Archive for July, 2016

Autonomous 13C measurements in the North Atlantic – a novel approach for identifying patterns and driving factors of the upper ocean carbon cycle

The North Atlantic Ocean plays a major role in climate change not least due to its importance in CO2 uptake and thus natural carbon sequestration. The CO2 concentration in its surface waters, which determines the ocean’s CO2 sink/source function, varies on seasonal and interannual timescales and is mainly driven by air-sea gas exchange and biological production/respiration. However, the quantification of these processes is still afflicted with a high degree of uncertainty. In this thesis, a cavity ringdown spectrometer (G2131-i, Picarro, USA), which is able to measure the CO2 mole fraction and it’s stable carbon isotope composition, was installed on a VOS line that regularly sails across the subpolar North Atlantic between North America and Europe. From summer 2012 to the end of 2014, two and a half years of d13C(CO2) underway data was obtained along with continuous measurements of temperature, salinity and fCO2. Combined with a discrete sampling program (consisting of DIC, TA, nutrients, Chl a, POM, DOC, d13C(POC) and d15N(PON) samples), the dynamics of the upper North Atlantic Ocean were studied. This analysis comprises interannual variations of fCO2 and d13C(CO2), relative changes of nutrient concentration in comparison with C:N ratios of suspended particle matter, biologically and mixing driven variability in DIC and d13C(DIC) and the fractionation between dissolved CO2 and particulate matter. Based on the variations in DIC, fCO2, DIC, fCO2, d13C(DIC), nitrate, phosphate and silicate, the respective change rates and overall inventory changes due to air-sea gas exchange, net community production and convective mixing were calculated utilizing a box model.

Continue reading ‘Autonomous 13C measurements in the North Atlantic – a novel approach for identifying patterns and driving factors of the upper ocean carbon cycle’

Ocean acidification alters fish reproductive behaviour

A new study conducted close to volcanic vents off the coast of Southern Italy reveals that ocean acidification could have a major impact on the reproductive behaviour of fish living in affected waters.

In particular, the research demonstrated marked reproductive differences in species of ocellated wrasse (Symphodus ocellatus).

The study scientists stress that key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO2 concentrations but that dominant males did experience significantly lower rates of pair spawning at elevated CO2 levels, but a sizeable increase in their mating success.

Scientists say that while previous research has shown fish exhibit impaired sensory function and altered behaviour at high levels of ocean acidification, this study – conducted using cameras at nest sites followed by paternity tests in laboratories – provides the first evidence of the effects of ocean acidification on the reproductive behaviour of fish in the wild.

“Given the importance of fish for food security and ecosystem stability, these results highlight the need for further targeted research into the effects of rising CO2 levels on their reproduction,” pointed out professor Marco Milazzo, of the University of Palermo.

Continue reading ‘Ocean acidification alters fish reproductive behaviour’

Increasing ocean acidity could impact fish spawning

A new study suggests that the increasing acidification of the oceans is likely to interfere with the ability of fish to reproduce.

Researchers found that elevated levels of CO2, which make the waters more acidic, saw significantly lower levels of spawning. However, other mating behaviours of the same species were unaffected by the souring of the oceans. The scientists say the changes are “subtle but ecologically important”.

The study examined the complicated mating behaviours of ocellated wrasse, a common Mediterranean fish. There are three different types of male who compete to father the offspring of this species.

Sneaky males

Dominant males build nests and provide defence, while satellite males aid the dominants in return for a share of the eggs. “Sneaker” males hover around the nests and try and take advantage when the dominants are distracted.

Continue reading ‘Increasing ocean acidity could impact fish spawning’

First evidence of ocean acidification’s impact on reproductive behavior in wild fish (text & video)

Ocean acidification could have a major impact on the reproductive behaviour of fish living in affected waters, a new study shows.

Research conducted close to volcanic vents off the coast of Southern Italy demonstrated marked reproductive differences in species of ocellated wrasse (Symphodus ocellatus).

Key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO2 concentrations. Dominant males, however, did experience significantly lower rates of pair spawning at elevated CO2 levels, but a sizeable increase in their mating success.

Scientists say that while previous research has shown fish exhibit impaired sensory function and altered behaviour at high levels of ocean acidification, this study – conducted using cameras at nest sites followed by paternity tests in laboratories – provides the first evidence of the effects of ocean acidification on the reproductive behaviour of fish in the wild.

Professor Marco Milazzo, of the University of Palermo, said: “Given the importance of fish for food security and ecosystem stability, these results highlight the need for further targeted research into the effects of rising CO2 levels on their reproduction.”

Continue reading ‘First evidence of ocean acidification’s impact on reproductive behavior in wild fish (text & video)’

Ocean acidification affects fish spawning but not paternity at CO2 seeps

Fish exhibit impaired sensory function and altered behaviour at levels of ocean acidification expected to occur owing to anthropogenic carbon dioxide emissions during this century. We provide the first evidence of the effects of ocean acidification on reproductive behaviour of fish in the wild. Satellite and sneaker male ocellated wrasse (Symphodus ocellatus) compete to fertilize eggs guarded by dominant nesting males. Key mating behaviours such as dominant male courtship and nest defence did not differ between sites with ambient versus elevated CO2 concentrations. Dominant males did, however, experience significantly lower rates of pair spawning at elevated CO2 levels. Despite the higher risk of sperm competition found at elevated CO2, we also found a trend of lower satellite and sneaker male paternity at elevated CO2. Given the importance of fish for food security and ecosystem stability, this study highlights the need for targeted research into the effects of rising CO2 levels on patterns of reproduction in wild fish.

Continue reading ‘Ocean acidification affects fish spawning but not paternity at CO2 seeps’

Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO2 concentrations

Diel or seasonal fluctuations in seawater carbonate chemistry are common in coastal waters, while in the open ocean carbonate chemistry is much less variable. In both of these environments, ongoing ocean acidification is being superimposed on the natural carbonate buffer system to influence the physiology of phytoplankton. Here, we show that a coastal Thalassiosira weissflogii isolate and an oceanic diatom, Thalassiosira oceanica, respond differentially to diurnal fluctuating carbonate chemistry in current and ocean acidification (OA) scenarios. A fluctuating carbonate chemistry regime showed positive or negligible effects on physiological performance of the coastal species. In contrast, the oceanic species was significantly negatively affected, with higher respiration than cells grown under the corresponding steady regime. The fluctuating regime reduced photosynthetic oxygen evolution rates of T. oceanica under ambient CO2 concentration, while in the OA scenario, the fluctuating regime depressed its growth rate, chlorophyll a content, and elemental production rates. These contrasting physiological performances of coastal and oceanic diatoms indicate that they differ in the ability to cope with dynamic pCO2. We propose that, in addition to the ability to cope with light, nutrient, and predation pressure, the ability to acclimate to dynamic carbonate chemistry may act as one determinant of the spatial distribution of diatom species. Habitat-relevant diurnal changes in seawater carbonate chemistry can interact with OA to differentially affect diatoms in coastal and pelagic waters.

Continue reading ‘Physiological responses of coastal and oceanic diatoms to diurnal fluctuations in seawater carbonate chemistry under two CO2 concentrations’

Response of coral reefs to global warming

The atmospheric CO2 crossed over 400 ppm and we must prepare for a “+2 °C world” during this century. Coral reefs are directly related to each scenario of global warming: increase in CO2 results in ocean acidification and suppresses calcification, rise in sea surface temperature leads to severe bleaching, and sea level rise causes submergence of coral reefs and atoll islands. They are the most sensitive ecosystem and act as an early warning system to examine and predict response of ecosystem to the global warming. Records of bleaching events and SST for the last 17 years in the northwest Pacific show that 2 °C SST rise would induce severe bleaching of coral reefs. Reduction of ocean surface water pH by 0.3 would cause shift from hard coral to non-calcifying macroalgae or soft coral populations in coral reefs. Submergence of coral reefs by sea level rise of up to one meter results in a loss of their breakwater function and in atoll islands submergence of national land. “+2 °C world” is the threshold to maintain coral reefs. Factors of global warming and responses of coral reefs are coupled to form feedback loops, which enhance or stabilize the changes within a system.

Continue reading ‘Response of coral reefs to global warming’

Effects of potential future CO2 levels in seawater on emerging behaviour and respiration of Manila clams, Venerupis philippinarum

High atmospheric CO2 dissolves into the surface of the ocean and lowers the pH of seawater and is thus expected to pose a potential threat to various marine organisms. We investigated the physiological and behavioural responses of adult Manila clams, Venerupis philippinarum (n = 96, shell length 25.32 ± 1.66mm and total wet weight 3.10 ± 0.54 g), to three levels (400, 700, and 900 μatm) of CO2 partial pressure (pCO2) for 48 days. There were no significant differences in mortality, growth, respiration rate, or emergence from the sediment between the three levels, indicating that near future atmospheric levels of CO2 do not seem to have a serious effect on the physiology and behaviour of adult Manila clams. However, Manila clams could be exposed to notably higher pCO2 and lower pH levels at local conditions due to the other issues, including eutrophication. Thus, the younger clams (n = 240, shell length 16.71 ± 0.96mm and total wet weight 0.70 ± 0.13 g) were exposed to pCO2 levels of 900 μatm (pH 7.8) and higher, such as 1300 and 2300 μatm (pH 7.7 and 7.5, respectively), for 39 days. Although mortality and growth were not significantly different between treatments, the emergence rates at the two higher pCO2 levels were higher than that at the lowest level during the last 10 days of the experiment. The oxygen consumption rate (OCR) was reduced after 39 days of exposure to 2300 μatm of pCO2. The increase in emerging behaviour and the decrease in the rate of oxygen consumption indicated worse physiological conditions of the clams; the population may be negatively influenced due to worse conditions or increased probability of predation.

Continue reading ‘Effects of potential future CO2 levels in seawater on emerging behaviour and respiration of Manila clams, Venerupis philippinarum’

Ocean acidification monitoring public-private partnership launched in Southern Africa

Office of the Spokesperson, Washington, DC, July 25, 2016

The U.S. Department of State has partnered with the Ocean Foundation, the Heising-Simons Foundation, Schmidt Marine Technology Partners, and the XPRIZE Foundation to launch a public-private partnership, the “OceAn pH Research Integration and Collaboration in Africa (ApHRICA)” project, to advance ocean acidification monitoring in Mauritius, Mozambique, Seychelles, and South Africa. ApHRICA’s regional capacity building workshop will be held July 26-30, 2016, in Mauritius and will welcome ocean scientists from African countries to learn how to operate new ocean acidification monitoring technology and will facilitate connections to global efforts such as the Global Ocean Acidification Observing Network (GOA-ON).

ApHRICA was announced at the 2015 Our Ocean Conference in Chile. The program seeks to increase worldwide coverage of the GOA-ON and train monitors and managers to better understand the impacts of ocean acidification, especially in Africa, where there is limited monitoring.

Continue reading ‘Ocean acidification monitoring public-private partnership launched in Southern Africa’

Scaling positive impact – ‘ApHRICA’ to revolutionize understanding of ocean acidification

This week kicks off a groundbreaking workshop and pilot project to install cutting-edge ocean sensors in Mauritius, Mozambique, the Seychelles and South Africa to study ocean acidification in East Africa for the first time. The project is actually called “OceAn pH Research Integration and Collaboration in Africa – ApHRICA“. Workshop speakers include the White House Science Envoy for Ocean, Dr. Jane Lubchenco, Dr. Roshan Ramessur at the University of Mauritius, and ocean sensor trainers and scientists Dr. Andrew Dickson of UCSD, Dr. Sam Dupont of University of Gothenburg, and James Beck, CEO of Sunburst Sensors.

ApHRICA has been years in the making, starting with developing ocean pH sensor tools, engaging leading experts, and raising the funds to bring passionate people and new technologies together to take action, and fill much-needed ocean data gaps. Last July, XPRIZE awarded the $2 million Wendy Schmidt Ocean Health XPRIZE, a prize competition for developing breakthrough ocean pH sensors to improve understanding of ocean acidification. One year later, the winning team Sunburst Sensors, a small company in Missoula, Montana, is providing their ‘iSAMI’ ocean pH sensor for this project. The iSAMI was chosen due to its unprecedented affordability, accuracy and ease of use.

2016-07-26-1469550770-1532426-wsohxp_july_2016_blog_1-thumb

GOA-ON map

Continue reading ‘Scaling positive impact – ‘ApHRICA’ to revolutionize understanding of ocean acidification’


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