Summary1. Ecologists often measure the biomass and productivity of organisms to understand the importance of populations and communities in the flow of energy through ecosystems. Despite the central role of such studies in the advancement of freshwater ecology, there has been little effort to incorporate parasites into studies of freshwater energy flow. This omission is particularly important considering the roles that parasites sometimes play in shaping community structure and ecosystem processes. 2. Using quantitative surveys and dissections of over 1600 aquatic invertebrate and amphibian hosts, we calculated the ecosystem-level biomass and productivity of trematode parasites alongside the biomass of free-living aquatic organisms in three freshwater ponds in California, USA. 3. Snails and amphibian larvae, which are both important intermediate trematode hosts, dominated the dry biomass of free-living organisms across ponds (snails = 3Á2 g m À2 ;amphibians = 3Á1 g m À2 ). An average of 33Á5% of mature snails were infected with one of six trematode taxa, amounting to a density of 13 infected snails m À2 of pond substrate.Between 18% and 33% of the combined host and parasite biomass within each infected snail consisted of larval trematode tissue, which collectively accounted for 87% of the total trematode biomass within the three ponds. Mid-summer trematode dry biomass averaged 0Á10 g m À2 , which was equal to or greater than that of the most abundant insect orders (coleoptera = 0Á10 g m À2 , odonata = 0Á08 g m À2 , hemiptera = 0Á07 g m À2 and ephemeroptera = 0Á03 g m À2 ). 4.On average, each trematode taxon produced between 14 and 1660 free-swimming larvae (cercariae) infected snail À1 24 h À1 in mid-summer. Given that infected snails release cercariae for 3-4 months a year, the pond trematode communities produced an average of 153 mg m À2 yr À1 of dry cercarial biomass (range = 70-220 mg m À2 yr À1 ). 5.Our results suggest that a significant amount of energy moves through trematode parasites in freshwater pond ecosystems, and that their contributions to ecosystem energetics may exceed those of many free-living taxa known to play key roles in structuring aquatic communities.

No abstract

By infecting multiple host species and acting as a food resource, parasites can affect food web topography and contribute to ecosystem energy transfer. Owing to the remarkable secondary production of some taxa, parasite biomass – although cryptic – can be comparable to other invertebrate and vertebrate groups. More resolved estimates of parasite biomass are therefore needed to understand parasite interactions, their consequences for host fitness, and potential influences on ecosystem energetics. We developed an approach to quantify the masses of helminth parasites and compared our results with those of biovolume-based approaches. Specifically, we massed larval and adult parasites representing 13 species and five life stages of trematodes and cestodes from snail and amphibian hosts. We used a replicated regression approach to quantify dry mass and compared these values with indirect biovolume estimates to test the validity of density assumptions. Our technique provided precise estimates (R2 from 0.69 to 0.98) of biomass across a wide range of parasite morphotypes and sizes. Individual parasites ranged in mass from 0.368 ± 0.041 to 320 ± 98.1 μg. Among trematodes, adult parasites tended to be the largest followed by rediae, with nonclonal larval stages (metacercariae and cercariae) as the smallest. Among similar morphotypes, direct estimates of dry mass and the traditional biovolume technique provided generally comparable estimates (although important exceptions also emerged). Finally, we present generalized length-mass regression equations to calculate trematode mass from length measurements, and discuss the most efficient use of limited numbers of parasites. By providing a novel method of directly estimating parasite biomass while also helping to validate more traditional methods involving length-mass conversion, our findings aim to facilitate future investigations into the ecological significance of parasites, particularly with respect to ecosystem energetics. In addition, this novel technique can be applied to a wide range of difficult-to-mass organisms.

A large majority of clinicians report providing futile/PIC, and such care is associated with measures of clinician well-being, including burnout and intention to quit.

Background The Curamericas/Guatemala Maternal and Child Health Project, 2011–2015, included implementation research designed to assess the effectiveness of an approach referred to as CBIO+ , composed of: (1) the Census-Based, Impact-Oriented (CBIO) Approach, (2) the Care Group Approach, and (3) the Community Birthing Center Approach. This is the second paper in a supplement of 10 articles describing the implementation research and its findings. Paper 1 describes CBIO+ , the Project Area, and how the Project was implemented. Objective This paper describes the implementation research design and details of how it was carried out. Methods We reviewed the original implementation research protocol and the methods used for all data collection related to this Project. The protocol and methods used for the implementation research related to this Project were all standard approaches to the monitoring and evaluation of child survival projects as developed by the United States Agency for International Development Child Survival and Health Grants Program (CSHGP) and the CORE Group. They underwent independent peer review supervised by the CSHGP before the implementation research began. Results The study area was divided into two sets of communities with a total population of 98,000 people. Project interventions were implemented in Area A from 2011 until the end of the project in 2015 (44 months) and in Area B from late 2013 until 2015 (20 months). Thus, Area B served as a quasi-comparison area during the first two years of Project implementation. The overarching study question was whether the CBIO+ Approach improved the health and well-being of children and mothers. The outcome indicators included (1) changes in population coverage of evidence-based interventions, (2) changes in childhood nutritional status, (3) changes in the mortality of children and mothers, (4) quality of care provided at Community Birthing Centers, (5) the impact of the Project on women’s empowerment and social capital, (6) stakeholder assessment of the effectiveness of the CBIO+ Approach, and (7) the potential of wider adoption of the CBIO+ Approach. Conclusion The implementation research protocol guided the assessment of the effectiveness of the CBIO+ Approach in improving the health and well-being of children, mothers, and their communities.