Fig 1 - uploaded by David Balata
Content may be subject to copyright.
Source publication
Macroalgal assemblages of Posidonia oceanica rhizomes of the western Mediterranean have been studied, in order to describe the structure of this community and to evaluate changes due to recent macroalgal invasions. To achieve these objectives, P. oceanica rhizomes were sampled from 21 beds distributed throughout the western Mediterranean Sea and ma...
Context in source publication
Context 1
... meadows of Posidonia oceanica were sampled during summer 1997 and summer 1998. Nine were on the continental and insular coasts of Tuscany (Leghorn, Meloria, Vada, Baratti, Gorgona, Capraia, Elba, Giglio, Giannutri) and 12 in other parts of the western Mediterranean Sea (Minorca (Balearic Islands), Cabo de Creus (eastern Spain), Banyuls-sur-mer (western France), Esterel (eastern France), La Maddalena (Sardinia), Tonnara (Corsica), Civitavecchia (western Italy), Panarea (Aeolian Islands), Ustica, Pantelleria, Cap Bon (Tunisia) and Lampedusa) (Fig. 1). ...
Similar publications
Mediterranean Seagrasses are represented by five species, whose most representative are Posidonia oceanica (L.) Delile and Cymodocea nodosa (Ucria) Ascherson. Meadows of these two species have been also considered as priority habitat according Annex I of the EC Directive 92/43/EEC on the Conservation of Natural Habitats and of Wild Fauna and Flora...
Wide losses of Posidonia oceanica led some authors to suggest this species showed evidence of decline in a global scale. Our aim was to survey the long-term evolution of a healthy and mature meadow of Posidonia oceanica at Tabarca Island (SE, Spanish coast). We surveyed cover and density at three depths (-4, -12 and -20m) and the dynamics at border...
Changes of both macroalgal diversity and vegetational characteristics of the epiphytic macroalgal assemblage on Posidonia oceanica rhizomes of a meadow occurring at Marinkovac Island (central Adriatic Sea), following the invasion of Caulerpa racemosa var. cylindracea, are reported. The study was based on the comparison between epiphytic macroalgae...
Within-bed variation of epiphytic algal assemblages was studied in 3 Zostera marina beds around Plymouth Sound (Devon, United Kingdom) in order to determine if distance from edge of bed affected the assemblage composition. Replicate seagrass samples were taken at 0, 1, 3 and 6 m along a transect running from the edge of each bed. Individual epiphyt...
Citations
... While mechanisms resulting from direct responses of plants to herbivory pressure are relatively well explored in the literature, we found a raft of subtler indirect interactions that emerged as canopy height decreased with increasing herbivory. For a start, in meadows with heavily grazed, shorter canopies, sunlight can penetrate to the rhizome layer, promoting the growth of erect epiphytic algae (Boudouresque 1974, Piazzi et al. 2002. Our results suggest that the increased abundance of this alternative food resource can alleviate grazing pressure of P. lividus on seagrass leaves, likely constituting a buffering mechanisms that reduces grazing impact on P. oceanica. ...
... This mechanism might be particularly strong in MPAs, where fish populations are protected, but not operational in overfished areas. Similarly, the relevance of alternative preference mechanisms will depend on contextual factors that influence the abundance, diversity and growth of epiphytic algae on seagrass rhizomes, such as irradiance or nutrient availability (Piazzi et al. 2002, Balata et al. 2008, Nesti et al. 2009). This is clearly important for seagrass species that have large and long-lived rhizomes (i.e. ...
Plant–herbivore interactions are often regulated by a series of direct and indirect buffer mechanisms (compensatory or defensive plant responses, population control, alternative resources) that can determine the relative stability of the system. In plant-dominated marine environments, these mechanisms are particularly important given how vulnerable these systems are to strong consumer pressure. Here, we evaluate the presence and, where possible, the strength, of five mechanisms that get activated under high herbivory pressure and are capable of dampening their effects in a seagrass meadow ecosystem: 1) seagrass compensatory growth, 2) increase in plant resistance, 3) availability of alternative resources, 4) predatory control and 5) density-dependent control. We assessed these mechanisms for the interaction between the Mediterranean seagrass Posidonia oceanica and the sea urchin Paracentrotus lividus through a short-term series of controlled field and laboratory experiments after simulated or natural herbivory events. Of the five mechanisms tested, we found that three mechanisms – availability of alternative resources, increased predation rate and reduction in sea urchin numbers – effectively dampened herbivory and worked as potential buffering mechanisms. In contrast, plant compensatory growth and resistance did not show clear responses. While compensatory growth and plant resistance are direct plant mechanism to tolerate the effects of herbivory, the rest are indirect mechanisms that begin with a modification of a plant trait (i.e. canopy height) that influences other species preference and/or behaviour, which in turn influences plant consumption. These adaptive behaviours may be a crucial and often overlooked factor in the remarkable resilience that Mediterranean seagrass ecosystems show to herbivory. © 2023 Nordic Society Oikos. Published by John Wiley & Sons Ltd.
... Tale biocenosi è costituita dalla sovrapposizione di differenti popolamenti: quello fotofilo associato allo strato fogliare, e quelli sciafili associati ai rizomi e alla matte (Mazzella et al., 1989;Gambi et al., 1992;Buia et al., 2003). Le specie associate allo strato fogliare sono spesso esclusive delle foglie di P. oceanica (Figura 1.11); le specie associate ai rizomi, invece, non presentano elementi esclusivi e caratteristiche così peculiari, in quanto simili alle specie sciafile dell'infralitorale o del coralligeno circalitorale, in funzione della profondità e della quantità di luce corrispondenti (Figura 1.12) (Boudouresque, 1968;Piazzi et al., 2002). Fra le specie presenti all'interno della prateria si distinguono inoltre specie residenti e specie migratorie: le prime trascorrono l'intero ciclo vitale all'interno della prateria, mentre le seconde vi si trasferiscono dagli ambienti circostanti soltanto alla ricerca di cibo, di un riparo o per la riproduzione (Buia et al., 2000). ...
... The most dominant encrusting species were Hydrolithon and Pneophyllum species as epiphytes on the seagrass in the Mediterranean Sea (Jacquemart and Demoulin 2008;Piazzi et al. 2000). Only these two genera species predicted reasonably most of the ecological indications (Mann 2001;Lepoint et al. 2007;Peterson et al. 2007;Tsirika et al. 2007;Mabrouk et al. 2013;Bermejo et al. 2016;Mabrouk et al. 2017;Prado 2018;Sfriso et al. 2014Sfriso et al. , 2016Sfriso et al. , 2020 since they are very sensitive to change in the environments and common in undisturbed areas (Piazzi et al. 2002;Martinez-Crego et al. 2010;Bedini and Piazzi 2012;Brahim et al. 2020). The main indication of the encrusting micro calcareous has been focused on the acidification process in relation of the carbonate to the pH in the Mediterranean Sea (e.g. ...
Epiphytes on Posidonia oceanica play a crucial role for determination of the ecological status of marine environment in time and space besides the seagrasses alone. The study was aimed to estimate the spatiotemporal ecological status linked to variation in biometry of an epiphytic micro-calcareous red alga, Hydrolithon boreale found on leaves of the meadow with the exclusive environmental parameters along the entire Turkish coast of the Mediterranean Sea. Collection of Posidonia oceanica samples was conducted at 64 stations in winter (December 2018-January 2019) and 112 stations in summer (June-July 2019) by SCUBA (0.4 x 0.4 m of a quadrate frame) in the infralittoral zone along the entire Turkish Mediterranean coast surrounded by the siliciclastic Taurus Mountain Range which favor growth of epiphytic micro-calcareous red algae. Percent occurrence of the epiphyte changed seasonally; lower in winter (25%) than in summer (44%). The epiphyte which is indicator and sensitive to undisturbed marine area grew up well to 5 mm in diameter, 0.35 mm in thickness of the crust size, and was populated up to 1006 ind/m 2 in summer owing to the increased utilization of the carbonate by the epiphyte with the increased water temperature. The size was contrasted to the density (abundance and biomass) in space. The biometry was significantly dependent on the siliciclastic-carbonate deposition as inferred from SiO 4-Si of the water in relation to the leaf area index (LAI) of P. oceanica. Therefore, this deposition induced specimens to grow in size, followed by the reduced density concerning the N-based nutrient of the water. Further major environmental parameters which negatively affected the biometry were pH and total suspended matter of the water, analogous to turbidity. Of the trace elements, Ni was negatively correlated with the biometry whereas the LAI was however positively correlated with all the anthropogenic-sourced trace elements (V, Cu, Zn, As, Cd, and Pb) in the leaves. Of the bottom types, the calcite rock had a higher density than the other soft bottoms in contrast to the size of the epiphyte. Future studies could be based on the present study for determination of the ecological status regarding to two dominant epiphytes on leaves of two seagrasses (H. boreale on P. oceanica and partly Pneophyllum fragile on Cymodocea nodosa) found in the different environments and substrates in space and time.
... Le specie associate allo strato fogliare sono spesso esclusive delle foglie di P. oceanica; le specie associate ai rizomi, invece, non presentano elementi esclusivi e caratteristiche così peculiari, in quanto simili alle specie sciafile dell'infralitorale o del coralligeno circalitorale, in funzione della profondità e della quantità di luce corrispondenti ( fig. 1.7) (Piazzi et al., 2002;Boudouresque, 1968 Fra le specie presenti all'interno della prateria si distinguono inoltre specie residenti e specie migratorie: le prime trascorrono l'intero ciclo vitale all'interno della prateria, mentre le seconde vi si trasferiscono dagli ambienti circostanti soltanto per il tempo necessario alla ricerca di cibo, di un riparo o per la riproduzione (Buia et al., 2000). ...
... The species associated with the foliar layer are often exclusive to the leaves of P oceanica; the species associated with the rhizomes, on the other hand, do not present such distinctive exclusive elements and characteristics, as they are similar to the sciaphilic species of the infralittoral or circalittoral coralligenous zones, depending on the corresponding depth and quantity of light ( fig. 1.7) (Boudouresque, 1968;Piazzi et al., 2002). The species within the meadow include resident and migratory species: the former spend their entire life cycle inside the meadow, whereas the latter arrive from surrounding environments for the time necessary to search for food or shelter or to reproduce (Buia et al., 2000). ...
... E. M. Woll., a pesar de que presenta pocos registros y lleva sin detectarse desde el año 2015, se trata también de una especie con fuerte carácter invasor y que además es capaz de interactuar sinérgicamente con Womersleyella setacea (Hollenb.) R. E. Norris (recientemente detectada en las costas valencianas e invasora), aumentando así los impactos negativos que ejercen ambas sobre el hábitat (Piazzi & Cinelli 2000, Piazzi et al. 2002. Por lo que haría falta vigilar las zonas donde se han detectado estas especies y las áreas próximas a éstas para determinar el éxito de sus invasiones en dichas costas. ...
... E. M. Woll., a pesar de que presenta pocos registros y lleva sin detectarse desde el año 2015, se trata también de una especie con fuerte carácter invasor y que además es capaz de interactuar sinérgicamente con Womersleyella setacea (Hollenb.) R. E. Norris (recientemente detectada en las costas valencianas e invasora), aumentando así los impactos negativos que ejercen ambas sobre el hábitat (Piazzi & Cinelli 2000, Piazzi et al. 2002. Por lo que haría falta vigilar las zonas donde se han detectado estas especies y las áreas próximas a éstas para determinar el éxito de sus invasiones en dichas costas. ...
... E. M. Woll., a pesar de que presenta pocos registros y lleva sin detectarse desde el año 2015, se trata también de una especie con fuerte carácter invasor y que además es capaz de interactuar sinérgicamente con Womersleyella setacea (Hollenb.) R. E. Norris (recientemente detectada en las costas valencianas e invasora), aumentando así los impactos negativos que ejercen ambas sobre el hábitat (Piazzi & Cinelli 2000, Piazzi et al. 2002. Por lo que haría falta vigilar las zonas donde se han detectado estas especies y las áreas próximas a éstas para determinar el éxito de sus invasiones en dichas costas. ...
... Serpulid polychaetes are sessile organisms that colonize various marine habitats, from the shallow infralittoral to abyssal depths [29] and contain great taxonomic diversity [30]. Key drivers for the abundance and diversity of sessile polychaetes are environmental gradients (e.g., light and depth), as well as suitable space for larval settlement [19,31]. They contribute a considerable amount of carbonate bioconstructions from tropical to boreal latitudes, and shape the seafloor by acting as secondary builders [32,33]. ...
... marenzelleri), which resulted in a shared cluster disparate from the P. oceanica leaf samples (Figure 4). This clustering could be related to the two habitats' semi-hemisciaphilious conditions, which leads to reduced competition with algal epiphytes and influences rhizome communities [31]. Lower light conditions inside P. crispa mats and P. oceanica shoots are also reflected by the lower numbers of the photophilic Spirorbinae (e.g., Janua sp.) [59], mostly found on the leaves of P. oceanica. ...
The Mediterranean Sea harbors more than 17,000 eukaryotic marine species, with several ecosystems recognized as biodiversity hotspots, such as Posidonia oceanica meadows. Recent research indicates that benthic mats formed by the fleshy red alga Phyllophora crispa are also associated with high species richness. Among key groups found in these mats are sessile polychaetes, which live as epiphytes on the red algae thalli. Knowledge of abundance, species richness, and spatial variation of polychaetes associated with these habitats is still scarce. We carried out a comparative assessment focusing on serpulid polychaetes within samples from P. crispa mats and neighboring P. oceanica meadows at six different sampling sites around Giglio Island (Tyrrhenian Sea, Italy). A total of 17 serpulid taxa were identified. The abundance of serpulids (5665 individuals m−2 of P. crispa mat) were similar to neighboring P. oceanica meadows (2304 individuals m−2 leaves and 5890 individuals m−2 shoots). The number of serpulid taxa was significantly higher in P. crispa mats (average 6.63 ± 1.32 taxa) compared to P. oceanica beds (average 1.56 ± 0.63 and 1.84 ± 1.04 taxa in leaves and shoots, respectively). Within habitat type, there were no significant differences in species richness between sites. The most abundant species found was Josephella marenzelleri (61% of individuals), while Vermiliopsis spp. and Bathyvermilia sp. were exclusively found in P. crispa samples. Our results highlight that P. crispa mats host an exceptional diversity and that these habitats should be included in conservation strategies. Further research should focus on the significance of other important taxonomic groups within these mats and evaluate the distribution of P. crispa in different regions of the Mediterranean Sea.
... In fact, the topographic heterogeneity of the dead matte may enhance C. cylindracea spread, allowing favourable anchoring of rhizoids with a similar mechanism to that previously described for calcareous algae; moreover, the trapped sediment may represent a further source of nutrients for this rhizophitic alga (Piazzi et al., 2016). Similarly, W. setacea and A. preissii may easily colonize P. oceanica rhizomes Cinelli, 2000, 2001;Piazzi et al., 2002), but in the study area, their abundance remained low throughout the study period. Furthermore, macroalgal NIS invasion was significantly affected by depth, especially for filamentous Rhodophyta. ...
Since there is no local management for Marine Protected Areas (MPAs) to prevent the establishment of macroalgae NIS, successful efforts to contrast their spread probably should concentrate in the conservation of resistant habitats. The study aimed to evaluate the role of depth and habitat in the spread of macroalgal non-indigenous species (NIS). A multifactorial sampling design was employed to compare the abundance of NIS macroalgae over a one-year period across different substrates and depths within a Mediterranean MPArea. Moreover, the ecological quality of macroalgal assemblages in relation to invasion was assessed through the ALien Biotic IndEX (ALEX). The NIS macroalgae found in the MPA, Caulerpa cylindracea, Acrothamnion preissii, Womersleyella setacea and Falkenbergia sp., were overall quite low in abundance and, accordingly, the ALEX index had generally high values. The substrate, depth and time significantly affected NIS abundance; however, the lack of significant interannual variability (December 2018–December 2019), both in pooled and separated NIS abundance, suggested that the occurrence of these four NISs will no further expand in the MPA at the scale of habitat. The highlighted patterns in NIS abundance suggest the importance of detailed sampling designs of monitoring taking into consideration different habitats and depths and using suitable sampling methods to assess NIS establishment and spread, such as those required by international directives.
