Posts Tagged 'abundance'

A metabolomic approach to investigate effects of ocean acidification on a polar microalga Chlorella sp.

Highlights

• Future ocean acidification levels have little effect on the growth and photosynthesis of Chlorella sp.

• Ocean acidification promoted saturation of fatty acids and amino acid synthesis of Chlorella sp.

• Enhancement of energy production and trehalose synthesis could be the acclimation strategies of marine picochlorophytes.

Abstract

Ocean acidification, due to increased levels of anthropogenic carbon dioxide, is known to affect the physiology and growth of marine phytoplankton, especially in polar regions. However, the effect of acidification or carbonation on cellular metabolism in polar marine phytoplankton still remains an open question. There is some evidence that small chlorophytes may benefit more than other taxa of phytoplankton. To understand further how green polar picoplankton could acclimate to high oceanic CO2, studies were conducted on an Antarctic Chlorella sp. Chlorella sp. maintained its growth rate (∼0.180 d-1), photosynthetic quantum yield (Fv/Fm = ∼0.69) and chlorophyll a (0.145 fg cell-1) and carotenoid (0.06 fg cell-1) contents under high CO2, while maximum rates of electron transport decreased and non-photochemical quenching increased under elevated CO2. GCMS-based metabolomic analysis reveal that this polar Chlorella strain modulated the levels of metabolites associated with energy, amino acid, fatty acid and carbohydrate production, which could favour its survival in an increasingly acidified ocean.

Continue reading ‘A metabolomic approach to investigate effects of ocean acidification on a polar microalga Chlorella sp.’

Ocean acidification may threaten a unique seaweed community and associated industry in the Baltic Sea

Wild harvest of seaweed supports small-scale, high-value industries in a number of regions in the world. Information is lacking on how increasing carbon dioxide (CO2) concentrations in seawater could impact seaweeds in wild harvest situations. This study focuses on a mixed unattached loose-lying red algal community of Furcellaria lumbricalis in close association with Coccotylus truncatus that is found in the West Estonian Archipelago Sea, NE Baltic Sea. In Estonian coastal waters, the wild harvest of F. lumbricalis started in 1960s and it has since been used as raw material for furcellaran production. The aim of this study was to determine how ocean acidification may impact the balance of these two red algal species in the community. Mechanistic assessment of the carbon physiology of F. lumbricalis and C. truncatus was used to predict productivity and competitive interactions between these species in a high-CO2 world. Carbon use strategies in macroalgae were determined by analysing the natural abundances of carbon isotopes (δ13C), pH drift experiments and photosynthesis vs. dissolved inorganic carbon (DIC) curves. Photosynthesis of F. lumbricalis (operating with a CO2 concentrating mechanism or CCM) performed worse along the broader range of DIC concentrations compared to C. truncatus (non-CCM), especially those characterized under future climate conditions. Therefore, changing seawater carbon chemistry through ocean acidification has the potential to influence the balance of F. lumbricalis and C. truncatus in the community and the efficiency of the wild harvest of this community and the quality of product provided.

Continue reading ‘Ocean acidification may threaten a unique seaweed community and associated industry in the Baltic Sea’

Ulva prolifera green-tide outbreaks and their environmental impact in the Yellow Sea, China

The Ulva prolifera green tides in the Yellow Sea, China, which have been occurring since 2007, are a serious environmental problem attracting worldwide attention. Despite extensive research, the outbreak mechanisms have not been fully understood. Comprehensive analysis of anthropogenic and natural biotic and abiotic factors reveals that human activities, regional physicochemical conditions and algal physiological characteristics as well as ocean warming and biological interactions (with microorganism or other macroalgae) are closely related to the occurrence of green tides. Dynamics of these factors and their interactions could explain why green tides suddenly occurred in 2007 and decreased abruptly in 2017. Moreover, the consequence of green tides is serious. The decay of macroalgal biomass could result in hypoxia and acidification, possibly induce red tide and even have a long-lasting impact on coastal carbon cycles and the ecosystem. Accordingly, corresponding countermeasures have been proposed in our study for future reference in ecosystem management strategies and sustainable development policy.

Continue reading ‘Ulva prolifera green-tide outbreaks and their environmental impact in the Yellow Sea, China’

Epibenthic community variation along an acidified tropical estuarine system

The benthic communities associated with hard substrata in tropical estuaries (rocky surfaces and mangrove roots) are underexplored compared to sediment-associated communities. Being unaffected by within-sediment chemistry, rocky surface communities are exposed to water-column chemistry. Natural and anthropogenic acidic inflows into estuaries are common, yet understanding of how low pH estuarine water impacts communities is limited. This study investigated variation in a rocky substratum benthic community along a steep pH and carbonate saturation gradient in a tropical estuary. Samples (n=72) samples were collected from four stations in the Brunei estuarine system, South East Asia (pH 5.78 – 8.1, salinity 0.1 – 29.5 psu). Species richness, diversity and abundance were greatest at the seaward end of the estuary (where pH and salinity were high), reduced in the middle estuary, and relatively high again in the upper estuary. A total of 34 species were recorded, with station abundances varying between 95 and 336 individuals/100 cm2. At a coarse taxonomic level (class/order), multivariate analyses revealed three distinct communities, a tanaid–polychaete dominated community, a mussel–dipteran community, and a mussel–amphipod–dipteran community. The observed shift from amphipod-dominance to polychaete-dominance along a decreasing pH gradient is consistent with the community changes seen in open ocean systems influenced by elevated pCO2. This study is the first description of community structure variation for hard-substratum invertebrates in an old-world tropical estuary. It shows that acidified estuaries offer insights into community-level responses to marine acidification in general.

Continue reading ‘Epibenthic community variation along an acidified tropical estuarine system’

Coastal dynamic, nitrate (NO3-) phosphate (PO4-) and phytoplankton abundance at Morodemak North Java Sea Indonesia

Coastal dynamic of North Java sea was the influence of the west and east monsoon as well as interseasonal effect during April-June and October-December. Espescialy to coastal current patern and to nitrate and phosphate variation and ultimately to phytoplankton. Study area focused at 110°52’03.72”E – 110°54’68” E and 06°80.4’75”S – 06°82’72.22”S. The study was conducted for 1 mont in September 2014. Location of this research at Morodemak waters of North Java Sea. Aim of study was to built current spatial model, measure insitu nitrate and phosphate variation and phytoplankton abundance. Coastal current spatial modelling was done using SMS-v8.1 and sampling site based to purposive sampling represetative to the estuary and coastal system. Spatial modelling using Arc.GIS 10 software. The study revealed that nitrate concentration ranged at 0.60 – 2.0 mg/l, phosphate 0.04 – 0.24 mg/l and current speed 0.0003 – 0.0033 m/sec to southeast direction. About 22 genera of phytoplankton were found, with moderate dominancy of Baccilariophyceae, Dinophyceae and most dominance of Rhizosolenia. Most abundance of phytoplankton was at the mouth of the river or the estuary with 28,090,000 cell/m3. Lowest abundance at offshore coastal site with 17,060,000 cell/m3. The highest diversity index (H’) was 1.606 at the estuary and the lowest was 0.8730 at coastal offshore.

Continue reading ‘Coastal dynamic, nitrate (NO3-) phosphate (PO4-) and phytoplankton abundance at Morodemak North Java Sea Indonesia’

Elevated temperature and decreased salinity both affect the biochemical composition of the Antarctic sea-ice diatom Nitzschia lecointei, but not increased pCO2

Areas in western Antarctica are experiencing rapid climate change, where ocean warming results in more sea ice melt simultaneously as oceanic CO2 levels are increasing. In this study, we have tested how increased temperature (from −1.8 to 3 °C) and decreased salinity (from 35 to 20 and 10) synergistically affect the growth, photophysiology and biochemical composition of the Antarctic sea-ice diatom Nitzschia lecointei. In a separate experiment, we also addressed how ocean acidification (from 400 to 1000 µatm partial pressure of CO2) affects these key physiological parameters. Both positive and negative changes in specific growth rate, particulate organic carbon to particulate organic nitrogen ratio, chl a fluorescence kinetics, lipid peroxidation, carbohydrate content, protein content, fatty acid content and composition were observed when cells were exposed to warming and desalination. However, when cells were subjected to increased pCO2, only Fv/Fm, non-photochemical quenching and lipid peroxidation increased (by 3, 16 and 14%, respectively), and no other of the abovementioned biochemical properties were affected. These results suggest that changes in temperature and salinity may have more effects on the biochemical composition of N. lecointei than ocean acidification. Sea-ice algae are important component of polar food webs, and their nutritional quality may be affected as a result of altered environmental conditions due to climate change and sea ice melt.

Continue reading ‘Elevated temperature and decreased salinity both affect the biochemical composition of the Antarctic sea-ice diatom Nitzschia lecointei, but not increased pCO2’

Hidden biogeochemical anonymities under Antarctic fast ice

Climate change is negatively affecting the extent of summer sea ice and the global oceanic oxygen concentrations, it is therefore imperative to decipher the life processes under the Antarctic fast ice. The biogeochemical parameters like dissolved oxygen, inorganic carbon, macronutrients, phytoplankton, and chlorophyll a (Chl a) were studied under the fast ice (by drilling 1.8 m thick ice) around Larsemann Hills, East Antarctica during India’s Scientific Expedition to Antarctica (31-ISEA-2011/12 and 33-ISEA-2013/14). The waters under ice cover were characterized by hyperoxia (up to 10.6 ml/L). Macronutrient concentrations under sea ice were depleted (<0.1 M NO3, PO4 and <2 M SiO4); this could be ascribed to the nutrient demand from under ice algae. The water under the ice cover exhibited higher algal biomass (Chl a up to 6.1 mg/m3) and CO2 under saturation (pCO2 <10 atm). This is reflected through the Spearman rank correlation indicating a negative correlation between Chl a and pCO2 (). The strong negative correlation between dissolved oxygen and pCO2 () suggests that photosynthesis regulates the concentrations of both these climatically important gases. The waters under the sea ice cover had brownish mucilaginous aggregates comprised of tube-forming diatoms Berkeleya adelienses and Nitzschia lecointei. These unusual biogeochemical changes were seen only at the ice water interface, and not at deeper depths. This study suggests that with global warming and sea ice melting, Antarctica might witness phytoplankton community shifts.

Continue reading ‘Hidden biogeochemical anonymities under Antarctic fast ice’


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Ocean acidification in the IPCC AR5 WG II

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