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Effects of elevated CO2 on phytoplankton community biomass and species composition during a spring Phaeocystis spp. bloom in the western English Channel

A 21-year time series of phytoplankton community structure was analysed in relation to Phaeocystis spp. to elucidate its contribution to the annual carbon budget at station L4 in the western English Channel (WEC).

Between 1993–2014 Phaeocystis spp. contributed ∼4.6% of the annual phytoplankton carbon and during the March − May spring bloom, the mean Phaeocystis spp. biomass constituted 17% with a maximal contribution of 47% in 2001. Upper maximal weekly values above the time series mean ranged from 63 to 82% of the total phytoplankton carbon (∼42–137 mg carbon (C) m−3) with significant inter-annual variability in Phaeocystis spp. Maximal biomass usually occurred by the end of April, although in some cases as early as mid-April (2007) and as late as late May (2013).

The effects of elevated pCO2 on the Phaeocystis spp. spring bloom were investigated during a fifteen-day semi-continuous microcosm experiment. The phytoplankton community biomass was estimated at ∼160 mg C m−3 and was dominated by nanophytoplankton (40%, excluding Phaeocystis spp.), Phaeocystis spp. (30%) and cryptophytes (12%). The smaller fraction of the community biomass comprised picophytoplankton (9%), coccolithophores (3%), Synechococcus (3%), dinoflagellates (1.5%), ciliates (1%) and diatoms (0.5%). Over the experimental period, total biomass increased significantly by 90% to ∼305 mg C m−3 in the high CO2 treatment while the ambient pCO2 control showed no net gains. Phaeocystis spp. exhibited the greatest response to the high CO2 treatment, increasing by 330%, from ∼50 mg C m−3 to over 200 mg C m−3 and contributing ∼70% of the total biomass.

Taken together, the results of our microcosm experiment and analysis of the time series suggest that a future high CO2 scenario may favour dominance of Phaeocystis spp. during the spring bloom. This has significant implications for the formation of hypoxic zones and the alteration of food web structure including inhibitory feeding effects and lowered fecundity in many copepod species.

Continue reading ‘Effects of elevated CO2 on phytoplankton community biomass and species composition during a spring Phaeocystis spp. bloom in the western English Channel’

The spirit of collaboration aboard Gulf of Mexico cruise

This summer, NOAA and partner scientists will conduct their most collaborative ocean acidification sampling of the Gulf of Mexico yet. Set to depart today, July 18th, the Gulf of Mexico Ecosystems and Carbon Cruise (GOMECC-3) will travel through international waters with 24 scientists from the United States, Mexico and Cuba on board.

This comprehensive month-long effort is driven by the growing collaboration within the ocean acidification science community and the multitude of communities that rely on the changing Gulf. The cruise will be the first all inclusive research cruise to document ocean acidification impacts to US living marine resources in the Gulf of Mexico, which is called for under the Federal Ocean Acidification Research And Monitoring Act of 2009 (FOARAM).

Continue reading ‘The spirit of collaboration aboard Gulf of Mexico cruise’

Snow Dragon to assess acidification of Arctic Ocean

The Chinese icebreaker Xuelong, or Snow Dragon, will set sail on Thursday for a research mission to discover the extent of acidification in the Arctic Ocean.

It is internationally acknowledged that acidification — mainly caused by carbon dioxide emissions into the sea — is rising in the ocean and already covers a larger area, according to Xu Ren, deputy director of the Polar Research Institute of China.

“It may trigger environmental disasters and affect marine biodiversity,” he said at a media briefing on Tuesday. “Ocean acidification is a major issue facing the international community, along with global warming and marine pollution.

Continue reading ‘Snow Dragon to assess acidification of Arctic Ocean’

Team deciphers secrets of undersea chemical reaction; can it reduce CO2 in the atmosphere?

Scientists speed up a natural process that occurs deep in the ocean, raising the possibility that humans could help the Earth cope with greenhouse gases

Scientists at USC and Caltech have accelerated a normally slow, natural chemical reaction by a factor of 500, which could store and neutralize carbon in the deepest recesses of the ocean without harming coral or other organisms.

For the first time ever, the USC-Caltech team was able to measure very precisely the reaction rate of calcite, a form of calcium carbonate, as it dissolved in seawater enhanced by a common enzyme, carbonic anhydrase. That’s the same enzyme that maintains the acid-base balance in the blood and tissue of humans and other animals.

Continue reading ‘Team deciphers secrets of undersea chemical reaction; can it reduce CO2 in the atmosphere?’

The future of ocean exploration (video)

A mini-documentary exploring the amazing future of oceanographic discovery, featuring biofluorescent sharks, deep sea mining, seafloor vents, ROV’s (remote operated vehicles), and the disturbing effects of ocean acidification.

(Part on ocean acidification starts at 5.30 and ends at 8.07).

 

Continue reading ‘The future of ocean exploration (video)’

Genome-wide identification, characterization and expression analyses of TLRs in Yesso scallop (Patinopecten yessoensis) provide insight into the disparity of responses to acidifying exposure in bivalves

  Highlights

  • Eighteen TLR superfamily members were identified in the P. yessoensis genome.
  • Phylogenetic analysis confirmed duplication and expansion of TLR genes in mollusk.
  • The 18 PyTLRs showed different immune response patterns to acidifying exposure.
  • Adaptive recruitment of tandem duplication of TLR genes have been arisen to the immune stress.

Abstract

Toll-like receptors (TLRs) play a crucial role in innate immunity by recognizing specific pathogen-associated molecular patterns, including lipoproteins, lipopeptides, lipopolysaccharide, flagellin, dsRNA, ssRNA and CpG DNA motifs. Although significant effects of TLRs on immunity have been reported in most vertebrates and some invertebrates, the complete TLR superfamily has not been systematically characterized in scallops. In this study, 18 TLR genes were identified from Yesso scallop (Patinopecten yessoensis) using whole-genome scanning. Phylogenetic and protein structural analyses were performed to determine the identities and evolutionary relationships of the 18 genes. Extensive expansion of TLR genes from the Yesso scallop genome indicated gene duplication events. In addition, expression profiling of PyTLRs was performed at different acidifying exposure levels (pH = 6.50, 7.50) with different challenge durations (3, 6, 12 and 24 h) via in silico analysis using transcriptome and genome databases. Our results confirmed the inducible expression patterns of PyTLRs under acidifying exposure, and the responses to immune stress may have arisen through adaptive recruitment of tandem duplications of TLR genes. Collectively, this study provides novel insight into PyTLRs as well as the specific role and response of TLR signaling pathways in host immune responses against acidifying exposure in bivalves.

 

Continue reading ‘Genome-wide identification, characterization and expression analyses of TLRs in Yesso scallop (Patinopecten yessoensis) provide insight into the disparity of responses to acidifying exposure in bivalves’

Carbonate system properties in the Gerlache Strait, Northern Antarctic Peninsula (February 2015): II. Anthropogenic CO2 and seawater acidification

Highlights

  • Anthropogenic carbon has reached the deep waters (≥ 100 m) of Gerlache Strait, Antarctica.
  • The main intrusion of anthropogenic carbon in the deep basin of the Gerlache Strait is through the advection of HSSW-derived water into the region.
  • A small additional input of anthropogenic carbon at depth can trigger the dissolution of aragonite.


Abstract

During the NAUTILUS I cruise in February 2015, the carbonate and associated physical properties were measured throughout the water column in the Gerlache Strait—off the southern coast of the Northern Antarctic Peninsula (NAP). Part I of this study (Kerr et al., 2017, this issue) focused on the net sea–air carbon dioxide (CO2) flux, whereas the same dataset was used here to estimate the extent of anthropogenic carbon (Cant) storage in the Gerlache Strait deep basin. In addition, the impact of Cant increases on pH and calcium carbonate saturation states for calcite and aragonite (ΩCa and ΩAr, respectively) were evaluated. The results indicate that, up to the present, 21.2 ± 16.7 μmol kg−1 of Cant have been injected to the deep and bottom layers of the Gerlache Strait. Two mechanisms may have contributed to that fact: (i) the pathway of the Cant follows that of the high salinity shelf waters inflow coming from both the Bransfield Strait and the Northwestern Weddell Sea shelf, and (ii) the Gerlache Strait is absorbing a significant amount of Cant from the atmosphere. Therefore, pH, ΩAr and ΩCa are decreasing in the deep waters of the Gerlache Strait. Since ΩAr is already very close to 1 at depth, any small additional input of Cant will trigger the dissolution of aragonite.

Continue reading ‘Carbonate system properties in the Gerlache Strait, Northern Antarctic Peninsula (February 2015): II. Anthropogenic CO2 and seawater acidification’


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Ocean acidification in the IPCC AR5 WG II

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