Posts Tagged 'vents'

Impact of carbonate saturation on large Caribbean benthic foraminifera assemblages

Increasing atmospheric carbon dioxide and its dissolution in seawater have reduced ocean pH and carbonate ion concentration with potential implications to calcifying organisms. To assess the response of Caribbean benthic foraminifera to low carbonate saturation conditions, we analyzed benthic foraminifera abundance and relative distribution in proximity to low carbonate saturation submarine springs and at adjacent control sites. Our results show that the total abundance of benthic foraminifera is significantly lower at the low pH low calcite saturation submarine springs than at control sites, despite higher concentrations of inorganic carbon at the spring sites. The relative abundance of symbiont-bearing foraminifera and agglutinated foraminifera was higher at the low pH low calcite saturation submarine springs compared to control sites. These differences indicate that non-symbiont bearing heterotrophic calcareous foraminifera are more sensitive to the effects of ocean acidification than non-calcifying and symbiont bearing foraminifera, suggesting that future ocean acidification may impact natural benthic foraminifera populations.

Continue reading ‘Impact of carbonate saturation on large Caribbean benthic foraminifera assemblages’

Coccolithophore community response along a natural CO2 gradient off Methana (SW Saronikos Gulf, Greece, NE Mediterranean)

A natural pH gradient caused by marine CO2 seeps off the Methana peninsula (Saronikos Gulf, eastern Peloponnese peninsula) was used as a natural laboratory to assess potential effects of ocean acidification on coccolithophores. Coccolithophore communities were therefore investigated in plankton samples collected during September 2011, September 2016 and March 2017. The recorded cell concentrations were up to ~50 x103 cells/l, with a high Shannon index of up to 2.8, along a pH gradient from 7.61 to 8.18, with values being occasionally <7. Numerous holococcolithophore species represented 60–90% of the surface water assemblages in most samples during September samplings. Emiliania huxleyi was present only in low relative abundances in September samples, but it dominated in March assemblages. Neither malformed nor corroded coccolithophores were documented. Changes in the community structure can possibly be related to increased temperatures, while the overall trend associates low pH values with high cell densities. Our preliminary results indicate that in long-termed acidified, warm and stratified conditions, the study of the total coccolithophore assemblage may prove useful to recognize the intercommunity variability, which favors the increment of lightly calcified species such as holococcolithophores.

Continue reading ‘Coccolithophore community response along a natural CO2 gradient off Methana (SW Saronikos Gulf, Greece, NE Mediterranean)’

CO2 emissions boost the benefits of crop production by farming damselfish

Farming is a technique employed by both humans and animals to enhance crop yields, allowing their populations to increase beyond the natural carrying capacity of the environment. Using volcanic CO2 vents, we investigate how a species of herbivorous fish (the black scalyfin Parma alboscapularis) may use increasing anthropogenic CO2 emissions to enhance its crop yields. We found that these farming fish can take advantage of this resource enrichment, to grow crops within smaller territories and increase the capacity of the environment to support more densely packed fish populations.

Continue reading ‘CO2 emissions boost the benefits of crop production by farming damselfish’

Marine hydrothermal vents as templates for global change scenarios

Subsurface marine hydrothermal vents (HVs) may provide a particular advantage to better understand evolutionary conditions of the early earth and future climate predictions for marine life. Hydrothermal vents (HV) are unique extreme environments that share several similarities with projected global and climate change scenarios in marine systems (e.g., low pH due to high carbon dioxide and sulfite compounds, high temperature and turbidity, high loads of toxic chemicals such as H2S and trace metals). Particularly, shallow hydrothermal vents are easily accessible for short-term and long-term experiments. Research on organisms from shallow HVs may provide insights in the molecular, ecological, and evolutionary adaptations to extreme oceanic environments by comparing them with evolutionary related but less adapted biota. A shallow-water hydrothermal vent system at the northeast Taiwan coast has been intensively studied by several international research teams. These studies revealed astounding highlights at the levels of ecosystem (being fueled by photosynthesis and chemosynthesis), community (striking biodiversity changes due to mass mortality), population (retarded growth characteristics), individual (habitat attractive behavior), and molecular (adaptations to elevated concentrations of heavy metals, low pH, and elevated temperature). The present opinion paper evaluates the potential of shallow hydrothermal vents to be used as a templates for global change scenarios.

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Effects of ocean acidification on the levels of primary and secondary metabolites in the brown macroalga Sargassum vulgare at different time scales

Highlights

Sargassum vulgare growing at CO2 vents was compared with those growing at control site.
S. vulgare from control site was transplanted to CO2 vents for 2 weeks.
• In short-term responses, S. vulgare showed increased level of sugars, PUFAs, and EAAs.
• Natural population at vents showed decreased sugars, PUFAs, phenols, and increased EAAs.
• Nutritional values of algae will decrease under acidification in long time scale.

Abstract

Most of the studies regarding the impact of ocean acidification on macroalgae have been carried out for short-term periods, in controlled laboratory conditions, thus hampering the possibility to scale up the effects on long-term. In the present study, the volcanic CO2 vents off Ischia Island were used as a natural laboratory to investigate the metabolic response of the brown alga Sargassum vulgare to acidification at different time scales. For long-term effects, algal populations naturally growing at acidified and control sites were compared. For short-term responses, in situ reciprocal transplants from control to acidified site and vice-versa were performed. Changes in the levels of sugars, fatty acids (FAs), amino acids (AAs), antioxidants, and phenolic compounds were examined. Our main finding includes variable metabolic response of this alga at different time scales to natural acidification. The levels of sugars, FAs, and some secondary metabolites were lower in the natural population at the acidified site, whereas the majority of AAs were higher than those detected in thalli growing at control site. Moreover, in algae transplanted from control to acidified site, soluble sugars (glucose and mannose), majority of AAs, and FAs increased in comparison to control plants transplanted within the same site. The differences in the response of the macroalga suggest that the metabolic changes observed in transplants may be due to acclimation that supports algae to cope with acidification, thus leading to adaptation to lowered pH in long time scale.

Graphical abstract

Unlabelled Image

Continue reading ‘Effects of ocean acidification on the levels of primary and secondary metabolites in the brown macroalga Sargassum vulgare at different time scales’

Ecophysiological response of Jania rubens (Corallinaceae) to ocean acidification

Coralline algae (Rhodophyta) play a key role in promoting settlement of other benthic organisms, being the food source for herbivores, being involved in the stabilization of reef networks, and in carbonate production. They are considered a vulnerable group to ocean acidification due to the potential dissolution of their high-Mg calcite skeleton at lower pH. Nevertheless, different species of coralline algae showed different responses to low-pH/high-pCO2 environment. Here, we studied the physiological response of Jania rubens to the pH condition predicted for the year 2100. We used a natural CO2 vent system as natural laboratory to transplant J. rubens from pH 8.1–7.5 for 3 weeks. Maximal PSII photochemical efficiency showed a significant reduction in transplanted thalli at low pH (7.5-T) compared to other conditions; consistent with that result, also the pigments involved in the light-harvesting spectrum of J. rubens (i.e., chlorophylls, carotenoids, and phycobilins), exhibited a significant decrease under water acidification, highlighting the strong sensitivity of this species to the environmental change. A major understanding of the response of coralline algae at high CO2 will go through the impact of OA on benthic ecosystems in the next future. This contribution is the written, peer-reviewed version of a paper presented at the Conference “Changes and Crises in the Mediterranean Sea” held at Accademia Nazionale dei Lincei in Rome on October 17, 2017.

Continue reading ‘Ecophysiological response of Jania rubens (Corallinaceae) to ocean acidification’

Composition and spatial distribution of the meiofauna in the Wagner and Consag basins, Gulf of California, Mexico

In this study, we analyse the horizontal and vertical distribution of the meiofauna in the Wagner and Consag basins. Samples were collected at soft bottom sites on board of the R/V “El Puma” (WAGNER-02 Expedition) during July- August 2010 with a Smith McIntyre grab and 10 cm cores. At each station physical and chemical variables were measured including depth, salinity, pore water temperature and pH. Twelve higher taxa of meiofauna were recorded in both basins. Meiofauna was dominated by Nematoda (73.1%) followed by Copepoda Harpacticoida (11.28%), Polychaeta (8.41%) and Kinorhyncha (4.71%). Density of meiofauna in these two basins ranked from 19.12 to 742.20 ind.10 cm-2 and were mainly concentrated in the first four centimeters of the sediment (78.6%) and decreased with sediment depth; PERMANOVA analysis show significant differences among sediment depth layers. However, PERMANOVA analysis did not show significant differences of the abundances of meiofauna between basins. Multivariate Correspondence Canonica l Analysis (MCCA) was performed but the assemblages identified had no spatial gradient. This only confirms the patchy distribution already reported for the meiofauna. This analysis reported two faunal groups: Nematoda -Polychaeta and Copepoda – Kinorhyncha. In the present study, we report for the first time the horizontal and vertical distribution of the meiofauna in a natural CO2 venting area in the Gulf of California. There is still so much that we do not know about meiofauna processes, more studies are needed specially down to species level in order to have a clearer view of how environmental factors affect each species spatial distribution.

Continue reading ‘Composition and spatial distribution of the meiofauna in the Wagner and Consag basins, Gulf of California, Mexico’


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Ocean acidification in the IPCC AR5 WG II

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