Including high frequency variability in coastal ocean acidification projections

Abstract

Abstract. Assessing the impacts of anthropogenic ocean acidification requires knowledge of present-day and future environmental conditions. Here, we present a simple model for upwelling margins that projects anthropogenic acidification trajectories by combining high-temporal resolution sensor data, hydrographic surveys for source water characterization, empirical relationships of the CO2 system, and the atmospheric CO2 record. This model characterizes CO2 variability on timescales ranging from hours (e.g. tidal) to months (e.g. seasonal), bridging a critical knowledge gap in ocean acidification research. The amount of anthropogenic carbon in a given water mass is dependent on the age, therefore a density–age relationship was derived for the study region, and was combined with the 2013 Intergovernmental Panel on Climate Change CO2 emission scenarios to add density-dependent anthropogenic carbon to the sensor time series. The model was applied to time series from four autonomous pH sensors, each deployed in the surf zone, kelp forest, submarine canyon edge, and shelf break in the upper 100 m of the Southern California Bight. All habitats were within 5 km of one another, and exhibited unique, habitat-specific CO2 variability signatures and acidification trajectories, demonstrating the importance of making projections in the context of habitat-specific CO2 signatures. In general, both the mean and range of pCO2 increase in the future, with the greatest increases in both magnitude and range occurring in the deeper habitats due to reduced buffering capacity. On the other hand, the saturation state of aragonite (ΩAr) decreased in both magnitude and range. This approach can be applied to the entire California Current System, and upwelling margins in general, where sensor and complementary hydrographic data are available.

Measuring pH in the Arctic Ocean: Colorimetric method or SeaFET?

“…The high resolution of the dataset allowed the investigators to demonstrate that local advection pre-determines the horizontal distribution of the carbonate system whereas biological activity enhances its high variability within water masses. Automated shipboard and in situ sensors are therefore essential to obtain continuous data with high spatial and temporal resolution in order to resolve natural variations of the carbonate system and underlying changes due to anthropogenic activities (Takeshita et al, 2015).…”

Evaluating the promise and pitfalls of a potential climate change–tolerant sea urchin fishery in southern California

“…These urchins experience a range of pH and oxygen conditions depending on depth and setting (Takeshita et al , 2015; Chan et al , 2017), with the red ( M. franciscanus ) and purple ( Strongylocentrotus purpuratus ) urchins generally occupying the intertidal and inner shelf reefs (Kato and Schroeter, 1985; Rogers-Bennett, 2007), and pink urchins ( S. fragilis ) occurring throughout the outer shelf and upper slope (Sato et al , 2017; Thompson et al , 1993). Deep-sea fishery species (taken on the continental slope and seamounts) are conventionally thought to be non-sustainable due to long life spans, slow growth rates, and late maturity (Koslow et al , 2000; Norse et al , 2012).…”

Development of Embryonic Market Squid, Doryteuthis opalescens, under Chronic Exposure to Low Environmental pH and [O2]

“…The surface water [O 2 ] of the ocean is expected to decline by 1% to 7% globally in over the next century [2] and hypoxic oxygen isopleths have already shoaled by as much as 90 m over the last 25 years in the Southern California Bight with oxygen declines accelerated at inshore regions [3–6]. In addition, the surface water pH of the California Current System has declined by 0.1 units since the start of the industrial revolution [7, 8]. These conditions are of particular concern for commercially valuable species that attach eggs to the sea floor, such as the market squid Doryteuthis opalescens .…”

“…By 2060, pH is expected to decrease by 0.11–0.13 units at the 30-m embryo habitat of D . opalescens within the Southern California Bight [8]. As D .…”