Phantom midges are characteristic inhabitants of standing waters and are well known for their diel migrations. Despite the extensive body of literature covering their ecology, there are still ...knowledge gaps with regards to the factors that determine their distribution. Furthermore, although spatial and temporal segregation patterns among chaoborids have long been reported, the prevalence of such patterns in shallow waters remains unclear. We investigated the distribution of Chaoborus species, as well as their spatial and temporal segregation and diel mesohabitat migration, in the NE Iberian Peninsula. We detected three Chaoborus species (C. crystallinus, C. pallidus and C. flavicans), with the latter being the most dominant, and co-occurrences among these species being very low. C. flavicans did not perform diel horizontal migrations, although in one of the ponds it showed high affinities to vegetated areas during both day- and night-time, similar to its potential predators. Therefore, although we did not observe the role of diel horizontal migrations as an antipredator mechanism in shallow water bodies, aquatic vegetation could confer refuge to the chaoborid larvae.Original Abstract: Las larvas del genero Chaoborus son unos habitantes tipicos de aguas estancadas con unos patrones muy marcados de migracion vertical diaria. Aunque existe una extensa bibliografia de su papel ecologico y biologico, existen aun algunos interrogantes en relacion a su distribucion. Ademas, aunque los patrones de segregacion espacial y temporal en los caoboridos estan bien documentados, en aguas someras siguen sin estar claros. Nuestro estudio se centra en la distribucion de las especies del genero Chaoborus en el NE de la Peninsula Iberica, su segregacion espacial y temporal y las migraciones diarias entre mesohabitats. Se detectaron tres especies del genero Chaoborus (C. crystallinus, C. pallidus y C. flavicans), siendo la ultima la mas abundante, y unas coocurrencias entre estas especies muy bajas. C. flavicans no mostro ninguna migracion diaria horizontal, aunque en una de las charcas presento una afinidad mayor por las zonas vegetadas tanto de dia como de noche, al igual que sus predadores potenciales. Por lo que, aunque no se observaron patrones de migracion horizontal diaria como mecanismo antipredador en masas de agua someras, la vegetacion acuatica podria suponer un refugio para las larvas de Chaoborus.
Among relatives of parturients of Majorca island a statistically higher prevalence of HBV markers was found among children (22.8%) and husbands (43.8%) of 49 HBsAg chronic carriers as compared to ...2.7% and 19.2%, respectively, among the corresponding relatives of 79 susceptible controls. Prevalence of the carrier state was 0% among both children and husbands of susceptible women, 2.1% (NS) and 11.4% (p less than 0.0001) among husbands and children, respectively, of chronic carrier parturients with a proportion of chronic antigenemia among subjects with HBV markers, that reaches 50% in children and only 4.8% (p less than 0.01) in adults. Following active-passive immunization, an active response of anti-HBs (3.4%), and HBsAg (1.7%), was achieved, after 12 months of follow-up, in 59 newborns of chronic carrier parturients. Detection of HBsAg prior to delivery as well as immunization both of newborns and susceptible household contacts of chronic carrier mothers should become general.
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