Temporal variability of a protected multispecific tropical seagrass meadow in response to environmental change.

In a changing environment, there is an increasing interest to monitor ecosystems to understand their responses to environmental change. Seagrass meadows are highly important ecosystems that are under constant pressure from human activities and climate impacts, with marked declines observed worldwide. Despite increasing efforts, monitoring of multispecific tropical seagrass meadows is scarce, particularly in low-income regions. Based on data from a monitoring programme in a marine protected area in Zanzibar (Tanzania), we assessed temporal changes in seagrass cover and species composition during a 10-year period in relation to local variability in environmental variables. We observed a strong, gradual decline in seagrass cover and changes in species composition, followed by a period of recovery. However, the timing and length of these temporal patterns varied in space (between transects). Multiple environmental variables-cloud cover, temperature, storm occurrence, sunspot activity, and tidal amplitude and height-influenced seagrass cover, although only to a minor extent, suggesting that the monitored seagrass meadow may be influenced by other unmeasured factors (e.g. water currents and sediment movement). Our results show that seagrass meadows can be highly dynamic at small (10-50 m) spatial scales, even in the absence of major local anthropogenic impacts. Our findings suggest that high-resolution monitoring programmes can be highly valuable for the detection of temporal changes in multispecific seagrass meadows; however, to understand the causes of change, there is a need of long-term (> 10 years) data series that include direct measurements of environmental variables and extreme events.

Density-dependent positive feedbacks buffer aquatic plants from interactive effects of eutrophication and predator loss.

Self-facilitation allows populations to persist under disturbance by ameliorating experienced stress. In coastal ecosystems, eutrophication and declines of large predatory fish are two common disturbances that can synergistically impact habitat-forming plants by benefitting ephemeral algae. In theory, density-dependent intraspecific plant facilitation could weaken such effects by ameliorating the amount of experienced stress. Here, we tested whether and how shoot density of a common aquatic plant (Myriophyllum spicatum) alters the response of individual plants to eutrophication and exclusion of large predatory fish, using a 12-week cage experiment in the field. Results showed that high plant density benefitted individual plant performance, but only when the two stressors were combined. Epiphytic algal biomass per plant more than doubled in cages that excluded large predatory fish, indicative of a trophic cascade. Moreover, in this treatment, individual shoot biomass, as well as number of branches, increased with density when nutrients were added, but decreased with density at ambient nutrient levels. In contrast, in open cages that large predatory fish could access, epiphytic algal biomass was low and individual plant biomass and number of branches were unaffected by plant density and eutrophication. Plant performance generally decreased under fertilization, suggesting stressful conditions. Together, these results suggest that intraspecific plant facilitation occurred only when large fish exclusion (causing high epiphyte load) was accompanied by fertilization, and that intraspecific competition instead prevailed when no nutrients were added. As coastal ecosystems are increasingly exposed to multiple and often interacting stressors such as eutrophication and declines of large predatory fish, maintaining high plant density is important for ecosystem-based management.

A cross-scale trophic cascade from large predatory fish to algae in coastal ecosystems.

Trophic cascades occur in many ecosystems, but the factors regulating them are still elusive. We suggest that an overlooked factor is that trophic interactions (TIs) are often scale-dependent and possibly interact across spatial scales. To explore the role of spatial scale for trophic cascades, and particularly the occurrence of cross-scale interactions (CSIs), we collected and analysed food-web data from 139 stations across 32 bays in the Baltic Sea. We found evidence of a four-level trophic cascade linking TIs across two spatial scales: at bay scale, piscivores (perch and pike) controlled mesopredators (three-spined stickleback), which in turn negatively affected epifaunal grazers. At station scale (within bays), grazers on average suppressed epiphytic algae, and indirectly benefitted habitat-forming vegetation. Moreover, the direction and strength of the grazer-algae relationship at station scale depended on the piscivore biomass at bay scale, indicating a cross-scale interaction effect, potentially caused by a shift in grazer assemblage composition. In summary, the trophic cascade from piscivores to algae appears to involve TIs that occur at, but also interact across, different spatial scales. Considering scale-dependence in general, and CSIs in particular, could therefore enhance our understanding of trophic cascades.

Association between anticoagulant therapy, exacerbations and mortality in a Danish cohort of patients with Chronic Obstructive Pulmonary Disease.

OBJECTIVES: Pulmonary Embolism has been frequently reported in Acute Exacerbations of Chronic Obstructive Pulmonary Disease (AE-COPD). The study aimed to determine whether COPD patients who receive anticoagulant (AC) therapy have a reduced risk of hospitalization due to AE-COPD and death. METHODS: This nationwide population-based study was based on data from the Danish Register of COPD (DrCOPD), which contains complete data on COPD outpatients between 1st January 2010 and 31st December 2018. National registers were used to obtain information regarding comorbidities and vital status. Propensity-score matching and Cox proportional hazards models were used to assess AE-COPD and death after one year. RESULTS: The study cohort consisted of 58,067 patients with COPD. Of these, 5194 patients were on AC therapy. The population was matched 1:1 based on clinical confounders and AC therapy, resulting in two groups of 5180 patients. We found no association between AC therapy and AE-COPD or all-cause mortality in the propensity-score matched population (HR 1.03, 95% CI 0.96-1.10, p = 0.37). These findings were confirmed in a competing risk analysis. In the sensitivity analysis, we performed an adjusted analysis of the complete cohort and found a slightly increased risk of AE-COPD or death in patients treated with AC therapy. This study found a low incidence of pulmonary embolisms and deep venous thrombosis in both groups. CONCLUSIONS: AC therapy was not associated with the risk of hospitalization due to AE-COPD or all-cause mortality.

Pseudomonas aeruginosa and risk of death and exacerbations in patients with chronic obstructive pulmonary disease: an observational cohort study of 22 053 patients.

OBJECTIVES: The role of Pseudomonas aeruginosa in the long-term prognosis of chronic obstructive pulmonary disease (COPD) is unknown. The purpose of this study was to determine whether P. aeruginosa is associated with increased risk of exacerbations or death in patients with COPD. METHODS: This is a multiregional epidemiological study based on complete data on COPD outpatients between 1 January 2010 and 31 October 2017 and corresponding microbiology and national register data. Time-dependent Cox proportional hazards models and propensity matching was used to estimate hospitalization-demanding exacerbations and death after 2 years, separately and in combination. RESULTS: A total of 22 053 COPD outpatients were followed for a median of 1082 days (interquartile-range: 427-1862). P. aeruginosa was present in 905 (4.1%) patients. During 730 days of follow-up, P. aeruginosa strongly and independently predicted an increased risk of hospitalization for exacerbation or all-cause death (HR 2.8, 95%CI 2.2-3.6; p <0.0001) and all-cause death (HR 2.7, 95%CI 2.3-3.4; p <0.0001) in analyses adjusted for known and suspected confounders. The signal remained unchanged in unadjusted analyses as well as propensity-matched subgroup analyses. Among patients 'ever colonized' with P. aeruginosa, the incidence of hospital-demanding exacerbations doubled after the time of the first colonization. CONCLUSIONS: COPD patients in whom P. aeruginosa can be cultured from the airways had a markedly increased risk of exacerbations and death. It is still not clear whether this risk can be reduced by offering patients targeted antipseudomonal antibiotics. A randomized trial is currently recruiting patients to clarify this (ClinicalTrials.gov: NCT03262142).

[Patient preferences or cost-effectiveness? Priorities are highly affected by introduction of economic dimension]. / Patientönskemål eller kostnadseffektivitet? Prioriteterna påverkas högst påtagligt då en ekonomisk dimension införs.

In recent years various methods to measure patient satisfaction have been applied as part of quality improvement programmes in the health services. However, the statistical quality as well as the applicability and change-orientation of the methods have been questioned. Furthermore, most methods pay no attention to economic aspects. Even a methodologically well-founded measurement of patient satisfaction may lead to wrong conclusions unless economic consequences are taken into consideration. It is possible to carry out an integrated analysis that includes patient preferences as well as economic aspects.