Filtration rate in seven Scandinavian ascidians: implications of the morphology of the gill sac

The ascidian branchial basket is functionally responsible for pumping water through the animal. Within Ascidiacea the branchial basket and the stigmata are morphologically variable and these features are important taxonomical characters. However, the functional significance of this morphological variation has not been studied in great detail. Here, we have measured filtration rates in seven ascidians: Clavelina lepadiformis (Order Aplousobranchiata); Ciona intestinalis, Corella parallelogramma, Ascidia virginea (Order Phlebobranchiata); Boltenia echinata, Molgula manhattensis, Pyura tessellata (Order Stolidobranchiata) and compared these rates with the morphological characteristics of the branchial basket and the stigmata. Filtration rates were measured in the laboratory and determined from an exponential reduction in algal cell (Rhodomonas sp.) concentration as a function of time. The branchial baskets of the experimental ascidians were dissected free and photographs were taken of the entire basket and of the stigmata. It was found that filtration rates in the investigated ascidians are determined primarily by the area of the branchial basket and the length of the ciliary band lining the stigmatal openings, and that the form of the stigmatal opening has no impact on filtration rates.     

Diffusion of US army chemical weapons disposal technologies: public perception of technology attributes

This study was conducted to identify factors that influence individuals' acceptance of environmental management technologies for cleaning up hazardous materials. The study sample consisted of approximately 2600 residents living within emergency response zones surrounding eight US Army's Chemical Weapons Stockpile sites. The findings suggest that residents perceive clear differences between the desirable characteristics of the two technologies: incineration and neutralization. In a relative comparison, the majority of positive technological attributes were associated with incineration. Positive perceptions toward incineration were associated with individuals who trust the Army, who perceive that the media have made them more trusting of weapons disposal activities, who are ready to participate, and who are male. Unlike incineration, there was insufficient evidence that individual factors influence variations in perceptions toward neutralization. No community factor was related to perceptions toward either incineration or neutralization.