article
; community
; ecology
; ecosystem
; eutrophication
; habitat
; mesocosm
; nonhuman
; nutrient loading
; otter
; predator
; priority journal
; seagrass
; time series analysis
; trophic cascade
; estuary
; eutrophication
; food web
; resilience
; Analysis of Variance
; Animals
; Brachyura
; California
; Estuaries
; Eutrophication
; Food Chain
; History, 20th Century
; History, 21st Century
; Nitrates
; Otters
; Population Dynamics
; Zosteraceae
英文摘要:
A fundamental goal of the study of ecology is to determine the drivers of habitat-forming vegetation, with much emphasis given to the relative importance to vegetation of "bottom-up" forces such as the role of nutrients and "top-down" forces such as the influence of herbivores and their predators. For coastal vegetation (e.g., kelp, seagrass, marsh, and mangroves) it has been well demonstrated that alterations to bottom-up forcing can cause major disturbances leading to loss of dominant vegetation. One such process is anthropogenic nutrient loading, which can lead to major changes in the abundance and species composition of primary producers, ultimately affecting important ecosystem services. In contrast, much less is known about the relative importance of apex predators on coastal vegetated ecosystems because most top predator populations have been depleted or lost completely. Here we provide evidence that an unusual four-level trophic cascade applies in one such system, whereby a top predator mitigates the bottom-up influences of nutrient loading. In a study of seagrass beds in an estuarine ecosystem exposed to extreme nutrient loading, we use a combination of a 50-y time series analysis, spatial comparisons, and mesocosm and field experiments to demonstrate that sea otters (Enhydra lutris) promote the growth and expansion of eelgrass (Zostera marina) through a trophic cascade, counteracting the negative effects of agriculturally induced nutrient loading. Our results add to a small but growing body of literature illustrating that significant interactions between bottom-up and top-down forces occur, in this case with consequences for the conservation of valued ecosystem services provided by seagrass.
Hughes, B.B., Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California, Santa Cruz, CA 95060, United States; Eby, R., Elkhorn Slough National Estuarine Research Reserve, Watsonville, CA 95076, United States; Van Dyke, E., Elkhorn Slough National Estuarine Research Reserve, Watsonville, CA 95076, United States; Tinker, M.T., Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California, Santa Cruz, CA 95060, United States, US Geological Survey, Western Ecological Research Center, Santa Cruz, CA 95060, United States; Marks, C.I., Seafloor Mapping Lab, Division of Science and Environmental Policy, California State University, Monterey Bay, Seaside, CA 93955, United States; Johnson, K.S., Monterey Bay Aquarium Research Institute, Moss Landing, CA 95039, United States; Wasson, K., Department of Ecology and Evolutionary Biology, Long Marine Laboratory, University of California, Santa Cruz, CA 95060, United States, Elkhorn Slough National Estuarine Research Reserve, Watsonville, CA 95076, United States
Recommended Citation:
Hughes B.B.,Eby R.,Van Dyke E.,et al. Recovery of a top predator mediates negative eutrophic effects on seagrass[J]. Proceedings of the National Academy of Sciences of the United States of America,2013-01-01,110(38)