Stressed but Stable: Canopy Loss Decreased Species Synchrony and Metabolic Variability in an Intertidal Hard-Bottom Community

The temporal stability of aggregate community properties depends on the dynamics of the component species. Since species growth can compensate for the decline of other species, synchronous species dynamics can maintain stability (i.e. invariability) in aggregate properties such as community abundance and metabolism. In field experiments we tested the separate and interactive effects of two stressors associated with storminess–loss of a canopy-forming species and mechanical disturbances–on species synchrony and community respiration of intertidal hard-bottom communities on Helgoland Island, NE Atlantic. Treatments consisted of regular removal of the canopy-forming seaweed Fucus serratus and a mechanical disturbance applied once at the onset of the experiment in March 2006. The level of synchrony in species abundances was assessed from estimates of species percentage cover every three months until September 2007. Experiments at two sites consistently showed that canopy loss significantly reduced species synchrony. Mechanical disturbance had neither separate nor interactive effects on species synchrony. Accordingly, in situ measurements of CO2-fluxes showed that canopy loss, but not mechanical disturbances, significantly reduced net primary productivity and temporal variation in community respiration during emersion periods. Our results support the idea that compensatory dynamics may stabilise aggregate properties. They further suggest that the ecological consequences of the loss of a single structurally important species may be stronger than those derived from smaller-scale mechanical disturbances in natural ecosystems

Nevoid basal cell carcinoma syndrome (Gorlin syndrome)

Nevoid basal cell carcinoma syndrome (NBCCS), also known as Gorlin syndrome, is a hereditary condition characterized by a wide range of developmental abnormalities and a predisposition to neoplasms

Differences in Circadian Rhythms of Blood Pressure and Heart Rate Among Hypertensive and Normal Blood Pressure Subjects

The purpose of this study was to evaluate the differences in the circadian variations of blood pressure (BP) and heart rate (HR) among three subject groups (hypertensive, normal/high normal and optimal blood pressure). The ambulatory BP and HR of 385 subjects, without clinical evidence of hypertension-related complications, were acquired using a Holter Blood Pressure Monitor and their circadian patterns were analyzed. Systolic, Diastolic and Mean BP showed four different well-de\ufb01ned trends in speci\ufb01c time intervals of the day, similar for the three BP measures and among the three subject groups. Both BP and HR signals presented a decrease between 10:00 and 14:30 and from 19:00 to 2:00 and an increase from 5:00 to 10:00. Between 14:30 and 19:00, BP and HR presented an opposite relationship with decreasing HR and increasing BP, not yet reported in the literature. The behaviors of BP and HR were well approximated in each of the four periods by linear trends in all the three subject groups. On the contrary, in the period between 2:00 and 5:00 both BP and HR showed a quite constant trend. Results support the hypothesis of an independent vagal control during 24-h in respect of HR and BP mean levels, the latter depending on the speci\ufb01c subject group. Moreover, linear approximation in the identi\ufb01ed four intervals could be used to quantify the circadian changes for all kind of subjects