Availability of receptive females at the mating place and mating chances of males in the dragonfly Aeschna cyanea

Summary The females of the dragonfly Aeschna cyanea visiting ponds vary in their receptiveness to males waiting there. Individual males pay several short visits to a mating place in the course of a day, searching for receptive females. Non-receptive females prefer to oviposit at the pond in the evening, whereas receptive females arrive throughout the day. The highest number of receptive females is found on warm days during the afternoon at which time the greatest number of copulations occur. However, as the number of males and, therefore, the competition between males is also highest during these periods, the mating chances of a particular male are constant throughout the day.     

Evaluation of beach quality as perceived by users

Recreational beaches are strategic ecosystems for tourism and should be used in a sustainable manner. We studied three beaches in the municipality of Guaymas (NW Mexico), in order to assess their beach quality and identify key management issues. The evaluation was based on the perceptions of users concerning: (1) the user profile; (2) the recreational habits of users; and (3) the biophysical characteristics, infrastructure, services, and cleanliness of each beach. The results showed that the beaches were of different quality. The key management issues identified were the need to design and apply specific management programs for each beach, specifically in regards to improving infrastructure and services, and obtaining certification as a sustainable beach. The evaluation of the beaches as perceived by users suggests that it would be useful to assess beach quality in order to support management goals and be applicable to other beaches, both nationally and internationally.     

Bitte wenden Sie jetzt – Das Auto der Zukunft von Eckard Helmers WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Oktober 2009. ISBN: 978-3-527-32648-8. 204 Seiten, gebunden. €?24,90. http://www.wiley-vch-macht-neugierig.de/02_helmers/buch/bitte_wenden.php

Eckard Helmers rekapituliert die Geschichte des Automobils von den ersten Prototypen bis zum „?lschock“ 2008 und stellt ausführlich dar, um welche Schadstoffe Politiker, Lobbyisten und Umweltschützer seit Jahren streiten und welche alternativen Antriebe es bereits gibt. Detailliert wird erkl?rt, was beim Autokauf zu beachten ist, wenn man einen Beitrag zum Erhalt der Umwelt leisten m?chte. Schlie?lich entwirft Helmers eine mobile Zukunftsvision, in der Elektroantriebe eine zentrale Rolle spielen. Sein Buch ist ein engagiertes Pl?doyer für einen grundlegenden Bewusstseinswandel.