Planktonic ciliates in the oligotrophic Mediterranean Sea: longitudinal trends of standing stocks, distributions and analysis of food vacuole contents

Pitta, Paraskevi; Giannakourou, Antonia; Christaki, Urania

doi:10.3354/ame024297

Cited by 116 publications

(96 citation statements)

References 70 publications

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“…These high values contrast with those for the Aegean Sea, where ciliate abundance was always lower than 5×10 2 cells l −1 (Pitta and Giannakourou, 2000). Pitta et al (2001) reported a 2-fold decrease in ciliates concentration from west to east. However, a decline in concentrations along the west-to-east oligotrophy gradient has not been found to be always true for the ciliate standing stock (e.g., Dolan et al, 1999).…”

Section: Ciliatescontrasting

confidence: 41%

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Plankton in the open Mediterranean Sea: a review

et al. 2010

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Abstract. We present an overview of the plankton studies conducted during the last 25 years in the epipelagic offshore waters of the Mediterranean Sea. This quasi-enclosed sea is characterized by a rich and complex physical dynamics with distinctive traits, especially in regard to the thermohaline circulation. Recent investigations have basically confirmed the long-recognised oligotrophic nature of this sea, which increases along both the west-east and the north-south directions. Nutrient availability is low, especially for phosphorous (N:P up to 60), though this limitation may be buffered by inputs from highly populated coasts and from the atmosphere. Phytoplankton biomass, as chl a, generally displays low values (less than 0.2 µg chl a l −1 ) over large areas, with a modest late winter increase. A large bloom (up to 3 µg l −1 ) is observed throughout the late winter and spring exclusively in the NW area. Relatively high biomass values are recorded in fronts and cyclonic gyres. A deep chlorophyll maximum is a permanent feature for the whole basin, except during the late winter mixing. It is found at increasingly greater depths ranging from 30 m in the Alboran Sea to 120 m in the easternmost Levantine basin. Primary production reveals a west-east decreasing trend and ranges between 59 and 150 g C m −2 y −1 (in situ measurements). Overall, the basin is largely dominated by small autotrophs, microheterotrophs and egg-carrying copepod species. The microorganisms (phytoplankton, viruses, bacteria, flagellates and ciliates) and zooplankton components reveal a considerable diversity and

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Section: Ciliatescontrasting

confidence: 41%

“…In the Ligurian Sea, Peréz et al (1997) estimated that ciliates could graze from 8 to 40% of primary production. The importance of ciliates as primary production consumers seems to be higher in the EMS Pitta et al, 2001). …”

Section: Ciliatesmentioning

confidence: 99%

Plankton in the open Mediterranean Sea: a review

et al. 2010

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“…The lower ciliate population density at Abu Galoum (site 3), for example, was still two times higher than that found at the northern part of the Gulf of Aqaba (3534 cells L -1 ) in the earlier study by Claessens et al (2008). Moreover, the densities of ciliate populations in the Gulf of Aqaba were up to eight-fold higher than abundances in other comparable studies in nutrient poor systems (Revelante and Gilmartin 1990;James and Hall, 1995;Pitta et al, 2001) and were comparable with maximum values found in coastal waters or in more productive open ocean systems (Stoecker et al, 1989;Leakey et al, 1996).…”

Section: Discussionmentioning

confidence: 45%

“…A strong correlation between ciliates and chlorophyll a predicts that low phytoplankton biomass in nutrient-poor waters should be accompanied by low ciliate biomass (Pitta et al, 2001). However, despite the oligotrophic status of the Gulf of Aqaba, which was supported by very low densities of autotrophic nanoflagellates, ciliate density was unexpectedly high.…”

Section: Discussionmentioning

confidence: 91%

“…For this study, three convenient sampling sites were selected in the Gulf of Aqaba, the first in Ras Mohammed protectorate, the second in Nabq protectorate and the third in Abu Galoum protectorate. The strong correlation between ciliates and chlorophyll a predicts that low phytoplankton biomass in nutrient-poor waters should be accompanied by low ciliate abundance (Pitta et al, 2001). Since levels of chlorophyll a in the Gulf of Aqaba are low it was expected that ciliate abundance in the Gulf of Aqaba would also to be rather low.…”

Section: Introductionmentioning

confidence: 99%

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El‐Serehy¹,

Al-Rasheid²,

Shafik³

2012

Turk. J. Fish. Aquat. Sci.

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Population densities of filter feeding ciliates in the water of the three marine protectorates of Ras Mohammed, Nabq and Abu Galoum in the Gulf of Aqaba at the northern Red Sea, were estimated during the period from November 2006 to November 2007. Also, autotrophic nanoflagellates, heterotrophic nanoflagellates and heterotrophic bacteria were characterised in order to gain some indication of the food resources for ciliates. The abundance of ciliates in the waters of the three protectorates were found to vary according to an annual cycle, with the highest ciliate numbers of 2.5x10 4 cells L -1 occurring in the spring and the lowest numbers of 0.2x10 4 cells L -1 occurring in the summer. Abundances were at times eightfold higher than those found in comparable studies of nutrient-poor pelagic systems and approached those observed in coastal waters and in more productive open ocean systems. Nanoflagellates that could provide a food supply for the filter feeding ciliates were especially numerous during spring, and it is confirmed that the production of bacteria is an important component at the base of this food chain in the waters of the three marine protectorates. The study explored these food chain relationships by calculating the potential rate of capture of prey and the clearance rate of heterotrophic nanoflagellates and filter feeding ciliates. The study also compared the filtration rates of heterotrophic flagellates and of filter feeding ciliates.

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Structure and interactions within the pelagic microbial food web (from viruses to microplankton) across environmental gradients in the Mediterranean Sea

Poi

Blason

Corinaldesi

et al. 2013

Global Biogeochemical Cycles

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We have investigated here the structure of the pelagic microbial food web and quantified the carbon fluxes from viruses to microplankton along trophic gradients in the Mediterranean Sea. To explore the complex trophic pathways of the pelagic food web, we conducted independent and replicated experiments to measure (i) predation on prokaryotes by microzooplankton, (ii) predation on prokaryotes by heterotrophic nanoflagellates, (iii) virus‐induced prokaryotic mortality, and (iv) microzooplankton grazing on nanoplankton and microphytoplankton. Our study covered more than 5000 km, from the Atlantic Ocean to the Levantine basin, and from conditions of high primary production and nutrient availability to ultraoligotrophic and phosphate‐limited waters. Microphytoplankton abundance and biomass were typically scarce across the entire Mediterranean basin, with almost negligible levels in the eastern part. Also, nanoplankton biomass was typically low. Conversely, prokaryotes, and particularly the heterotrophic components, were abundant and represented the only significant food source for both nanoplankton and microplankton grazers. Viral infections were not the primary agents of prokaryotic mortality, but in some areas, such as the Ligurian Sea, they had a key role in prokaryotic dynamics. The scenario depicted in this study in summer reveals the pivotal role of microzooplankton in the pelagic food web of the Mediterranean Sea, with a key role in the potential transfer of biomass to higher trophic levels. We also show that converse to theoretical expectations, the microbial food web was relatively complex under the mesotrophic conditions (Atlantic and western Mediterranean) and was much more simplified in the ultraoligotrophic conditions of the eastern Mediterranean.

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Planktonic ciliates in the oligotrophic Mediterranean Sea: longitudinal trends of standing stocks, distributions and analysis of food vacuole contents

Cited by 116 publications

References 70 publications

Plankton in the open Mediterranean Sea: a review

Plankton in the open Mediterranean Sea: a review

Untitled

Structure and interactions within the pelagic microbial food web (from viruses to microplankton) across environmental gradients in the Mediterranean Sea

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