Ocean acidification impacts primary and bacterial production in Antarctic coastal waters during austral summer

Abstract. Ecophysiological studies on Antarctic cryptophytes to assess whether climatic changes such as ocean acidification and enhanced stratification affect their growth in Antarctic coastal waters in the future are lacking so far. This is the first study that investigates the combined effects of the increasing availability of pCO2 (400 and 1000 µatm) and irradiance (20, 200 and 500 µmol photons m−2 s−1) on growth, elemental composition and photophysiology of the Antarctic cryptophyte Geminigera cryophila. Under ambient pCO2, this species was characterized by a pronounced sensitivity to increasing irradiance with complete growth inhibition at the highest light intensity. Interestingly, when grown under high pCO2 this negative light effect vanished, and it reached the highest rates of growth and particulate organic carbon production at the highest irradiance compared to the other tested experimental conditions. Our results for G. cryophila reveal beneficial effects of ocean acidification in conjunction with enhanced irradiance on growth and photosynthesis. Hence, cryptophytes such as G. cryophila may be potential winners of climate change, potentially thriving better in more stratified and acidic coastal waters and contributing in higher abundance to future phytoplankton assemblages of coastal Antarctic waters.

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Upwelling Bays: How Coastal Upwelling Controls Circulation, Habitat, and Productivity in Bays

Annual Review of Marine Science ◽

10.1146/annurev-marine-010419-011020 ◽

2020 ◽

Vol 12 (1) ◽

pp. 415-447 ◽

Cited By ~ 8

Author(s):

John L. Largier

Keyword(s):

Ocean Acidification ◽

Wind Stress ◽

Coastal Waters ◽

Coastal Upwelling ◽

Coastal Currents ◽

Local Wind ◽

Phytoplankton Blooms ◽

Local Extrema ◽

High Recruitment

Bays in coastal upwelling regions are physically driven and biochemically fueled by their interaction with open coastal waters. Wind-driven flow over the shelf imposes a circulation in the bay, which is also influenced by local wind stress and thermal bay–ocean density differences. Three types of bays are recognized based on the degree of exposure to coastal currents and winds (wide-open bays, square bays, and elongated bays), and the characteristic circulation and stratification patterns of each type are described. Retention of upwelled waters in bays allows for dense phytoplankton blooms that support productive bay ecosystems. Retention is also important for the accumulation of larvae, which accounts for high recruitment in bays. In addition, bays are coupled to the shelf ecosystem through export of plankton-rich waters during relaxation events. Ocean acidification and deoxygenation are a concern in bays because local extrema can develop beneath strong stratification.

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Ocean acidification disrupts the orientation of postlarval Caribbean spiny lobsters

Scientific Reports ◽

10.1038/s41598-020-75021-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Philip M. Gravinese ◽

Heather N. Page ◽

Casey B. Butler ◽

Angelo Jason Spadaro ◽

Clay Hewett ◽

...

Keyword(s):

Ocean Acidification ◽

Time Scales ◽

Coastal Waters ◽

Chemical Cues ◽

Spiny Lobster ◽

Episodic Acidification ◽

Anthropogenic Inputs ◽

Seawater Ph ◽

Y Maze ◽

The Caribbean

Abstract Anthropogenic inputs into coastal ecosystems are causing more frequent environmental fluctuations and reducing seawater pH. One such ecosystem is Florida Bay, an important nursery for the Caribbean spiny lobster, Panulirus argus. Although adult crustaceans are often resilient to reduced seawater pH, earlier ontogenetic stages can be physiologically limited in their tolerance to ocean acidification on shorter time scales. We used a Y-maze chamber to test whether reduced-pH seawater altered the orientation of spiny lobster pueruli toward chemical cues produced by Laurencia spp. macroalgae, a known settlement cue for the species. We tested the hypothesis that pueruli conditioned in reduced-pH seawater would be less responsive to Laurencia spp. chemical cues than pueruli in ambient-pH seawater by comparing the proportion of individuals that moved to the cue side of the chamber with the proportion that moved to the side with no cue. We also recorded the amount of time (sec) before a response was observed. Pueruli conditioned in reduced-pH seawater were less responsive and failed to select the Laurencia cue. Our results suggest that episodic acidification of coastal waters might limit the ability of pueruli to locate settlement habitats, increasing postsettlement mortality.

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Temporal Variation of Bacterial Respiration and Growth Efficiency in Tropical Coastal Waters

Applied and Environmental Microbiology ◽

10.1128/aem.01227-09 ◽

2009 ◽

Vol 75 (24) ◽

pp. 7594-7601 ◽

Cited By ~ 30

Author(s):

Choon Weng Lee ◽

Chui Wei Bong ◽

Yii Siang Hii

Keyword(s):

Temporal Variation ◽

Bacterial Growth ◽

Coastal Waters ◽

Bacterial Production ◽

Growth Efficiency ◽

Bacterial Growth Efficiency ◽

Bacterial Respiration ◽

Substrate Quality ◽

Carbon Demand ◽

Net Heterotrophy

ABSTRACT We investigated the temporal variation of bacterial production, respiration, and growth efficiency in the tropical coastal waters of Peninsular Malaysia. We selected five stations including two estuaries and three coastal water stations. The temperature was relatively stable (averaging around 29.5°C), whereas salinity was more variable in the estuaries. We also measured dissolved organic carbon and nitrogen (DOC and DON, respectively) concentrations. DOC generally ranged from 100 to 900 μM, whereas DON ranged from 0 to 32 μM. Bacterial respiration ranged from 0.5 to 3.2 μM O2 h−1, whereas bacterial production ranged from 0.05 to 0.51 μM C h−1. Bacterial growth efficiency was calculated as bacterial production/(bacterial production + respiration), and ranged from 0.02 to 0.40. Multiple correlation analyses revealed that bacterial production was dependent upon primary production (r2 = 0.169, df = 31, and P < 0.02) whereas bacterial respiration was dependent upon both substrate quality (i.e., DOC/DON ratio) (r2 = 0.137, df = 32, and P = 0.03) and temperature (r2 = 0.113, df = 36, and P = 0.04). Substrate quality was the most important factor (r2 = 0.119, df = 33, and P = 0.04) for the regulation of bacterial growth efficiency. Using bacterial growth efficiency values, the average bacterial carbon demand calculated was from 5.30 to 11.28 μM C h−1. When the bacterial carbon demand was compared with primary productivity, we found that net heterotrophy was established at only two stations. The ratio of bacterial carbon demand to net primary production correlated significantly with bacterial growth efficiency (r2 = 0.341, df = 35, and P < 0.001). From nonlinear regression analysis, we found that net heterotrophy was established when bacterial growth efficiency was <0.08. Our study showed the extent of net heterotrophy in these waters and illustrated the importance of heterotrophic microbial processes in coastal aquatic food webs.

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The contribution of heterotrophic nanoflagellate grazing towards bacterial mortality in tropical waters: comparing estuaries and coastal ecosystems

Marine and Freshwater Research ◽

10.1071/mf10213 ◽

2011 ◽

Vol 62 (4) ◽

pp. 414 ◽

Cited By ~ 9

Author(s):

Chui Wei Bong ◽

Choon Weng Lee

Keyword(s):

Coastal Waters ◽

Bacterial Production ◽

Trophic Status ◽

Bacterial Abundance ◽

Temperature Optimum ◽

Viral Lysis ◽

Tropical Waters ◽

Order Of Magnitude ◽

Heterotrophic Nanoflagellate ◽

Straits Of Malacca

Heterotrophic nanoflagellate (HNF) grazing depends on both temperature and trophic status of an ecosystem. As most microbes already function at their temperature optimum in tropical waters, we hypothesised that HNF grazing rates would be higher in more productive sites such as estuaries than in less productive areas such as coastal waters. We sampled two estuaries and three coastal sites along the Straits of Malacca and the South China Sea near the Malaysia Peninsula. Bacterial abundance ranged 0.9–6.3 × 106 cells mL–1, whereas HNF abundance ranged 1.8–10.1 ×103 cells mL–1. Bacterial production ranged 1.1–12.7 × 105 cells mL–1 h–1, whereas HNF grazing rates were an order of magnitude lower at 1.0–78.5 × 104 cells mL–1 h–1. Bacterial abundance, net bacterial production and HNF grazing rates were higher in estuaries than coastal waters but HNF abundance did not differ between the two areas. Across all stations, HNF grazing rates increased with bacterial production, and accounted for ~33% of bacterial production. Our results suggest that in the tropical waters studied, there was a bacterial production–grazing imbalance. Other loss factors such as viral lysis, sedimentation or the presence of benthic filter feeders could account for this imbalance.

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Biogeochemical feedbacks to ocean acidification in a cohesive photosynthetic sediment

Scientific Reports ◽

10.1038/s41598-021-02314-y ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kay Vopel ◽

Alexis Marshall ◽

Shelly Brandt ◽

Adam Hartland ◽

Charles K. Lee ◽

...

Keyword(s):

Ocean Acidification ◽

Coastal Waters ◽

Metabolic Response ◽

Sediment Cores ◽

Biogeochemical Processes ◽

Ambient Seawater ◽

Calcite Dissolution ◽

Sand Control ◽

Negative Effect ◽

And Control

AbstractEcosystem feedbacks in response to ocean acidification can amplify or diminish diel pH oscillations in productive coastal waters. Benthic microalgae generate such oscillations in sediment porewater and here we ask how CO2 enrichment (acidification) of the overlying seawater alters these in the absence and presence of biogenic calcite. We placed a 1-mm layer of ground oyster shells, mimicking the arrival of dead calcifying biota (+Calcite), or sand (Control) onto intact silt sediment cores, and then gradually increased the pCO2 in the seawater above half of +Calcite and Control cores from 472 to 1216 μatm (pH 8.0 to 7.6, CO2:HCO3− from 4.8 to 9.6 × 10−4). Porewater [O2] and [H+] microprofiles measured 16 d later showed that this enrichment had decreased the O2 penetration depth (O2-pd) in +Calcite and Control, indicating a metabolic response. In CO2-enriched seawater: (1) sediment biogeochemical processes respectively added and removed more H+ to and from the sediment porewater in darkness and light, than in ambient seawater increasing the amplitude of the diel porewater [H+] oscillations, and (2) in darkness, calcite dissolution in +Calcite sediment decreased the porewater [H+] below that in overlying seawater, reversing the sediment–seawater H+ flux and decreasing the amplitude of diel [H+] oscillations. This dissolution did not, however, counter the negative effect of CO2 enrichment on O2-pd. We now hypothesise that feedback to CO2 enrichment—an increase in the microbial reoxidation of reduced solutes with O2—decreased the sediment O2-pd and contributed to the enhanced porewater acidification.

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Biogeochemical Feedbacks to Ocean Acidification in a Cohesive Photosynthetic Sediment

10.21203/rs.3.rs-431198/v1 ◽

2021 ◽

Author(s):

Kay Vopel ◽

Alexis Marshall ◽

Shelly Brandt ◽

Adam Hartland ◽

Charles K Lee ◽

...

Keyword(s):

Ocean Acidification ◽

Coastal Waters ◽

Metabolic Response ◽

Sediment Cores ◽

Ambient Seawater ◽

Dark Light ◽

Sand Control ◽

Negative Effect ◽

And Control ◽

Do So

Abstract Ecosystem feedbacks in response to ocean acidification can amplify or diminish the diel pH oscillations that characterize productive coastal waters. We report that benthic microalgae generate such oscillations in the porewater of cohesive sediment and ask how carbonation (acidification) of the overlying seawater alters these in the absence and presence of biogenic calcite. To do so, we placed a 1-mm layer of ground oyster shells (Treatment) or sand (Control) onto intact sediment cores free of large dwelling fauna, and then gradually increased the pCO2 in the seawater above half of the Treatment and Control cores from 472 to 1216 μatm (pH 8.0 to 7.6, CO2:HCO3- from 4.8 to 9.6 x 10-4). Vertical porewater [O2] and [H+] microprofiles measured 16 d later showed that this carbonation had decreased O2 penetration in all cores, indicating a metabolic response. In carbonated seawater: (1) sediment biogeochemical processes added and removed more H+ to and from the porewater in darkness and light, respectively, than in ambient seawater increasing the amplitude of the dark–light porewater [H+] oscillations, and (2) the dissolution of calcite decreased the porewater [H+] below that in overlying seawater, reversing the dark sediment–seawater H+ flux and decreasing the amplitude of diel [H+] oscillations. This dissolution did not, however, counter the negative effect of carbonation on sediment O2 penetration. We hypothesise that the latter effect and the observed enhanced acidification of the sediment porewater were caused by an ecosystem feedback: a CO2-induced increase in the microbial reoxidation of reduced solutes with O2.

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