Seawater carbonate chemistry and larval growth response of the Portuguese oyster (Crassostrea angulata) in a laboratory experiment

Rising anthropogenic carbon dioxide (CO2) dissolving into coastal waters is decreasing the pH and carbonate ion concentration, thereby lowering the saturation state of calcium carbonate (CaCO3) minerals through a process named ocean acidification (OA). The unprecedented threats posed by such low pH on calcifying larvae of several edible oyster species have not yet been fully explored. Effects of low pH (7.9, 7.6, 7.4) on the early growth phase of Portuguese oyster (Crassostrea angulata) veliger larvae was examined at ambient salinity (34 ppt) and the low-salinity (27 ppt) treatment. Additionally, the combined effect of pH (8.1, 7.6), salinity (24 and 34 ppt) and temperature (24 °C and 30 °C) was examined using factorial experimental design. Surprisingly, the early growth phase from hatching to 5-day-old veliger stage showed high tolerance to pH 7.9 and pH 7.6 at both 34 ppt and 27 ppt. Larval shell area was significantly smaller at pH 7.4 only in low-salinity. In the 3-factor experiment, shell area was affected by salinity and the interaction between salinity and temperature but not by other combinations. Larvae produced the largest shell at the elevated temperature in low-salinity, regardless of pH. Thus the growth of the Portuguese oyster larvae appears to be robust to near-future pH level (> 7.6) when combined with projected elevated temperature and low-salinity in the coastal aquaculture zones of South China Sea.

Larval and post-larval stages of pacific oyster (Crassostrea gigas) are resistant to elevated CO2

Rising anthropogenic carbon dioxide (CO2) dissolving into coastal waters is decreasing the pH and carbonate ion concentration, thereby lowering the saturation state of calcium carbonate (CaCO3) minerals through a process named ocean acidification (OA). The unprecedented threats posed by such low pH on calcifying larvae of several edible oyster species have not yet been fully explored. Effects of low pH (7.9, 7.6, 7.4) on the early growth phase of Portuguese oyster (Crassostrea angulata) veliger larvae was examined at ambient salinity (34 ppt) and the low-salinity (27 ppt) treatment. Additionally, the combined effect of pH (8.1, 7.6), salinity (24 and 34 ppt) and temperature (24 °C and 30 °C) was examined using factorial experimental design. Surprisingly, the early growth phase from hatching to 5-day-old veliger stage showed high tolerance to pH 7.9 and pH 7.6 at both 34 ppt and 27 ppt. Larval shell area was significantly smaller at pH 7.4 only in low-salinity. In the 3-factor experiment, shell area was affected by salinity and the interaction between salinity and temperature but not by other combinations. Larvae produced the largest shell at the elevated temperature in low-salinity, regardless of pH. Thus the growth of the Portuguese oyster larvae appears to be robust to near-future pH level (> 7.6) when combined with projected elevated temperature and low-salinity in the coastal aquaculture zones of South China Sea.

Seawater carbonate chemistry and early development of the sea urchin Lytechinus variegatus in a laboratory experiment using artificial seawater

Land-based aquaculture facilities often utilize additional bicarbonate sources such as commercial sea salts that are designed to boost alkalinity in order to buffer seawater against reductions in pH. Despite these preventative measures, many facilities are likely to face occasional reductions in pH and corresponding reductions in carbonate saturation states due to the accumulation of metabolic waste products. We investigated the impact of reduced carbonate saturation states (Omega Ca, Omega Ar) on embryonic developmental rates, larval developmental rates, and echinoplutei skeletal morphometrics in the common edible sea urchin Lytechinus variegatus under high alkalinity conditions. Commercial artificial seawater was bubbled with a mixture of air and CO2 gas to reduce the carbonate saturation state. Rates of embryonic and larval development were significantly delayed in both the low and extreme low carbonate saturation state groups relative to the control at a given time. Although symmetry of overall skeletal body lengths was not affected, allometric relationships were significantly different between treatment groups. Larvae reared under ambient conditions had significantly greater postoral arm and overall body lengths relative to body lengths than larvae grown under extreme low carbonate saturation state conditions, indicating that extreme changes in the carbonate system affected not only developmental rates but also larval skeletal shape. Reduced rates of embryonic development and delayed and altered larval skeletal growth are likely to negatively impact larval culturing of L. variegatus in land-based, intensive culture situations where calcite and aragonite saturation states are lowered by the accumulation of metabolic waste products.

Seawater carbonate chemistry and calcification during incubation experiments with Mytilus edulis and Grassostrea gigas, 2006

Ocean acidification resulting from human emissions of carbon dioxide has already lowered and will further lower surface ocean pH. The consequent decrease in calcium carbonate saturation potentially threatens calcareous marine organisms. Here, we demonstrate that the calcification rates of the edible mussel (Mytilus edulis) and Pacific oyster (Crassostrea gigas) decline linearly with increasing pCO2. Mussel and oyster calcification may decrease by 25 and 10%, respectively, by the end of the century, following the IPCC IS92a scenario (?740 ppmv in 2100). Moreover, mussels dissolve at pCO2 values exceeding a threshold value of ?1800 ppmv. As these two species are important ecosystem engineers in coastal ecosystems and represent a large part of worldwide aquaculture production, the predicted decrease of calcification in response to ocean acidification will probably have an impact on coastal biodiversity and ecosystem functioning as well as potentially lead to significant economic loss.

Data compilation on the biological response to ocean acidification: environmental and experimental context of data sets and related literature

The exponential growth of studies on the biological response to ocean acidification over the last few decades has generated a large amount of data. To facilitate data comparison, a data compilation hosted at the data publisher PANGAEA was initiated in 2008 and is updated on a regular basis (doi:10.1594/PANGAEA.149999). By January 2015, a total of 581 data sets (over 4 000 000 data points) from 539 papers had been archived. Here we present the developments of this data compilation five years since its first description by Nisumaa et al. (2010). Most of study sites from which data archived are still in the Northern Hemisphere and the number of archived data from studies from the Southern Hemisphere and polar oceans are still relatively low. Data from 60 studies that investigated the response of a mix of organisms or natural communities were all added after 2010, indicating a welcomed shift from the study of individual organisms to communities and ecosystems. The initial imbalance of considerably more data archived on calcification and primary production than on other processes has improved. There is also a clear tendency towards more data archived from multifactorial studies after 2010. For easier and more effective access to ocean acidification data, the ocean acidification community is strongly encouraged to contribute to the data archiving effort, and help develop standard vocabularies describing the variables and define best practices for archiving ocean acidification data.

Morphometry and biomass of the cultured mangrove oyster Crassostrea rhizophorae at the Urindeua river, eastern Amazonia, northern Brazil

The malacocultura, particularly oyster farming, appears on the world stage as one of the most viable alternatives to fishing decline and supply of fresh product. In Brazil, the development of mollusc cultivationis through the genus oyster cultivation Crassostrea, among them Crassostrea rhizophorae (Guilding, 1828), known for oyster-the-swamp, one of the main species of farmed bivalves in the state of Pará. This so it aimed to characterize the biomorphometrics relations, estimate the Shape Stabilization Index (IEF) of the shell and the yield of edible meat C. rhizophorae grown in an Amazonian coast, state of Pará, northern Brazil. When all is sampled 1,028 individuals, in April 2016, measuring the external morphometric measures (length, width and height) and total and visceral biomass. The results obtained are C. rhizophorae with (1) excellent biomorphometrics relationships among both external measures, the measures of the shell and biomass generating equations that satisfy morphometric pet species, (2) yield of edible meat 15% of the total biomass and variation in the shell along its development to adulthood, with a tendency to stabilize the reach 60mm in length.