Hydrodynamic constraints to the seaward development of Posidonia oceanica meadows

Vacchi, Matteo; Montefalcone, Monica; Bianchi, Carlo Nike; Morri, Carla; Ferrari, Marco

doi:10.1016/j.ecss.2011.11.024

Cited by 51 publications

(52 citation statements)

References 39 publications

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“…Similar results were observed for algae by Gerard () and Vacchi et al . () as water motion also influences algae growth and production. Low flow velocities can limit boundary layer transport of dissolved gases and nutrients and, thus, result in reduced growth and production (Wheeler ; Parker , ).…”

Section: Discussionmentioning

confidence: 99%

Spatial scale variability in shoot density and epiphytic leaves ofPosidonia oceanicaon Kerkennah Island (Tunisia) in relation to current tide effects

et al. 2014

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A study was undertaken of the patterns of spatial variability, epiphytic biomass and distribution of epiphytic fauna and flora of Posidonia oceanica. Samples were taken at four stations located approximately 4 km apart, exposed to different current conditions. Stations A and B, situated near the Oued Mimoun tidal channel with its relatively strong bi‐directional flows, were affected by high current tide. The other two stations, North Oued Mimoun (L1) and South Oued Mimoun (L2), were located further from the channel, in low current tide conditions. Sampling was conducted in the Attaya area of Kerkennah Island (Tunisia) in August 2009 at depths between 2 and 3 m, with the results indicating differences among the stations. Shoot density decreased when exposed to high levels of hydrodynamic activity generated by current tides whereas the epiphytic biomass of P. oceanica leaves decreased at sheltered stations located far from the channel. Epiphytic algae such as Heterokontophyta, Rhodophyta and Chlorophyta, and epiphytic fauna represented by Bryozoa, Hydrozoa, Annelida, Porifera and Tunicata, dominated the epiphytic assemblages and were abundant at the station most exposed to high current tide hydrodynamics. Cyanobacteria, however, were dominant in stations exposed to low current tide.

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Section: Discussionmentioning

confidence: 99%

Spatial scale variability in shoot density and epiphytic leaves ofPosidonia oceanicaon Kerkennah Island (Tunisia) in relation to current tide effects

et al. 2014

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“…On the other hand, severe run-off during extreme rainfall events may negatively affect seagrass meadows causing sediment erosion or burial. Also, the expected alteration of the marine climate regime will imply changed coastal hydrodynamics, especially in term of intensity and frequency of wave action, with dramatic consequences for the positions of both the upper and lower limits of P. oceanica meadows (Vacchi et al, 2012).…”

Section: Decline Of Mediterranean Seagrass Meadowsmentioning

confidence: 99%

Climate change and Mediterranean seagrass meadows: a synopsis for environmental managers

Pergent¹,

Bazairi²,

Bianchi³

et al. 2014

Medit. Mar. Sci.

101

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This synopsis focuses on the effects of climate change on Mediterranean seagrasses, and associated communities, and on the contribution of the main species, Posidonia oceanica, to the mitigation of climate change effects through its role of sequestering carbon dioxide. Whilst the regression of seagrass meadows is well documented, generally linked to anthropogenic pressures, global warming could be a cause of new significant regressions, notably linked to the introduction of exotic species, the rise of Sea-Surface Temperature (SST), and relative sea level. Seagrass communities could also be affected by climate change through the replacement of seagrass species having high structural complexity by species of lower complexity and even by opportunistic introduced species. Although it is currently very difficult to predict the consequences of these alterations and their cascade effects, two main conflicting trends in the functioning of seagrass ecosystems that could occur are acceleration of the herbivore pathway or of the detritivore pathway. The mean net primary production of the dominant species, Posidonia oceanica, is relatively high and can be estimated to range between 92.5 to 144.7 g C m-2 a-1. Around 27% of the total carbon fixed by this species enters the sedimentary pathway leading to formation, over millennia, of highly organic deposits rich in refractory carbon. At the Mediterranean scale, the sequestration rate might reach 1.09 Tg C a-1. The amount of this stored carbon is estimated to range from 71 to 273 kg C m-2, which when considered at the Mediterranean scale would represent 11 to 42% of the CO2 emissions produced by Mediterranean countries since the beginning of the Industrial Revolution. The greatest value of the P. oceanica ecosystem, in the context of mitigation of global climate change, is linked to this vast long-term carbon stock accumulated over the millennia, and therefore, efforts should be focused on preserving the meadows to keep this reservoir intact.

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“…Specifically, waves have been found to determine the upper (Infantes et al 2009) and lower (Vacchi et al 2012) depth distribution limits of P. oceanica and can also influence species, size and morphology (Lewis 1968, Menge 1976, Blanchette 1997. Several studies have demonstrated wave attenuation by P. oceanica meadows.…”

Section: Introductionmentioning

confidence: 99%

Impact of anthropogenically created canopy gaps on wave attenuation in a Posidonia oceanica seagrass meadow

Colomer¹,

Soler²,

Serra³

et al. 2017

Mar. Ecol. Prog. Ser.

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Fixed weights moorings, once removed, can create longitudinal gaps in seagrass meadows of different sizes, running perpendicular to the coast. We quantified the interactions between these longitudinal gaps and the hydrodynamic environment of the nearshore environment to determine their potential impact on seagrass meadow ecology. Within the meadow at leaf length distances from the edge, wave attenuation by the lateral vegetation next to the gap was approximately the same as attenuation by fully vegetated areas, and the wave attenuating capacity of the lateral, near-gap vegetation was independent of gap width. Gaps with widths less than twice the leaf length exhibited 8% wave attenuation and 11% turbulent kinetic energy attenuation, confirming that vegetation shelters at least small gaps. Despite similar capacity for wave attenuation, the longitudinal gaps influenced the architectural characteristics of the adjacent (lateral) meadow; lateral shoot density, percent cover and leaf length adjacent to the largest gap were 12, 16, and 20% lower than the fully vegetated site, respectively. Significant differences in the temporal variation of the mean lateral, near-gap seagrass percent cover and the leaf length indicated a strong dependence of the state of the canopy on temporal hydrodynamic conditions, which in turn were impacted by the presence of the gap. Our results quantify the interactions between gaps and lateral meadow vegetation, highlight the structural impact of traditional moorings and support improved management and conservation of seagrass meadows.

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Hydrodynamic constraints to the seaward development of Posidonia oceanica meadows

Cited by 51 publications

References 39 publications

Spatial scale variability in shoot density and epiphytic leaves ofPosidonia oceanicaon Kerkennah Island (Tunisia) in relation to current tide effects

Spatial scale variability in shoot density and epiphytic leaves ofPosidonia oceanicaon Kerkennah Island (Tunisia) in relation to current tide effects

Climate change and Mediterranean seagrass meadows: a synopsis for environmental managers

Impact of anthropogenically created canopy gaps on wave attenuation in a Posidonia oceanica seagrass meadow

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