Biological and physical disturbances create the conditions for species succession in any biological ecosystem. In particular, coral reefs are susceptible to this process because of the complexity of their ecological relationships. In the southwest Atlantic, nearshore reefs are mostly coated by a thin layer of coralline crusts rather than stony corals. However, little is known about the succession of crustose coralline algae. We studied this process by means of a series of experimental and control discs exposed to physical disturbance. Our results showed that the dominant species in natural conditions, Pneophyllum conicum, had early recruits and later became dominant on the discs, replicating the community structure of the actual reef. This species had mature reproductive structures and available spores from the beginning of the colonization experiments. Thicker crusts of Porolithon pachydermum and Peyssonnelia sp. were found on the discs after 112 days, and significantly increased their cover over the succeeding months; and after 1 year, P. conicum was less abundant. Physical disturbance increased crust recruitment and the low-light environment created by sediments. The data demonstrated coexistence among crustose coralline species and a tolerance to physical disturbance, which seemed to favor the thinner crusts of P. conicum over thick-crust species during succession. The succession pattern observed in this subtropical Brazilian coral reef differs from that described for shallow tropical reef communities.

ResumenEl alga coralina no geniculada Lithothamnion muelleri Lenormand ex Rosanoff es comúnmente encontrada formando mantos de rodolitos en zonas someras expuestas al oleaje dentro del suroeste del Golfo de California. Esta especie tiene bandas de crecimiento a todo lo largo de las ramas principales del talo que sugieren un crecimiento periódico y que probablemente podrían ser utilizadas para determinar su tasa de crecimiento y edad. Como parte de la investigación que se está desarrollando sobre los mantos de rodolitos y su ecología, se desarrollaron observaciones sobre la naturaleza de esas bandas en la estructura de las plantas y en experimentos de crecimiento en campo y laboratorio. Se marcaron con alizarina plantas individuales de diferentes clases de talla en el campo y otro conjunto de plantas fue al laboratorio llevado para su análisis. La mitad de las plantas fueron muestreadas después de 6 meses y el resto recolectadas a los 12 meses. Los resultados muestran una tasa de crecimiento de 0.60 mm año -1 en el campo y 0.87 mm año -1 en el laboratorio. Los análisis estadísticos mostraron que no existen diferencias significativas entre las ramas de una planta, ni entre plantas de diferentes tamaños. El crecimiento fue estacional, con mayores tasas en invierno y primavera y menores en verano y otoño. Esto puede explicar la alternancia de bandas claras y obscuras (hasta 4) a lo largo de una rama principal. Las tasas de crecimiento sugieren que las plantas más grandes (p.ej. 15 cm de diámetro) podrían tener más de 100 años de antigüedad.Palabras clave: edad, crecimiento, Lithothamnion muelleri, rodolitos, Corallinales. AbstractThe nongeniculate coralline alga Lithothamnion muelleri Lenormand ex Rosanoff is commonly found as a free-living rhodolith in the wave-exposed shallow waters of the southwestern Gulf of California. This species has bands along the main branch axes suggesting that growth is periodic and that may be used to determine age and growth. As part of our ongoing research related to rhodoliths and their ecology, we have made observations on the nature of these bands based on their structure in entire plants and on field and laboratory growth experiments. Individual plants from different size classes were tagged, stained with alizarin and returned to the field, while another set was tested in the laboratory. Half of the plants were sampled after 6 months and the rest after 12 months. The data indicate that this species grew at a rate of 0.60 mm yr -1 in the field and 0.87 mm yr -1 in the laboratory. There were no significant differences among branches within a plant, or among plants of different size. Growth was seasonal, with high rates in winter and spring, and low rates in summer and fall. This may explain the observed alternating light-dark bands (up to 4) along branch axes. The growth rates suggest that larger plants (ca 15 cm diameter) may be over 100 years old.

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The monitoring of surface-water quality followed by water-quality modeling and analysis are essential for generating effective strategies in surface-water-resource management. However, worldwide, particularly in developing countries, water-quality studies are limited due to the lack of a complete and reliable dataset of surface-water-quality variables. In this context, several statistical and machine-learning models were assessed for imputing water-quality data at six monitoring stations located in the Santa Lucía Chico river (Uruguay), a mixed lotic and lentic river system. The challenge of this study is represented by the high percentage of missing data (between 50% and 70%) and the high temporal and spatial variability that characterizes the water-quality variables. The competing algorithms implement univariate and multivariate imputation methods (inverse distance weighting (IDW), Random Forest Regressor (RFR), Ridge (R), Bayesian Ridge (BR), AdaBoost (AB), Hubber Regressor (HR), Support Vector Regressor (SVR) and K-nearest neighbors Regressor (KNNR)). According to the results, more than 76% of the imputation outcomes are considered “satisfactory” (NSE > 0.45). The imputation performance shows better results at the monitoring stations located inside the reservoir than those positioned along the mainstream. IDW was the model with the best imputation results, followed by RFR, HR and SVR. The approach proposed in this study is expected to aid water-resource researchers and managers in augmenting water-quality datasets and overcoming the missing data issue to increase the number of future studies related to the water-quality matter.

The combination of VNB-PTX showed significant activity as first-line chemotherapy for patients with MBC. Myelosuppression was the dose-limiting side effect, whereas neurotoxicity was mild to moderate.