Respuesta de la regeneración natural en manglares del Golfo de Urabá (Colombia) a la variabilidad ambiental y climática intra-anual / Natural regeneration response in mangroves of the Gulf of Urabá (Colombia) to the environmental and intra-annual climate variability

The natural regeneration process allows the mangrove forests remain over time. Both, biological and physical factors can affect the establishment and early stages along the development of trees. This study examined the response of natural regeneration of mangroves in the Turbo River delta and El Uno bay (Urabá Gulf, Colombia) to intra-annual environmental variability. We quantified mortality, survival and recruitment of seedlings of three mangrove species, seasonally during one year, in 72 semi-perma-nent sub-plots of 1m². In the sub-plots, the total height and the diameter at the base of the stem of all mangrove seedlings with basal diameter less than 2.5cm were measured. Damage by herbivores was also recorded to each seedling. While Laguncularia racemosa recorded the highest rates of mortality, Rhizophora mangle showed the highest survival rate during the study period, although Avicennia germinans dominated the natural regeneration. Through a Redundancy Analysis these processes were associated to environmental variables such as: Direct Site Factor-DSF (sunlight), sediments input rate, herbivory, distances from mangroves to the river, to inner lakes, and to the coastline. These variables explained 43% of the natural regeneration variation; sedimentation rate was the most important variable, while light was very representative for the R. mangle survival. Based on historical records of precipitation, Turbo River flow rate and associated sediment loads, it was established that during the highest precipitation peak, the survival of all species decreases and during the dry season, when the conditions of flooding and sediments input were lower, it was improved. The results indicated that the sediments input rates and sunlight play an important role in the survival of natural regeneration of evaluated mangrove species.

En los bosques de mangle, tanto factores biológicos como físicos, afectan el establecimiento y los estados tempranos de desarrollo de los árboles y determinan la distribución espacial de las especies. Se evaluó la respuesta de la regeneración natural de los manglares del delta del río Turbo y la bahía El Uno a la variabilidad ambiental y climática intra-anual. Se cuantificaron la mortalidad, la sobrevivencia y el reclutamiento de las plántulas de tres especies, estacionalmente durante un año. Avicennia germinans dominó la regeneración natural, Rhizophora mangle presentó la mayor la supervivencia y Laguncularia racemosa la mayor mortalidad. Estos procesos se asociaron principalmente con el aporte de sedimentos aluviales, la disponibilidad de luz, la herbivoría, la distancia al río, a las lagunas internas y a la línea de costa, las cuales explicaron el 43% de la variación en la regeneración. La sedimentación fue la variable más importante para el reclutamiento de A. germinans, mientras la luz fue muy representativa para la supervivencia de R. mangle. Con base en registros históricos de precipitación, caudales y carga de sedimentos, se estableció que en la época con mayor precipitación se presenta un descenso en la supervivencia, y en la época seca se favorece el balance entre el reclutamiento y la mortalidad. Los resultados indicaron que la precipitación, el aporte de sedimentos y la luz desempeñan un papel importante en el proceso de la regeneración de las especies evaluadas.

Incidence and prevalence of type 1 diabetes in children aged <15 yr in Castilla-Leon (Spain).

OBJECTIVES: To determine the incidence and prevalence of type 1 diabetes in children younger than 15 yr in the Autonomous Community of Castilla-Leon (Spain). RESEARCH DESIGN AND METHODS: All type 1 diabetic cases with onset at <15 yr of age were recorded during 2003-2004. Identified case subjects were ascertained from several sources and the capture-recapture method was used to estimate the completeness of ascertainment. For prevalence, all patients younger than 15 yr with type 1 diabetes at the beginning and at the end of the study were identified. RESULTS: Over the study period, 130 children aged 0-14 yr were diagnosed with type 1 diabetes. The average observed incidence of type 1 diabetes in this population was 22.22/100 000/yr (95% CI 14.57-29.81). Age-standardized incidence was 22.01/100 000/yr (95% CI 18.18-25.83). The highest incidence was observed in the 5-9 yr age-group (32.45/100 000/yr, 95% CI 24.31-40.59). The prevalence at the beginning and at the end of the study was 1.01/1000 and 1.18/1000, respectively. CONCLUSION: Castilla-Leon appears to have one of the highest incidences of childhood type 1 diabetes in Spain, with recent incidence approaching those of some northern European countries.

Genetic variability among endangered Chinese giant salamanders, Andrias davidianus.

The endangered Chinese giant salamander (Andrias davidianus) is endemic to mainland China. Genetic divergence among six populations of the species was investigated by means of isozyme electrophoresis and mitochondrial DNA (mtDNA) sequences. Forty allozyme loci were resolved for all populations; the amount of genetic divergence among populations was comparable to that in other amphibians. mtDNA sequences showed a similar level of divergence. The population from Huangshan is distinct from other populations, indicating the existence of localized divergence. Both allozyme and mtDNA data failed to associate the populations into a pattern corresponding to the three Chinese river systems, which may be the consequence of human relocation. Conservation policies should emphasize the protection of localized populations and cessation of human-facilitated introductions. Future studies should focus on investigating the divergence among localized populations from isolated mountain regions, particularly using more fine-grained techniques such as microsatellite DNA.