Increasing atmospheric CO2 concentrations are causing an alarming rise in pCO2 concentrations at the ocean surface, generating the well-known phenomenon of ‘Ocean Acidification’(OA). Recent studies in naturally acidified environments pointed out that benthic community structure and diversity might be altered by high pCO2 levels. For the present study, sediment samples were collected along a pH gradient (mean range 7.4-8.1) nearby the CO2 vents located on the northern and southern sides of Castello Aragonese (Ischia island, Italy), to characterize the meiobenthic community inhabiting the sediments of these naturally acidified environments. Total organic carbon (TOC) content and the grain size have been determined at each sampling station: N1, N2, N3 on the northern side; S1, S2, S3 on the southern side. We considered as a null hypothesis that there would be no significant difference in meiobenthic community abundance and composition along the pH gradients investigated. Overall, major differences were observed between intermediate stations (N2 and S2) vs. acidified (N3 and S3) and control stations (N1 and S1). The meiobenthic diversity seemed not particularly affected by lower pH conditions, while the lowest abundance value (167±75 ind/10cm2 at station N2) did not characterize the most acidified stations (S3 and N3). Among the total of 16 taxa identified, the most abundant were Nematoda, Copepoda and their nauplii at all sampling stations. The total contribution of rare taxa (i.e. taxa <1% of total meiofaunal abundance) ranged from 1% (N2) to 2.6% (S3). Significant changes in meiobenthic community composition were detected between stations located both on the northern and southern sides of Castello, particularly, when only rare taxa were considered (dissimilarity ranging from 51% to 96% at S3 vs. S1 and N3 vs. N2, respectively). The pH conditions appeared to be a secondary factor that governed meiofauna distribution and variability among stations at the Castello vents, with respect to grain size and food availiability, which seemed more important. Although in this study case the meiofauna was not strongly affected by acidified conditions, an overall continuous increase of marine CO2 levels could result in a changed functional diversity. The study of the nematode taxonomic and functional composition (in progress) will help in exploring the issue. This study aims to advance our understanding of how marine benthic communities may react to OA.

First insight into meiofauna inhabiting the shallow CO2 -seeps around Castello Aragonese (Ischia, Italy).

Grassi E.;Semprucci F.
2022

Abstract

Increasing atmospheric CO2 concentrations are causing an alarming rise in pCO2 concentrations at the ocean surface, generating the well-known phenomenon of ‘Ocean Acidification’(OA). Recent studies in naturally acidified environments pointed out that benthic community structure and diversity might be altered by high pCO2 levels. For the present study, sediment samples were collected along a pH gradient (mean range 7.4-8.1) nearby the CO2 vents located on the northern and southern sides of Castello Aragonese (Ischia island, Italy), to characterize the meiobenthic community inhabiting the sediments of these naturally acidified environments. Total organic carbon (TOC) content and the grain size have been determined at each sampling station: N1, N2, N3 on the northern side; S1, S2, S3 on the southern side. We considered as a null hypothesis that there would be no significant difference in meiobenthic community abundance and composition along the pH gradients investigated. Overall, major differences were observed between intermediate stations (N2 and S2) vs. acidified (N3 and S3) and control stations (N1 and S1). The meiobenthic diversity seemed not particularly affected by lower pH conditions, while the lowest abundance value (167±75 ind/10cm2 at station N2) did not characterize the most acidified stations (S3 and N3). Among the total of 16 taxa identified, the most abundant were Nematoda, Copepoda and their nauplii at all sampling stations. The total contribution of rare taxa (i.e. taxa <1% of total meiofaunal abundance) ranged from 1% (N2) to 2.6% (S3). Significant changes in meiobenthic community composition were detected between stations located both on the northern and southern sides of Castello, particularly, when only rare taxa were considered (dissimilarity ranging from 51% to 96% at S3 vs. S1 and N3 vs. N2, respectively). The pH conditions appeared to be a secondary factor that governed meiofauna distribution and variability among stations at the Castello vents, with respect to grain size and food availiability, which seemed more important. Although in this study case the meiofauna was not strongly affected by acidified conditions, an overall continuous increase of marine CO2 levels could result in a changed functional diversity. The study of the nematode taxonomic and functional composition (in progress) will help in exploring the issue. This study aims to advance our understanding of how marine benthic communities may react to OA.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11576/2750392
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