Influência de Encope emarginata (Leske, 1778) (Echinodermata) sobre a estrutura das associações meiobêntica e microfitobêntica de fundos sublitorais estuarinos

Orientador : Prof. Dr. Paulo da Cunha LanaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Zoologia. Defesa: Curitiba, 22/02/2013Bibliografia : fls. 90-96, 98-99Resumo: Macroinvertebrados bênticos, como a bolacha-do-mar Encope emarginata, perturbam a superfície do sedimento, alterando a complexidade estrutural do habitat, as suas características biogeoquímicas e a disponibilidade de recursos alimentares. Com o intuito de avaliar a influência de Encope emarginata sobre a estrutura das associações microfitobêntica e meiobêntica em regiões sublitorais da Baia de Paranaguá (Paraná, Brasil) este estudo tem como objetivos (1) estimar a densidade e comparar a variabilidade espacial da meiofauna, do microfitobentos e dos parâmetros texturais do sedimento em regiões do sublitoral com a presença de manchas populacionais de E. emarginata vivas (EV), mortas (EM) e sem a presença do equinoide (SE), em distintas escalas espaciais; e (2) avaliar a influência da alimentação e da perturbação biogênica da bolacha-do-mar sobre a estrutura das associações microfitobêntica e meiobêntica de regiões sublitorais estuarinas. Para atender os dois objetivos, o trabalho compreendeu uma abordagem descritiva em campo e um experimento em laboratório, apresentados em distintos capítulos. A densidade total de microalgas e de nematoides foi menor em EV do que nos outros dois tratamentos. Contudo, não observamos diferenças na riqueza de espécies, evidenciando a importância da predação não-seletiva e perturbação biogênica sobre o microfitobentos e a meiofauna. Em contrapartida, a concentração de clorofila-a e a abundância relativa dos comedores de depósito seletivos foram maiores em EV, o que sugere uma influência positiva dos processos de excreção e bioturbação por E. emarginata na oxigenação e difusão de nutrientes, beneficiando a produção microbiana e de microalgas, expressa por maiores biovolumes, aos quais se relacionaram indiretamente os padrões de variação espacial dos grupos tróficos de nematoides. Estas respostas puderam ser parcialmente replicadas em laboratório, demonstrando que os efeitos da perturbação biogênica, causada pela movimentação e alimentação da bolacha-do-mar sobre as associações são relativamente consistentes. Encope emarginata contribui significativamente para aumentar a heterogeneidade ambiental, influenciando decisivamente os padrões de distribuição da meiofauna e do microfitobentos em fundos sublitorais estuarinos. Dessa forma E. emarginata e outras espécies-chave podem contribuir diretamente para a manutenção da biodiversidade e funcionamento do sistema bêntico.Abstract: Benthic macroinvertebrates, such as the sand dollar Encope emarginata, can modify the environment and resource availability, by disturbing surface sediments and affecting nutrient fluxes, in a process often called ecosystem engineering. To determine the effects of sand dollar activities on structure of subtidal microphytobenthic and meiobenthic associations, this work: (1) Describes the variations in diversity and density of microphytobenthos, meiobenthos and sediment variables, at distinct hierarchical spatial scales, in areas with live E. emarginata (LE), only skeletons (DE) and without live or dead sand dollars (WE) along the shallow subtidal region (0.5 - 1.5 m of depth) of the Paranaguá Bay (Southern, Brazil); and (2) assesses the trophic and engineering effects of the sand dollar on microphytobenthos and meiobenthos associations. Although no differences were observed in species richness, the total densities of microalgae and nematodes were lower in the LE than in the other two treatments, suggesting that nonselective predation or biogenic disturbance of sediment by sand dollars can directly affect meio- and microphytobenthic associations. Conversely, chlorophyll-a content and the relative abundance of selective deposit feeders were higher in the LE, due to higher microbial and primary production (preferentially epipelic centric diatoms with relatively high cell biovolumes) by positive effect of sediment oxygenation and nutrient diffusion between sediment-water interface as a result of bioturbation and excretion of E. emarginata. These in situ results were replicated successfully under experimental conditions, suggesting causal effects among feeding and biogenic disturbances activities of sand dollar and community structure of associated microalgae and fauna. We conclude that E. emarginata can significantly affect the dynamics of benthic associations by increasing sediment heterogeneity. Thus, keystone species can contribute to biodiversity and ecossytem functioning of benthic system

Habitat Attributes Dictate the Roles of Dispersal and Environmental Filtering on Metacommunity Assembly at Coastal Soft‑Bottom Ecosystems

Tracking the effects of habitat attributes on species distribution is pivotal to the understanding of community assembly across space and time. We used the elements of metacommunity (EMS), which evaluates coherence, turnover, and boundary clumping of species, to access the spatial patterns of nematodes from three coastal habitats with increasing degree to wave exposure, namely, mangroves, estuarine unvegetated tidal flats, and sandy beaches. Each habitat was sampled in four locations, hundreds of kilometers apart from each other. We hypothesized that (1) coastal habitats act as metacommunity boundaries and drive positive turnover and clumped distribution of species and (2) metacommunity structure within coastal habitats depends on the habitats’ degree to wave exposure since wave energy generally decreases sediment heterogeneity and favors connectivity among locations. Habitats were the main drivers of species turnover, with tidal flats harboring a transitional assemblage between mangrove and sandy beach. Metacommunities from the different habitats showed distinct patterns of organization among locations. Mangroves were characterized by species loss, with smaller areas of mangroves harboring a subset of the species pool present on larger areas of mangroves. Tidal flats showed positive species turnover among the different estuaries, with co-occurring species responding as a group to environmental variations. Both patterns indicate environmental filtering as the main driver at these less wave-exposed habitats. At sandy beaches, in contrast, metacommunity displayed a random pattern, suggesting high connectivity among locations. Our study confirmed that habitat attributes may induce distinct mechanisms of metacommunity assembly at coastal soft-bottom ecosystems.publishedVersio

Migração vertical de nematóides durante um ciclo de maré em um baixio subtropical.

Orientador : Prof. Dr. Paulo da Cunha LanaMonografia (graduação) - Universidade Federal do Paraná, Setor de Ciências da Terra, Centro de Estudos do Mar, Curso de OceanografiaA ocorrência da meiofauna marinha está normalmente restrita às camadas superficiais do sedimento. No entanto, espécies de nematóides podem apresentar uma distribuição vertical profunda. Para avaliar os processos de distribuição vertical desses animais, realizamos um experimento no Baixio dos Papagaios, no setor euhalino do Complexo Estuarino de Paranaguá, partindo da hipótese de que as alterações ambientais causadas pelo tempo relativo de exposição contribuem de maneira significativa para a migração dos nematóides no sedimento e que esta capacidade de migração está relacionada com os comportamentos de alimentação e movimentação, por sua vez condicionados pela morfologia do corpo. Coletamos quatro réplicas com corers de 2,5 cm de diâmetro até a profundidade de 5 cm seccionadas em estratos de 0,5 cm em cada uma de três áreas de 1 m2 definidas de forma aleatória. Relacionamos as variações na distribuição vertical da abundância de nematóides e da concentração de clorofila-a com alterações no substrato durante quatro tempos distintos de um ciclo de maré misto semidiurno (T1, submerso, período imediatamente antes da exposição; T2, emerso, duas horas após T1; T3, emerso, quatro horas após T1; T4, submerso seis horas após T1, no inicio da maré enchente). Apesar de diferenças significativas na densidade de nematóides, o padrão de resposta das espécies foi similar entre áreas. Observamos um padrão geral de migração para camadas mais profundas do sedimento entre T1 e T3, com um aumento da densidade em função da profundidade do sedimento, provavelmente em resposta ao aumento da dessecação e da temperatura. Os padrões de distribuição vertical não diferiram significativamente entre T3 e T4, o que sugere que a força das correntes e o potencial erosivo são estímulos importantes para a migração dos nematóides. As estratégias de alimentação foram determinantes para a distribuição vertical relativa do predador (2B) Viscosia glabra, conhecido por seu comportamento ativo, que migrou em direção ao fundo (p=0,002) provavelmente seguindo suas presas preferenciais. As espécies comedoras de depósito seletivas (1A) Terschellingia longicaudata e Spirinia parasitifera, numericamente dominantes, responderam de maneira distinta à exposição. A primeira é mais ativa e migra para camadas mais profundas (p=0,016), enquanto a segunda, menos ativa, não apresentou movimentação vertical e permaneceu nas camadas subsuperficiais do sedimento (p=0,496). Os resultados apoiam a hipótese testada de que as variações nos parâmetros físico-químicos causadas pelo tempo relativo de emersão e submersão influenciam de forma significativa os padrões de migração vertical. No entanto, estes são igualmente dependentes dos modos de alimentação e fortemente modulados pela capacidade de locomoção das espécies. Palavras chaves: nematóides marinhos, migração vertical, estratégias de alimentação, modos de locomoção, Baia de Paranaguá, baixio não vegetado.Abstract: We tested the hypothesis that the vertical migration of nematode species at a subtropical tidal flat in Paranaguá Bay (S Brazil) is determined by their prevailing feeding and locomotion strategies, conditioned by body morphology. Samples were collected in 4 replicate cores (diameter 2.5 cm), down to a depth of 5 cm (sectioned into 0.5 cm sediment layers) in each of three randomized sites of 1 m2. Variations in vertical distribution of nematode abundance and chlorophyll-a contents were related to exposure changes during a semidiurnal mixed tidal cycle (T1, tidal period just before exposure; T2, two hours after T1, exposed; T3, four h after T1, exposed; T4, six h after T1, at the beginning of flood tide). Despite significant differences in nematode numbers, species responses were rather similar among sites. There was a general trend towards downward migration between T1 and T3, with nematode population sizes increasing with increasing depth in the sediment, probably as a response to high desiccation and temperature. Vertical distribution patterns did not change significantly between T3 and T4, suggesting a response to tidal currents on nematode migration. Feeding strategies were determinant to explain the relative vertical distribution of the predator (2B) Viscosia glabra, known for its active behavior, which migrated downward (p=0,002), probably following preferential prey. The numerically dominant, selective-deposit feeders (1A) Terschellingia longicaudata and Spirinia parasitifera responded differently to exposure. The first was more active and migrated to deeper layers (p=0,016), while the second was less active and showed no vertical movements, remaining in subsurface sediment layers (p=0,496). Our results supported the tested hypothesis that migration patterns heavily depend on feeding modes, but are modulated by locomotion behavior. Keywords: marine nematodes, vertical migration, feeding strategies, locomotion behavior, Paranaguá Bay, intertidal mudflat

Relação entre a variação espacial de metacomunidades meiofaunais e atributos da paisagem

Orientador: Prof. Dr. Gustavo Fernandes Camargo FonsecaTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências da Terra, Centro de Estudos do Mar, Programa de Pós-Graduação em Sistemas Costeiros e Oceânicos. Defesa : Pontal do Paraná, 26/03/2018Inclui referênciasResumo: Ao longo desta tese, investiguei as relações entre nematoides de vida livre e a heterogeneidade da paisagem em sedimentos inconsolidados. Os padrões de variação na estrutura da comunidade foram avaliados em múltiplas escalas espaciais e temporais, usando uma combinação de abordagens experimentais e diversas ferramentas estatísticas, organizadas em quatro capítulos diferentes. Ao fazer isso, tentei inferir alguns dos mecanismos subjacentes à montagem e à dinâmica da metacomunidade de nematoides marinhos, e como a mudança climática pode afetá-los. Os capítulos individuais foram orientados por três pontos principais dentro da ecologia de metacomunidades: 1) a estrutura das metacomunidades em paisagens dinâmicas heterogêneas; 2) o efeito de mudanças de longo prazo na dinâmica da metacomunidade; 3) a importância da variabilidade espaço-temporal em pequena escala para monitorar as metacomunidades. Palavras-chave: Biodiversidade. Nematoda. Ecologia da Paisagem. Macroecologia. Meiofauna. Distribuição Espacial. Dinâmica Temporal. Mudanças Climáticas. Aquecimento. Acidificação.Abstract: Throughout this thesis, I investigated the relationships between free-living nematode fauna and soft-sediment landscape heterogeneity. The variation patterns in community structure across multiple spatial and temporal scales were assessed using a combination of several statistical tools and experimental approaches that are organized into four different chapters. By doing this I tried to infer some of the underlying mechanisms driven metacommunity assembly and dynamics, as well how climate change may affect them, laying light over new analytical perspectives and interpretations in nematode ecology. The individual chapters were oriented by three main issues of metacommunity ecology: 1) the structure of metacommunities in dynamic heterogeneous landscapes; 2) the effect of long-term changes in metacommunity dynamics; 3) the importance of small-scale spatiotemporal variability for monitoring metacommunities. Key-words: Biodiversity. Free-living marine nematodes. Landscape structure. Macroecology. Meiofauna. Spatial distribution. Temporal dynamics. Climate Change. Warming. Acidificatio

Composition and abundance of benthic microalgae from the Estuarine Complex of Paranaguá Bay (southern Brazil) with special emphasis on toxic species

This study addressed the occurrence and distribution of benthic microalgae, with emphasis on toxic species, on differentsubstrates (macroalgae, seagrass and sediments) along the outer, euhaline zone of the Estuarine Complex of ParanaguáBay, southern Brazil, from July 2015 to May 2016. Canonical analysis of principal coordinates (CAP) was used to identifythe potential environmental drivers of microphytobenthic assemblage structure. A total of 18 potentially toxic benthicmicroalgae species were reported, including 7 dinoflagellates, 9 cyanobacteria, one diatom and one euglenophyte.The abundance of all potentially toxic microalgae varied consistently along the investigated period. Dinoflagellatesdominated the microalgae assemblage in July and September 2015. Mean densities on macrophytes ranged from 33.6cells g-1 in May 2016 to 775.6 cells g-1 in September 2015, being positively correlated with dissolved nitrogen-nutrients,water transparency, salinity, and chlorophyll-a. Prorocentrum cf. lima was the most frequent and abundant dinoflagellate.Overall, the highest abundance of toxic species occurred in February 2016, when cyanobacterial mats dominated byLyngbya cf. aestuarii were observed throughout the estuary associated with periods of heavier rainfall and higher turbidity(shallower Secchi depth). At that time, a selected microphytobenthic extract exhibited acute toxicity on nauplii of thebrine shrimp Artemia salina in the laboratory

Chronological brain lesions after SARS-CoV-2 infection in hACE2-transgenic mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes respiratory disease, but it can also affect other organs including the central nervous system. Several animal models have been developed to address different key questions related to Coronavirus Disease 2019 (COVID-19). Wild-type mice are minimally susceptible to certain SARS-CoV-2 lineages (beta and gamma variants), whereas hACE2-transgenic mice succumb to SARS-CoV-2 and develop a fatal neurological disease. In this article, we aimed to chronologically characterize SARS-CoV-2 neuroinvasion and neuropathology. Necropsies were performed at different time points, and the brain and olfactory mucosa were processed for histopathological analysis. SARS-CoV-2 virological assays including immunohistochemistry were performed along with a panel of antibodies to assess neuroinflammation. At 6 to 7 days post inoculation (dpi), brain lesions were characterized by nonsuppurative meningoencephalitis and diffuse astrogliosis and microgliosis. Vasculitis and thrombosis were also present and associated with occasional microhemorrhages and spongiosis. Moreover, there was vacuolar degeneration of virus-infected neurons. At 2 dpi, SARS-CoV-2 immunolabeling was only found in the olfactory mucosa, but at 4 dpi intraneuronal virus immunolabeling had already reached most of the brain areas. Maximal distribution of the virus was observed throughout the brain at 6 to 7 dpi except for the cerebellum, which was mostly spared. Our results suggest an early entry of the virus through the olfactory mucosa and a rapid interneuronal spread of the virus leading to acute encephalitis and neuronal damage in this mouse model.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: The CBIG Consortium (constituted by IRTA-CReSA, BSC, and IrsiCaixa) is supported by Grifols pharmaceutical. The authors also acknowledge the crowdfunding initiative of https://www.yomecorono.com.Peer Reviewed"Article signat per 12 autors/es: Enric Vidal*, Carlos López-Figueroa*, Jordi Rodon, Mónica Pérez, Marco Brustolin, Guillermo Cantero, Víctor Guallar, Nuria Izquierdo-Useros, Jorge Carrillo, Julià Blanco, Bonaventura Clotet, Júlia Vergara-Alert, Joaquim Segalés"Postprint (published version

Benthic Habitat Quality Assessment in Estuarine Intertidal Flats Based on Long-Term Data with Focus on Responses to Eco-Restoration Activity

A long-term assessment of the benthic habitat quality of intertidal flats in Liaohe Estuary was conducted by three integrating ecological indices, AZTI’s Marine Biotic Index (AMBI), Multivariate-AMBI (M-AMBI), and Shannon–Wiener diversity index (H′) based on macrobenthos data from 2013 to 2020. The results showed that the macrobenthic communities were characterized by indifferent and sensitive species of AMBI ecological groups. The annual ranges of H′, AMBI, and M-AMBI were 0.77–1.56, 1.44–3.73 and 0.36–0.54, respectively. Noticeable differences were found among assessment obtained by these biotic indices. Approximately 100%, 24%, and 78% sampling sites had “moderate”, “poor”, and “bad” statuses as assessed by H′, AMBI, and M-AMBI, respectively. Compared with H′ and AMBI, M-AMBI may be more applicable to evaluate the benthic habitat quality of intertidal flats in Liaohe Estuary. Results suggest that the benthic habitat quality in the middle parts of intertidal flats still had an unacceptable status and has not improved radically to date after large-scale “mariculture ponds restored to intertidal flats”.publishedVersio

Identifying "vital attributes" for assessing disturbance-recovery potential of seafloor communities

Despite a long history of disturbance–recovery research, we still lack a generalizable understanding of the attributes that drive community recovery potential in seafloor ecosystems. Marine soft‐sediment ecosystems encompass a range of heterogeneity from simple low‐diversity habitats with limited biogenic structure, to species‐rich systems with complex biogenic habitat structure. These differences in biological heterogeneity are a product of natural conditions and disturbance regimes. To search for unifying attributes, we explore whether a set of simple traits can characterize community disturbance–recovery potential using seafloor patch‐disturbance experiments conducted in two different soft‐sediment landscapes. The two landscapes represent two ends of a spectrum of landscape biotic heterogeneity in order to consider multi‐scale disturbance–recovery processes. We consider traits at different levels of biological organization, from the biological traits of individual species, to the traits of species at the landscape scale associated with their occurrence across the landscape and their ability to be dominant. We show that in a biotically heterogeneous landscape (Kawau Bay, New Zealand), seafloor community recovery is stochastic, there is high species turnover, and the landscape‐scale traits are good predictors of recovery. In contrast, in a biotically homogeneous landscape (Baltic Sea), the options for recovery are constrained, the recovery pathway is thus more deterministic and the scale of recovery traits important for determining recovery switches to the individual species biological traits within the disturbed patch. Our results imply that these simple, yet sophisticated, traits can be effectively used to characterize community recovery potential and highlight the role of landscapes in providing resilience to patch‐scale disturbances.Peer reviewe

Alteration in the Culex pipiens transcriptome reveals diverse mechanisms of the mosquito immune system implicated upon Rift Valley fever phlebovirus exposure

Rift Valley fever phlebovirus (RVFV) causes an emerging zoonotic disease and is mainly transmitted by Culex and Aedes mosquitoes. While Aedes aegypti-dengue virus (DENV) is the most studied model, less is known about the genes involved in infection-responses in other mosquito-arboviruses pairing. The main objective was to investigate the molecular responses of Cx. pipiens to RVFV exposure focusing mainly on genes implicated in innate immune responses. Mosquitoes were fed with blood spiked with RVFV. The fully-engorged females were pooled at 3 different time points: 2 hours post-exposure (hpe), 3- and 14-days post-exposure (dpe). Pools of mosquitoes fed with non-infected blood were also collected for comparisons. Total RNA from each mosquito pool was subjected to RNA-seq analysis and a de novo transcriptome was constructed. A total of 451 differentially expressed genes (DEG) were identified. Most of the transcriptomic alterations were found at an early infection stage after RVFV exposure. Forty-eight DEG related to immune infection-response were characterized. Most of them were related with the RNAi system, Toll and IMD pathways, ubiquitination pathway and apoptosis. Our findings provide for the first time a comprehensive view on Cx. pipiens-RVFV interactions at the molecular level. The early depletion of RNAi pathway genes at the onset of the RVFV infection would allow viral replication in mosquitoes. While genes from the Toll and IMD immune pathways were altered in response to RVFV none of the DEG were related to the JAK/STAT pathway. The fact that most of the DEG involved in the Ubiquitin-proteasome pathway (UPP) or apoptosis were found at an early stage of infection would suggest that apoptosis plays a regulatory role in infected Cx. pipiens midguts. This study provides a number of target genes that could be used to identify new molecular targets for vector control.info:eu-repo/semantics/publishedVersio

Chronological brain lesions after SARS-CoV-2 infection in hACE2-transgenic mice

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes respiratory disease, but it can also affect other organs including the central nervous system. Several animal models have been developed to address different key questions related to Coronavirus Disease 2019 (COVID-19). Wild-type mice are minimally susceptible to certain SARS-CoV-2 lineages (beta and gamma variants), whereas hACE2-transgenic mice succumb to SARS-CoV-2 and develop a fatal neurological disease. In this article, we aimed to chronologically characterize SARS-CoV-2 neuroinvasion and neuropathology. Necropsies were performed at different time points, and the brain and olfactory mucosa were processed for histopathological analysis. SARS-CoV-2 virological assays including immunohistochemistry were performed along with a panel of antibodies to assess neuroinflammation. At 6 to 7 days post inoculation (dpi), brain lesions were characterized by nonsuppurative meningoencephalitis and diffuse astrogliosis and microgliosis. Vasculitis and thrombosis were also present and associated with occasional microhemorrhages and spongiosis. Moreover, there was vacuolar degeneration of virus-infected neurons. At 2 dpi, SARS-CoV-2 immunolabeling was only found in the olfactory mucosa, but at 4 dpi intraneuronal virus immunolabeling had already reached most of the brain areas. Maximal distribution of the virus was observed throughout the brain at 6 to 7 dpi except for the cerebellum, which was mostly spared. Our results suggest an early entry of the virus through the olfactory mucosa and a rapid interneuronal spread of the virus leading to acute encephalitis and neuronal damage in this mouse model