Key link between iron and the size structure of three main mesoplanktonic groups (Crustaceans, Rhizarians, and colonial N2-fixers) in the Upper Ocean Article Swipe
YOU?
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· 2024
· Open Access
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· DOI: https://doi.org/10.1101/2024.03.08.584097
· OA: W4392776691
In marine ecosystems, critical services like fish production, carbon export, or the delivery of nutrients through N 2 -fixation rely heavily on the size spectrum of pelagic organisms, particularly mesoplankton (200-20,000 µm). However, how environmental factors shape mesoplankton spectral biogeography remains largely unresolved, as so far only limited datasets exist to understand the large-scale shifts in mesoplankton size. Using global compilations of Rhizarian, colonial N 2 -fixer, and Crustacean images, we reveal the paramount role of iron in shaping the size structure and related biogeography of these groups. Our findings underscore the importance of atmospheric sources of iron for N 2 -fixers and Rhizarians while total iron, accounting for organic and inorganic compounds, appeared to explain most of the variance in Crustacean size structure via apparent recycling. With a comprehensive set of explanatory variables, our models reached high R 2 (0.93, 0.61, and 0.69 respectively), providing robust predictions of mesoplankton size structure related to elemental cycling and ecosystem services. Our results suggest that future increases in global temperatures will have negative effects on mesoplankton size, possibly limiting carbon export from the productive layers to sequestration depth, that can be offset by expected increases in iron inputs that benefit N 2 -fixers, Rhizarians, and eventually Crustaceans.
