Nutrient, particulate matter and phytoplankton variability in the photic layer of the Otranto strait

Socal, Giorgio; Boldrin, A.; Bianchi, Franco; Civitarese, Giuseppe; Lazzari, Amelia De; Rabitti, Sandro; Totti, Cecilia; Turchetto, M.

doi:10.1016/s0924-7963(98)00075-x

Cited by 70 publications

(51 citation statements)

References 32 publications

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“…General food web structure POM collected 3 m above the bottom on SML coral mounds exhibited C:N values (~7 to 9) similar to data reported for surface POM in the southern Adriatic and northern Ionian Seas (Socal et al 1999, Boldrin et al 2002) and match C:N ratios of living phytoplankton. δ 13 C values of POM (~-22 ‰) also reflect the typical signature of marine phytoplanktonic production of this Mediterranean area (Martinotti et al 1997, Sarà 2006.…”

Section: Discussionsupporting

confidence: 74%

Trophic relationships in a deep Mediterranean cold-water coral bank (Santa Maria di Leuca, Ionian Sea)

Carlier¹,

Guilloux²,

Olu³

et al. 2009

Mar. Ecol. Prog. Ser.

130

100

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Cold-water corals (CWC) are frequently reported from deep sites with locally accelerated currents that enhance seabed food particle supply. Moreover, zooplankton likely account for ecologically important prey items, but their contribution to CWC diet remains unquantified. We investigated the benthic food web structure of the recently discovered Santa Maria di Leuca (SML) CWC province (300 to 1100 m depth) located in the oligotrophic northern Ionian Sea. We analyzed stable isotopes (δ 13 C and δ 15 N) of the main consumers (including ubiquitous CWC species) exhibiting different feeding strategies, zooplankton, suspended particulate organic matter (POM) and sedimented organic matter (SOM). Zooplankton and POM were collected 3 m above the coral colonies in order to assess their relative contributions to CWC diet. The δ 15 N of the scleractinians Desmophyllum dianthus, Madrepora oculata and Lophelia pertusa (8 to 9 ‰) and the gorgonian Paramuricea cf. macrospina (9 to 10 ‰) were consistent with a diet mainly composed of zooplankton (6 to 7 ‰). The antipatharian Leiopathes glaberrima was more 15 N-depleted (7 to 8 ‰) than other cnidarians, suggesting a lower contribution of zooplankton to its diet. Our δ 13 C data clearly indicate that the benthic food web of SML is exclusively fuelled by carbon of phytoplanktonic origin. Nevertheless, consumers feeding at the water-sediment interface were more 13 C-enriched than consumers feeding above the bottom (i.e. living corals and their epifauna). This pattern suggests that carbon is assimilated via 2 trophic pathways: relatively fresh phytoplanktonic production for 13 C-depleted consumers and more decayed organic matter for 13 C-enriched consumers. When the δ 13 C values of consumers were corrected for the influence of lipids (which are significantly 13 C-depleted relative to other tissue components), our conclusions remained unchanged, except in the case of L. glaberrima which could assimilate a mixture of zooplankton and resuspended decayed organic matter.

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Section: Discussionsupporting

confidence: 74%

Trophic relationships in a deep Mediterranean cold-water coral bank (Santa Maria di Leuca, Ionian Sea)

Carlier¹,

Guilloux²,

Olu³

et al. 2009

Mar. Ecol. Prog. Ser.

130

100

View full text Add to dashboard Cite

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“…While most of the nitrogen is advected out of the northern basin, phosphorous is efficiently removed from the water column, brought to organic form and possibly buried in the bottom sediments on the Adriatic shelf. However, even though Socal et al (1999) confirmed the thesis of P-limited Adriatic, the significant presence of diatoms was explained by new production sustained by regenerative processes and DOP and DON as important sources of nutrients. Degobbis et al (2005) analysed changes in nutrient ratios in relation to mucilage events in the northern Adriatic.…”

Section: Discussionmentioning

confidence: 74%

“…Gilmartin et al, 1990). Socal et al (1999) found that the Adriatic Surface Water (ASW) of the photic layer of the Otranto Strait was charactherized by an excess of nitrogen (N:P=50). While most of the nitrogen is advected out of the northern basin, phosphorous is efficiently removed from the water column, brought to organic form and possibly buried in the bottom sediments on the Adriatic shelf.…”

Section: Discussionmentioning

confidence: 99%

NW Adriatic Sea biogeochemical variability in the last 20 years (1986–2005)

et al. 2007

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Abstract. This paper presents a long-term time series (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) of hydrological and biogeochemical data, both published and unpublished. Data were collected in the northwestern area of the Adriatic Sea, at two stations that are considered hydrodynamically and trophically different. The time series have been statistically and graphically analysed on a monthly scale in order to study the annual climatologies, links between the concentrations of chlorophyll-a and the variability in the environment, trophic differences between the two areas and chlorophyll-a trends over time. Basically, the two areas have similar hydrological features, yet they present significant differences in the amount of nutrient inputs: these are in fact higher at the coastal site, which is characterized by a prevalence of surface blooms, while they are lower at the offshore station, which is mainly affected by blooms at intermediate depths. Nonetheless, throughout the whole water column, chlorophyll-a concentrations are only slightly different. Both areas are affected by riverine discharge, though chlorophyll-a concentrations are also driven strongly by the seasonal cycle at the station closer to the coast. Results show that the two stations are not trophically different, although some controlling factors, such as zooplankton grazing in one case and light attenuation in the other, may further regulate the growth of phytoplankton. In both cases no significant trends are detected in either the average chlorophyll-a values or in dispersion of the data, in contrast with significant trends in temperature and salinity.

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“…One-half of oceanic primary production on average is channelled via bacteria into the microbial loop (Azam et al 1983;Cole et al 1988). In oligotrophic systems, heterotrophic bacterial biomass is generally equal to that of the phytoplanktonic or often greater (Robarts et al, 1996;Socal et al, 1999). Microbes consume an estimated 75% of the sinking particulate organic carbon flux in the upper 500 m (Karl et al, 1988;Cho and Azam, 1990).…”

Section: Introductionmentioning

confidence: 99%

Seasonal to hour variation scales in abundance and production of total and particle-attached bacteria in the open NW Mediterranean Sea (0–1000 m)

et al. 2008

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Abstract. We present the vertical and temporal dynamics of total vs. particle-attached bacterial abundance and activity over a 5 week period under summer to autumn transition in NW Mediterranean Sea. At a weekly time scale, total bacterial biomass and production in the euphotic layers was significantly correlated with phytoplanktonic biomass. At an hourly time scale, total bacterial biomass responded very rapidly to chlorophyll a fluctuations, suggesting a tight coupling between phytoplankton and bacteria for resource partitioning during the summer-autumn transition. In contrast, no influence of diel changes on bacterial parameters was detected. Episodic events such as coastal water intrusions had a significant positive effect on total bacterial abundance and production, whereas we could not detect any influence of short wind events whatever the magnitude. Finally, we show that particle-attached bacteria can represent a large proportion (up to 49%) of the total bacterial activity in the euphotic layer but display rapid and sporadic changes at hourly time scales. In the mesopelagic layers, bacterial abundance and production linearly decreased with depth, except some production peaks at 400-750 m. This study underlines the value of large datasets covering different temporal scales to clarify the biogeochemical role of bacteria in the cycling of organic matter in open seawater.

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Nutrient, particulate matter and phytoplankton variability in the photic layer of the Otranto strait

Cited by 70 publications

References 32 publications

Trophic relationships in a deep Mediterranean cold-water coral bank (Santa Maria di Leuca, Ionian Sea)

Trophic relationships in a deep Mediterranean cold-water coral bank (Santa Maria di Leuca, Ionian Sea)

NW Adriatic Sea biogeochemical variability in the last 20 years (1986–2005)

Seasonal to hour variation scales in abundance and production of total and particle-attached bacteria in the open NW Mediterranean Sea (0–1000 m)

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