Summary and overview of the CYCLOPS P addition Lagrangian experiment in the Eastern Mediterranean

Krom, Michael D.; Thingstad, T. Frede; Brenner, S.; Carbo, P.; Δρακόπουλος, Πάνος; Fileman, T.W.; Flaten, Gro Anita Fonnes; Groom, Steve; Herut, Barak; Kitidis, Vassilis; Kress, Nurit; Law, Cliff S.; Liddicoat, M.I.; Mantoura, R.F.C.; Pasternak, A. F.; Pitta, Paraskevi; Polychronaki, Thalia; Psarra, Stella; Rassoulzadegan, Fereidoun; Skjoldal, Evy Foss; Spyres, G.; Tanaka, Tsuneo; Τσελεπίδης, Α.; Wassmann, Paul; Riser, Christian Wexels; Woodward, E Malcolm S; Zodiatis, George; Zohary, Tamar

doi:10.1016/j.dsr2.2005.08.018

Cited by 71 publications

(37 citation statements)

References 61 publications

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“…After the winter-spring bloom period and during the summer (warm) stratification period, inorganic nutrient concentrations are extremely low in the surface layers. A Lagrangian experiment in the Levantine Sea suggested bacterioplankton limitation by phosphorus (P) and phytoplankton co-limitation by nitrogen (N) & P in the summer (Krom et al, 2005b;Pitta et al, 2005;Thingstad et al, 2005;Zohary et al, 2005). A mesocosm experiment, conducted in the Cretan Sea during late summer, using a comparable, in terms of nutrient content, but different water mass, supported these findings .…”

Section: Introductionsupporting

confidence: 61%

“…The response of bacteria to P-addition in the Eastern Mediterranean has been seen during a Lagrangian experiment (Krom et al, 2005b;Pitta et al, 2005;Thingstad et al, 2005) and verified during a mesocosm experiment . On the other hand, the increase in the autotrophic production and biomass may be attributed to the simultaneous addition of N and P through the added dust since phytoplankton has been found to be N and P-co-limited in the area Pitta et al, 2016).…”

Section: Figure 9 | (A)mentioning

confidence: 99%

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Saharan Dust Deposition Effects on the Microbial Food Web in the Eastern Mediterranean: A Study Based on a Mesocosm Experiment

et al. 2017

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The effect of episodicity of Saharan dust deposition on the pelagic microbial food web was studied in the oligotrophic Eastern Mediterranean by means of a mesocosm experiment in May 2014. Two different treatments in triplicates (addition of natural Saharan dust in a single-strong pulse or in three smaller consecutive doses of the same total quantity), and three unamended controls were employed; chemical and biological parameters were measured during a 10-day experiment. Temporal changes in primary (PP) and bacterial (BP) production, chlorophyll a (Chl a) concentration and heterotrophic bacteria, Synechococcus and mesozooplankton abundance were studied. The results suggested that the auto-and hetero-trophic components of the food web (at least the prokaryotes) were enhanced by the dust addition (and by the nitrogen and phosphorus added through dust). Furthermore, a 1-day delay was observed for PP, BP, and Chl a increases when dust was added in three daily doses; however, the maximal values attained were similar in the two treatments. Although, the effect was evident in the first osmotrophic level (phytoplankton and bacteria), it was lost further up the food web, masked under the impact of grazing exerted by predators such as heterotrophic flagellates, ciliates and dinoflagellates. This was partly proved by two dilution experiments. This study demonstrates the important role of atmospheric deposition and protist grazing when evaluating the effect on oligotrophic systems characterized by increased numbers of trophic levels.

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Section: Introductionsupporting

confidence: 61%

Section: Figure 9 | (A)mentioning

confidence: 99%

Saharan Dust Deposition Effects on the Microbial Food Web in the Eastern Mediterranean: A Study Based on a Mesocosm Experiment

et al. 2017

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“…Thus, the response of the Z treatment (N limited) after 48 h as somewhat lower than ZN (P limited) for both variables and was significantly lower than the response of the ZNA treatment where the added limiting nutrient P concentration was 40 times higher than Z and ZN (Figures 2, 3). This confirms that the dust provided a bioavailable (leachable) source of N and P as found in other studies (Herut et al, , 2002Migon et al, 2001;Ridame and Guieu, 2002) and relieved the phytoplankton community of N and P co-limitation (Kress et al, 2005;Krom et al, 2005;Pitta et al, 2005;Tanaka et al, 2011).…”

Section: Discussionsupporting

confidence: 76%

Response of the Eastern Mediterranean Microbial Ecosystem to Dust and Dust Affected by Acid Processing in the Atmosphere

et al. 2016

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Acid processes in the atmosphere, particularly those caused by anthropogenic acid gases, increase the amount of bioavailable P in dust and hence are predicted to increase microbial biomass and primary productivity when supplied to oceanic surface waters. This is likely to be particularly important in the Eastern Mediterranean Sea (EMS), which is P limited during the winter bloom and N&P co-limited for phytoplankton in summer. However, it is not clear how the acid processes acting on Saharan dust will affect the microbial biomass and primary productivity in the EMS. Here, we carried out bioassay manipulations on EMS surface water on which Saharan dust was added as dust (Z), acid treated dust (ZA), dust plus excess N (ZN), and acid treated dust with excess N (ZNA) during springtime (May 2012) and measured bacterioplankton biomass, metabolic, and other relevant chemical and biological parameters. We show that acid treatment of Saharan dust increased the amount of bioavailable P supplied by a factor of ∼40 compared to non-acidified dust (18.4 vs. 0.45 nmoles P mg −1 dust, respectively). The increase in chlorophyll, primary, and bacterial productivity for treatments Z and ZA were controlled by the amount of N added with the dust while those for treatments ZN and ZNA (in which excessive N was added) were controlled by the amount of P added. These results confirm that the surface waters were N&P co-limited for phytoplankton during springtime. However, total chlorophyll and primary productivity in the acid treated dust additions (ZA and ZNA) were less than predicted from that calculated from the amount of the potentially limiting nutrient added. This biological inhibition was interpreted as being due to labile trace metals being added with the acidified dust. A probable cause for this biological inhibition was the addition of dissolved Al, which forms potentially toxic Al Krom et al.Acidified Dust to E. Med. Microcosm nanoparticles when added to seawater. Thus, the effect of anthropogenic acid processes in the atmosphere, while increasing the flux of bioavailable P from dust to the surface ocean, may also add toxic trace metals such as Al, which moderate the fertilizing effect of the added nutrients.

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“…Knowledge of microbial nutrient limitation in different ocean provinces derives from experiments ranging from the kilometer scale of in situ enrichments (Martin et al 1994, Boyd et al 2000, Krom et al 2005 down to the centimeter scale in bottle incubations (Kirchman 1990, Zweifel et al 1993. Irrespective of the experimental scale, detection of limitation primarily relies on observation of changes in microbial production and abundance (of phyto-or bacterioplankton, or both).…”

Section: Discussionmentioning

confidence: 99%

Seasonal changes in bacterioplankton nutrient limitation and their effects on bacterial community composition in the NW Mediterranean Sea

Pinhassi¹,

Gómez‐Consarnau²,

Alonso‐Sáez³

et al. 2006

Aquat. Microb. Ecol.

157

143

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Bacterioplankton growth is expected to depend on the availability of organic and inorganic nutrients. Still, no studies have investigated how the magnitude and type of nutrient limitation experienced by marine bacteria change on a temporal scale. We carried out a series of nutrient enrichment experiments to examine the variability in nutrient limitation of bacteria in the NW Mediterranean Sea, at monthly intervals, over an 18 mo period. Short-term enrichment bioassays (24 h incubation) showed that bacterial P limitation could occur throughout the year, but was most pronounced during spring and summer, coinciding with very low concentrations of dissolved inorganic phosphorus and chlorophyll a, and higher N:P ratios. During the non-stratified period in autumn and winter, bacteria were at times strongly C limited. Inorganic nitrogen limitation was not detected at any time. Long-term bioassays with and without enrichment, where growth was monitored until stationary phase using the seawater dilution culture approach, largely confirmed the results from the short-term bioassays. Analysis of the bacterial assemblages in these cultures, using denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene sequencing, suggested that the growth of some central components of the native bacterioplankton assemblage (i.e. specific Roseobacter and Flavobacteria phylotypes) was restricted due to the limited availability of P in spring and summer. We conclude that seasonal variability in the type and severity of nutrient limitation can substantially contribute to the regulation of bacterioplankton growth and community composition, and thereby affect the turnover of dissolved organic matter and inorganic nutrients in the sea.

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Summary and overview of the CYCLOPS P addition Lagrangian experiment in the Eastern Mediterranean

Cited by 71 publications

References 61 publications

Saharan Dust Deposition Effects on the Microbial Food Web in the Eastern Mediterranean: A Study Based on a Mesocosm Experiment

Saharan Dust Deposition Effects on the Microbial Food Web in the Eastern Mediterranean: A Study Based on a Mesocosm Experiment

Response of the Eastern Mediterranean Microbial Ecosystem to Dust and Dust Affected by Acid Processing in the Atmosphere

Seasonal changes in bacterioplankton nutrient limitation and their effects on bacterial community composition in the NW Mediterranean Sea

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