Circulation and water mass structure over a narrow shelf, Augusta Gulf (sicily)

Raffa, F.; Hopkins, Thomas S.

doi:10.1080/02757540410001699857

Cited by 14 publications

(4 citation statements)

References 11 publications

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“…Moreover, the common recovery of N. turgidus and V. bradyana suggests a muddy substratum rich in organic matter, consistent with intermediate depths (mid‐outer shelf), as highlighted in cores MG03 and MG04 and to a lesser extent in MG02. Notably, the often irregular distribution of cluster assemblages along the study sequence (Table ) point out that benthic foraminifera are sometimes affected by significant transport, probably due to bottom currents (Raffa & Hopkins, ), as highlighted by the widespread distribution of Ammonia spp. from the mid‐inner to the outer shelf.…”

Section: Discussionmentioning

confidence: 99%

“…The original environment was also modified over time by sediment dredging within the port and its relative settlement in both legal and illegal disposal offshore areas (Bellucci et al ., ). Thus, much of the literature is also focused on the effects of industrial activity and its relative contaminant influence on the coastal ecosystem as a whole (Decembrini et al ., ; Raffa & Hopkins, ), and especially on the living benthic foraminiferal communities based on data from shallow cores and box‐core stations within the harbour (Romano et al ., , , ; Bergamin & Romano, ), and from the outer shelf in the southern part of Augusta Bay (Di Leonardo et al ., ).…”

Section: Study Sitementioning

confidence: 99%

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New coring study in Augusta Bay expands understanding of offshore tsunami deposits (Eastern Sicily, Italy)

et al. 2019

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Tsunami deposits present an important archive for understanding tsunami histories and dynamics. Most research in this field has focused on onshore preserved remains, while the offshore deposits have received less attention. In 2009, during a coring campaign with the Italian Navy Magnaghi, four 1 m long gravity cores (MG cores) were sampled from the northern part of Augusta Bay, along a transect in 60 to 110 m water depth. These cores were taken in the same area where a core (MS06) was collected in 2007 about 2·3 km offshore Augusta at a water depth of 72 m below sea level. Core MS06 consisted of a 6·7 m long sequence that included 12 anomalous intervals interpreted as the primary effect of tsunami backwash waves in the last 4500 years. In this study, tsunami deposits were identified, based on sedimentology and displaced benthic foraminifera (as for core MS06) reinforced by X‐ray fluorescence data. Two erosional surfaces (L1 and L2) were recognized coupled with grain‐size increase, abundant Posidonia oceanica seagrass remains and a significant amount of Nubecularia lucifuga, an epiphytic sessile benthic foraminifera considered to be transported from the inner shelf. The occurrence of Ti/Ca and Ti/Sr increments, coinciding with peaks in organic matter (Mo incoherent/coherent) suggests terrestrial run‐off coupled with an input of organic matter. The L1 and L2 horizons were attributed to two distinct historical tsunamis (ad 1542 and ad 1693) by indirect age‐estimation methods using 210Pb profiles and the comparison of Volume Magnetic Susceptibility data between MG cores and MS06 cores. One most recent bioturbated horizon (Bh), despite not matching the above listed interpretative features, recorded an important palaeoenvironmental change that may correspond to the ad 1908 tsunami. These findings reinforce the value of offshore sediment records as an underutilized resource for the identification of past tsunamis.

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Section: Discussionmentioning

confidence: 99%

Section: Study Sitementioning

confidence: 99%

New coring study in Augusta Bay expands understanding of offshore tsunami deposits (Eastern Sicily, Italy)

et al. 2019

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“…As a formal model, the Straits of Messina may be compared to an 'intermittent pump', which compresses and nutrientenriches itself during the autumn and winter seasons, while in spring it releases and stimulates phytoplankton in both locally and adjacent zones (De Domenico et al, 1988;Azzaro et al, 1995;Magazzù et al, 1995;Decembrini et al, 1998;Kinder and Bryden, 1990). During the summer season, the surface water is enriched with nutrients and is advected to-wards the surrounding areas, where a decrease of nutrients and increase of chlorophyll−a occurs, namely in the north (Gulf of Gioia Tauro; Innamorati et al, 1996) and along the southeastern Sicilian coast (Böhm et al,1987;Decembrini et al, 2004;Raffa and Hopkins, 2004). In other marine ecosystems, low phytoplankton growth is due to nutrient depletion of the euphotic layer.…”

Section: Discussionmentioning

confidence: 99%

Seasonal variability of phytoplankton fluorescence in relation to the Straits of Messina (Sicily) tidal upwelling

Azzaro¹,

Decembrini²,

Raffa³

et al. 2007

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Abstract. In the Straits of Messina the large gradients of tidal displacements as well as the topographic constrictions determine the upwelling of deeper waters in the surface layer. This work describes the seasonal variability of surface distribution of phytoplankton biomass depending on upwelling phenomena. Temperature, salinity, nitrates and phytoplankton fluorescence were measured in 1994 and 1995 by continuous underway surface real-time measurements on board dedicated research boats. Each survey was performed following the dynamic phases of flooding and ebbing tides. Tidal currents are essentially southward during the high tide and northward during the low tide. During the low water slack, large spatial gradients of physical-chemical and biological parameters were mainly found, while in the high water slack a diffused phytoplankton fluorescence was observed only in autumn, in coincidence of a seasonal thermocline. Salinity, nitrate and chlorophyll-a fluorescence data revealed a significant positive intercorrelation, whereas they are inversely correlated with temperature. Generally, during winter, the upwelling distribution was limited to narrow zones, while in summer it involved the middle of the Straits and southern zones. During spring in the southern zone of the Straits, maximum of chlorophyll-a fluorescence was detected (May 1995, 0.32 µg-Chla l-1); in summer, when back and forth tidal movements become intense between the Tyrrhenian and the Ionian seas, values was everywhere lower. The data set from continuous and repeatable acquisition has allowed the study of different time-space scales in the Straits of Messina, a very strong dynamic environment. The Straits system can be compared to an "intermittent pump" which, during the different seasons, before enriched itself and then it provides nutrients to the surrounding basins.

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“…As a formal model, the Straits of Messina may be compared to an 'intermittent pump', which compresses and nutrientenriches itself during the autumn and winter seasons, while in spring it releases and stimulates phytoplankton in both locally and adjacent zones (De Domenico et al, 1988;Azzaro et al, 1995;Magazzù et al, 1995;Decembrini et al, 1998;Kinder and Bryden, 1990). During the summer season, the surface water is enriched with nutrients and is advected towards the surrounding areas, where a decrease of nutrients and increase of chlorophyll−a occurs, namely in the north (Gulf of Gioia Tauro; Innamorati et al, 1996) and along the southeastern Sicilian coast (Böhm et al,1987;Decembrini et al, 2004;Raffa and Hopkins, 2004). In other marine ecosystems, low phytoplankton growth is due to nutrient depletion of the euphotic layer.…”

Section: Discussionmentioning

confidence: 99%

Seasonal variability of phytoplankton fluorescence in relation to the Straits of Messina (Sicily) tidal upwelling

et al. 2007

Self Cite

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Abstract. In the Straits of Messina, large gradients of tidal displacements, as well as the topographic constrictions, determine the upwelling of deeper waters in the surface layer. This work describes the seasonal variability in the surface distribution of phytoplankton biomass depending on the upwelling phenomena. Temperature, salinity, nitrates and phytoplankton fluorescence were measured in 1994 and 1995 by continuous underway surface real-time measurements onboard dedicated research boats. Each survey was performed following the dynamic phases of flooding and ebbing tides. Tidal currents are essentially southward during high tide and northward during low tide.During the low water slack tide, large spatial gradients of physical-chemical and biological parameters were found, while at the high water slack tide, a diffused phytoplankton fluorescence was observed only in autumn due to a seasonal thermocline. Salinity, nitrate and chlorophyll-a fluorescence data revealed a significant positive intercorrelation, whereas they were inversely correlated with temperature. Generally, the upwelling distribution was limited to narrow zones during winter, while in summer it was found in the middle of the Straits and in the southern zones. During spring in the southern zone of the Straits, the maximum chlorophyll-a fluorescence was detected (May 1995, 0.32 µg-Chla l −1 ); in summer, when back and forth tidal movements between the Tyrrhenian and the Ionian seas intensify, decreased values were observed throughout the study area.The data set obtained through continuous and repeatable samplings has allowed the study of different time-space scales in the Straits of Messina, a very strong and dynamic environment.The Straits system could be compared to an "intermittent pump" which, during the different seasons, initially enriches itself and subsequently provides nutrients to the surrounding basins.

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Circulation and water mass structure over a narrow shelf, Augusta Gulf (sicily)

Cited by 14 publications

References 11 publications

New coring study in Augusta Bay expands understanding of offshore tsunami deposits (Eastern Sicily, Italy)

New coring study in Augusta Bay expands understanding of offshore tsunami deposits (Eastern Sicily, Italy)

Seasonal variability of phytoplankton fluorescence in relation to the Straits of Messina (Sicily) tidal upwelling

Seasonal variability of phytoplankton fluorescence in relation to the Straits of Messina (Sicily) tidal upwelling

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