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298 result(s) for "Maina, Joseph"
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Climate and land-use changes reduce the benefits of terrestrial protected areas
Expanding and enhancing protected area networks (PAs) is at the forefront of efforts to conserve and restore global biodiversity but climate change and habitat loss can interact synergistically to undermine the potential benefits of PAs. Targeting conservation, adaptation and mitigation efforts requires understanding climate and land-use patterns within PAs, both currently and under future scenarios. Here, projecting rates of temporal and spatial displacement of climate and land-use revealed that more than one-quarter of the world’s PAs (~27%) are located in regions that will experience both high rates of climate change and land-use change by 2050. Substantial changes are expected to occur more often within PAs distributed across tropical moist and grassland biomes, which currently host diverse tetrapods and vascular plants, and fall into less-stringent management categories. Taken together, our findings can inform spatially adaptive natural resource management and actions to achieve sustainable development and biodiversity goals.The authors project future rates of temporal and spatial displacement of climate and land-use in protected areas (PAs), and show that more than one-quarter of the world’s PAs are highly threatened, with particular risk to PAs across tropical moist and grassland biomes.
Highly variable taxa-specific coral bleaching responses to thermal stresses
Complex histories of chronic and acute sea surface temperature (SST) stresses are expected to trigger taxon- and location-specific responses that will ultimately lead to novel coral communities. The 2016 El Niño-Southern Oscillation provided an opportunity to examine large-scale and recent environmental histories on emerging patterns in 226 coral communities distributed across 12 countries from East Africa to Fiji. Six main coral communities were identified that largely varied across a gradient of Acropora to massive Porites dominance. Bleaching intensity was taxon-specific and was associated with complex interactions among the 20 environmental variables that we examined. Coral community structure was better aligned with the historical temperature patterns between 1985 and 2015 than the 2016 extreme temperature event. Additionally, bleaching responses observed during 2016 differed from historical reports during past warm years. Consequently, coral communities present in 2016 are likely to have been reorganized by both long-term community change and acclimation mechanisms. For example, less disturbed sites with cooler baseline temperatures, higher mean historical SST background variability, and infrequent extreme warm temperature stresses were associated with Acropora-dominated communities, while more disturbed sites with lower historical SST background variability and frequent acute warm stress were dominated by stress-resistant massive Porites corals. Overall, the combination of taxon-specific responses, community-level reorganization over time, geographic variation, and multiple environmental stressors suggest complex responses and a diversity of future coral communities that can help contextualize management priorities and activities.
Modeling Reef Fish Biomass, Recovery Potential, and Management Priorities in the Western Indian Ocean
Fish biomass is a primary driver of coral reef ecosystem services and has high sensitivity to human disturbances, particularly fishing. Estimates of fish biomass, their spatial distribution, and recovery potential are important for evaluating reef status and crucial for setting management targets. Here we modeled fish biomass estimates across all reefs of the western Indian Ocean using key variables that predicted the empirical data collected from 337 sites. These variables were used to create biomass and recovery time maps to prioritize spatially explicit conservation actions. The resultant fish biomass map showed high variability ranging from ~15 to 2900 kg/ha, primarily driven by human populations, distance to markets, and fisheries management restrictions. Lastly, we assembled data based on the age of fisheries closures and showed that biomass takes ~ 25 years to recover to typical equilibrium values of ~1200 kg/ha. The recovery times to biomass levels for sustainable fishing yields, maximum diversity, and ecosystem stability or conservation targets once fishing is suspended was modeled to estimate temporal costs of restrictions. The mean time to recovery for the whole region to the conservation target was 8.1(± 3SD) years, while recovery to sustainable fishing thresholds was between 0.5 and 4 years, but with high spatial variation. Recovery prioritization scenario models included one where local governance prioritized recovery of degraded reefs and two that prioritized minimizing recovery time, where countries either operated independently or collaborated. The regional collaboration scenario selected remote areas for conservation with uneven national responsibilities and spatial coverage, which could undermine collaboration. There is the potential to achieve sustainable fisheries within a decade by promoting these pathways according to their social-ecological suitability.
Recovery potential of the world's coral reef fishes
A study of the recovery potential of over 800 of the world's coral reefs shows that 83% of fished reefs are missing more than half their expected biomass, with severe consequences for key ecosystem functions; protection from fishing would allow full recovery in 35 years on average, but in 59 years for the most degraded reefs. Restoring overfished coral reefs Many of the world's coral reefs are overfished, prompting widespread calls for solutions to the 'coral reef crisis'. This study of the recovery potential of more than 800 coral reefs shows that 83% of fished reefs are missing more than half their expected biomass, with severe consequences for key ecosystem functions. Protection from fishing would allow full recovery in 35 years on average, but 59 years for recovery of the most degraded reefs. The authors conclude that vital ecosystem functions in degraded coral reefs can be maintained through a combination of fisheries restrictions and — in regions where marine reserves are impractical — alternative conservation strategies. Continuing degradation of coral reef ecosystems has generated substantial interest in how management can support reef resilience 1 , 2 . Fishing is the primary source of diminished reef function globally 3 , 4 , 5 , leading to widespread calls for additional marine reserves to recover fish biomass and restore key ecosystem functions 6 . Yet there are no established baselines for determining when these conservation objectives have been met or whether alternative management strategies provide similar ecosystem benefits. Here we establish empirical conservation benchmarks and fish biomass recovery timelines against which coral reefs can be assessed and managed by studying the recovery potential of more than 800 coral reefs along an exploitation gradient. We show that resident reef fish biomass in the absence of fishing ( B 0 ) averages ∼1,000 kg ha −1 , and that the vast majority (83%) of fished reefs are missing more than half their expected biomass, with severe consequences for key ecosystem functions such as predation. Given protection from fishing, reef fish biomass has the potential to recover within 35 years on average and less than 60 years when heavily depleted. Notably, alternative fisheries restrictions are largely (64%) successful at maintaining biomass above 50% of B 0 , sustaining key functions such as herbivory. Our results demonstrate that crucial ecosystem functions can be maintained through a range of fisheries restrictions, allowing coral reef managers to develop recovery plans that meet conservation and livelihood objectives in areas where marine reserves are not socially or politically feasible solutions.
Revisiting \success\ and \failure\ of marine protected areas: A conservation scientist perspective
Marine protected areas (MPAs) form the cornerstone of marine conservation. Identifying which factors contribute to their success or failure is crucial considering the international conservation targets for 2020 and the limited funds generally available for marine conservation. We identified common factors of success and/or failure of MPA effectiveness using peer-reviewed publications and first-hand expert knowledge for 27 case studies around the world. We found that stakeholder engagement was considered as the most important factor affecting MPA success, and equally, its absence, was the most important factor driving failure. Conversely, while some factors were identified as critical for success, their absence was not considered as a driver of failure, and vice versa. This mismatch provided impetus for considering these factors more critically. Bearing in mind that most MPAs have multiple objectives, including non-biological, this highlights the need for the development and adoption of standardized effectiveness metrics, besides biological considerations, to measure factors contributing to the success or failure of MPAs to reach their objectives. Considering our conclusions, we suggest the development of specific protocols for the assessment of stakeholder engagement, the role of leadership, the capacity of enforcement and compliance with MPAs objectives. Moreover, factors defining the success and failure of MPAs should be assessed not only by technical experts and the relevant authorities, but also by other stakeholder groups whose compliance is critical for the successful functioning of an MPA. Combining these factors with appropriate ecological, social, and economic data should then be incorporated into adaptive management to improve MPA
What remains to be discovered
Aim Recent unprecedented efforts to digitise and mobilise biodiversity data have resulted in the generation of ‘biodiversity big data’, enabling ecological research at scales previously not possible. However, gaps, biases and uncertainties in these data influence analytical outcomes and the validity of scientific research and conservation actions. Here, we estimated tree species inventory completeness globally and identified where future surveys should focus to maximise regional inventories. Location Global. Methods We analysed spatial patterns in sampling effort of tree species occurrence records from the Global Biodiversity and Information Facility (GBIF) and estimated global tree species inventory completeness for 100 × 100 km grid cells (sampling units) and ecoregions. We also identified forested areas for future botanical exploration, by examining the spatial overlap between inventory completeness, remaining natural habitat and protected areas and degrees of forest modification by anthropogenic pressure (forest integrity). Results Spatial patterns in sampling effort and tree species inventory completeness were unevenly distributed around the world. Only 35% of ecoregions and 18% of sampling units can be considered well surveyed, most of which were concentrated in the Global North, including Europe, North America and Australia. Large areas in species‐rich tropical regions, especially in Southeast Asia, remained poorly documented. Moreover, our results showed that many areas with low inventory completeness overlapped with ecoregions retaining less than 50% of natural habitat and protected land area, as well as sampling units with low forest integrity. Main Conclusions Due to limitations in biodiversity data, simply sampling more will not necessarily lead to increasing knowledge. We illustrated how gaps in these data can be used to improve existing knowledge by identifying priority areas for future surveys. With ongoing anthropogenic impacts and escalating rates of biodiversity loss, limited resources should be allocated to strategically survey regions likely to yield new knowledge and improve biodiversity representativeness.
Tracing the influence of land-use change on water quality and coral reefs using a Bayesian model
Coastal ecosystems can be degraded by poor water quality. Tracing the causes of poor water quality back to land-use change is necessary to target catchment management for coastal zone management. However, existing models for tracing the sources of pollution require extensive data-sets which are not available for many of the world’s coral reef regions that may have severe water quality issues. Here we develop a hierarchical Bayesian model that uses freely available satellite data to infer the connection between land-uses in catchments and water clarity in coastal oceans. We apply the model to estimate the influence of land-use change on water clarity in Fiji. We tested the model’s predictions against underwater surveys, finding that predictions of poor water quality are consistent with observations of high siltation and low coverage of sediment-sensitive coral genera. The model thus provides a means to link land-use change to declines in coastal water quality.
Temperature patterns and mechanisms influencing coral bleaching during the 2016 El Niño
Under extreme heat stress, corals expel their symbiotic algae and colour (that is, ‘bleaching’), which often leads to widespread mortality. Predicting the large-scale environmental conditions that reinforce or mitigate coral bleaching remains unresolved and limits strategic conservation actions1,2. Here we assessed coral bleaching at 226 sites and 26 environmental variables that represent different mechanisms of stress responses from East Africa to Fiji through a coordinated effort to evaluate the coral response to the 2014–2016 El Niño/Southern Oscillation thermal anomaly. We applied common time-series methods to study the temporal patterning of acute thermal stress and evaluated the effectiveness of conventional and new sea surface temperature metrics and mechanisms in predicting bleaching severity. The best models indicated the importance of peak hot temperatures, the duration of cool temperatures and temperature bimodality, which explained ~50% of the variance, compared to the common degree-heating week temperature index that explained only 9%. Our findings suggest that the threshold concept as a mechanism to explain bleaching alone was not as powerful as the multidimensional interactions of stresses, which include the duration and temporal patterning of hot and cold temperature extremes relative to average local conditions.
Walking the talk: voluntary actions on marine protected areas on the high seas
Consensus-building in multilateral sectoral organizations can be crucial to the designation of marine protected areas (MPAs) on the high seas. While the consensus procedure can be abused to block collective decisions, the obligation-alone nature of MPAs allows states to observe those MPA proposals voluntarily without undermining formal negotiations. When implemented collectively in particular scenarios, such actions can deliver cumulative conservation efforts and alter the political dynamics to complement decision-making.