Antifouling activity of seaweed extracts from Guarujá, São Paulo, Brazil

A incrustação biológica constitui, historicamente, um dos maiores problemas encontrados pelo homem em suas atividades no mar. A busca por alternativas a tintas antiincrustantes contendo tributilestanho (TBT) tem levado diversos pesquisadores a concentrar esforços no desenvolvimento de substâncias naturais menos danosas à biota marinha. Este trabalho procurou contribuir com essa busca, testando o potencial antiincrustante de quatro diferentes espécies de macroalgas da Praia Branca, município de Guarujá, SP. Através de testes antiincrustantes em laboratório utilizando a fixação de um organismo incrustante comum, o mexilhão Perna perna, foi constatado que os extratos de Jania rubens (Rhodophyta, Cryptonemiales) e Bryothamnion seaforthii (Rhodophyta, Ceramiales), à concentração natural, apresentaram atividade antiincrustante significativa (p < 0,05), enquanto Dictyopteris delicatula (Phaeophyta, Dictyotales) e Heterosiphonia gibbesii (Rhodophyta, Ceramiales) não demonstraram eficiência na inibição da fixação de bissos do molusco. Das algas que indicaram potencial atividade contra a incrustação, J. rubens apresentou melhor desempenho em relação a B. seaforthii. Futuras investigações em campo serão necessárias para a obtenção de resultados que possam refletir melhor as condições naturais, bem como avaliar o espectro de ação da atividade antiincrustante observada. A purificação guiada por bioensaios dos extratos ativos poderá levar a novas alternativas para os antiincrustantes metálicos atualmente em uso.Marine biofouling historically constitutes one of the major constraints faced by mankind in its oceanic activities. The search for alternatives to TBT-based antifouling paints has led several researchers to focus efforts in the development of environmentally friendly natural compounds. This work has contributed with this search, testing the antifouling potential of crude organic extracts from four seaweed species collected at Praia Branca, Guarujá district, São Paulo, Brazil. Throughout laboratory antifouling assays in which the attachment of a common fouling organism, the brown mussel Perna perna, was employed, antifouling activity (p < 0.05) was detected in natural concentrations of the extracts of Jania rubens (Rhodophyta, Cryptonemiales) and Bryothamnion seaforthii (Rhodophyta, Ceramiales), while Dictyopteris delicatula (Phaeophyta, Dictyotales) and Heterosiphonia gibbesii (Rhodophyta, Ceramiales) did not exhibit fouling inhibition. From the algae that exhibited antifouling activity, J. rubens presented best performance when compared to that of B. seaforthii. Future field studies would be necessary to obtain results that can better reflect natural conditions, as well as to assess the activity spectrum of the antifouling activity presently recorded. Further bioassay-guided purification of the active extracts can lead to new alternatives to the metal-based antifouling paints currently in use

Effects of disturbance area on fouling communities from a tropical environment: Guanabara Bay, Rio de Janeiro, Brazil

Em comunidades incrustantes marinhas, o espaço livre no substrato é um dos principais recursos limitantes para o estabelecimento de novos organismos. Assim sendo, distúrbios físicos que removam biomassa se mostram importantes agentes para a estruturação e dinâmica dessas comunidades. A extensão do distúrbio é uma característica que parece afetar os padrões de recolonização, e desta forma altera a diversidade de espécies. O objetivo deste trabalho foi analisar os efeitos de áreas crescentes de distúrbio em comunidades incrustantes. Para tal, comunidades macrobentônicas incrustantes foram previamente desenvolvidas por 6 meses na Baía de Guanabara (22°52'S, 043°08'W), recebendo uma única vez distúrbios circulares, aleatoriamente posicionados, com áreas crescentes (7 níveis, de 0 a 75% da cobertura removida, 10 réplicas por nível). Amostragens quinzenais foram realizadas após o distúrbio, de modo a acompanhar os padrões de desenvolvimento das comunidades. Na primeira amostragem observou-se que índices máximos de diversidade foram obtidos nas comunidades que receberam níveis intermediários de distúrbio. No entanto, no decorrer do tempo este perfil deu lugar a um pico de diversidade nas comunidades que sofreram os maiores níveis de distúrbio. Notou-se também um incremento contínuo da riqueza e diversidade ao longo do tempo até a 7ª amostragem (110 dias após os distúrbios), com subseqüente redução a partir deste momento. Tais padrões parecem corroborar a Hipótese do Distúrbio Intermediário, embora em médio prazo o perfil da comunidade mude drasticamente, revelando que perturbações físicas representam de fato um importante fator na estruturação de comunidades marinhas de substrato consolidado da Baía de Guanabara, além de realçar a importância de estudos de maior duração na avaliação dos impactos de distúrbios em comunidades marinhas.In marine fouling communities, free space is one of the key limiting resources for settlement of new organisms. In this way, removing biomass through physical disturbances would play an important role in the structure and dynamics of these communities. The disturbance size seems to be a characteristic that influences recolonization patterns, thus affecting species diversity. The aim of this study was to analyze the effects of growing disturbance areas on fouling communities. Fouling panels were allowed to develop for 6 mo. at Guanabara Bay (22°52'S, 043°08'W) prior to a single application of randomly positioned, circular physical disturbances of growing areas (7 levels, from 0 to 75% removed cover, 10 replicates per treatment). Samples were taken fortnightly after the disturbance event, so as to follow the development patterns of the community afterward. At the first sampling the diversity showed maximum indices in communities to which intermediary disturbance levels were applied. However, this profile changed later to a diversity peak in communities with higher disturbance levels. It also showed a continuous increase in richness and diversity through time until the 7th sample (110 days after the disturbance event), with subsequent decrease. Such patterns seem to corroborate the Intermediate Disturbance Hypothesis, despite the drastic profile change with time, revealing that disturbance is indeed an important factor structuring hard bottom communities at Guanabara Bay, and highlighting the importance of longer term studies of disturbance impacts in marine communities

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Effects of disturbance area on fouling communities from a tropical environment: Guanabara Bay, Rio de Janeiro, Brazil

In marine fouling communities, free space is one of the key limiting resources for settlement of new organisms. In this way, removing biomass through physical disturbances would play an important role in the structure and dynamics of these communities. The disturbance size seems to be a characteristic that influences recolonization patterns, thus affecting species diversity. The aim of this study was to analyze the effects of growing disturbance areas on fouling communities. Fouling panels were allowed to develop for 6 mo. at Guanabara Bay (22°52'S, 043°08'W) prior to a single application of randomly positioned, circular physical disturbances of growing areas (7 levels, from 0 to 75% removed cover, 10 replicates per treatment). Samples were taken fortnightly after the disturbance event, so as to follow the development patterns of the community afterward. At the first sampling the diversity showed maximum indices in communities to which intermediary disturbance levels were applied. However, this profile changed later to a diversity peak in communities with higher disturbance levels. It also showed a continuous increase in richness and diversity through time until the 7th sample (110 days after the disturbance event), with subsequent decrease. Such patterns seem to corroborate the Intermediate Disturbance Hypothesis, despite the drastic profile change with time, revealing that disturbance is indeed an important factor structuring hard bottom communities at Guanabara Bay, and highlighting the importance of longer term studies of disturbance impacts in marine communities