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 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 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 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

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 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 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 Unusually Warm Summer Temperatures Exacerbate Population and Plant Level Response of Posidonia oceanica to Anthropogenic Nutrient Stress

2021 ◽  
Vol 12 ◽  
Author(s):  
Stephanie B. Helber ◽  
Gabriele Procaccini ◽  
E. Fay Belshe ◽  
Alex Santillan-Sarmiento ◽  
Ulisse Cardini ◽  
...  
Keyword(s):  
Ecosystem Engineer ◽  
Population Level ◽  
Posidonia Oceanica ◽  
Anthropogenic Pressure ◽  
Nutrient Inputs ◽  
Area Index ◽  
Seagrass Meadows ◽  
Warm Summer ◽  
Summer Temperatures

Posidonia oceanica is a key foundation species in the Mediterranean providing valuable ecosystem services. However, this species is particularly vulnerable towards high coastal nutrient inputs and the rising frequency of intense summer heat waves, but their combined effect in situ has received little attention so far. Here, we investigated the effects of in situ nutrient addition during an unusually warm summer over a 4-month period, comparing different morphological, physiological and biochemical population metrics of seagrass meadows growing in protected areas (Ischia) with meadows already exposed to significant anthropogenic pressure (Baia – Gulf of Pozzuoli). Our study highlights that the effects of warmer than usual summer temperatures on the population level of seagrass meadows can be exacerbated if the plants are already exposed to higher anthropogenic pressures. Morphological and population level indicators mainly changed over time, possibly impacted by season and the warmer temperatures, and displayed more pronounced reductions in seagrasses from impacted sites. The additional nutrient supply had even more deleterious effects, as shown by a decrease in approximately 67% in cover in fertilized plots at high impacted sites and 33% at low impacted sites. Moreover, while rhizome starch concentration showed a seasonal increase in plants from low impacted sites it displayed a trend of a 27% decrease in fertilized plots of the high impacted sites. Epiphyte biomass was approximately four-fold higher on leaves of plants growing in impacted sites and even doubled with the additional nutrient input. Predicting and anticipating stress in P. oceanica is of crucial importance for conservation and management efforts, given the limited colonizing and reproductive ability and extremely slow growth of this ecosystem engineer. Our results suggest that monitoring efforts should focus especially on leaf area index (LAI), carbohydrate concentrations in the rhizomes, and epiphyte cover on leaves as indicators of the onset of stress in Posidonia oceanica, which can be used by decision makers to take appropriate measures before damage to the ecosystem becomes irreversible, minimize future human interference and strengthen the resilience of these important ecosystems.

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 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.

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