The database of the PREDICTS (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems) project

The PREDICTS project-Projecting Responses of Ecological Diversity In Changing Terrestrial Systems (www.predicts.org.uk)-has collated from published studies a large, reasonably representative database of comparable samples of biodiversity from multiple sites that differ in the nature or intensity of human impacts relating to land use. We have used this evidence base to develop global and regional statistical models of how local biodiversity responds to these measures. We describe and make freely available this 2016 release of the database, containing more than 3.2 million records sampled at over 26,000 locations and representing over 47,000 species. We outline how the database can help in answering a range of questions in ecology and conservation biology. To our knowledge, this is the largest and most geographically and taxonomically representative database of spatial comparisons of biodiversity that has been collated to date; it will be useful to researchers and international efforts wishing to model and understand the global status of biodiversity.

Resource Utilization After Ankle Arthritis Surgery

Category:

Ankle Arthritis

Introduction/Purpose:

As an alternative to ankle replacement, ankle arthrodesis remains a mainstay in the treatment of end- stage arthritis. Arthroscopic techniques for ankle arthrodesis have more recently been developed, although there has been limited research exploring the cost of arthroscopic (AAA) versus open ankle arthrodesis (OAA), and comparing ankle fusions to replacement (TAA). We hypothesize that resource use after AAA will be lower than that after OAA, and both will be lower than TAA.

Methods:

We performed a retrospective review of a prospectively collected database. The COFAS database was used to identify patients with >2 years of follow up who have undergone AAA, OAA or Hintegra TAA at St Paul’s Hospital between 2003-2010. Ninety patients with TAA, 52 with AAA and 56 with OAA met our inclusion criteria. The following data were documented: patient demographics (age, gender, presence of diabetes, inflammatory arthritis or any smoking history), factors related to the index surgery (type of surgery, OR time, length of stay) and factors relating to the post-operative course (number of unplanned post-operative clinic visits, OR time for re-operations, length of stay for additional hospital admissions). For all significant comparisons, p < 0.05.

Results:

AAA required less primary surgery OR time and shorter primary hospital stay vs. TAA and OAA. Patients required more additional follow-up visits for TAA and OAA vs. AAA. TAA required more additional days in hospital compared to OAA or AAA. For each primary TAA, on average an additional seven clinic visits, 60 minutes of revision surgery, three days in hospital were required on top of the cost assigned for the primary arthroplasty. For each primary AAA, an additional four clinic visits, 23 minutes of revision surgery and one day in hospital were required. For each primary OAA, an average additional five clinic visits, three minutes of revision OR time, and 0.2 days of additional hospital stay were required.

Conclusion:

Using several measures of resource use, we find that arthroscopic ankle fusions compare favourably to both ankle replacements and open ankle fusions. We also show that resource utilization measurements can be a useful surrogate for complications, and that resource utilization can demonstrate the practical implications of complications for patients, surgeons and health care providers or payers.

Temporal trends in the treatment of severe traumatic hemorrhage

BACKGROUND

This study examined the evolution of damage control resuscitation (DCR) and outcomes in severe traumatic hemorrhage (STH) at a large Canadian trauma center.

METHODS

This was a retrospective cohort study of trauma patients admitted to a level 1 trauma center between 2005 and 2010, who received 10 or more units of packed red blood cells within 24 hours of admission. Demographic and clinical findings were compared between survivors and nonsurvivors.

RESULTS

Forty-five patients were included. Twenty-five percent of patients were coagulopathic at admission. Early crystalloid use declined over the study period. The mean 24-hour fresh-frozen plasma:platelets:packed red blood cells ratio was 1:1:2. Hemorrhage-related mortality was 69%. No pedestrians survived STH. A total of 1,032 blood product units were used in the first day for nonsurvivors.

CONCLUSIONS

Principles of DCR crept into clinical practice even before the implementation of a formal STH protocol. DCR appeared to reduce the intensive care unit length of stay but not mortality. STH is associated with heavy use of blood bank resources and high mortality rates. Futility of resuscitative efforts may be predictable by mechanism and early physiological markers.

Herbivore metabolism and stoichiometry each constrain herbivory at different organizational scales across ecosystems

Plant-herbivore interactions mediate the trophic structure of ecosystems. We use a comprehensive data set extracted from the literature to test the relative explanatory power of two contrasting bodies of ecological theory, the metabolic theory of ecology (MTE) and ecological stoichiometry (ES), for per-capita and population-level rates of herbivory across ecosystems. We found that ambient temperature and herbivore body size (MTE) as well as stoichiometric mismatch (ES) both constrained herbivory, but at different scales of biological organization. Herbivore body size, which varied over 11 orders of magnitude, was the primary factor explaining variation in per-capita rates of herbivory. Stoichiometric mismatch explained more variation in population-level herbivory rates and also in per-capita rates when we examined data from within functionally similar trophic groups (e.g. zooplankton). Thus, predictions from metabolic and stoichiometric theories offer complementary explanations for patterns of herbivory that operate at different scales of biological organization.

A cross-system synthesis of consumer and nutrient resource control on producer biomass

Nutrient availability and herbivory control the biomass of primary producer communities to varying degrees across ecosystems. Ecological theory, individual experiments in many different systems, and system-specific quantitative reviews have suggested that (i) bottom-up control is pervasive but top-down control is more influential in aquatic habitats relative to terrestrial systems and (ii) bottom-up and top-down forces are interdependent, with statistical interactions that synergize or dampen relative influences on producer biomass. We used simple dynamic models to review ecological mechanisms that generate independent vs. interactive responses of community-level biomass. We calibrated these mechanistic predictions with the metrics of factorial meta-analysis and tested their prevalence across freshwater, marine and terrestrial ecosystems with a comprehensive meta-analysis of 191 factorial manipulations of herbivores and nutrients. Our analysis showed that producer community biomass increased with fertilization across all systems, although increases were greatest in freshwater habitats. Herbivore removal generally increased producer biomass in both freshwater and marine systems, but effects were inconsistent on land. With the exception of marine temperate rocky reef systems that showed positive synergism of nutrient enrichment and herbivore removal, experimental studies showed limited support for statistical interactions between nutrient and herbivory treatments on producer biomass. Top-down control of herbivores, compensatory behaviour of multiple herbivore guilds, spatial and temporal heterogeneity of interactions, and herbivore-mediated nutrient recycling may lower the probability of consistent interactive effects on producer biomass. Continuing studies should expand the temporal and spatial scales of experiments, particularly in understudied terrestrial systems; broaden factorial designs to manipulate independently multiple producer resources (e.g. nitrogen, phosphorus, light), multiple herbivore taxa or guilds (e.g. vertebrates and invertebrates) and multiple trophic levels; and - in addition to measuring producer biomass - assess the responses of species diversity, community composition and nutrient status.

Consumer versus resource control of producer diversity depends on ecosystem type and producer community structure

Consumer and resource control of diversity in plant communities have long been treated as alternative hypotheses. However, experimental and theoretical evidence suggests that herbivores and nutrient resources interactively regulate the number and relative abundance of coexisting plant species. Experiments have yielded divergent and often contradictory responses within and among ecosystems, and no effort has to date reconciled this empirical variation within a general framework. Using data from 274 experiments from marine, freshwater, and terrestrial ecosystems, we present a cross-system analysis of producer diversity responses to local manipulations of resource supply and/or herbivory. Effects of herbivory and fertilization on producer richness differed substantially between systems: (i) herbivores reduced species richness in freshwater but tended to increase richness in terrestrial systems; (ii) fertilization increased richness in freshwater systems but reduced richness on land. Fertilization consistently reduced evenness, whereas herbivores increased evenness only in marine and terrestrial ecosystems. Producer community evenness and ecosystem productivity mediated fertilization and herbivore effects on diversity across ecosystems. Herbivores increased producer richness in more productive habitats and in producer assemblages with low evenness. These same assemblages also showed the strongest reduction in richness with fertilization, whereas fertilization increased (and herbivory decreased) richness in producer assemblages with high evenness. Our study indicates that system productivity and producer evenness determine the direction and magnitude of top-down and bottom-up control of diversity and may reconcile divergent empirical results within and among ecosystems.

Predators accelerate nutrient cycling in a bromeliad ecosystem

Conventional ecological theory predicts that predators affect nutrient cycling by decreasing the abundance or activity of prey. By using a predator-detritivore-detritus food chain in bromeliads, we show that predators can increase nutrient cycling by a previously undescribed, but broadly applicable, mechanism: reducing nutrient export by prey emigration. Contrary to expectations, predation on detritivores increases detrital nitrogen uptake by bromeliads. Predation reduces detritivore emergence and hence export of nitrogen from the system. Detritivores therefore benefit their host plant, but only when predators are present. More generally, our results show that predator loss or extinction can dramatically and unexpectedly affect ecosystem functioning.