Ocean temperature drove changes in the mesopelagic fish community at the edge of the Pacific Warm Pool over the past 460,000 years

Abstract

Field observations and theoretical modeling suggest that ongoing anthropogenic ocean warming will lead to marine ecosystem degradation. Mesopelagic fish are a fundamental component of the pelagic ecosystem, and their role in linking the surface- and deep-ocean ecosystems is essential for the biological carbon pump. However, their response to a warmer ocean is unconstrained because of data scarcity. Using extraordinarily well-preserved fish otoliths, we reconstruct a continuous mesopelagic fish community record in the Pacific Warm Pool region over 460,000 years. Fish production and diversity followed hump-shaped temperature gradients, with lower tipping point temperatures for the diversity than the production by ~1.5° to 2.0°C. During warmer-than-present interglacial periods, both production and diversity declined drastically. Our findings imply that the temperature-sensitive mesopelagic fish community at the southwestern margin of the Pacific Warm Pool, and possibly other hydrographically similar regions, may be especially affected if ocean warming continues unabated in the future.

Deep‐pelagic fishes: Demographic instability in a stable environment

“…Lin et al. 2023 ) utilized fossilized otoliths to investigate trends in deep‐pelagic fishes in the Warm Pacific Pool over the last 460 thousand years (Lin et al., 2023 ). They included species from five major deep‐pelagic families and found temporal changes in the number of otoliths present in the fossil record as well as the community composition.…”

“…The deep‐benthic environment, benthic habitat found below 200 m depth, is much more heterogeneous than the deep‐pelagic and likely under differing environmental pressures (Sutton et al., 2017 ; Thurber et al., 2014 ; Watling et al., 2013 ). Recent publications based on the fossil record have reported local changes in deep‐pelagic fish abundance and community composition (Lin et al., 2023 ; Salvatteci et al., 2022 ). These observations could be indicative of range changes and fluctuations in population size.…”

“…identified fossilized vertebrae to compare the community structure of fishes inhabiting Humboldt Current at two points in time (the last interglacial and the Holocene)(Salvatteci et al, 2022). The study includes two deep-pelagic species, with one species increasing and the other decreasing in frequency in the Holocene sample Lin et al 2023(Lin et al, 2023).…”

“…The study includes two deep-pelagic species, with one species increasing and the other decreasing in frequency in the Holocene sample Lin et al 2023(Lin et al, 2023). They included species from five major deep-pelagic families and found temporal changes in the number of otoliths present in the fossil record as well as the community composition.…”