scholarly journals High tolerance of microzooplankton to ocean acidification in an Arctic coastal plankton community

2013 ◽  
Vol 10 (3) ◽  
pp. 1471-1481 ◽  
Author(s):  
N. Aberle ◽  
K. G. Schulz ◽  
A. Stuhr ◽  
A. M. Malzahn ◽  
A. Ludwig ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Indirect Effects ◽  
High Arctic ◽  
Taxonomic Composition ◽  
High Pco2 ◽  
Marine Biota ◽  
High Tolerance ◽  
Wide Range ◽  
Low Sensitivity ◽  
The Impact

Abstract. Impacts of ocean acidification (OA) on marine biota have been observed in a wide range of marine systems. We used a mesocosm approach to study the response of a high Arctic coastal microzooplankton community during the post-bloom period in Kongsfjorden (Svalbard) to direct and indirect effects of high pCO2/low pH. We found almost no direct effects of OA on microzooplankton composition and diversity. Both the relative shares of ciliates and heterotrophic dinoflagellates as well as the taxonomic composition of microzooplankton remained unaffected by changes in pCO2/pH. Although the different pCO2 treatments affected food availability and phytoplankton composition, no indirect effects (e.g. on the total carrying capacity and phenology of microzooplankton) could be observed. Our data point to a high tolerance of this Arctic microzooplankton community to changes in pCO2/pH. Future studies on the impact of OA on plankton communities should include microzooplankton in order to test whether the observed low sensitivity to OA is typical for coastal communities where changes in seawater pH occur frequently.

scholarly journals High tolerance of protozooplankton to ocean acidification in an Arctic coastal plankton community

2012 ◽  
Vol 9 (9) ◽  
pp. 13031-13051 ◽  
Author(s):  
N. Aberle ◽  
K. G. Schulz ◽  
A. Stuhr ◽  
A. Ludwig ◽  
U. Riebesell
Keyword(s):  
Ocean Acidification ◽  
Indirect Effects ◽  
High Arctic ◽  
Taxonomic Composition ◽  
High Pco2 ◽  
Marine Biota ◽  
High Tolerance ◽  
Wide Range ◽  
Low Sensitivity ◽  
The Impact

Abstract. Impacts of ocean acidification (OA) on marine biota have been observed in a wide range of marine systems. We used a mesocosm approach to study the response of a high Arctic coastal protozooplankton (PZP in the following) community during the post-bloom period in the Kongsfjorden (Svalbard) to direct and indirect effects of high pCO2/low pH. We found almost no direct effects of OA on PZP composition and diversity. Both, the relative shares of ciliates and heterotrophic dinoflagellates as well as the taxonomic composition of protozoans remained unaffected by changes in pCO2/pH. The different pCO2 treatments did not have any effect on food availability and phytoplankton composition and thus no indirect effects e.g. on the total carrying capacity and phenology of PZP could be observed. Our data points at a high tolerance of this Arctic PZP community to changes in pCO2/pH. Future studies on the impact of OA on plankton communities should include PZP in order to test whether the observed low sensitivity of protozoans to OA is typical for coastal communities where changes in seawater pH occur frequently.

Not All Transformational Leadership Behaviors Are Equal: The Impact of Followers’ Identification With Leader and Modernity on Taking Charge

2016 ◽  
Vol 24 (3) ◽  
pp. 318-334 ◽  
Author(s):  
Jie Li ◽  
Stacie Furst-Holloway ◽  
Larry Gales ◽  
Suzanne S. Masterson ◽  
Brian D. Blume
Keyword(s):  
Transformational Leadership ◽  
Indirect Effects ◽  
High Performance ◽  
Relative Effect ◽  
Future Research ◽  
Intellectual Stimulation ◽  
Performance Expectations ◽  
Wide Range ◽  
Taking Charge ◽  
The Impact

This study investigates how each dimension of transformational leadership directly and indirectly influences followers’ change-oriented behaviors. Using a sample of 329 independent leader–follower dyads from a wide range of Chinese organizations, we examine followers’ identification with leader as an intervening variable between the four dimensions of transformational leadership (“core” transformational behaviors, high-performance expectations, individualized support, and intellectual stimulation) and followers’ taking charge behaviors. Results showed that intellectual stimulation had the highest relative effect size that was largely due to its direct effect on taking charge. Individualized support only exerted a significant indirect effect. Additionally, the negative direct and positive indirect effects of high-performance expectations rendered its total effect nonsignificant. Furthermore, the direct, indirect, and total effects of “core” transformational behaviors were nonsignificant. We also found that followers’ value of modernity moderated the effect of identification with leader on taking charge. The indirect effects of intellectual stimulation, individualized support, and high-performance expectations were significant when modernity was high but nonsignificant when it was low. Implications for theory, practice, and future research are discussed.

Direct and indirect effects of near-future pCO2 levels on zooplankton dynamics

2017 ◽  
Vol 68 (2) ◽  
pp. 373 ◽  
Author(s):  
Cédric L. Meunier ◽  
María Algueró-Muñiz ◽  
Henriette G. Horn ◽  
Julia A. F. Lange ◽  
Maarten Boersma
Keyword(s):  
Ocean Acidification ◽  
Indirect Effects ◽  
Trophic Levels ◽  
Model Organisms ◽  
High Pco2 ◽  
Direct And Indirect Effects ◽  
Oxyrrhis Marina ◽  
Short Term Exposure ◽  
Zooplankton Growth ◽  
Seawater Pco2

Ocean acidification has direct physiological effects on organisms, for example by dissolving the calcium carbonate structures of calcifying species. However, non-calcifiers may also be affected by changes in seawater chemistry. To disentangle the direct and indirect effects of ocean acidification on zooplankton growth, we undertook a study with two model organisms. Specifically, we investigated the individual effects of short-term exposure to high and low seawater pCO2, and different phytoplankton qualities as a result of different CO2 incubations on the growth of a heterotrophic dinoflagellate (Oxyrrhis marina) and a copepod species (Acartia tonsa). It was observed previously that higher CO2 concentrations can decrease phytoplankton food quality in terms of carbon:nutrient ratios. We therefore expected both seawater pCO2 (pH) and phytoplankton quality to result in decreased zooplankton growth. Although we expected lowest growth rates for all zooplankton under high seawater pCO2 and low algal quality, we found that direct pH effects on consumers seem to be of lesser importance than the associated decrease in algal quality. The decrease in the quality of primary producers under high pCO2 conditions negatively affected zooplankton growth, which may lead to lower availability of food for the next trophic level and thus potentially affect the recruitment of higher trophic levels.

scholarly journals Investigating the effect of nickel concentration on phytoplankton growth to inform the assessment of ocean alkalinity enhancement

2022 ◽  
Author(s):  
Jiaying Abby Guo ◽  
Robert Strzepek ◽  
Anusuya Willis ◽  
Aaron Ferderer ◽  
Lennart Thomas Bach
Keyword(s):  
Nitrogen Source ◽  
Organic Ligand ◽  
Marine Phytoplankton ◽  
Growth Media ◽  
Accelerated Weathering ◽  
Marine Biota ◽  
Phytoplankton Species ◽  
Phytoplankton Communities ◽  
Wide Range ◽  
The Impact

Abstract. Ocean alkalinity enhancement (OAE) is a proposed method for removing carbon dioxide (CO2) from the atmosphere by the accelerated weathering of (ultra-) basic minerals to increase alkalinity – the chemical capacity of seawater to store CO2. During the weathering of OAE-relevant minerals relatively large amounts of trace metals will be released and may perturb pelagic ecosystems. Nickel (Ni) is of particular concern as it is abundant in olivine, one of the most widely considered minerals for OAE. However, so far there is limited knowledge about the impact of Ni on marine biota including phytoplankton. To fill this knowledge gap, this study tested the growth and photo-physiological response of 11 marine phytoplankton species to a wide range of dissolved Ni concentrations (from 0 nmol/L to 50,000 nmol/L). We found that the phytoplankton species were not very sensitive to Ni concentrations under the culturing conditions established in our experiments, but the responses were species-specific. The growth rates of 6 of the 11 tested species showed small but significant responses to changing Ni concentrations. Photosynthetic performance, assessed by measuring the maximum quantum yield (Fv/Fm) and the functional absorption cross-section (σPSII) of photosystem II, was also only mildly sensitive to changing Ni in 3 out of 11 species and 4 out of 11 species, respectively. The limited effect of Ni may be partly due to the provision of nitrate as the nitrogen source for growth, as previous studies suggest higher sensitivities when urea is the nitrogen source. Furthermore, limited influence may be due to the relatively high concentrations of organic ligands in the growth media in our experiments. These ligands reduced bioavailable Ni (i.e., “free Ni2+”) concentrations by binding the majority of the dissolved Ni. Our data suggest that dissolved Ni does not have a strong effect on phytoplankton under our experimental conditions, but we emphasize that a deeper understanding of nitrogen sources, ligand concentrations and phytoplankton composition is needed when assessing the influence of Ni release associated with OAE. We discuss if applications of OAE with Ni-rich minerals may be safer in regions with high organic ligand concentrations and low concentrations of urea as such boundary conditions may lead to less impact of Ni on phytoplankton communities.

scholarly journals The scale problem in quantifying aerosol indirect effects

2011 ◽  
Vol 11 (9) ◽  
pp. 26741-26789 ◽  
Author(s):  
A. McComiskey ◽  
G. Feingold
Keyword(s):  
Indirect Effects ◽  
Radiative Forcing ◽  
Liquid Water Path ◽  
Aerosol Indirect Effects ◽  
Remote Sensors ◽  
Cloud Properties ◽  
Wide Range ◽  
Albedo Effect ◽  
Cloud Liquid Water Path ◽  
The Impact

Abstract. A wide range of estimates exists for the radiative forcing of the aerosol effect on cloud albedo. We argue that a component of this uncertainty derives from the use of a wide range of observational scales and platforms. Aerosol affects cloud properties at the microphysical scale, or the "process scale" but observations are most often made of bulk properties over a wide range of resolutions, or "analysis scales". We show that differences between process and analysis scales incur biases in quantification of the albedo effect through the impact that data aggregation has on statistical properties of the aerosol or cloud variable, and their covariance. Measures made within this range of scales are erroneously treated as equivalent, leading to a large uncertainty in associated radiative forcing estimates. Issues associated with the coarsening of observational resolution particular to quantifying the albedo effect are discussed. Specifically, the omission of the constraint on cloud liquid water path and the separation in space of cloud and aerosol properties from passive, space-based remote sensors dampen the measured strength of the albedo effect. Based on our understanding of these biases we propose a new approach for an observationally-based, robust method for estimating aerosol indirect effects that can be used for radiative forcing estimates as well as a better characterization of the uncertainties associated with those estimates.

scholarly journals Skeletal mineralogy of coral recruits under high temperature and <i>p</i>CO<sub>2</sub>

2016 ◽  
Vol 13 (5) ◽  
pp. 1717-1722 ◽  
Author(s):  
T. Foster ◽  
P. L. Clode
Keyword(s):  
High Temperature ◽  
Ocean Acidification ◽  
High Pco2 ◽  
X Ray Diffraction ◽  
Calcite Precipitation ◽  
Ambient Seawater ◽  
The Past ◽  
Coral Reef Ecosystems ◽  
Combined Impact ◽  
The Impact

Abstract. Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility may leave animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg ∕ Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ∼ 540 Ma. Experimentally reduced Mg ∕ Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals; however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of 1-month-old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (∼ 900 µatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be the investigation of the combined impact of high pCO2 and reduced Mg ∕ Ca ratio on coral skeletal mineralogy.

scholarly journals Seagrass beds as ocean acidification refuges for mussels? High resolution measurements of <i>p</i>CO<sub>2</sub> and O<sub>2</sub> in a <i>Zostera marina</i> and <i>Mytilus edulis</i> mosaic habitat

2015 ◽  
Vol 12 (14) ◽  
pp. 11423-11461 ◽  
Author(s):  
V. Saderne ◽  
P. Fietzek ◽  
S. Aßmann ◽  
A. Körtzinger ◽  
C. Hiebenthal
Keyword(s):  
High Resolution ◽  
Ocean Acidification ◽  
High Pco2 ◽  
Seagrass Beds ◽  
Carbonate Chemistry ◽  
Calcium Carbonates ◽  
Positive Side ◽  
Chemical Conditions ◽  
Technological Limitations ◽  
The Impact

Abstract. It has been speculated that macrophytes beds might act as a refuge for calcifiers from ocean acidification. In the shallow nearshores of the western Kiel Bay (Baltic Sea), mussel and seagrass beds are interlacing, forming a mosaic habitat. Naturally, the diverse physiological activities of seagrasses and mussels are affected by seawater carbonate chemistry and they locally modify it in return. Calcification by shellfishes is sensitive to seawater acidity; therefore the photosynthetic activity of seagrasses in confined shallow waters creates favorable chemical conditions to calcification at daytime but turn the habitat less favorable or even corrosive to shells at night. In contrast, mussel respiration releases CO2, turning the environment more favorable for photosynthesis by adjacent seagrasses. At the end of summer, these dynamics are altered by the invasion of high pCO2/low O2 coming from the deep water of the Bay. However, it is in summer that mussel spats settle on the leaves of seagrasses until migrating to the permanent habitat where they will grow adult. These early life phases (larvae/spats) are considered as most sensitive with regard to seawater acidity. So far, the dynamics of CO2 have never been continuously measured during this key period of the year, mostly due to the technological limitations. In this project we used a combination of state-of-the-art technologies and discrete sampling to obtain high-resolution time-series of pCO2 and O2 at the interface between a seagrass and a mussel patch in Kiel Bay in August and September 2013. From these, we derive the entire carbonate chemistry using statistical models. We found the monthly average pCO2 more than 50 % (approx. 640 μatm for August and September) above atmospheric equilibrium right above the mussel patch together with large diel variations of pCO2 within 24 h: 887 ± 331 μatm in August and 742 ± 281 μatm in September (mean ± SD). We observed important daily corrosiveness for calcium carbonates (Ωarag and Ωcalc < 1) centered on sunrise. On the positive side, the investigated habitat never suffered from hypoxia during the study period. We emphasize the need for more experiments on the impact of these acidic conditions on (juvenile) mussels with a focus on the distinct day-night variations observed.

scholarly journals Skeletal mineralogy of coral recruits under high temperature and <i>p</i>CO<sub>2</sub>

2015 ◽  
Vol 12 (15) ◽  
pp. 12485-12500 ◽  
Author(s):  
T. Foster ◽  
P. L. Clode
Keyword(s):  
High Temperature ◽  
Ocean Acidification ◽  
High Pco2 ◽  
X Ray Diffraction ◽  
Calcite Precipitation ◽  
Ambient Seawater ◽  
The Past ◽  
Coral Reef Ecosystems ◽  
Combined Impact ◽  
The Impact

Abstract. Aragonite, which is the polymorph of CaCO3 precipitated by modern corals during skeletal formation, has a higher solubility than the more stable polymorph calcite. This higher solubility leaves animals that produce aragonitic skeletons more vulnerable to anthropogenic ocean acidification. It is therefore, important to determine whether scleractinian corals have the plasticity to adapt and produce calcite in their skeletons in response to changing environmental conditions. Both high pCO2 and lower Mg / Ca ratios in seawater are thought to have driven changes in the skeletal mineralogy of major marine calcifiers in the past ∼540 myr. Experimentally reduced Mg / Ca ratios in ambient seawater have been shown to induce some calcite precipitation in both adult and newly settled modern corals, however, the impact of high pCO2 on the mineralogy of recruits is unknown. Here we determined the skeletal mineralogy of one-month old Acropora spicifera coral recruits grown under high temperature (+3 °C) and pCO2 (∼900 μatm) conditions, using X-ray diffraction and Raman spectroscopy. We found that newly settled coral recruits produced entirely aragonitic skeletons regardless of the treatment. Our results show that elevated pCO2 alone is unlikely to drive changes in the skeletal mineralogy of young corals. Not having an ability to switch from aragonite to calcite precipitation may leave corals and ultimately coral reef ecosystems more susceptible to predicted ocean acidification. An important area for prospective research would be to investigate the combined impact of high pCO2 and reduced Mg / Ca ratio on coral skeletal mineralogy.

scholarly journals Species interactions can shift the response of a maerl bed community to ocean acidification and warming

2017 ◽  
Vol 14 (23) ◽  
pp. 5359-5376 ◽  
Author(s):  
Erwann Legrand ◽  
Pascal Riera ◽  
Mathieu Lutier ◽  
Jérôme Coudret ◽  
Jacques Grall ◽  
...  
Keyword(s):  
Primary Production ◽  
Ocean Acidification ◽  
Species Interactions ◽  
Gross Primary Production ◽  
Benthic Communities ◽  
Community Response ◽  
High Pco2 ◽  
Effects Of Temperature ◽  
The Impact ◽  
Positive Effect

Abstract. Predicted ocean acidification and warming are likely to have major implications for marine organisms, especially marine calcifiers. However, little information is available on the response of marine benthic communities as a whole to predicted changes. Here, we experimentally examined the combined effects of temperature and partial pressure of carbon dioxide (pCO2) increases on the response of maerl bed assemblages, composed of living and dead thalli of the free-living coralline alga Lithothamnion corallioides, epiphytic fleshy algae, and grazer species. Two 3-month experiments were performed in the winter and summer seasons in mesocosms with four different combinations of pCO2 (ambient and high pCO2) and temperature (ambient and +3 °C). The response of maerl assemblages was assessed using metabolic measurements at the species and assemblage scales. This study suggests that seasonal variability represents an important driver influencing the magnitude and the direction of species and community response to climate change. Gross primary production and respiration of assemblages was enhanced by high pCO2 conditions in the summer. This positive effect was attributed to the increase in epiphyte biomass, which benefited from higher CO2 concentrations for growth and primary production. Conversely, high pCO2 drastically decreased the calcification rates in assemblages. This response can be attributed to the decline in calcification rates of living L. corallioides due to acidification and increased dissolution of dead L. corallioides. Future changes in pCO2 and temperature are likely to promote the development of non-calcifying algae to the detriment of the engineer species L. corallioides. The development of fleshy algae may be modulated by the ability of grazers to regulate epiphyte growth. However, our results suggest that predicted changes will negatively affect the metabolism of grazers and potentially their ability to control epiphyte abundance. We show here that the effects of pCO2 and temperature on maerl bed communities were weakened when these factors were combined. This underlines the importance of examining multi-factorial approaches and community-level processes, which integrate species interactions, to better understand the impact of global change on marine ecosystems.

scholarly journals Early-life exposure to climate change impairs tropical shark survival

2014 ◽  
Vol 281 (1793) ◽  
pp. 20141738 ◽  
Author(s):  
Rui Rosa ◽  
Miguel Baptista ◽  
Vanessa M. Lopes ◽  
Maria Rita Pegado ◽  
José Ricardo Paula ◽  
...  
Keyword(s):  
Climate Change ◽  
Ocean Acidification ◽  
Habitat Degradation ◽  
Ecological Niches ◽  
Marine Animals ◽  
Early Life Exposure ◽  
Wide Range ◽  
C 30 ◽  
Proactive Measures ◽  
The Impact

Sharks are one of the most threatened groups of marine animals worldwide, mostly owing to overfishing and habitat degradation/loss. Although these cartilaginous fish have evolved to fill many ecological niches across a wide range of habitats, they have limited capability to rapidly adapt to human-induced changes in their environments. Contrary to global warming, ocean acidification was not considered as a direct climate-related threat to sharks. Here we show, for the first time, that an early ontogenetic acclimation process of a tropical shark ( Chiloscyllium punctatum ) to the projected scenarios of ocean acidification (ΔpH = 0.5) and warming (+4°C; 30°C) for 2100 elicited significant impairments on juvenile shark condition and survival. The mortality of shark embryos at the present-day thermal scenarios was 0% both at normocapnic and hypercapnic conditions. Yet routine metabolic rates (RMRs) were significantly affected by temperature, pH and embryonic stage. Immediately after hatching, the Fulton condition of juvenile bamboo sharks was significantly different in individuals that experienced future warming and hypercapnia; 30 days after hatching, survival rapidly declined in individuals experiencing both ocean warming and acidification (up to 44%). The RMR of juvenile sharks was also significantly affected by temperature and pH. The impact of low pH on ventilation rates was significant only under the higher thermal scenario. This study highlights the need of experimental-based risk assessments of sharks to climate change. In other words, it is critical to directly assess risk and vulnerability of sharks to ocean acidification and warming, and such effort can ultimately help managers and policy-makers to take proactive measures targeting most endangered species.

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