Marine protected areas promote stability of reef fish communities under climate warming.

Protection from direct human impacts can safeguard marine life, yet ocean warming crosses marine protected area boundaries. Here, we test whether protection offers resilience to marine heatwaves from local to network scales. We examine 71,269 timeseries of population abundances for 2269 reef fish species surveyed in 357 protected versus 747 open sites worldwide. We quantify the stability of reef fish abundance from populations to metacommunities, considering responses of species and functional diversity including thermal affinity of different trophic groups. Overall, protection mitigates adverse effects of marine heatwaves on fish abundance, community stability, asynchronous fluctuations and functional richness. We find that local stability is positively related to distance from centers of high human density only in protected areas. We provide evidence that networks of protected areas have persistent reef fish communities in warming oceans by maintaining large populations and promoting stability at different levels of biological organization.

Characterisation of aluminium black dross before and after stepwise salt-phase dissolution in non-aqueous solvents.

Aqueous leaching to recover salts from black dross is accompanied by hazardous gas generation. The gas-generating phases vary significantly across differently sourced black dross. The challenge for the industry is how to accurately qualify and quantify the problematic components of black dross, especially minor reactive phases. This paper employed XRF, EDX, XRD, Raman and FTIR to analyse two industrial black dross samples from various sources. A novel pre-treatment method before characterisation was devised using water-free glycerol and anhydrous ethanol to remove the major salt components, without reacting the gas-generating phases. The results show that around 80 % of the salts existent in the black dross had been removed successfully through pre-treatment. This method facilitated the determination of minor reactive phases characterised by XRD, XRF and EDX, and had little effect on the characterisation by Raman and FTIR spectroscopy. The ammonia-generating nitride phase was detected by XRD, Raman and FTIR. The FTIR, moreover, allowed the successful identification of carbide. Best practice guidelines for the industrial analysis of black dross has been proposed. The guidelines would provide industry with evidence to include or adjust gas treatment methods and operational parameters when dealing with compositional variability in industrially-sourced black dross.

High and distinct range-edge genetic diversity despite local bottlenecks.

The genetic consequences of living on the edge of distributional ranges have been the subject of a largely unresolved debate. Populations occurring along persistent low latitude ranges (rear-edge) are expected to retain high and unique genetic diversity. In contrast, currently less favourable environmental conditions limiting population size at such range-edges may have caused genetic erosion that prevails over past historical effects, with potential consequences on reducing future adaptive capacity. The present study provides an empirical test of whether population declines towards a peripheral range might be reflected on decreasing diversity and increasing population isolation and differentiation. We compare population genetic differentiation and diversity with trends in abundance along a latitudinal gradient towards the peripheral distribution range of Saccorhiza polyschides, a large brown seaweed that is the main structural species of kelp forests in SW Europe. Signatures of recent bottleneck events were also evaluated to determine whether the recently recorded distributional shifts had a negative influence on effective population size. Our findings show decreasing population density and increasing spatial fragmentation and local extinctions towards the southern edge. Genetic data revealed two well supported groups with a central contact zone. As predicted, higher differentiation and signs of bottlenecks were found at the southern edge region. However, a decrease in genetic diversity associated with this pattern was not verified. Surprisingly, genetic diversity increased towards the edge despite bottlenecks and much lower densities, suggesting that extinctions and recolonizations have not strongly reduced diversity or that diversity might have been even higher there in the past, a process of shifting genetic baselines.