Long-term and seasonal changes in production and respiration were surveyed in the Valle de Bravo reservoir, Mexico, in a period during which high water-level fluctuations occurred (2006–2015). We assessed the community metabolism through oxygen dynamics in this monomictic water-body affected by strong diurnal winds. The multiple-year data series allowed relationships with some environmental drivers to be identified, revealing that water level-fluctuations strongly influenced gross primary production and respiratory rates. Production and respiration changed mainly vertically, clearly in relation to light availability. Gross primary production ranged from 0.15 to 1.26 gO2 m−2 h−1, respiration rate from −0.13 to −0.83 gO2  m−2 h−1 and net primary production from −0.36 to 0.66 gO2  m−2 h −1 within the production layer, which had a mean depth of 5.9 m during the stratification periods and of 6.8 m during the circulations. The greater depth of the mixing layer allowed the consumption of oxygen below the production layer even during the stratifications, when it averaged 10.1 m. Respiration below the production layer ranged from −0.23 to −1.38 gO2 m−2 h−1. Vertically integrated metabolic rates (per unit area) showed their greatest variations at the intra-annual scale (stratification-circulation). Gross primary production and Secchi depth decreased as the mean water level decreased between stratification periods. VB is a highly productive ecosystem; its gross primary production averaged 3.60 gC m−2 d−1 during the 10 years sampled, a rate similar to that of hypertrophic systems. About 45% of this production, an annual average net carbon production of 599 g C m−2 year−1, was exported to the hypolimnion, but on the average 58% of this net production was recycled through respiration below the production layer. Overall, only 19% of the carbon fixed in VB is buried in the sediments. Total ecosystem respiration rates averaged −6.89 gC  m−2 d−1 during 2006–2015, doubling the gross production rates. The reservoir as a whole exhibited a net heterotrophic balance continuously during the decade sampled, which means it has likely been a net carbon source, potentially releasing an average of 3.29 gC m−2 d−1 to the atmosphere. These results are in accordance with recent findings that tropical eutrophic aquatic ecosystems can be stronger carbon sources than would be extrapolated from temperate systems, and can help guide future reassessments on the contribution of tropical lakes and reservoirs to carbon cycles at the global scale. Respiration was positively correlated with temperature both for the stratification periods and among the circulations, suggesting that the contribution of C to the atmosphere may increase as the reservoirs and lakes warm up owing to climate change and as their water level is reduced through intensification of their use as water sources.

The accelerated rate of environmental degradation of the Mexican Caribbean coast is alarming. In this work, spatial analysis procedures were applied to study relationships among wave and wind climates, water quality, and environmental degradation of the principal coastal ecosystems. We found an increasing North-South gradient in the preservation state of the coastal ecosystems, related to the degree of anthropization of the coastline. In the north, all analysed stressors exert high pressure on coral reefs, seagrass meadows, mangroves, and dunes, and cause chronic coastline erosion. The coastal ecosystems of the central and southern regions are more mature and healthier, and the most significant stressor is reduced water quality. The north has been most hit by high-intensity hurricanes, the frequency of which has increased in the Mexican Caribbean over recent decades. The status of conservation of the ecosystems, added to the long-term intensification of environmental pressures, particularly high-intensity hurricanes, will induce further deterioration if a coordinated management scheme is not adopted by decision-makers. To ensure effective coordinated management, plans should be made on a regional scale using shared guidelines. Spatial analysis procedures aid in prioritizing and adapting the shared guidelines depending on the identified major stressors and the preservation state of each region in the Mexican Caribbean.

We continue former work on the modeling of potential effects of Gamma Ray Bursts on Phanerozoic Earth. We focus on global biospheric effects of ozone depletion and model the spectral reduction of light by NO 2 formed in the stratosphere. We also illustrate the current complexities involved in the prediction of how terrestrial ecosystems would respond to this kind of burst. We conclude that more biological field and laboratory data are needed to reach even moderate accuracy in this modeling.

En los años 2001 y 2005, se estudió la composición de las comunidades de octocorales y corales pétreos en el archipiélago de los Jardines de la Reina. Se analizó, en la comunidad de corales pétreos, la incidencia del blanqueamiento ocurrido en el 2005 en el Caribe. Para ello se establecieron doce estaciones de muestreo (siete en el arrecife frontal somero y cinco en el arrecife de cresta), en cada una de estas se estimó la densidad mediante el marco cuadrado de 1 m de lado. En el arrecife frontal somero se identificaron un total de 62 especies (26 de octocorales y 36 de corales), siendo las más abundantes: Pseudopterogorgia americana (2.4 colonias/m2), Eunicea flexuosa (1.1 colonias/m2), Siderastrea siderea (5.0 colonias/m2) y Agaricia agaricites (4.0 colonias/m2). En el arrecife de cresta se identificaron un total de 31 especies (13 de octocorales y 18 de corales), predominando: Briareum asbestinum (1.3 colonias/m2), Porites astreoides (2.5 colonias/m2) y Millepora complanata (1.0 colonias/m2). Las especies más sensibles al blanqueamiento fueron: A. agaricites , Millepora spp. y Montastraea annularis. En sentido general, dicho suceso tuvo una incidencia pobre sobre los corales pétreos. Es menester la ejecución de monitoreos al permitir ajustar los planes de manejo en función de los cambios que puedan ocurrir en la estructura de las comunidades bentónicas.ABSTRACT Octocoral and stony coral communities in the Jardines de la Reina archipelago (Cuba) were studied in 2001 and again in 2005. The incidence of the 2005 bleaching event in the Caribbean was analyzed in the stony coral community. Twelve sampling stations were established: seven in the shallow forereef and five in reef crests, with one square meter quadrants to estimate density. A total of 62 species (26 octocorals and 36 stony corals) were identified in the shallow forereef, including Pseudopterogorgia americana (2.4 colonies/m2), Eunicea flexuosa (1.1 colonies/m2), Siderastrea siderea (5.0 colonies/m2) and Agaricia agaricites (4.0 colonies/m2). In the reef crest, 31 species were identified (13 octocorals and 18 stony corals), with Briareum asbestinum (1.3 colonies/m2), Porites astreoides (2.5 colonies/m2) and Millepora complanata (1.0 colonies/m2) being the most abundant. The most sensitive species to bleaching were: A. agaricites, Millepora spp. and Montastraea annulariS. In general, this event showed a poor incidence with stony corals. Constant monitoring is necessary to adjust the management plan to the changes that may occur in the structure of the benthic communities.

ResumenComo resultado del trabajo de campo realizado en siete comunidades de la provincia de Camagüey, Cuba, sobre el uso popular e indicaciones de plantas medicinales, se presenta información etnobotánica sobre 111 especies de plantas pertenecientes a 96 géneros y a 55 familias. Se obtuvieron 173 indicaciones de uso medicinal, principalmente para afecciones respiratorias, digestivas, hepatobiliares y dermatológicas. Se listaron 116 nombres vernáculos de especies vegetales. Se desconoce la composición química de 39 de las especies y de 18 no se encontraron referencias de su utilización en farmacia. Los datos empíricos obtenidos sobre usos de plantas estimularon la validación farmacológica y toxicológica de algunas de ellas.Palabras clave: Camagüey, Cuba, plantas medicinales. AbstractAn ethnobotanical study has been conducted on traditional medicinal plant uses in seven communities of the Province of Camagüey, Cuba. Ethnobotanical information on 111 plant species from 96 genera and 55 families have been recorded along with 116 different vernacular names. These species are used in the treatment of 173 local health problems (mainly in respiratory, digestive, liver and gallbladder, and skin disorders). Chemistry composition of 39 species is unknown and ethnopharmacological use of 18 species has not been reported previously in the literature. The data collected in this study contribute to the pharmacological and toxicological evaluation of some of the studied species.Key words: Camagüey, Cuba, medicinal plants. IntroducciónCada día se presta más atención al estudio de las plantas medicinales de forma que la etnobotánica, la fitoterapia y la fitoquímica están tomando un auge insospechado, tanto en la práctica de la medicina complementaria como en el ámbito académico. El 80% de la población mundial, más de cuatro mil millones de personas, utiliza las plantas como principal remedio medicinal, según nos señala la OMS. Esta práctica está asociada al empirismo en muchos casos, y faltan estudios químicos, clínicos y epidemiológicos que confirmen de forma fehaciente los efectos fisiológicos de las plantas y los principios activos responsables. No hay que olvidar que el 25% de los fármacos existentes se obtienen de extractos vegetales, o bien se han sintetizado a partir de sustancias halladas en la investigación fitoquímica. Sustancias como la digitalina, la lidocaína, la pilocarpina o la dihidroergocristina son ejemplos de fármacos de uso común que pocas veces se asocian con su origen vegetal (Berdonces & al., 1995).Hoy en día es precisamente en los países del tercer mundo donde la medicina tradicional sobrevive de una forma más auténtica, y esto hace más fácil en dichos países identificar las plantas que necesitan ser científicamente evaluadas. Parece que la distancia entre la medicina tradicional y la ortodoxa empieza a acortarse y que ya no se considera la primera como un obstáculo del progreso científico.La Organización Mundial de la Salud (OMS) estructuró en 1985 un Programa de Medicina Tradicional Herbolaria, reconocie...