Community composition has greater impact on the functioning of marine phytoplankton communities than ocean acidification

2014 ◽  
Vol 20 (3) ◽  
pp. 713-723 ◽  
Author(s):  
Sarah L. Eggers ◽  
Aleksandra M. Lewandowska ◽  
Joana Barcelos e Ramos ◽  
Sonia Blanco-Ameijeiras ◽  
Francesca Gallo ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Community Composition ◽  
Marine Phytoplankton ◽  
Phytoplankton Communities

scholarly journals Responses of the diatom <i>Asterionellopsis glacialis</i> to increasing sea water CO<sub>2</sub> concentrations and the effect of turbulence

2016 ◽  
Author(s):  
Francesca Gallo ◽  
Kai G. Schulz ◽  
Eduardo B. Azevedo ◽  
João Madruga ◽  
Joana Barcelos e Ramos
Keyword(s):  
Carbon Dioxide ◽  
Ocean Acidification ◽  
Growth Rates ◽  
Sea Water ◽  
Carbon Dioxide Concentration ◽  
Marine Phytoplankton ◽  
Surface Ocean ◽  
Phytoplankton Communities ◽  
Co2 Levels ◽  
Asterionellopsis Glacialis

Abstract. Emissions of greenhouse gases, such as carbon dioxide (CO2), are lead to increasing global and surface ocean temperatures. At the same time, as CO2 equilibrates between the atmosphere and the surface ocean, it decreases sea water pH. As a result, the changes in physical and chemical properties of the ocean can affect marine primary producers in various ways. A number of researches have addressed the effects of ocean acidification on marine phytoplankton. However, phytoplankton responses to combined effects are still poorly understood. Here, we chose monospecific cultures of the cosmopolitan chain forming diatom Asterionellopsis glacialis (A. glacialis), grown semi-continuously under controlled laboratory conditions, to assess the combined effect of ocean acidification (~ 420 to 2800 µatm) and turbulence. At current CO2 levels, growth rates of A. glacialis increased under enhanced turbulence. This was the result of an optimum shift towards lower CO2 concentrations and accompanied by a prevalence of longer chains (more than 6 cells). For increasing CO2 levels (up to ~ 2800 µatm) and decreased pH values, enhanced turbulence significantly decreased growth rates, chain length and organic matter production of A. glacialis. Thus, our study suggests that, even though A. glacialis benefited from enhanced turbulence, at present carbon dioxide concentration, at higher CO2 levels, turbulence magnified the stress by acidification. If in the future, the ocean surface layer will be more frequently exposed to storm and wind events, then phytoplankton communities might be more sensitive to lower pH, with potential consequences for community composition and productivity.

scholarly journals Oceanic phytoplankton are a potentially important source of benzenoids to the remote marine atmosphere

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Manon Rocco ◽  
Erin Dunne ◽  
Maija Peltola ◽  
Neill Barr ◽  
Jonathan Williams ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dimethyl Sulfide ◽  
Laboratory Culture ◽  
Marine Phytoplankton ◽  
Marine Atmosphere ◽  
Aerosol Formation ◽  
Incubation Experiments ◽  
Phytoplankton Communities ◽  
Anthropogenic Air Pollutants ◽  
Benzene Toluene

AbstractBenzene, toluene, ethylbenzene and xylenes can contribute to hydroxyl reactivity and secondary aerosol formation in the atmosphere. These aromatic hydrocarbons are typically classified as anthropogenic air pollutants, but there is growing evidence of biogenic sources, such as emissions from plants and phytoplankton. Here we use a series of shipborne measurements of the remote marine atmosphere, seawater mesocosm incubation experiments and phytoplankton laboratory cultures to investigate potential marine biogenic sources of these compounds in the oceanic atmosphere. Laboratory culture experiments confirmed marine phytoplankton are a source of benzene, toluene, ethylbenzene, xylenes and in mesocosm experiments their sea-air fluxes varied between seawater samples containing differing phytoplankton communities. These fluxes were of a similar magnitude or greater than the fluxes of dimethyl sulfide, which is considered to be the key reactive organic species in the marine atmosphere. Benzene, toluene, ethylbenzene, xylenes fluxes were observed to increase under elevated headspace ozone concentration in the mesocosm incubation experiments, indicating that phytoplankton produce these compounds in response to oxidative stress. Our findings suggest that biogenic sources of these gases may be sufficiently strong to influence atmospheric chemistry in some remote ocean regions.

scholarly journals Experimental reef communities persist under future ocean acidification and warming

2021 ◽  
Author(s):  
Christopher Jury ◽  
Keisha Bahr ◽  
Evan Barba ◽  
Russell Brainard ◽  
Annick Cros ◽  
...  
Keyword(s):  
Experimental Study ◽  
Species Richness ◽  
Coral Reef ◽  
Coral Reefs ◽  
Ocean Acidification ◽  
Community Composition ◽  
Functional State ◽  
Reef Communities ◽  
Paris Climate Agreement

Abstract Coral reefs are among the most sensitive ecosystems affected by ocean acidification and warming, and are predicted to shift from net accreting calcifier-dominated systems to net eroding algal-dominated systems over the coming decades. Here we present a long-term experimental study examining the responses of entire mesocosm coral reef communities to acidification (-0.2 pH units), warming (+ 2°C), and combined future ocean (-0.2 pH, + 2°C) treatments. We show that under future ocean conditions, net calcification rates declined yet remained positive, corals showed reduced abundance yet were not extirpated, and community composition shifted while species richness was maintained. Our results suggest that under Paris Climate Agreement targets, coral reefs could persist in an altered functional state rather than collapse.

scholarly journals Diversity of dinoflagellate assemblages in coastal temperate and offshore tropical waters of Australia

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Tahnee Manning ◽  
Arjun Venkatesh Thilagaraj ◽  
Dmitri Mouradov ◽  
Richard Piola ◽  
Clare Grandison ◽  
...  
Keyword(s):  
Dissolved Oxygen ◽  
High Throughput ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
High Throughput Sequencing ◽  
Environmental Parameters ◽  
Marine Phytoplankton ◽  
Tropical Waters ◽  
Total Sequence ◽  
Phytoplankton Communities

Abstract Background Dinoflagellates are a ubiquitous and ecologically important component of marine phytoplankton communities, with particularly notable species including those associated with harmful algal blooms (HABs) and those that bioluminesce. High-throughput sequencing offers a novel approach compared to traditional microscopy for determining species assemblages and distributions of dinoflagellates, which are poorly known especially in Australian waters. Results We assessed the composition of dinoflagellate assemblages in two Australian locations: coastal temperate Port Phillip Bay and offshore tropical waters of Davies Reef (Great Barrier Reef). These locations differ in certain environmental parameters reflecting latitude as well as possible anthropogenic influences. Molecular taxonomic assessment revealed more species than traditional microscopy, and it showed statistically significant differences in dinoflagellate assemblages between locations. Bioluminescent species and known associates of HABs were present at both sites. Dinoflagellates in both areas were mainly represented by the order Gymnodiniales (66%—82% of total sequence reads). In the warm waters of Davies Reef, Gymnodiniales were equally represented by the two superclades, Gymnodiniales sensu stricto (33%) and Gyrodinium (34%). In contrast, in cooler waters of Port Phillip Bay, Gymnodiniales was mainly represented by Gyrodinium (82%). In both locations, bioluminescent dinoflagellates represented up to 0.24% of the total sequence reads, with Protoperidinium the most abundant genus. HAB-related species, mainly represented by Gyrodinium, were more abundant in Port Phillip Bay (up to 47%) than at Davies Reef (28%), potentially reflecting anthropogenic influence from highly populated and industrial areas surrounding the bay. The entire assemblage of dinoflagellates, as well as the subsets of HAB and bioluminescent species, were strongly correlated with water quality parameters (R2 = 0.56–0.92). Significant predictors differed between the subsets: HAB assemblages were explained by salinity, temperature, dissolved oxygen, and total dissolved solids; whereas, bioluminescent assemblages were explained only by salinity and dissolved oxygen, and had greater variability. Conclusion High-throughput sequencing and genotyping revealed greater diversity of dinoflagellate assemblages than previously known in both subtropical and temperate Australian waters. Significant correlations of assemblage structure with environmental variables suggest the potential for explaining the distribution and composition of both HAB species and bioluminescent species.

Nutrient-related selection mechanisms in marine phytoplankton communities and the impact of eutrophication on the planktonic food web

1995 ◽  
Vol 32 (4) ◽  
pp. 63-75 ◽  
Author(s):  
R. Riegman
Keyword(s):  
Algal Blooms ◽  
Algal Biomass ◽  
Resource Competition ◽  
Water Quality Management ◽  
Algal Species ◽  
Marine Phytoplankton ◽  
Commercial Fish ◽  
N Limitation ◽  
Phytoplankton Communities ◽  
The Impact

A general increase in nutrient discharges during the last few decades has caused various changes in the algal community structure along the European continental coast. Coincidentally and maybe consequently, the foodweb structure and functioning has altered in local areas causing various phenomena like oxygen depletion, mortality of groups of organisms, foam on beaches, and an increase in the productivity of benthic communities and some commercial fish species. The observed increases in algal biomass and shifts in species composition are discussed in relation to the involved key mechanisms: resource competition and selective grazing. Along the Dutch coastal zone of the North Sea eutrophication has caused a doubling of the yearly averaged algal biomass during the past three decades. The sudden appearance of Phaeocystis summer blooms coincided with a shift from P-limitation towards N-limitation in the Dutch coastal area due to a stronger increase in P-discharge relative to the increase in N-discharge. Competition experiments in continuous cultures showed Phaeocystis to become dominant under N-limitation. Additionally, the large Phaeocystis colonies, which can reach a diameter up to one centimetre, escape from microzooplankton grazing. A computer model is presented which demonstrates a shift from bottom-up towards top-down control if the pelagic environment becomes eutrophicated. Implementation of this concept in a size-differential phytoplankton control model generates the prediction that algal blooms are dominated by species that escape from grazing by those zooplankton species which have a high potential numerical response. In marine environments these are microzooplankton species. These organisms mainly feed on cyanobacteria, prochlorophytes and some nano-algal species. One of the consequences for foodweb structure and the carbon fluxes in marine foodwebs is that eutrophication will lead to the dominance of poorly edible algal species. Eutrophication favours the downward transport of carbon and nutrients towards the sediments not only due to higher algal biomasses but also as a consequence of a shift towards larger algal species with higher sedimentation characteristics. An example is given how these new insights can be used for water quality management purposes.

scholarly journals A Perspective on Body Size and Abundance Relationships across Ecological Communities

Biology ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 42
Author(s):  
Vojsava Gjoni ◽  
Douglas Stewart Glazier
Keyword(s):  
Body Size ◽  
Ecological Factors ◽  
Trophic Levels ◽  
Marine Phytoplankton ◽  
Published Data ◽  
Scaling Exponent ◽  
Ecological Communities ◽  
Macroinvertebrate Communities ◽  
Power Functions ◽  
Phytoplankton Communities

Recently, several studies have reported relationships between the abundance of organisms in an ecological community and their mean body size (called cross-community scaling relationships: CCSRs) that can be described by simple power functions. A primary focus of these studies has been on the scaling exponent (slope) and whether it approximates −3/4, as predicted by Damuth’s rule and the metabolic theory in ecology. However, some CCSR studies have reported scaling exponents significantly different from the theoretical value of −3/4. Why this variation occurs is still largely unknown. The purpose of our commentary is to show the value of examining both the slopes and elevations of CCSRs and how various ecological factors may affect them. As a heuristic exercise, we reanalyzed three published data sets based on phytoplankton, rodent, and macroinvertebrate assemblages that we subdivided according to three distinctly different ecological factors (i.e., climate zone, season, and trophic level). Our analyses reveal significant variation in either or both the CCSR slopes and elevations for marine phytoplankton communities across climate zones, a desert rodent community across seasons, and saltwater lagoon macroinvertebrate communities across trophic levels. We conclude that achieving a comprehensive understanding of abundance-size relationships at the community level will require consideration of both slopes and elevations of these relationships and their possible variation in different ecological contexts.

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