An official website of the United States government
Abstract Effective management of wild animals requires understanding how predation and harvest alter the composition of populations. These top‐down processes can alter consumer body size and behavior and thus should also have consequences for bottom‐up processes because (1) body size is a critical determinant of the amount of nutrients excreted and (2) variation in foraging behavior, which is strongly influenced by predation, can determine the amount and spatial distribution of nutrients. Changes to either are known to affect ecosystem‐scale nutrient dynamics, but the consequences of these dynamics on ecosystem processes are poorly understood. We used an individual‐based model of an artificial reef (AR) and reef fish in a subtropical seagrass bed to test how fish body size can interact with variation in foraging behavior at the population and individual levels to affect seagrass production in a nutrient‐limited system. Seagrass production dynamics can be driven by both belowground (BGPP) and aboveground primary production (AGPP); thus, we quantified ecosystem‐scale production via these different mechanistic pathways. We found that (1) populations of small fish generated greater total primary production (TLPP = BGPP + AGPP) than large fish, (2) fish that foraged more increased TLPP more than those that spent time sheltering on ARs, and (3) small fish that foraged more led to greatest increases in TLPP. The mechanism by which this occurred was primarily through increased BGPP, highlighting the importance of cryptic belowground dynamics in seagrass ecosystems. Populations of extremely bold individuals (i.e., foraged significantly more) slightly increased TLPP but strongly affected the distribution of production, whereby bold individuals increased BGPP, while populations of shy individuals increased AGPP. Taken together, these results provide a link between consumer body size, variation in consumer behavior, and primary production—which, in turn, will support secondary production for fisheries. Our study suggests that human‐induced changes—such as fishing—that alter consumer body size and behavior will fundamentally change ecosystem‐scale production dynamics. Understanding the ecosystem effects of harvest on consumer populations is critical for ecosystem‐based management, including the development of ARs for fisheries.
more »
« less
This content will become publicly available on February 14, 2026
Elephant seals as ecosystem sentinels for the northeast Pacific Ocean twilight zone
The open ocean twilight zone holds most of the global fish biomass but is poorly understood owing to difficulties of measuring subsurface ecosystem processes at scale. We demonstrate that a wide-ranging carnivore—the northern elephant seal—can serve as an ecosystem sentinel for the twilight zone. We link ocean basin–scale foraging success with oceanographic indices to estimate twilight zone fish abundance five decades into the past, and into the future. We discovered that a small variation in maternal foraging success amplified into larger changes in offspring body mass and enormous variation in first-year survival and recruitment. Worsening oceanographic conditions could shift predator population trajectories from current growth to sharp declines. As ocean integrators, wide-ranging predators could reveal impacts of future anthropogenic change on open ocean ecosystems.
more »
« less
- PAR ID:
- 10610246
- Author(s) / Creator(s):
- ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more »
- Publisher / Repository:
- Science
- Date Published:
- Journal Name:
- Science
- Volume:
- 387
- Issue:
- 6735
- ISSN:
- 0036-8075
- Page Range / eLocation ID:
- 764 to 769
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Paleontological reconstructions of plankton community structure during warm periods of the Cenozoic (last 66 million years) reveal that deep-dwelling ‘twilight zone’ (200–1000 m) plankton were less abundant and diverse, and lived much closer to the surface, than in colder, more recent climates. We suggest that this is a consequence of temperature’s role in controlling the rate that sinking organic matter is broken down and metabolized by bacteria, a process that occurs faster at warmer temperatures. In a warmer ocean, a smaller fraction of organic matter reaches the ocean interior, affecting food supply and dissolved oxygen availability at depth. Using an Earth system model that has been evaluated against paleo observations, we illustrate how anthropogenic warming may impact future carbon cycling and twilight zone ecology. Our findings suggest that significant changes are already underway, and without strong emissions mitigation, widespread ecological disruption in the twilight zone is likely by 2100, with effects spanning millennia thereafter.more » « less
-
Abstract The strength of the biological soft tissue pump in the ocean critically depends on how much organic carbon is produced via photosynthesis and how efficiently the carbon is transferred to the ocean interior. For a given amount of limiting nutrient, phosphate, soft tissue pump would be strengthened if the carbon (C) to phosphorus (P) ratio of sinking organic matter increases as the remineralization length scale of C increases. Here, we present a new data compilation of particle flux stoichiometry and show that C:P of sinking particulate organic matter (POM) in the ocean twilight zone on average is likely to be higher than the C:P ratio of surface suspended POM. We further demonstrate using a physics‐biology coupled global ocean model combined with a theory from first principles that an increase in C:P export flux ratio in the ocean's twilight zone can lead to a considerable drawdown of atmosphericpCO2.more » « less
-
Historically, oceanographic time-series have focused on long-term measurements of large open ocean gyres; yet, the coastal oceans, with their high productivity, tidal impacts, human feedbacks, and land-sea coupling, represent critical regions for predicting ocean dynamics and biogeochemistry under global change. The Piver’s Island Coastal Observatory (PICO) time-series, located in the second largest estuarine system on the US East Coast (Albemarle-Pamlico Sound), comprises more than a decade of weekly (or more frequent) measurements of core physical, chemical, and biological oceanographic variables. PICO provides insight into a coastal, mesotrophic ecosystem in an ecologically-diverse and biochemically-active region impacted by global change. Here, we report on a decade of observations focusing on pulse and press ecosystem changes. We observe strong mean annual cycles in environmental variables including temperature (10.1-28.9°C), pH (7.89-8.12), dissolved inorganic carbon (DIC: 1965 – 2088 µM), chlorophyll (2.54-5.77 mg Chl m-3), upon which are layered episodic disturbances (e.g., tropical cyclones) that dramatically and persistently (>1 month) impact this ecosystem. Among other variables, long term trends in pH (-0.004 ± 0.001 y-1; p<0.01), DIC (-9.8 ± 1.5 µM y-1; p<0.01) and chlorophyll (-0.17 ± 0.02 µg L-1y-1; p<0.01) are exceeding those observed in the open ocean, suggesting an ecosystem in flux. These analyses provide a benchmark for future studies of the impact of changing climate and oceanographic climatology; further research will use this long-term research to developed targeted sampling and experimental manipulations to better understand ecosystem structure and function.more » « less
-
Abstract The Tara Oceans program has delivered major advances in our knowledge of ocean plankton diversity and complexity, shedding light on key interactions that explain their success on a planetary scale. In this issue, Caputi et al. (2019,https://doi.org/10.1029/2018GB006022) further contribute to this knowledge through combining comprehensive bio‐oceanographic genomic and transcriptomic Tara Oceans data sets with iron distributions derived from two global‐scale biogeochemical models. Their findings reveal the prevalence of iron as a limiting nutrient in pelagic ecosystems at both local and global scales, exerting a considerable force that drives plankton evolution and shapes community structure. Integration of omics data (i.e., genomics, transcriptomics, proteomics, and metabolomics) with oceanographic properties and biogeochemical models will transform our view of the ocean ecosystem and its role on a changing planet.more » « less
