Chris Langdon
University of Miami, Marine Biology and Ecology, Faculty Member
In this paper, we outline the need for a coordinated international effort toward the building of an open-access Global Ocean Oxygen Database and ATlas (GO2DAT) complying with the FAIR principles (Findable, Accessible, Interoperable, and... more
In this paper, we outline the need for a coordinated international effort toward the building of an open-access Global Ocean Oxygen Database and ATlas (GO2DAT) complying with the FAIR principles (Findable, Accessible, Interoperable, and Reusable). GO2DAT will combine data from the coastal and open ocean, as measured by the chemical Winkler titration method or by sensors (e.g., optodes, electrodes) from Eulerian and Lagrangian platforms (e.g., ships, moorings, profiling floats, gliders, ships of opportunities, marine mammals, cabled observatories). GO2DAT will further adopt a community-agreed, fully documented metadata format and a consistent quality control (QC) procedure and quality flagging (QF) system. GO2DAT will serve to support the development of advanced data analysis and biogeochemical models for improving our mapping, understanding and forecasting capabilities for ocean O2 changes and deoxygenation trends. It will offer the opportunity to develop quality-controlled data syn...
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The concentration of CO2 in the atmosphere is projected to reach twice the preindustrial level by the middle of the 21st century. This increase will reduce the concentration of [CO3]2- of the surface ocean by 30% relative to the... more
The concentration of CO2 in the atmosphere is projected to reach twice the preindustrial level by the middle of the 21st century. This increase will reduce the concentration of [CO3]2- of the surface ocean by 30% relative to the preindustrial level and will reduce the calcium carbonate saturation state of the surface ocean by an equal percentage. Using the large 2650 m3 coral reef mesocosm at the BIOSPHERE-2 facility near Tucson, Arizona, we investigated the effect of the projected changes in seawater carbonate chemistry on the calcification of coral reef organisms at the community scale. Our experimental design was to obtain a long (3.8 years) time series of the net calcification of the complete system and all relevant physical and chemical variables (temperature, salinity, light, nutrients, Ca2+,pCO2, TCO2, and total alkalinity). Periodic additions of NaHCO3, Na2CO3, and/or CaCl2 were made to change the calcium carbonate saturation state of the water. We found that there were consistent and reproducible changes in the rate of calcification in response to our manipulations of the saturation state. We show that the net community calcification rate responds to manipulations in the concentrations of both Ca2+ and [CO3]2- and that the rate is well described as a linear function of the ion concentration product, [Ca2+]0.69[[CO3]2-]. This suggests that saturation state or a closely related quantity is a primary environmental factor that influences calcification on coral reefs at the ecosystem level. We compare the sensitivity of calcification to short-term (days) and long-term (months to years) changes in saturation state and found that the response was not significantly different. This indicates that coral reef organisms do not seem to be able to acclimate to changing saturation state. The predicted decrease in coral reef calcification between the years 1880 and 2065 A.D. based on our long-term results is 40%. Previous small-scale, short-term organismal studies predicted a calcification reduction of 14-30%. This much [...]
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Eight-month-old blocks of the coral Porites lobata colonized by natural Hawaiian euendolithic and epilithic communities were experimentally exposed to two different aqueous pCO2 treatments, 400 ppmv and 750 ppmv, for 3 months. The... more
Eight-month-old blocks of the coral Porites lobata colonized by natural Hawaiian euendolithic and epilithic communities were experimentally exposed to two different aqueous pCO2 treatments, 400 ppmv and 750 ppmv, for 3 months. The chlorophyte Ostreobium quekettii dominated communities at the start and at the end of the experiment (65-90%). There were no significant differences in the relative abundance of euendolithic species, nor were there any differences in bioeroded area at the surface of blocks (27%) between pCO2 treatments. The depth of penetration of filaments of O. quekettii was, however, significantly higher under 750 ppmv (1.4 mm) than under 400 ppmv (1 mm). Consequently, rates of carbonate dissolution measured under elevated pCO2 were 48% higher than under ambient pCO2 (0.46 kg CaCO3 dissolved m2/a versus 0.31 kg /m2/a). Thus, biogenic dissolution of carbonates by euendoliths in coral reefs may be a dominant mechanism of carbonate dissolution in a more acidic ocean.
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An investigation was conducted to determine the effects of elevated pCO2 on the net production and calcification of an assemblage of corals maintained under near-natural conditions of temperature, light, nutrient, and flow. Experiments... more
An investigation was conducted to determine the effects of elevated pCO2 on the net production and calcification of an assemblage of corals maintained under near-natural conditions of temperature, light, nutrient, and flow. Experiments were performed in summer and winter to explore possible interactions between seasonal change in temperature and irradiance and the effect of elevated pCO2. Particular attention was paid to interactions between net production and calcification because these two processes are thought to compete for the same internal supply of dissolved inorganic carbon (DIC). A nutrient enrichment experiment was performed because it has been shown to induce a competitive interaction between photosynthesis and calcification that may serve as an analog to the effect of elevated pCO2. Net carbon production, NPC, increased with increased pCO2 at the rate of 3 ± 2% (?mol CO2aq kg?1)?1. Seasonal change of the slope NPC-[CO2aq] relationship was not significant. Calcification (G) was strongly related to the aragonite saturation state ? a . Seasonal change of the G-? a relationship was not significant. The first-order saturation state model gave a good fit to the pooled summer and winter data: G = (8 ± 1 mmol CaCO3 m?2 h?1)(? a ? 1), r 2 = 0.87, P = 0.0001. Both nutrient and CO2 enrichment resulted in an increase in NPC and a decrease in G, giving support to the hypothesis that the cellular mechanism underlying the decrease in calcification in response to increased pCO2 could be competition between photosynthesis and calcification for a limited supply of DIC.
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Research Interests: Earth Sciences, Environmental Science, Oceanography, Animal Science, Time Series, and 15 moreBiological Sciences, Seasonality, Environmental Sciences, Biosphere, Coral Reef, Respiration, Biological Oceanography and Limnology, Coral, Primary Production, Dissolved Oxygen, Organic carbon, Reef, Biome, Community Respiration, and Closed system
Research Interests: Earth Sciences, Environmental Science, Oceanography, Biomass, Productivity, and 15 morePhytoplankton, Biological Sciences, Environmental Sciences, Plankton, Biological Oceanography and Limnology, Seasonal variation, Primary Production, Sea Water, Primary productivity, North American, Gulf Stream, Chlorophyll a, Mixed layer, Specific Growth Rate, and Production Rate
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There is growing evidence that different coral species and algal symbionts (Symbiodinium spp.) can vary greatly in their response to rising temperatures and also ocean acidification. In a fully crossed factorial experimental design, two... more
There is growing evidence that different coral species and algal symbionts (Symbiodinium spp.) can vary greatly in their response to rising temperatures and also ocean acidification. In a fully crossed factorial experimental design, two threatened Caribbean reef‐building coral species, Acropora cervicornis hosting a mixture of Symbiodinium clades A and C and Orbicella faveolata hosting Symbiodinium D, were exposed to combinations of a normal (26°C) and elevated (32°C) temperature and normal (380 ppm) and elevated (800 ppm) CO2 for 62 d and then recovered at 26°C and 380 ppm or 32°C and 380 ppm for an additional 56 d. CO2 enrichment did not confer enhanced thermal tolerance as had been suggested in other studies. A. cervicornis was more sensitive to heat stress (maximum monthly mean + 1.5°C) experiencing 100% mortality after 25 d while all O. faveolata survived. Conversely, O. faveolata was more sensitive to high CO2 experiencing a 47% reduction in growth while A. cervicornis experienced no significant reduction. It is predicted that A. cervicornis is unlikely to survive past 2035. O. faveolata with D symbionts might survive to 2060 and later but its abundance will be impacted by CO2 effects on recruitment potential.
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Effective data management plays a key role in oceanographic research as cruise-based data, collected from different laboratories and expeditions, are commonly compiled to investigate regional to global oceanographic processes. Here we... more
Effective data management plays a key role in oceanographic research as cruise-based data, collected from different laboratories and expeditions, are commonly compiled to investigate regional to global oceanographic processes. Here we describe new and updated best practice data standards for discrete chemical oceanographic observations, specifically those dealing with column header abbreviations, quality control flags, missing value indicators, and standardized calculation of certain properties. These data standards have been developed with the goals of improving the current practices of the scientific community and promoting their international usage. These guidelines are intended to standardize data files for data sharing and submission into permanent archives. They will facilitate future quality control and synthesis efforts and lead to better data interpretation. In turn, this will promote research in ocean biogeochemistry, such as studies of carbon cycling and ocean acidificati...
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The effect of elevated pCO2 on the metabolism of a coral reef community dominated by macroalgae has been investigated utilizing the large 2650 m3 coral reef mesocosm at the Biosphere-2 facility near Tucson, Arizona. The carbonate... more
The effect of elevated pCO2 on the metabolism of a coral reef community dominated by macroalgae has been investigated utilizing the large 2650 m3 coral reef mesocosm at the Biosphere-2 facility near Tucson, Arizona. The carbonate chemistry of the water was manipulated to simulate present-day and a doubled CO2 future condition. Each experiment consisted of a 1-2 month preconditioning period followed by a 7-9 day observational period. The pCO2 was 404 ± 63 ?atm during the present-day pCO2 experiment and 658 ± 59 ?atm during the elevated pCO2 experiment. Nutrient levels were low and typical of natural reefs waters (NO3? 0.5-0.9 ?M, NH4+ 0.4 ?M, PO43? 0.07-0.09 ?M). The temperature and salinity of the water were held constant at 26.5 ± 0.2°C and 34.4 ± 0.2 ppt. Photosynthetically available irradiance was 10 ± 2 during the present-day experiment and 7.4 ± 0.5 mol photons m?2 d?1 during the elevated pCO2 experiment. The primary producer biomass in the mesocosm was dominated by four species of macroalgae; Haptilon cubense, Amphiroa fragillisima, Gelidiopsis intricata and Chondria dasyphylla. Algal biomass was 10.4 mol C m?2 during the present-day and 8.7 mol C m?2 and during the elevated pCO2 experiments. As previously observed, the increase in pCO2 resulted in a decrease in calcification from 0.041 ± 0.007 to 0.006 ± 0.003 mol CaCO3 m?2 d?1. Net community production (NCP) and dark respiration did not change in response to elevated pCO2. Light respiration measured by a new radiocarbon isotope dilution method exceeded dark respiration by a factor of 1.2 ± 0.3 to 2.1 ± 0.4 on a daily basis and by 2.2 ± 0.6 to 3.9 ± 0.8 on an hourly basis. The 1.8-fold increase with increasing pCO2 indicates that the enhanced respiration in the light was not due to photorespiration. Gross production (GPP) computed as the sum of NCP plus daily respiration (light + dark) increased significantly (0.24 ± 0.03 vs. 0.32 ± 0.04 mol C m?2 d?1). However, the conventional calculation of GPP based on the assumption that respiration in the light proce [...]
Research Interests: Oceanography, Chemistry, Biology, Cnidaria, Carbonate, and 4 moreCoral Reef, Seawater, Coral, and Reef
Mussels use their shells for protection which they can thicken or grow in response to predator cues, commonly referred to as an inducible defense. Oceans are experiencing elevated pCO2 due to climate change. Elevated pCO2 can have... more
Mussels use their shells for protection which they can thicken or grow in response to predator cues, commonly referred to as an inducible defense. Oceans are experiencing elevated pCO2 due to climate change. Elevated pCO2 can have negative effects on bivalve morphology and physiology, but we are still learning about the consequences of these effects on predator-prey interactions, a key motivation of this study. Using a 4 wk (short-term) laboratory experiment, we orthogonally manipulated 2 levels of pCO2 (ambient or elevated to predicted future conditions that mimicked diel variability) and 2 levels of predator presence (absent or present) of blue crabs Callinectes sapidus to determine their effects on the morphology and predator handling times on southern ribbed mussels Geukensia granosissima. Experimental results indicated that shell length and width increased in mussels in response to the predator cues, and these inducible defenses were not affected by elevated pCO2. Unexpectedly,...
Research Interests: Zoology, Climate Change, Biology, Ecology, Predation, and 4 morePredator, Estuary, Interspecific competition, and Mussel
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In response to the increases in pCO2 projected in the 21st century, adult coral growth and calcification are expected to decrease significantly. However, no published studies have investigated the effect of elevated pCO2 on earlier life... more
In response to the increases in pCO2 projected in the 21st century, adult coral growth and calcification are expected to decrease significantly. However, no published studies have investigated the effect of elevated pCO2 on earlier life history stages of corals. Porites astreoides larvae were collected from reefs in Key Largo, Florida, USA, settled and reared in controlled saturation state seawater. Three saturation states were obtained, using 1 M HCl additions, corresponding to present (380 ppm) and projected pCO2 scenarios for the years 2065 (560 ppm) and 2100 (720 ppm). The effect of saturation state on settlement and post-settlement growth was evaluated. Saturation state had no significant effect on percent settlement; however, skeletal extension rate was positively correlated with saturation state, with ~50% and 78% reductions in growth at the mid and high pCO2 treatments compared to controls, respectively.
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ABSTRACT A study was conducted to investigate how corals may be impacted by the combination of rising temperature and declining pH. In a fully crossed experimental design two important Caribbean reef-building coral species Acropora... more
ABSTRACT A study was conducted to investigate how corals may be impacted by the combination of rising temperature and declining pH. In a fully crossed experimental design two important Caribbean reef-building coral species Acropora cervicornis and Montastraea faveolata were exposed to combinations of a normal (26°C) and elevated (32°C) temperature and normal (380 ppm) and elevated (800 ppm) CO2 level. Nine colonies of each species were placed in eight tanks. Two tanks were assigned to each of the four temperature and CO2 combinations. The CO2 level was controlled by bubbling with either outside air or outside air enriched with CO2 gas to achieve the desired CO2 concentration in the tank. Corals were pre-conditioned for 39 days under 26°C and 380 ppm. The temperature and CO2 in the experimental tanks was then ramped up at a rate of 0.3°C and 30 ppm per day over a two week period. The skeletal growth of the corals was measured weekly over 62 days using an optical or laser micrometer. At the end of the high temperature and CO2 part the experiment the ability of the corals to recover from these stressful conditions was examined for 56 days. The CO2 in the high CO2 tanks was reduced to 380 ppm and the temperature in the 32°C 380 tanks was reduced to 26°C. This experiment is our second attempt to measure short term changes in skeletal growth as a function of temperature and CO2. In the first year none of the corals grew. We eventually discovered that supplemental feeding was necessary. The results of the second year's experiment are interesting but exhibit a great deal of variability. Forty-four percent of A. cervicornis colonies exhibited a decline in growth of 45% and seventy-seven percent of the M. faveolata colonies experienced a decline of 44% under 800 ppm and recovered quickly when the CO2 was lowered to 380 ppm during the recovery phase. However, the other colonies either failed to grow at all, showed no response to CO2 or seemed to grow more quickly under elevated CO2. The variability may be a result of the technical difficulties of measuring very small changes in height that we are still working out or could reflect that skeletal growth is a much more complex process than calcification. All A. cervicornis colonies exposed to 32°C bleached and died within a few weeks regardless of the CO2 level. The M. faveolata colonies paled but did not bleach at 32°C and 380 or 800 ppm even after 17 weeks. Growth at 32°C and 380 or 800 ppm was not significantly different from zero. When conditions in the 32°C and 380 ppm or 32°C and 800 ppm tanks were changed to 26°C and 380 ppm all the M. faveolata colonies quickly recovered to pre-experiment growth rates. We conclude that by the end of the century conditions could reach the point that A. cervicornis will not be able to survive, i.e. summer conditions will result in large percentage of the colonies bleaching and dying. The situation for M. faveolata is that colonies will be able to survive but might grow at 45% of present day rates during the cooler months of the year and not at all during the hottest parts of the summer.
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We collected in situ bio-optical and physical oceanographic data using the MVMS (Multi-Variable Moored System) 34N 70W in the Sargasso Sea for nine months in 1987 in the upper 160 meters. The sampled oceanographic parameters include... more
We collected in situ bio-optical and physical oceanographic data using the MVMS (Multi-Variable Moored System) 34N 70W in the Sargasso Sea for nine months in 1987 in the upper 160 meters. The sampled oceanographic parameters include temperature, currents, photosynthetically available radiation, beam attenuation coefficient, stimulated fluorescence, and dissolved oxygen concentration. Meteorological measurements were made, and sea surface temperature maps and Geosat altimetry data were used to investigate the mesoscale field associated with the dynamics of the Gulf Stream. Time series indicate seasonal cycling of heat and momentum fields, the diel cycle in bio-optical variables, episodic events related to advected water masses and local meteorological forcing, a phytoplankton bloom concentrated at 20 meters during the spring, and the development of sub-subsurface chlorophyll and particle maxima during the summer. Spectral analysis reveals a correspondence between internal wave and bio-optical variability. High-resolution time series of gross primary production were estimated with the Kiefer-Mitchell model using the time series of stimulated fluorescence and PAR as input. Particle production rate also was calculated using the time series of beam attenuation coefficient. By combining the two estimates, time series of Chl: Cratio were created. Our results show that high-frequency sampling (minimizing aliasing) is essential in revealing the dynamical changes occurring in upper ocean primary productivity and carbon flux.
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The concentration of CO2 in the atmosphere is projected to reach twice the preindustrial level by the middle of the 21st century. This increase will reduce the concentration of [CO3]2- of the surface ocean by 30% relative to the... more
The concentration of CO2 in the atmosphere is projected to reach twice the preindustrial level by the middle of the 21st century. This increase will reduce the concentration of [CO3]2- of the surface ocean by 30% relative to the preindustrial level and will reduce the calcium carbonate saturation state of the surface ocean by an equal percentage. Using the large 2650 m3 coral reef mesocosm at the BIOSPHERE-2 facility near Tucson, Arizona, we investigated the effect of the projected changes in seawater carbonate chemistry on the calcification of coral reef organisms at the community scale. Our experimental design was to obtain a long (3.8 years) time series of the net calcification of the complete system and all relevant physical and chemical variables (temperature, salinity, light, nutrients, Ca2+,pCO2, TCO2, and total alkalinity). Periodic additions of NaHCO3, Na2CO3, and/or CaCl2 were made to change the calcium carbonate saturation state of the water. We found that there were consistent and reproducible changes in the rate of calcification in response to our manipulations of the saturation state. We show that the net community calcification rate responds to manipulations in the concentrations of both Ca2+ and [CO3]2- and that the rate is well described as a linear function of the ion concentration product, [Ca2+]0.69[[CO3]2-]. This suggests that saturation state or a closely related quantity is a primary environmental factor that influences calcification on coral reefs at the ecosystem level. We compare the sensitivity of calcification to short-term (days) and long-term (months to years) changes in saturation state and found that the response was not significantly different. This indicates that coral reef organisms do not seem to be able to acclimate to changing saturation state. The predicted decrease in coral reef calcification between the years 1880 and 2065 A.D. based on our long-term results is 40%. Previous small-scale, short-term organismal studies predicted a calcification reduction of 14-30%. This much [...]
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Syntheses of carbonate chemistry spatial patterns are important for predicting ocean acidification impacts, but are lacking in coastal oceans. Here, we show that along the North American Atlantic and Gulf coasts the meridional... more
Syntheses of carbonate chemistry spatial patterns are important for predicting ocean acidification impacts, but are lacking in coastal oceans. Here, we show that along the North American Atlantic and Gulf coasts the meridional distributions of dissolved inorganic carbon (DIC) and carbonate mineral saturation state (Ω) are controlled by partial equilibrium with the atmosphere resulting in relatively low DIC and high Ω in warm southern waters and the opposite in cold northern waters. However, pH and the partial pressure of CO2 (pCO2) do not exhibit a simple spatial pattern and are controlled by local physical and net biological processes which impede equilibrium with the atmosphere. Along the Pacific coast, upwelling brings subsurface waters with low Ω and pH to the surface where net biological production works to raise their values. Different temperature sensitivities of carbonate properties and different timescales of influencing processes lead to contrasting property distributions ...
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Macroalgae and benthic cyanobacteria are becoming increasingly abundant on reefs, and many of these dominant algae produce diverse secondary metabolites. Abundant brown and green macroalgae and nuisance blooms of cyanobacteria occur... more
Macroalgae and benthic cyanobacteria are becoming increasingly abundant on reefs, and many of these dominant algae produce diverse secondary metabolites. Abundant brown and green macroalgae and nuisance blooms of cyanobacteria occur regularly throughout Florida and on the Belizean barrier reef. Crude extracts and compounds from some macroalgae and cyanobacteria deter feeding by natural assemblages of fishes and the sea urchin Diadema antillarum. In addition, macroalgal and cyanobacterial secondary metabolites may serve multiple ecological functions, including inhibition of microorganisms and competition for space. The role of allelopathy (chemical inhibition) in mediating the interactions between chemically rich species of algae and cyanobacteria and different life history stages of corals was tested. Extracts and isolated compounds from Dictyota spp., Lyngbya spp. and other cyanobacteria negatively influenced the settlement and metamorphosis of coral larvae. On reefs experiencing increased abundance of chemically defended macroalgae and benthic cyanobacteria, the restocking of adult coral populations may be slowed due to recruitment inhibition caused by algal secondary metabolites. These compounds protect some algae from herbivory (allowing increased space occupation) and reduce coral recruitment, both of which may perpetuate a “phase shift” from coral to algal dominated communities. Increases in atmospheric carbon dioxide concentrations are reducing ocean pH and the calcification rates of marine organisms. Changes in CO2 concentrations may also cause sub-lethal stress and changes in concentrations of secondary metabolites that protect macroalgae from herbivores. We exposed two chemically-rich algae, the calcareous, terpene-producing macroalga Halimeda opuntia and the benthic marine cyanobacterium Lyngbya cf. confervoides, to seawater conditioned with increasing levels of CO2 to test for effects of ocean acidification on growth, calcification, and secondary metabolite concentrations. Although terpene concentrations were not affected in H. opuntia, calcification decreased at CO2 concentrations of 2200 ppm and above, which could increase its susceptibility to herbivory. We found no effect on growth rates over the range of CO2 concentrations and temperatures tested for Lyngbya cf. confervoides. Halimeda opuntia and benthic cyanobacteria are conspicuous community members on coral reefs and in seagrass beds in tropical seas around the world, and the observed tolerance of these algae to ocean acidification suggests that they will continue to be abundant in a changing ocean.
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... Factors controlling the rate of CaCO 3 precipitation on Great Bahama Bank. Auteur(s) / Author(s). BROECKER Wallace S. (1) ; LANGDON Chris (1) ; TAKAHASHI Taro (1) ; PENG Tsung-Hung (2) ; Affiliation(s) du ou des auteurs / Author(s)... more
... Factors controlling the rate of CaCO 3 precipitation on Great Bahama Bank. Auteur(s) / Author(s). BROECKER Wallace S. (1) ; LANGDON Chris (1) ; TAKAHASHI Taro (1) ; PENG Tsung-Hung (2) ; Affiliation(s) du ou des auteurs / Author(s) Affiliation(s). ...