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Rousselaki E, Michalopoulos P, Pavlidou A, Kaberi H, Prifti E, Dassenakis M. Pore-water nutrient concentrations variability under different oxygen regimes: A case study in Elefsis Bay, Greece. Sci Total Environ 2024; 915:169830. [PMID: 38190920 DOI: 10.1016/j.scitotenv.2023.169830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2023] [Revised: 12/29/2023] [Accepted: 12/30/2023] [Indexed: 01/10/2024]
Abstract
Anthropogenic pressures considerably affect coastal areas, increasing nitrogen and phosphorous loads that lead to eutrophication. Eutrophication sometimes results in hypoxic and/or anoxic conditions near the bottom water. Dissolved oxygen (DO) concentrations influence redox-sensitive nutrients, which can alter the benthic flux of nutrients. We retrieved sediment cores from two sites in the eastern and western parts of Elefsis Bay, a semi-enclosed area of the Eastern Mediterranean, Greece, during winter and summer. In the western part, seasonally hypoxic or anoxic conditions occurred. We analysed pore-water samples under normoxic, hypoxic and anoxic bottom water conditions to study the pore-water nutrient concentrations variability under different oxygen regimes. Ex situ incubation experiments were conducted at the site experiencing oxygen deficiency by manipulating the DO concentrations. The pore-water nutrient concentrations showed higher variability at the site experiencing oxygen deficiency. Notably, elevated ammonium concentrations were observed in the pore water during anoxic conditions, in the 2-20-cm sediment layer. However, the benthic fluxes of ammonium and phosphate at the 0-2-cm sediment layer were comparable under hypoxic and anoxic conditions. The results of the incubation experiments demonstrate a direct decrease in nitrate concentrations as the DO concentrations diminished in the overlying water. The incubations after re-oxygenating the overlying water show that phosphate was more efficiently scavenged when anoxic conditions prevailed in the bottom water. The incubation experiments indicate the rapid response of the seafloor to oxygen availability, particularly concerning processes that influence nitrate and phosphate concentrations. These observations highlight the dynamic nature of nutrient cycling in shallow, seasonally anoxic environments, such as Elefsis Bay, and emphasise the sensitivity of the seafloor ecosystem to changes in bottom water oxygen availability.
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Affiliation(s)
- Eleni Rousselaki
- Institute of Oceanography, Hellenic Centre for Marine Research, Anavyssos, Greece.
| | | | - Alexandra Pavlidou
- Institute of Oceanography, Hellenic Centre for Marine Research, Anavyssos, Greece
| | - Helen Kaberi
- Institute of Oceanography, Hellenic Centre for Marine Research, Anavyssos, Greece
| | - Eleni Prifti
- Institute of Oceanography, Hellenic Centre for Marine Research, Anavyssos, Greece
| | - Manos Dassenakis
- Laboratory of Environmental Chemistry, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimioupolis, Athens, Greece
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Schroeder K, Kovačević V, Civitarese G, Velaoras D, Álvarez M, Tanhua T, Jullion L, Coppola L, Bensi M, Ursella L, Santinelli C, Giani M, Chiggiato J, Aly-Eldeen M, Assimakopoulou G, Bachi G, Bogner B, Borghini M, Cardin V, Cornec M, Giannakourou A, Giannoudi L, Gogou A, Golbol M, Hazan O, Karthäuser C, Kralj M, Krasakopoulou E, Matić F, Mihanović H, Muslim S, Papadopoulos VP, Parinos C, Paulitschke A, Pavlidou A, Pitta E, Protopapa M, Rahav E, Raveh O, Renieris P, Reyes-Suarez NC, Rousselaki E, Silverman J, Souvermezoglou E, Urbini L, Zeri C, Zervoudaki S. Seawater physics and chemistry along the Med-SHIP transects in the Mediterranean Sea in 2016. Sci Data 2024; 11:52. [PMID: 38195581 PMCID: PMC10776779 DOI: 10.1038/s41597-023-02835-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2023] [Accepted: 12/08/2023] [Indexed: 01/11/2024] Open
Abstract
The Mediterranean Sea has been sampled irregularly by research vessels in the past, mostly by national expeditions in regional waters. To monitor the hydrographic, biogeochemical and circulation changes in the Mediterranean Sea, a systematic repeat oceanographic survey programme called Med-SHIP was recommended by the Mediterranean Science Commission (CIESM) in 2011, as part of the Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP). Med-SHIP consists of zonal and meridional surveys with different frequencies, where comprehensive physical and biogeochemical properties are measured with the highest international standards. The first zonal survey was done in 2011 and repeated in 2018. In addition, a network of meridional (and other key) hydrographic sections were designed: the first cycle of these sections was completed in 2016, with three cruises funded by the EU project EUROFLEETS2. This paper presents the physical and chemical data of the meridional and key transects in the Western and Eastern Mediterranean Sea collected during those cruises.
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Affiliation(s)
- Katrin Schroeder
- Consiglio Nazionale delle Ricerche-Istituto di Scienze Marine (CNR-ISMAR), Venice and La Spezia, Italy.
| | - Vedrana Kovačević
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - Giuseppe Civitarese
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - Dimitris Velaoras
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Marta Álvarez
- Instituto Español de Oceanografía, IEO-CSIC, A Coruña, Spain
| | - Toste Tanhua
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | | | - Laurent Coppola
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-Mer, France
- Sorbonne Université, CNRS, OSU STAMAR, UAR2017, 4 Place Jussieu, 75252, Paris, cedex, 05, France
| | - Manuel Bensi
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - Laura Ursella
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - Chiara Santinelli
- Consiglio Nazionale delle Ricerche-Istituto di Biofisica (CNR-IBF), Pisa, Italy
| | - Michele Giani
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - Jacopo Chiggiato
- Consiglio Nazionale delle Ricerche-Istituto di Scienze Marine (CNR-ISMAR), Venice and La Spezia, Italy
| | | | | | - Giancarlo Bachi
- Consiglio Nazionale delle Ricerche-Istituto di Biofisica (CNR-IBF), Pisa, Italy
| | - Boie Bogner
- GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany
| | - Mireno Borghini
- Consiglio Nazionale delle Ricerche-Istituto di Scienze Marine (CNR-ISMAR), Venice and La Spezia, Italy
| | - Vanessa Cardin
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - Marin Cornec
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-Mer, France
| | - Antonia Giannakourou
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Louisa Giannoudi
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Alexandra Gogou
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Melek Golbol
- Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, Villefranche-sur-Mer, France
| | - Or Hazan
- Israel Oceanographic and Limnological Research, IOLR, Haifa, Israel
| | | | - Martina Kralj
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | | | - Frano Matić
- University Department of Marine Studies, University of Split, Split, Croatia
| | | | - Stipe Muslim
- University Department of Marine Studies, University of Split, Split, Croatia
| | | | - Constantine Parinos
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | | | - Alexandra Pavlidou
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Elli Pitta
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Maria Protopapa
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Eyal Rahav
- Israel Oceanographic and Limnological Research, IOLR, Haifa, Israel
| | - Ofrat Raveh
- Israel Oceanographic and Limnological Research, IOLR, Haifa, Israel
| | - Panagiotis Renieris
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | | | - Eleni Rousselaki
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Jacop Silverman
- Israel Oceanographic and Limnological Research, IOLR, Haifa, Israel
| | | | - Lidia Urbini
- National Institute of Oceanography and Applied Geophysics - OGS, Trieste, Italy
| | - Christina Zeri
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
| | - Soultana Zervoudaki
- Hellenic Centre for Marine Research, HCMR, Institute of Oceanography, Anavyssos, Greece
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Kontoyiannis H, Pavlidou A, Zeri C, Krasakopoulou E, Simboura N, Hatzianestis I, Papadopoulos VP, Rousselaki E, Asimakopoulou G, Siokou I. Thirty years of a bottom oxygen depletion-renewal cycle in the coastal yet deep environment of the West Saronikos Gulf (Greece): Its drivers and the impact on the benthic communities. Sci Total Environ 2023; 902:166025. [PMID: 37562620 DOI: 10.1016/j.scitotenv.2023.166025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/01/2023] [Accepted: 08/01/2023] [Indexed: 08/12/2023]
Abstract
In the period 1987-2017, a series of physical and chemical measurements related to oxygen variability at a trough area with a maximum depth of ~420 m in the West Saronikos Gulf, reveal the following: In the early 90s, deep winter mixing occurred resulting in an oxygenation down to ~420 m followed by an oxygen decline. This decline reached near-bottom hypoxic conditions (O2 < ~62 μM (μmol/L)) after 1998, while a denitrification phase occurred after 2000 and a complete bottom anoxia in 2005. In June 2012, an oxygenation down to ~350 m was detected that most likely occurred in winter 2012. The 2012 oxygenation raised the until-then anoxic bottom concentrations to hypoxic ones in the years towards 2017 via vertical diffusive oxygen transfer. Observations of the benthic communities during the hypoxia, severe hypoxia (O2 < ~15 μM) and oxygen recovery phases showed a peak of opportunists in the hypoxia and a long faunal depletion in the severe hypoxia phases. A reversal in the benthic community structure appeared after the oxygenation of 2012 with the (re)appearance of opportunists while, in 2017, the community showed signs of retreat to earlier stages. The main anthropogenic pressure that could tentatively affect the oxygen concentration in the study area is posed by the Athens treated-sewage outfall at ~40 km away from the trough, which inputs organic matter into the Saronikos Gulf through effluent water of reduced salinity that, in addition, may alter the stratification opposing the vertical mixing. We show that the treated sewage output had no influence on a) the stratification, b) the particulate and dissolved organic carbon and c) the sewage-derived organic matter. Instead, the long-term dissolved oxygen variability with the deep renewal events was mostly driven by the large-scale atmosphere-ocean conditions (heat exchange and evaporation-minus-precipitation budget) that determine the hydrographic characteristics and the winter mixing.
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Affiliation(s)
| | - Alexandra Pavlidou
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece.
| | - Christina Zeri
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece
| | | | - Nomiki Simboura
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece
| | - Ioannis Hatzianestis
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece
| | | | - Eleni Rousselaki
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece
| | | | - Ioanna Siokou
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, Greece
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Pavlidou A, Anastasopoulou E, Dassenakis Μ, Hatzianestis I, Paraskevopoulou V, Simboura N, Rousselaki E, Drakopoulou P. Effects of olive oil wastes on river basins and an oligotrophic coastal marine ecosystem: a case study in Greece. Sci Total Environ 2014; 497-498:38-49. [PMID: 25112823 DOI: 10.1016/j.scitotenv.2014.07.088] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 07/11/2014] [Accepted: 07/11/2014] [Indexed: 06/03/2023]
Abstract
This work aims to contribute to the knowledge of the impacts of olive oil waste discharge to freshwater and oligotrophic marine environments, since the ecological impact of olive oil wastes in riverine and coastal marine ecosystems, which are the final repositories of the pollutants, is a great environmental problem on a global scale, mostly concerning all the Mediterranean countries with olive oil production. Messinia, in southwestern Greece, is one of the greatest olive oil production areas in Europe. During the last decade around 1.4×10(6)tons of olive oil mill wastewater has been disposed in the rivers of Messinia and finally entered the marine ecosystem of Messiniakos gulf. The pollution from olive oil mill wastewater in the main rivers of Messinia and the oligotrophic coastal zone of Messiniakos gulf and its effects on marine organisms were evaluated, before, during and after the olive oil production period. Elevated amounts of phenols (36.2-178 mg L(-1)) and high concentrations of ammonium (7.29-18.9 mmol L(-1)) and inorganic phosphorus (0.5-7.48 mmol L(-1)) were measured in small streams where the liquid disposals from several olive oil industries were gathered before their discharge in the major rivers of Messinia. The large number of olive oil units has downgraded the riverine and marine ecosystems during the productive period and a period more than five months is needed for the recovery of the ecosystem. Statistical analysis showed that the enrichment of freshwater and the coastal zone of Messiniakos gulf in ammonia, nitrite, phenols, total organic carbon, copper, manganese and nickel was directly correlated with the wastes from olive oil. Toxicity tests using 24h LC50 Palaemonidae shrimp confirm that olive mill wastewater possesses very high toxicity in the aquatic environment.
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Affiliation(s)
- A Pavlidou
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, 19013, Greece.
| | - E Anastasopoulou
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, 19013, Greece
| | - Μ Dassenakis
- Laboratory of Environmental Chemistry, Department of Chemistry, National Kapodistrian University of Athens, Zografou, Panepistimiopolis, 15771 Athens, Greece
| | - I Hatzianestis
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, 19013, Greece
| | - V Paraskevopoulou
- Laboratory of Environmental Chemistry, Department of Chemistry, National Kapodistrian University of Athens, Zografou, Panepistimiopolis, 15771 Athens, Greece
| | - N Simboura
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, 19013, Greece
| | - E Rousselaki
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, 19013, Greece
| | - P Drakopoulou
- Hellenic Centre for Marine Research, Institute of Oceanography, Anavyssos, 19013, Greece
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