Roberto González-De Zayas

Coastal lagoons are exposed to a variety of stressors, including natural and anthropogenic ones. Due to the rapid degradation of many of these lagoons, environmental and governmental authorities have implemented actions to restore their original or stable state, and hence the ecological functions of these ecosystems. Laguna Larga is a highly impacted and polluted Caribbean coastal lagoon in Cuba. It has low water transparency, high nutrient and eutrophication levels and a low dissolved oxygen concentration. Between 2010 and 2012, restoration actions such as dredging and channel opening were implemented to improve water quality and trophic conditions. Some physicochemical parameters and nutrients were determined between 2010 and 2014 at 12 sites inside the lagoon. To detect significant differences among the parameters assessed, a non-parametric Kruskal-Wallis test was used. Since the samples were not taken at regular time intervals and to handle missing data in our dataset by applying the non-parametric Mann-Kendall test, the missForest machine learning method was used. The concentration of nutrients, oxygen and salinity was similar to that of previous studies and showed an increase in nutrients and in the trophic state from the outer to the inner section of the lagoon. Salinity (0.2 per year) and dissolved oxygen (0.1 mg/L) showed a slight but significant decreasing trend. All the nutrients measured (except dissolved inorganic nitrogen) showed a significant decreasing trend after the restoration actions. Laguna Larga is an impacted tropical lagoon that needs more actions to restore the ecosystem, including the closure of wastewater discharge points and seawater pumping from the adjacent ocean.

La detección temprana de especies de plantas exóticas invasoras es fundamental para la formulación de estrategias de gestión y mitigación. Se propone evaluar la distribución espacio-temporal de Eichhornia crassipes (Mart.) Solms, en laguna La Turbina, empleando imágenes satelitales Sentinel-2 (periodo 2021-2023). Las bandas espectrales de las regiones del visible, borde rojo, infrarrojo cercano e infrarrojo de onda corta, se emplearon como datos de entrada de tres algoritmos de aprendizaje automático durante el proceso de clasificación. Se analizó la relación de la cobertura de la planta con la temperatura del aire y las precipitaciones. El modelo donde se combinan las bandas espectrales y los índices espectrales seleccionados, mediante el método de eliminación recursiva Random Forest, fue el más eficiente en la detección de E. crassipes. Los meses de menor cobertura de E. crassipes fueron diciembre 2022, enero y marzo 2023, debido a las acciones de limpieza mecanizada. E. crassipes se concentró en el Noreste y Suroeste de la laguna, como macrófita emergente. La dirección del viento y la intervención humana, determinaron la distribución espacio-temporal de la planta. Se recomienda realizar confinamientos de E. crassipes, en su condición de macrófita flotante, en las zonas más profundas de La Turbina.

Small-sized invertebrates inhabiting hard substrates in coral reefs (a.k.a. cryptofauna) contribute substantially to reef biodiversity, but their patterns of distribution and ecological controls are poorly understood. Here, we characterized the cryptofauna community and explored “bottom-up” and “top-down” controls by benthic cover and fish abundance, respectively. We sampled the cryptofauna inhabiting the reef terrace from 13 sites along 200 km in Jardines de la Reina (Cuba), a well-preserved and protected area in the Caribbean. We counted 23,959 invertebrates of 14 higher taxa, being the most abundant Copepoda (54%), Nematoda (21%), Mollusca (7%), Ostracoda (5%), Polychaeta (5%), and Amphipoda (3%). Richness, abundance, and community structure varied across the reefs without any geographical gradient of distribution. One-third of the variance occurred at site scale (~ 10 km), and half occurred at quadrat scale (~ 1 m). Algal cover promoted cryptofauna richness and abundance likely providing substrate and food, while live coral cover negatively influenced nematode abundances, potentially due to coral defenses. Relationships between cryptofauna and reef fishes were also present, with invertivores and herbivores negatively affecting cryptofauna abundance likely due to direct or indirect predation pressures. This research highlights the important roles of bottom-up and top-down controls, by algal/coral cover and fishes, respectively, on cryptofauna and in extension to coral reef biodiversity. Current threats by climate change are expected to alter these controls on cryptofauna resulting in changes to diversity, trophodynamics and energy flows of coral reefs.

Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms have promising organic compounds. These species are invasive aquatic plants present in some freshwater lagoons in Cuba. Using its phytochemical properties can be a way out of its negative impact. Water quality from two lagoons was evaluated. The content of phenols, anthraquinones and flavonoids were evaluated for both species. The extraction was made with ethanol (90 %), and the High-Performance Thin-Layer Chromatography analytical technique was used for the phytochemical test. Both lagoons were highly polluted. E. crassipes were observed in two forms: dense and not dense stands. The content of phenolic compounds ranged from 3.07 to 9.2 mg g-1 DW, the anthraquinones ranged from 1.06 to 3.74 mg g-1 DW and flavonoids ranged from 33.9 to 18.2 mg g-1 DW. The highest content of organic compounds was recorded in the dense stands of E. crassipes. Some coincidences for morindin and rubiadin standards were found in P. stratiotes. Coincidences for kaempferol and quercetin standards were also found in the samples. The results of this study suggest that both species of plants could be used as a source of organic compounds by the pharmaceutical industry of Cuba.

The composition of the substrates in the vegetable seedbed phase is important for subsequent transplanting. The aim of this study was to evaluate the use of dry mass of the invasive aquatic plants Pistia stratiotes L. and Eichhornia crassipes (Mart.) Solms as a substrate mixed with Red Ferralitic soil for seedbeds of tomato and pepper. To plant tomato and pepper seeds, 300 alveoli were prepared with a mixture of Red Ferralitic soil with different proportions of dry mass of P. stratiotes (0.5% and 1.0%) and E. crassipes (2.0% and 4.0%). At 28 and 40 d after sowing, 30 seedlings per treatment were selected and the average length and diameter of the stem and primary root (cm) were measured. The Dickson quality index was determined in order to select the best treatment. The average stem length was greater in seedlings treated with P. stratiotes (0.5%) and E. crassipes (2.0%) and the diameter was greater in tomato seedlings treated with P. stratiotes (1.0%) and pepper seedlings with P. stratiotes (0.5%); this showed significant differences from the rest of the treatments. The maximum length and diameter of the primary root varied between treatments for both vegetables. The best treatments for the initial growth of tomato and pepper were those when Red Ferralitic soil and dry mass of P. stratiotes (0.5% and 1.0%) and E. crassipes (2.0%) were used as a mixed substrate.

Irma was a major hurricane that developed during the 2017 season. It was a category 5 on the Saffir–Simpson Hurricane wind scale. This hurricane caused severe damage in the Caribbean area and the Florida Keys. The social, economic, and environmental impacts, mainly related to coastal flooding, were also significant in Cuba. The maximum limits of coastal flooding caused by this hurricane were determined in this research. Field trips and the use of the GPS supported our work, which focused on both the northern and southern coasts of the Ciego de Ávila province. This work has been critical for improving coastal flooding scenarios related to a strong hurricane, as it has been the first experience according to hurricane data since 1851. Results showed that the Punta Alegre and Júcaro towns were the most affected coastal towns. The locals had never seen similar flooding in these places before. The differences between flood areas associated with Hurricane Irma and previous modeled hazard scenarios were evident (the flooded areas associated with Hurricane Irma were smaller than those modeled for categories 1, 3, and 5 hurricanes). The effects of this hurricane on the most vulnerable coastal settlements, including the impacts on the archeological site “Los Buchillones”, were also assessed.

Se estudiaron siete lagunas artificiales de agua dulce (L1 – L7) en el municipo de Ciego de Ávila (Cuba), los cuales se caracterizaron según criterios genéticos, hidrológicos y morfológicos. Todas son lagunas, de origen antrópico, relativamente recientes. Una de ellas es semipermanente (L.1) y las restantes son permanentes. A partir de la identificación de las plantas presentes en parcelas delineadas, desde los bordes de las lagunas, fue confeccionada una lista florística. Los taxones identificados fueron catalogados según su origen y presencia en Cuba, hábito de crecimiento, utilidad para el hombre, comportamiento ante el impacto antrópico y estado de conservación. Se registraron 49 especies pertenecientes a 44 géneros y 34 familias. En L.3 y L.6 (lagunas ubicadas en las Canteras del Aereopuerto) se identificó el mayor número de especies (27 y 26 respectivamente) y en L.1, el menor (7). Predominaron plantas exóticas y sinantrópicas y abundaron las invasoras, lo cual indica el tránsito por etapas tempranas de la sucesión ecológica. No obstante, se detectó un 31 % de plantas autóctonas y un 2 % de endemismo. Un 4 %se encuentran amenazadas de extinción, clasificadas en Peligro Crítico. El 39 % tiene uso medicinal, el 29 % ornamental, el 12 % son fitorremediadoras y el 4 % aparecen frecuentemente incorporadas a prácticas folclóricas. Las plantas asociadas a estas lagunas artificiales del municipio de Ciego de Ávila presentan condiciones, valores y usos diversos, lo que incrementa los servicios ambientales de estos ecosistemas.

Reseña bibliográfica de Carlos Hugo A. Zayas González del libro de Stuart M. McManus, Empire of Eloquence. The Classical Rhetorical Tradition in Colonial Latin America and the Iberian World. Ideas in context. Cambridge: Cambridge University Press. 300 pp. ISBN 978-1-83016-4.

Nitrogen and phosphorous loading drives eutrophication of aquatic systems. Lakes and reservoirs are often effective N and P sinks, but the variability of their biogeochemical dynamics is still poorly documented, particularly in tropical systems. To contribute to the extending of information on tropical reservoirs and to increase the insight on the factors affecting N and P cycling in aquatic ecosystems, we here report on a long-term N and P mass balance (2003–2018) in Valle de Bravo, Mexico, which showed that this tropical eutrophic reservoir lake acts as a net sink of N (−41.7 g N m⁻² y⁻¹) and P (−2.7 g P m⁻² y⁻¹), mainly occurring through net sedimentation, equivalent to 181% and 68% of their respective loading (23.0 g N m⁻² y⁻¹ and 4.2 g P m⁻² y⁻¹). The N mass balance also showed that the Valle de Bravo reservoir has a high net N atmospheric influx (31.6 g N m⁻² y⁻¹), which was 1.3 times the external load and likely dominated by N₂ fixation. P flux was driven mainly by external load, while in the case of N, net fixation also contributed. During a period of high water level fluctuations, the net N atmospheric flux decreased by 50% compared to high level years. Our results outlining water regulation can be used as a useful management tool of water bodies, by decreasing anoxic conditions and net atmospheric fluxes, either through decreasing nitrogen fixation and/or promoting denitrification and other microbial processes that alleviate the N load. These findings also sustain the usefulness of long-term mass balances to assess biogeochemical dynamics and its variability.

This study was conducted in the Jardines de la Reina National Park, Cuba. The health of the communities of corals and crustose coralline algae was studied in the years 2001, 2012 and 2017. The probable effect of hurricanes and sea surface temperature on these communities was also assessed. The area was only affected by three hurricanes and a tropical storm from 2000 to 2017. Sea surface temperature showed an increasing trend (by 0.03°C). The highest percentage of old mortality was recorded in 2001 (74% on the fore reef and 53% on reef crests) and the lowest of recent mortality in 2012 (0.03% on the fore reef and 0.17% on reef crests). Coral cover increased on the fore reef by between 3% and 2% in 2017 in comparison with 2001 and 2012. On the reef crests, the highest cover percentage was in 2001 (14.8%). Unlike local stressors, it was determined that hurricanes and sea surface temperature have likely negatively affected the coral reefs, particularly on reef crests. Both habitats have shown resistance and/or recovery capacity from the impacts suffered after 2001, which suggests some level of resilience.