Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Related Publications
• Parameters
• Instruments
• Project Information
• Funding

General study design:
Coral communities with different benthic cover (0, 40, 80%) were created in flow-through mesocosms exposed to natural environmental variations. The experiment was designed to examine how benthic metabolism influence diurnal seawater carbonate chemistry and how this scales with varying coral cover. The experiment was conducted at the Coral Reef Ecology Laboratory at the Hawaii Institute of Marine Biology in Kaneohe, HI, USA.

Methods description:
Coral communities with planar surface area coverage ranging 0, 20, 40, 60, 80 and 100 percent were created within flow-through mesocosms. Diurnal seawater chemistry was measured for communities during June 2016 by taking hourly water measurements (T, S, DO_sat, DO_conc, and pH) and collecting water samples for dissolved inorganic carbon (DIC) and total alkalinity (TA) every 3 hours over 24-hour time periods. Seawater chemistry data were used to calculate diurnal net community production (NCP) and net community calcification (NCC) rates using modified standard equations (Langdon et al. 2010).

Analytical Methods:
Seawater samples were collected by hand using 250 ml Pyrex glass bottles and fixed with 100 µL HgCl2 as per standard protocols (Dickson et al. 2007). Handheld YSI multi-meter instrument was used to measure temperature, salinity, dissolved oxygen, and pH at the time of sampling. All seawater samples were transported to the Scripps Coastal and Open Ocean Biogeochemistry lab and analyzed for TA via an open-cell potentiometric acid titration system developed at Scripps Institution of Oceanography (SIO) by A. Dickson (Dickson et al. 2007) and DIC via an automated infra-red inorganic carbon analyzer (AIRICA, Marianda Inc).

Quality Control:
Standard protocols were followed for sampling and analysis of seawater TA and DIC (Dickson et al. 2007). YSI multi-meter instrument was calibrated prior to each sampling period with accuracies of 0.2 °C for temperature, 1% for salinity, ±2% for dissolved oxygen saturation, 0.2 mg/L for dissolved oxygen concentration, and 0.2 for pH. The accuracy and precision of TA (0.33 ± 2.21 μmol/kg) and DIC (-1.31 ± 2.98 μmol/kg) measurements were evaluated using certified reference materials (CRM) provided by the laboratory of A. Dickson at SIO and analyzed every 5 samples for DIC and ~15-20 samples for TA.

For additional information please see Page et al. (2017).

Known Problems:
Rows for Mesocosm_IDs of "Header 1"," 9", and "10" on Date 14-06-16 and Time 00:00 (lines 56, 60, 62 in original Excel file): TA did not pass QAQC and therefore were omitted. Consequently, NCC and NCP could not be calculated for these data.

Data Processing:
Carbonate chemistry (pH_calc, pCO2_calc, and omega_calc) was constrained using CO2SYS software (Lewis and Wallace 1998). Data were processed and statistically compared using R Software (v 3.2.0).

BCO-DMO Processing:
- added UTC date/time field in ISO8601 format.

NSF Award Abstract:
Because of well-known chemical principles, changes in the CO2 chemistry of seawater in the open ocean as a result of rising atmospheric CO2 can be predicted very accurately. On the other hand, in near-shore environments, these projections are much more difficult because the CO2 chemistry is largely modified by biogeochemical processes operating on timescales of hours to months. To make predictions on how near-shore seawater CO2 chemistry will change in response to ocean acidification (OA), it is critical to consider the relative influence of net ecosystem production (NEP) and net ecosystem calcification (NEC), and how these processes might change in response to this major perturbation. Understanding how future OA will alter near-shore seawater CO2 chemistry and variability was identified as a major critical knowledge gap at the recent IPCC WG II/WG I workshop on impacts of ocean acidification on marine biology and ecosystems in January of 2011, and also at the International Ocean Acidification Network workshop in Seattle in June of 2012.

With funding from this CAREER award, a researcher at the Scripps Institute of Oceanography and his students will study how biogeochemical processes and the relative contributions from NEP and NEC modify seawater CO2 chemistry in near-shore environments influenced by different benthic communities under well-characterized environmental and physical conditions, and how these processes might change in response to OA. The team will investigate a limited number of contrasting habitats in subtropical (reef crest, back/patch reef, lagoon, seagrass bed, algal mat) and temperate (kelp bed, inter- and sub-tidal, marsh) environments during summer and winter, employing a method that evaluates the function and performance of the carbon cycle of a system using a stoichiometric vector approach based on changes in total dissolved inorganic carbon (DIC) and total alkalinity (TA). These field studies will be complemented by controlled mesocosm experiments with contrasting and mixed benthic communities under different OA scenarios.

The project has two educational components: (1) developing a research-driven OA and biogeochemistry course based on inquiry-, experience-, and collaborative-based learning; and (2) working with the Ocean Discovery Institute (ODI) to engage individuals from a local underrepresented minority community in science through educational activities focused on OA, and also providing a moderate number of internships for high school and college students to engage in this research project.

Broader Impacts: This project will directly support one PhD student, one junior research technician, and two high school and college interns from underrepresented minorities (URM) each summer of the project. It will contribute to the education of 80 undergraduate and graduate students participating in the research based ocean acidification/biogeochemistry course offered four times throughout the duration of the project at SIO/UCSD. Education and curricular material on the topics of OA, including hands-on laboratories, classroom and field-based activities will be developed through the collaboration with the ODI and brought to hundreds of URM students and their teachers in the City Heights area, a community with the highest poverty and ethnic diversity in the San Diego region. This collaboration will enable URM students to directly engage in a rapidly evolving field of research that has high relevance at both the local and global scales. To ensure broad dissemination of this project and the topic of OA, the research team will work with the Google Ocean team to incorporate information and educational material in the Google Ocean Explorer.