Food-web structure in relation to environmental gradients and predator-prey ratios in tank-bromeliad ecosystems

Little is known of how linkage patterns between species change along environmental gradients. The small, spatially discrete food webs inhabiting tank-bromeliads provide an excellent opportunity to analyse patterns of community diversity and food-web topology (connectance, linkage density, nestedness) in relation to key environmental variables (habitat size, detrital resource, incident radiation) and predators: prey ratios. We sampled 365 bromeliads in a wide range of understorey environments in French Guiana and used gut contents of invertebrates to draw the corresponding 365 connectance webs. At the bromeliad scale, habitat size (water volume) determined the number of species that constitute food-web nodes, the proportion of predators, and food-web topology. The number of species as well as the proportion of predators within bromeliads declined from open to forested habitats, where the volume of water collected by bromeliads was generally lower because of rainfall interception by the canopy. A core group of microorganisms and generalist detritivores remained relatively constant across environments. This suggests that (i) a highly-connected core ensures food-web stability and key ecosystem functions across environments, and (ii) larger deviations in food-web structures can be expected following disturbance if detritivores share traits that determine responses to environmental changes. While linkage density and nestedness were lower in bromeliads in the forest than in open areas, experiments are needed to confirm a trend for lower food-web stability in the understorey of primary forests

Environmental determinants of macroinvertebrate diversity in small water bodies: insights from tank-bromeliads

The interlocking leaves of tank-forming bromeliads (Bromeliaceae) collect rainwater and detritus, thus creating a freshwater habitat for specialized organisms. Their abundance and the possibility of quantifying communities with accuracy give us unparalleled insight into how changes in local to regional environments influence community diversity in small water bodies. We sampled 365 bromeliads (365 invertebrate communities) along a southeastern to northwestern range in French Guiana. Geographic locality determined the species pool for bromeliad invertebrates, and local environments determined the abundance patterns through the selection of traits that are best adapted to the bromeliad habitats. Patterns in community structure mostly emerged from patterns of predator species occurrence and abundance across local-regional environments, while the set of detritivores remained constant. Water volume had a strong positive correlation with invertebrate diversity, making it a biologically relevant measure of the pools' carrying capacity. The significant effects of incoming detritus and incident light show that changes in local environments (e.g., the conversion of forest to cropping systems) strongly influence freshwater communities. Because changes in local environments do not affect detritivores and predators equally, one may expect functional shifts as sets of invertebrates with particular traits are replaced or complemented by other sets with different traits

Outpatient chemotherapy with gemcitabine and oxaliplatin in patients with biliary tract cancer

This phase II study was conducted to determine the efficacy and toxicity of a gemcitabine (GEM) and oxaliplatin (OX) chemotherapy protocol in patients with unresectable biliary tract cancer (BTC). Patients were treated with GEM 1000 mg m−2 (30 min infusion) on days 1, 8, 15, and OX 100 mg m−2 (2 h infusion) on days 1 and 15 (gemcitabine and oxaliplatin (GEMOX-3 protocol), repeated every 28 days. The data were collected according to the Simon 2-stage design for a single centre phase II study (α=0.05; β=0.2). Primary end point was response rate; secondary end points were time-to-progression (TTP), median survival, and safety profile. Thirty-one patients were enrolled in the study between July 2002 and April 2005. Therapeutic responses were as follows: partial response in eight patients (26%, 95% confidence interval (CI) 14–44), stable disease in 14 patients (45%, 95%CI 29–62), resulting in a disease control rate of 71%. Nine patients (29%, 95%CI 16–47) had progressive disease. Median TTP was 6.5 months. Median overall survival was 11 months. Common Toxicity Criteria (CTC) Grade 3–4 toxicities were transient thrombocytopenia (23%), peripheral sensory neuropathy (19%), leucopenia (16%), and anaemia (10%). In conclusion the GEMOX-3 protocol is active and well tolerated in patients with advanced BTC. It can be applied in an outpatient setting with three visits per month only

The ecological role of ponds in a changing world

The fifth conference of the European Pond Conservation Network (Luxembourg, June 2012) brought together researchers, environmental managers, and other stakeholders with the aim to share stateof-the-art knowledge on the ecology, management, and conservation of ponds in the context of the many challenges facing the wider water environment. Although well-known ecological patterns apply to most ponds in Europe and elsewhere, recent data highlight that part of the environmental variables governing pond biodiversity remain specific to climatic/ biogeographic regions and to elevation ranges, suggesting that, in addition to common practice, management plans should include range-specific measures. Beyond the contribution of individual ponds to the aquatic and terrestrial life, connected networks of ponds are vital in the provision of new climate space as a response to global climate change, by allowing the observed northward and/or upward movements of species. In terms of services, ponds offer sustainable solutions to key issues of water management and climate change such as nutrient retention, rainfall interception, or carbon sequestration. While the ecological role of ponds is now well established, authoritative research-based advice remains needed to inform future direction in the conservation of small water bodies and to further bridge the gap between science and practice

The ecological role of ponds in a changing world

The fifth conference of the European Pond Conservation Network (Luxembourg, June 2012) brought together researchers, environmental managers, and other stakeholders with the aim to share stateof-the-art knowledge on the ecology, management, and conservation of ponds in the context of the many challenges facing the wider water environment. Although well-known ecological patterns apply to most ponds in Europe and elsewhere, recent data highlight that part of the environmental variables governing pond biodiversity remain specific to climatic/ biogeographic regions and to elevation ranges, suggesting that, in addition to common practice, management plans should include range-specific measures. Beyond the contribution of individual ponds to the aquatic and terrestrial life, connected networks of ponds are vital in the provision of new climate space as a response to global climate change, by allowing the observed northward and/or upward movements of species. In terms of services, ponds offer sustainable solutions to key issues of water management and climate change such as nutrient retention, rainfall interception, or carbon sequestration. While the ecological role of ponds is now well established, authoritative research-based advice remains needed to inform future direction in the conservation of small water bodies and to further bridge the gap between science and practice