Search results for "seagrass"

Effectiveness of Posidonia oceanica biotic indices for assessing the ecological status of coastal waters in the Saronikos Gulf (Aegean Sea, Eastern M…

2017

Biotic indices are considered key assessment tools in most national and European policies aimed at improving the quality of coastal waters. At present, several Water Framework Directive (WFD)-compliant biotic indices based on the marine angiosperm Posidonia oceanica have been developed and applied in the Mediterranean Sea. In this study, we investigated the effectiveness of four different P. oceanica indices (POMI, PREI, Valencian CS, and BiPo) in evaluating the ecological status of coastal waters in a case study area of Greece. The evaluation, comparison, and validation of the Ecological Status Class (ESC) assessments obtained by each index were based on a set of eight common sites that en…

Response of seagrasses and marine biofilms to natural acidification at CO2 vents

Nel corso degli ultimi 200 anni, circa il 30% delle emissioni antropogeniche di CO2 nell’atmosfera sono state assorbite dagli oceani, provocando un abbassamento medio dei livelli di pH oceanici pari a circa 0.1 unità. Questo fenomeno, noto come acidificazione degli oceani, sta determinando conseguenze negative sugli ecosistemi marini e sul loro funzionamento. Le attuali proiezioni climatiche suggeriscono che, in futuro, i cambiamenti climatici continueranno e si intensificheranno se non verranno adottate efficaci misure di mitigazione. Riuscire a valutare la risposta degli ecosistemi marini ai cambiamenti climatici costituisce una vera sfida per la ricerca scientifica, non solo per la diffi…

Decomposition rate and invertebrate colonization of seagrass detritus along a hydrodynamic gradient in a Mediterranean coastal basin: The Stagnone di…

2019

International audience; Seagrass leaf litter decomposition is a key component of marine carbon flow driven by both biotic and abiotic factors, including water movement. In this study, we analyse Posidonia oceanica litter decomposition and invertebrate colonization in three sites with different hydrodynamics in a coastal basin. Litterbags were put on the sea bed along a gradient of distance from the open sea, implying a different level of water exchange. Leaf litter mass loss and carbon and nitrogen concentration were analysed, and density and biomass of benthic invertebrates colonizing litterbags were recorded after 3, 7, 14, 47, 101, 152 and 221 days. Results showed that in the most shelte…

Resistance of seagrass habitats to ocean acidification via altered interactions in a tri-trophic chain

2020

Despite the wide knowledge about prevalent effects of ocean acidification on single species, the consequences on species interactions that may promote or prevent habitat shifts are still poorly understood. Using natural CO2 vents, we investigated changes in a key tri-trophic chain embedded within all its natural complexity in seagrass systems. We found that seagrass habitats remain stable at vents despite the changes in their tri-trophic components. Under high pCO2, the feeding of a key herbivore (sea urchin) on a less palatable seagrass and its associated epiphytes decreased, whereas the feeding on higher-palatable green algae increased. We also observed a doubled density of a predatory wr…

Fish assemblages cope with ocean acidification in a shallow volcanic CO2 vent benefiting from an adjacent recovery area

2020

Shallow CO2 vents are used to test ecological hypotheses about the effects of ocean acidification (OA). Here, we studied fish assemblages associated with Cymodocea nodosa meadows exposed to high pCO2/low pH conditions at a natural CO2 vent in the Mediterranean Sea. Using underwater visual census, we assessed fish community structure and biodiversity in a low pH site (close to the CO2 vent), a close control site and a far control site, hypothesising a decline in biodiversity and a homogenization of fish assemblages under OA conditions. Our findings revealed that fish diversity did not show a unique spatial pattern, or even significant relationships with pH, but correlated with seagrass leaf …

Heavy Metal Contents in Soft-Bottom Marine Macrophytes and Sediments Along the Mediterranean Coast of Spain

2000

. Hg, Cd, Pb and Zn concentrations were determined in sediment and in tissues of five species of soft-bottom marine macrophytes (Posidonia oceanica, Cymodocea nodosa, Zostera noltii, Ruppia cirrhosa and Caulerpa prolifera) along the Spanish Mediterranean coast. Levels of metals were low in most of the sampling stations and similar to those found by other authors in uncontaminated zones. Certain locations, however, showed some degree of contamination (Cambrils, Almassora, Alacant, Mar Menor and El Portus). In Santa Pola we found high contents of metals in one sample of sediment due to the high proportion of the fine fraction (particules < 63µm) and organic matter, but not in the seagrass spe…

Life on the edge: Adaptations of Posidonia oceanica to hypersaline conditions in a Mediterranean lagoon system

2023

Hypersaline stress is a major stressor in semi-enclosed coastal lagoons, affecting the distribution and survival of key foundation species. In this study, we investigated how Posidonia oceanica meadows responded physiologically and morphologically to different salinity concentrations both in-situ, across a natural saline gradient occurring inside the lagoon system, and in a mesocosm experiment. Leaf water relations, organic osmolytes, photosynthesis, respiration, Chlorophyll-a fluorescence, pigments content, and leaf growth were studied in P. oceanica from three different sites within the Stagnone of Marsala lagoon, as well as after exposing P. oceanica to a salinity level of 46 psu in a 30…

BIOMASSA AND ACCUMULATION CARBON ON SEAGRASS Enhalus acroides IN GUNUNG BOTAK BAY COASTAL, WEST PAPUA

2018

Seagrass is a high level and a flowering plant that is fully adapted to life in the coastal and has ability to store carbon by 10% of the carbon content in the oceans. The research doing at Gunung Botak Bay Coastal South Manokwari Regency with objective of research to estimate seagrass density and to estimate rate accumulation of carbon from Enhalus acroides. Some the stages of the research done is density sample as long to period 2015 (April and Mei) into (September and Ocktober). Other sampling to collecting seagrass to estimate carbon storage in part like daun, rhizome root and substrat. Result to showing average carbon accumulation of seagrass in above below ground is rhizome part and h…

Studio della dinamica di decomposizione del detrito fogliare di Posidonia oceanica lungo un gradiente di confinamento in un’area siciliana a caratter…

2012

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

2014

12 páginas, 3 figuras