Bottom trawling threatens future climate refugia of rhodoliths globally

Climate driven range shifts are driving the redistribution of marine species and threatening the functioning and stability of marine ecosystems. For species that are the structural basis of marine ecosystems, such effects can be magnified into drastic loss of ecosystem functioning and resilience. Rhodoliths are unattached calcareous red algae that provide key complex three-dimensional habitats for highly diverse biological communities. These globally distributed biodiversity hotspots are increasingly threatened by ongoing environmental changes, mainly ocean acidification and warming, with wide negative impacts anticipated in the years to come. These are superimposed upon major local stressors caused by direct destructive impacts, such as bottom trawling, which act synergistically in the deterioration of the rhodolith ecosystem health and function. Anticipating the potential impacts of future environmental changes on the rhodolith biome may inform timely mitigation strategies integrating local effects of bottom trawling over vulnerable areas at global scales. This study aimed to identify future climate refugia, as regions where persistence is predicted under contrasting climate scenarios, and to analyze their trawling threat levels. This was approached by developing species distribution models with ecologically relevant environmental predictors, combined with the development of a global bottom trawling intensity index to identify heavily fished regions overlaying rhodoliths. Our results revealed the importance of light, thermal stress and pH driving the global distribution of rhodoliths. Future projections showed poleward expansions and contractions of suitable habitats at lower latitudes, structuring cryptic depth refugia, particularly evident under the more severe warming scenario RCP 8.5. Our results suggest that if management and conservation measures are not taken, bottom trawling may directly threaten the persistence of key rhodolith refugia. Since rhodoliths have slow growth rates, high sensitivity and ecological importance, understanding how their current and future distribution might be susceptible to bottom trawling pressure, may contribute to determine the fate of both the species and their associated communities.FCT: UIDB/04326/2020/ PTDC/BIA-CBI/6515/2020/ SFRH/BD/144878/2019/ SFRH/BSAB/150485/2019/ norm-DL57/2016/CP1361/CT0035info:eu-repo/semantics/publishedVersio

A review of common parameters and descriptors used in studies of the impacts of heavy metal pollution on marine macroalgae: identification of knowledge gaps and future needs

This study presents a systematic review to assess the main similarities and gaps in efforts to evaluate the impacts of heavy metals on benthic marine seaweeds. A total of 91 studies were compiled, the main parameters (abiotic, biological, ecotoxicological, and heavy metals) and descriptors of which were evaluated by quantitative and qualitative analyses. Our results indicate the importance of diversifying searches by including different languages (i.e. English, Portuguese and Spanish). Most of the studies were field characterizations, with few abiotic parameters and/or seasonality evaluations being employed. In contrast, the assessment of ecotoxicological parameters was highly frequent, which seems incoherent considering the absence of data to support the use of these results in biomonitoring applications. The genera Sargassum, Ulva and Enteromorpha were widely studied worldwide, apart from a small fraction of studies assessing higher levels of biological organization. Moreover, the use of different parameters and descriptors by the evaluated studies precludes making conclusive or reliable comparisons. These findings highlight the importance of greater efforts to construct a concise baseline of knowledge using similar parameters so that global evaluations of the impacts of heavy metals on photosynthetic organisms can be undertaken.info:eu-repo/semantics/publishedVersio

Phenotypic plasticity in sargassum forests may not counteract projected biomass losses along a broad latitudinal gradient

Phenotypic plasticity and local adaptation can adjust individual responses to environmental changes across species' ranges. Studies addressing the implications of such traits have been underrepresented in the marine environment. Sargassum cymosum represents an ideal model to test phenotypic plasticity, as populations along the southwestern Atlantic Ocean display a sharp decrease in abundance toward distributional range limits. We (1) characterized the macroecological environment of S. cymosum across a latitudinal gradient, (2) evaluated potential differences in ecophysiological adjustments (biomass, photosynthetic pigments, phenolic compounds, total soluble sugars and proteins, and carbon-nitrogen-CN-content), and (3) tested for differences in thermal tolerance based on time series analyses produced from the present to contrasting representative concentration pathways scenarios (RCP) of future climate changes. Our results showed distinct macroecological environments, corresponding to tropical and warm temperate conditions, driving biomass and ecophysiological adjustments of S. cymosum. Populations from the two environments displayed contrasting thermal tolerances, with tropical individuals better coping with thermal stress when compared to more temperate ones (lethal temperatures of 33 degrees C vs. 30 degrees C); yet both populations lose biomass in response to increasing thermal stress while increasing secondary metabolites (for example, carotenoids and phenolic compounds) and decrease chlorophyll's content, Fv/Fm, total soluble sugars concentration and CN ratio, owing to oxidative stress. Despite evidence for phenotypic plasticity, significant future losses might occur in both tropical and warm temperate populations, particularly under the no mitigation RCP scenario, also known as the business as usual (that is, 8.5). In this context, broad compliance with the Paris Agreement might counteract projected impacts of climate change, safeguarding Sargassum forests in the years to come.This study was supported by grants from Boticario Foundation, FAPESC-Foundation Support Research and Innovation in the State of Santa Catarina, Capes Higher Education Personnel Improvement Coordination, CNPq-National Council for Scientific and Technological Development, Petrobras Ambiental, REBENTOS-Habitat monitoring network coastal Benthic and ProspecMar-Islands Sustainable Prospecting in Ocean Islands: Biodiversity, Chemistry, Ecology and Biotechnology, Rede Coral Vivo, REDEALGAS, a Pew Marine Fellowship, the Foundation for Science and Technology (FCT) of Portugal via SFRH/BSAB/150485/2019, SFRH/BD/144878/2019, UID/Multi/04326/2019, PTDC/BIA-CBI/6515/2020 and the transitional norm DL57/2016/CP1361/CT0035. LPG received a doctorate scholarship (88882.438723/2019-01) from Capes. CFDG thanks CNPq grants PQ-309658/2016-0and306304/2019-8. PAH thanks CAPES-Senior Visitor, CAPESPrInt 310793/2018-01, CNPq-PVE 407365/2013-3, CNPq-Universal 426215/2016-8 and CNPq-PQ308537/2019-0. GK received a master's scholarship from CAPES.info:eu-repo/semantics/submittedVersio

Association between virulence factors and antimicrobial resistance from enterotoxigenic escherichia coli isolated from pigs with diarrhea in Brazil

Background: Enterotoxigenic Escherichia coli (ETEC) is the etiologic agent of post weaning colibacillosis, one of the most important diseases in pig farming. The pathogenesis of the disease is associated with two virulence factors (VF), fimbriae and enterotoxins. In veterinary medicine, the use of antibiotics can lead to the selection of resistant bacteria. The association of VF and antibiotic resistance is an important mechanism for bacterial survival under adverse conditions. This study aimed to determine the VF and antimicrobial susceptibility of ETEC isolates from piglets with diarrhea and analyze the association between these factors. Materials, Methods & Results: A total of 185 rectal swabs were collected from weaned piglets in Brazilian farms of the states of Rio Grande do Sul, Santa Catarina, Paraná, Minas Gerais and Goiás. The isolation of ETEC was carried out on blood and MacConkey Agar and characterization by biochemical tests and detection by PCR of fimbrial genes F4, F45, F6, F18 and F41, and toxins genes LT, STa, STb and STx2e. Antimicrobial susceptibility profiles were determined by Agar diffusion test for amoxicillin, ampicillin, ceftiofur, ciprofloxacin, colistin, doxycycline, enrofloxacin, florfenicol, gentamicin, neomycin, norfloxacin, oxytetracycline, streptomycin, tetracycline, lincomycin + spectinomycin and sulfamethoxazole + trimethoprim. The association between VF and antimicrobials resistance results was determined by Chi-square and Fisher test (P ≤ 0.05). A total of 376 isolates were analyzed. The frequencies of fimbriae and toxins amplified were: F4 (31.6%), F18 (18.9%), F5 (4.2%) and toxins STa (43.1%), STb (24.7%), LT (21.8%) and STx2e (5.3%). Antibiotic resistance was higher to tetracycline (96.3%), florfenicol (95.2%), oxytetracycline (93.62%) and doxycycline (90.7%). Lowest levels of resistance were to ceftiofur (2.1%), colistin (9.8%), lincomycin + spectinomicin (15.4%) and neomycin (23.1%). The association of VF and resistance was significant for fimbriae F4 and streptomycin and sulfamethoxazole + trimethoprim; F5 and enrofloxacin, ciprofloxacin and norfloxacin; F18 and amoxicillin, ampicillin, doxycycline, enrofloxacin, norfloxacin, ciprofloxacin and sulfamethoxazole + trimethoprim. Among the toxins LT and tetracycline, streptomycin and florfenicol; STa and amoxicillin, ampicillin, oxytetracycline, enrofloxacin and sulfamethoxazole + trimethoprim; STb and colistin and streptomycin. Discussion: Resistance to all antimicrobials was observed, with higher levels for tetracyclines and lower to ceftiofur and lincomycin + spectinomycin. Several studies have reported ETEC virotype variation which can be influenced by management differences in pig farms. The presence of VF and acquisition of antimicrobial resistance mechanisms might be related to evolutionary factors, infection pressure and intensive use of antibiotics. E. coli is considered one of the most versatile bacterial species and its diversity in adaptability is due to its genomic plasticity, influencing the capacity to colonize numerous host species. This is possible by mechanisms such as gain or loss of genes through lateral transfer of plasmids, transposons and integrons, which vary regarding the environment to which they are exposed. More studies are needed to correlate genetically the interaction of antimicrobial resistance and virulence genes to elucidate if the virulence expression is affected by chromosomal mutations that lead to specific resistance or/ and both determinants are inserted into the same mobile genetic element, such as a conjugative plasmid

Da fisiologia ao nicho: presente e futuro dos bancos de rodolitos brasileiros

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências Biológicas, Programa de Pós-Graduação em Ecologia, Florianópolis, 2020.As mudanças climáticas já exercem efeito sobre as espécies bentônicas marinhas. Associativamente, impactos locais, como a poluição, interagem e intensificam os efeitos das mudanças climáticas. Observam-se efeitos de mortalidade de espécies-chave e estruturadoras sistêmicas, como as algas calcáreas de vida livre (rodolitos). Frente às ameaças atuais e os cenários futuros para a mudança das condições abióticas, os impactos sobre a fisiologia e a distribuição destes organismos podem acarretar em danos sistêmicos. Portanto, compreender e descrever os principais impactos em escalas global e local aos bancos de rodolitos brasileiros, e investigar quais os efeitos destes para a fisiologia e a adequabilidade de habitat no presente e futuro, é de extrema importância para fomentar decisões de manejo e mitigação destas mudanças. Este estudo é focado em uma importante espécie formadora de rodolitos com ampla distribuição nas províncias biogeográficas brasileiras, o Lithothamnion crispatum (Hauck, 1878), com ampla distribuição nas províncias biogeográficas. A presente dissertação está estruturada em dois capítulos. No primeiro, realizou-se um levantamento dos principais estudos experimentais realizados com espécies de rodolitos, no mundo e no Brasil, verificando-se as forçantes ambientais mais investigadas. Observou-se ausência de experimentos que considerem a interatividade entre estressores e os efeitos de ondas de calor marinhas para as espécies brasileiras, bem como baixa frequência de trabalhos que analisam os efeitos de eutrofização e acidificação oceânica. Assim, realizou-se um experimento para análise da combinação destas três forçantes: aumento repentino de temperaturas (onda de calor marinha), aumento na concentração de nutrientes (eutrofização) e aumento de pCO2 (acidificação oceânica). Foi verificada a resposta no rendimento e na produção fotossintética de L. crispatum após 5 dias de exposição interativa a essas forçantes, e a sua possível recuperação após a remoção desses fatores e restabelecimento das condições iniciais ótimas. Associativamente, um modelo de nicho ecológico foi desenvolvido para determinar que variáveis ambientais explicam a atual distribuição de L. crispatum na costa brasileira, e também para estimar a futura adequabilidade de habitat dessa espécie. L. crispatum sofreu uma grande queda em desempenho fotossintético após 5 dias de exposição às forçantes globais e locais, mas apresentou uma resposta de recuperação após retorno a condições iniciais. Esta inferência experimental está de acordo com os resultados obtidos para o modelo de nicho, que demonstrou que a distribuição da espécie na costa brasileira não é explicada pelos fatores ondas de calor marinha ou pH. Além disso, indicou que, no futuro, pode haver a expansão da adequabilidade de habitat da espécie, ao invés de sua contração, o que seria esperado em um cenário de interações entre estressores. Portanto, L. crispatum aparenta ter uma certa resistência às condições ambientais futuras, porém uma consideração cuidadosa desses resultados precisa ser feita. Isto porque há limitações próprias do estudo e o isolamento destas variáveis. Com a associação futura destas forçantes às mudanças em outros fatores bióticos, como interação com outras espécies, respostas diferenciadas podem ser obtidas, devendo ser avaliadas através de novas modelagens baseadas em dados fisiológicos da espécie nestes cenários interativos.Abstract: Climate change has already affected benthic marine species. Local impacts, such as pollution, interact and intensify the effects of climate change. Mortality of key structuring species is already being observed, such as on species of free-living coralline red algae (rhodoliths). In face of the current threats and future scenarios of environmental change, the impacts on the physiology and distribution of these organisms can result in systemic damages. Therefore, comprehending and describing the main anthropogenic impacts, in local and global scales, to Brazilian rhodolith beds is of extreme importance to inform managing and mitigation actions of these environmental changes. This study is focused in one highly important rhodolithforming species, Lithothamnion crispatum (Hauck, 1878), with a wide distribution across biogeographical provinces. The present thesis is structured in two chapters. In the first, a literature survey was done looking for the main experimental studies developed with rhodolithforming species in Brazil, examining the main environmental drivers investigated. An absence of experiments considering the interaction between these stressors and the effects of marine heatwaves was observed, as well as a low presence of studies analyzing the interaction between eutrophication and ocean acidification. For this reason, in the second chapter, an experiment was run to understand the effects of the combination of three drivers: a sudden increase of temperatures (marine heatwave), increased nutrient concentrations (eutrophication) and increased pCO2 levels (ocean acidification). The physiological response of L. crispatum was evaluated by measurements of photosynthetic production and yield after five days of exposition to the combined drivers, and the possible recovery of individuals after the removal of drivers and return to optimal initial conditions was also measured. Simultaneously, an ecological niche model was developed to determine which environmental variables explain the current distribution of L. crispatum in the Brazilian coast, and the future habitat suitability of this species was also estimated. L. crispatum experienced a great decrease in photosynthetic yield after 5 days of exposition to global and local drivers, but presented a recovery response after returning to the initial conditions. Experiment results are in accordance with model results, which demonstrated that the species? distribution in the Brazilian coast is not determined by heatwaves and pH. Moreover, the ecological niche model showed that in the future, L. crispatum may expand its habitat suitability, instead of losing suitable areas, which was first expected in a scenario of combination of multiple stressors. Therefore, L. crispatum appears to hold a certain resistance to future environmental conditions, although a careful consideration of these results needs to be done, as there as limitations in the study and in the isolation of these variables. With the association of these variables and biotic factors, such as interactions with other species, different responses may be obtained, and must be evaluated through new modeling techniques based in both physiological and biotic data for the species