In an analysis of data from the CESAME cohort in France, patients with anal and/or perianal Crohn's disease have a high risk of anal cancer, including perianal fistula-related cancer, and a high risk of rectal cancer.

No abstract

Fish ponds host a relatively important share of the breeding population of waterfowl in Europe. The objective of this study was to investigate the influence of fish-farming management on the distribution of dabbling and diving duck breeding, in 103 fishponds from four regions important for duck breeding in France. Duck breeding in fish ponds was apparently influenced by food resource and nesting site availability. Dabbling duck pair density was generally higher when invertebrates were abundant in macrophytes beds and when competition for food with carps Cyprinus carpio was potentially decreased by lower fish stock biomass. Diving duck pair abundance seemed to be negatively influenced by low invertebrates biomasses in pond sediment and by the absence of large reed beds at the edge of waterbodies. The difference between dabbling and diving ducks was also confirmed by a study of the variation in brood numbers standardized by pair numbers. This brood:pair ratio corresponded to a measure of nesting success and the possible attraction of fish ponds for some broods hatched in neighbouring waterbodies. Dabbling duck brood:pair ratio was lower in one of the study regions where most of meadow areas surrounding fish ponds have been transformed into cereal crops in the past few decades. Diving duck brood:pair ratio was positively linked to pond fertilization due to fish farming. Fish farming, therefore, influenced duck breeding by an interaction between carp density and fertilization. We hypothesize that fertilization increases zooplankton density, thereby decreasing the competition between carps and waterfowl for benthic prey.

Fishponds are artificial ecosystems in which biodiversity may be strongly affected by fish farming management. We studied biodiversity variation along a gradient of fish farming intensification within a 180-pond sample of a French region to establish whether biodiversity primarily depended on extensive management with the alternative hypothesis that some habitat characteristics could compensate for the effect of intensification. We compared the relationships of three biodiversity indicators (breeding birds, protected plants, macrophytes) to an index of intensification and to habitat characteristics likely to influence each indicator. In all selected indicators, species richness did not vary according to the composite intensification gradient. Protected plant richness was best explained by periodic drainage, which could thus benefit biodiversity in intensified fishponds provided that shallow littoral areas are still present. Bird richness was linked to macrophyte cover and probably to reed bed areas. Macrophyte richness and coverage were negatively influenced by low water transparency and high fish biomass which seemed likely to affect bird habitat above 350-400 kg/ha. Aquatic vegetation, which may reflect interactive effects of environmental factors and fish farming management, may then contribute to assessment of the ecological status of fishponds under the E.U. Water Framework Directive.

Agri-environment schemes usually assume that suitable management in patches of grassland habitat may benefit bird populations in improving the overall demographic balance. In this study, we investigate the hypothesis that nesting site fidelity after previous breeding success might lead meadow birds to select late mown fields where the risk of breeding failure is lower. It was carried out in 4 study areas of the Mézenc volcanic massif (south-east of France) within the altitude range 1,150-1,350 m. Meadow passerine territories were defined by the territory mapping method, and reproductive success in Whinchat Saxicola rubetra territories was assessed by the observation of prey carrying and juveniles just leaving nests. A comparison of models led us to consider that territorial birds selected hay fields under the influence of grass structure rather than through a theoretical successful experience of late mowing. Higher territory density was observed in fields with dense grass cover C50 cm which were usually more fertilized ([75 kg ha -1 nitrogen per year) and mown earlier. In 3 study sites, however, the rate of nesting failure due to mowing was lower than expected under the hypothesis of randomly distributed nesting sites, suggesting that the risk was not ignored by territorial birds. Within each study site, we also observed higher invertebrate abundance during the chick feeding period in fields with high bird territory density. ZusammenfassungWählen Singvögel des Offenlandes aufgrund von erhöhtem Bruterfolg spät gemähte Felder? Agrar-Umweltprogramme gehen normalerweise von der Annahme aus, dass Vogelpopulationen von geeigneten Managementmaßnahmen auf fleckenarteigen Teilflächen des Graslands profitieren könnten, weil durch sie die demographische Bilanz insgesamt verbessert würde. In der vorliegenden Studie bearbeiten wir die Hypothese, dass Nestortstreue nach vorherigem Bruterfolg Wiesenbrüter dazu führt, spät gemähte Felder auszuwählen, auf denen das Brutverlust-Risiko geringer ist. Die Studie wurde auf vier Teilflächen des Mézenc Vulkanmassivs (Südost-Frankreich) in Höhenlagen von 1,150-1,350 m durchgeführt. Die Brutreviere von wiesenbrütenden Singvögeln wurden mit Hilfe einer Revierkartierungsmethode erfasst, und der Reproduktionserfolg in Revieren des Braunkehlchens Saxicola rubetra durch Beobachtung Futter tragender Altvögel und gerade flügger Jungvögel bestimmt. Ein Vergleich von Modellen führte uns zu dem Schluss, dass territoriale Vögel Wiesen für die Heuernte eher unter dem Einfluss der Vegetationsstruktur auswähl-ten, als unter dem Aspekt einer theoretisch erfolgreichen Bruterfahrung durch späte Mahd. Eine höhere Revierdichte konnte vor allem in Feldern mit dichter Grasbedeckung C50 cm beobachtet werden, die normalerweise besser gedüngt waren ([75 kg ha -1 Stickstoff pro Jahr) und früher gemäht wurden. In drei Untersuchungsflächen war die Brutverlustrate durch Mähen allerdings niedriger, als Communicated by F. Bairlein.