scholarly journals Demographics of the zooxanthellate coral Oculina patagonica along the Mediterranean Iberian coast in relation to environmental parameters

2018 ◽  
Vol 634 ◽  
pp. 1580-1592 ◽  
Author(s):  
Eduard Serrano ◽  
Marta Ribes ◽  
Rafel Coma
Keyword(s):  
Environmental Parameters ◽  
Zooxanthellate Coral ◽  
The Mediterranean

scholarly journals Relationships between cytometric characteristics of high and low nucleic-acid bacterioplankton cells, bacterial production and environmental parameters along a longitudinal gradient across the Mediterranean Sea

2010 ◽  
Vol 7 (6) ◽  
pp. 8245-8279 ◽  
Author(s):  
F. Van Wambeke ◽  
P. Catala ◽  
P. Lebaron
Keyword(s):  
Nucleic Acid ◽  
Mediterranean Sea ◽  
Bacterial Production ◽  
Environmental Parameters ◽  
Early Summer ◽  
Bacterial Cells ◽  
Green Fluorescence ◽  
Flow Cytometric ◽  
Chlorophyll Distribution ◽  
The Mediterranean

Abstract. Heterotrophic bacterioplankton abundance and production were determined along vertical (down to bathypelagic layers) and latitudinal (from 4.9° E to 32.7° E) gradients across the Mediterranean Sea in early summer 2008. Abundance and flow cytometric characteristics (green fluorescence and side scatter signals) of high nucleic acid (HNA) and low nucleic acid (LNA) bacterial cells were investigated using flow cytometry. Contrarily to what is generally observed, the percentage of total bacteria represented by HNA cells (%HNA, range 30–69%) decreased with increased bacterial production (range 0.15–44 ng C l−1 h−1) although this negative relation was poorly explained (log-log regression r2=0.19). The %HNA as well as the mean side scatter of this group increased significantly with depth in the meso and bathypelagic layers. Our results demonstrated that vertical stratification with regard to chlorophyll distribution above, within or below the deep chlorophyll maximum plays an important role in influencing the distribution of cells, and in the relationships between the flow cytometric parameters and environmental variables such as chlorophyll a or bacterial production. Relationships between green fluorescence and side scatter of both HNA and LNA cells depended largely on chlorophyll distribution over the water column, suggesting that the dynamic link between HNA and LNA cells differs vertically.

PCA study of the interannual variability of GPS heights and environmental parameters

2020 ◽  
Author(s):  
Letizia Elia ◽  
Susanna Zerbini ◽  
Fabio Raicich
Keyword(s):  
Time Series ◽  
Interannual Variability ◽  
Water Storage ◽  
Environmental Parameters ◽  
Space Time ◽  
Terrestrial Water Storage ◽  
Coupled Modes ◽  
Entire Study ◽  
Terrestrial Water ◽  
The Mediterranean

<p>Time series of GPS coordinates longer than two decades are now available at many stations around the world. The objective of our study is to investigate large networks of GPS stations to identify and analyze spatially coherent signals present in the coordinate time series and, at the same locations, to identify and analyze common patterns in the series of environmental parameters and climate indexes. The study is confined to Europe and the Mediterranean area, where 107 GPS stations were selected from the Nevada Geodetic Laboratory (NGL) archive on the basis of the completeness and length of the data series. The parameters of interest for this study are the stations height (H), the atmospheric surface pressure (AP), the terrestrial water storage (TWS) and the various climate indexes, such as NAO (North Atlantic Oscillation), AO (Artic Oscillation), SCAND (Scandinavian Index) and MEI (Multivariate ENSO Index). The Empirical Orthogonal Function (EOF) is the methodology adopted to extract the main patterns of space/time variability of these parameters. We also focus on the coupled modes of space/time interannual variability between pairs of variables using the singular value decomposition (SVD) methodology. The coupled variability between all the afore mentioned parameters is investigated. It shall be pointed out that EOF and SVD are mathematical tools providing common modes on the one hand, and statistical correlations between pairs of parameters on the other. Therefore, these methodologies do not allow to directly infer the physical mechanisms responsible for the observed behaviors which should be explained through appropriate modelling. Our study has identified, over Europe and the Mediterranean, main modes of variability in the time series of GPS heights, atmospheric pressure and terrestrial water storage. For example, regarding the station heights, the EOF1 explains about 30% of the variance and the spatial pattern is coherent over the entire study area. The SVD analysis of coupled parameters, namely H-AP, TWS-AP and H-TWS, showed that most of the common variability is explained by the first 3 modes. In particular, 70% for the H-AP, 67% for the TWS-AP and 49% for the H-TWS pair. Moreover, we correlated the stations heights with the NAO, AO, SCAND and MEI indexes to investigate the possible influence of climate variability on the height behavior. To do so, the stations heights were represented using the first three EOFs to reduce the potential effect of local anomalies. More than 30 stations, over the total of 107, show significant correlations up to about 0.3 with the AO and SCAND indexes. The correlation coefficients with MEI turn out to be significant and up to 0.5 for about half of the stations.</p>

scholarly journals Spring distribution of shelled pteropods across the Mediterranean Sea

2020 ◽  
Author(s):  
Roberta Johnson ◽  
Clara Manno ◽  
Patrizia Ziveri
Keyword(s):  
Climate Change ◽  
Mediterranean Sea ◽  
Eastern Mediterranean ◽  
Hot Spot ◽  
Environmental Parameters ◽  
Saturation State ◽  
Eastern Mediterranean Sea ◽  
The Mediterranean ◽  
First Time ◽  
Natural Laboratory

Abstract. Shelled pteropods represent an excellent sentinel for indicating exposure to ocean acidification (OA). Here, for the first time, we characterise spring pteropod distribution throughout the Mediterranean Sea, a region that has been identified as a climate change hot-spot. The presence of a west–east natural biogeochemical gradient makes this region a natural laboratory to investigate how the variability in environmental parameters may affect pteropod distribution. Results show that pteropod abundance is significantly higher in the eastern Mediterranean Sea where there is a higher aragonite saturation state (Ωar), showing that distribution is positively correlated with Ωar. We also observed a resilience of pteropods to higher temperatures and low nutrient conditions, including phosphorous limitation. The higher abundance of pteropods in ultra-oligotrophic conditions (eastern Mediterranean Sea) suggests that this organism can play an important role as the prime calcifying zooplankton within specific oligotrophic regions.

scholarly journals Bio-optical characterization of subsurface chlorophyll maxima in the Mediterranean Sea from a Biogeochemical-Argo float database

2018 ◽  
Author(s):  
Marie Barbieux ◽  
Julia Uitz ◽  
Bernard Gentili ◽  
Orens Pasqueron de Fommervault ◽  
Alexandre Mignot ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Chlorophyll Concentration ◽  
Environmental Parameters ◽  
Western Basin ◽  
Different Types ◽  
The Mediterranean ◽  
Spatio Temporal ◽  
The Vertical Distribution

Abstract. As commonly observed in oligotrophic stratified waters, a Subsurface (or Deep) Chlorophyll Maximum (SCM) frequently characterizes the vertical distribution of phytoplankton chlorophyll in the Mediterranean Sea. Occurring far from the surface layer seen by ocean color satellites, SCMs are difficult to observe with adequate spatio-temporal resolution and their biogeochemical impact remains unknown. BioGeochemical-Argo (BGC-Argo) profiling floats represent appropriate tools for studying the dynamics of SCMs. Based on data collected from 36 BGC-Argo floats deployed in the Mediterranean Sea, our study aims to address two main questions: (1) What are the different types of SCMs in Mediterranean Sea? (2) Which environmental factors control their occurrence and dynamics? First, we analyzed the seasonal and regional variations of the chlorophyll concentration (Chla), particulate backscattering coefficient (bbp), a proxy of the Particulate Organic Carbon (POC), and environmental parameters (PAR and nitrates) within the SCM layer over the Mediterranean basin. The vertical profiles of Chla and bbp were then statistically classified, and the seasonal occurrence of each of the different types of SCMs quantified. Finally, a case study was performed on two contrasted regions and the environmental conditions at depth were further investigated to understand which parameter controls the SCMs. In the Eastern Basin, SCMs result, at a first order, from photoacclimation process. Conversely, SCMs in the Western Basin reflect a biomass increase at depth benefiting from both light and nitrate resources. Our results also suggest that a variety of intermediate types of SCMs are encountered between these two end-member situations.

scholarly journals Using a benthic lander to explore and monitor vulnerable ecosystems in the Mediterranean Sea

ACTA IMEKO ◽  
2018 ◽  
Vol 7 (2) ◽  
pp. 45 ◽  
Author(s):  
Gianfranco D'Onghia ◽  
Francesca Capezzuto ◽  
Roberto Carlucci ◽  
Angela Carluccio ◽  
Porzia Maiorano ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Cold Water ◽  
Environmental Parameters ◽  
Small Scale ◽  
Practical Applications ◽  
Biological Variables ◽  
The Mediterranean ◽  
Marine Environment Monitoring ◽  
And Behavior ◽  
The University

<p class="Abstract">The MEMO (Marine Environment MOnitoring system) baited lander is used to explore and monitor marine ecosystems in the Mediterranean Sea. MEMO is equipped with 2 video cameras, a multiparametric probe and a current meter, fully operative down to 1000 m in depth for 24 consecutive hours. Since 2010, the ecology team of the Department of Biology of the University of Bari (Italy) deployed the MEMO lander in some sensitive and vulnerable deep-sea habitats of the Mediterranean Sea, as part of national and international research projects. Data on environmental parameters (depth, salinity, temperature and current) and related to bentho-pelagic species, their small-scale distribution, size and behavior, have been recorded. MEMO has been also deployed in fragile and structurally complex habitats, such as coralligenous and cold-water corals, in order to monitor physico-chemical and biological variables as part of the EU Marine Strategy Framework Directive. Some practical applications of the MEMO lander are reported here, with indications of relative advantages and limitations.</p>

scholarly journals Interannual Variability of GPS Heights and Environmental Parameters over Europe and the Mediterranean Area

2021 ◽  
Vol 13 (8) ◽  
pp. 1554
Author(s):  
Letizia Elia ◽  
Susanna Zerbini ◽  
Fabio Raicich
Keyword(s):  
Time Series ◽  
Interannual Variability ◽  
Environmental Parameters ◽  
Mediterranean Area ◽  
Space Time ◽  
The Arctic ◽  
Climate Indices ◽  
Geological Processes ◽  
Second Mode ◽  
The Mediterranean

Vertical deformations of the Earth’s surface result from a host of geophysical and geological processes. Identification and assessment of the induced signals is key to addressing outstanding scientific questions, such as those related to the role played by the changing climate on height variations. This study, focused on the European and Mediterranean area, analyzed the GPS height time series of 114 well-distributed stations with the aim of identifying spatially coherent signals likely related to variations of environmental parameters, such as atmospheric surface pressure (SP) and terrestrial water storage (TWS). Linear trends and seasonality were removed from all the time series before applying the principal component analysis (PCA) to identify the main patterns of the space/time interannual variability. Coherent height variations on timescales of about 5 and 10 years were identified by the first and second mode, respectively. They were explained by invoking loading of the crust. Single-value decomposition (SVD) was used to study the coupled interannual space/time variability between the variable pairs GPS height–SP and GPS height–TWS. A decadal timescale was identified that related height and TWS variations. Features common to the height series and to those of a few climate indices—namely, the Arctic Oscillation (AO), the North Atlantic Oscillation (NAO), the East Atlantic (EA), and the multivariate El Niño Southern Oscillation (ENSO) index (MEI)—were also investigated. We found significant correlations only with the MEI. The first height PCA mode of variability, showing a nearly 5-year fluctuation, was anticorrelated (−0.23) with MEI. The second mode, characterized by a decadal fluctuation, was well correlated (+0.58) with MEI; the spatial distribution of the correlation revealed, for Europe and the Mediterranean area, height decrease till 2015, followed by increase, while Scandinavian and Baltic countries showed the opposite behavior.

Mediterranean forests responses to drought and forest fires: continuous monitoring through the TreeTalker system

2021 ◽  
Author(s):  
Francesco Niccoli ◽  
Arturo Pacheco-Solana ◽  
Simona Castaldi ◽  
Riccardo Valentini ◽  
Giovanna Battipaglia
Keyword(s):  
Forest Fires ◽  
Sap Flow ◽  
Regional Scale ◽  
Environmental Parameters ◽  
Absorption Capacity ◽  
Climatic Conditions ◽  
Severe Drought ◽  
Mediterranean Forests ◽  
Xylem Cavitation ◽  
The Mediterranean

&lt;p&gt;Forests play a key role in mitigating greenhouse gases and fighting climate change. However, numerous environmental stressors threaten the integrity and ecological functionalities of forests. In recent decades, the increase of drought events and fires occurrence is negatively influencing forest health, causing dieback events and higher rates of mortality, especially in the Mediterranean environments.&lt;/p&gt;&lt;p&gt;Studying the mechanisms of plants in response to these events and relating them to the duration and intensity of stress can be the key to understand the vulnerability and sensitivity at individual and regional scale. Currently, most of the available studies are severely limited in time and space, providing information with a relatively poor temporal resolution.&lt;/p&gt;&lt;p&gt;In this context, our research aims to examine the effects of these events on the ecophysiology of &lt;em&gt;Pinus pinaster&lt;/em&gt; Aiton, a very common conifer species in the Mediterranean environment, through the use of the innovative TreeTalker device (TT+). This instrument is able to monitor multiple physiological and environmental parameters of the tree such as sap flow, the amount of light absorbed by the canopy, meteorological information etc. The study is conducted in Southern Italy, more precisely at the Vesuvius National Park, affected in recent years by severe drought conditions and where a large wildfire occurred in July 2017. To evaluate the incidence of stress conditions, during the spring of 2020, 10 TT+ devices were installed in a pine stand affected by fire (Burned Site -BS) and 10 TT+ devices in a second stand called Control Site (CS) in which plants were not affected by the 2017 fire.&lt;/p&gt;&lt;p&gt;The preliminary monitoring data show interesting information about the hydraulic and stomatal strategies implemented by the trees on both stands according to the variation of the climatic conditions. While in the spring a rather regular sap flow trend was observed in both stands, during the summer months (July, August and good part of September), the trees show a reduction in their stomatal activity during the hottest hours of the day (11 am -15 pm), predictably as a mean to avoid episodes of xylem cavitation and to contrast the high temperatures. In the autumn months of October and November, however, vegetative activity has continued uninterrupted although a considerable decrease in hydraulic flow was registered. Finally, from the data collected it emerges that the severe reduction of the crown suffered by the plants of the BS has determined a lower absorption capacity of photosynthetic light, exposing these individuals to a greater possibility of carbon starvation.&lt;/p&gt;&lt;p&gt;The monitoring activities will continue for the next few years, allowing to understand better the eco-physiological dynamics leading the individuals of this species to overcome or succumb to stress events and/or extreme climatic conditions.&lt;/p&gt;

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