Erratum: Near-shore Antarctic pH variability has implications for the design of ocean acidification experiments

Lydia Kapsenberg was omitted from the author list in the original version of this Article. This has been corrected in the PDF and HTML versions of the Article.

Kapsenberg L., Kelley A. L., Shaw E. C., Martz T. R. & Hofmann G. E., 2015. Near-shore Antarctic pH variability has implications for the design of ocean acidification experiments. Nature Scientific Reports 5:10497. Article.

Ancient fish evolved gills to survive acidic oceans

Fish gills evolved to balance pH, not breathe, suggests a new study. This goes against the traditional assumption that gills first evolved so fish could get more oxygen as they became bigger and more active, say researchers in a recent issue of Scientific Reports.

“When we think of the gill we automatically associate it with a human lung,” says co-author Dr Jodie Rummer, a fish physiologist at James Cook University in Townsville. “So the common thought has always been that perhaps the first reason a water breather needed to evolve a gill is to get oxygen.”

According to this so-called ‘oxygen hypothesis’, as organisms got fatter and more active, they needed more oxygen to sustain a higher metabolism.

A lot less oxygen dissolves in water than in air. While slow-moving, slim-lined fish could get away with absorbing oxygen through their thin skin, more active fish tended to be thicker-skinned (for protection) so they had to find more effective ways to get their oxygen.

The intricate folds of the gill provided the perfect solution. They had an immense surface area to allow oxygen to be absorbed into the fish’s bloodstream.

But Rummer and colleagues’ study of hagfish challenges the assumption that getting oxygen was the driver for fish developing gills.

Continue reading ‘Ancient fish evolved gills to survive acidic oceans’

Hagfish: Champions of CO2 tolerance question the origins of vertebrate gill function

The gill is widely accepted to have played a key role in the adaptive radiation of early vertebrates by supplanting the skin as the dominant site of gas exchange. However, in the most basal extant craniates, the hagfishes, gills play only a minor role in gas exchange. In contrast, we found hagfish gills to be associated with a tremendous capacity for acid-base regulation. Indeed, Pacific hagfish exposed acutely to severe sustained hypercarbia tolerated among the most severe blood acidoses ever reported (1.2 pH unit reduction) and subsequently exhibited the greatest degree of acid-base compensation ever observed in an aquatic chordate. This was accomplished through an unprecedented increase in plasma [HCO3−] (>75 mM) in exchange for [Cl−]. We thus propose that the first physiological function of the ancestral gill was acid-base regulation, and that the gill was later co-opted for its central role in gas exchange in more derived aquatic vertebrates.

Continue reading ‘Hagfish: Champions of CO2 tolerance question the origins of vertebrate gill function’

Latitudinal trends and drivers in the CO2–carbonic acid system of Papahānaumokuākea Marine National Monument

Emissions of anthropogenic carbon dioxide (CO2) to the atmosphere and the consequent effects of climate change and ocean acidification on coral reef ecosystems have motivated significant interest in describing and understanding the CO2–carbonic acid system of diverse coral reef environments. Although numerous studies have been successful in monitoring reef metabolism both in the field and in the laboratory, physical and biological forcings produce distinct conditions among environments. Due to the geographic isolation and associated difficulties with measuring marine carbon chemistry in waters of the Papahānaumokuākea Marine National Monument (PMNM), relatively few studies have described the CO2–carbonic acid system and carbonate saturation state gradients of these waters. Yet, PMNM remains one of the largest conservation areas in the world with extensive and diverse coral reef ecosystems that could offer valuable insight into our current and future understanding about regional and global impacts of ocean acidification. In order to provide a broad overview of latitudinal trends and features of the marine carbon system in PMNM waters, continuous measurements for surface seawater fugacity of CO2 (fCO2) and pH were collected during August 2011 and July 2012 cruises of the NOAA Ship Hi’ialakai. These measurements indicate that pH and fCO2 are three times more variable in nearshore monument waters relative to open ocean transect measurements. This variability can be observed up to 50 km away from the nearest reef and is likely the result of the direct and significant impact of coral reef metabolism on marine carbon chemistry around the islands and atolls. The relationship between total alkalinity and dissolved inorganic carbon is consistent with net calcification which creates an alkalinity sink throughout PMNM waters. Additionally, our measurements show clear latitudinal trends in fCO2, pH, and aragonite saturation state that are influenced by environmental forcings, including temperature, wind speed, and residence time of the water. Collectively, our results suggest that coral reefs located at the northernmost atolls of PMNM may be the most susceptible to the adverse impacts of climate change and ocean acidification.

Continue reading ‘Latitudinal trends and drivers in the CO2–carbonic acid system of Papahānaumokuākea Marine National Monument’

Study: world’s oceans facing irreversible damage without climate action

Unless ambitious action is taken to reduce carbon emissions the world’s oceans are facing dangerous and irreversible impact that could affect seafood supply, according to a new study.
The report, which has been published in the journal Science, evaluated and compared two scenarios under two potential carbon dioxide emission pathways over this century. While both scenarios carry high risks to vulnerable species, a business-as-usual scenario was projected to be “devastating” and have a high impact of widespread species moralities.

The author’s note that man-made climate change has led to profound alterations to the oceans, with greenhouse gas emissions leading to them warming up and becoming more acidic.

Lead author of the report, Jean-Pierre Gattuso, senior scientist at the Centre National de la Recherche Scientifique, France, said, “The oceans have been minimally considered at previous climate negotiations; our study provides compelling arguments for a radical change at COP21.”

Continue reading ‘Study: world’s oceans facing irreversible damage without climate action’

Climate change could drain global seafood supplies

Photo credit: M. Antonov, Getty Images

Photo credit: M. Antonov, Getty Images

Seafood lovers are set to see less shellfish, salmon and other fish on their dinner plates as climate change warms the oceans and makes them more acidic.

The findings from a series of studies out this week suggest rising greenhouse emissions from the burning of fossil fuels are adding stress to oceans that are already suffering from overfishing, pollution and destruction of coastal ecosystems like mangroves.

“The types of fish that we will have on our dinner table will be very different in the future,” said William Cheung, University of British Columbia associate professor and the co-director of the Nereus program, an international research team that put has put out a report on the state of the oceans. “Fisheries will be catching more warm-water species, with smaller size, and that will affect fish supply through our domestic and overseas fisheries as well as imports.”

Continue reading ‘Climate change could drain global seafood supplies’

Influence of CO2-induced seawater acidification on the development and lifetime reproduction of Tigriopus japonicus Mori, 1938

Ocean acidification is changing the carbonate system of the world’s oceans and has been driving all marine organisms to live in increasingly acidic environments. Tigriopus japonicus is an ideal standard test animal in sea water. In the present study, we investigated the influence of carbon dioxide (CO2)-induced seawater acidification on the development and lifetime reproduction of T. japonicus to accumulate basic data for assessing the potential impact of ocean acidification. The harpacticoid copepods were exposed in seawater equilibrated with CO2 and air to reach pH 8.0 (control), 7.7 (the predicted ocean pH by 2100), 7.3 (the predicted ocean pH by 2300) and 6.5 (an extreme condition relevant to industrial acid waste discharge or leakage from CO2 seabed storage). Survival was found to be unaffected following the 56 day exposure period. Significant retardation of development rates of the nauplius stage was observed at pH 6.5, while the development time of the copepodite stage was unaffected. Acidification did not affect the number of broods but it significantly reduced the hatching success of egg sacs at pH 6.5. Total production of nauplii over the lifetime of female copepods was significantly reduced at pH 7.3. Over successive broods, nauplius production was significantly affected by exposure time, pH and their interaction. Shedding of unhatched egg sacs by females mainly occurred in the late breeding stage at pH 7.3 and 6.5. Our results indicated that T. japonicus adults are tolerant to the ocean acidification conditions predicted for the year 2100, but the early development and reproductive capacity of females could be impaired by long-term exposure to more severe acidification conditions (pH 7.3 and 6.5). More long-term studies on a wider range of copepod species from different taxa and different marine habitats are urgently required to predict the fate of marine copepod communities in future oceans.

Continue reading ‘Influence of CO2-induced seawater acidification on the development and lifetime reproduction of Tigriopus japonicus Mori, 1938′

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