Posts Tagged 'vents'

Microbial strains isolated from CO2-venting Kolumbo submarine volcano show enhanced co-tolerance to acidity and antibiotics

Highlights

• The study investigates the effects of volcanic acidification to marine bacteria.

• Deep waters of Kolumbo submarine volcano are CO2-rich and more acidic.

• Pseudomonas strains from Kolumbo seafloor show higher tolerance to acidity.

• Strong correlation between acid and antibiotic tolerance of Pseudomonas species.

• Ocean acidification may lead to marine bacteria with increased antibiotic tolerance.

Abstract

As ocean acidification intensifies, there is growing global concern about the impacts that future pH levels are likely to have on marine life and ecosystems. By analogy, a steep decrease of seawater pH with depth is encountered inside the Kolumbo submarine volcano (northeast Santorini) as a result of natural CO2 venting, making this system ideal for ocean acidification research. Here, we investigated whether the increase of acidity towards deeper layers of Kolumbo crater had any effect on relevant phenotypic traits of bacterial isolates. A total of 31 Pseudomonas strains were isolated from both surface- (SSL) and deep-seawater layers (DSL), with the latter presenting a significantly higher acid tolerance. In particular, the DSL strains were able to cope with H+ levels that were 18 times higher. Similarly, the DSL isolates exhibited a significantly higher tolerance than SSL strains against six commonly used antibiotics and As(III). More importantly, a significant positive correlation was revealed between antibiotics and acid tolerance across the entire set of SSL and DSL isolates. Our findings imply that Pseudomonas species with higher resilience to antibiotics could be favored by the prospect of acidifying oceans. Further studies are required to determine if this feature is universal across marine bacteria and to assess potential ecological impacts.

Continue reading ‘Microbial strains isolated from CO2-venting Kolumbo submarine volcano show enhanced co-tolerance to acidity and antibiotics’

The carbon dioxide vents of Ischia, Italy, a natural system to assess impacts of ocean acidification on marine ecosystems: an overview of research and comparisons with other vent systems

As the ocean continues to take up carbon dioxide (CO2), it is difficult to predict the future of marine ecosystems. Natural CO2 vent sites, mainly of volcanic origin, that provide a pH gradient are useful as a proxy to investigate ecological effects of ocean acidification.

Continue reading ‘The carbon dioxide vents of Ischia, Italy, a natural system to assess impacts of ocean acidification on marine ecosystems: an overview of research and comparisons with other vent systems’

Low and variable pH decreases recruitment efficiency in populations of a temperate coral naturally present at a CO2 vent

Atmospheric carbon dioxide enrichment alters seawater carbonate chemistry, thus threatening calcifying organisms such as corals. Coral populations at carbon dioxide vents are natural acidification experiments that mimic organism responses to seawater pH values projected for 2100. Even if demographic traits are paramount information to assess ecological relationships and habitat suitability, population dynamics studies on corals thriving under acidified conditions are lacking. Here, we investigate the demography and reproduction of populations of the solitary, symbiotic, temperate coral Balanophyllia europaea naturally living along a pH gradient at a Mediterranean CO2 vent. Gametogenesis and larval production were unaffected while recruitment efficiency collapsed at low and variable pH, contributing to coral abundance decline and suggesting that life stages between larval release and early polyp growth are hindered by acidification. Exploring these processes is crucial to assess coral fate in the forthcoming acidified oceans, to preserve coral ecosystems and the socioeconomic services they provide.

Continue reading ‘Low and variable pH decreases recruitment efficiency in populations of a temperate coral naturally present at a CO2 vent’

Functional biodiversity loss along natural CO2 gradients

The effects of environmental change on biodiversity are still poorly understood. In particular, the consequences of shifts in species composition for marine ecosystem function are largely unknown. Here we assess the loss of functional diversity, i.e. the range of species biological traits, in benthic marine communities exposed to ocean acidification (OA) by using natural CO2 vent systems. We found that functional richness is greatly reduced with acidification, and that functional loss is more pronounced than the corresponding decrease in taxonomic diversity. In acidified conditions, most organisms accounted for a few functional entities (i.e. unique combination of functional traits), resulting in low functional redundancy. These results suggest that functional richness is not buffered by functional redundancy under OA, even in highly diverse assemblages, such as rocky benthic communities.

Continue reading ‘Functional biodiversity loss along natural CO2 gradients’

Characterization of bacterioplankton communities and quantification of organic carbon pools off the Galapagos Archipelago under contrasting environmental conditions

Bacteria play a crucial role in the marine carbon cycle, contributing to the production and degradation of organic carbon. Here, we investigated organic carbon pools, aggregate formation, and bacterioplankton communities in three contrasting oceanographic settings in the Galapagos Archipelago. We studied a submarine CO2 vent at Roca Redonda (RoR), an upwelling site at Bolivar Channel (BoC) subjected to a weak El Niño event at the time of sampling in October 2014, as well as a site without volcanic or upwelling influence at Cowley Islet (CoI). We recorded physico-chemical parameters, and quantified particulate and dissolved organic carbon, transparent exopolymeric particles, and the potential of the water to form larger marine aggregates. Free-living and particle-attached bacterial communities were assessed via 16S rRNA gene sequencing. Both RoR and BoC exhibited temperatures elevated by 1–1.5 °C compared to CoI. RoR further experienced reduced pH between 6.8 and 7.4. We observed pronounced differences in organic carbon pools at each of the three sites, with highest dissolved organic carbon concentrations at BoC and RoR, and highest particulate organic carbon concentrations and aggregate formation at BoC. Bacterioplankton communities at BoC were dominated by opportunistic copiotrophic taxa, such as Alteromonas and Roseobacter, known to thrive in phytoplankton blooms, as opposed to oligotrophic taxa dominating at CoI, such as members of the SAR11 clade. Therefore, we propose that bacterial communities were mainly influenced by the availability of organic carbon at the investigated sites. Our study provides a comprehensive characterization of organic carbon pools and bacterioplankton communities, highlighting the high heterogeneity of various components of the marine carbon cycle around the Galapagos Archipelago.

Continue reading ‘Characterization of bacterioplankton communities and quantification of organic carbon pools off the Galapagos Archipelago under contrasting environmental conditions’

Suitability of the shallow water hydrothermal system at Ambitle Island (Papua New Guinea) to study the effect of high pCO2 on coral reefs

Highlights

• Volcanic CO2vents and seeps acidify Tutum Bay
• HCorals survive at pH levels lower than climate change projected levels for the end of this century
• Hydrothermal vents in Tutum Bay are enriched in some metals, but concentrations are quickly diluted by mixing with seawater
• Surface water was enriched in arsenic and silica, although reef values were found to be lower

Abstract

Volcanic CO2 seeps were successfully used to predict coral reef response to ocean acidification, although toxic elements, often characteristic of hydrothermal vents were rarely reported. We measured the physicochemical conditions, seawater carbonate chemistry and trace elements in Tutum Bay, Papua New Guinea. There, intense emission of hydrothermal fluids and CO2 expose the coral reef to a seawater pHT between 7.6 and 7.7.
Arsenic and silica were enriched by up to six times in surface seawater, while bottom concentrations were lower and thus similar to coral reefs worldwide. Manganese, cesium, iron and zinc concentrations fell into the range of other coastal environments. Our measurements suggest that Tutum Bay is a suitable site to study the response of coral reefs to high pCO2. Considering that arsenic is a common metal in hydrothermal fluids, its characterization should be included in any study that uses volcanic CO2 seeps as natural laboratories for ocean acidification.

Continue reading ‘Suitability of the shallow water hydrothermal system at Ambitle Island (Papua New Guinea) to study the effect of high pCO2 on coral reefs’

Water circulation, and not ocean acidification, affects coral recruitment and survival at shallow hydrothermal vents

Highlights

• Coral recruitment and survival are not affected by water acidification.
• Recruits’ abundance is enhanced in vent sites compare to control sites.
• Hydrothermal vent cause a closed water circulation.
• Vent activity promote coral recruitment by retaining coral larvae.
• Broadcast-spawning corals, Acropora and most of the Others, seem to be favoured.

Abstract

Shallow hydrothermal vents emit warm water, carbon dioxide, toxic chemicals, nutrients and reduced compounds that altogether mimic climate and human impacts, and are therefore considered as ‘natural laboratories’ at which can be investigated the effects of these stressors on marine ecosystems. One of the effects more thoroughly investigated is the impact of reduced pH on marine biodiversity. Calcifying organisms, such as corals, are expected to be more affected, but their response to reduced pH values in seawater has been tackled mostly by laboratory studies. Here, we assessed coral recruitment and juvenile survival, two fundamental processes for coral reef maintenance and resilience, in shallow reefs of North Sulawesi (Indonesia) close to hydrothermal vents. Differences in abundance of coral recruits (<5 cm in diameter) and juveniles (5–15 cm in diameter) were evaluated at vent sites and at control sites, on both reef flats and upper slopes. Recruits of Acropora and other broadcasting corals resulted more abundant near vents, while no difference in juvenile survival was observed between vent sites and controls. On the contrary, Pocillopora, which includes many brooders, showed a low density of recruits and low survival rates at vent sites. Vents caused a typical closed water circulation that retained coral larvae on site, and this effect, rather than water acidification or the emission of chemical compounds, was likely to be responsible for increased recruitment of broadcasters.

Continue reading ‘Water circulation, and not ocean acidification, affects coral recruitment and survival at shallow hydrothermal vents’


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