RESUMO O uso de águas com alta concentração de sais no cultivo do cajueiro se faz necessário na região semiárida do Nordeste brasileiro, devido à escassez hídrica e à má distribuição das chuvas. O excesso de sais na água é um fator limitante para a produção agrícola. Nesse cenário, estratégias têm sido empregadas para mitigar os efeitos nocivos do estresse salino sobre as plantas, destacando-se o uso do ácido salicílico. Com isso, o objetivo deste trabalho foi avaliar os efeitos da aplicação foliar de ácido salicílico sobre os aspectos fisiológicos e crescimento do cajueiro anão precoce cultivado sob estresse salino na fase de pré-floração. O experimento foi conduzido em casa de vegetação utilizando o delineamento em blocos casualizados, em arranjo fatorial 5 × 4, com cinco níveis de condutividade elétrica da água de irrigação (CEa - 0,4; 1,2; 2,0; 2,8 e 3,6 dS m-1) e quatro concentrações de ácido salicílico - AS (0, 1, 2 e 3 mM), com três repetições. O ácido salicílico, aplicado na concentração de 1 mM, atenuou os efeitos do estresse salino na morfofisiologia do cajueiro durante a fase de pré-floração, especialmente em plantas irrigadas com CEa de até 1,2 dS m-1. Por outro lado, a concentração de 3 mM AS elevou os efeitos negativos do estresse salino no teor relativo de água, extravasamento de eletrólitos, pigmentos fotossintéticos, trocas gasosas e crescimento de cajueiro anão precoce, particularmente em CEa de 3,6 dS m-1.

ABSTRACT The use of water with high concentration of salts in cashew cultivation is a necessity in the semi-arid region of Northeast Brazil, due to water scarcity and poor rainfall distribution. Excess salts in water are a limiting factor for agricultural production. In this scenario, strategies have been employed to mitigate the harmful effects of salt stress on plants, and the use of salicylic acid stands out. With this, the aim of this study was to evaluate the effects of foliar application of salicylic acid on the physiology and growth of early dwarf cashew grown under salt stress in the pre-flowering stage. The experiment was conducted in a greenhouse using a randomized block design, in a 5 × 4 factorial arrangement, with five levels of electrical conductivity of irrigation water (ECw - 0.4, 1.2, 2.0, 2.8, and 3.6 dS m-1) and four concentrations of salicylic acid (SA - 0, 1, 2, and 3 mM), with three replicates. Salicylic acid, applied at a concentration of 1 mM, mitigated the negative impacts of salt stress on the morphophysiology of cashew during the pre-flowering phase, especially in plants irrigated with ECw of up to 1.2 dS m-1. On the other hand, the concentration of 3 mM SA exacerbated the effects of salt stress on the relative water content, electrolyte leakage, photosynthetic pigments, gas exchange, and growth of early dwarf cashew, particularly at ECw of 3.6 dS m-1.

ABSTRACT Spermidine (Spd), a naturally occurring molecule in plants, is being investigated for its potential to improve the bean’s tolerance to salinity stress. This study explores how common beans (Phaseolus vulgaris L.) can be helped to thrive in salty environments. This research involved a group receiving regular watering with half strength Hoagland’s solution (HS), and other group watered with a modified form of the same solution containing 75 mM NaCl to stimulate salt stress. Seedlings were treated with foliar applications of Spd (0, 0.5, 1 mM) at five intervals: 15, 20, 25, 30, and 35 d after sowing. Applying Spd significantly reduced damage caused by salt and protected essential pigments for photosynthesis (total chlorophyll by 33% and carotenoids by 57% over than the Spd-untreated plants under saline conditions). Additionally, 1 mM Spd enhanced the antioxidant enzyme activities, i.e., superoxide dismutase, catalase, and ascorbate peroxidase by 15%, 55% and 4.6% and promoted the buildup of beneficial compounds like proline, free amino acids and sugars. Remarkably, exogenous Spd application reduced Na+ accumulation while improving K+ content in common beans under salinity stress. Additionally, it enhanced the cell membrane stability index (CMSI) during stressful situations, the maximum CMSI (94.31%) was recorded with 1 mM Spd under non-stress conditions, whereas the minimum CMSI (72.97%) was registered under salinity without Spd. Under salinity condition, the real-time quantitative PCR (qRT-PCR) results demonstrated a significant increase in the expression of the vacuolar-localized Na+/H+ antiporter protein (NHX1), and the multifunctional osmotic protection protein (Osmotin) in comparison to the control. Furthermore, common bean treated with Spd showed significantly higher expression levels of SOS1, NHX1, and Osmotin, under normal and salinity conditions, with the highest gene expression observed under 1 mM spermidine treatment under saline conditions. Spermidine at 1 mM notably decreased malondialdehyde levels compared to 0.5 mM (10.68 vs. 12.11 nmol g-¹ FW). Overall, the findings propose that Spd may be an effective tool for cultivating common beans in saline areas, potentially paving the way for increased food production in challenging environments.

Groundwater is an essential part of food and water security. This critical resource must be managed appropriately and used sustainably. This study aimed to assess groundwater quality, suitability for domestic and irrigation purposes, and factors contributing to the groundwater chemistry, in the Breede Water Management Area (WMA), Western Cape, South Africa. Groundwater samples were collected and analysed for major ions such as K+, Mg²+, Na+, Ca²+, Cl-, HCO3-, NO3-, F-, SO4(2-) and physical variables like pH, electrical conductivity (EC), total dissolved solids (TDS), and temperature. Water quality index (WQI), total hardness (TH), South African Water Quality Guidelines (SAWQG) and World Health Organisation (WHO) drinking water quality guidelines were used to assess suitability for drinking purposes. Permeability index (PI), magnesium hardness (MH), sodium adsorption ratio (SAR), sodium percentage (Na%) and graphical representations such as Wilcox and United States Salinity Laboratory (USSL) diagram were used to assess suitability for irrigation purposes. Multivariate statistical analysis and the Piper diagram were used to determine the geochemical processes influencing the groundwater quality. TH and WQI revealed that, overall, groundwater in Breede WMA is soft and suitable for drinking. The irrigation suitability indices showed that groundwater is suitable for irrigation, with the exception of a few sites that are doubtful. The dominating water type in the area is Na-Cl, followed by mixed Ca-Mg-Cl. Multivariate statistical methods revealed that the groundwater is affected by the dissolution of rock salts, calcite dissolution, cation exchange and agricultural activities. The overall groundwater in the Breede Water Management Area is suitable for domestic purposes. Water in the boreholes along the coastal area and Borehole W1 must be treated before domestic and irrigation use. There must be consistent groundwater quality monitoring in Breede to identify changes in groundwater quality.

ABSTRACT Due to the important functions of calcium in plant physiology, supplementation of this nutrient may be a viable strategy to increase the tolerance of plants to salinity. Thus, the objective in this study was to evaluate the gas exchange and growth of broad-leaf arugula cultivars cultivated in coconut fiber subjected to salt stress. Four nutrient solutions [(S1 - standard nutrient solution (electrical conductivity of water - ECw of 0.5 dS m-1; S2 - nutrient solution using saline water with NaCl at 3.5 dS m-1; S3 - S2 enriched with Ca(NO3)2 at 50%; S4 - S2 enriched with Ca(NO3)2 at 100%, obtaining values of 2.3, 5.1, 5.5, and 5.9 dS m-1, for S1, S2, S3, and S4, respectively], and two cultivars of arugula (Donatella and Gigante Folha Larga), arranged in a 2 × 4 factorial scheme, with three replicates, were studied. Plants were harvested 40 days after sowing and evaluated for the following variables: plant height, number of leaves, leaf area, total fresh mass, total dry mass, specific leaf area, leaf succulence, relative chlorophyll index, stomatal conductance, CO2 assimilation rate, transpiration rate, internal CO2 concentration, instantaneous water use efficiency, and intrinsic carboxylation efficiency. The cultivar Gigante Folha Larga was more tolerant to salinity of nutrient solution. The use of salinized nutrient solution negatively affected arugula growth and physiology, but the extra addition of Ca(NO3)2 reduced the harmful effects of salinity. Extra addition of 50% of Ca(NO3)2 in the nutrient solution is recommended to reduce the effect of salt stress. physiology Thus broadleaf broad stress S1 S [(S electrical 05 0 5 0. m1 m 1 m-1 35 3 3. CaNO32 CaNO Ca NO3 NO Ca(NO3) 50 100 100% 23 2.3 51 5.1 55 5.5 59 9 5. m1, 1, respectively, respectively , respectively] Donatella Larga, Larga) scheme replicates studied variables height leaves area mass succulence index conductance CO rate concentration efficiency m- CaNO3 Ca(NO3 10 2. Ca(NO

RESUMO Devido às importantes funções do cálcio na fisiologia vegetal, a suplementação deste nutriente pode ser uma estratégia viável para aumentar a tolerância das plantas à salinidade. Assim, o objetivo deste estudo foi avaliar as trocas gasosas e o crescimento de cultivares de rúcula de folhas largas cultivadas em fibra de coco submetidas ao estresse salino. Quatro soluções nutritivas [(S1-solução nutritiva padrão (condutividade elétrica da água - CEa de 0,5 dS m-1; S2- solução nutritiva utilizando água salina com NaCl a 3,5 dS m-1; S3-S2 enriquecida com Ca(NO3)2 a 50%; S4-S2 enriquecido com Ca(NO3)2 a 100%, obtendo valores de 2,3, 5,1, 5,5 e 5,9 dS m-1, para S1, S2, S3 e S4, respectivamente], e duas cultivares de rúcula. (Donatella e Gigante Folha Larga), dispostas em esquema fatorial 2 × 4, com três repetições, foram estudadas. As plantas foram colhidas 40 dias após a semeadura e avaliadas quanto às seguintes variáveis: altura de planta, número de folhas, área foliar, massa fresca total, massa seca total, área foliar específica, suculência foliar, índice relativo de clorofila, condutância estomática, taxa de assimilação de CO2, taxa de transpiração, concentração interna de CO2 e eficiência instantânea do uso da água e eficiência intrínseca de carboxilação. A cultivar Gigante Folha Larga foi mais tolerante à salinidade da solução nutritiva. O uso de solução nutritiva salinizada afetou negativamente o crescimento e a fisiologia da rúcula, mas a adição extra de Ca(NO3)2 reduziu os efeitos nocivos da salinidade. Recomenda-se adição extra de 50% de Ca(NO3)2 na solução nutritiva para reduzir o efeito do estresse salino. vegetal Assim salino S1solução Ssolução S1 S condutividade 05 0 5 0, m1 m 1 m-1 S2 35 3 3, S3S2 SS S3-S CaNO32 CaNO Ca NO3 NO Ca(NO3) 50 S4S2 S4 S4-S 100 100% 23 2,3 51 5,1 55 5, 59 9 m1, 1, respectivamente, respectivamente , respectivamente] Donatella Larga, Larga) 4 repetições estudadas variáveis planta total específica clorofila estomática CO transpiração carboxilação Recomendase Recomenda se m- S3S CaNO3 Ca(NO3 S4S 10 2, Ca(NO

ABSTRACT The development of aquaculture through the cultivation of what are considered unconventional species is an option with the potential to solve the problem of food scarcity. The aim of the present study was to evaluate the zootechnical performance of juvenile Pomacea haustrum fed different commercial diets, and subjected to different levels of salinity. After seven P. haustrum spawn had hatched in the laboratory, the juveniles were randomly selected and transferred to the rearing containers. Two different commercial diets were offered: rabbit feed with a high proportion of ingredients rich in crude vegetable protein (VP), and dog food containing balanced levels of ingredients rich in crude vegetable and animal protein (MP). The selected juveniles were randomly stocked at different salinities (0, 2 and 4 parts per thousand - ppt). The experiment lasted 65 days. Twenty-one hours after the start of the experiment, 100% of the individuals reared at a salinity of 4 ppt had died. There was a significant difference (p ≤ 0.05) between the results for zootechnical performance (average final weight, weight gain, average final growth, specific growth rate, protein efficiency and apparent feed conversion) for animals reared in fresh water or at a salinity of 2 ppt, regardless of the type of diet. The origin of the protein in the diet had no significant effect on the zootechnical performance of the individuals; however, the salinity of the water impaired development of the animals in direct proportion to its concentration. scarcity P laboratory containers offered VP, VP , (VP) MP. MP . (MP) 0, 0 (0 ppt. ppt) 6 days Twentyone Twenty one 100 died p 0.05 005 05 gain rate conversion however concentration (VP (MP ( 10 0.0 00 1 0.

RESUMO O feijão-caupi (Vigna unguiculata (L.) Walp.) é um dos principais grãos que fazem parte do consumo alimentar dos brasileiros, no entanto, sua produção é afetada pelas características edafoclimáticas e pela alta salinidade da água de irrigação. Objetivou-se com a pesquisa avaliar os efeitos das concentrações de quitosana na fisiologia e produção de feijão-caupi sob estresse salino. O experimento foi realizado em casa de vegetação em Campina Grande, PB, utilizando-se o delineamento inteiramente casualizado, em esquema fatorial 2 × 5, sendo dois níveis de condutividade elétrica da água de irrigação (CEa - 0,6 e 4,0 dS m-1) e cinco concentrações de quitosana (0; 0,25; 0,50; 0,75 e 1,00 g L-1) com quatro repetições cada uma consistindo de três plantas. A irrigação com água de condutividade elétrica de 4,0 dS m-1 afetou negativamente a síntese de pigmentos fotossintéticos, a fluorescência da clorofila a e a produção de grãos de feijão-caupi cultivar BRS Tapaihum. A aplicação foliar de quitosana entre as concentrações de 0,46 e 0,71 g L-1 amenizou os efeitos do estresse salino, aumentando a eficiência fotoquímica, a produção e o índice de grãos por planta. As aplicações de quitosana sob água de irrigação com condutividade elétrica de 0,6 dS m-1 promoveram aumento no comprimento médio da vagem, produção de grãos e índice de grãos das plantas de feijão-caupi cv. BRS Tapaihum. feijãocaupi feijão caupi Vigna L. L (L. Walp. Walp brasileiros entanto Objetivouse Objetivou se salino Grande PB utilizandose utilizando casualizado 5 CEa 06 0 6 0, 40 4 4, m1 m 1 (0 0,25 025 25 0,50 050 50 075 75 0,7 100 00 1,0 L1 m- fotossintéticos Tapaihum 046 46 0,4 071 71 L- fotoquímica planta vagem cv (L ( 0,2 02 0,5 05 07 7 10 1, 04

ABSTRACT Cowpea (Vigna unguiculata (L.) Walp.) is one of the main grain crops that form part of Brazilian food consumption, but its production is affected by edaphoclimatic conditions and high salinity of the irrigation water. The aim of this research was to evaluate the effects of chitosan concentrations on the physiology and production components of cowpea grown under salt stress. The experiment was conducted in a greenhouse, adopting a completely randomized design, in a 2 × 5 factorial scheme, with two levels of electrical conductivity of irrigation water (ECw - 0.6 and 4.0 dS m-1) and five concentrations of chitosan (0, 0.25, 0.50, 0.75, and 1.00 g L-1), with four replicates, each of which consisting of three plants. Irrigation water with electrical conductivity of 4.0 dS m-1 negatively affected the synthesis of photosynthetic pigments, chlorophyll a fluorescence, and grain production of cowpea cv. BRS Tapaihum. Foliar application of chitosan at concentrations between 0.46 and 0.71 g L-1 mitigated the deleterious effects of salt stress on photochemical efficiency, grain production, and grain index per plant. Chitosan applications under irrigation water of electrical conductivity of 0.6 dS m-1 promoted an increase in the mean pod length, grain production and grain index of cowpea plants cv. BRS Tapaihum. Vigna L. L (L. Walp. Walp consumption greenhouse design scheme ECw 06 0 6 0. 40 4 4. m1 m 1 0, (0 025 25 0.25 050 50 0.50 075 75 0.75 100 00 1.0 L1, L1 , L-1) replicates m- pigments fluorescence cv Tapaihum 046 46 0.4 071 71 0.7 L- efficiency plant length (L ( 02 0.2 05 0.5 07 7 10 1. 04

RESUMO A salinidade é um fator abiótico que prejudica o crescimento e os mecanismos fisiológicos, bioquímicos e moleculares das plantas. Entre as plantas, a soja é uma cultura importante mundialmente, portanto, o manejo de fatores abióticos é essencial para mitigar os danos às plantas. No entanto, bioestimulantes, como a melatonina, estão sendo usados para aliviar o estresse causado por esses fatores. Portanto, este estudo teve como objetivo avaliar o crescimento, os pigmentos fotossintéticos e as relações hídricas de plantas de soja aplicadas a níveis de salinidade e aplicação exógena de melatonina. A pesquisa foi realizada em área experimental pertencente à Universidade Federal Rural do SemiÁrido, Mossoró, RN, Brasil. O delineamento experimental foi em blocos casualizados, arranjados em esquema fatorial 3 x 3 (três níveis de salinidade na água de irrigação - 0.50, 3.00 e 5.00 dS m-1 e três concentrações de melatonina - 0, 0.5 e 1 mM), com três repetições. Aos 47 dias após o plantio, foram avaliados a altura da planta, diâmetro do caule, número de folhas, comprimento radicular, teor de clorofila (a, b e total), conteúdo relativo de água, umidade foliar e extravasamento de eletrólitos. As plantas de soja toleraram os efeitos da salinidade nos aspectos de crescimento, nos pigmentos fotossintéticos e nas relações hídricas até 3,00 dS m-1, independentemente da concentração de melatonina. A aplicação exógena de melatonina mitigou os efeitos do estresse salino na clorofila b e no conteúdo relativo de água, no nível de salinidade de 5.00 dS m-1 e concentração de 1 mM. fisiológicos mundialmente portanto entanto bioestimulantes Portanto SemiÁrido Mossoró RN Brasil casualizados 050 0 50 0.50 300 00 3.0 500 5 5.0 m1 m m- 05 0. mM, mM , mM) repetições 4 plantio planta caule folhas radicular a, (a total, total total) eletrólitos 3,0 m1, 1, 30 3. 5. 3,

ABSTRACT Salinity is an abiotic factor that impairs the growth and physiological, biochemical, and molecular mechanisms of plants. Among plants, soybeans are an important crop worldwide, so managing abiotic factors is essential to mitigate plant damage. However, biostimulants, such as melatonin, are being employed to alleviate the stress caused by these factors. Therefore, this study aimed to evaluate the growth, photosynthetic pigments, and water relations of soybean plants subjected to salinity levels and exogenous melatonin application. The research was conducted in experimental area belonging to the Federal Rural University of the Semi-Arid Region, Mossoró, RN, Brazil. The experimental design was randomized blocks, arranged in a 3 x 3 factorial scheme (three salinity levels in the irrigation water - 0.50, 3.00, and 5.00 dS m-1 and three melatonin concentrations - 0, 0.5, and 1 mM) with three replications. At 47 days after planting, plant height, stem diameter, number of leaves, root length, chlorophyll content (a, b, and total), relative water content, leaf moisture, and electrolyte leakage were evaluated. Soybean plants tolerated the effects of salinity on growth aspects, photosynthetic pigments, and water relations up to 3.00 dS m-1, regardless of melatonin concentration. Exogenous application of melatonin mitigated the effects of salt stress on chlorophyll b and relative water content at salinity level of 5.00 dS m-1 and concentration of 1 mM. physiological biochemical worldwide damage However biostimulants Therefore pigments SemiArid Semi Arid Region Mossoró RN Brazil blocks 050 0 50 0.50 300 00 500 5 5.0 m1 m m- 05 0.5 mM replications 4 planting height diameter leaves length a, (a total, total , total) moisture evaluated aspects 3.0 m1, 1, 30 5. 0. 3.

Resumen Introducción: Coryphaena hippurus es una especie migratoria de interés comercial, que se encuentra en ambientes tropicales y subtropicales, prefiriendo zonas con un rango de temperatura entre 21 y 30 °C y salinidad cercana a 31 ppt. Aunque la tendencia poblacional del dorado es estable, la pesquería de este recurso está aumentando y ocupa importantes posiciones en la economía de países costeros del Pacífico Oriental Tropical, evidenciándose la necesidad de diseñar y fortalecer estrategias de conservación y mejorar el aprovechamiento de este recurso. Dada su ubicación en ambientes tropicales y subtropicales, la disponibilidad y distribución de este recurso podría verse afectado a futuro por el cambio climático. Objetivo: Analizar la distribución potencial actual y futura de C. hippurus bajo condiciones de cambio climático. Métodos: Se emplearon 10 algoritmos para modelar la distribución potencial e idoneidad de hábitat actual para C. hippurus a partir de la temperatura superficial del mar, la salinidad y velocidad de las corrientes, posteriormente se proyectaron estos resultados según el escenario de cambio climático más extremo. Resultados: Hubo buenos desempeños con todos los algoritmos empleados, pero se escogió el modelo generado con BIOCLIM (AUC: 0.89) pues además resuelve el inconveniente del sesgo espacial y temporal hallado en los registros de la especie. La región de mayor idoneidad de hábitat para C. hippurus coincide con los frentes oceánicos del Pacífico Oriental Tropical. En condiciones futuras de cambio climático extremo, el modelo de distribución de la especie indica una contracción, reubicación y expansión de hábitat hacia el sur de la línea ecuatorial. Conclusiones: En condiciones de cambio climático extremo, el modelo de distribución para C. hippurus sugiere un proceso de tropicalización de los ecosistemas marinos en el Pacífico Oriental Tropical para el año 2100.

Abstract Introduction: Coryphaena hippurus is a species of commercial interest with a high migratory capacity, a characteristic that places it in tropical and subtropical environments, preferring areas with a temperature range between 21 and 30 °C and salinity close to 31 ppt. Although the population trend of C. hippurus is stable, the fishing of this resource is increasing and occupies important positions in the economy of the Eastern Tropical Pacific coastal countries, which demonstrates the need to design and strengthen conservation strategies for the adequate use of this resource. Given its location in tropical and subtropical environments, its availability and distribution could be affected by climate change. Objective: To analyze the current and future potential distribution of C. hippurus under climate change scenarios. Methods: Ten algorithms were used to model the potential distribution and current habitat suitability index of C. hippurus as a function of sea surface temperature, current salinity and velocity, and these results were then projected under the most extreme climate change scenario. Results: There were good performances with all the algorithms used, but the model generated with BIOCLIM (AUC: 0.89) was chosen because it also solves the problem of spatial and temporal bias found in the records of the species. The region of greatest habitat suitability for C. hippurus matches the oceanic fronts of the Eastern Tropical Pacific. Under future conditions of extreme climate change, the species distribution pattern indicates a contraction, relocation, and expansion of habitat south of the equator. Conclusions: Under conditions of extreme climate change, the distribution model for C. hippurus suggests a process of topicalization of marine ecosystems in the Eastern Tropical Pacific by 2100.

Resumen Introducción: Las arqueas metanogénicas (MA) participan en la mineralización anaerobia de la materia orgánica en sedimentos de manglar, su actividad está relacionada con el calentamiento atmosférico por la producción de metano; diversas variables ambientales pueden influir en la dinámica metanogénica y la producción de metano en estos sedimentos. Objetivo: Analizar, mediante técnicas dependientes de cultivo, la abundancia de las arqueas metanógenas viables (AMV) y la producción de metano en diferentes épocas climáticas en los sedimentos del manglar El Morro-La Mancha, Veracruz, Golfo de México. Métodos: De mayo a noviembre 2019, siguiendo un transecto de salinidad, se recolectaron sedimentos del manglar del Morro-La Mancha, en tres localidades, abarcando tres diferentes épocas climáticas, secas (mayo), lluvias (octubre) y nortes (noviembre) (N = 9), cuantificándose la abundancia de las AMV mediante la técnica del Número Más Probable (NMP) con acetato y metanol como substratos; la influencia de los sulfatos en la producción de metano a partir de acetato en microcosmos, se analizó por cromatografía de gases y se evaluaron las variables químicas de salinidad, pH, Eh, carbohidratos, contenido orgánico y carbonatos en los sedimentos. Resultados: Se determinó una abundancia de AMV de 102 a 108 NMP/g de sedimento húmedo, superior a la reportada en otros estudios, dicha abundancia se incrementó cuando se utilizó metanol (104-108 NMP/g sedimento) como sustrato, en comparación con el acetato (102-105 NMP/g sedimento); la producción de metano en los microcosmos aumentó en condiciones libres de sulfatos (29.78-929.75 nmol CH4/mes) y en los sedimentos de la temporada de lluvias. Conclusión: Se destaca la influencia de las condiciones químicas de los sedimentos del manglar sobre la dinámica metanógena, determinándose que, en la temporada de lluvias, una disminución de la salinidad, Eh más electronegativos y el incremento de las fracciones orgánicas favorecieron la metanogénesis.

Abstract Introduction: Methanogenic archaea (MA), participate in the anaerobic mineralization of organic matter in mangrove sediments, their activity is related to atmospheric warming due to the production of methane; several environmental variables can influence the presence of MA and methane production in these sediments. Objective: To analyze, through culture-dependent techniques, viable methanogenic archaea (VMA) in the sediments, and the production of methane from acetate in different climatic periods in the mangrove El Morro-La Mancha, Veracruz, Gulf of Mexico. Methods: From May to November 2019, following a salinity transect, sediment samples from El Morro-La Mancha mangrove were collected at three locations, in three different climatic seasons, dry (May), rainy (October) and northern (November) (N = 9). VMA in the sediments was quantified using the Most Probable Number (MPN) technique with acetate and methanol as substrates. The influence of sulfate on methane production was analyzed from acetate in microcosm by gas chromatography and the chemical variables of salinity, pH, Eh, carbohydrates, organic content, and carbonates in the sediments were evaluated. Results: The abundance of VMA was 102 to 108 MPN/g of wet sediment, higher than that reported in other studies, this abundance was higher when methanol (104-108 MPN/g sediment) was used as substrate, compared to acetate (102-105 MPN/g sediment); methane production in the microcosms increased in sulfate-free conditions (29.78-929.75 nmol CH4/month) and in the sediments of the rainy season. Conclusion: The influence of the chemical conditions of the mangrove sediments on the methanogenic dynamics is highlighted, determining that in the rainy season, the decrease in salinity, more electronegative Eh, and the increase in organic fractions favored the methanogenesis.

Resumen Introducción: Las lagunas salobres son ecosistemas de alta diversidad y con posibilidades para uso humano. Por lo que es necesario mejorar el conocimiento del fitoplancton para entender su impacto real. Objetivo: Relacionar el fitoplancton de la Laguna Mandinga con las condiciones limnológicas durante épocas de secas y lluvias. Métodos: El material se recolectó en tres estaciones: Isla Conchas (ICO), Mandinga Chica (MCH) e Isla del Amor (IA) en secas (marzo 2018) y lluvias (septiembre 2017 y 2018). El análisis limnológico incluyó diez variables abióticas, además del fitoplancton mediante el método de Utermöhl. Los datos fueron analizados por el índice de Shannon (H') y Correspondencia Canónica (ACC). Resultados: Análisis de 136 especies; 68.4 % Heterokontophyta, 22.8 % Dinoflagellata, 5.9 % Cyanobacteria; con 40 eurihalinas y 96 estenohalinas. Las especies más abundantes fueron: Bacillaria paxillifera, Chaetoceros compressus, Coscinodiscus rothii y Chaetoceros atlanticus. La mayor abundancia se registró en ICO (secas) y la menor en MCH (lluvias) con 307 x 103 y 76 x 103 cell/ml, respectivamente. El H' osciló entre 1.31 y 0.70 bits/ind. El CCA mostró una relación entre salinidad y oxígeno disuelto con C. rothii y Ceratoneis closterium. Los fosfatos se asociaron con B. paxillifera, C. atlanticus y Podosira stelligera. Los nitratos, temperatura y pH se correlacionaron con Tripos hircus, T. furca, Diploneis bombus y Merismopedia elegans. Mientras, Skeletonema costatum, Cocconeis scutelum y Nitzschia bicapitata no presentaron correlación con las variables limnológicas. Conclusiones: La Laguna Mandinga es un ecosistema somero, eurihalino y bien oxigenado. La dominancia de diatomeas y dinoflagelados se evidenció por su capacidad para sobrevivir en diferentes concentraciones de salinidad y temperatura. Sugerimos monitorear al fitoplancton por la presencia de Microcystis wesenbergii, B. quinquecornis, Pseudo-nitzschia cf. pungens y P. cf. pseudodelicatissima ya que pueden formar proliferaciones dañinas.

Abstract Introduction: The brackish lagoons are ecosystems with great diversity and possibilities for human use. Therefore, the knowledge about phytoplankton needs to be improved to understand its real impact. Objective: To relate the Mandinga’s Lagoon phytoplankton to the limnological conditions during the dry and wet seasons. Methods: The material was collected in three stations: Isla Conchas (ICO), Mandinga Chica (MCH) and Isla del Amor (IA) during the dry (March 2018) and wet (September 2017 and 2018) seasons. The limnological analysis included ten abiotic variables, and the phytoplankton was analyzed by the Utermöhl method. Data was analyzed with the Shannon index (H') and Canonical Correspondence Analysis (CCA). Results: 136 species were identified: 68.4 % Heterokontophyta, 22.8 % Dinoflagellata, and 5.9 % Cyanobacteria; with 40 euryhaline and 96 stenohaline. The most abundant species were: Bacillaria paxillifera, Chaetoceros compressus, Coscinodiscus rothii, and Chaetoceros atlanticus. The highest abundance was in ICO (dry) and the lowest in MCH (wet), with 307 x 103 and 76 x 103 cells/ml, respectively; the H' ranged from 1.31 to 0.70 bits/ind. The CCA showed a relationship between salinity and dissolved oxygen with C. rothii and Ceratoneis closterium. The phosphates were associated with B. paxillifera, C. atlanticus, and Podosira stelligera. The nitrate, water temperature and pH were related to Tripos hircus, T. furca, Diploneis bombus, and Merismopedia elegans. In contrast, Skeletonema costatum, Cocconeis scutelum, and Nitzschia bicapitata did not correlate with the limnological variables. Conclusions: The Mandinga’s Lagoon is a shallow, euryhaline and well-oxygenated ecosystem. The dominance of diatoms and dinoflagellates was evidenced by their ability to survive in different salinities and temperatures. It is recommended monitor phytoplankton, in particular Microcystis wesenbergii, B. quinquecornis, Pseudo-nitzschia cf. pungens, and P. cf. pseudodelicatissima as they are harmful algae.

Resumen Introducción: Las bahías bioluminiscentes en Puerto Rico desempeñan un papel socioeconómico importante y disminuciones del dinoflagelado bioluminiscente dominante Pyrodinium bahamense son preocupantes. Los estudios muestran proliferaciones erráticas débilmente correlacionadas con factores ambientales locales. Objetivos: Cuantificar cambios en la densidad de dinoflagelados a largo plazo en la Laguna Grande de Fajardo (LGF), comprender cómo el ambiente marino modula esos cambios y determinar los impactos de eventos climáticos extremos en la densidad de dinoflagelados. Métodos: Se recolectaron muestras bimestrales del 2016-2021 en tres sitios de la LGF. La densidad se estimó mediante el conteo de células de Sedgewick Rafter. Condiciones ambientales se obtuvieron de la estación Río Fajardo 5007100 y de la boya NOAA 41056. El clima marino y los indicadores bióticos se obtuvieron por mediciones de teledetección. Se utilizaron correlaciones Kruskal Wallis, Spearman y las correlaciones cruzadas en los registros de campo corto y proxy largos para evaluar los controles ambientales en las proliferaciones de dinoflagelados LGF. Resultados: En seis años de monitoreo se encontraron densidades bajas entre el 2016-2017 y proliferaciones frecuentes e intensas en 2018-2021 marcadas por huracanes. Se registraron valores bajos a finales del invierno, en contraste con valores más altos a finales del verano (agosto-noviembre). Vientos ligeros y la respuesta de capas mixtas al calentamiento estacional en forma de mareas altas y baja salinidad, mantienen la reproducción de los dinoflagelados. Conclusiones: Los dinoflagelados bioluminiscentes son vitales para el turismo costero y requieren manejo de los recursos. En general: 1) los recuentos de dinoflagelados fluctúan ampliamente, 2) los dinoflagelados fluorescentes son sensibles a las condiciones ambientales debido a su estacionalidad limitada y estrecho rango fisiológico, 3) los huracanes juegan un rol de rastrillar y refrescar la laguna costera para su posterior reproducción, y 4) fluctuaciones intra-estacionales se relacionan con las condiciones termodinámicas aire-mar, el balance de salinidad y el nivel del mar.

Abstract Introduction: Bio bays in Puerto Rico play an important socio-economic role and declines in dominant bioluminescent dinoflagellate Pyrodinium bahamense are concerning. Studies show erratic blooms with is weak correlation to in situ environmental factors. Our study examines shorter field and longer proxy records on dinoflagellate density at Laguna Grande de Fajardo (LGF). Objectives: To quantify temporal changes in dinoflagellate density in a long-term monitoring study, understand how the marine environment modulates those changes, and determine the wider impacts of a fluctuating climate and extreme events on proxies for dinoflagellate density. Methods: Bimonthly samples were collected from 2016 to 2021 at three sampling sites in LGF. Dinoflagellates density was estimated by Sedgewick Rafter counting cells. Environmental conditions were obtained from Rio Fajardo 5007100 station and NOAA buoy 41056. Marine climate and biotic proxies were obtained from remote sensing measurements. Kruskal Wallis, Spearman correlations and cross-correlations in the shorter field and longer proxy records were used to evaluate environmental controls on LGF dinoflagellate blooms. Results: Six years of field monitoring densities found a low period in 2016-2017, frequent and intense blooms in 2018-2021 punctuated by hurricanes. Generally low values were recorded in late winter in contrast with higher values in late summer (Aug-Nov). Light winds and mixed layer response to seasonal warming in the form of high tides and low salinity, were found to sustain dinoflagellate reproduction. Conclusions: Bioluminescent dinoflagellates are vital to coastal tourism and require resource management. LGF results show that: 1) dinoflagellate counts fluctuate widely, 2) fluorescing dinoflagellates are sensitive to environmental conditions because of limited seasonality and narrow physiological range, 3) hurricanes play a role by ‘raking and refreshing’ the coastal lagoon for subsequent biotic reproduction, and 4) intra-seasonal fluctuations of density and proxies relate to air-sea thermodynamic conditions, the salinity budget and sea level.

Resumen Antecedentes: Los manglares son comunidades cuya estructura expresa patrones de acuerdo a las geoformas costeras en las que se desarrollan. Preguntas: ¿Existe una variación estructural de los manglares entre geoformas y regiones del Pacífico sur? ¿Cuál es el efecto del factor geomórfico-regional sobre la estructura de los manglares? ¿Cuál es el nivel de consistencia de la estructura de los manglares entre cada geoforma y región analizada? Descripción de datos: Área basal, altura, densidad, índice de complejidad y valor de importancia. Sitio de estudio: Manglares de 39 sistemas de cinco regiones hidrológicas en los estados de Guerrero, Oaxaca y Chiapas, México. Métodos: La clasificación estructural de los manglares se realizó considerando la geoforma (bocana, estero, estuario, laguna) y la región hidrológica. Se emplearon correlaciones para evaluar su relación con la salinidad y la recarga hídrica; y técnicas multivariadas para identificar diferencias entre los factores y patrones de agrupación. Resultados: La densidad y el área basal se correlacionaron positivamente con la recarga hídrica, y se encontró que la densidad y la complejidad del manglar variaron significativamente entre geoformas y regiones; mientras que el área basal y la altura fueron afectadas por geoforma y región. Los grupos discretos de las variables en las ordenaciones no resultó evidente, encontrándose mayor variabilidad estructural de los manglares por región hidrológica que por geoforma. Conclusiones: Existe variación estructural en los manglares entre geoformas y regiones del Pacífico sur, sin embargo, la variación del área basal, altura y densidad es baja, resultando consistente al compararse entre regiones hidrológicas.

Abstract Background: Mangroves are communities whose structure expresses patterns according to the coastal landforms in which they develop. Questions: Is there a structural variation of mangroves among landforms and regions of the South Pacific? What is the effect of the geomorphological-regional factor on the structure of mangroves? What is the level of consistency of mangrove structure within each analyzed landform and region? Data description: Basal area, height, density, complexity index, and importance value. Study site: Mangroves from 39 systems in five hydrological regions in the states of Guerrero, Oaxaca, and Chiapas, Mexico. Methods: The structural classification of mangroves was carried out considering the landform (inlet, estuary, lagoon) and the hydrological region. Correlations were used to assess their relationship with salinity and water recharge, and multivariate techniques were employed to identify differences between factors and clustering patterns. Results: Density and basal area correlated positively with water recharge, and it was found that mangrove density and complexity varied significantly among landforms and regions, while basal area and height were affected by landform and region. Discrete groups of variables in ordinations were not evident, with greater structural variability of mangroves found by hydrological region rather than landform. Conclusions: There is structural variation in mangroves among landforms and regions of the South Pacific; however, the variation in basal area, height, and density is low, resulting in consistency when compared across hydrological regions.

ABSTRACT Salinity stress immensely inhibits rice (Oryza sativa L.) growth, development, and productivity. Hence, two rice introgression lines, Morkho60-2 and BC4F4 132-12-61, were previously developed from ‘RD6’ rice via marker-assisted backcrossing and their adaptive salt-tolerant mechanisms were characterized in this study. Their seedling physiological and transcriptional responses to salinity stress were observed in comparison to the parental ‘RD6’ and ‘Pokkali’. The salt stress responses were assessed under 150 mM NaCl treatment for 9 d. Interestingly, like ‘Pokkali’, salinity did not affect the growth parameters of the new rice genotypes. ‘Pokkali’, Morkho60-2, and BC4F4 132-12-61 also showed lower shoot Na+ content (0.91-1.05 vs. 2.83 mg g-1 DW), and higher selective transport of K+ over Na+ (i.e., ST value of 6.57-10.98 vs. 2.65) than RD6 genotype under salinity stress. Accordingly, the partial least squares-discriminant analysis of all physiological parameters suggested shoot Na+ accumulation and ST value as the key discriminating parameters between ‘RD6’ and the new genotypes. Transcriptional responses of Na+ homeostasis-related genes further supported the findings. In comparison to the salt susceptible ‘RD6’ rice, Na+ vacuolar compartmentalization was suggested in Morkho60-2 roots due to the higher abundance of OsNHX1 (i.e., relative expression of 2.65 vs. 1.59) and OsNHX2 (2.42 vs. 1.29) transcripts. Morkho60-2 also displayed a significant upregulation of root OsSOS1 (2.02 vs. 1.18), which may contribute to root Na+ exclusion. Therefore, we suggest that selective transport of K+ over Na+ and Na+ exclusion enhanced ion homeostasis in the newly improved rice genotypes, allowing the seedlings to adapt to the saline condition.

ABSTRACT. The shape of the shell and the development of bivalve mollusks are strongly associated with the action of environmental conditions. The environmental variables, functional parameters of the shell, and the relative growth of Mytella strigata were seasonally (summer 2020 to spring 2021) determined in three locations: Altata Bay (AB), Macapule Lagoon (ML) and El Colorado Bay (CB) from the southeast Gulf of California (Mexico). Shell dimensions (SL: shell length, SH: shell height, and SW: shell width) showed significant differences. ML mussels obtained the highest measurements (SL = 19.12 ± 1.60 mm, SH = 47.67 ± 3.92 mm, SW = 14.92 ± 1.04 mm, and body weight = 7.54 ± 1.40 g). The greatest shell elongation (SH/SL) was observed in ML (2.49 ± 0.13), while CB recorded the highest compactness and convexity values. SH/SL was the most substantial interaction (R2 = 0.67, 0.63, and 0.55 in AB, ML and CB, respectively). The principal component analysis shows three groupings of the biometric indicators and the relative growth of mussels concerning the environmental parameters in each lagoon. The environmental conditions affected the shape of the shell and relative growth of M. strigata in the three lagoons, emphasizing the type of habitat and salinity as the determining factors. The shell phenotypic plasticity of this mussel represents an adaptive strategy of resilience to the environmental factors in each place.

ABSTRACT. Coastal lagoons are sites recognized for their high biomass and primary productivity levels and are critical habitats for environmental changes. This study evaluated the phytoplankton biomass in the Términos Lagoon (TL), a Ramsar-listed site in the southern Gulf of Mexico, during the 2022 La Niña and 2023 El Niño events. Four systematic sampling expeditions were carried out in April and October of 2022 and 2023 to acquire high-resolution hydrographic data and collect water samples for spectrophotometric determinations of chlorophyll-a (Chl-a) as an indicator of phytoplankton biomass in 11 sites distributed along the TL, while values of the Multivariate ENSO Index (MEI) were used to identify the phase during each sampling expedition. The results showed variations, both seasonally and interannually. MEI values reflected a strong La Niña event during 2022, while in 2023, the ENSO phase moved from neutral (April) to El Niño conditions (October). Consequently, in 2023, the maximum values of the surface temperature and salinity increased by 2.9°C and 9.2, respectively, compared to 2022. Besides, the maximum values of Chl-a decreased to 0.55 mg m-3 between 2022 and 2023. The horizontal distribution of these parameters displayed interesting gradients along the study area related to each event. Our results demonstrate the impact of La Niña and El Niño events on the hydrographic conditions and phytoplankton biomass of a region recognized for its high species richness contribute to understanding physical-biological coupling processes. This aspect remains poorly understood in the region.