The diversity of animals identified as keystone species

Managing and mitigating future public health risks: Planetary boundaries, global catastrophic risk, and inclusive wealth

There are two separate conceptualizations for assessing existential risks: Planetary Boundaries (PBs) and global catastrophic risks (GCRs). While these concepts are similar in principle, their underpinning literatures tend not to engage with each other. Research related to these concepts has tended to be siloed in terms of the study of specific threats and also in terms of how these are assumed to materialize; PBs attribute global catastrophes to slow-moving and potentially irreversible global changes, while GCRs focuses on cataclysmic short-term events. We argue that there is a need for a more unified approach to managing global long-term risks, which recognizes the complex and confounded nature of the interactions between PBs and GCRs. We highlight where the PB and GCR concepts overlap and outline these complexities using an example of public health, namely, pandemics and food insecurity. We also present an existing indicator that we argue can be used for monitoring and managing risk. We argue for greater emphasis on national and global ''inclusive wealth'' as a way to measure economic activity and thus to monitor and mitigate the unintended consequences of economic activity. In sum, we call for a holistic approach to stewardship aimed at preserving the integrity of natural capital in the face of a broad range of global risks and their respective regional or global manifestations.

Artificial light at night bans Chaoborus from vital epilimnetic waters

Artificial light at night (ALAN) is known to affect organisms in terrestrial ecosystems and adjacent litoral habitats. In the present study, we tested the effect of ALAN on the spatial distribution of organisms in open waters, using the insect larvae of Chaoborus flavicans as an example. During the day C. flavicans typically hide from visually hunting fish in deep, dark, anoxic waters. On safer nights, they forage in rich subsurface waters. Nighttime field tests revealed that light from an HPS street lamp mounted on a boat anchored in open water attracted planktivorous fish, but deterred planktonic Chaoborus from rich but risky surface waters. Chaoborus did not descend to the safest, anoxic hypolimnion, but remained in hypoxic mid-depth metalimnion, which does not appear to be a perfect refuge. Neither light gradient nor food distribution fully explained their mid-depth residence under ALAN conditions. A further laboratory test revealed a limited tolerance of C. flavicans to anoxia. Half of the test larvae died after 38 h at 9 °C in anoxic conditions. The trade-off between predation risk and oxygen demand may explain why Chaoborus did not hide in deep anoxic waters, but remained in the riskier metalimnion with residual oxygen under ALAN conditions.

A big-headed problem drives an ecological chain reaction

Disruption of key species interactions reverberates across an African savanna.