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 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.

scholarly journals The Management of the Beach-Cast Seagrass Wracks—A Numerical Modelling Approach

2020 ◽  
Vol 8 (11) ◽  
pp. 873
Author(s):  
Andrea Cucco ◽  
Giovanni Quattrocchi ◽  
Walter Brambilla ◽  
Augusto Navone ◽  
Pieraugusto Panzalis ◽  
...  
Keyword(s):  
Winter Season ◽  
Numerical Approach ◽  
Posidonia Oceanica ◽  
Western Mediterranean ◽  
Western Mediterranean Sea ◽  
Hydrodynamic Wave ◽  
Selection Of ◽  
Beach Cast ◽  
Modelling Approach

Seagrass wrack are commonly found on the beach face of the sandy shore all around the world and often persists in situ during the whole year, favouring the emergence of conflicts for the use of the sandy coasts for bathing or for other recreational purposes. As a consequence, these deposits are often removed from the beach during the summer months, temporary stocked, and relocated on the shore face in the next autumn or winter season. The selection of the sites on the shoreline where the leaves should be released before the storms season is often an issue, considering the optimization needs between the transportation costs and the oceanographic features of the dumping site. In this study, a numerical approach was proposed to identify the most suitable areas for the autumnal repositioning of the seagrass wracks for two beaches of Sardinia, an island located in the Western Mediterranean Sea where Posidonia oceanica (L. Delile, 1813) is the most widespread seagrass species. The method is based on the use of hydrodynamic, wave, and particle tracking models and provides important indications useful for the management of this type of practice that can be extended to all different type of beaches along the Mediterranean coasts.

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 Monitoring of Posidonia oceanica meadows in the Telašćica Nature Park (Croatia)

2015 ◽  
Author(s):  
Zrinka Jakl ◽  
Milena Šijan ◽  
Mosor Prvan ◽  
Maya Sertic ◽  
Vanja Čavrak ◽  
...  
Keyword(s):  
High Pressure ◽  
A Priori ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Management Plan ◽  
Anthropogenic Pressure ◽  
Project Assessment ◽  
Seagrass Meadows ◽  
Combined Use ◽  
Nature Park

Monitoring of marine priority habitats has been recently undertaken in the Telašćica Nature Park (Croatia) in compliance with the management plan developed within the MedPAN South project. Assessment of the state of Posidonia oceanica meadows was made in 2011, 2012 and 2014, in five locations subjected to different anthropogenic pressure. The monitoring was mainly aimed to establish the presence of disturbance in locations that are highly frequented by recreational boaters. Using an empirical assessment of frequent boat use, meadows were defined as “anchoring” (four locations - Čuška Dumboka, Kobiljak, Lučica, Sestrica – that are potentially subjected to high pressure from boating activities) or “no-anchoring” (one location - Garmenjak - where boating activites are considered negligible since the area is not a preferred destination for boater). Structural descriptors of the meadows (i.e shoot density and the Conservation Index) were assessed at different sites at each location, by means of direct surveys in SCUBA diving. Results indicate clear signs of deterioration at the locations that are subjected to high pressure of anchoring. Overall, shoot density at the "no-anchoring" sites had significant higher values than the "anchoring" sites, by around 31% to 45% higher, over the three years of investigations. Changes in values of the Conservation Index were smaller; 10% to 15% higher in “no-anchoring” than "anchoring" sites. Among the “anchoring” locations, Čuška Dumboka and Kobiljak showed the lowest values of shoot density and Conservation Index (as a consequence of the highest cover of dead matte), over the three years of monitoring. The combined use of the two descriptors seems to be effective in obtaining information on the condition of the seagrass meadows and strengthens the a priori assumption that mechanical disturbance of anchors affects P. oceanica adversely by enhancing regression of the meadows. The management authority is now implementing a series of actions to reduce human pressures and promote a more sustainable approach to nautical tourism. Monitoring of boating frequency and activities (number and size of boats, anchor type), is recommended to assess the effective pressure of anchoring and understand whether the different conditions of meadows under pressure correspond to the different levels of disturbance or if other factors along with anchoring are influencing the seagrass beds.

scholarly journals Polychaetes associated with Posidonia oceanica meadows along a gradient of ocean acidification at a CO2 vent system (Ischia, Italy)

2015 ◽  
Author(s):  
Maria Cristina Gambi ◽  
Erica Keppel ◽  
Rosanna Guglielmo ◽  
Adriana Giangrande ◽  
Samantha L. Garrard
Keyword(s):  
Ocean Acidification ◽  
Feeding Habits ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Low Ph ◽  
Marine Biota ◽  
The South ◽  
South Side ◽  
Seagrass Meadows ◽  
Ph Conditions

Polychaetes represent one of the most diversified and abundant taxa associated with seagrass meadows. These organisms show various feeding habits at different levels of the complex seagrass food web, representing suitable bioindicators of meadow structure and environmental status and disturbances. Ocean acidification (OA) is today considered one of the most pervasive stressors for marine biota at the level of species, communities and ecosystems. Naturally acidified systems, such as CO2 vents, represent suitable natural laboratories to study the effects of OA on benthic organisms. An analysis of polychaetes associated with Posidonia oceanica meadows located around shallow CO2 vents off the island of Ischia, is presented here. Polychaetes were collected in November 2011 with an air-lift sampler (40x40 cm; 4 replicates per station) along a gradient of OA at the Castello’s vent system at six stations (3 on the south and 3 on the north side), ranging from extreme low pH conditions (mean pH 7.5 occurring only on the south side) to control, normal pH conditions (8.12); a further control station was considered, 600 m from the Castello in similar environmental conditions and ambient pH (S. Anna meadow). A total of 99 taxa and about 4200 individual polychaetes were collected. Taxa richness showed higher values in the acidified stations, especially on the south side; similarly abundances were from two- to four-fold higher under low and extreme low pH conditions, in respect to control ones, due to relatively few dominant taxa. These are represented by Amphiglena mediterranea, Syllis gerlachi, S. prolifera, Exogone dispar, Sphaerosyllis pirifera, Polyophthalmus pictus and Kefersteinia cirrata. Multivariate analysis showed a separation between control and low pH assemblages and a separation between low pH and the extreme low pH site on the south side. Control stations showed higher variability among replicates, while acidified stations, especially those under extreme low pH conditions, showed a more homogeneous assemblage structure. These results demonstrate that many species of polychaetes are robust to OA, however, the high seagrass shoot density, occurring at acidified stations, may buffer the negative effect of this stressor on the biota, and explain both the high diversity and abundance observed there.

scholarly journals Monitoring of Posidonia oceanica meadows in the Telašćica Nature Park (Croatia)

2015 ◽  
Author(s):  
Zrinka Jakl ◽  
Milena Šijan ◽  
Mosor Prvan ◽  
Maya Sertic ◽  
Vanja Čavrak ◽  
...  
Keyword(s):  
High Pressure ◽  
A Priori ◽  
Posidonia Oceanica ◽  
Shoot Density ◽  
Management Plan ◽  
Anthropogenic Pressure ◽  
Project Assessment ◽  
Seagrass Meadows ◽  
Combined Use ◽  
Nature Park

Monitoring of marine priority habitats has been recently undertaken in the Telašćica Nature Park (Croatia) in compliance with the management plan developed within the MedPAN South project. Assessment of the state of Posidonia oceanica meadows was made in 2011, 2012 and 2014, in five locations subjected to different anthropogenic pressure. The monitoring was mainly aimed to establish the presence of disturbance in locations that are highly frequented by recreational boaters. Using an empirical assessment of frequent boat use, meadows were defined as “anchoring” (four locations - Čuška Dumboka, Kobiljak, Lučica, Sestrica – that are potentially subjected to high pressure from boating activities) or “no-anchoring” (one location - Garmenjak - where boating activites are considered negligible since the area is not a preferred destination for boater). Structural descriptors of the meadows (i.e shoot density and the Conservation Index) were assessed at different sites at each location, by means of direct surveys in SCUBA diving. Results indicate clear signs of deterioration at the locations that are subjected to high pressure of anchoring. Overall, shoot density at the "no-anchoring" sites had significant higher values than the "anchoring" sites, by around 31% to 45% higher, over the three years of investigations. Changes in values of the Conservation Index were smaller; 10% to 15% higher in “no-anchoring” than "anchoring" sites. Among the “anchoring” locations, Čuška Dumboka and Kobiljak showed the lowest values of shoot density and Conservation Index (as a consequence of the highest cover of dead matte), over the three years of monitoring. The combined use of the two descriptors seems to be effective in obtaining information on the condition of the seagrass meadows and strengthens the a priori assumption that mechanical disturbance of anchors affects P. oceanica adversely by enhancing regression of the meadows. The management authority is now implementing a series of actions to reduce human pressures and promote a more sustainable approach to nautical tourism. Monitoring of boating frequency and activities (number and size of boats, anchor type), is recommended to assess the effective pressure of anchoring and understand whether the different conditions of meadows under pressure correspond to the different levels of disturbance or if other factors along with anchoring are influencing the seagrass beds.

scholarly journals Sedimentary facies and foraminiferal assemblages from Posidonia oceanica meadows of western Mediterranean Sea

2015 ◽  
Author(s):  
Giovanni Gaglianone ◽  
Virgilio Frezza ◽  
Marco Brandano
Keyword(s):  
Mediterranean Sea ◽  
Weighted Average ◽  
Sedimentary Facies ◽  
Posidonia Oceanica ◽  
Western Mediterranean ◽  
Carbonate Content ◽  
Western Mediterranean Sea ◽  
Set Up ◽  
Giglio Island ◽  
Very High Frequencies

Sedimentary facies and foraminiferal assemblages of sediments sampled into seven Posidonia oceanica meadows from Western Mediterranean Sea were investigated. Six sampling sites are localised in Italy (Maratea, Ponza Island, Santa Marinella, Giglio Island, Osalla and Alghero), and one in France (Argentella, Crovani Bay, Corsica). The role of P. oceanica meadows in the sedimentary processes was investigated in different contexts: sampled meadows are set up both on soft and hard substrates, often forming “mattes”, in geographical areas subject to different wind and sea conditions (waves and longshore currents) and characterised by various coastal landforms and terrigenous inputs derived from costal erosional processes and/or fluvial contributions. A sedimentological, compositional, micropaleontological and geochemical characterisation of 111 bottom sediment samples, collected by SCUBA diving between 0 and 35 mwd, was carried out and finally tested with a Q-mode cluster analysis. Five sedimentary facies have been recognised, from terrigenous to mixed siliciclastic-carbonate and carbonate. Facies (and subfacies) are distinguishable by sorting, gravel content, abundance and maturity of clastic sediments, and weighted average of carbonate content. In all facies, foraminifers and red algae dominate the bioclastic fraction, whereas other bioclastic components are very subordinate and show a variable distribution. In all the investigated sites, benthic foraminiferal assemblages are generally dominated by typical epiphytic species, such as Asterigerinata mamilla, Lobatula lobatula, Peneroplis pertusus, Planorbulina mediterranensis, Rosalina spp. and miliolids. Nevertheless, these assemblages show some differences in the different sites according to the presence or absence of terrigenous contributions and, consequently, to the water turbidity. This parameter influences symbiont-bearing foraminifer as P. pertusus. Moreover, the samples from Argentella (Crovany Bay) are characterised by a peculiar assemblage, in which Miniacina miniacea dominates with very high frequencies.

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