RESUMEN El 31 de enero de 2020 se concretó la salida del Reino Unido de la Unión Europea, proceso al cual se le denominó Brexit,t, producto de un referéndum donde el 51% de los británicos se pronunció a favor del abandono de la UE, pasando a un estatus denominado Acuerdo de Cooperación y Comercio entre la Unión Europea y el Reino Unido (ACC) que entró en vigor el 1 de mayo de 2021, producto de lo anterior se experimentó inestabilidad en materia política con breves lapsos de gobierno en el caos del primer ministro, por lo cual el objetivo del presente texto radica en el análisis de las condiciones que dieron paso al Brexit y sus implicaciones en el ámbito político y económico. Por lo tanto, en términos metodológicos este artículo, se realizado una revisión documental mediante el abordaje de fuentes secundarias. Se concluye, como era de esperar, que los efectos en materia económica y social no se hicieron esperar, para el caso la variación interanual del PIB en el tercer trimestre de 2022, fue del 1,9%, así mismo un aumento del desempleo de un 3.6%. Por otra parte, es preciso considerar que la política inglesa aun cuando experimenta una notable volatilidad, como producto de ello se han emprendiendo acciones para afrontar los efectos posteriores al Brexit.

ABSTRACT On January 31, 2020, the United Kingdom's exit from the European Union took place, a process known as Brexit,t as a result of a referendum in which 51% of the British people voted in favor of leaving the EU, moving to a status known as Cooperation and Trade Agreement between the European Union and the United Kingdom (CTA), which came into force on May 1, 2021, as a result of the above, instability was experienced in political matters with brief lapses of government in the chaos of the Prime Minister, so the objective of this text lies in the analysis of the conditions that gave way to Brexit and its implications in the political and economic sphere. Therefore, in methodological terms this article, a documentary review was conducted by approaching secondary sources. It is concluded, as expected, that the effects in economic and social matters were not long in coming, for the case the interannual variation of GDP in the third quarter of 2022, was 1.9%, likewise an increase in unemployment of 3.6%. On the other hand, it is necessary to consider that English politics, even when experiencing a notable volatility, as a result of this, actions have been taken to face the post-Brexit effects.

Abstract Picoplankton are central global carbon (C) cycling players and often dominate the ocean plankton communities, especially in low latitudes. Therefore, evaluating picoplankton temporal dynamics is critical to understanding microbial stocks and C fluxes in tropical oceans. However, the lack of studies on low-latitude picoplankton communities translates into a common conception that there is an absence of seasonality. Herein, we studied the temporal variation in abundance (measured by flow cytometry), and carbon flux (taking bacterial production and respiration as proxies) of the picoplanktonic community for the first time, as well as their environmental drivers in a low-latitude (05° 59’ 20.7″S 035° 05’ 14.6″W) Atlantic coastal station. We performed monthly samplings between February 2013 and August 2016 in a novel microbial observatory – hereafter called the Equatorial Atlantic Microbial Observatory – established on the northeastern Brazilian Atlantic coast. Our results revealed stability in temporal dynamics of picoplankton, despite a considerable inter-annual variation, with some related to the El Niño (ENSO) event in 2015. However, weak environmental relationships found were not enough to explain the variation in picoplankton’s abundance, which suggests that other factors such as biological interactions may lead to picoplankton abundance variation over time. Heterotrophic bacteria dominated picoplankton during the entire study period and between photosynthetic counterparts, and Synechococcus showed greater relative importance than picoeukaryotes. These results bring a novel perspective that picoplankton may exhibit more pronounced fluctuations in the tropical region when considering inter-annual intervals, and is increasing prokaryotic contribution to carbon cycling towards the equator. (C latitudes Therefore oceans However lowlatitude latitude seasonality Herein measured cytometry, cytometry , cytometry) taking proxies time 05° 05 (05 59 207S S 20 7 035 14.6″W 146W W 14 6 station 201 coast interannual inter annual ENSO (ENSO 2015 picoplanktons s counterparts picoeukaryotes intervals equator 0 (0 5 2 03 1 (

Abstract A long-term fern demography study that included measurements of plant traits of three species in the dimorphic genus Danaea (1991-2009) was conducted in a rainforest in Puerto Rico beginning two years after the first major hurricane (Hugo) since the early 1930s. Both vegetative (sterile) leaves and spore-bearing (fertile) leaves on tagged plants were monitored repeatedly to document not only differences between two types of leaves, but also patterns of annual variation during a timespan that included the passage in 1998 of hurricane Georges. While all three species had fertile leaf lifespans of six mo or less, Danaea geniculata and D. polymorpha had much longer mean sterile leaf spans (54.4 mo, 52.7 mo) than D. nodosa (33.5 mo). All three species had significant year-to-year trait differences, often with immediate increases after Hurricane Georges levels returning to or below pre-hurricane levels in subsequent years. Long-term observations of annual variation in traits of herbaceous layer ferns that mainly follows the passage of a major hurricane highlight the importance of this study as the frequency and magnitude of hurricanes due to climate change are predicted to increase, although more experimental studies to identify specific causes of these long-term trends are needed. longterm long term 19912009 1991 2009 (1991-2009 Hugo (Hugo 1930s s (sterile sporebearing spore bearing (fertile 199 less D 54.4 544 54 4 (54. 527 52 7 52. 33.5 335 33 5 (33. mo. . yeartoyear year prehurricane pre Longterm Long increase needed 1991200 200 (1991-200 19 54. (54 33. 3 (33 199120 20 (1991-20 1 (5 (3 19912 2 (1991-2 ( (1991- (1991 (199 (19 (1

Resumen Un estudio demográfico a largo plazo de helechos que incluyó mediciones de rasgos de plantas de tres especies del género dimórfico Danaea (1991-2009) se realizó en un bosque lluvioso en Puerto Rico, comenzando dos año después del primer huracán (Hugo) de gran impacto desde principios de los 1930. Se monitorearon repetidamente tanto las hojas vegetativas (estériles) como las hojas productoras de esporas (fértiles) en plantas determinadas, para documentar no solo las diferencias entre los dos tipos de hojas, sino también los patrones de variación anual durante un período de tiempo que incluyó el paso en 1998 del huracán Georges. Aunque las tres especies tenían una vida útil de hojas fértiles de seis meses o menos, Danaea geniculata y D. polymorpha tenían hojas estériles con una media de vida mucho más larga (54,4 meses, 52,7 meses) que D. nodosa (33,5 meses). Las tres especies mostraron diferencias significativas en sus rasgos característicos de un año a otro, a menudo con aumentos inmediatos después del paso del huracán Georges, volviendo a niveles similares o inferiores a los previos al paso del huracán en años posteriores. Las observaciones a largo plazo de la variación anual en los rasgos de helechos de la capa herbácea, tras el paso de un huracán de mayor impacto, resaltan la importancia de este tipo de estudio, ya que se predice un aumento en la frecuencia y la magnitud de los huracanes debido al cambio climático. Se necesitan más estudios experimentales para identificar causas específicas de estas tendencias a largo plazo. 19912009 1991 2009 (1991-2009 Rico Hugo (Hugo 1930 (estériles (fértiles determinadas 199 Georges menos D 54,4 544 54 4 (54, 527 52 7 52, 33,5 335 33 5 (33, meses. . otro posteriores herbácea climático 1991200 200 (1991-200 193 19 54, (54 33, 3 (33 199120 20 (1991-20 1 (5 (3 19912 2 (1991-2 ( (1991- (1991 (199 (19 (1

ABSTRACT The presence of juvenile Branchiostoma elongatum captured in plankton samples from the north-central coast of Chile during February-March of consecutive years (2013-2020) is described. Its low abundance showed interannual variation as well as its frequency of occurrence. Its geographical distribution was preferably coastal. It covered the entire sampling area (1-20 nm from the coast) longitudinally, and specimens were captured between the extreme north of the sampling area and 30°20’S. The lowest abundances were found in years of negative thermal anomalies (2017-2018) and the highest mainly in neutral conditions (2013-2015).

ABSTRACT The control of the fishing effort and establishment of individual catch quotas has been proposed as a strategy to manage the Pacific hake (Merluccius productus) fishery in the north of the Gulf of California. In this study, the issues related to the efficiency of hake fishing vessels are analyzed. Two different types of vessels, large and small, were identified using the physical characteristics of 53 vessels in a cluster analysis. Using generalized linear models (GLM), efficiency variation (catch per unit of effort CPUE) was assessed with data derived from onboard observations of 74 trips made by 25 vessels and 814 sets from 2015 to 2019. The variables used to determine their contribution to CPUE were years, vessel types, fishing areas, depth strata, and their interactions. The factors year, fishing area, net type, and vessel type explain the interannual variability in the CPUE. The model, which included the interactions, showed 18% of explained deviance and indicated that interactions between year and area and between depth and vessel were significant and contributed the most to the deviance explained by the model. A GLM exhibited 11% of the explained deviance without considering interactions and indicates that large vessels are 1.5 times more efficient than small vessels.

RESUMO A presença de grandes quantidades de macrófitas aquáticas em reservatórios pode desencadear diversos impactos no ecossistema local e o uso de metodologias convencionais para seu monitoramento retorna apenas informações do momento presente. Com isso em vista, este estudo teve como objetivo mapear a variação espaço-temporal da cobertura de macrófitas utilizando imagens Landsat 5, 7 e 8 para o período de 1984-2021 no reservatório Jupiá, Brasil, além de determinar curvas e mapas de permanência da cobertura de macrófitas. A identificação desses organismos nas imagens, e sua distinção de outras espécies vegetais, foi feita através de índices espectrais (NDVI, GNDVI e GSAVI) e da determinação do intervalo característico de cada uma dessas classes, a qual se deu por distribuições de probabilidade. Foram observadas variações interanuais na disposição espacial das macrófitas e tendência de crescimento da área, sendo este último possivelmente causado pela implantação de um reservatório a montante. Apesar da quantidade de imagens sem interferências ter sido uma limitação, a construção de uma série histórica de ocupação de macrófitas e a determinação de curvas e mapas de permanência mostraram-se satisfatórias e poderão auxiliar na tomada de decisões de manejo desses organismos.

ABSTRACT The presence of large amounts of aquatic macrophytes in reservoirs can trigger several impacts on the local ecosystem and conventional methodologies used for their monitoring only returns information from the present moment. With that in mind, this study aimed to map spatio-temporal variation of macrophyte cover using Landsat 5, 7 and 8 images between 1984-2021 at Jupiá reservoir, in south east of Brazil, besides determining curves and maps of macrophyte cover permanence. The identification of these organisms in the images, and their distinction from other vegetations, was made through spectral indices (NDVI, GNDVI and GSAVI) and the determination of the characteristic range of each of these classes, which was given by probability distributions. Interannual variations were observed in the spatial arrangement of macrophytes and the area's growth trend, possibly being caused by the implantation of an upstream reservoir. Although the number of images without interference was a limitation, the construction of a historical series of macrophytes occupation and the determination of permanence curves and maps proved to be satisfactory and could help on the decision-making processes for the management of these organisms.

ABSTRACT The larvae of Blepharipoda spinosa and Lepidopa chilensis were collected from Chile's north-central coast (Paposo 25.0°S and Oscuro Port 31.5°S) in each February of 2013-2017. Larvae were separated by their development stage. Their abundance, occurrence, and distribution concerning its proximity to the coast were analyzed. Larval abundance and frequency of occurrence were low in both species. Zoea I dominated the highest concentrations detected in coastal stations and near the study area's longest sandy beaches. Interannual variation of larvae was seen in the abundance and composition by development stages. The highest abundance of B. spinosa larvae was found in February 2016, while L. chilensis larvae had the highest abundance in February 2014. Their presence and development stages in the wide sampling area provide information on both species’ distribution and reproductive activity.

Abstract The influence of environmental variables on planktonic biodiversity is widely known. However, the absence of information about the cyanobacterial community in tropical estuarine regions motivated this work, whose objective was to investigate the spatio-temporal variation of cyanobacterial density related to physicochemical factors in a Brazilian Amazonian estuary. For the qualitative and quantitative study of cyanobacteria and physicochemical variables, samples were collected in April/July/2009 and April/August/2010. We identified 31 species of the orders Chroococcales, Oscillatoriales and Nostocales. Species of the genera Aphanocapsa, Dolichospermum, Komvophoron, Microcystis, Pseudanabaena and Merismopedia were frequent and abundant throughout the study period. Some of the found genera have already been described as potential toxin producers. The dynamics of cyanobacteria were temporal, the highest densities occurred in 2010 (average= 1080.86 ± 702.86 cells.mL-1) mainly influenced by the high values of pH, temperature, electrical conductivity, total dissolved solids, ammonium nitrogen which led cyanobacteria to present different responses in terms of richness, density and diversity between the years.

ABSTRACT Stream insects use in different ways the stream habitats which affect patterns of species occurrence on stream. The nestedness is one of these patterns being an ecological mechanism that generates beta diversity. In this study, we verify the effects of temporal environmental variations on nestedness patterns of Chironomidae assemblages on subtropical streams. We collected chironomid larvae during winter and summer during three years (2010, 2011 and 2012) in Brazilian Subtropical low-order streams (Erechim, state of Rio Grande do Sul, Brazil). We measured environmental variables in each stream. To assess if assemblages will show nested patterns intra- and interannual we used a NODF metric. We observed nestedness only in one year, this pattern was due to variation of limnological factors, which are directly associated with climatic conditions (precipitation and water temperature) and agricultural management (e.g. dissolved oxygen and nutrients). Climatological events affect Chironomidae community through the time. The variations on precipitation values could be one of the mainly factors that influence nestedness for this community. Finally, studies on nesting on time scales should consider inter-annual comparisons, as climatic variations are more evident.

Resumen Introducción: La variación anual de las características de los anillos de crecimiento tiene repercusiones en la productividad y calidad de la madera. Objetivo: Evaluar el crecimiento radial en dos plantaciones de Pinus patula Schltdl. & Cham. de diferente edad e intensidad de aclareo, y su relación con la variación interanual de temperatura y precipitación. Materiales y métodos: Las características de los anillos de crecimiento se analizaron en muestras de madera de plantaciones de 13 y 23 años, sometidas a tres intensidades de aclareo (nulo, ligero y moderado). Las características se relacionaron con los datos climáticos de los años de formación de los anillos mediante análisis de correlación de Pearson. Resultados y discusión: En la plantación 1995, las características de los anillos no mostraron diferencias significativas (P > 0.10) entre las parcelas con y sin aclareo, debido al exceso de competencia y recesión de la copa. La anchura de anillo, de madera temprana y tardía se asociaron significativamente (P < 0.10; r ≥ 0.40) con la temperatura mínima promedio. En la plantación 2005, los árboles de las parcelas con aclareo mostraron anchura de anillos, anchura de madera temprana e incremento en área basal mayores que los de la parcela sin aclareo. En esta plantación solo la anchura de madera tardía se asoció positivamente con la temperatura (P < 0.10; r = 0.69) y negativamente con la precipitación anual (P < 0.10; r = -0.61). Conclusión: El espacio de crecimiento y la intensidad de competencia afectaron principalmente la anchura de anillo y de madera temprana. Los factores ambientales influyen en las características de los anillos.

Abstract Introduction: Annual variation in growth ring characteristics has an impact on productivity and wood quality. Objective: To evaluate radial growth in two Pinus patula Schltdl. & Cham. plantations of different ages and thinning intensity, as well as its relationship to interannual variation in temperature and rainfall. Materials and methods: Growth ring characteristics were analyzed in wood samples from 13- and 23-year-old plantations, subjected to three thinning intensities (null, light and moderate). The characteristics were related to climate data during the years of ring formation using Pearson's correlation analysis. Results and discussion: In the 1995 plantation, ring characteristics did not show significant differences (P > 0.10) between plots with and without thinning, due to excessive competition and crown recession. Ring width, and early and latewood width, was significantly associated (P < 0.10; r ≥ 0.40) with average minimum temperature. In the 2005 plantation, trees from the thinned plots showed greater ring width, earlywood width and basal area increment than those from the unthinned plot. In this plantation only latewood width was positively associated (P < 0.10; r = 0.69) with temperature and negatively (P < 0.10; r = -0.61) with annual rainfall. Conclusion: Growing space and competition intensity mainly affected ring and earlywood width. Environmental factors influence ring characteristics.

The presence of the Giant African Snail (Achatina fulica) as an exotic species in Colombia since 2008 has promoted social alerts, control actions and research efforts on different aspects of natural history under the environmental conditions of the national territory. With the purpose of consolidating the knowledge that has been generated and disseminated on the Giant African Snail in Colombia during the 10 years of presence, information was sought in the main scientific and public databases at national and international level. This information was filtered according to the source, the year, the area and the subject, analyzing the temporal variation of the presence and control reports. This information comes from the media, establishing 2014 and 2016 as the years of greatest disclosure and predominant management and control issues, followed by presence records. According to the chronology of the consolidated information, the hypothesis of the entry of mollusk into the country is supported. A relationship was found between the frequency of presence records with interannual (e.g., ENSO) and intra-annual climatic processes (e.g., seasonal variation associated with the temporal dynamics of the intertropical convergence zone). In addition, it was found that although community-mediated control strategies have been given a higher priority, scientific knowledge on the adjustment of the biological and ecological characteristics of the species to the environmental conditions of the country has not been generated.

La presencia del caracol gigante africano (Achatina fulica) como especie exótica en Colombia desde 2008 ha impulsado alertas sociales, acciones de control y esfuerzos de investigación sobre diferentes aspectos de la historia natural bajo las condiciones ambientales del territorio nacional. Con el propósito de consolidar el conocimiento generado y divulgado acerca del caracol gigante africano en Colombia durante los 10 años de presencia, se buscó información en las principales bases de datos científicas y públicas a nivel nacional e internacional. Esta información se filtró según la fuente, el año, la zona y el tema, y se analizó la variación temporal de los reportes de presencia y control. La mayor parte de la información disponible proviene de los medios de comunicación. Se establecieron los años 2014 y 2016 como los de mayor divulgación, predominando temas de manejo y control, seguidos por los registros de presencia. De acuerdo con la cronología de la información consolidada se soporta la hipótesis de la entrada del molusco al país. Se encontró una relación entre la frecuencia de los registros de presencia con procesos climáticos de escala interanual (e.g., ENOS) e intra-anual (e.g., variación estacional asociado a la dinámica temporal de la zona de convergencia intertropical). Además, se detectó que aunque se le dio una prioridad mayor a las estrategias de control mediado por la comunidad, no se generó aún suficiente conocimiento científico sobre las características biológicas y ecológicas de la especie, en relación con las condiciones ambientales del país.

Background and aims: Pollen grains represent one of the main biological pollutants in the air causing allergies in the population. To know the biological quality of the air and how it varies throughout the year, is essential to implement therapeutic and preventive measures. It was proposed: 1) to determine the allergenic potential of the atmospheric pollen spectrum of the city of Mar del Plata, 2) to elaborate a pollen calendar with the most allergenic taxa, and 3) to establish pollen stations that allow to identify the periods with greater incidence of pollen, recognizing the main allergenic contributors. M&M: Aerobiological monitoring was carried out for one year with a volumetric and continuous aerobiological sampler. Results: The average daily concentrations totaled 12742 grains. Fifty pollen types were recorded; 30 were allergenic (21 arboreal and 9 herbaceous). The taxa with a moderate or high allergenicity were: Cupressaceae, Poaceae, Cedrus and Platanus with more than 5% per year, and Acer, Urticaceae, Moraceae, Myrtaceae, Populus, Ulmus and Fraxinus with values between 2 and 5%. Also Ambrosia and Artemisia that are highly allergenic, all were included in a pollen calendar to visualize the duration, intensity and seasonality of each individual pollination period. Five main pollen stations were defined by the abundase of taxa with high levels of allergenicity: February-March, April, August, September-October, November-December. Conclusions: Ninety-five percent of airborne pollen grains along the year are allergenic or potentially allergenic. Aerobiological monitoring continues to incorporate interannual variations.

Introducción y objetivos: Los granos de polen representan uno de los principales contaminantes biológicos del aire ya que causan alergias en gran parte de la población. Conocer la calidad biológica del aire y cómo varía a lo largo del año, es fundamental para implementar medidas terapéuticas y preventivas. En este trabajo, se planteó: 1) determinar la potencialidad alergénica del espectro polínico atmosférico de la ciudad de Mar del Plata, 2) elaborar un calendario polínico con los taxones más alergénicos, y 3) establecer estaciones polínicas que permitan identificar los periodos con mayor incidencia de polen alergénico, reconociendo los principales contribuyentes. M&M: Se realizó un monitoreo aerobiológico durante un año con una muestreador aerobiológico, volumétrico y continuo. Resultados: Las concentraciones medias diarias sumaron 12742 granos. Se registraron 50 tipos polínicos, 30 de los cuales fueron alergénicos (21 arbóreos y 9 herbáceos). Los taxones con una alergenicidad moderada o alta fueron: Cupressaceae, Poaceae, Cedrus y Platanus con más del 5% anual, y Acer, Urticaceae, Moraceae, Myrtaceae, Populus, Ulmus y Fraxinus con valores entre 2 y 5%. Con ellos, más Ambrosia y Artemisia que son altamente alergénicos, se estableció un calendario polínico que permitió visualizar la duración, intensidad y estacionalidad de cada período de polinación individual. Además, se determinaron cinco estaciones polínicas definidas por taxones abundantes y con niveles altos de alergenicidad: febrero-marzo, abril, agosto, setiembre-octubre, noviembre-diciembre. Conclusiones: El 95% del polen anual es alergénico o potencialmente alergénico. Se continúa con el monitoreo aerobiológico para incorporar las variaciones interanuales.

RESUMO Os otólitos são estruturas espécie-específicas de peixes cuja análise morfológica é uma ferramenta eficiente para identificação e discriminação de estoques e/ou populações sujeitas a variações clinais. O presente trabalho buscou elucidar o grau de variação morfológica dos otólitos sagitta do dourado, Coryphaena hippurus Linnaeus, 1758 capturado ao largo da costa sudeste do Brasil pela frota pesqueira sediada no Rio de Janeiro. Os 164 pares de otólitos analisados foram obtidos a partir de amostras coletadas entre fevereiro de 2014 e outubro de 2016. A forma e o contorno dos otólitos sagitta foram caracterizados através de seis descritores (área, perímetro, circularidade, retangularidade, excentricidade e dimensão fractal) e análises de Fourier elíptica (AFE), a partir de imagens dos otólitos. Comparações interanuais dos descritores de formas apontaram diferenças significativas (PERMANOVA p<0,0001), com exceção da retangularidade e dimensão fractal. A análise discriminante linear (ADL) entre anos, apresentou melhor classificação (94,8%) para o ano de 2015, cuja disponibilidade de dados foi mais consistente. A análise de agrupamento das 30 harmônicas, baseada no algoritmo hierárquico de Ward, revelou quatro morfotipos de otólitos. A análise de componentes principais (ACP) das harmônicas dos 82 otólitos examinados não discriminou as áreas de captura. Assim, os morfotipos observados denotam a existência de um polimorfismo em toda área de estudo, determinado provavelmente por um balanço de seleção, i.e., seleção por equilíbrio temporal. Tal suposição foi corroborada através de estudos genéticos realizados nesta região, cuja hipótese da presença de dois morfotipos capturáveis/comercializáveis (dourado vs. palombeta) na área foi rejeitada, confirmando a presença de um estoque misto.

ABSTRACT The otoliths are structures species-specific of fishes whose morphologic analysis is an efficient tool for identification and discrimination of stocks and/or populations subjected to clinal variations. This work intends to show the degrees of morphologic variation in sagitta otoliths of dolphinfish, Coryphaena hippurus Linnaeus, 1758, landed by the fishing fleet from Rio de Janeiro. The 164 pairs of otoliths analyzed were obtained from biological samples collected between February 2014 and October 2016. The shape and the contour of sagitta otoliths were characterized by means of six descriptors (area, perimeter, circularity, rectangularity, eccentricity and fractal dimension) and Elliptical Fourier Analysis (EFA), from the images of otoliths. Interannual comparisons of shape descriptors showed significant differences (PERMANOVA p<0.0001) except rectangularity and fractal dimension. The linear discriminant analysis (LDA) between years exhibited a better classification (94.8%) for 2015, when the data was more consistent. The cluster analysis of the 30 harmonics based on Ward’s hierarchical algorithm revealed four otolith morphotypes. The principal components analysis (PCA) from harmonics of the 82 otoliths examined did not show spatial discrimination between fishing areas. Therefore, the observed morphotypes corroborate the existence of a polymorphism in the study area, determined by balanced temporal selection. This supposition can be supported by genetic studies realized in the region, where the hypothesis of two commercial morphotypes was rejected, confirming the presence of a mixed stock.

RESUMO A seca de 2020 no Sul do Brasil, que culminou no final do verão e início do outono (fevereiro-março-abril), apresentou um dos mais deficientes totais pluviométricos em tal trimestre. Tal período do ano já vinha apresentando predominância de desvios pluviométricos negativos desde o final dos anos 1990. Esta recente seca representa, portanto, piora significativa num quadro já desfavorável de disponibilidade hídrica. Tal comportamento de longo prazo deve-se à combinação de fases opostas de duas oscilações climáticas interdecadais na temperatura da superfície do mar: a fase positiva da Oscilação Multidecadal do Atlântico e a fase negativa da Oscilação Interdecadal do Pacífico. Tal combinação produz variação no estado básico da atmosfera que favorece estiagem no Sul do Brasil nessa época do ano e a ocorrência mais frequente de secas. Para que ocorra um evento extremo, geralmente é necessário que, em adição a oscilações interdecadais, ocorra um evento de oscilação interanual que também favoreça a seca, como os eventos de El Niño Central em 2020 e La Niña em 2009 e 2012, anos de secas no Sul do Brasil durante a mesma combinação de fases das duas oscilações interdecadais. Mudanças climáticas antrópicas podem intensificar a frequência e intensidade destes eventos extremos.

ABSTRACT The 2020 drought in southern Brazil, which culminated in late summer and early autumn (February-March-April), displayed one of the most deficient rainfall totals in such trimester. This period of the year has already been dominated by negative rainfall deviations since the end of the 1990s. This recent drought represents, therefore, a significant worsening in an already unfavorable situation of water availability. Such long-term behavior is due to the combination of opposite phases of two interdecadal oscillations in the sea surface temperature: the positive phase of the Atlantic Multidecadal Oscillation and the negative phase of the Pacific Interdecadal Oscillation. This combination produces variation in the atmospheric basic state that favors less rainfall in southern Brazil at this time of the year and more frequent occurrence of droughts. For an extreme event to occur, it is usually necessary that, in addition to interdecadal oscillations, an interannual oscillation event occurs that also favors drought, such as the events of Central El Niño in 2020 and La Niña in 2009 and 2012, years of droughts in southern Brazil during the same phase combination of the two interdecadal oscillations. Anthropic climate changes can intensify the frequency and intensity of these extreme events.

Abstract: The Gulf of Batabanó (GB), is the region of the Cuban marine platform of greater extension and fishing importance. Habitat effects of marine species have been reported as a consequence of natural and anthropic factors. The objective was to determine significant spatio-temporal variations in the hydrology of GB in different periods and environmental situations. For this, the variability of rainfall and air temperature was analyzed in 1975-1995 and 1996-2015 periods of low and high cyclonic activity, the thermohaline characteristics of the GB before (1959-1970) and after (2006-2016) the river damming, and the effect of two hurricanes almost simultaneous in 2008 ("Gustav" and "Ike"). Significant differences in the interannual variability of meteorological parameters between the north and south of the GB corresponded to local characteristics, and changes occurred in the distribution of the months of maximum rainfall. The perennial impact of the damming, coupled with temporary precipitation deficits in spring, summer and winter, caused thermohaline increases in 2006-2016, with an increase of 0.7 °C in water temperature and 2.3 in average salinity of the GB, with respect to 1959-1970. Salinity showed an increase in the distribution of hypersaline values, and an average > 36 in months of high rainfall, with a general average of 35.4 in 1959 -1970 and 37.7 in 2006-2016, this suggests that damming has been a major factor in the increase in salinity. The thermohaline impact in the GB of two hurricanes in 2008 was restored in the short term, with greater inertia in turbidity.

Resumen: El golfo de Batabanó (GB), es la región de la plataforma marina cubana de mayor extensión e importancia pesquera. Afectaciones al hábitat de especies marinas han sido señaladas como consecuencia de factores naturales y antrópicos. El objetivo fue determinar variaciones espacio-temporales significativas en la hidrología del GB en diferentes periodos y situaciones ambientales. Para ello se analizó la variabilidad de la lluvia y la temperatura del aire en 1975-1995 y 1996-2015 periodos de baja y alta actividad ciclónica, las características termohalinas del GB anterior (1959-1970) y posterior (2006-2016) al represamiento fluvial, y el efecto de dos huracanes casi simultaneaos en 2008 (“Gustav” e “Ike”). Diferencias significativas en la variabilidad interanual de parámetros meteorológicos entre el norte y el sur del GB respondieron a características locales, y ocurrieron cambios en la distribución de los meses de máximas precipitaciones. El represamiento fluvial, sumado a déficits de precipitación en primavera, verano e invierno, provocaron aumentos termohalinos en 2006-2016, con incremento de 0,7 °C en la temperatura del agua y de 2,3 en la salinidad promedio del GB, respecto a 1959-1970. La salinidad mostró una ampliación en la distribución de valores hipersalinos, y media > 36 en meses de altas precipitaciones, con promedio general de 35,4 en 1959-1970 y 37,7 en 2006-2016, esto sugiere que el represamiento ha sido un factor principal en las variaciones de salinidad. El impacto termohalino en el GB de dos huracanes en 2008, se restableció en corto plazo, con mayor inercia en la turbidez.