Archive for July, 2010

Insights into shell deposition in the Antarctic bivalve Laternula elliptica: gene discovery in the mantle transcriptome using 454 pyrosequencing

Background
The Antarctic clam, Laternula elliptica, is an infaunal stenothermal bivalve mollusc with a circumpolar distribution. It plays a significant role in bentho-pelagic coupling and hence has been proposed as a sentinel species for climate change monitoring. Previous studies have shown that this mollusc displays a high level of plasticity with regard to shell deposition and damage repair against a background of genetic homogeneity. The Southern Ocean has amongst the lowest present-day CaCO3 saturation rate of any ocean region, and is predicted to be among the first to become undersaturated under current ocean acidification scenarios. Hence, this species presents as an ideal candidate for studies into the processes of calcium regulation and shell deposition in our changing ocean environments.

Results
454 sequencing of L. elliptica mantle tissue generated 18,290 contigs with an average size of 535 bp (ranging between 142 bp-5.591 kb). BLAST sequence similarity searching assigned putative function to 17% of the data set, with a significant proportion of these transcripts being involved in binding and potentially of a secretory nature, as defined by GO molecular function and biological process classifications. These results indicated that the mantle is a transcriptionally active tissue which is actively proliferating. All transcripts were screened against an in-house database of genes shown to be involved in extracellular matrix formation and calcium homeostasis in metazoans. Putative identifications were made for a number of classical shell deposition genes, such as tyrosinase, carbonic anhydrase and metalloprotease 1, along with novel members of the family 2 G-Protein Coupled Receptors (GPCRs). A membrane transport protein (SEC61) was also characterised and this demonstrated the utility of the clam sequence data as a resource for examining cold adapted amino acid substitutions. The sequence data contained 46,235 microsatellites and 13,084 Single Nucleotide Polymorphisms(SNPs/INDELS), providing a resource for population and also gene function studies.

Conclusions
This is the first 454 data from an Antarctic marine invertebrate. Sequencing of mantle tissue from this non-model species has considerably increased resources for the investigation of the processes of shell deposition and repair in molluscs in a changing environment. A number of promising candidate genes were identified for functional analyses, which will be the subject of further investigation in this species and also used in model-hopping experiments in more tractable and economically important model aquaculture species, such as Crassostrea gigas and Mytilus edulis.

Continue reading ‘Insights into shell deposition in the Antarctic bivalve Laternula elliptica: gene discovery in the mantle transcriptome using 454 pyrosequencing’

Spatiotemporal patterns of carbonate sedimentation in the South Atlantic: implications for carbon cycling during the Paleocene–Eocene thermal maximum

Rapid carbon input into the ocean–atmosphere system caused a dramatic shoaling of the lysocline during the Paleocene–Eocene thermal maximum (PETM), a transient (not, vert, similar 170 kyr) global warming event that occurred roughly 55 Ma. Carbon cycle models invoking an accelerated carbonate–silicate feedback mechanism to neutralize ocean acidification predict that the lysocline would subsequently deepen to depths below its original position as the marine carbonate system recovered from such a perturbation. To test this hypothesis, records of carbonate sedimentation and preservation for PETM sections in the Weddell Sea (ODP Site 690) and along the Walvis Ridge depth transect (ODP Sites 1262, 1263, and 1266) were assembled within the context of a unified chronostratigraphy. The meridional gradient of undersaturation delimited by these records shows that dissolution was more severe in the subtropical South Atlantic than in the Weddell Sea during the PETM, a spatiotemporal pattern inconsistent with the view that Atlantic overturning circulation underwent a transient reversal. Deepening of the lysocline following its initial ascent is signaled by increases in %CaCO3 and coarse-fraction content at all sites. Carbonate preservation during the recovery period is appreciably better than that seen prior to carbon input with carbonate sedimentation becoming remarkably uniform over a broad spectrum of geographic and bathymetric settings. These congruent patterns of carbonate sedimentation confirm that the lysocline was suppressed below the depth it occupied prior to carbon input, and are consistent with the view that an accelerated carbonate–silicate geochemical cycle played an important role in arresting PETM conditions.

Continue reading ‘Spatiotemporal patterns of carbonate sedimentation in the South Atlantic: implications for carbon cycling during the Paleocene–Eocene thermal maximum’

The basics of acidification: baseline variability of pH on Australian coral reefs

Ocean acidification is one of the key threats facing coral reef ecosystems, but there are few estimates of spatial and temporal variability in pH among reef habitats. The present study documents levels of spatial variability in pH among coral reef habitats (9 to 10), among locations separated by 100’s km of latitude and between east (Great Barrier Reef, GBR) and west (Ningaloo Reef) coasts of Australia. Differences were found in pH between inshore and offshore waters along Ningaloo Reef (means 8.45, 8.53, respectively). Replicate assessments here ranged from 8.22 to 8.64. On the GBR, the range of values over all habitats and replicates was 0.39 pH units (7.98 to 8.37). There were minor but significant differences of 0.05 pH units between 5 consecutive days for habitats on average. Highest pH was recorded in filamentous algal beds maintained by the damselfish Dischistodus perspicillatus. Lowest pH was found in water extracted from sand-dwelling goby holes. While there were marked changes in pH over a 48-h sampling period among 4 habitats at Lizard Island (GBR), there was little evidence of a diel trend. Understanding how pH varies at scales that are relevant to organisms that live on shallow coral reefs is crucial for the design and interpretation of experiments that test the effects on organisms of the changes in water chemistry predicted to affect oceans in the future.

Continue reading ‘The basics of acidification: baseline variability of pH on Australian coral reefs’

Marine Systems Modeller – CO2 impacts (re-advertised)

Marine Systems Modeller – CO2 impacts

Salary £27,326 – £32,330 p.a.

http://www.pml.ac.uk/about_us/career_opportunities/employment_vacancies.aspx

Plymouth Marine Laboratory (PML) is seeking to appoint a Marine Ecosystem Modeller. This post aims to tackle one of the principal scientific challenges in current marine ecosystem research: to understand and ultimately predict how marine systems respond to high CO2, in particular ocean acidification (OA) and hypothetical leaks from carbon capture and storage (CCS). The focus will be on ecosystem dynamics and biogeochemical cycles in shelf sea benthic systems.

Continue reading ‘Marine Systems Modeller – CO2 impacts (re-advertised)’

Impact of ocean warming and ocean acidification on larval development and calcification in the sea urchin Tripneustes gratilla

Background

As the oceans simultaneously warm, acidify and increase in PCO2, prospects for marine biota are of concern. Calcifying species may find it difficult to produce their skeleton because ocean acidification decreases calcium carbonate saturation and accompanying hypercapnia suppresses metabolism. However, this may be buffered by enhanced growth and metabolism due to warming.

Methodology/Principal Findings

We examined the interactive effects of near-future ocean warming and increased acidification/PCO2 on larval development in the tropical sea urchin Tripneustes gratilla. Larvae were reared in multifactorial experiments in flow-through conditions in all combinations of three temperature and three pH/PCO2 treatments. Experiments were placed in the setting of projected near future conditions for SE Australia, a global change hot spot. Increased acidity/PCO2 and decreased carbonate mineral saturation significantly reduced larval growth resulting in decreased skeletal length. Increased temperature (+3°C) stimulated growth, producing significantly bigger larvae across all pH/PCO2 treatments up to a thermal threshold (+6°C). Increased acidity (-0.3-0.5 pH units) and hypercapnia significantly reduced larval calcification. A +3°C warming diminished the negative effects of acidification and hypercapnia on larval growth.
Conclusions and Significance

This study of the effects of ocean warming and CO2 driven acidification on development and calcification of marine invertebrate larvae reared in experimental conditions from the outset of development (fertilization) shows the positive and negative effects of these stressors. In simultaneous exposure to stressors the dwarfing effects of acidification were dominant. Reduction in size of sea urchin larvae in a high PCO2 ocean would likely impair their performance with negative consequent effects for benthic adult populations.

Continue reading ‘Impact of ocean warming and ocean acidification on larval development and calcification in the sea urchin Tripneustes gratilla’

Effects of elevated CO2 and phosphorus supply on growth, photosynthesis and nutrient uptake in the marine macroalga Gracilaria lemaneiformis (Rhodophyta)

The red alga Gracilaria lemaneiformis was cultured under different CO2 and phosphorus conditions for 16 days, and its growth, photosynthesis and uptake of nitrate and phosphate were examined in order to establish the longer-term impacts of elevated CO2 and phosphorus supplies on this economically important seaweed. Enrichment with either CO2 or phosphorus in culture markedly increased the growth of G. lemaneiformis compared to the control. Light-saturated photosynthetic rate was enhanced significantly by phosphorus enrichment, but hardly affected by the elevation of CO2 when G. lemaneiformis was grown under low phosphorus conditions. High phosphorus stimulated photosynthetic inorganic carbon utilization and nitrogen uptake. Under low phosphorus conditions, the thalli grown at the high level of CO2 had a lower carbon utilization capacity and a higher nitrogen uptake rate compared to those grown under ambient CO2. Reversed results were found when the algae were grown under high phosphorus conditions. Hence, available phosphorus may regulate inorganic carbon utilization of G. lemaneiformis grown at different CO2 levels, and growth reflected a balance between carbon and nutrient metabolism.

Continue reading ‘Effects of elevated CO2 and phosphorus supply on growth, photosynthesis and nutrient uptake in the marine macroalga Gracilaria lemaneiformis (Rhodophyta)’

Sen. Kerry predicts ‘ice-free Arctic’ in ‘5 or 10 years’

Speaking at a town hall-style meeting promoting climate change legislation on Thursday, Sen. John Kerry (D-Mass.) predicted there will be “an ice-free Arctic” in “five or 10 years.”

“The arctic ice is disappearing faster than was predicted,” Kerry said. “And instead of waiting until 2030 or whenever it was to have an ice-free Arctic, we’re going to have one in five or 10 years.”

Continue reading ‘Sen. Kerry predicts ‘ice-free Arctic’ in ‘5 or 10 years’’

Local oysters affected by acidic water; corrosive water threatens Hood Canal

Taylor Shellfish Farms hasn’t had much luck in the past few years.

Its Dabob Bay hatchery, on the north end of Hood Canal, produced 40 percent the oyster larvae needed for a complete catch in 2008, and 20 percent in 2009. This year, spokesman Bill Dewey is optimistic; despite recently published research suggesting water quality problems are here to stay.

Resulting from a recent study, scientists at the University of Washington and the National Oceanic and Atmospheric Administration announced Monday, July 12 that the deep waters of Hood Canal are experiencing remarkably high levels of acidity, which means shellfish are fighting for their lives – and more often than not, they’re losing.

Continue reading ‘Local oysters affected by acidic water; corrosive water threatens Hood Canal’

Ocean warming slows coral growth in the central Red Sea

Sea surface temperature (SST) across much of the tropics has increased by 0.4° to 1°C since the mid-1970s. A parallel increase in the frequency and extent of coral bleaching and mortality has fueled concern that climate change poses a major threat to the survival of coral reef ecosystems worldwide. Here we show that steadily rising SSTs, not ocean acidification, are already driving dramatic changes in the growth of an important reef-building coral in the central Red Sea. Three-dimensional computed tomography analyses of the massive coral Diploastrea heliopora reveal that skeletal growth of apparently healthy colonies has declined by 30% since 1998. The same corals responded to a short-lived warm event in 1941/1942, but recovered within 3 years as the ocean cooled. Combining our data with climate model simulations by the Intergovernmental Panel on Climate Change, we predict that should the current warming trend continue, this coral could cease growing altogether by 2070.

Continue reading ‘Ocean warming slows coral growth in the central Red Sea’

Forscher müssen Mitfahrgelegenheiten nutzen (in German)

Institute und Universitäten müssen sich heute immer öfter mit Industrie und Umweltschützern verbünden.

Es ist eine ungewöhnliche Zusammenarbeit. „Wir möchten diese Forschung unterstützen, weil das Versauern der Ozeane bisher kaum thematisiert wird“, erklärt die Meeresbiologin Iris Menn von der Umweltorganisation Greenpeace. Die Umweltschutzorganisation arbeitet mit dem Leibniz-Institut für Meereswissenschaften (IfM-Geomar) zusammen: In neun sogenannten „Mesokosmen“, die überdimensionalen Reagenzgläsern ähneln, untersuchen 35 Forscher in Spitzbergen, wie der Klimawandel das Meerwasser saurer macht und wie die Organismen darauf reagieren. Geforscht wird von staatlichen Universitäten und öffentlichen Instituten. Transportiert werden die Reagenzgläser von Greenpeace.

Continue reading ‘Forscher müssen Mitfahrgelegenheiten nutzen (in German)’


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