Pelagic primary production in the coastal Mediterranean Sea: variability, trends, and contribution to basin-scale budgets

Abstract. We estimated pelagic primary production (PP) in the coastal (<200 m depth) Mediterranean Sea from satellite-borne data, its contribution to basin-scale carbon fixation, its variability, and long-term trends during the period 2002–2016. Annual coastal PP was estimated at 0.041 Gt C, which approximately represents 12 % of total carbon fixation in the Mediterranean Sea. About 51 % of this production occurs in the eastern basin, whereas the western and Adriatic shelves contribute with ∼25 % each of total coastal production. Strong regional variability is revealed in coastal PP, from high-production areas (>300 g C m−2) associated with major river discharges to less productive provinces (<50 g C m−2) located in the southeastern Mediterranean. PP variability in the Mediterranean Sea is dominated by interannual variations, but a notable basin-scale decline (17 %) has been observed since 2012 concurring with a period of increasing sea surface temperatures in the Mediterranean Sea and positive North Atlantic Oscillation and Mediterranean Oscillation climate indices. Long-term trends in PP reveal slight declines in most coastal areas (−0.05 to −0.1 g C m−2 per decade) except in the Adriatic where PP increases at +0.1 g C m−2 per decade. Regionalization of coastal waters based on PP seasonal patterns reveals the importance of river effluents in determining PP in coastal waters that can regionally increase up to 5-fold. Our study provides insight into the contribution of coastal waters to basin-scale carbon balances in the Mediterranean Sea while highlighting the importance of the different temporal and spatial scales of variability.

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Basin scale dissolved oxygen interannual variability of the Mediterranean Sea: Analysis of long-term observations

10.5194/egusphere-egu2020-15189 ◽

2020 ◽

Author(s):

Apostolia-Maria Mavropoulou ◽

Vassilios Vervatis ◽

Sarantis Sofianos

Keyword(s):

Dissolved Oxygen ◽

Mediterranean Sea ◽

Interannual Variability ◽

Biological Effects ◽

Marine Ecosystem ◽

Mediterranean Ecosystem ◽

Biogeochemical Processes ◽

Basin Scale ◽

The Mediterranean

The Mediterranean Sea is characterized by a combination of long-term trends and climatic shifts known in the literature as &#8220;transients&#8221;, that impact the biogeochemical processes. &#160;We focus on the dissolved oxygen (DO) concentration, as it is an essential oceanic parameter for the marine ecosystem functioning. Dissolved oxygen distribution in the ocean interior is controlled by air-sea interaction processes, ocean circulation patterns, and biological effects. Understanding the related mechanisms and the variability of the above processes requires systematic oceanographic measurements over long periods and at high spatial resolution. Taking advantage of the Mediterranean monitoring systems, we can examine the sensitive physical and biogeochemical processes in the Mediterranean ecosystem. In this study, we investigate and combine all available data of temperature, salinity and dissolved oxygen over the period 1960-2011 (taking into consideration the scarcity of the available DO observations during the last years). In order to receive a direct and accurate evaluation of the interannual changes in the Mediterranean Sea, we constructed a gridded dataset interpolated into 1/8&#959; x 1/8&#959; grid using Data-Interpolating Variational Analysis (DIVA). At the surface layer, the solubility-driven changes determine the dissolved oxygen concentration. In deeper layers, the interannual variability is more related to dynamical processes that may involve dense-water convection, biological consumption or mixing, rather than temperature trends. The observed changes in minimum/maximum oxygen zones are mostly related to abrupt shifts. The attribution of the observed variability involves complex physical and biogeochemical processes as well as anthropogenic activities and requires further analysis using modeling techniques and available operational tools.

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Seasonal and inter-annual variability of plankton chlorophyll and primary production in the Mediterranean Sea: a modelling approach

Biogeosciences Discussions ◽

10.5194/bgd-8-5379-2011 ◽

2011 ◽

Vol 8 (3) ◽

pp. 5379-5422 ◽

Cited By ~ 7

Author(s):

P. Lazzari ◽

C. Solidoro ◽

V. Ibello ◽

S. Salon ◽

A. Teruzzi ◽

...

Keyword(s):

Primary Production ◽

Mediterranean Sea ◽

Seasonal Variability ◽

Net Primary Production ◽

Eastern Mediterranean ◽

Light Extinction ◽

Spatial And Temporal Variability ◽

Nutrient Loads ◽

Basin Scale ◽

The Mediterranean

Abstract. This study presents a model of chlorophyll and primary production in the pelagic Mediterranean Sea. A 3-D-ecosystem model (OPATM-BFM) was adopted to explore specific system characteristics and quantify key biogeochemical variables covering a 6-yr period, from 1999 to 2004. We show that, on a basin scale, the Mediterranean Sea is characterised by a high degree of spatial and temporal variability in terms of primary production and chlorophyll concentrations. On a spatial scale, important horizontal and vertical gradients have been observed. In particular, notable differences between surface net primary production variability and the corresponding vertically integrated production rates have been identified, suggesting that care must be taken when inferring productivity in such systems from satellite observations alone. The present study indicates that seasonal variability dominates inter-annual differences. According to the simulations over a 6-yr period, the developed model correctly simulated the climatological features of deep chlorophyll maxima and chlorophyll west-east gradients, as well as the seasonal variability in the primary offshore regions that were studied. The integrated net primary production highlights north-south gradients that differ from surface net primary production gradients and illustrates the importance of adopting a spatial and temporal description to calculate basin-wide budgets and their variabilities. According to the model, the western Mediterranean, in particular the Alboran Sea, can be considered mesotrophic, whereas the eastern Mediterranean is oligotrophic. Finally, specific simulations that were designed to explore the role of ecosystem boundary conditions were performed. The subsequent results show that the effects of atmospheric and terrestrial nutrient loads on the total integrated net primary production account for less than 5 % of the annual budget, whereas an increase of 30 % in the light extinction factor impacts primary production by approximately 10 %.

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Seasonal and inter-annual variability of plankton chlorophyll and primary production in the Mediterranean Sea: a modelling approach

Biogeosciences ◽

10.5194/bg-9-217-2012 ◽

2012 ◽

Vol 9 (1) ◽

pp. 217-233 ◽

Cited By ~ 97

Author(s):

P. Lazzari ◽

C. Solidoro ◽

V. Ibello ◽

S. Salon ◽

A. Teruzzi ◽

...

Keyword(s):

Primary Production ◽

Mediterranean Sea ◽

Net Primary Production ◽

Eastern Mediterranean ◽

Light Extinction ◽

Biogeochemical Model ◽

Spatial And Temporal Variability ◽

Nutrient Loads ◽

Basin Scale ◽

The Mediterranean

Abstract. This study presents a model of chlorophyll and primary production in the pelagic Mediterranean Sea. A 3-D-biogeochemical model (OPATM-BFM) was adopted to explore specific system characteristics and quantify dynamics of key biogeochemical variables over a 6 yr period, from 1999 to 2004. We show that, on a basin scale, the Mediterranean Sea is characterised by a high degree of spatial and temporal variability in terms of primary production and chlorophyll concentrations. On a spatial scale, important horizontal and vertical gradients have been observed. According to the simulations over a 6 yr period, the developed model correctly simulated the climatological features of deep chlorophyll maxima and chlorophyll west-east gradients, as well as the seasonal variability in the main offshore regions that were studied. The integrated net primary production highlights north-south gradients that differ from surface net primary production gradients and illustrates the importance of resolving spatial and temporal variations to calculate basin-wide budgets and their variability. According to the model, the western Mediterranean, in particular the Alboran Sea, can be considered mesotrophic, whereas the eastern Mediterranean is oligotrophic. During summer stratified period, notable differences between surface net primary production variability and the corresponding vertically integrated production rates have been identified, suggesting that care must be taken when inferring productivity in such systems from satellite observations alone. Finally, specific simulations that were designed to explore the role of external fluxes and light penetration were performed. The subsequent results show that the effects of atmospheric and terrestrial nutrient loads on the total integrated net primary production account for less than 5 % of the its annual value, whereas an increase of 30 % in the light extinction factor impacts primary production by approximately 10 %.

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Long-term monitoring programme of the hydrological variability in the Mediterranean Sea: a first overview of the HYDROCHANGES network

Ocean Science ◽

10.5194/os-9-301-2013 ◽

2013 ◽

Vol 9 (2) ◽

pp. 301-324 ◽

Cited By ~ 37

Author(s):

K. Schroeder ◽

C. Millot ◽

L. Bengara ◽

S. Ben Ismail ◽

M. Bensi ◽

...

Keyword(s):

Time Series ◽

Mediterranean Sea ◽

Sampling Interval ◽

Global Changes ◽

Hydrological Variability ◽

Long Term Monitoring ◽

The Mediterranean ◽

Set Up ◽

Term Monitoring

Abstract. The long-term monitoring of basic hydrological parameters (temperature and salinity), collected as time series with adequate temporal resolution (i.e. with a sampling interval allowing the resolution of all important timescales) in key places of the Mediterranean Sea (straits and channels, zones of dense water formation, deep parts of the basins), constitute a priority in the context of global changes. This led CIESM (The Mediterranean Science Commission) to support, since 2002, the HYDROCHANGES programme (http//www.ciesm.org/marine/programs/hydrochanges.htm), a network of autonomous conductivity, temperature, and depth (CTD) sensors, deployed on mainly short and easily manageable subsurface moorings, within the core of a certain water mass. The HYDROCHANGES strategy is twofold and develops on different scales. To get information about long-term changes of hydrological characteristics, long time series are needed. But before these series are long enough they allow the detection of links between them at shorter timescales that may provide extremely valuable information about the functioning of the Mediterranean Sea. The aim of this paper is to present the history of the programme and the current set-up of the network (monitored sites, involved groups) as well as to provide for the first time an overview of all the time series collected under the HYDROCHANGES umbrella, discussing the results obtained thanks to the programme.

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Mediterranean Sea climatic indices: monitoring long term variability and climate changes

10.5194/essd-2018-51 ◽

2018 ◽

Author(s):

Athanasia Iona ◽

Athanasios Theodorou ◽

Sarantis Sofianos ◽

Sylvain Watelet ◽

Charles Troupin ◽

...

Keyword(s):

Climate Change ◽

Time Series ◽

Mediterranean Sea ◽

Climate Changes ◽

Salt Content ◽

Climatic Indices ◽

In Situ Observations ◽

The Mediterranean

Abstract. We present a new product composed of a set of thermohaline climatic indices from 1950 to 2015 for the Mediterranean Sea such as decadal temperature and salinity anomalies, their mean values over selected depths, decadal ocean heat and salt content anomalies at selected depth layers as well as their long times series. It is produced from a new high-resolution climatology of temperature and salinity on a 1/8° regular grid based on historical high quality in situ observations. Ocean heat and salt content differences between 1980–2015 and 1950–1979 are compared for evaluation of the climate shift in the Mediterranean Sea. The spatial patterns of heat and salt content shifts demonstrate in greater detail than ever before that the climate changes differently in the several regions of the basin. Long time series of heat and salt content for the period 1950 to 2015 are also provided which indicate that in the Mediterranean Sea there is a net mean volume warming and salting since 1950 with acceleration during the last two decades. The time series also show that the ocean heat content seems to fluctuate on a cycle of about 40 years and seems to follow the Atlantic Multidecadal Oscillation climate cycle indicating that the natural large scale atmospheric variability could be superimposed on to the warming trend. This product is an observations-based estimation of the Mediterranean climatic indices. It relies solely on spatially interpolated data produced from in-situ observations averaged over decades in order to smooth the decadal variability and reveal the long term trends with more accuracy. It can provide a valuable contribution to the modellers' community, next to the satellite-based products and serve as a baseline for the evaluation of climate-change model simulations contributing thus to a better understanding of the complex response of the Mediterranean Sea to the ongoing global climate change. The product is available here: https://doi.org/10.5281/zenodo.1210100.

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Review of “Long-term trends in pH in Japanese coastal waters”

10.5194/bg-2019-150-rc2 ◽

2019 ◽

Author(s):

Anonymous

Keyword(s):

Coastal Waters ◽

Long Term Trends

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Sponge community variation along the Apulian coasts (Otranto Strait) over a pluri-decennial time span. Does water warming drive a sponge diversity increasing in the Mediterranean Sea?

Journal of the Marine Biological Association of the United Kingdom ◽

10.1017/s0025315419000651 ◽

2019 ◽

Vol 99 (7) ◽

pp. 1519-1534 ◽

Cited By ~ 1

Author(s):

Gabriele Costa ◽

Giorgio Bavestrello ◽

Valerio Micaroni ◽

Maurizio Pansini ◽

Francesca Strano ◽

...

Keyword(s):

Mediterranean Sea ◽

Benthic Communities ◽

Time Span ◽

Biodiversity Monitoring ◽

Sponge Diversity ◽

Community Variation ◽

The Mediterranean ◽

Changes Over Time ◽

Mass Mortalities

AbstractClimate change and heavy anthropic pressures are giving rise to important modifications in the rocky benthic communities of the Mediterranean Sea. In particular, sponge assemblages have been deeply affected due to the susceptibility of some species to dramatic phenomena such as mass mortalities or widespread variations in the abundance of other species. For this reason, long-term biodiversity monitoring of the sponge assemblages is important for understanding the direction of changes over time. We studied the sponge fauna living off Tricase Porto (Otranto Strait) and compared its composition with the results of a study conducted in the same area 50 years ago. The comparison indicated that the sponge diversity of this area has strongly increased in the last 50 years and a large number of the sponges recorded in the old survey are still present in the recent community. This evidence matches with other results obtained from different localities of the Mediterranean Sea indicating an increase of sponge diversity, possibly due to the present water warming. The description of two new Demosponge species, Diplastrella boeroi sp. nov. and Spirastrella angulata sp. nov., is also provided.

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A Synergetic Approach for the Space-Based Sea Surface Currents Retrieval in the Mediterranean Sea

Remote Sensing ◽

10.3390/rs11111285 ◽

2019 ◽

Vol 11 (11) ◽

pp. 1285 ◽

Cited By ~ 4

Author(s):

Daniele Ciani ◽

Marie-Hélène Rio ◽

Milena Menna ◽

Rosalia Santoleri

Keyword(s):

Numerical Model ◽

Mediterranean Sea ◽

Mediterranean Area ◽

Hf Radar ◽

Sea Surface ◽

Reconstruction Method ◽

Surface Currents ◽

Basin Scale ◽

The Mediterranean ◽

Sicily Channel

We present a method for the remote retrieval of the sea surface currents in the Mediterranean Sea. Combining the altimeter-derived currents with sea-surface temperature information, we created daily, gap-free high resolution maps of sea surface currents for the period 2012–2016. The quality of the new multi-sensor currents has been assessed through comparisons to other surface-currents estimates, as the ones obtained from drifting buoys trajectories (at the basin scale), or HF-Radar platforms and ocean numerical model outputs in the Malta–Sicily Channel. The study yielded that our synergetic approach can improve the present-day derivation of the surface currents in the Mediterranean area up to 30% locally, with better performances for the the meridional component of the motion and in the western section of the basin. The proposed reconstruction method also showed satisfying performances in the retrieval of the ageostrophic circulation in the Sicily Channel. In this area, assuming the High Frequency Radar-derived currents as reference, the merged multi-sensor currents exhibited improvements with respect to the altimeter estimates and numerical model outputs, mainly due to their enhanced spatial and temporal resolution.

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The changing face of the Mediterranean – Land cover, demography and environmental change: Introduction and overview

The Holocene ◽

10.1177/0959683619826688 ◽

2019 ◽

Vol 29 (5) ◽

pp. 703-707 ◽

Cited By ~ 11

Author(s):

Andrew Bevan ◽

Alessio Palmisano ◽

Jessie Woodbridge ◽

Ralph Fyfe ◽

C Neil Roberts ◽

...

Keyword(s):

Land Cover ◽

Environmental Change ◽

Special Issue ◽

Demographic Trends ◽

Human Environment ◽

Research Initiative ◽

Long Term Trends ◽

The Mediterranean

This paper introduces a special issue on The Changing Face of the Mediterranean: Land Cover, Demography, and Environmental Change, which brings together up-to-date regional or thematic perspectives on major long-term trends in Mediterranean human–environment relations. Particularly, important insights are provided by palynology to reconstruct past vegetation and land cover, and archaeology to establish long-term demographic trends, but with further significant input from palaeoclimatology, palaeofire research and geomorphology. Here, we introduce the rationale behind this pan-Mediterranean research initiative, outline its major sources of evidence and method, and describe how individual submissions work to complement one another.

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A high-resolution free-surface model of the Mediterranean Sea

Ocean Science ◽

10.5194/os-4-1-2008 ◽

2008 ◽

Vol 4 (1) ◽

pp. 1-14 ◽

Cited By ~ 144

Author(s):

M. Tonani ◽

N. Pinardi ◽

S. Dobricic ◽

I. Pujol ◽

C. Fratianni

Keyword(s):

Free Surface ◽

Mediterranean Sea ◽

General Circulation ◽

Forecast Model ◽

Surface Model ◽

Argo Data ◽

Basic Model ◽

Basin Scale ◽

Before And After ◽

The Mediterranean

Abstract. This study describes a new model implementation for the Mediterranean Sea with what is currently the highest vertical resolution over the Mediterranean basin. The resolution is of 1/16°×1/16° in the horizontal and has 72 unevenly spaced vertical levels. This model has been developed in the frame of the EU-MFSTEP project and is the operational forecast model currently used at the basin scale. The model considers an implicit free surface and this characteristic enhances the model's capability to simulate the sea surface height variability and the net transport at the Strait of Gibraltar. In this study we show the calibration/validation experiments performed before and after the model was used for forecasting. The first experiment consists of a six-year simulation forced by a perpetual year forcing, and the other experiment is a simulation from January 1997 to December 2004, forcing the model with 6-h atmospheric forcing fields from ECMWF. The model Sea Level Anomaly has been compared for the first time with satellite SLA and with ARGO data to provide evidence of the quality of the simulation. The results show that this model is capable of reproducing most of the variability of the general circulation in the Mediterranean Sea. However, some basic model inadequacies stand out and should be corrected in the near future.

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