Climate experts say ocean acidification is hurting the Belize Barrier Reef

The Belize Barrier Reef is the longest in the Western Hemisphere, and the second-longest in the world. It is also on the frontlines of climate change, with new observed impacts arising from increase ocean acidity.

BELMOPAN, Belize, October 27, 2014 (AMG) — The effects of climate change are weighing heavily on the fishing and tourism industries in Belize, according to experts at the Caribbean Community Climate Change Centre (CCCCC).

Citing increasingly-acidic oceans, the CCCCC has observed declines in marine populations, with a knock-on effect on exports and foreign exchange earnings. The reality is made worse by illegal overfishing and premature harvesting of conch and lobster during the country’s enforced closed seasons.

Ocean acidification occurs when greenhouse gases (GHGs) in the atmosphere are trapped and stored in the ocean as carbonic acid. Calcium in the shells of crustaceans interacts with the carbonic acid forming calcium carbonate, which dissolves crustaceans’ shells – affecting their ability to survive. Coral bleaching, which occurs as a result of warm ocean temperatures, also affects the health of the reefs where much of the marine population lives.

Continue reading ‘Climate experts say ocean acidification is hurting the Belize Barrier Reef’

Effects of ocean acidification on development of Alaskan crab larvae

The oceans absorb a large proportion of the carbon dioxide gas (CO2) emitted into the atmosphere. This CO2 changes the chemistry of seawater to make it more acidic, a phenomenon termed ocean acidification. Ocean acidification can have negative impacts on marine fauna, especially during early life stages, presenting a risk to ecosystems and fisheries. This research tested the effects of ocean acidification on the larval development of three crab species in Alaska: Tanner crab (Chionoecetes bairdi), rock crab (Glebocarcinus oregonensis), and Dungeness crab (Metacarcinus magister). Experiments were undertaken to assess the effects of exposure to low-pH conditions (decrease of up to 0.6 pH units from current levels, range of pH ~8.1 to 7.5) on survival, growth (morphometrics and mass), and carapace mineral composition of larval Tanner, rock, and Dungeness crabs. Results showed a decrease in survival as well as a small but nonsignificant decrease in size of Tanner crabs. There was a small and complex effect of pH on survival of Dungeness crabs. Rock crabs raised in low-pH conditions (pH 7.5) had higher individual biomass than those raised in ambient conditions (pH 8.1). There was no significant impact of pH on mineralization of any species. Therefore, low pH had a negative effect on development of Tanner crabs, a small effect on Dungeness larval survival and no discernible negative effect on rock crab larvae. Differences in response to ocean acidification may be related to pre-adaptation to variable pH conditions through lifestyle such that species that live in deeper, more stable waters (e.g., Tanner crab) are more vulnerable than species living in shallower, more variable waters (e.g., rock and Dungeness crabs). These observations suggest that ocean acidification will have negative impacts on Tanner and Dungeness crab larval survival with potential implications for recruitment to the adult population and consequently, for their fisheries.

Continue reading ‘Effects of ocean acidification on development of Alaskan crab larvae’

Ocean acidification in the aftermath of the Marinoan glaciation

Boron isotope patterns preserved in cap carbonates deposited in the aftermath of the younger Cryogenian (Marinoan, ca. 635 Ma) glaciation confirm a temporary ocean acidification event on the continental margin of the southern Congo craton, Namibia. To test the significance of this acidification event and reconstruct Earth’s global seawater pH states at the Cryogenian-Ediacaran transition, we present a new boron isotope data set recorded in cap carbonates deposited on the Yangtze Platform in south China and on the Karatau microcontinent in Kazakhstan. Our compiled δ11B data reveal similar ocean pH patterns for all investigated cratons and confirm the presence of a global and synchronous ocean acidification event during the Marinoan deglacial period, compatible with elevated postglacial pCO2 concentrations. Differences in the details of the ocean acidification event point to regional distinctions in the buffering capacity of Ediacaran seawater.

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Comparative responses of two dominant Antarctic phytoplankton taxa to interactions between ocean acidification, warming, irradiance, and iron availability

We investigated the responses of the ecologically dominant Antarctic phytoplankton species Phaeocystis antarctica (a prymnesiophyte) and Fragilariopsis cylindrus (a diatom) to a clustered matrix of three global change variables (CO2, mixed-layer depth, and temperature) under both iron (Fe)-replete and Fe-limited conditions based roughly on the Intergovernmental Panel on Climate Change (IPCC) A2 scenario: (1) Current conditions, 39 Pa (380 ppmv) CO2, 50 µmol photons m−2 s−1 light, and 2°C; (2) Year 2060, 61 Pa (600 ppmv) CO2, 100 µmol photons m−2 s−1 light, and 4°C; (3) Year 2100, 81 Pa (800 ppmv) CO2, 150 µmol photons m−2 s−1 light, and 6°C. The combined interactive effects of these global change variables and changing Fe availability on growth, primary production, and cell morphology are species specific. A competition experiment suggested that future conditions could lead to a shift away from P. antarctica and toward diatoms such as F. cylindrus. Along with decreases in diatom cell size and shifts from prymnesiophyte colonies to single cells under the future scenario, this could potentially lead to decreased carbon export to the deep ocean. Fe : C uptake ratios of both species increased under future conditions, suggesting phytoplankton of the Southern Ocean will increase their Fe requirements relative to carbon fixation. The interactive effects of Fe, light, CO2, and temperature on Antarctic phytoplankton need to be considered when predicting the future responses of biology and biogeochemistry in this region.

Continue reading ‘Comparative responses of two dominant Antarctic phytoplankton taxa to interactions between ocean acidification, warming, irradiance, and iron availability’

Deep-water boost for a community exposed to ocean change: Mesocosm experiment on the effects of ocean acidification at its summit

29. October, 2014/ Kiel, Taliarte. In a long-term field study led by GEOMAR Helmholtz Centre for Ocean Research Kiel, an international team of scientists investigates the effects of ocean acidification on pelagic ecosystems in the subtropical Atlantic. The field experiment with the KOSMOS mesocosms off Gran Canary now culminates in the simulation of deep-water upwelling – an event that can boost productivity in these nutrient-starving waters. For this purpose, the researchers developed an 80,000 litres deep-water collector.
How do communities in the nutrient-poor, so-called oligotrophic open ocean react, if the seawater gradually acidifies due to the uptake of human-induced carbon dioxide (CO2)? How are elemental fluxes and interactions in the food web affected, if these high-CO2 exposed communities experience an influx of nutrient-rich deep-water? In a large-scale field experiment, 53 scientists from Germany, Spain, France, Great Britain and the United States are investigating how ocean acidification influences important functions in an ecosystem representative for two-thirds of the world’s oceans. For this experiment, the two German research networks BIOACID (Biological Impacts of Ocean Acidification) and SOPRAN (Surface Ocean Processes in the Anthropocene) cooperate with the Spanish research station Plataforma Oceánica de Canarias (PLOCAN) and the University of Las Palmas de Gran Canaria (ULPGC).

Continue reading ‘Deep-water boost for a community exposed to ocean change: Mesocosm experiment on the effects of ocean acidification at its summit’

Spatio-temporal variability of polychaete colonization at volcanic CO2 vents indicates high tolerance to ocean acidification

Ocean acidification is predicted to have negative effects on marine biota, resulting in the loss of biodiversity and changes in marine ecosystem structure and function. However, some species and life stages may be capable of thriving in low pH conditions, either due to their natural ability to tolerate stressful low pH–high pCO2 conditions and/or alteration of species interactions caused by changes in pH profiles, or due to evolutionary trade-offs. A better understanding of which species may be capable of tolerating ocean acidification can guide future research into the mechanisms for physiological and ecological resilience to future carbon dioxide (CO2) conditions. We investigated the colonization of selected polychaete species along a pH gradient originating from shallow, coastal volcanic CO2 vents (Ischia, Italy). Colonization was quantified by exposing artificial invertebrate collectors attached to the substratum for 30 days during different periods of the year (late spring, fall and late winter). Three species, Amphiglena mediterranea, Platynereis dumerilii and Syllis prolifera, were present and abundant along the gradient throughout the year. All three species were significantly more abundant in the most acidified areas, confirming their high tolerance and capacity to cope with very low pH. Abundances of all three species were compared to data previously collected via collectors suspended in the water column. More individuals were found in the collectors attached to the substratum, suggesting that abundances may have previously been underestimated. This is likely due to the close proximity of these collectors with the natural rocky substratum. All three species exhibited similar temporal variability, consistent with their life cycle and reproductive biology. Our results demonstrate high tolerance of the species for low and variable pH and corroborate their use as robust models to explore the capacity to cope with low pH–high pCO2 conditions, both in the natural vent systems and in the laboratory.

Continue reading ‘Spatio-temporal variability of polychaete colonization at volcanic CO2 vents indicates high tolerance to ocean acidification’

Benthic coral reef calcium carbonate dissolution in an acidifying ocean

Changes in CaCO3 dissolution due to ocean acidification are potentially more important than changes in calcification to the future accretion and survival of coral reef ecosystems. As most CaCO3 in coral reefs is stored in old permeable sediments, increasing sediment dissolution due to ocean acidification will result in reef loss even if calcification remains unchanged. Previous studies indicate that CaCO3 dissolution could be more sensitive to ocean acidification than calcification by reef organisms. Observed changes in net ecosystem calcification owing to ocean acidification could therefore be due mainly to increased dissolution rather than decreased calcification. In addition, biologically mediated calcification could potentially adapt, at least partially, to future ocean acidification, while dissolution, which is mostly a geochemical response to changes in seawater chemistry, will not adapt. Here, we review the current knowledge of shallow-water CaCO3 dissolution and demonstrate that dissolution in the context of ocean acidification has been largely overlooked compared with calcification.

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