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  • 1
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    In:  Supplement to: DeCarlo, Thomas M; Cohen, Anne L; Wong, George T F; Shiah, Fuh Kwo; Lentz, S J; Davis, Kristen A; Shamberger, K E F; Lohmann, Pat (2017): Community production modulates coral reef pH and the sensitivity of ecosystem calcification to ocean acidification. Journal of Geophysical Research: Oceans, 122, 745–761, https://doi.org/10.1002/2016JC012326
    Publication Date: 2024-03-15
    Description: Coral reefs are built of calcium carbonate (CaCO3) produced biogenically by a diversity of calcifying plants, animals and microbes. As the ocean warms and acidifies, there is mounting concern that declining calcification rates could shift coral reef CaCO3 budgets from net accretion to net dissolution. We quantified net ecosystem calcification (NEC) and production (NEP) on Dongsha Atoll, northern South China Sea, over a two-week period that included a transient bleaching event. Peak daytime pH on the wide, shallow reef flat during the non-bleaching period was 8.5, significantly elevated above that of the surrounding open ocean (8.0-8.1) as a consequence of daytime NEP (up to 112 mmol C/m**2/h). Diurnal-averaged NEC was 390?+/-?90 mmol CaCO3/m**2/day, higher than any other coral reef studied to date despite comparable calcifier cover (25%) and relatively high fleshy algal cover (19%). Coral bleaching linked to elevated temperatures significantly reduced daytime NEP by 29 mmol C/m**2/h. pH on the reef flat declined by 0.2 units, causing a 40% reduction in NEC in the absence of pH changes in the surrounding open ocean. Our findings highlight the interactive relationship between carbonate chemistry of coral reef ecosystems and ecosystem production and calcification rates, which are in turn impacted by ocean warming. As open-ocean waters bathing coral reefs warm and acidify over the 21st century, the health and composition of reef benthic communities will play a major role in determining on-reef conditions that will in turn dictate the ecosystem response to climate change.
    Keywords: Alkalinity, total; Aragonite saturation state; Benthos; Bicarbonate ion; Calcification/Dissolution; Calcification rate, standard deviation; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbon, net production; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Carbon dioxide, air-sea, flux; Coast and continental shelf; Density; DEPTH, water; Dongsha_Atoll; Entire community; EXP; Experiment; Field observation; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Irradiance; Net calcification rate of calcium carbonate; Net community production, carbon dioxide, standard deviation; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); pH; Primary production/Photosynthesis; Rocky-shore community; Salinity; Sampling date; Temperature, water; Time, standard deviation; Time in hours; Tropical; Type
    Type: Dataset
    Format: text/tab-separated-values, 1440 data points
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  • 2
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2017. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 122 (2017): 745–761, doi:10.1002/2016JC012326.
    Description: Coral reefs are built of calcium carbonate (CaCO3) produced biogenically by a diversity of calcifying plants, animals, and microbes. As the ocean warms and acidifies, there is mounting concern that declining calcification rates could shift coral reef CaCO3 budgets from net accretion to net dissolution. We quantified net ecosystem calcification (NEC) and production (NEP) on Dongsha Atoll, northern South China Sea, over a 2 week period that included a transient bleaching event. Peak daytime pH on the wide, shallow reef flat during the nonbleaching period was ∼8.5, significantly elevated above that of the surrounding open ocean (∼8.0–8.1) as a consequence of daytime NEP (up to 112 mmol C m−2 h−1). Diurnal-averaged NEC was 390 ± 90 mmol CaCO3 m−2 d−1, higher than any other coral reef studied to date despite comparable calcifier cover (25%) and relatively high fleshy algal cover (19%). Coral bleaching linked to elevated temperatures significantly reduced daytime NEP by 29 mmol C m−2 h−1. pH on the reef flat declined by 0.2 units, causing a 40% reduction in NEC in the absence of pH changes in the surrounding open ocean. Our findings highlight the interactive relationship between carbonate chemistry of coral reef ecosystems and ecosystem production and calcification rates, which are in turn impacted by ocean warming. As open-ocean waters bathing coral reefs warm and acidify over the 21st century, the health and composition of reef benthic communities will play a major role in determining on-reef conditions that will in turn dictate the ecosystem response to climate change.
    Description: NSF Grant Number: 1220529
    Description: 2017-07-31
    Keywords: Coral reef ; Ocean acidification ; Calcification ; Photosynthesis ; Coral bleaching
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: The importance of temperature in regulating physiological processes is without question; however, the interpretation of the relationship between temperature and ecological data is much more complicated. Consequently, it is difficult to decide how the nature of the temperature response terms should be included in models used to predict responses of microbial processes to increasing regional temperature. This analysis compiles several years of data from a research programme conducted in Chesapeake Bay, in an effort to examine how individual microbial processes − as well as the balance between autotrophy and heterotrophy − have responded to temperature, and to predict changes in microbial trophic state based on realistic increases in global temperature. The upper boundary on all of the pelagic microbial rate processes that were measured could be described remarkably well as a linear function of temperature, although there was substantial scatter in the data. Pelagic microbial rate processes (e.g. phytoplankton production, respiration, bacterial productivity) showed a remarkably constrained range of Q10 values from 1.7 to 3.4. The one notable exception to this was nitrogen uptake in the North and Mid Bay, which exhibited Q10 values 〈 1.0. Proxies for phytoplankton biomass (e.g. chlorophyll) were largely independent of temperature while bacterial abundance was significantly related to temperature and was found to have a Q10 of 1.88.    Using these individual temperature responses, the balance of autotrophy and heterotrophy was assessed by calculating the community photosynthesis to respiration (P:R), NH4+ uptake to regeneration (U:R) and phytoplankton to bacterial productivity (PP:BP) ratios for current conditions (all ratios) and for a 2 and 5 °C temperature increase (NH4+ U:R excluded). The NH4+ U:R ratio stayed remarkable constant at ∼1 over the entire temperature range supporting the importance of regenerative processes to nitrogen availability even during periods of heavy allochthonous inputs. These elevated temperature calculations for P:R and PP:BP suggest that the magnitude of autotrophic production during the spring bloom may decrease with increased regional temperature and, as a consequence, the Chesapeake Bay might become net heterotrophic on an annual timescale. These calculations should be considered with caution, but nonetheless demonstrate that the impact of increasing temperature on the balance of autotrophic and heterotrophic processes needs to be researched further.
    Type of Medium: Electronic Resource
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  • 4
    Publication Date: 2019-05-23
    Description: Lakes and reservoirs play an important role in the carbon cycle, and therefore monitoring their metabolic rates is essential. The triple oxygen-isotope anomaly of dissolved O2 [17Δ =  ln(1+δ17O) − 0.518  ×  ln(1 + δ18O)] offers a new, in situ, perspective on primary production, yet little is known about 17Δ from freshwater systems. We investigated the 17Δ together with the oxygen : argon ratio [Δ(O2 ∕ Ar)] in the subtropical Feitsui Reservoir in Taiwan from June 2014 to July 2015. Here, we present the seasonal variations in 17Δ, GP (gross production), NP (net production) and the NP ∕ GP (net to gross ratio) in association with environmental parameters. The 17Δ varied with depth and season, with values ranging between 26 and 205 per meg. The GP rates were observed to be higher (702 ± 107 mg C m−2 d−1) in winter than those (303 ± 66 mg C m−2 d−1) recorded during the summer. The overall averaged GP was 220 g C m−2 yr−1 and NP was −3 g C m−2 yr−1, implying the reservoir was net heterotrophic on an annual basis. This is due to negative NP rates from October to February (−198 ± 78 mg C m−2 d−1). Comparisons between GP rates obtained from the isotope mass balance approach and 14C bottle incubation method (14C–GP) showed consistent values on the same order of magnitude with a GP ∕ 14C–GP ratio of 1.2 ± 1.1. Finally we noted that, although typhoon occurrences were scarce, higher than average 17Δ values and GP rates were recorded after typhoon events.
    Type: Article , PeerReviewed
    Format: text
    Format: text
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