUND: Tamoxifen is standard adjuvant treatment for postmenopausal women with hormone-receptor-positive breast cancer. We assessed the benefit of adding chemotherapy to adjuvant tamoxifen and whether tamoxifen should be given concurrently or after chemotherapy. METHODS: We undertook a phase 3, parallel, randomised trial (SWOG-8814, INT-0100) in postmenopausal women with hormone-receptor-positive, node-positive breast cancer to test two major objectives: whether the primary outcome, disease-free survival, was longer with cyclophosphamide, doxorubicin, and fluorouracil (CAF) given every 4 weeks for six cycles plus 5 years of daily tamoxifen than with tamoxifen alone; and whether disease-free survival was longer with CAF followed by tamoxifen (CAF-T) than with CAF plus concurrent tamoxifen (CAFT). Overall survival and toxicity were predefined, important secondary outcomes for each objective. Patients in this open-label trial were randomly assigned by a computer algorithm in a 2:3:3 ratio (tamoxifen:CAF-T:CAFT) and analysis was by intention to treat of eligible patients. Groups were compared by stratified log-rank tests, followed by Cox regression analyses adjusted for significant prognostic factors. This trial is registered with ClinicalTrials.gov, number NCT00929591. FINDINGS: Of 1558 randomised women, 1477 (95%) were eligible for inclusion in the analysis. After a maximum of 13 years of follow-up (median 8.94 years), 637 women had a disease-free survival event (tamoxifen, 179 events in 361 patients; CAF-T, 216 events in 566 patients; CAFT, 242 events in 550 patients). For the first objective, therapy with the CAF plus tamoxifen groups combined (CAFT or CAF-T) was superior to tamoxifen alone for the primary endpoint of disease-free survival (adjusted Cox regression hazard ratio [HR] 0.76, 95% CI 0.64-0.91; p=0.002) but only marginally for the secondary endpoint of overall survival (HR 0.83, 0.68-1.01; p=0.057). For the second objective, the adjusted HRs favoured CAF-T over CAFT but did not reach significance for disease-free survival (HR 0.84, 0.70-1.01; p=0.061) or overall survival (HR 0.90, 0.73-1.10; p=0.30). Neutropenia, stomatitis, thromboembolism, congestive heart failure, and leukaemia were more frequent in the combined CAF plus tamoxifen groups than in the tamoxifen-alone group. INTERPRETATION: Chemotherapy with CAF plus tamoxifen given sequentially is more effective adjuvant therapy for postmenopausal patients with endocrine-responsive, node-positive breast cancer than is tamoxifen alone. However, it might be possible to identify some subgroups that do not benefit from anthracycline-based chemotherapy despite positive nodes. FUNDING: National Cancer Institute (US National Institutes of Health).
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Adenocarcinoma/tratamiento farmacológico , Antineoplásicos Hormonales/administración & dosificación , Neoplasias de la Mama/tratamiento farmacológico , Ganglios Linfáticos/patología , Tamoxifeno/administración & dosificación , Adenocarcinoma/mortalidad , Adulto , Anciano , Antibióticos Antineoplásicos/administración & dosificación , Antimetabolitos Antineoplásicos/administración & dosificación , Antineoplásicos Alquilantes/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias de la Mama/mortalidad , Quimioterapia Adyuvante , Ciclofosfamida/administración & dosificación , Supervivencia sin Enfermedad , Doxorrubicina/administración & dosificación , Femenino , Fluorouracilo/administración & dosificación , Humanos , Metástasis Linfática , Persona de Mediana Edad , Posmenopausia , Receptores de Estrógenos/análisis , Receptores de Progesterona/análisisAsunto(s)
Microesferas , Plásticos , Contaminantes Químicos del Agua/análisis , Contaminación del Agua , Política Ambiental/legislación & jurisprudencia , Humanos , Contaminantes Químicos del Agua/química , Contaminación del Agua/análisis , Contaminación del Agua/prevención & control , Contaminación del Agua/estadística & datos numéricosRESUMEN
PURPOSE: We evaluated the efficacy of cyclophosphamide, methotrexate, and fluorouracil (CMF) versus cyclophosphamide, doxorubicin, and fluorouracil (CAF) in node-negative breast cancer patients with and without tamoxifen (TAM), overall and by hormone receptor (HR) status. PATIENTS AND METHODS: Node-negative patients identified by tumor size (> 2 cm), negative HR, or high S-phase fraction (n = 2,690) were randomly assigned to CMF, CAF, CMF + TAM (CMFT), or CAF + TAM (CAFT). Cox regression evaluated overall survival (OS) and disease-free survival (DFS) for CAF versus CMF and TAM versus no TAM separately. Two-sided CIs and one-sided P values for planned comparisons were calculated. RESULTS: Ten-year estimates indicated that CAF was not significantly better than CMF (P = .13) for the primary outcome of DFS (77% v 75%; HR = 1.09; 95% CI, 0.94 to 1.27). CAF had slightly better OS than CMF (85% v 82%, HR = 1.19 for CMF v CAF; 95% CI, 0.99 to 1.43); values were statistically significant in the planned one-sided test (P = .03). Toxicity was greater with CAF and did not increase with TAM. Overall, TAM had no benefit (DFS, P = .16; OS, P = .37), but the TAM effect differed by HR groups. For HR-positive patients, TAM was beneficial (DFS, HR = 1.32 for no TAM v TAM; 95% CI, 1.09 to 1.61; P = .003; OS, HR = 1.26; 95% CI, 0.99 to 1.61; P = .03), but not for HR-negative patients (DFS, HR = 0.81 for no TAM v TAM; 95% CI, 0.64 to 1.03; OS, HR = 0.79; 95% CI, 0.60 to 1.05). CONCLUSION: CAF did not improve DFS compared with CMF; there was a slight effect on OS. Given greater toxicity, we cannot conclude CAF to be superior to CMF. TAM is effective in HR-positive disease, but not in HR-negative disease.
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Protocolos de Quimioterapia Combinada Antineoplásica/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Neoplasias de la Mama/patología , Ciclofosfamida/administración & dosificación , Supervivencia sin Enfermedad , Doxorrubicina/administración & dosificación , Femenino , Fluorouracilo/administración & dosificación , Humanos , Metotrexato/administración & dosificación , Persona de Mediana Edad , Modelos de Riesgos Proporcionales , Estudios Prospectivos , Análisis de Supervivencia , Tamoxifeno/administración & dosificaciónRESUMEN
PURPOSE: Theoretical considerations and clinical experience suggest that dose-dense chemotherapy may be superior to other approaches using the same drugs. We studied a dose-dense combination of doxorubicin and cyclophosphamide, with or without fluorouracil, as adjuvant therapy. PATIENTS AND METHODS: Patients with resected breast cancer were treated if they were node-positive and estrogen receptor-negative, positive for overexpression of Her-2-neu, or had four or more involved nodes. Doxorubicin was given weekly to a total dose of 480 mg/m(2). Cyclophosphamide 60 mg/m(2) was given daily by mouth during the period of doxorubicin treatment. The first 30 patients received fluorouracil at 300 mg/m(2)/wk intravenously concurrently with doxorubicin administration. In the last 22, it was omitted because of symptomatic hand-foot syndrome in the majority of patients. Filgrastim (granulocyte colony-stimulating factor [G-CSF]) was administered during chemotherapy every day except the day of intravenous administration and continued until 1 week after the completion of the chemotherapy. RESULTS: Between October 20, 1992, and June 10, 1997, we enrolled 52 patients. The mean delivered dose-intensity for doxorubicin was 18.6 mg/m(2)/wk. Hospitalization was required in 6% of patients for reversible febrile neutropenia. There were no acute treatment-related deaths, but one patient subsequently died of acute leukemia with a characteristic translocation for anthracycline-related exposure. At 5 years, the event-free survival was 86% for all patients (95% confidence interval, 75% to 95%). CONCLUSION: Continuous dose-dense chemotherapy with G-CSF support produced encouraging results, which seem to be superior to those expected with "standard" doxorubicin and cyclophosphamide chemotherapy. It deserves a test in the form of a randomized trial where this approach to anthracycline-based treatment is compared with intermittent administration.
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Antibióticos Antineoplásicos/administración & dosificación , Protocolos de Quimioterapia Combinada Antineoplásica/administración & dosificación , Neoplasias de la Mama/tratamiento farmacológico , Doxorrubicina/administración & dosificación , Adulto , Protocolos de Quimioterapia Combinada Antineoplásica/efectos adversos , Neoplasias de la Mama/mortalidad , Neoplasias de la Mama/patología , Quimioterapia Adyuvante , Ciclofosfamida/administración & dosificación , Supervivencia sin Enfermedad , Esquema de Medicación , Femenino , Fluorouracilo/administración & dosificación , Humanos , Metástasis Linfática , Persona de Mediana Edad , Tasa de Supervivencia , Estados Unidos/epidemiologíaRESUMEN
PURPOSE: Preclinical data indicate that expression of the ErbB family of receptors, such as HER-2 and HER-1 (EGFR) may be involved in endocrine resistance. Evidence of resistance from clinical studies has been inconsistent. The present study examined whether HER-2 gene amplification or HER-1 expression predicted response to tamoxifen. PATIENTS AND METHODS: Three hundred and forty nine patients had estrogen receptor (ER)-positive breast cancer and received daily tamoxifen as initial therapy for advanced disease. HER-2 gene amplification, detected by fluorescence in situ hybridization, and HER-1 expression, evaluated by immunohistochemistry, was determined on 136 and 204 patients, respectively. RESULTS: HER-2 amplification was correlated with lower ER (P = 0.02), HER-1 positivity (P = 0.004), and HER-2 protein overexpression (P < 0.00001). The response rate was 56% for HER-2 non-amplified versus 47% for HER-2 amplified tumors (P = 0.38), and 58% for HER-1-negative versus 36% for HER-1-positive (P = 0.05). Time to treatment failure (TTF) was 7 months for non-amplified HER-2 tumors and 5 months (P = 0.007) for amplified HER-2 tumors, and there was a trend toward a better overall survival (OS) in patients with non-amplified HER-2 tumors (median 31 versus 25 months, respectively, P = 0.07). For positive versus negative HER-1 tumors, TTF was 4 versus 8 months (P = 0.08) and median survival was 24 versus 31 months (P = 0.41). Combining HER-1 expression and HER-2 gene status, patients with both negative HER-1 expression and non-amplified HER-2 had longer TTF (P = 0.001) and OS (P = 0.03) than if either were positive. In multivariate analysis, HER-2 was not an independent factor for TTF and OS, although HER-1 was significant for TTF only (P = 0.001). CONCLUSION: Patients with HER-2 amplification and HER-1 expression had lower ER levels and were modestly less responsive to tamoxifen, suggesting that molecular events in addition to those involving the ErbB receptors are important in determining the endocrine-resistant phenotype.
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Antineoplásicos Hormonales/uso terapéutico , Neoplasias de la Mama/tratamiento farmacológico , Receptores ErbB/metabolismo , Amplificación de Genes , Receptor ErbB-2/genética , Receptores de Estrógenos/metabolismo , Tamoxifeno/uso terapéutico , Anciano , Neoplasias de la Mama/metabolismo , Receptores ErbB/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Humanos , Técnicas para Inmunoenzimas , Hibridación Fluorescente in Situ , Neoplasias Hormono-Dependientes/tratamiento farmacológico , Neoplasias Hormono-Dependientes/metabolismo , Premenopausia , Receptor ErbB-2/metabolismo , Tasa de Supervivencia , Factores de Tiempo , Resultado del TratamientoRESUMEN
Information on fish movement and growth is primarily obtained through the marking and tracking of individuals with external tags, which are usually affixed to anesthetized individuals at the surface. However, the quantity and quality of data obtained by this method is often limited by small sample sizes owing to the time associated with the tagging process, high rates of tagging-related mortality, and displacement of tagged individuals from the initial capture location. To address these issues, we describe a technique for applying external streamer and dart tags in situ, which uses SCUBA divers to capture and tag individual fish on the sea floor without the use of anesthetic. We demonstrate this method for Indo-Pacific lionfish (Pterois volitans/P. miles), species which are particularly vulnerable to barotrauma when transported to and handled at the surface. To test our method, we tagged 161 individuals inhabiting 26 coral reef locations in the Bahamas over a period of 3 years. Our method resulted in no instances of barotrauma, reduced handling and recovery time, and minimal post-tagging release displacement compared with conventional ex situ tag application. Opportunistic resighting and recapture of tagged individuals reveals that lionfish exhibit highly variable site fidelity, movement patterns, and growth rates on invaded coral reef habitats. In total, 24% of lionfish were resighted between 29 and 188 days after tagging. Of these, 90% were located at the site of capture, while the remaining individuals were resighted between 200 m and 1.1 km from initial site of capture over 29 days later. In situ growth rates ranged between 0.1 and 0.6 mm/day. While individuals tagged with streamer tags posted slower growth rates with increasing size, as expected, there was no relationship between growth rate and fish size for individuals marked with dart tags, potentially because of large effects of tag presence on the activities of small bodied lionfish (i.e., <150 mm), where the tag was up to 7.6% of the lionfish's mass. Our study offers a novel in situ tagging technique that can be used to provide critical information on fish site fidelity, movement patterns, and growth in cases where ex situ tagging is not feasible.
RESUMEN
Biotic resistance is the idea that native species negatively affect the invasion success of introduced species, but whether this can occur at large spatial scales is poorly understood. Here we re-evaluated the hypothesis that native large-bodied grouper and other predators are controlling the abundance of exotic lionfish (Pterois volitans/miles) on Caribbean coral reefs. We assessed the relationship between the biomass of lionfish and native predators at 71 reefs in three biogeographic regions while taking into consideration several cofactors that may affect fish abundance, including among others, proxies for fishing pressure and habitat structural complexity. Our results indicate that the abundance of lionfish, large-bodied grouper and other predators were not negatively related. Lionfish abundance was instead controlled by several physical site characteristics, and possibly by culling. Taken together, our results suggest that managers cannot rely on current native grouper populations to control the lionfish invasion.
RESUMEN
As a result of being hunted, animals often alter their behaviour in ways that make future encounters with predators less likely. When hunting is carried out for conservation, for example to control invasive species, these behavioural changes can inadvertently impede the success of future efforts. We examined the effects of repeated culling by spearing on the behaviour of invasive predatory lionfish (Pterois volitans/miles) on Bahamian coral reef patches. We compared the extent of concealment and activity levels of lionfish at dawn and midday on 16 coral reef patches off Eleuthera, The Bahamas. Eight of the patches had been subjected to regular daytime removals of lionfish by spearing for two years. We also estimated the distance at which lionfish became alert to slowly approaching divers on culled and unculled reef patches. Lionfish on culled reefs were less active and hid deeper within the reef during the day than lionfish on patches where no culling had occurred. There were no differences at dawn when removals do not take place. Lionfish on culled reefs also adopted an alert posture at a greater distance from divers than lionfish on unculled reefs. More crepuscular activity likely leads to greater encounter rates by lionfish with more native fish species because the abundance of reef fish outside of shelters typically peaks at dawn and dusk. Hiding deeper within the reef could also make remaining lionfish less likely to be encountered and more difficult to catch by spearfishers during culling efforts. Shifts in the behaviour of hunted invasive animals might be common and they have implications both for the impact of invasive species and for the design and success of invasive control programs.
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Especies Introducidas , Perciformes , Conducta Predatoria , Animales , Bahamas , Arrecifes de Coral , Ecosistema , Islas , OceanografíaRESUMEN
Biotic resistance, the process by which new colonists are excluded from a community by predation from and/or competition with resident species, can prevent or limit species invasions. We examined whether biotic resistance by native predators on Caribbean coral reefs has influenced the invasion success of red lionfishes (Pterois volitans and Pterois miles), piscivores from the Indo-Pacific. Specifically, we surveyed the abundance (density and biomass) of lionfish and native predatory fishes that could interact with lionfish (either through predation or competition) on 71 reefs in three biogeographic regions of the Caribbean. We recorded protection status of the reefs, and abiotic variables including depth, habitat type, and wind/wave exposure at each site. We found no relationship between the density or biomass of lionfish and that of native predators. However, lionfish densities were significantly lower on windward sites, potentially because of habitat preferences, and in marine protected areas, most likely because of ongoing removal efforts by reserve managers. Our results suggest that interactions with native predators do not influence the colonization or post-establishment population density of invasive lionfish on Caribbean reefs.
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Arrecifes de Coral , Ecosistema , Peces/fisiología , Conducta Predatoria/fisiología , Animales , Biomasa , Región del Caribe , Densidad de Población , Dinámica PoblacionalRESUMEN
Indo-Pacific lionfish (Pterois volitans and P. miles) have spread swiftly across the Western Atlantic, producing a marine predator invasion of unparalleled speed and magnitude. There is growing concern that lionfish will affect the structure and function of invaded marine ecosystems, however detrimental impacts on natural communities have yet to be measured. Here we document the response of native fish communities to predation by lionfish populations on nine coral reefs off New Providence Island, Bahamas. We assessed lionfish diet through stomach contents analysis, and quantified changes in fish biomass through visual surveys of lionfish and native fishes at the sites over time. Lionfish abundance increased rapidly between 2004 and 2010, by which time lionfish comprised nearly 40% of the total predator biomass in the system. The increase in lionfish abundance coincided with a 65% decline in the biomass of the lionfish's 42 Atlantic prey fishes in just two years. Without prompt action to control increasing lionfish populations, similar effects across the region may have long-term negative implications for the structure of Atlantic marine communities, as well as the societies and economies that depend on them.
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Peces , Especies Introducidas , Conducta Predatoria , Animales , Bahamas , Biomasa , Arrecifes de Coral , Ecosistema , Océanos y Mares , Dinámica PoblacionalRESUMEN
PURPOSE: Prior progestin studies treating hot flashes in women have been short duration and single dose. This study tests the progestin megestrol acetate (MA) at two doses versus placebo over 6 months. PATIENTS AND METHODS: Patients with T1-3, N0-1, M0 breast cancer were eligible after completion of surgery and chemotherapy and at least 4 months of tamoxifen (if prescribed). Women were required to have at least 10 hot flashes of any severity or at least five severe episodes per week. Patients were randomly assigned to placebo, MA 20 mg, or MA 40 mg for 3 months. Success at 3 months was defined as completion of treatment with a >or= 75% reduction in hot flashes from baseline. If success was achieved, drug treatment for another 3 months was given on the same blinded arm; if not, open-label MA 20 mg was added to blinded study drug and continued for 3 months. Other menopausal symptoms were also assessed. RESULTS: Two hundred eighty eight eligible women were randomly assigned (286 eligible), of whom 85% were on tamoxifen, 40% had over 63 hot flashes/week, and 75% had vasomotor symptoms for >or= 6 months. Success at 3 months was 14% on placebo, 65% on 20 mg, and 48% on 40 mg (both MA doses superior to placebo; P < .0001). Most successes at 3 months were maintained at 6 months (77% on 20 mg and 81% on 40 mg). CONCLUSION: MA significantly reduced vasomotor symptoms with durable benefit over 6 months. MA 20 mg/d is the preferred dose. There was no significant impact on other menopausal symptoms.