A three-stage symbiosis forms the foundation of seagrass ecosystems

Seagrasses evolved from terrestrial plants into marine foundation species around 100 million years ago. Their ecological success, however, remains a mystery because natural organic matter accumulation within the beds should result in toxic sediment sulfide levels. Using a meta-analysis, a field study, and a laboratory experiment, we reveal how an ancient three-stage symbiosis between seagrass, lucinid bivalves, and their sulfide-oxidizing gill bacteria reduces sulfide stress for seagrasses. We found that the bivalve–sulfide-oxidizer symbiosis reduced sulfide levels and enhanced seagrass production as measured in biomass. In turn, the bivalves and their endosymbionts profit from organic matter accumulation and radial oxygen release from the seagrass roots. These findings elucidate the long-term success of seagrasses in warm waters and offer new prospects for seagrass ecosystem conservation.

Data from: A three-stage symbiosis forms the foundation of seagrass ecosystems

Item does not contain fulltextSeagrasses evolved from terrestrial plants into marine foundation species around 100 million years ago. Their ecological success, however, remains a mystery because natural organic matter accumulation within the beds should result in toxic sediment sulfide levels. Using a meta-analysis, a field study, and a laboratory experiment, we reveal how an ancient three-stage symbiosis between seagrass, lucinid bivalves, and their sulfide-oxidizing gill bacteria reduces sulfide stress for seagrasses. We found that the bivalve–sulfide-oxidizer symbiosis reduced sulfide levels and enhanced seagrass production as measured in biomass. In turn, the bivalves and their endosymbionts profit from organic matter accumulation and radial oxygen release from the seagrass roots. These findings elucidate the long-term success of seagrasses in warm waters and offer new prospects for seagrass ecosystem conservation

Habitat collapse due to overgrazing threatens turtle conservation in marine protected areas

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Data from: Habitat collapse due to overgrazing threatens turtle conservation in marine protected areas

Item does not contain fulltextMarine protected areas (MPAs) are key tools for combatting the global overexploitation of endangered species. The prevailing paradigm is that MPAs are beneficial in helping to restore ecosystems to more ‘natural’ conditions. However, MPAs may have unintended negative effects when increasing densities of protected species exert destructive effects on their habitat. Here, we report on severe seagrass degradation in a decade-old MPA where hyper-abundant green turtles adopted a previously undescribed below-ground foraging strategy. By digging for and consuming rhizomes and roots, turtles create abundant bare gaps, thereby enhancing erosion and reducing seagrass regrowth. A fully parametrized model reveals that the ecosystem is approaching a tipping point, where consumption overwhelms regrowth, which could potentially lead to complete collapse of the seagrass habitat. Seagrass recovery will not ensue unless turtle density is reduced to nearly zero, eliminating the MPA's value as a turtle reserve. Our results reveal an unrecognized, yet imminent threat to MPAs, as sea turtle densities are increasing at major nesting sites and the decline of seagrass habitat forces turtles to concentrate on the remaining meadows inside reserves. This emphasizes the need for policy and management approaches that consider the interactions of protected species with their habitat

Decreased costs and retained QoL due to the 'PACE Steps to Success' intervention in LTCFs: Cost-effectiveness analysis of a randomized controlled trial

Background: The number of residents in long-term care facilities (LTCFs) in need of palliative care is growing in the Western world. Therefore, it is foreseen that significantly higher percentages of budgets will be spent on palliative care. However, cost-effectiveness analyses of palliative care interventions in these settings are lacking. Therefore, the objective of this paper was to assess the cost-effectiveness of the 'PACE Steps to Success' intervention. PACE (Palliative Care for Older People) is a 1-year palliative care programme aiming at integrating general palliative care into day-to-day routines in LTCFs, throughout seven EU countries. Methods: A cluster RCT was conducted. LTCFs were randomly assigned to intervention or usual care. LTCFs reported deaths of residents, about whom questionnaires were filled in retrospectively about resource use and quality of the last month of life. A health care perspective was adopted. Direct medical costs, QALYs based on the EQ-5D-5L and costs per quality increase measured with the QOD-LTC were outcome measures. Results: Although outcomes on the EQ-5D-5L remained the same, a significant increase on the QOD-LTC (3.19 points, p value 0.00) and significant cost-savings were achieved in the intervention group (€983.28, p value 0.020). The cost reduction mainly resulted from decreased hospitalization-related costs (€919.51, p value 0.018). Conclusions: Costs decreased and QoL was retained due to the PACE Steps to Success intervention. Significant cost savings and improvement in quality of end of life (care) as measured with the QOD-LTC were achieved. A clinically relevant difference of almost 3 nights shorter hospitalizations in favour of the intervention group was found. This indicates that timely palliative care in the LTCF setting can prevent lengthy hospitalizations while retaining QoL. In line with earlier findings, we conclude that integrating general palliative care into daily routine in LTCFs can be cost-effective. Trial registration: ISRCTN14741671