scholarly journals Seasonal Dynamic of CDOM in a Shelf Site of the South-Eastern Ligurian Sea (Western Mediterranean)

2020 ◽  
Vol 8 (9) ◽  
pp. 703
Author(s):  
Luca Massi ◽  
Laura Frittitta ◽  
Chiara Melillo ◽  
Francesca Polonelli ◽  
Veronica Bianchi ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Phytoplankton Biomass ◽  
Light Availability ◽  
Western Mediterranean ◽  
Taxonomic Composition ◽  
Seasonal Dynamic ◽  
Ligurian Sea ◽  
Positive Correlations ◽  
High Level

Chromophoric dissolved organic matter (CDOM) is the fraction of the Dissolved Organic Carbon (DOC) mainly absorbing UV and blue radiation, influencing water optical properties, light availability for primary production, and water-leaving radiance. In open seas, phytoplankton is the main source of organic carbon and CDOM. Despite this, the direct or indirect phytoplankton role in CDOM production is not yet fully clarified. From studies about the relationship between CDOM and phytoplankton biomass as Chlorophyll a (Chl) in the epipelagic layer, positive correlations have been highlighted with regional differences and high levels of variability. Seven years of seasonal dynamic and vertical distribution of CDOM in the Ligurian Sea continental shelf waters have been analyzed in order to evidence the main environmental and/or biological factors determining CDOM dynamic, focusing on the CDOM/Chl relationship. CDOM optical properties (absorption at 440 nm, aCDOM (440), and spectral slope, S) allowed to distinguish different pools and to debate their origin. Four different pools were characterized and two of them were directly or indirectly related to phytoplankton biomass and taxonomic composition. Nevertheless, CDOM/Chl confirm a high level of variability These findings suggest some inputs to improve Mediterranean satellite estimates of Chl and CDOM, such as the seasonal differentiation of optical properties, especially S and CDOM/Chl relationships.

scholarly journals Trade-offs Between Light and Nutrient Availability Across Gradients of Dissolved Organic Carbon Lead to Spatially and Temporally Variable Responses of Lake Phytoplankton Biomass to Browning

Ecosystems ◽  
2021 ◽  
Author(s):  
Peter D. F. Isles ◽  
Irena F. Creed ◽  
Anders Jonsson ◽  
Ann-Kristin Bergström
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Nutrient Availability ◽  
Phytoplankton Biomass ◽  
Light Availability ◽  
Nutrient Stoichiometry ◽  
Spatial Gradients ◽  
Trade Offs ◽  
Lower Light ◽  
The Relationship

AbstractNorthern lakes are experiencing widespread increases in dissolved organic carbon (DOC) that are likely to lead to changes in pelagic phytoplankton biomass. Pelagic phytoplankton biomass responds to trade-offs between light and nutrient availability. However, the influence of DOC light absorbing properties and carbon–nutrient stoichiometry on phytoplankton biomass across seasonal or spatial gradients has not been assessed. Here, we analyzed data from almost 5000 lakes to examine how the carbon–phytoplankton biomass relationship is influenced by seasonal changes in light availability, DOC light absorbing properties (carbon-specific visual absorbance, SVA420), and DOC–nutrient [total nitrogen (TN) and total phosphorus (TP)] stoichiometry, using TOC as a proxy for DOC. We found evidence for trade-offs between light and nutrient availability in the relationship between DOC and phytoplankton biomass [chlorophyll (chl)-a], with the shape of the relationship varying with season. A clear unimodal relationship was found only in the fall, particularly in the subsets of lakes with the highest TOC:TP. Observed trends of increasing TOC:TP and decreasing TOC:TN suggest that the effects of future browning will be contingent on future changes in carbon–nutrient stoichiometry. If browning continues, phytoplankton biomass will likely increase in most northern lakes, with increases of up to 76% for a 1.7 mg L−1 increase in DOC expected in subarctic regions, where DOC, SVA420, DOC:TN, and DOC:TP are all low. In boreal regions with higher DOC and higher SVA420, and thus lower light availability, lakes may experience only moderate increases or even decreases in phytoplankton biomass with future browning.

scholarly journals Biological production in two contrasted regions of the Mediterranean Sea during the oligotrophic period: An estimate based on the diel cycle of optical properties measured by BGC-Argo profiling floats

2021 ◽  
Author(s):  
Marie Barbieux ◽  
Julia Uitz ◽  
Alexandre Mignot ◽  
Collin Roesler ◽  
Hervé Claustre ◽  
...  
Keyword(s):  
Optical Properties ◽  
Organic Carbon ◽  
Water Column ◽  
Diel Cycle ◽  
Global Ocean ◽  
Ionian Sea ◽  
Biological Production ◽  
Ligurian Sea ◽  
Subsurface Chlorophyll Maximum ◽  
Mediterranean Systems

Abstract. This study assesses marine biological production of organic carbon based on the diel variability of bio-optical properties monitored by two BioGeoChemical-Argo (BGC-Argo) floats. Experiments were conducted in two distinct Mediterranean systems, the Northwestern Ligurian Sea and the Central Ionian Sea during summer months. We derived particulate organic carbon (POC) stock and gross community production integrated within the surface, euphotic and subsurface chlorophyll maximum (SCM) layers, using an existing approach applied to diel cycle measurements of the particulate beam attenuation (cp) and backscattering (bbp) coefficients. The diel cycle of cp provided a robust proxy for quantifying biological production in both systems; that of bbp was comparatively less robust. Derived primary production estimates vary by a factor of 2 depending upon the choice of the bio-optical relationship that converts the measured optical coefficient to POC, which is thus a critical step to constrain. Our results indicate a substantial, yet variable, contribution to the water column production of the SCM layer (16–42%). In the Ligurian Sea, the SCM is a seasonal feature that behaves as a subsurface biomass maximum (SBM) with the ability to respond to episodic abiotic forcing by increasing production. In contrast, in the Ionian Sea, the SCM is permanent, induced by phytoplankton photoacclimation and contributes moderately to water column production. These results emphasize the strong potential for transmissometers deployed on BGC-Argo profiling floats to quantify non-intrusively in situ biological production of organic carbon in the water column of stratified oligotrophic systems with recurring or permanent SCMs, which are widespread features in the global ocean.

scholarly journals Physiological and ecological consequences of the water optical properties degradation on reef corals

Coral Reefs ◽  
2021 ◽  
Author(s):  
Tomás López-Londoño ◽  
Claudia T. Galindo-Martínez ◽  
Kelly Gómez-Campo ◽  
Luis A. González-Guerrero ◽  
Sofia Roitman ◽  
...  
Keyword(s):  
Optical Properties ◽  
Population Decline ◽  
Light Availability ◽  
Potential Effect ◽  
Optical Quality ◽  
Light Penetration ◽  
Reef Corals ◽  
Orbicella Faveolata ◽  
Light Quantity ◽  
Reduced Light

AbstractDegradation of water optical properties due to anthropogenic disturbances is a common phenomenon in coastal waters globally. Although this condition is associated with multiple drivers that affect corals health in multiple ways, its effect on light availability and photosynthetic energy acquisition has been largely neglected. Here, we describe how declining the water optical quality in a coastal reef exposed to a turbid plume of water originating from a man-made channel compromises the functionality of the keystone coral species Orbicella faveolata. We found highly variable water optical conditions with significant effects on the light quantity and quality available for corals. Low-light phenotypes close to theoretical limits of photoacclimation were found at shallow depths as a result of reduced light penetration. The estimated photosynthetically fixed energy depletion with increasing depth was associated with patterns of colony mortality and vertical habitat compression. A numerical model illustrates the potential effect of the progressive water quality degradation on coral mortality and population decline along the depth gradient. Collectively, our findings suggest that preserving the water properties seeking to maximize light penetration through the water column is essential for maintaining the coral reef structure and associated ecosystem services.

Source, transport and fate of terrestrial organic carbon on the western Mediterranean Sea, Gulf of Lions, France

2007 ◽  
Vol 105 (1-2) ◽  
pp. 101-117 ◽  
Author(s):  
Tommaso Tesi ◽  
Stefano Miserocchi ◽  
Miguel A. Goñi ◽  
Leonardo Langone
Keyword(s):  
Organic Carbon ◽  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Gulf Of Lions ◽  
Western Mediterranean Sea

Food of striped dolphin, Stenella coeruleoalba, in the Ligurian Sea

1993 ◽  
Vol 73 (3) ◽  
pp. 571-578 ◽  
Author(s):  
M. Würtz ◽  
D. Marrale
Keyword(s):  
Mediterranean Sea ◽  
Western Mediterranean ◽  
Important Food ◽  
Ligurian Sea ◽  
Stenella Coeruleoalba ◽  
Striped Dolphin ◽  
Western Mediterranean Sea ◽  
Bony Fishes ◽  
Food Species ◽  
Ligurian Coast

The stomachsof 23 striped dolphins (Stenella coeruleoalba Meyen, 1833, Cetacea), stranded along the Ligurian coast (western Mediterranean Sea), contained 32 species of cephalopods, crustaceans and fishes, totalling an estimated 2,723 prey specimens representing about 36 kg in weight. Cephalopods and bony fishes were equally important in the diet (50%). Todarodes sagittatus (34.5%) and Micromesistius poutassou (25.9%) were found to be the most important food species. Other species belonging to six cephalopod families, three crustacean families and nine bony fish families, contributed to the diet with variable numbers, weights, and occurrences, demonstrating the opportunistic character of striped dolphin feeding.

scholarly journals Contribution of Terrestrial Runoff to Coral Disease Prevalence on North Bali’s Massive Porites

2017 ◽  
Vol 22 (4) ◽  
pp. 193
Author(s):  
I Gusti Bagus Siladharma ◽  
Widiastuti Karim
Keyword(s):  
Organic Carbon ◽  
Coral Disease ◽  
Environmental Parameters ◽  
Strong Relationship ◽  
Disease Prevalence ◽  
Terrestrial Runoff ◽  
Dominant Disease ◽  
Massive Porites ◽  
High Level ◽  
Organic Carbon Loading

The widespread of coral disease may threatened Bali`s marine tourism which is the main asset for the nation prosperity. However, the disease prevalence is still unknown, in particular inshore coral reefs near to tourist spot areas. Therefore, the research aims to investigate the contribution of terrestrial runoff to coral disease prevalence and to examine the relationships between disease prevalence and environmental parameters (nitrate, phosphate, organic carbon and total suspended solids (TSS)) within the population of massive Porites on shallow north Bali reefs. Syndrome, diseases and healthy colonies of massive Porites coral were counted and noted within a 2 x 10 m belt transect at 3 sampling sites. The dominant disease observed was ulcerative white spots (UWS), while the syndromes were pigmentation response and aggressive overgrowth by macroalgae. The highest mean UWS prevalence was at site 3 which was the closest site to runoff (prevalence = 91%).This disease only affected one colony at site 1 and 2, respectively. Disease prevalence had strong relationship with TSS and nitrate, yet it showed weak relationship with phosphate and organic carbon. These results suggest that terrestrial runoff could contribute to the disease prevalence by increasing the TSS, nutrients and organic carbon loading to the inshore ecosystems. High level of organic carbon could severe the disease, particularly when combined with elevated TSS and nutrient, by reducing the coral`s immunity system. Keywords: coral disease, prevalence, terrestrial runoff, Porites, ulcerative white spot, environmental parameter, North Bali.

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