scholarly journals Inter-annual variation of shoot density and biomass, nitrogen and phosphorus content of the leaves, and epiphyte load of the seagrass Posidonia oceanica (L.) Delile off Mallorca, western Mediterranean

2010 ◽  
Vol 75 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Jorge Terrados ◽  
Francisco Javier Medina-Pons
Keyword(s):  
Annual Variation ◽  
Phosphorus Content ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Western Mediterranean ◽  
Nitrogen And Phosphorus ◽  
Density And Biomass ◽  
Epiphyte Load

scholarly journals Trait gradients inform predictions of seagrass meadows changes to future warming

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Arianna Pansini ◽  
Gabriella La Manna ◽  
Federico Pinna ◽  
Patrizia Stipcich ◽  
Giulia Ceccherelli
Keyword(s):  
Global Warming ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Western Mediterranean ◽  
Seagrass Meadows ◽  
Western Mediterranean Sea ◽  
Seagrass Ecosystem ◽  
Rhizome Biomass ◽  
And Function ◽  
Time Substitution

AbstractComparing populations across temperature gradients can inform how global warming will impact the structure and function of ecosystems. Shoot density, morphometry and productivity of the seagrass Posidonia oceanica to temperature variation was quantified at eight locations in Sardinia (western Mediterranean Sea) along a natural sea surface temperature (SST) gradient. The locations are spanned for a narrow range of latitude (1.5°), allowing the minimization of the effect of eventual photoperiod variability. Mean SST predicted P. oceanica meadow structure, with increased temperature correlated with higher shoot density, but lower leaf and rhizome width, and rhizome biomass. Chlorophyll a (Chl-a) strongly impacted seagrass traits independent of SST. Disentangling the effects of SST and Chl-a on seagrass meadow shoot density revealed that they work independently, but in the same direction with potential synergism. Space-for-time substitution predicts that global warming will trigger denser seagrass meadows with slender shoots, fewer leaves, and strongly impact seagrass ecosystem. Future investigations should evaluate if global warming will erode the ecosystem services provided by seagrass meadows.

scholarly journals Photosynthetic activity buffers ocean acidification in seagrass meadows

2014 ◽  
Vol 11 (2) ◽  
pp. 333-346 ◽  
Author(s):  
I. E. Hendriks ◽  
Y. S. Olsen ◽  
L. Ramajo ◽  
L. Basso ◽  
A. Steckbauer ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Vertical Mixing ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Positive Trend ◽  
Coastal Zones ◽  
Carbonate System ◽  
Saturation State ◽  
Seagrass Meadows ◽  
Density And Biomass

Abstract. Macrophytes growing in shallow coastal zones characterised by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH changes in shallow (5–12 m) seagrass (Posidonia oceanica) meadows spanning 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr)) and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean, max and range pHNBS and max and range ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy) influenced max and min ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. Max and range ΩAr within the meadow showed a positive trend with the calcium carbonate load of the leaves, pointing to a possible link between structural parameters, ΩAr and carbonate deposition. Calcifying organisms, e.g. epiphytes with carbonate skeletons, may benefit from the modification of the carbonate system by the meadow. There is, however, concern for the ability of seagrasses to provide modifications of similar importance in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, on which LAI is based. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.

scholarly journals Photosynthetic activity buffers ocean acidification in seagrass meadows

2013 ◽  
Vol 10 (7) ◽  
pp. 12313-12346 ◽  
Author(s):  
I. E. Hendriks ◽  
Y. S. Olsen ◽  
L. Ramajo ◽  
L. Basso ◽  
A. Steckbauer ◽  
...  
Keyword(s):  
Metabolic Activity ◽  
Structural Parameters ◽  
Vertical Mixing ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Coastal Zones ◽  
Carbonate System ◽  
Saturation State ◽  
Seagrass Meadows ◽  
Density And Biomass

Abstract. Macrophytes growing in shallow coastal zones characterized by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH ranges is in shallow (5–12 m) seagrass (Posidonia oceanica) meadows from 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr) and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean and max pHNBS and max ΩAr. Oxygen production positively influenced the range and maximum pHNBS and the range of ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy) influenced ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. ΩAr was positively correlated with the calcium carbonate load of the leaves, demonstrating a direct link between structural parameters, ΩAr and carbonate deposition. There was a direct relationship between ΩAr, influenced directly by meadow LAI, and CaCO3 content of the leaves. Therefore, calcifying organisms, e.g. epiphytes with carbonate skeletons, might benefit from the modification of the carbonate system by the meadow. The meadow might be capable of providing refugia for calcifiers by increasing pH and ΩAr through metabolic activity. There is, however, concern for the ability of seagrasses to provide this refugia function in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, both strongly linked to LAI. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.

scholarly journals Trait Gradients Predict Global Warming Changes in Seagrass Meadows

2021 ◽  
Author(s):  
Arianna Pansini ◽  
Gabriella La Manna ◽  
Federico Pinna ◽  
Patrizia Stipcich ◽  
Giulia Ceccherelli
Keyword(s):  
Global Warming ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Western Mediterranean ◽  
Chl A ◽  
Seagrass Meadows ◽  
Western Mediterranean Sea ◽  
Rhizome Biomass ◽  
And Function ◽  
Time Substitution

Abstract Comparing populations across temperature gradients can inform how global warming will impact the structure and function of ecosystems. Shoot density, morphometry and productivity of the seagrass Posidonia oceanica to temperature variation was quantified at eight locations in Sardinia (western Mediterranean Sea) along a natural sea surface temperature (SST) gradient. The locations are spanned for a narrow range of latitude (1.5°), allowing the minimization of the effect of eventual photoperiod variability. Mean SST predicted P. oceanica meadow structure, with increased temperature correlated with higher shoot density, but lower leaf and rhizome width, and rhizome biomass. Chlorophyll a (Chl-a) strongly impacted seagrass traits independent of SST. Disentangling the effects of SST and Chl-a on seagrass meadow density revealed that they work independently, but in the same direction with potential synergism.Space-for-time substitution predicts that global warming will trigger denser seagrass meadows with slender shoots, fewer leaves, and strongly impact seagrass ecosystem. Future investigations should evaluate if global warming will erode the ecosystem services provided by seagrass meadows.

Density and distribution patterns of the endangered species Pinna nobilis within a Posidonia oceanica meadow in the Gulf of Oristano (Italy)

2010 ◽  
Vol 90 (5) ◽  
pp. 885-894 ◽  
Author(s):  
S. Coppa ◽  
I. Guala ◽  
G.A. de Lucia ◽  
G. Massaro ◽  
M. Bressan
Keyword(s):  
Marine Protected Area ◽  
Habitat Type ◽  
Distribution Patterns ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Western Mediterranean ◽  
Anthropogenic Pressure ◽  
Habitat Types ◽  
Pinna Nobilis ◽  
Key Factor

Pinna nobilis is an endemic bivalve of the Mediterranean Sea. In the last decades P. nobilis populations have declined drastically due to increasing anthropogenic pressure and it has been declared a protected species since 1992. Despite the need for conservation, knowledge of the ecology and monitoring of the main populations of P. nobilis are limited. This study considered a population living within a Posidonia oceanica meadow in the Gulf of Oristano (western Mediterranean, Italy). The study area, about 150 hectares, part of which is included within a Marine Protected Area and a Site of Community Importance, was subdivided in 3 sub-areas. The percentage cover of different habitat types (P. oceanica, dead matte and sand) in each sub-area was measured and meadow features (substrate coverage, matte compactness and shoot density) characterized. The hypotheses of differences in density, percentage of dead individuals, population structure, shell burial level and orientation of P. nobilis, were investigated according to sub-areas and to habitat type. The spatial distribution was patchy, and the habitat type resulted a key factor in determining both density and distribution. A strong edge effect was demonstrated: more than half of the observed individuals colonized the P. oceanica border. Matte compactness and shoot density were found to affect the density and distribution of P. nobilis. Shell burial level and percentage of dead individuals varied with sub-areas and habitat types. Size distribution was bimodal and common shell orientation was observed in two sub-areas. These results contribute to increase the knowledge of population ecology of this species and to provide useful information for implementing conservation policies.

Interpopulation variability of the reproductive cycle of Paracentrotus lividus (Echinodermata: Echinoidea) in the south-western Mediterranean

2000 ◽  
Vol 80 (5) ◽  
pp. 899-907 ◽  
Author(s):  
Mourad Guettaf ◽  
Gustavo A. San Martin ◽  
Patrice Francour
Keyword(s):  
Regional Scale ◽  
Gonad Index ◽  
Paracentrotus Lividus ◽  
Posidonia Oceanica ◽  
Western Mediterranean ◽  
Larval Phase ◽  
Spawning Period ◽  
Rocky Substrate ◽  
Maximum Value ◽  
Reproductive Cycles

The spawning of Paracentrotus lividus has been determined on the basis of the annual gonad index cycle at three sites in the Algiers area presenting low, intermediate and strong hydrodynamism. Three biotopes (Posidonia oceanica beds, rocky substrate with photophilous algae and overgrazed rocky substrate) and two depths (1–3 m and 6–10 m) were considered at these sites, the sex-ratio was always strongly in favour of females (2:1 to 3:1). In all sites but one, there were marked differences in the gonad index and the spawning period between sites; the gonad index reached its maximum value at the site with the weakest hydrodynamism, and the minimum value at the site with the strongest hydrodynamism. Spawning took place in April–May and August–September at the site with the weakest hydrodynamism, in April–June and October–December at the site with intermediate hydrodynamism and only in winter at the site with maximum hydrodynamism. The coexistence, on regional scale, of these reproductive cycles might enable Paracentrotus lividus to compensate the mortality during planktonic larval phase by the fact that spawning of this sea urchin occurred in all seasons.

Assessment of bioavailable nitrogen and phosphorus content in the sediments of Indian mangroves

2021 ◽  
Author(s):  
Yudhistir Reddy ◽  
Dipnarayan Ganguly ◽  
Gurmeet Singh ◽  
Mamidala Harikrishna Prasad ◽  
Paneer Selvam Arumughan ◽  
...  
Keyword(s):  
Phosphorus Content ◽  
Nitrogen And Phosphorus ◽  
Indian Mangroves
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