Posts Tagged 'methods'

Equipping smart coasts with marine water quality IoT sensors

Highlights

• This micro-manuscript describes a university/industry collaboration to study water quality at a shellfish hatchery.

• We designed a real-time communications system including hardware, firmware, and web visualization/analysis software.

• A dashboard is located at sccoos.org/ocean-acidification/ and code at github.com/SUPScientist/Equipping-Smart-Coasts.

Abstract

Ocean acidification, the decrease in seawater pH as a result of increasing carbon dioxide, has been shown to be an important driver of oyster mortality in West Coast shellfisheries [1]. Yet carbon chemistry is only sparsely measured, especially relative to its high variability in coastal ecosystems, due to the complexity and cost of appropriate sensors and their maintenance. Worse, data are rarely communicated in real time to water quality or aquacultural managers. In the Agua Hedionda Lagoon (AHL) in Carlsbad, CA, researchers from Scripps Institution of Oceanography and industry representatives from the Carlsbad Aquafarm have come together through a NOAA-facilitated project to alleviate this data shortage using a combination of cutting-edge research technology alongside off-the-shelf and easy-to-implement IoT communications packages.

Continue reading ‘Equipping smart coasts with marine water quality IoT sensors’

Use of high-frequency noninvasive electromagnetic biosensors to detect ocean acidification effects on shellfish behavior

Although ocean acidification studies related to marine animal behavior have increased in recent years, the behavioral effects of ocean acidification on shellfish are relatively understudied, even though marine shellfish exhibit a wealth of behaviors that can modify organismal interactions and biological community functioning. Furthermore, detecting acute behavioral changes may provide a biological indicator of ecosystem stress and/or an early warning system for aquaculture operations. This article highlights a new and emerging technology—high-frequency noninvasive (HFNI) electromagnetic biosensors—that can be used to document acute and long-term effects of elevated CO2 on the valve-gaping behavior of marine bivalves. An overview of the technology is presented, and the current and potential uses of these biosensors in ocean acidification research are highlighted, along with current limitations and next steps. Although a handful of studies have used these biosensors to test for effects of acidification on bivalve valve-gaping behavior, their potential for testing critical and novel hypotheses regarding ocean acidification effects in a broader range of shellfish taxa is currently underused. Ultimately, this article provides a basis for expanding ocean acidification research on shellfish behavior through the use of HFNI electromagnetic biosensors.

Continue reading ‘Use of high-frequency noninvasive electromagnetic biosensors to detect ocean acidification effects on shellfish behavior’

Coral reef pH altered in situ

A Free Ocean Carbon Enrichment experiment that manipulates seawater pH on a coral reef flat shows that the level of ocean acidification at which net dissolution of corals occurs may arrive much sooner than expected.

Coral reefs are at the forefront of public perception about the impacts of climate change in the world’s oceans. Along with warming, which induces coral bleaching and mortality, the decreasing pH of seawater due to ocean acidification is expected to have dire consequences for coral reefs as we know them, in part through lower availability of carbonate ions (CO32–), which are used in combination with calcium ions (Ca2+) by corals for skeletal growth. Writing in Nature Ecology & Evolution, Kline et al. report their use of Free Ocean Carbon Enrichment (FOCE) technology to investigate coral calcification and dissolution in an in situ ocean acidification experiment on a coral reef flat on the Great Barrier Reef, over a period of 200 d. Although their study is of a single coral species in a single location, the realistic setting makes this study particularly relevant.

Continue reading ‘Coral reef pH altered in situ’

The development and validation of a profiling glider deep ISFET-based pH sensor for high resolution observations of coastal and ocean acidification

Coastal and ocean acidification can alter ocean biogeochemistry, with ecological consequences that may result in economic and cultural losses. Yet few time series and high resolution spatial and temporal measurements exist to track the existence and movement of water low in pH and/or carbonate saturation. Past acidification monitoring efforts have either low spatial resolution (mooring) or high cost and low temporal and spatial resolution (research cruises). We developed the first integrated glider platform and sensor system for sampling pH throughout the water column of the coastal ocean. A deep ISFET (Ion Sensitive Field Effect Transistor)-based pH sensor system was modified and integrated into a Slocum glider, tank tested in natural seawater to determine sensor conditioning time under different scenarios, and validated in situ during deployments in the U.S. Northeast Shelf (NES). Comparative results between glider pH and pH measured spectrophotometrically from discrete seawater samples indicate that the glider pH sensor is capable of accuracy of 0.011 pH units or better for several weeks throughout the water column in the coastal ocean, with a precision of 0.005 pH units or better. Furthermore, simultaneous measurements from multiple sensors on the same glider enabled salinity-based estimates of total alkalinity (AT) and aragonite saturation state (ΩArag). During the Spring 2018 Mid-Atlantic deployment, glider pH and derived AT/ΩArag data along the cross-shelf transect revealed higher pH and ΩArag associated with the depth of chlorophyll and oxygen maxima and a warmer, saltier water mass. Lowest pH and ΩArag occurred in bottom waters of the middle shelf and slope, and nearshore following a period of heavy precipitation. Biofouling was revealed to be the primary limitation of this sensor during a summer deployment, whereby offsets in pH and AT increased dramatically. Advances in anti-fouling coatings and the ability to routinely clean and swap out sensors can address this challenge. The data presented here demonstrate the ability for gliders to routinely provide high resolution water column data on regional scales that can be applied to acidification monitoring efforts in other coastal regions.

Continue reading ‘The development and validation of a profiling glider deep ISFET-based pH sensor for high resolution observations of coastal and ocean acidification’

A photonic pH sensor based on photothermal spectroscopy

Although the determination of pH is a standard laboratory measurement, new techniques capable of measuring pH are being developed to facilitate modern technological advances. Bio-industrial processing, tissue engineering, and intracellular environments impose unique measurement requirements on probes of pH. We describe a fiber optic-based platform, which measures the heat released by chromophores upon absorption of light. The optical fibers feature fiber Bragg gratings (FBG) whose Bragg peak redshifts with increasing temperature. Using anthocyanins (pH-sensitive chromophores found in many plants), we are able to correlate visible light absorption by a solution of anthocyanins to heat released and changes in FBG signal over a pH range of 2.5–10. We tested the ability of this platform to act as a sensor coating the fiber within a layer of crosslinked polyethylene glycol diacrylate (PEG-DA). Incorporating the anthocyanins into the PEG, we find that the signal magnitude increases over the observed signal at the same pH in solution. Our results indicate that this platform is viable for assessing pH in biological samples and point at ways to optimize performance.

Continue reading ‘A photonic pH sensor based on photothermal spectroscopy’

Intercomparison of four methods to estimate coral calcification under various environmental conditions

Coral reefs are constructed by calcifiers that precipitate calcium carbonate to build their shells or skeletons through the process of calcification. Accurately assessing coral calcification rates is crucial to determine the health of these ecosystems and their response to major environmental changes such as ocean warming and acidification. Several approaches have been used to assess rates of coral calcification but there is a real need to compare these approaches in order to ascertain that high quality and intercomparable results can be produced. Here, we assessed four methods (total alkalinity anomaly, calcium anomaly, 45Ca incorporation and 13C incorporation) to determine coral calcification of the reef-building coral Stylophora pistillata. Given the importance of environmental conditions on this process, the study was performed under two pH (ambient and low level) and two light (light and dark) conditions. Under all conditions, calcification rates estimated using the alkalinity and calcium anomaly techniques as well as 45Ca incorporation were highly correlated. Such a strong correlation between the alkalinity anomaly and 45Ca incorporation techniques has not been observed in previous studies and most probably results from improvements described in the present paper. The only method which provided calcification rates significantly different from the other three techniques was 13C incorporation. Calcification rates based on this method were consistently higher than those measured using the other techniques. Although reasons for these discrepancies remain unclear, the use of this technique for assessing calcification rates in corals is not recommended without further investigations.

Continue reading ‘Intercomparison of four methods to estimate coral calcification under various environmental conditions’

New methods for imaging and quantifying dissolution of pteropods to monitor the impacts of ocean acidification

Large-scale changes in climate and ocean ecosystems demand innovative and cost-effective ways to track changes in the marine environment and its living resources. During the past decade, ocean acidification has become recognized as a major threat to the biodiversity of marine ecosystems during the 21st century. However, an important constraint on modern ocean acidification research is the lack of accessibility to effective imaging techniques, as well as accurate analytical methods. Here, we compare several different microscopic techniques to evaluate the relative merits of each. Additionally, a new dissolution quantification method is developed that more completely assesses damage over an entire shell. These findings can help expand the toolbox for scientists engaged in studying the impacts of ocean acidification on marine invertebrates and enable more researchers to participate in this vital field.

Continue reading ‘New methods for imaging and quantifying dissolution of pteropods to monitor the impacts of ocean acidification’


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Ocean acidification in the IPCC AR5 WG II

OUP book