Nutrient dynamics and new production in a warm-core eddy from the Eastern Mediterranean Sea

Krom, Michael D.; Brenner, S.; Kress, Nurit; Neori, Amir; Gordon, Louis

doi:10.1016/0198-0149(92)90083-6

Cited by 145 publications

(93 citation statements)

References 22 publications

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“…7a. A well-marked seasonal cycle, consistent with previous observations of Krom et al (1992), is observed. This cycle presents a strong stratification of the water column in summer, characterized by a DCM between 100 and 125 m depth.…”

Section: Autonomous Platformssupporting

confidence: 80%

Towards a merged satellite and in situ fluorescence ocean chlorophyll product

et al. 2012

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Abstract. Understanding the ocean carbon cycle requires a precise assessment of phytoplankton biomass in the oceans. In terms of numbers of observations, satellite data represent the largest available data set. However, as they are limited to surface waters, they have to be merged with in situ observations. Amongst the in situ data, fluorescence profiles constitute the greatest data set available, because fluorometers have operated routinely on oceanographic cruises since the 1970s. Nevertheless, fluorescence is only a proxy of the total chlorophyll a concentration and a data calibration is required. Calibration issues are, however, sources of uncertainty, and they have prevented a systematic and wide range exploitation of the fluorescence data set. In particular, very few attempts to standardize the fluorescence databases have been made. Consequently, merged estimations with other data sources (e.g. satellite) are lacking.We propose a merging method to fill this gap. It consists firstly in adjusting the fluorescence profile to impose a zero chlorophyll a concentration at depth. Secondly, each point of the fluorescence profile is then multiplied by a correction coefficient, which forces the chlorophyll a integrated content measured on the fluorescence profile to be consistent with the concomitant ocean colour observation. The method is close to the approach proposed by Boss et al. (2008) to correct fluorescence data of a profiling float, although important differences do exist. To develop and test our approach, in situ data from three open ocean stations (BATS, HOT and DYFAMED) were used. Comparison of the socalled "satellite-corrected" fluorescence profiles with concomitant bottle-derived estimations of chlorophyll a concentration was performed to evaluate the final error (estimated at 31 %). Comparison with the Boss et al. (2008) method, using a subset of the DYFAMED data set, demonstrated that the methods have similar accuracy. The method was applied to two different data sets to demonstrate its utility. Using fluorescence profiles at BATS, we show that the integration of "satellite-corrected" fluorescence profiles in chlorophyll a climatologies could improve both the statistical relevance of chlorophyll a averages and the vertical structure of the chlorophyll a field. We also show that our method could be efficiently used to process, within near-real time, profiles obtained by a fluorometer deployed on autonomous platforms, in our case a bio-optical profiling float. The application of the proposed method should provide a first step towards the generation of a merged satellite/fluorescence chlorophyll a product, as the "satellite-corrected" profiles should then be consistent with satellite observations. Improved climatologies with more consistent satellite and in situ data are likely to enhance the performance of present biogeochemical models.

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Section: Autonomous Platformssupporting

confidence: 80%

Towards a merged satellite and in situ fluorescence ocean chlorophyll product

et al. 2012

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“…3b). These values are consistent with what is usually measured in the surface water of the Mediterranean Sea (Krom et al, 1992;. Under these conditions, phytoplankton growth rate ranges between 0 and 0.53 d −1 (Fig.…”

Section: Environmental Conditions Growth and Nutrient Uptakesupporting

confidence: 79%

“…Since the Mediterranean Sea is assume to be P-limited, few study have focus on the dynamic of the non-limiting elements such as inorganic nitrogen. In contrast to inorganic phosphate concentrations, a substantial amount of inorganic nitrogen can remain at the surface, especially in the eastern basin (Krom et al, 1992). The main consequence is that, in the surface layer, high N:P ratio could be expected and model results displaying more than 300 nM of inorganic N with close to zero nM of P may not be unreasonable.…”

Section: Discussionmentioning

confidence: 99%

Accumulation of DOC in Low Phosphate Low Chlorophyll (LPLC) area: is it related to higher production under high N:P ratio?

2011

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Abstract. The biogeochemistry of carbon and nutrients (N,P) in the surface layer of the ocean strongly depends on the complex interactions between primary producers (phytoplankton) and remineralizers (heterotrophic bacteria). To understand how these interactions impact the overall DOC dynamics in the surface layer of the Mediterranean Sea, we implemented, using Eco3M (Ecological Mechanistic Modular Modelling tool), a multi-element model with a mechanistic description of primary production. We studied the model steady state results under various nutrient conditions and fixed cell abundances. By doing so, we show how the bottom up control of osmotrophs growth can impact the overall DOC dynamics in the system. Based on our set of parameters, the biogeochemical characteristics displayed by the model appear realistic when compared to literature data for the Mediterranean basin. Differences in DOC dynamics between N and P limited systems in the model, lead to the conclusion that the unusually high N:P ratio of the Mediterranean Sea may favour the uncoupling between growth and carbon production leading to higher DOC accumulation compared to systems with lower N:P ratio.

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“…Phytoplankton composition and primary production measurements in the eastern Mediterranean are very sparse and generally restricted to particular regions (e.g., the Shikmona gyre) [Krom et al, 1992]. To our knowledge the only basinwide study in the eastem Mediterranean is restricted to chlorophyll and primary production derived from ocean color (CZCS) data [Antoine et al, 1995].…”

Section: Discussionmentioning

confidence: 99%

Phytoplankton pigment distribution in relation to upper thermocline circulation in the eastern Mediterranean Sea during winter

Vidussi¹,

Claustre²,

Manca³

et al. 2001

J. Geophys. Res.

481

453

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Abstract. Using a sampling grid of 67 stations, the influence of basin-wide and subbasrascale circulation features on phytoplankton community composition and primary and new productions-was investigated m the eastern Mediterranean during winter. Taxonomic pigments were used as size class markers of phototroph groups (picophytoplankton, nanophytoplankton and microphytoplankton). Primary production rates-were computed using a light photosynthesis model that makes use of the total chlorophyll a (Tchl a) concentration profile as an input variable. New production was estimated as the product of primary production by a pigment-based proxy of thef ratio (new production/total production).

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Nutrient dynamics and new production in a warm-core eddy from the Eastern Mediterranean Sea

Cited by 145 publications

References 22 publications

Towards a merged satellite and in situ fluorescence ocean chlorophyll product

Towards a merged satellite and in situ fluorescence ocean chlorophyll product

Accumulation of DOC in Low Phosphate Low Chlorophyll (LPLC) area: is it related to higher production under high N:P ratio?

Phytoplankton pigment distribution in relation to upper thermocline circulation in the eastern Mediterranean Sea during winter

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