March 2025 science summary

Greetings,

Work has been pretty hectic so I've been reading less public science papers lately but have two good ones to share on "old and wise animals" and freshwater prioritization.

Like many others, I've also been struggling with the chaos and hurtful policy and people suffering from the recent political changes in the US.

I don't have answers, but have been finding that connection, community, being vulnerable, and supporting each other is helpful. As is finding joy wherever we can. In that spirit, here's a video of a song my chorus sang last December where I had a solo - I find it painful to watch all the mistakes but it was a joy to sing in the real world, and hope it may distract a few of you from everything going on in the world for a moment or two.

I've also found this document of things to say and not say to someone grieving can still be helpful in comforting people going through other tough situations. The main point is to resist the impulse to cheer them up and instead validate their feelings and be willing to just sit with the discomfort.

If you know someone who wants to sign up to receive these summaries, they can do so at http://bit.ly/sciencejon (no need to email me).


WILDLIFE:
Kopf et al 2024 really made me think. They summarize some of the important contributions of old (and often "wise"!) animals, and proposes "longevity conservation" as a strategy to retain them. Old animals are especially important for species who rely on cultural transmission (like migratory species) and those who reproduce more as they age and grow, and the article goes into detail with examples of both. The article also covers some of the impacts of losing large and old animals, like changing ecosystem structure and function, pack instability, and even infanticide. The ability of older animals to help their group adapt to drought or food shortages maybe increasingly important as climate changes (although the individual resilience of older animals is likely to lower to some stresses like disease). With trophy hunting and fishing selecting for larger (typically older) animals, they argue for the importance of better population modeling, setting age class targets for fisheries, restricting hunting of larger and older animals, and going beyond tracking biomass or abundance to watch for "longevity depletion."


FRESHWATER:
Sayer et al. 2025's headline is that 1/4 of freshwater animals are threatened with extinction. But that's similar to other estimates; to me the new thing here is guidance on how to prioritize sites to conserve with limited data. They found that 1) prioritizing with just threatened freshwater tetrapod data (animals with four legs like some amphibians, reptiles, birds, and mammals) does well for overall freshwater biodiversity (range-size rarity) but 2) prioritizing on abiotic factors alone (low flow / water stress, nitrogen as a proxy for water pollution) does worse than random! Also from Fig 2b permanent rivers are home to almost all of the threatened FW species, while species in other fresh wetlands fare much better.


REFERENCES:
Kopf, R. K., Banks, S., Brent, L. J. N., Humphries, P., Jolly, C. J., Lee, P. C., Luiz, O. J., Nimmo, D., & Winemiller, K. O. (2024). Loss of Earth’s old, wise, and large animals. Science, 2705, 1–19. https://doi.org/10.1126/science.ado2705

Sayer, C. A., Fernando, E., Jimenez, R. R., Macfarlane, N. B. W., Rapacciuolo, G., Böhm, M., Brooks, T. M., Contreras-MacBeath, T., Cox, N. A., Harrison, I., Hoffmann, M., Jenkins, R., Smith, K. G., Vié, J.-C., Abbott, J. C., Allen, D. J., Allen, G. R., Barrios, V., Boudot, J.-P., … Darwall, W. R. T. (2025). One-quarter of freshwater fauna threatened with extinction. Nature, 3(December 2023). https://doi.org/10.1038/s41586-024-08375-z


Sincerely,
 
Jon
 
p.s. This is a photo of a whitewater rafting trip in Chile w/ colleagues. It was beautiful and a great time albeit painful as my knee is still healing (hence the grimace)!