High-Frequency Dynamics of Ocean pH: A Multi-Ecosystem Comparison

Abstract

The effect of Ocean Acidification (OA) on marine biota is quasi-predictable at best. While perturbation studies, in the form of incubations under elevated pCO ₂, reveal sensitivities and responses of individual species, one missing link in the OA story results from a chronic lack of pH data specific to a given species' natural habitat. Here, we present a compilation of continuous, high-resolution time series of upper ocean pH, collected using autonomous sensors, over a variety of ecosystems ranging from polar to tropical, open-ocean to coastal, kelp forest to coral reef. These observations reveal a continuum of month-long pH variability with standard deviations from 0.004 to 0.277 and ranges spanning 0.024 to 1.430 pH units. The nature of the observed variability was also highly site-dependent, with characteristic diel, semi-diurnal, and stochastic patterns of varying amplitudes. These biome-specific pH signatures disclose current levels of exposure to both high and low dissolved CO ₂, often demonstrating that resident organisms are already experiencing pH regimes that are not predicted until 2100. Our data provide a first step toward crystallizing the biophysical link between environmental history of pH exposure and physiological resilience of marine organisms to fluctuations in seawater CO ₂. Knowledge of this spatial and temporal variation in seawater chemistry allows us to improve the design of OA experiments: we can test organisms with a priori expectations of their tolerance guardrails, based on their natural range of exposure. Such hypothesis-testing will provide a deeper understanding of the effects of OA. Both intuitively simple to understand and powerfully informative, these and similar comparative time series can help guide management efforts to identify areas of marine habitat that can serve as refugia to acidification as well as areas that are particularly vulnerable to future ocean change.

Affiliations

[1 ]Department of Ecology, Evolution and Marine Biology, University of California Santa Barbara, Santa Barbara California, United States of America

[2 ]Scripps Institution of Oceanography, University of California San Diego, La Jolla, California, United States of America

[3 ]Monterey Bay Aquarium Research Institute, Moss Landing, California, United States of America

[4 ]Department of Biology, Stanford University, Hopkins Marine Station, Pacific Grove, California, United States of America

[5 ]Institute of Marine Sciences, University of California Santa Cruz, Santa Cruz, California, United States of America

[6 ]Laboratory of Functional and Evolutionary Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy

University of California Merced, United States of America

Author notes

* E-mail: trmartz@ 123456ucsd.edu

Conceived and designed the experiments: GEH TRM JES KSJ US LAL FM AP. Performed the experiments: BP YT JES US AP NNP PGM EDC KJK MCG EBR CAF PCY. Analyzed the data: GEH JES KSJ US LAL FM AP NNP PGM EDC KJK EBR CAF PCY TRM. Wrote the paper: GEH TRM.

Contributors

Wei-Chun Chin: Role: Editor

Journal

Journal ID (nlm-ta): PLoS One

Journal ID (publisher-id): plos

Journal ID (pmc): plosone

Title: PLoS ONE

Publisher: Public Library of Science (San Francisco, USA )

ISSN (Electronic): 1932-6203

Publication date Collection 2011

Publication date (Electronic): 19 December 2011

Volume: 6

Issue: 12

PMC ID: 3242773

PubMed ID: 22205986

Publisher ID: PONE-D-11-19773

DOI: 10.1371/journal.pone.0028983

Other contributors: Wei-Chun Chin (Editor)

Copyright statement: Hofmann et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

Counts

Pages: 11

Categories

Subject: Research Article

Subject: Biology

Subject: Ecology

Subject: Marine Ecology

Subject: Marine Biology

Subject: Marine Ecology

Subject: Marine Monitoring

Subject: Marine Technology

Subject: Earth Sciences

Subject: Marine and Aquatic Sciences

Subject: Oceanography

Subject: Chemical Oceanography

Subject: Ocean Properties

Subject: Marine Biology

Subject: Marine Ecology