Nutrient pollution disrupts key ecosystem functions on coral reefs

There is a long history of examining the impacts of nutrient pollution and pH on coral reefs. However, little is known about how these two stressors interact and influence coral reef ecosystem functioning. Using a six-week nutrient addition experiment, we measured the impact of elevated nitrate (NO − 3 ) and phosphate (PO 3− 4 ) on net community calcification (NCC) and net community production (NCP) rates of individual taxa and combined reef communities. Our study had four major outcomes: (i) NCC rates declined in response to nutrient addition in all substrate types, (ii) the mixed community switched from net calcification to net dissolution under medium and high nutrient conditions, (iii) nutrients augmented pH variability through modified photosynthesis and respiration rates, and (iv) nutrients disrupted the relationship between NCC and aragonite saturation state documented in ambient conditions. These results indicate that the negative effect of NO − 3 and PO 3− 4 addition on reef calcification is likely both a direct physiological response to nutrients and also an indirect response to a shifting pH environment from altered NCP rates. Here, we show that nutrient pollution could make reefs more vulnerable to global changes associated with ocean acidification and accelerate the predicted shift from net accretion to net erosion.

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Predicting the impact of ocean acidification on coral reefs: evaluating the assumptions involved

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv091 ◽

2015 ◽

Vol 73 (3) ◽

pp. 550-557 ◽

Cited By ~ 15

Author(s):

Paul L. Jokiel

Keyword(s):

Coral Reefs ◽

Ocean Acidification ◽

Bulk Water ◽

Ion Concentration ◽

Calcification Rate ◽

Saturation State ◽

Simplifying Assumptions ◽

Reef Decline ◽

Highly Correlated ◽

The Impact

Abstract Predictions of future impact of climate change on coral reefs indicate that bleaching mortality due to higher temperature will be the major factor in the decline of coral reefs. Ocean acidification (OA) is increasingly considered to be an important contributing factor, but estimates of its importance vary widely in the literature. Models of future reef decline due to OA generally involve four simplifying assumptions that can lead to contradictions. The assumptions are: (i) Oceanic conditions of Ωarag control or are at least highly correlated with net calcification rate (Gnet) on coral reefs. (ii) Calcification rate is driven by bulk water carbonate ion concentration [CO32−] expressed as Ωarag. (iii) Changes in coral calcification rate can be used to estimate future changes in coral reef calcification rate. (iv) The impact of OA is additive and not synergistic with other environmental factors such as increased temperature. The assumption that aragonite saturation state (Ωarag) of seawater drives calcification is the most widely used and needs to be further evaluated. An alternate hypothesis is that calcification is limited by the ability of the system to rid itself of the protons generated by calcification. Recent studies allow further testing of the assumptions and point the way to resolving shortcomings in our understanding of how OA impacts coral reefs.

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The growing exposure of Pacific coral reefs to compound extremes caused by marine heatwaves coalescing with low saturation state extremes

10.5194/egusphere-egu21-15096 ◽

2021 ◽

Author(s):

Luke Gregor ◽

Nicolas Gruber

Keyword(s):

Pacific Ocean ◽

Coral Reefs ◽

Extreme Events ◽

Anthropogenic Heat ◽

Average Intensity ◽

Saturation State ◽

The Pacific ◽

Compound Events ◽

The Pacific Ocean ◽

The Impact

The ocean has played a key role in mitigating the impact of climate change by taking up excess anthropogenic heat and CO2 leading to warming and increased ocean acidity, which goes in hand with a reduction of the saturation state of seawater with regard to the mineral carbonate aragonite, i.e., &#937;AR. While the threats posed by these long-term changes to marine organisms and ecosystems are well recognized, only more recently has the community realized that these threats might be much more imminent owing to extreme events. This is the result of these extremes exposing vulnerable ecosystems already today to conditions that lie in the far future when considering only the changes in the mean conditions. Of particular concern are so-called compound events, i.e., conditions when both temperatures are extremely hot and the saturation states extremely low, as this compounding might be particularly threatening for marine ecosystems, especially for warm water coral reefs.Here we use satellite records of sea surface temperature (SST) and satellite &#937;AR to map globally the occurrence of marine heat waves (MHW) and low saturation state extreme events and their compounding for the period 1985 and 2018. We use SSTs from the OSTIA product, while we take &#937;AR from the newly developed OceanSODA-ETHZ (monthly 1&#176;x1&#176;) observation-based product that extrapolates ship observations with satellite data. Our study focuses on the Pacific Ocean between 25&#176;S and 25&#176;N, a region with more than 1000 identified coral reefs. We define extremes using the approach of Hobday et al. (2018) with a fixed baseline determined from the entire record (1985-2018) and where extremes are below/above the 10th/90th percentiles for &#937;/SST respectively.The majority of the compound extreme events (too hot and too low saturation state) occur in the western tropical Pacific, with 757 of the 1206 reefs in the Pacific experiencing at least three months of compound extreme events over the entire period. The average duration of these compound extremes was 3.6 months, and the average area was 247 600 km2 (roughly the size of the United Kingdom). The compound events had an average intensity of &#8211;0.13 for &#937;AR&#160;and 0.71&#176;C, where the intensity is the anomaly from the climatology. The largest and longest lasting extreme event started in 2016 and lasted nearly three years, coinciding with the El Ni&#241;o event over the same period, covering an area equivalent to Australia. These findings suggest that more than 60% of coral reefs in the Pacific Ocean are located in regions where heating events may have been compounded by decreased potential for calcification. Given the continuing increase in atmospheric CO2, the severity of this type of compound events is bound to increase in the future.&#160;

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Impact Mechanism of the Ecological Vulnerability of Highly Developed Islands Based on the Bayesian Network Model—Applied to the Changshan Islands

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18084150 ◽

2021 ◽

Vol 18 (8) ◽

pp. 4150

Author(s):

Keyu Qin ◽

Haijun Huang ◽

Jingya Liu ◽

Liwen Yan ◽

Yanxia Liu ◽

...

Keyword(s):

Bayesian Network ◽

Network Model ◽

Geographical Information ◽

Global Changes ◽

Bayesian Network Model ◽

Island Ecosystems ◽

Impact Mechanism ◽

The North ◽

Ecological Vulnerability ◽

The Impact

Islands are one of the most sensitive interfaces between global changes and land and sea dynamic effects, with high sensitivity and low stability. Therefore, under the dynamic coupling effect of human activities and frequent natural disasters, the vulnerability of the ecological environment of islands shows the characteristics of complexity and diversity. For the protection of island ecosystems, a system for the assessment of island ecosystems and studies on the mechanism of island ecological vulnerability are highly crucial. In this study, the North and South Changshan Islands of China were selected as the study area. Considering various impact factors of island ecological vulnerability, the geographical information systems (GIS) spatial analysis, field surveys, data sampling were used to evaluate island ecological vulnerability. The Bayesian network model was used to explore the impact mechanism of ecological vulnerability. The results showed that the ecological vulnerability of the North Changshan Island is higher than that of the South Changshan Island. Among all the indicators, the proportion of net primary productivity (NPP) and the steep slope has the strongest correlation with ecological vulnerability. This study can be used as references in the relevant departments to formulate management policies and promote the sustainable development of islands and their surrounding waters

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COVID-19 Pandemic Turns Life-Science Students into “Citizen Scientists”: Data Indicate Multiple Negative Effects of Urbanization on Biota

Sustainability ◽

10.3390/su13052992 ◽

2021 ◽

Vol 13 (5) ◽

pp. 2992

Author(s):

Jens Schirmel

Keyword(s):

Citizen Science ◽

Online Teaching ◽

Teaching Strategy ◽

Ecosystem Functions ◽

Negative Effects ◽

Ecological Data ◽

Pollinating Insects ◽

Impact Of Urbanization ◽

Data Collections ◽

The Impact

The COVID-19 pandemic and its restrictions strongly affect the higher education community and require diverse teaching strategies. We designed a course where we combined online teaching with independently conducted ecological data collections by students using a “citizen science” approach. The aim was to analyze the impact of urbanization on biota by comparing urban and rural grasslands. Seventy-five students successfully conducted the data collections and the results provide evidence for prevailing negative effects of urbanization. Individual numbers of ground-dwelling invertebrates (−25%) and pollinating insects (−33%) were generally lower in urban sites. Moreover, animal and seed predation were reduced in urban grasslands, indicating the potential of urbanization to alter ecosystem functions. Despite the general limitations of online teaching and citizen science approaches, outcomes of this course showed this combination can be a useful teaching strategy, which is why this approach could be used to more actively involve students in scientific research.

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Multi-domain probiotic consortium as an alternative to chemical remediation of oil spills at coral reefs and adjacent sites

Microbiome ◽

10.1186/s40168-021-01041-w ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Denise P. Silva ◽

Helena D. M. Villela ◽

Henrique F. Santos ◽

Gustavo A. S. Duarte ◽

José Roberto Ribeiro ◽

...

Keyword(s):

Microbial Community ◽

Coral Reefs ◽

Environmental Changes ◽

Oil Spills ◽

Anthropogenic Activities ◽

Oil Contamination ◽

Negative Effects ◽

Corexit 9500 ◽

Coral Health ◽

The Impact

Abstract Background Beginning in the last century, coral reefs have suffered the consequences of anthropogenic activities, including oil contamination. Chemical remediation methods, such as dispersants, can cause substantial harm to corals and reduce their resilience to stressors. To evaluate the impacts of oil contamination and find potential alternative solutions to chemical dispersants, we conducted a mesocosm experiment with the fire coral Millepora alcicornis, which is sensitive to environmental changes. We exposed M. alcicornis to a realistic oil-spill scenario in which we applied an innovative multi-domain bioremediator consortium (bacteria, filamentous fungi, and yeast) and a chemical dispersant (Corexit® 9500, one of the most widely used dispersants), to assess the effects on host health and host-associated microbial communities. Results The selected multi-domain microbial consortium helped to mitigate the impacts of the oil, substantially degrading the polycyclic aromatic and n-alkane fractions and maintaining the physiological integrity of the corals. Exposure to Corexit 9500 negatively impacted the host physiology and altered the coral-associated microbial community. After exposure, the abundances of certain bacterial genera such as Rugeria and Roseovarius increased, as previously reported in stressed or diseased corals. We also identified several bioindicators of Corexit 9500 in the microbiome. The impact of Corexit 9500 on the coral health and microbial community was far greater than oil alone, killing corals after only 4 days of exposure in the flow-through system. In the treatments with Corexit 9500, the action of the bioremediator consortium could not be observed directly because of the extreme toxicity of the dispersant to M. alcicornis and its associated microbiome. Conclusions Our results emphasize the importance of investigating the host-associated microbiome in order to detect and mitigate the effects of oil contamination on corals and the potential role of microbial mitigation and bioindicators as conservation tools. Chemical dispersants were far more damaging to corals and their associated microbiome than oil, and should not be used close to coral reefs. This study can aid in decision-making to minimize the negative effects of oil and dispersants on coral reefs.

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Experimental Evaluation of Compressor Blade Fouling

Volume 9: Oil and Gas Applications; Supercritical CO2 Power Cycles; Wind Energy ◽

10.1115/gt2016-56027 ◽

2016 ◽

Cited By ~ 3

Author(s):

Rainer Kurz ◽

Grant Musgrove ◽

Klaus Brun

Keyword(s):

Boundary Layer ◽

Gas Turbines ◽

Blade Surface ◽

Air Filtration ◽

Ambient Conditions ◽

Compressor Blades ◽

Performance Deterioration ◽

Quantitative Results ◽

The Impact ◽

Dust Retention

Fouling of compressor blades is an important mechanism leading to performance deterioration in gas turbines over time. Experimental and simulation data are available for the impact of specified amounts of fouling on performance, as well as the amount of foulants entering the engine for defined air filtration systems and ambient conditions. This study provides experimental data on the amount of foulants in the air that actually stick to a blade surface for different conditions of the blade surface. Quantitative results both indicate the amount of dust as well as the distribution of dust on the airfoil, for a dry airfoil, as well as airfoils that were wet from ingested water, as well as different types of oil. The retention patterns are correlated with the boundary layer shear stress. The tests show the higher dust retention from wet surfaces compared to dry surfaces. They also provide information about the behavior of the particles after they impact on the blade surface, showing that for a certain amount of wet film thickness, the shear forces actually wash the dust downstream, and off the airfoil. Further, the effect of particle agglomeration of particles to form larger clusters was observed, which would explain the disproportional impact of very small particles on boundary layer losses.

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Overfishing and nutrient pollution interact with temperature to disrupt coral reefs down to microbial scales

Nature Communications ◽

10.1038/ncomms11833 ◽

2016 ◽

Vol 7 (1) ◽

Cited By ~ 171

Author(s):

Jesse R. Zaneveld ◽

Deron E. Burkepile ◽

Andrew A. Shantz ◽

Catharine E. Pritchard ◽

Ryan McMinds ◽

...

Keyword(s):

Coral Reefs ◽

Nutrient Pollution

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Flow Assurance and Thermodynamic Challenges of operating CO2 Pipelines for variations in terrains and environments

10.2118/207572-ms ◽

2021 ◽

Author(s):

Terence George Wood ◽

Scott Campbell ◽

Nathan Smith

Keyword(s):

Process Equipment ◽

Fluid Composition ◽

Ambient Conditions ◽

Operating Modes ◽

Hydrocarbon Reservoir ◽

Compositional Approach ◽

Operational Life ◽

Geographical Distances ◽

Fluid Behaviour ◽

The Impact

Abstract The requirement for capturing and storing Carbon Dioxide will continue to grow in the next decade and a fundamental part of this is being able to transport the fluid over large geographical distances in numerous terrains and environments. The evolving nature of the fluid supply and the storage characteristics ensure the operation of the pipeline remains a challenge throughout its operational life. This paper will examine the impact of changes in the fluid composition, storage locations, ambient conditions and the various operating modes the pipeline will see throughout the lifecycle, highlight the technical design and operational challenges and finally give guidance on future developments. The thermodynamic behaviour of CO2 with and without impurities will be demonstrated utilising the fluid characterisation software, MultiflashTM. The fluid behaviour and hydraulic performance will be calculated over the expected operational envelope of the pipeline throughout field life, highlighting the benefits and constraints of using the single component module in OLGATM whilst comparing against a compositional approach when dealing with impurities. The paper will demonstrate through two case studies of varying nature including geographical environment, storage location (aquifer vs. abandoned hydrocarbon reservoir) and ambient conditions, the following issues: The impact of the storage type on the pipeline operations and how this will evolve with time; The environmental conditions and the impact these have on selection of process equipment and operational procedures (i.e. shutdown); and The impact the CO2 composition has on the design of the CO2 pipeline, and The paper will conclude with a set of guidelines for undertaking design analysis of CO2 pipelines for variations in fluid composition, storage locations and ambient conditions as well as some key operational strategies. This paper utilises the current state of the art tools and how these evolving tools are making this technically challenging area more mainstream.

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Interactions between invasive plants and heavy metal stresses: a review

Journal of Plant Ecology ◽

10.1093/jpe/rtab100 ◽

2021 ◽

Author(s):

Jian Li ◽

Zhanrui Leng ◽

Yueming Wu ◽

Yizhou Du ◽

Zhicong Dai ◽

...

Keyword(s):

Invasive Species ◽

Invasive Plants ◽

Native Plants ◽

Escape Behavior ◽

Negative Influence ◽

Plant Litter ◽

Global Changes ◽

Native Plant ◽

Anthropogenic Contamination ◽

The Impact

Abstract Global changes have altered the distribution pattern of the plant communities, including invasive species. Anthropogenic contamination may reduce native plant resistance to the invasive species. Thus, the focus of the current review is on the contaminant biogeochemical behavior among native plants, invasive species and the soil within the plant-soil ecosystem to improve our understanding of the interactions between invasive plants and environmental stressors. Our studies together with synthesis of the literature showed that a) the impacts of invasive species on environmental stress were heterogeneous, b) the size of the impact was variable, and c) the influence types were multidirectional even within the same impact type. However, invasive plants showed self-protective mechanisms when exposed to heavy metals (HMs) and provided either positive or negative influence on the bioavailability and toxicity of HMs. On the other hand, HMs may favor plant invasion due to the widespread higher tolerance of invasive plants to HMS together with the “escape behavior” of native plants when exposed to toxic HM pollution. However, there has been no consensus on whether elemental compositions of invasive plants are different from the natives in the polluted regions. A quantitative research comparing plant, litter and soil contaminant contents between native plants and the invaders in a global context is an indispensable research focus in the future.

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Benthic buffers and boosters of ocean acidification on coral reefs

Biogeosciences ◽

10.5194/bg-10-4897-2013 ◽

2013 ◽

Vol 10 (7) ◽

pp. 4897-4909 ◽

Cited By ~ 45

Author(s):

K. R. N. Anthony ◽

G. Diaz-Pulido ◽

N. Verlinden ◽

B. Tilbrook ◽

A. J. Andersson

Keyword(s):

Ocean Acidification ◽

Benthic Communities ◽

Time Of Day ◽

High Flow ◽

Net Community Production ◽

Reef Environment ◽

Saturation State ◽

Low Co2 ◽

Coral Reef Environment ◽

Community Production

Abstract. Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (NCP) and calcification (NCC). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in the seawater aragonite saturation state (Ωa). Results of flume studies using intact reef habitats (1.2 m by 0.4 m), showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350–450 μatm), macroalgae (Chnoospora implexa), turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h−1 – normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560–700 μatm) and high flow (35 compared to 8 cm s−1). In contrast, branching corals (Acropora aspera) increased Ωa by 0.25 h−1 at ambient CO2 (350–450 μatm) during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6–0.8 h−1) and exacerbated by acidification. Calcifying macroalgae (Halimeda spp.) raised Ωa by day (by around 0.13 h−1), but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from benthic communities with four different compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water-residence times in neighbouring areas dominated by turfs, macroalgae and carbonate sand.

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