Article

Status of vulnerable Cystoseira populations along the Italian infralittoral fringe, and relationships with environmental and anthropogenic variables

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Abstract

We analyzed the occurrence and status of infralittoral fringe populations of Cystoseira spp. (Fucales) at thirteen rocky sites around the Italian coastline, and explored the relationships with relevant environmental and anthropogenic variables. We found Cystoseira populations at 11 sites: most were scattered and comprised monospecific stands of C. compressa, and only 6 sites also supported sparse specimens of either C. amentacea var. stricta or C. brachycarpa. Coastal human population density, Chlorophyll a seawater concentrations, sea surface temperature, annual range of sea surface temperature and wave fetch explained most of the variation of the status of C. compressa. We hypothesize a generally unhealthy state of the Italian Cystoseira infralittoral fringe populations and identify multiple co-occurring anthropogenic stressors as the likely drivers of these poor conditions. Extensive baseline monitoring is needed to describe how Cystoseira populations are changing, and implement a management framework for the conservation of these valuable but vulnerable habitats.

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... Expanding global human impacts and climate change have contributed to disrupting the ecology and distribution of marine algae, with detrimental consequences on the algae themselves, other living marine resources, ma-rine ecosystems, human health and human activities. Examples of disruptions and imbalances include: a) ocean warming and acidification affecting the ecophysiology, lifecycle, zonation and biogeographic distribution of marine algae (Mancuso et al., 2018); b) pollution altering water pH and compromising settlement, photosynthesis, growth and other processes in marine algae (Contreras-Porcia et al., 2017); c) overharvesting and overfishing removing marine algae or resulting in cascade effects including increased herbivory of marine algae (Mac Monagail et al., 2017;Pinna et al., 2020); d) introducing marine algae into new areas, for example by maritime traffic (Orlando-Bonaca et al., 2019;Najdek et al., 2020); and e) harmful algal blooms caused by pollution and eutrophication (Griffith & Gobler, 2020). ...
... The canopy-forming brown algae of the genus Cystoseira are important ecosystem engineers along rocky shores. Highly vulnerable to anthropogenic stressors, they represent useful ecological indicators of water and ecosystem quality based on the Water Framework Directive (2000/60/ EC) (Mancuso et al., 2018). Recreational divers have been monitoring Cystoseira using protocols of citizen science in the Mediterranean Sea, such as Reef Check (Mannino et al., 2021). ...
... These concerns match what are generally known to be critical stressors on marine algae (Grattan et al., 2016;Mancuso et al., 2018;Griffith & Gobler, 2020). ...
Article
Marine algae offer numerous extrinsic and intrinsic ecosystem services. Human impacts and climate change, however, have contributed to disrupting or compromising their ecology and distribution. Continuing research and monitoring of marine algae are pivotal but require public support. This study investigated public knowledge of and attitude towards marine algae and support for their research and monitoring. The focus was coastal users, a diversified group of interest for research into the perceptions of marine algae. The study was carried out in the Conero Riviera (Adriatic Sea, Italy), a location where coastal users come into contact with several types of marine algae. Semi-structured interviews were conducted in 2020 with 202 randomly selected scuba divers, beach and promenade visitors in the Riviera. Data analysis was thematic and statistical. Participants possessed basic knowledge of marine algae, which was more sophisticated among scuba divers. Coastal users ascribed both extrinsic and intrinsic values to marine algae. Most participants recognised the importance of protecting and managing marine algae while supported research and monitoring, prioritising types of marine algae which provide specific extrinsic and intrinsic ecosystem services. Based on the results, strategies of outreach, communication and engagement are suggested for the study location and types of coastal users. This study contributed to the growing body of research on Ocean Literacy, confirming the importance of investigating perceptions of marine resources to steer research, management and outreach strategies.
... Macroalgal forests represent a paradigmatic example of key threatened benthic habitat featured by sparse but increasing spatial information, deserving further efforts to improve the management of those pressures determining their increasing loss across the Mediterranean and elsewhere (Benedetti-Cecchi et al., 2001). Macroalgal forests are one of the most productive and valuable, yet undervalued habitats, undergoing dramatic changes (Mangialajo et al., 2008;Thibaut et al., 2005Thibaut et al., , 2015Blanfuné et al., 2016;Mancuso et al., 2018). Along temperate rocky coasts worldwide, large canopy-forming algae (Laminariales and Fucales) were dominant in both intertidal and subtidal habitats, providing shelter, food and nursery areas to a multitude of marine communities, increasing three-dimensional complexity and spatial heterogeneity of rocky substrates, enhancing biodiversity and productivity in coastal ecosystems (Ballesteros et al., 1998;Fowler-Walker and Connell, 2002;Steneck et al., 2002;Cheminée et al., 2013;Gianni et al., 2013;Gorman et al., 2013;Piazzi et al., 2018). ...
... Despite the limits, the chosen approach based on the RF technique allowed us to highlight the most relevant predictor variables affecting the HSM and therefore those variables better candidates to explain Cystoseira canopies distribution and potential for regression. Considering both the importance measures obtained as RF outputs, the topographic coastal slope and the nature of substrate along the coast were identifies as the main factors in controlling Cystoseira canopies distribution, in accordance with the specific coastal conditions required for the infralittoral species development, limited to intertidal and shallow subtidal rocky shores (ESRI, 2012;Mancuso et al., 2018). Some anthropogenic variables emerged as relatively important from this analysis, but they followed the importance of the geomorphological ones. ...
... Finally, environmental variables, such as the distance to river mouths, the euphotic depth, the diffuse attenuation coefficient, the mean of chlorophyll a and the nitrate concentration, also displayed a significant role in the RF growth. Actually, these predictors can be regarded as indicators of nutrient enhancement, water turbidity and eutrophication levels which are included in several studies amongst the main causes for the regression of Cystoseira species (Cormaci and Furnari, 1999;Arévalo et al., 2007;Sales and Ballesteros, 2009;Fraschetti et al., 2011;Sala et al., 2012;Mancuso et al., 2018). Nevertheless, attention should be drawn to the fact that RF, given its potential to reflect the resemblance between the local spatial structure of predictor variables and species distribution, does not allow to reveal causal relationships. ...
Article
Full-text available
Macroalgal forests are one of the most productive and valuable marine ecosystems, but yet strongly exposed to fragmentation and loss. Detailed large-scale information on their distribution is largely lacking, hindering conservation initiatives. In this study, a systematic effort to combine spatial data on Cystoseira C. Agardh canopies (Fucales, Phaeophyta) was carried out to develop a Habitat Suitability Model (HSM) at Mediterranean scale, providing critical tools to improve site prioritization for their management, restoration and protection. A georeferenced database on the occurrence of 20 Cystoseira species was produced collecting all the available information from published and grey literature, web data portals and co-authors personal data. Data were associated to 55 predictor variable layers in the (ASCII) raster format and were used in order to develop the HSM by means of a Random Forest, a very effective Machine Learning technique. Knowledge about the distribution of Cystoseira canopies was available for about the 14% of the Mediterranean coastline. Absence data were available only for the 2% of the basin. Despite these gaps, our HSM showed high accuracy levels in reproducing Cystoseira distribution so that the first continuous maps of the habitat across the entire basin was produced. Misclassification errors mainly occurred in the eastern and southern part of Frontiers in Marine Science | www.frontiersin.org 1 February 2020 | Volume 7 | Article 20 Fabbrizzi et al. Modeling Macroalgal Forest Distribution the basin, where large gaps of knowledge emerged. The most relevant drivers were the geomorphological ones, followed by anthropogenic variables proxies of pollution and urbanization. Our model shows the importance of data sharing to combine a large number of spatial and environmental data, allowing to individuate areas with high probability of Cystoseira occurrence as suitable for its presence. This approach encourages the use of this modeling tool for the prediction of Cystoseira distribution and for supporting and planning conservation and management initiatives. The step forward is to refine the spatial information of presence-absence data about Cystoseira canopies and of environmental predictors in order to address species-specific assessments.
... In last decades, declines or loss of Cystoseira populations have been observed from many rocky coasts particularly close to urban areas due to combined effects of anthropogenic impacts such as pollution, urbanization, overfishing and climate-change (Benedetti-Cecchi et al., 2001;Thibaut et al., 2005;Arevalo et al., 2007b;Mangialajo et al., 2008;Strain et al., 2014;Mineur et al., 2015;Mancuso et al., 2018;Blanfuné et al., 2019). As consequence, many coastal systems showed a drastic shift from complex and productive benthic communities to less structured assemblages dominated by turf-forming algae, mussels or sea urchin barrens (Benedetti-Cecchi et al., 2001;Connell et al., 2014;Strain et al., 2014;Agnetta et al., 2015;Mineur et al., 2015;Krumhansl et al., 2016). ...
... Cystoseira forests form some of the most diverse and productive habitats along the rocky coasts of the Mediterranean Sea. Evidence reports both the retraction and loss of Cystoseira, particularly due to a compound effect of anthropogenic and climate-change stressors (Benedetti-Cecchi et al., 2001;Thibaut et al., 2005;Arevalo et al., 2007a;Mangialajo et al., 2008;Strain et al., 2014;Mineur et al., 2015;Mancuso et al., 2018;Blanfuné et al., 2019). This triggers cascading effects on associated biodiversity and ecosystem services (Mineur et al., 2015;Buonomo et al., 2018;De La Fuente et al., 2019). ...
Article
Canopy-forming seaweeds of the genus Cystoseira (Fucales, Phaeophyceae) form diverse and productive habitats along temperate rocky coasts of the Mediterranean Sea. During the last decade, Cystoseira forests have retracted their range considerably due to many interacting environmental, biological and anthropogenic pressures. We investigated how reducing in patch-size of C. montagnei affects their associated molluscan communities at the shallow northwest rocky shores of Palermo (Sicily, Italy). Molluscs were sampled from the fronds of individual thalli, clumps of 3 and 5 thalli of C. montagnei over an annual vegetative cycle (May–September) in two sites within the Marine Protected Area “Capo Gallo-Isola delle Femmine”. We measured five substrate attributes of the alga (thallus volume, canopy volume, interstitial volume, algal surface, and biomass) and explored their relationships with the diversity of the associated molluscan assemblage. A total of 3756 individuals of molluscs were collected, belonging to 30 families and 57 species, being Rissoidae the most speciose family and Barleeidae the dominant in terms of abundance. The molluscan assemblage on C. montagnei displayed significant spatial and seasonal variations, with the maximum number of individuals and species in summer, whereas evenness and diversity displayed maximum values in spring. The abundance, species richness and diversity of the molluscan assemblage decreased with decreasing in patch-size of C. montagnei, regardless of the vegetative phase of the alga or the sites considered in the study, while evenness showed an opposite trend. The substrate attributes of C. montagnei changed over the vegetative cycle of the alga and showed a similar pattern across sites with values that tended to decrease in autumn during the quiescence phase of the alga. Variation in patch-size of C. montagnei affected also the substrate attributes of the individual alga, with individual thalli becoming smaller with increasing patch-size. The algal surface of a single thallus of C. montagnei ranged on average from 956 cm2 in spring to 289 cm2 in autumn. Furthermore, algal surface together with thallus volume and dry weight were the substrate attributes that explained better the variation of the number of molluscan individuals and species. Overall, our results suggest that the reduction of both patch-size and algal substrate of C. montagnei forests altered the structure and composition of its associated molluscan assemblage. We argue that a reduction or loss of Cystoseira forests could probably trigger bottom-up effects in rocky shores habitats, with consequences for the whole ecosystem structure, functioning and services provided to humans.
... For instance, C. amentacea var. stricta, T. algeriensis and C. compressa, with large productive potential, require light saturation [57] and high hydrodynamism [13,27,31,37,58,59]. Consequently, they are frequently found in rifts and other exposed places. ...
... Cystoseira sl evolution data would generate time series to know the state of these communities, thus evaluating the health of our coast. This type of study is already being carried out in different areas of the Mediterranean Sea [20,31,59,76]. ...
Article
Full-text available
Cystoseira sensu lato (sl) are three genera widely recognized as bioindicators for their restricted habitat in a sub-coastal zone with low tolerance to pollution. Their ecological, morphological and taxonomic features are still little known due to their singular characteristics. We studied seven species of Cystoseira sl spp. in Cabo de las Huertas (Alicante, SE Spain) and analyzed their distribution using Permutational Analysis of Variance (PERMANOVA) and Principal Component Ordination plots (PCO). A morphological cladogram has been constructed using fifteen phenotypic taxonomic relevant characters. We have also developed an optimized Cystoseira sl DNA extraction protocol. We have tested it to obtain amplicons from mt23S, tRNA-Lys and psbA genes. With these sequence data, we have built a phylogenetic supertree avoiding threatened Cystoseira sl species. Cartography and distribution analysis show that the response to hydrodynamism predicts perennial or seasonal behaviors. Morphological cladogram detects inter-specifical variability between our species and reference studies. Our DNA phylogenetic tree supports actual classification, including for the first-time Treptacantha sauvageauana and Treptacantha algeriensis species. These data support a complex distribution and speciation of Cystoseira sl spp. in the Mediterranean, perhaps involving Atlantic clades. The high ecological value of our area of study merits a future protection status as a Special Conservation Area.
... All sites were gently sloping to sub-vertical rocky platforms, typically suitable for the growth of Cystoseira spp. (Lasinio et al. 2017), and covered a broad latitudinal gradient where C. compressa could be found (Mancuso et al. 2018). Cystoseria compressa is one of the most widespread habitat-forming species of Cystoseira in the Mediterranean Sea, able to colonize the rocky shore from the infralittoral (max 40 m depth) to the intertidal zone in both exposed and sheltered places (Gómez-Garreta et al. 2002). ...
... In the intertidal zone, C. compressa remains one of the relatively common Cystoseira spp. along the shallow Italian coasts, where its ecological status explained by cooccurring anthropogenic and environmental stressors (Mancuso et al. 2018). Knowing the physiological responses of C. compressa to ambient air and water temperatures is crucial to understand how this alga could cope with novel environmental conditions. ...
Article
Full-text available
Understanding the physiological responses of intertidal seaweeds to environmental factors is fundamental to characterize their local physiological adaptation and success in the face of climate change. We measured the photosynthetic activity and the total phenolic content of the intertidal alga Cystoseira compressa and explored their relationship with latitude or local ambient air and seawater temperatures. Our results show that, when submerged, the photosynthetic activity of C. compressa showed values typical for non-stressed thalli, and the seawater temperatures found across sites explained the variability of these values. We observed a decrease in the photosynthetic activity of C. compressa when exposed to air, compared to a submerged condition. This activity remained stationary up to 28 °C and then started to decrease with higher air temperatures. The total phenolic content of C. compressa at the end of low tide changed across the study sites from 0.12 to 0.53 % DW. Phenolic variability was explained by the long-term thermal water conditions experienced by the algae, rather than short-term variations encountered during tidal cycles. Overall, our results suggest a crucial role played by temperature in driving the physiological traits of the intertidal C. compressa.
... For instance, C. amentacea var. stricta, T. algeriensis and C. compressa, with large productive potential, require light saturation [57] and high hydrodynamism [13,27,31,37,58,59]. Consequently, they are frequently found in rifts and other exposed places. ...
... Cystoseira sl evolution data would generate time series that allows to know the state of these communities, evaluating the health of our coast. This type of study is already being carried out in different areas of Mediterranean Sea [20,31,59,77]. ...
Preprint
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Cystoseira is a relevant alga, which forms dense meadows on rocky substrates up to 100 meters deep. They are widely recognized as bioindicators for their restricted habitat (sub-coastal zone) and low tolerance to pollution. We have monitored Cystoseira sensu lato (sl) spp. in abrasion platforms in Cabo de Las Huertas (Alicante, SE Spain), a total of seven species. A cladogram has been constructed using fifteen phenotypic taxonomic relevant characters. We have also optimized Cystoseira DNA extraction and sequenced amplicons from mt23S, tRNA-Lys, and psbA genes of five Cystoseira sl species from Cabo de Las Huertas. Our phylogenetic supertree, built with these sequences, backs three clades in the genus. Rare species Treptacantha sauvageauana and Treptacantha algeriensis, sequenced for the first time, are included with T. elegans and the Atlantic species T. baccata and T. abies-marina in Cystoseira-VI or Cystoseira-II clades. Our data supports a complex colonization of Cystoseira (sl) spp. in the Mediterranean, perhaps involving Atlantic clades.
... For example, to explain differences in fucalean seaweed abundance and distribution, an understanding of the underlying ecological processes is necessary (Rindi and Guiry, 2004;Orfanidis et al., 2008), and therefore, quantification of their spatial patterns is needed (Wiens et al., 1993;Underwood, 1996;Benedetti-Cecchi et al., 2001;Fraschetti et al., 2005). Despite this interest in scale-specific patterns, effective implementation of multiscale approaches in theoretical and empirical research is still limited (Benedetti-Cecchi et al., 2001;Fraschetti et al., 2005;Mancuso et al., 2018). ...
... However, although the specific mechanisms behind these changes have not been fully understood yet, habitat destruction and decrease in water quality are likely to play a major role in the decline of perennial species (Tsiamis et al., 2013;Thibaut et al., 2015;Iveša et al., 2016;Rindi et al., 2020). These processes are indicators of nutrient enhancement, water turbidity, and high eutrophication levels, which are invoked in several studies as the main causes for the regression of fucalean species Mancuso et al., 2018) and seagrasses in the Mediterranean Sea. The input of nutrients and changes in water transparency are considered among the processes affecting the growth of macrophyte communities (De Jonge et al., 2002;Viaroli et al., 2008). ...
Article
Full-text available
Algal habitat-forming forests composed of fucalean brown seaweeds ( Cystoseira , Ericaria , and Gongolaria ) have severely declined along the Mediterranean coasts, endangering the maintenance of essential ecosystem services. Numerous factors determine the loss of these assemblages and operate at different spatial scales, which must be identified to plan conservation and restoration actions. To explore the critical stressors (natural and anthropogenic) that may cause habitat degradation, we investigated (a) the patterns of variability of fucalean forests in percentage cover (abundance) at three spatial scales (location, forest, transect) by visual estimates and or photographic sampling to identify relevant spatial scales of variation, (b) the correlation between semi-quantitative anthropogenic stressors, individually or cumulatively (MA-LUSI index), including natural stressors (confinement, sea urchin grazing), and percentage cover of functional groups (perennial, semi-perennial) at forest spatial scale. The results showed that impacts from mariculture and urbanization seem to be the main stressors affecting habitat-forming species. In particular, while mariculture, urbanization, and cumulative anthropogenic stress negatively correlated with the percentage cover of perennial fucalean species, the same stressors were positively correlated with the percentage cover of the semi-perennial Cystoseira compressa and C. compressa subsp. pustulata . Our results indicate that human impacts can determine spatial patterns in these fragmented and heterogeneous marine habitats, thus stressing the need of carefully considering scale-dependent ecological processes to support conservation and restoration.
... The Po discharges into the Adriatic large amounts of nutrients, sediments and pollutants, a large part of which is carried southwards by coastal currents. High levels of nutrients, especially if combined with high loads of sediments, are well known to be deleterious for benthic algae requiring high environmental quality; the best-known example is represented by fucalean brown algae (Strain et al. 2015;Mancuso et al. 2018), of which at least four species (Fucus virsoides, Cystoseira foeniculacea, Cystoseira humilis, Sargassum acinarium) disappeared from the Riviera. The reduction in species diversity of these seaweeds reflects their general decline throughout most of the Mediterranean (Cormaci and Furnari 1999;Benedetti-Cecchi et al. 2001;Thibaut et al. 2005Thibaut et al. , 2015, for which eutrophication and chemical pollution are generally considered key factors (Mancuso et al. 2018). ...
... High levels of nutrients, especially if combined with high loads of sediments, are well known to be deleterious for benthic algae requiring high environmental quality; the best-known example is represented by fucalean brown algae (Strain et al. 2015;Mancuso et al. 2018), of which at least four species (Fucus virsoides, Cystoseira foeniculacea, Cystoseira humilis, Sargassum acinarium) disappeared from the Riviera. The reduction in species diversity of these seaweeds reflects their general decline throughout most of the Mediterranean (Cormaci and Furnari 1999;Benedetti-Cecchi et al. 2001;Thibaut et al. 2005Thibaut et al. , 2015, for which eutrophication and chemical pollution are generally considered key factors (Mancuso et al. 2018). The loss of Fucus virsoides is especially remarkable, given the biogeographical significance of this species: it is a glacial relict endemic of the Adriatic Sea, whose current distribution is restricted to a few areas in the northern and central Adriatic (Orlando-Bonaca et al. 2013;Falace et al. 2018). ...
Article
Full-text available
Seaweed communities are important coastal ecosystems representing good indicators of environmental variation related to climate change and other long-term changes. Long-term variation in the distribution of seaweed communities and individual seaweed species has been intensively investigated; however, long-term studies considering the whole seaweed flora of a geographical area have been infrequently produced, despite of their potential to unravel major changes. The macroalgal flora of a coastal area subjected to urban influences (Conero Riviera, Mediterranean Sea) was investigated comparing the contemporary flora with historical data available for three periods (1941–1946; 1964–1976; 1997–1999). The most evident change was the disappearance of 25–30 species that were present in 1941–1946 (and, in some cases, still in 1964–1976). Such losses are not recent and took place mainly in the years 1940–1960. A general environmental deterioration due to the urbanization of the area of Ancona is suggested as main cause of their disappearance; there is no evidence that their loss was related to climate change. Another major change was the introduction of 9 nonindigenous species, which were probably introduced from the Lagoon of Venice by maritime traffic. One of them, Melanothamnus japonicus, is now very abundant on the Conero Riviera. The results show that present floristic patterns may result from changes that took place at the time scale of many decades, which are rarely considered in studies on benthic vegetation. We suggest that future floristic studies of benthic macroalgae should be based on large-scale programs of DNA barcoding, in order to avoid overlooking invasive cryptic species.
... and cyanobacteria characterized the impacted sites of Beirut and Tripoli. These results are in agreement with the general trend of fucoid loss and replacement by turf algae well described along Mediterranean coasts by several studies (Ballesteros et al., 2007;Mangialajo et al., 2008;Airoldi et al., 2014;Connell et al., 2014;Strain et al., 2014;Blanfuné et al., 2017;Mancuso et al., 2017;Badreddine et al., 2018;Orlando-Bonaca and Rotter, 2018). The comparison with the few existing historical data allowed highlighting that the loss of individuals of Dendropoma anguliferum in the Tyr region seems to have happened in a recent past, as the presence of living individuals (as Dendropoma petraeum) was reported in 2002 (Morhange et al., 2006). ...
... In the last 4 decades, the decline of Cystoseira sensu lato (henceforth referred to as Cystoseira) (Fucales, Phaeophyceae) forests in the Mediterranean Sea has been widely documented (e.g. Munda, 1980;Munda, 1982;Hoffman et al., 1988;Munda, 1993a;Cormaci & Furnari, 1999;Thibaut et al., 2005;Mangialajo, Chiantore & Cattaneo-Vietti, 2008;Thibaut et al., 2015a;Thibaut et al., 2015b;Blanfuné et al., 2016;Valdazo et al., 2017;Mancuso et al., 2018) and has been mainly attributed to the interplay of several human impacts on the coastal environment, such as habitat destruction, pollution and overgrazing by sea urchins and herbivorous fish (e.g. Bellan-Santini, 1966;Arnoux & Bellan-Santini, 1972;Munda, 1974;Munda, 1982;Verlaque, 1987;Hoffman et al., 1988;Munda, 1993b;Chryssovergis & Panayotidis, 1995;Cormaci & Furnari, 1999;Benedetti-Cecchi et al., 2001;Soltan et al., 2001;Hereu, 2004;Sales & Ballesteros, 2009;Sales et al., 2011;Gianni et al., 2013;Pinedo, Zabala & Ballesteros, 2013;Strain et al., 2014). ...
Article
Abstract 1. The worldwide decline of marine forests, due to human impacts and climate change, emphasizes the need to develop and implement effective and sustainable solutions to restore these endangered habitats and to re-establish the services they provide. 2. In this study, the ex situ restoration of Treptacantha barbata, a Mediterranean subtidal habitat-forming species of brown seaweed, was for the first time implemented in a marine protected area in the Adriatic Sea. Two restoration efforts were performed in 2019. The first one was started in winter, after a marine heatwave that triggered early fertility, the second one in spring, when the species usually reproduces. 3. This study aimed to evaluate: 1) the disruptive effects of a thermal anomaly on the reproductive biology and performance in culture of T. barbata; and 2) the impact of the grazing pressure on juveniles after the outplanting. 4. The first cultivation was more productive than the second one, in terms of zygote release and germling growth. To mitigate the low efficiency of the second culture and to avoid prolonged highly-demanding maintenance in the mesocosms, the cultivation period was extended outdoors using a structure suspended in the water column. 5. The modular frames conceived for outplanting T. barbata proved to be effective because of their easy operability and low cost. Controlling for herbivorous fish had significant positive effects on both juvenile survival and growth. 6. The outcomes highlighted that an unpredictable climatic event and fish grazing were major threats that impaired the restoration process of T. barbata. These stressors should be considered when developing plans to implement effective large-scale restoration of canopy-forming macroalgae.
... Local drivers acting at the degraded location could explain the sharp differences found between locations. However, the specific causes driving a community shift in urban areas are still an open issue (Benedetti-Cecchi et al. 2001, Bertocci et al. 2017, Mancuso et al. 2018 and are far beyond the scope of this study. Even so, the correlation between urbanization and the replacement of fucoid algae and other phaeophycean groups by E. elongata is well known in the Mediterranean Sea , Mangialajo et al. 2008, Pinedo and Ballesteros 2019, pointing to eutrophication and sedimentation among the most essential drivers of change in anthropogenic-affected habitats (Munda 1993, Airoldi 2003. ...
Article
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The seaweed Caulerpa cylindracea Sonder is one of the most important invaders on Mediterranean rocky shores. However, many driving pressures affecting its spread are poorly understood and seem to involve the interactions between abiotic and biotic factors. We studied the invasiveness of C. Cylindracea on two shallow vermetid platforms with a con­trasting ecological status on which C. Cylindracea was first detected simultaneously 15 years ago. The cover values of C. Cylindracea and the other macroalgal species were assessed for one year, embracing the whole platform width. Caulerpa cylindracea cover was higher on the platform that had a low ecological status, especially during warmer months at the outer seaward margin. The ecological status of the overstory of native species seems to be a key point conditioning the success of C. Cylindracea invasiveness on these platforms.
... Several studies conducted in the Mediterranean have reported on the past and the present distribution and abundance of Cystoseria canopies (Thibaut et al., 2014;Mancuso et al., 2018), detecting regressions or losses caused by the above mentioned factors (Cormaci & Furnari, 1999;Thibaut et al., 2005;Falace et al., 2010;De La Fuente et al., 2018). Their natural recovery, in the absence of adults, is hampered by the very limited dispersal of Cystoseira species due to the rapid fertilization of their large eggs and zygote sinking (Falace et al., 2018). ...
Article
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In the Mediterranean Sea, brown algae belonging to the Cystoseira genus play a valuable role as foundation species. Due to evidences of regression/loss of the habitats of these species caused by the interplay of human and climatic disturbances, active restoration measures have been encouraged by EU regulations. In particular, nondestructive restoration techniques, which avoid the depletion of threatened species in donor populations, are strongly recommended. In the framework of the EU project ROCPOP-Life, the first ex situ outplanting experience of Cystoseira amentacea var. stricta has been implemented in the Cinque Terre Marine Protected Area (northwestern Mediterranean). A total of 400 clay tiles, hosting approximately three mm-long germlings of C. amentacea, were fixed to the rocky shore with screws: the tiles were monitored for the next 2 months by photographic sampling, and survival (presence/absence of juveniles on the tiles), cover and growth were assessed. Additional sampling was performed 6 months after tile deployment, after which an unprecedented storm surge severely affected the restoration performance. After 2 months, over 40% of the tiles were covered with Cystoseira juveniles, which reached approximately eight mm in total length. The tiles that survived the storm hosted three to six cm-long juveniles. The high cover (≥25%), assuring moisture and shading, and the appropriate size of the juveniles, to avert micro-grazing, at time of deployment were key to the survival and growth of the outplanted juveniles, increasing the potential for restoration success. Our findings show that outplanting of midlittoral canopy-forming species is a feasible approach for restoration efforts, with particular attention given to the early phases: (i) laboratory culture, (ii) transport, and (iii) juvenile densities. These results are strongly encouraging for the implementation of restoration actions for C. amentacea on a large scale, in light of EU guidelines.
... Both human impacts and climate stressors are severely hampering these ecosystems, causing regression or, in some cases, even local extinction of Cystoseira species in the Mediterranean Sea (Mangialajo et al. 2008;Irving et al. 2009;Sales and Ballesteros 2009;Sales et al. 2011;Thibaut et al. 2015;Mancuso et al. 2018;Bevilacqua et al. 2019). Owing to their great ecological value and their endangered status, all the Cystoseira s.l. ...
Article
Carpodesmia barbatula (= Cystoseira barbatula) (Fucales, Phaeophyta) is a species endemic to the Southern Mediterranean Sea, which grows in clean waters on exposed sublittoral rocky shores. Together with other species of the genus Cystoseira sensu lato, it is an ecosystem engineer that forms dense canopy forests, sustaining biodiversity, productivity and nutrient cycling in temperate rocky reefs. Human impacts and climate stressors are seriously hampering these ecosystems and actual conservation efforts appear insufficient for their preservation. Restoration actions could be a solution for the loss of these habitats, but they require the deep knowledge of the target species. In the present study, we describe egg release, zygote development and germling growth of C. barbatula, poorly known, despite its importance in the upper sublittoral seaweed flora. The aim is to improve the knowledge on the early life stages of this rare and threatened species, towards its possible future restoration.
... Decline or loss of Cystoseira populations sensu lato has been reported from many rocky coasts particularly close to urban areas due to combined effects of anthropogenic impacts and climate-change (Benedetti-Cecchi et al., 2001;Thibaut et al., 2005;Arevalo et al., 2007;Mangialajo et al., 2008;Strain et al., 2014;Mineur et al., 2015;Mancuso et al., 2018;Blanfuné et al., 2019). In this context, the introduction of invasive seaweeds may add further stress on these vulnerable habitats facilitating their shift towards less diverse and less structured assemblages (Navarro-Barranco et al., 2018). ...
Article
Invasive seaweeds threaten biodiversity and socio-economics values of worldwide marine ecosystems. Understanding to what extent invasive seaweeds can modify local biodiversity is one of the main priorities in conservation ecology. We compared the molluscan assemblage of the invasive Asparagopsis taxiformis with that of the native Ericaria brachycarpa and explore if variation in the molluscan assemblage diversity was related to the substrate attributes (biomass, and thallus, canopy, and interstitial volumes) of the algae. Results showed that A. taxiformis harboured lower diversity and trophic structure of the molluscan assemblage compared to E. brachycarpa. Biomass was the variable that better explained the variation of abundance and number of species as well as the multivariate structure of the molluscan assemblage. Overall, our results suggest that a complete habitat shift from native to invasive species can potentially trigger bottom-up effects in rocky shores habitats, reducing the biodiversity and the services provided by the invaded habitat.
... Cystoseira species are long-living and their status can be used to estimate the possible onset of disturbance and degradation (Giaccone & Bruni, 1973;Ballesteros et al., 2007;Sales & Ballesteros, 2009;Mancuso et al., 2018). They are particularly prone to both natural and anthropogenic environmental changes, including temperature rise and heatwave events, extremes of weather and marine phenomena, and introduction of non-indigenous species. ...
... Consequently, they may be substituted by less structured and opportunistic species, such as turf-forming filamentous seaweeds, mussels or sea urchin-driven barrens. This shift may lead not only to an overall simplification of the architectural complexity of the dominant biological habitat, but also to the loss of their associated epibenthic diversity (Benedetti-Cecchi et al. 2001;Micheli et al. 2005;Thibaut et al. 2005Thibaut et al. , 2015Mangialajo et al. 2008;Perkol-Finkel and Airoldi 2010;Sala et al. 2012;Buia et al. 2013;Grech et al. 2015;Mancuso et al. 2018). ...
Article
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Brown macroalgae belonging to the genus Cystoseira (Fucales: Sargassaceae) are canopy-forming organisms whose recent decline at basin and local scale has been widely documented. We hereby characterized the molluscan assemblages associated with three Cystoseira taxa (C. amentacea, C. compressa, and C. crinita) from Ischia Island (Italy, Tyrrhenian Sea), and tested whether different congeneric taxa may syntopically support a different biota. In particular, these assemblages were compared among three Cystoseira species, two times of sampling, and six sites in terms of multivariate structure, as well as for synthetic measures of diversity, including the total richness of taxa, the exponential Shannon index, and the reciprocal Simpson index. A total of 24736 molluscan individuals were collected, overall belonging to 52 taxa. The majority of the identified species included micrograzers and filter feeders in agreement with similar previous studies. The composition of associated molluscan assemblages, which was mainly represented by juvenile individuals, differed among the three Cystoseira species, suggesting that even congeneric taxa do not support an analogous benthic fauna. The present findings shed light on the molluscan biota associated with Cystoseira taxa in the Gulf of Naples and strengthen the importance of such habitat-forming macroalgae in structuring the local infralittoral invertebrate biodiversity and as a nursery for species-specific associated molluscs.
... Cystoseira species are long-living and their status can be used to estimate the possible onset of disturbance and degradation (Giaccone & Bruni, 1973;Ballesteros et al., 2007;Sales & Ballesteros, 2009;Mancuso et al., 2018). They are particularly prone to both natural and anthropogenic environmental changes, including temperature rise and heatwave events, extremes of weather and marine phenomena, and introduction of non-indigenous species. ...
Article
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The status of the “Biocoenosis of the Infralittoral Algae” of the upper infralittoral zone (at 5 m depth) from two selected stations along the eastern coast of Sicily (Ionian Sea, Mediterranean) was studied with a multiproxy approach involving the study of algae and associated protist and animal organisms, including foraminifers, serpulids, molluscs, bryozoans and ostracods. Scraped samples (40x40 cm) were collected at selected seasons during a 2-year period (2015-2016) in order to identify possible seasonal and spatial differences between the two stations, and to compare present data with historical ones. A community made up of the algae Halopteris scoparia, Padina pavonica, Dictyota dichotoma, Ellisolandia elongata and several other geniculate coralline algae was found in sites historically colonised by a Cystoseira brachycarpa community, which was not found during our study. These algae presently structure the community and provide substratum for several associated epibiotic species. Hierarchical cluster analysis and Non-Metric Multi-Dimensional Scaling Ordination significantly differentiate the communities between the two stations but show no clear seasonal trend. Differences largely relate to changes in the algal vegetation and the impact produced by the regression of structuring species on epibiots (especially serpulids and bryozoans). Comparison with historical algal data from the area indicates the disappearance of Cystoseira brachycarpa, which was present at least until the last ’1990s, and a community degradation with a considerable loss in species richness. This parallels observations in other Mediterranean areas, and could be related to the increase in echinoid population density and their heavy grazing activity.
... Fortnightly snorkeling surveys were also conducted to monitor the status of the algae. Image analysis was performed by CoralNet (Beijbom et al., 2012 to extrapolate the cover percentage of C. rayssiae and other macro-species (Mancuso et al., 2018). The same forest (Fig.1) was investigated in October 2017 (fall) and April 2018 (spring) with benthic incubation chambers to measure community metabolic rates (Peleg, 2016). ...
Conference Paper
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The SE Levantine Basin is the hottest, fastest warming and most alien-invaded corner of the Mediterranean Sea. These characteristics make this region a natural laboratory to test the effects of climate change and bioinvasion pressures on benthic communities. Along the Israeli Mediterranean Sea coast, an endemic species of the genus Cystoseira, C. rayssiae, was first described by Ramon in 2000. Since then little has been done to study its ecology. This is in contrast to the Western Mediterranean, where many Cystoseira species, known to be important habitat formers, have been studied extensively and are listed in the Annex I of the Conventions of Bern and Barcelona because of many anthropogenic threats. The lack of knowledge on C. rayssiae ecology in the SE Levantine Basin prevents the development of protection measures for this high risk species. This study presents results on the annual dynamics of C. rayssiae in the Haifa region in terms of growth, reef cover, biomass and metabolic ecosystem functions (associated species, oxygen production and carbon budget). Our results show that its branched form only appears in winter and spring when it provides habitat for multiple species (two-fold higher associated taxa richness compared to turf), high oxygen production (12 mmol O2/m2/h) and high capacity for C sequestration (-12 mmol C/m2/h) compared to turf and alien dominated macrophyte communities. During the warmer months (July-November) it becomes branchless and dormant with lower habitat provisioning capacity, metabolism and a three-fold decrease in length from May to August, from the peak season to the dormant phase. These data suggest that the expected fast warming in the Levant basin may pose a considerable threat to this important habitat forming species and to the whole reef metabolism, with a possible replacement by similar non-indigenous, thermophilic macroalgae.
... and cyanobacteria characterized the impacted sites of Beirut and Tripoli. These results are in agreement with the general trend of fucoid loss and replacement by turf algae well described along Mediterranean coasts by several studies (Ballesteros et al., 2007;Mangialajo et al., 2008;Airoldi et al., 2014;Connell et al., 2014;Strain et al., 2014;Blanfuné et al., 2017;Mancuso et al., 2017;Badreddine et al., 2018;Orlando-Bonaca and Rotter, 2018). The comparison with the few existing historical data allowed highlighting that the loss of individuals of Dendropoma anguliferum in the Tyr region seems to have happened in a recent past, as the presence of living individuals (as Dendropoma petraeum) was reported in 2002 (Morhange et al., 2006). ...
... Все указанные виды Cystoseira sensu lato являются доминантами одноименных ассоциаций на глубинах от 0.5 до 10-15 м и глубже [26,27,39]. При этом в последние десятилетия в Средиземном море из-за потепления и антропогенного влияния цистозиры становятся более редкими видами, а их исчезновение сопровождается существенным снижением видового разнообразия ценозов [23,32,41,46,47]. Основными сопутствующими видами, которые способны заселять освободившиеся ниши и формировать новые сообщества, там являются Padina pavonica, Dictyota dichotoma, Ellisolandia elongata и Halopteris scoparia [23], т.е. ...
Article
На базе полевых наблюдений макрофитобентоса п-ва Абрау Черного моря исследовано влияние двух наиболее распространенных видов бурых водорослей Черного моря Cystoseira bosphorica и Treptacantha barbata (Cystoseira sensu lato) на видовое богатство и биомассу фитоценозов, а также биомассу и встречаемость сопутствующих видов макроводорослей. В ценозах цистозир обнаружено 48 видов макроводорослей, в том числе 27 видов красных (Rhodophyta), 11 – бурых (Ochrophyta, Phaeophyceae) и 10 – зеленых (Chlorophyta). Показано, что снижение биомассы цистозир в 2–4 раза не оказывает существенного влияния на видовое богатство ценозов, однако приводит к снижению их общей биомассы и разнонаправленному изменению биомассы и встречаемости многих видов макроводорослей. Реакция ценозов на снижение биомассы C. bosphorica и T. barbata, а также ее негативный характер – снижение продуктивности и видового богатства – сильнее проявляются на больших глубинах.
... Since the beginning of the 20 th century, a large number of studies have been conducted on macrophyte communities that focused mostly on the Western Mediterranean basin (Serio et al., 2006;Mangialajo et al., 2008a;Ballesteros et al., 2009;Cormaci et al., 2012;Tasķin et al., 2012;Vergeś et al., 2014;Thibaut et al., 2015;Mineur et al., 2015;Ivesǎ et al., 2016;Mancuso et al., 2018;Valdazo et al., 2020;Medrano et al., 2020;Orlando-bonaca et al., 2021). In contrast, information on distribution, dynamics, and ecology of these forests in the Eastern basin and specifically in the Levantine Sea, is scarce. ...
Article
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Ocean warming is a major threat to marine ecosystems, especially to species with a narrow thermal niche width and narrow biogeographic distribution, like some habitat-forming seaweeds. Declines of marine forests have been reported for several canopy-forming species in temperate regions, including the Mediterranean Sea, where they are dominated by species from the order Fucales, but most of the information on their ecology and status comes from the western basin. Here, we studied the thermal vulnerability and metabolic functioning of the endemic Gongolaria rayssiae located in fast-warming waters of the Israeli Mediterranean coast. We followed seasonal changes in phenology and ecology of G. rayssiae and its associated community during 2018-2020. Its highest biomass, density and thallus length were documented in spring-early summer (March-mid June). When seawater temperature exceeded 25°C, it shed its branches until February, when re-growth normally occurred. The thermal performance curve of G. rayssiae was determined by exposing it to 11 temperature levels in the range 15-35°C. The thermal optimum temperature for gross oxygen production, determined from the fitted curve, was 24.5°C. This relatively low thermal optimum suggests marked sensitivity to warming and supports the notion that G. rayssiae is a temperate relict species in the area. Additionally, we conducted seasonal ex-situ incubations during daytime and nighttime and recorded the highest primary productivity in spring, when it is at its peak of growth. In this season, its net inorganic carbon uptake was 42 ± 11 µmol C g dw-1 h-1 ( ± SD), while in its branchless form during late summer, it decreased six-fold. Due to the fast ocean warming conditions of the area, we hypothesize that the growth season of the species will shrink, and the species may eventually disappear. Finally, when exposed to high temperatures in natural and manipulative conditions, G. rayssiae exhibited a dramatic decline in its carbon sequestration rates with important implication for the carbon budget of the reef. This study highlights the importance of establishing a species phenology and environmental sensitivity (and especially that of endemic ones) in rapidly warming ecosystems, to estimate its potential fate due to climate change.
... La maggior parte delle specie appartenenti al genere Cystoseira (con l'eccezione di Cystoseira compressa, considerata più tollerante) è sensibile ad un ampio spettro di stress ambientali, legati in particolare all'eutrofizzazione, alla presenza di agenti inquinanti di origine urbana, agricola e industriale, all'aumento della torbidità dell'acqua, ai cambiamenti climatici , Thibaut, 2014Mancuso et al., 2018). ...
... Due to their high vulnerability to natural and human disturbance (Mancuso et al. 2018;Orfanidis et al. 2021;Sales and Ballesteros 2009), Cystoseira s.l. species serve as indicators of Good Environmental Status in European (i.e., Marine Strategy Framework Directive 2008/56/EC, Water Framework Directive 2000/60/EC), and National Monitoring Programs. ...
Article
The loss of Mediterranean macroalgal populations dominated by Cystoseira sensu lato is driven by a multitude of pressures. In the eastern Mediterranean Sea, climate change and the establishment of Lessepsian herbivore species have further intensified the ongoing decline of these canopy-forming algae. Knowledge of the reproductive phenology, embryology and growth of Cystoseira species is the first step towards successful reforestation measures. Gongolaria montagnei is one of the most common canopy-forming algal species with a wide horizontal and vertical distribution along the Greek coasts. Mature receptacles were collected from Saronikos Gulf (Aegean Sea), and germlings were cultured in mesocosms for 34 days, reaching up to 1.30 mm in length. Divisions and early developmental stages of G. montagnei are described and possible implications for future restoration efforts are discussed. A new approach to growth rate modeling, based on surface measurements of embryos and germlings is presented.
... Differently from Bianchi et al. (2018) we found that two other large brown seaweeds, Cystoseira compressa and Dictyopteris polypodioides, are still generally common on the island, although with distribution concentrated in certain habitats and certain parts of the shoreline (Table 1). These are two widespread Mediterranean phaeophytes that thrive in a wide range of environmental conditions and may also occur at sites moderately affected by anthropogenic disturbances (Mangialajo et al. 2008;Mancuso et al. 2018;Orfanidis et al. 2021). We also confirm the presence of Gongolaria elegans in the rockpool on the SE shore, where this species was previously recorded by Mangialajo (2007). ...
Article
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Gallinara Island, a small island located 1.5 km off the shore of Liguria (Italy, north-western Mediterranean Sea) was included in a list of proposed Marine Protected Areas (MPA) in the early 90s. Since then, its benthic assemblages have been studied in detail and the main macrophytic communities have been mapped. A detailed assessment of its benthic macroalgal flora, however, has never been made. Gallinara was visited in the course of 5 consecutive years and its macroalgal flora was studied based on collections made by snorkelling and SCUBA diving. Overall, 141 macroalgal taxa were collected and identified (23 Chlorophyta, 94 Rhodophyta, 24 Ochrophyta); 91 of them represent new records for the island. One of the most notable new records is the non-indigenous red alga Womersleyella setacea , previously unreported from the island and widely distributed, particularly on the south-eastern shore. Observations made in the course of the surveys confirm the rarefaction of some large-sized brown algae (particularly Sargassum vulgare ) but indicate also that others previously reported as rare ( Cystoseira compressa , Dictyopteris polypodioides ) are still common on the island.
... Eutrophication represents a threat to fishes and marine life in general. It changes biological communities, degrading fish habitats, such as sea grass meadows [109,110] or Cystoseira forests [111], and can be manifested even by anoxia that can cause almost total mortality of marine organisms in the community [112]. Coastal development degrades and alters coastal and shallow sea habitats. ...
Article
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The paper presents an analysis of biogeographic and habitat distribution patterns, and the conservation status data of Adriatic fishes, based on the last published checklist and evidence-based critical analyses of species presence. The total number of species recorded in the Adriatic is 449. The Adriatic has 58.8% of Mediterranean species richness, 76.1% of its families, and 87.8% of its orders. Among species discovered in the Adriatic after 2010, twelve species were attributed to biological invasion, mostly Atlantic immigrants or alien species, and ten species were attributed to improved research on the native ichthyofauna of the Adriatic area. About 58% of species are native species of Atlanto-Mediterranean origin, 21% are native species of wider global occurrence, 15% are Mediterranean or Mediterranean and Black Sea endemics and 5% originated outside Mediterranean Sea. The majority of species inhabit the benthic environment (71.9%), while others occur in the pelagic environment (20.7%) or are euryhaline (7.3%). The benthic littoral species are the most numerous Adriatic fishes, representing 40% of all species richness, whereas pelagic fishes are mainly eurybathic or epipelagic; only 3.6% of species are deep pelagic species. A Red Book of marine fishes of the Adriatic Sea is urgently needed to assess their conservation status, covering the entire Adriatic Sea and reviewing all fish species to assess their conservation status.
... Since the 2000s, brown algal forests have been perceived as habitats threatened by humans: researchers investigated patterns of local extinction (Curiel et al., 2001;Catra et al., 2006;Serio et al., 2006) and the major drivers of decline (e.g., urbanization, Benedetti-Cecchi et al., 2001;Mangialajo et al., 2008;human trampling, Milazzo et al., 2002human trampling, Milazzo et al., , 2004climate change, Schiaparelli et al., 2007;water pollution, Drago et al., 2004). In the last decade, efforts concentrated on investigating global and local drivers of forests decline (e.g., Porzio et al., 2011;Baggini, 2014;Mancuso, 2016;Buosi and Sfriso, 2017;Mancuso et al., 2018), among which overgrazing by herbivores emerged as a relevant threat (e.g., Agnetta et al., 2015;Gianni, 2016;Ferrario et al., 2016;Piazzi and Ceccherelli, 2019;Tamburello et al., 2019). ...
Article
Habitat degradation and loss are severely affecting macroalgal forests worldwide, and their successful mitigation depends on the identification of the drivers of loss and the implementation of effective conservation and restoration actions. We made an extensive literature review 1- to document the historical (1789–1999) and recent (2000−2020) occurrence of the genus Cystoseira, Ericaria and Gongolaria reported in the literature along the 8000 km of the coasts of Italy, 2- to assess their decline and patterns of extinction, 3- to ascertain the drivers responsible for these changes, 4- to highlight the existence of success stories in their conservation and natural recovery. In the last twenty years, overall information on the distribution of Cystoseira s.l. exponentially increased, although research focused almost exclusively on intertidal reefs. Despite the lack of systematic monitoring programs, the local extinction of 371 populations of 19 different species of Cystoseira s.l. was documented across several regions, since 2000. Coastal engineering and poor quality of waters due to urban, agricultural or industrial activities were often documented as leading causes of habitat loss. However, the drivers of extinction were actually unknown for the majority of the populations and cause-effects relationships are scarcely documented. Although the proportion of protected populations increased to 77.8%, Marine Protected Areas are unlikely to guarantee adequate conservation efficacy, possibly also for the widespread lack of management and monitoring plans dealing specifically with Cystoseira s.l. species, and few evidences of natural recovery were observed. Our review shows the dramatic lack of baseline information for macroalgal forests, highlighting the urgent need for the monitoring of less accessible habitats, the collection of long-term data to unveil drivers of loss, and an updated reporting about the conservation status of the species of interest to plan future interventions.
... In the last 4 decades, the decline of Cystoseira sensu lato (henceforth referred to as Cystoseira) (Fucales, Phaeophyceae) forests in the Mediterranean Sea has been widely documented (e.g. Munda, 1980;Munda, 1982;Hoffman et al., 1988;Munda, 1993a;Cormaci & Furnari, 1999;Thibaut et al., 2005;Mangialajo, Chiantore & Cattaneo-Vietti, 2008;Thibaut et al., 2015a;Thibaut et al., 2015b;Blanfuné et al., 2016;Valdazo et al., 2017;Mancuso et al., 2018) and has been mainly attributed to the interplay of several human impacts on the coastal environment, such as habitat destruction, pollution and overgrazing by sea urchins and herbivorous fish (e.g. Bellan-Santini, 1966;Arnoux & Bellan-Santini, 1972;Munda, 1974;Munda, 1982;Verlaque, 1987;Hoffman et al., 1988;Munda, 1993b;Chryssovergis & Panayotidis, 1995;Cormaci & Furnari, 1999;Benedetti-Cecchi et al., 2001;Soltan et al., 2001;Hereu, 2004;Sales & Ballesteros, 2009;Sales et al., 2011;Gianni et al., 2013;Pinedo, Zabala & Ballesteros, 2013;Strain et al., 2014). ...
... In coastal environments, benthic organisms from rocky shore habitats, such as macroalgae, are commonly used as indicators of water quality based on a range of descriptors, including the cover of certain species, total species richness and taxa composition (D'Archino and Piazzi, 2021). In some cases, these descriptors were examined in terms of spatial patterns and related to environmental variables considered as proxies of water quality (e.g., Arévalo et al., 2007;Mancuso et al., 2018;Pinedo et al., 2007;Zubia et al., 2018). In other situations, different descriptors were included in the calculation of multimetric indices for comparing sites of interest with reference sites (e.g. ...
Article
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Ecological indices are useful tools for environmental managers to monitor and detect changes caused by natural or anthropogenic disturbances. Despite the fact that descriptors of Fucales species are often included in indices for evaluating changes in coastal marine habitats, there is no index based solely on Fucales abundance. This study proposes the Fucales Index (FI), based on four classes of abundance of a selected Fucales species. The ability of FI to detect changes in the abundance of Sargassum sp. was tested in a Brazilian bay that is subjected to the effluent plume from a nuclear power plant. FI was significantly different when comparing areas inside and outside of the plume area, and it increased with increasing distance from the source of the disturbance. These findings suggest that FI is a suitable tool for assessing the effect of an effluent plume and potentially of other disturbances on rocky shores hosting Fucales.
... In the Mediterranean Sea, vermetid reefs represent a unique and highly diverse biogenic construction structurally comparable to coral reefs in tropical areas (Safriel and Ben-Eliahu, 1991). They are largely colonized by one of the most productive and valuable macroalgal forests, formed by the canopy-forming brown macroalgae belonging to the Order Fucales Ericaria amentacea (=Cystoseira amentacea) and Cystoseira compressa; Mancuso et al., 2018). When present, this canopy-forming brown macroalga increases the local three-dimensional complexity and spatial heterogeneity, providing food, shelter, and nurseries to many associated species, thereby enhancing local biodiversity and productivity (Ballesteros et al., 1998;Cheminée et al., 2013;Gianni et al., 2013;Gorman et al., 2013;Piazzi et al., 2018). ...
Article
Biodiversity plays a key role for our planet by buffering ongoing and future changes in environmental conditions. We tested if canopy-forming algae enhancing biodiversity (CEB) in a Mediterranean intertidal reef ecological community could alleviate the effect of stressors (heat waves and pollution from sewage) on community metabolic rates (as expressed by oxygen consumption) used as a proxy of community functioning. CEB exerted a buffering effect related to the properties of stressor: physical-pulsing (heat wave) and chronic-trophic (sewage). After a simulated heat wave, CEB was effective in buffering the impacts of detrimental temperatures on the functioning of the community. In reefs exposed to chronic sewage effluents, benefits derived from CEB were less evident, which is likely due to the stressor's contextual action. The results support the hypothesis that ecological responses depend on stressor typology acting at local level and provide insights for improving management measures to mitigate anthropogenic disturbance.
... waves, currents and nutrient concentrations) deserve further attention as they might also play an important role, particularly at local scales (e.g. Mabin et al., 2019;Mancuso et al., 2018;Piñeiro-Corbeira et al., 2019;Robuchon et al., 2017;Smale & Wernberg, 2013;Straub et al., 2019). ...
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Aim To understand spatial‐temporal changes (beta‐diversity) in coastal communities and their drivers in the context of climate change. Coastal ecosystems are extremely exposed and dynamic, where changes in seaweed assemblages have been associated with changing water temperatures. However, at local scale, the effects of changes in the upwelling events and related stressors seek further exploration. Location Galicia rías, North West of the Iberian Peninsula. Methods Using data collected in 42 sampling localities in Galicia rias and over two time periods (1998 and 2014), we analysed changes in the seaweed community's composition through time and space. We calculated the temporal beta‐diversity index and spatial beta‐diversity as the pairwise composition differences between sampling localities. We use generalized dissimilarity models, to identify local environmental drivers of spatial and temporal beta‐diversity. Results We found a significant change in seaweed communities of Galicia rias, between 1998 and 2014 (temporal beta‐diversity). They were mostly related to species loss rather than to species replacement. The dissimilarity among localities (spatial beta‐diversity) was significantly higher in 2014 than in 1998. Nitrate concentration was consistently predicted as the main driver of both temporal and spatial beta‐diversity patterns. Main conclusions Unlike other studies in marine ecosystems, our results suggest that observed changes in the structure of perennial seaweed assemblages in Galicia Rias might lead to a local biotic heterogenization, indirectly linked to climate change through changes in nutrients availability and the upwelling intensity. Changes in Galicia seaweed communities call scientific attention to the importance of local stressors in climate change studies.
... Néanmoins, un manque important ou une absence de données scientifiques sur la distribution des Laminariales en Méditerranée (Bartsch et al., 2008 ;Araújo et al., 2016) limitent l'appréciation de leur état actuel de conservation. En revanche, la situation des Fucales est bien connue : les données actuelles font part d'une régression généralisée de la richesse spécifique et de l'abondance des populations sur le pourtour du bassin méditerranéen occidental (Thibaut et al., 2005 ;Thibaut et al., 2015 ;Blanfuné et al., 2016 ;Mancuso et al, 2018). Cependant, des signes de résiliences (Iveša et al., 2016 ;Blanfuné et al., 2019), voire de stabilité sont perçus chez certaines espèces lorsque les ~ 14 ~ mesures de conservation sont effectives dans les aires marines protégées (Thibaut et al., 2016a). ...
Thesis
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Marine forests of brown algae (Phaeophyceae) are impacted by a combination of anthropic pressures. The fate of these ecosystems will depend on the adaptive abilities of populations facing this changing environment. Through my PhD, I studied the factors likely to control the genetic diversity of marine forests by focusing on two endemic species of the mediterranean basin, the Fucoid Ericaria zosteroides and the deep-sea kelp Laminaria rodriguezii. In the first part, I studied the connectivity of populations by a method of reduced representation sequencing of genomes (RAD-seq). The analysis of the genetic structure indicates a reduced connectivity for both E. zosteroides and L. rodriguezii populations. By coupling genetic structure and modeling of marine currents, I studied the role of propagules dispersal, taking as a study case, the populations of E. zosteroides in Provence. The results indicate that the genetic structure is predicted by ocean currents rather than spatial isolation. In the second part, I studied the mode of reproduction of the kelp L. rodriguezii, this species being one of the few of the genus Laminaria to reproduce by vegetative and sexual reproduction. The results obtained indicate an impact of clonality on the genomic diversity of L. rodriguezii, with contrasting levels depending on the populations. In addition to the fundamental questions raised by these results, the existence of a strong genetic structure at short distances for populations divided into habitat patches has important implications for the conservation of these species.
... The Mediterranean Sea is a warm temperate sea where kelps (Laminariales, Tylopteridales) are scarce, but species of the order Fucales are abundant in diversity and coverage in subtidal habitats Feldmann, 1937;Giaccone & Bruni, 1973;Gianni et al., 2013;Rodríguez-Prieto et al., 2013). In spite of their importance as ecosystem engineers and the regression of most of their populations (Bianchi et al., 2014;Cormaci & Furnari, 1999;Mancuso et al., 2018;Thibaut et al., 2005Thibaut et al., , 2015Thibaut et al., , 2016, and the emerging efforts to restore lost populations (De la Fuente et al., 2019;Gianni et al., 2020;Medrano et al., 2020;Verdura et al., 2018), there are still few ecophysiological studies dealing with their growth responses to different relevant environmental parameters such as light (Baghdadli et al., 1990;Delgado et al., 1995;Sant & Ballesteros, 2021a, 2021bTremblin et al., 1986), nutrients (Celis-Plá, Martínez, et al., 2014;Delgado et al., 1994), temperature (Baghdadli et al., 1990;Celis-Plá et al., 2017;Tremblin et al., 1986;Verdura et al., 2021), desiccation (Delgado et al., 1995) or salinity (Baghdadli et al., 1990;Celis-Plá et al., 2016;Tremblin et al., 1986) concentrated in a few, usually shallow water species. ...
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... Fucales are the most utilized biological quality elements and several population parameters (i.e. frond density, frond length frond-length/total frond-length ratio and taxonomic richness of epibionts) are considered valuable indicators of the ecological status of coastal waters (Wallenstein et al., 2013;de Casamajor et al., 2019;Mancuso et al., 2018). ...
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... La maggior parte delle specie appartenenti al genere Cystoseira (con l'eccezione di Cystoseira compressa, considerata più tollerante) è sensibile ad un ampio spettro di stress ambientali, legati in particolare all'eutrofizzazione, alla presenza di agenti inquinanti di origine urbana, agricola e industriale, all'aumento della torbidità dell'acqua, ai cambiamenti climatici , Thibaut, 2014Mancuso et al., 2018). ...
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We performed a study on the specific composition, structure, and dynamics of two Cystoseira mediterranea communities from the north-western Mediterranean submitted to different degrees of pollution. The structural complexity (species richness, specific distribution, and species and pattern diversity) and biomass production were lower in the polluted site. In this station, opportunistic algae (mainly UIva rigida) bloomed, and Mesophyllum lichenoides and some encrusting brown algae increased their cover. Other species (Jania rubens, and some Ceramiales) decreased their abundance when compared with the polluted site.
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Seaweed morphology is often shaped by the hydrodynamic environment. However, exposure to air at low tide represents an additional factor potentially affecting the morphology of intertidal species. Here we examined the relationships between the morphology of Hormosira banksii (Turner) Decaisne, an important intertidal habitat-forming seaweed in southern Australia, and environmental factors across multiple spatial scales around the island of Tasmania, Australia. Tasmania is surrounded by a diverse coastline with differences in wave exposure, tidal parameters and temperature. We sampled Hormosira from four regions (100's km apart), three sites (10's km apart) within each region and two zones (metres apart; eulittoral and sublittoral) at each site and measured multiple morphological variables to test for differences in morphology at those different spatial scales. Thirteen environmental variables reflecting wave exposure, tidal conditions and temperature for each site were generated to assess the relationship between Hormosira morphology and environmental variation. Morphology varied at all spatial scales examined. Most notably, north coast individuals had a distinct morphology, generally having smaller vesicles and shorter fronds, compared to other regions. Tidal conditions were the main environmental factors separating north coast sites from other sites and tidal regime was identified as the best predictor of morphological differences between regions. In contrast to other studies, we found little evidence that wave exposure was associated with morphological variation. Overall, our study emphasises the role of tidal conditions, associated with emersion stress during low tide, in affecting the morphology of intertidal seaweeds.This article is protected by copyright. All rights reserved.
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Ecologists seem predisposed to studying change because we are intuitively interested in dynamic systems, including their vulnerability to human disturbance. We contrast this disposition with the value of studying processes that work against change. Although powerful, processes that counter disturbance often go unexplored because they yield no observable community change. This stability results from compensatory processes which are initiated by disturbance; these adjust in proportion to the strength of the disturbance to prevent community change. By recognising such buffering processes, we might also learn to recognise the early warning signals of community shifts which are notoriously difficult to predict because communities often show little to no change before their tipping point is reached. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Seaweeds provide important ecosystem services in coastal areas, and loss of these macrophytes due to anthropogenic global change and warming is a worldwide concern. Fucus vesiculosus L. (Phaeophyceae) is the most abundant and hence ecologically most important primary producer, carbon sink and habitat provider in the western Baltic Sea. Therefore, we used this keystone species to test phenotypic acclimation of physiological performance traits (growth, photosynthesis and metabolites) of F. vesiculosus apices in a well-defined and highly resolved temperature gradient (5–29 °C), supported by highly temporally resolved measurements. Temperature requirements of growth and photosynthesis were evaluated in three weeks exposure experiments, and changing tolerance ranges for survival over time were determined. Fucus vesiculosus was able to grow and survive over a temperature range from 5 to 26 °C without any injury or visible damage of the apical growing meristem over all three weeks. However, at higher water temperatures (≥ 27 °C) growth rapidly decreased from day three onwards and progressive necrosis was observed at 28 and 29 °C. Stress-induced decrease in growth rate was already indicated by the effective quantum yield of chlorophyll fluorescence of photosystem II (PSII) several days in advance. Optimal temperature for photosynthesis (24 °C), measured as electron transport rate, was higher compared to that for growth (15–20 °C). Accordingly, the concentration of mannitol, the main product of photosynthesis, increased with higher temperatures. Understanding physiological responses of keystone macroalgae with respect to temperature and time is important, because rising global temperatures and summer heat wave frequencies and duration may affect the ecological functions of F. vesiculosus in the western Baltic Sea.
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On the basis of literature data and new morphological and ecological studies, the reinstatement of species rank for the Black Sea endemic species Cystoseira bosphorica is proposed. Previously reduced to a simple form of the Mediterranean endemic species C. crinita, this member of the caespitose Cystoseira group without spinose-like appendages clearly differs from C. crinita by having the axes long with smooth and prominent apices, the branches with numerous and slightly prominent cryptostomates, the aerocysts frequent, large, oval to subconical-broader at the apex, with 2 or more apical outgrowths, and by the receptacles long, cylindrical-tuberculate, simple or bifid, with apices blunt bearing sometimes a short lateral sub-apical spine. The species that shares the greatest number of characters with C. bosphorica is not C. crinita but the Mediterranean endemic species C. barbatula; however, this latter species clearly differs from C. bosphorica by the constant absence of aerocysts, the filiform branches with prominent and spaced cryptostomates, and by the receptacles smaller, compact, simple, humpy and subulate with sometimes 1-2 long lateral spine-like appendages.
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Coastal systems are increasingly threatened by multiple local anthropogenic and global climatic stressors. With the difficulties in remediating global stressors, management requires alternative approaches that focus on local scales. We used manipulative experiments to test whether reducing local stressors (sediment load and nutrient concentrations) can improve the resilience of foundation species (canopy algae along temperate rocky coastlines) to future projected global climate stressors (high wave exposure, increasing sea surface temperature), which are less amenable to management actions. We focused on Fucoids (Cystoseira barbata) along the north-western Adriatic coast in the Mediterranean Sea because of their ecological relevance, sensitivity to a variety of human impacts, and declared conservation priority. At current levels of sediment and nutrients, C. barbata showed negative responses to the simulated future scenarios of high wave exposure and increased sea surface temperature. However, reducing the sediment load increased the survival of C. barbata recruits by 90.24% at high wave exposure while reducing nutrient concentrations resulted in a 20.14% increase in the survival and enhanced the growth of recruited juveniles at high temperature. We conclude that improving water quality by reducing nutrient concentrations, and particularly the sediment load, would significantly increase the resilience of C. barbata populations to projected increases in climate stressors. Developing and applying appropriate targets for specific local anthropogenic stressors could be an effective management action to halt the severe and ongoing loss of key marine habitats.
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Biological responses to climate change are typically communicated in generalized terms such as poleward and altitudinal range shifts, but adaptation efforts relevant to management decisions often require forecasts that incorporate the interaction of multiple climatic and nonclimatic stressors at far smaller spatiotemporal scales. We argue that the desire for generalizations has, ironically, contributed to the frequent conflation of weather with climate, even within the scientific community. As a result, current predictions of ecological responses to climate change, and the design of experiments to understand underlying mechanisms, are too often based on broad-scale trends and averages that at a proximate level may have very little to do with the vulnerability of organisms and ecosystems. The creation of biologically relevant metrics of environmental change that incorporate the physical mechanisms by which climate trains patterns of weather, coupled with knowledge of how organisms and ecosystems respond to these changes, can offer insight into which aspects of climate change may be most important to monitor and predict. This approach also has the potential to enhance our ability to communicate impacts of climate change to nonscientists and especially to stakeholders attempting to enact climate change adaptation policies.
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Epiphytism is a strategy by which opportunistic species such as hydroids, escape the intense levels of com- petition in marine hard bottom communities. Species of the macroalgae Cystoseira have a seasonal turnover of the frond, and we hypothesise that epiphytic hydroids colonising such an unstable substrate might show some degree of specialisation. Here the first systematic study on hydroid-Cystoseira communities is presented. In particular, the seasonal and spatial dis- tribution of epiphytic hydroids on three species of Cystoseira at two sites of different wave exposure at Porto Cesareo (Ion- ian Sea/Italy) were investigated. Thirty-two hydroid species were recorded which are well known from other substrates and thus are not specific to Cystoseira; dominant species were all thecates. The influence of biological factors such as competi- tion and the structure and abundance of the host, seem to have little influence on the hydroid community. The factors of greatest influence were mostly abiotic: sedimentation rate, nutrient levels, temperature and most especially water movement. The importance of water movement was evident in the higher colonisation of algal stems, higher hydroid frequency, larger colonies, reduced colony height, species composition, and distribution on the stems at the wave-exposed site.
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Species distribution models (SDM) are a useful tool for predicting species range shifts in response to global warming. However, they do not explore the mechanisms underlying biological processes, making it difficult to predict shifts outside the environmental gradient where the model was trained. In this study, we combine correlative SDMs and knowledge on physiological limits to provide more robust predictions. The thermal thresholds obtained in growth and survival experiments were used as proxies of the fundamental niches of two foundational marine macrophytes. The geographic projections of these species' distributions obtained using these thresholds and existing SDMs were similar in areas where the species are either absent-rare or frequent and where their potential and realized niches match, reaching consensus predictions. The cold-temperate foundational seaweed Himanthalia elongata was predicted to become extinct at its southern limit in northern Spain in response to global warming, whereas the occupancy of southern-lusitanic Bifurcaria bifurcata was expected to increase. Combined approaches such as this one may also highlight geographic areas where models disagree potentially due to biotic factors. Physiological thresholds alone tended to over-predict species prevalence, as they cannot identify absences in climatic conditions within the species' range of physiological tolerance or at the optima. Although SDMs tended to have higher sensitivity than threshold models, they may include regressions that do not reflect causal mechanisms, constraining their predictive power. We present a simple example of how combining correlative and mechanistic knowledge provides a rapid way to gain insight into a species' niche resulting in consistent predictions and highlighting potential sources of uncertainty in forecasted responses to climate change. This article is protected by copyright. All rights reserved.
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Identifying the type and strength of interactions between local anthropogenic and other stressors can help to set achievable management targets for degraded marine ecosystems and support their resilience by identifying local actions. We undertook a meta-analysis, using data from 118 studies to test the hypothesis that ongoing global declines in the dominant habitat along temperate rocky coastlines, forests of canopy-forming algae and/or their replacement by mat-forming algae are driven by the non-additive interactions between local anthropogenic stressors that can be addressed through management actions (fishing, heavy metal pollution, nutrient enrichment and high sediment loads) and other stressors (presence of competitors or grazers, removal of canopy algae, limiting or excessive light, low or high salinity, increasing temperature, high wave exposure, and high UV or CO2), not as easily amenable to management actions. In general, the cumulative effects of local anthropogenic and other stressors had negative effects on the growth and survival of canopy-forming algae. Conversely, the growth or survival of mat-forming algae was either unaffected or significantly enhanced by the same pairs of stressors. Contrary to our predictions, the majority of interactions between stressors were additive. There were however synergistic interactions between nutrient enrichment and heavy metals, the presence of competitors, low light, and increasing temperature, leading to amplified negative effects on canopy-forming algae. There were also synergistic interactions between nutrient enrichment and increasing CO2 and temperature leading to amplified positive effects on mat-forming algae. Our review of the current literature shows that management of nutrient levels, rather than fishing, heavy metal pollution or high sediment loads, would provide the greatest opportunity for preventing the shift from canopy to mat-forming algae, particularly in enclosed bays or estuaries because of the higher prevalence of synergistic interactions between nutrient enrichment with other local and global stressors, and as such it should be prioritised.This article is protected by copyright. All rights reserved.
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Mechanistic models such as those based on dynamic energy budget (DEB) theory are emergent ecomechanics tools to investigate the extent of fitness in organisms through changes in life history traits as explained by bioenergetic principles. The rapid growth in interest around this approach originates from the mechanistic characteristics of DEB, which are based on a number of rules dictating the use of mass and energy flow through organisms. One apparent bottleneck in DEB applications comes from the estimations of DEB parameters which are based on mathematical and statistical methods (covariation method). The parameterisation process begins with the knowledge of some functional traits of a target organism (e.g. embryo, sexual maturity and ultimate body size, feeding and assimilation rates, maintenance costs), identified from the literature or laboratory experiments. However, considering the prominent role of the mechanistic approach in ecology, the reduction of possible uncertainties is an important objective. We propose a revaluation of the laboratory procedures commonly used in ecological studies to estimate DEB parameters in marine bivalves. Our experimental organism was Brachidontes pharaonis. We supported our proposal with a validation exercise which compared life history traits as obtained by DEBs (implemented with parameters obtained using classical laboratory methods) with the actual set of species traits obtained in the field. Correspondence between the 2 approaches was very high (>95%) with respect to estimating both size and fitness. Our results demonstrate a good agreement between field data and model output for the effect of temperature and food density on age-size curve, maximum body size and total gamete production per life span. The mechanistic approach is a promising method of providing accurate predictions in a world that is under in - creasing anthropogenic pressure. © Inter-Research 2013.
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Management of marine ecosystems requires spatial information on current impacts. In several marine regions, including the Mediterranean and Black Sea, legal mandates and agreements to implement ecosystem-based management and spatial plans provide new opportunities to balance uses and protection of marine ecosystems. Analyses of the intensity and distribution of cumulative impacts of human activities directly connected to the ecological goals of these policy efforts are critically needed. Quantification and mapping of the cumulative impact of 22 drivers to 17 marine ecosystems reveals that 20% of the entire basin and 60-99% of the territorial waters of EU member states are heavily impacted, with high human impact occurring in all ecoregions and territorial waters. Less than 1% of these regions are relatively unaffected. This high impact results from multiple drivers, rather than one individual use or stressor, with climatic drivers (increasing temperature and UV, and acidification), demersal fishing, ship traffic, and, in coastal areas, pollution from land accounting for a majority of cumulative impacts. These results show that coordinated management of key areas and activities could significantly improve the condition of these marine ecosystems.
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Cystoseira species are some of the most important marine ecosystem-engineers, forming extended canopies comparable to land forests. Such forests are sensitive to human disturbances, like the decrease in water quality, the coastal development and the outbreak of herbivores. Conspicuous historical declines have been reported in many regions and several Cystoseira species are presently protected by European Union (EU) environmental policies. The aim of this work was to synthesize the conservation perspectives of Cystoseira forests in the Mediterranean Sea, focusing on the opportunities offered by artificial restoration and highlighting the potential role of Marine Protected Areas (MPAs). MPAs give a better protection to healthy forests than non-managed sites and may be a source of propagules for natural recovery and/or for non-destructive artificial restoration of nearby damaged forests. MPAs lacking Cystoseira forests may also represent preferential sites for reforestation. We proposed a flow-chart for the conservation and a reasoned restoration of Cystoseira in the Mediterranean Sea. The successful conservation of Cystoseira forests is still possible, via raising public awareness on the role of Cystoseira and reducing human impacts on coastal ecosystems. Such actions have to be coupled with more specific large-scale management plans, encompassing restoration actions and enforcement of protection within MPAs.
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Anthropogenic disturbances affect natural populations and assemblages by interacting with fundamental ecological processes. Field experiments simulating the effects of human activities at the appropriate spatial and temporal scales are useful to understand these interactions and eventually to predict their ecological consequences. In the Mediterranean, low-shore habitats of rocky coasts are often dominated by canopy algae Cystoseira spp., but these species are frequently replaced by assemblages of turf-forming algae and mussel beds. We propose that anthropogenic disturbance is the proximate cause of loss of Cystoseira in the Mediterranean and that the disappearance of canopy algae causes an increase in cover of turf-forming species in disturbed habitats. Two hypotheses were investigated to test this proposition: (1) canopy algae will be dominant in relatively pristine habitats while turf-forming algae will be more abundant in urban areas, and (2) removal of canopy algae in unpolluted areas will result in the development of assemblages similar to those found in urban areas. We tested the first hypothesis by comparing patterns in abundance of Cystoseira and turf-forming algae at a number of locations in urban areas and in areas far from distinct sources of anthropogenic disturbance in the northwest Mediterranean. The second hypothesis was tested by conducting a large-scale manipulative experiment. involving the experimental removal of Cystoseira and several spatial and temporal repetitions of the manipulation. Turf-forming algae were always dominant in urban areas where Cystoseira was nearly absent. In contrast, canopy algae often dominated rocky shores in relatively pristine areas of the northwest Mediterranean The removal of Cystoseira generally caused an increase in the percentage cover of turf-forming algae and a decrease in the abundance of invertebrates. These changes were already evident 4 mo after manipulation and were consistent at the spatial and temporal scales examined in the study. Assemblages in cleared patches were qualitatively similar to those occurring where Cystoseira was naturally absent, but quantitative differences in the relative abundance of several taxa were still evident by the end of the study. These results support a cause-effect relationship between anthropogenic disturbance and loss of Cystoseira in the northwest Mediterranean and allow for quantitative predictions of the indirect consequences of disturbing canopy algae for the whole understory assemblage. Management options aimed at conserving these plants should simultaneously preserve other components of the assemblage.
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Based on the surface energy budget, the sea surface temperature (SST) variance is related to the product of three factors: the sum of the variances of surface radiative and turbulent energy fluxes and of ocean heat transport, an efficiency factor depending on the covariances among them, and a transfer factor involving the persistence of surface temperature via its lagged autocorrelation. These quantities are analyzed for current climate conditions based on results from the NCEP/NCAR reanalyses and a simulation with the CCCma coupled climate model. Potential changes with climate change are considered based on two quasi-equilibrium climate change integrations for which the forcing has been stabilized at years 2050 and 2100 values of the IS92a forcing scenario. The surface energy fluxes, which contribute to the variance of SST, are similar in the modelled and reanalyzed atmosphere but modelled temperature variance is conditioned on the thickness of the upper ocean model layer. Changes of SST variance with global warming show broad scale patterns with decreases in the tropical central-eastern Pacific and the northern extra-tropical Pacific, and increases in both the sub-tropical Pacific and mid-latitudes of the North Atlantic. The changes in SST variance are not associated only with changes in the variances of surface energy fluxes/transports but also with changes in the covariances among them and by changes in the temperature autocorrelation structure.
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Global stressors, including climate change, are a major threat to ecosystems, but they cannot be halted by local actions. Ecosystem management is thus attempting to compensate for the impacts of global stressors by reducing local stressors, such as overfishing. This approach assumes that stressors interact additively or synergistically, whereby the combined effect of two stressors is at least the sum of their isolated effects. It is not clear, however, how management should proceed for antagonistic interactions among stressors, where multiple stressors do not have an additive or greater impact. Research to date has focussed on identifying synergisms among stressors, but antagonisms may be just as common. We examined the effectiveness of management when faced with different types of interactions in two systems - seagrass and fish communities - where the global stressor was climate change but the local stressors were different. When there were synergisms, mitigating local stressors delivered greater gains, whereas when there were antagonisms, management of local stressors was ineffective or even degraded ecosystems. These results suggest that reducing a local stressor can compensate for climate change impacts if there is a synergistic interaction. Conversely, if there is an antagonistic interaction, management of local stressors will have the greatest benefits in areas of refuge from climate change. A balanced research agenda, investigating both antagonistic and synergistic interaction types, is needed to inform management priorities.
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In this work we give a contribution to the knowledge of benthic macroalgal assemblages of Giannutri, the southern island of the Tuscan Archipelago. A floristic list was obtained for the principal habitats: intertidal, shallow (0-22) and deep subtidal (30-50 m) on rocky bottom, Posidonia oceanica beds and cobble bottom (30-40 m). A total of 216 macroalgal species are identified, among them 29 Chlorophyta, 39 Fucophyceae and 148 Rhodophyta. Giannutri macroalgal communities resulted well structured and diversified, with a R/P ratio of 3.49. Well developed Lithophyllum byssoides structures and Cystoseira beds are the most interesting assemblages in shallower water. A rheophilous macroalgal community dominated by lathery Fucophyceae colonizes cobble bottom. Crustose and foliose Rhodophyta characterize coralligenous assemblage.
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Climate change is inducing shifts in species ranges across the globe. These can affect the genetic pools of species, including loss of genetic variability and evolutionary potential. In particular, geographically enclosed ecosystems, like the Mediterranean Sea, have a higher risk of suffering species loss and genetic erosion due to barriers to further range shifts and to dispersal. In this study, we address these questions for three habitat-forming seaweed species, Cystoseira tamariscifolia, C. amentacea and C. compressa, throughout their entire ranges in the Atlantic and Mediterranean regions. We aim to 1) describe their population genetic structure and diversity, 2) model the present and predict the future distribution and 3) assess the consequences of predicted future range shifts for their population genetic structure, according to two contrasting future climate change scenarios. A net loss of suitable areas was predicted in both climatic scenarios across the range of distribution of the three species. This loss was particularly severe for C. amentacea in the Mediterranean Sea (less 90% in the most extreme climatic scenario), suggesting that the species could become potentially at extinction risk. For all species, genetic data showed very differentiated populations, indicating low inter-population connectivity, and high and distinct genetic diversity in areas that were predicted to become lost, causing erosion of unique evolutionary lineages. Our results indicated that the Mediterranean Sea is the most threatened region, where future suitable Cystoseira habitats will become more limited. This is likely to have wider ecosystem impacts as there is a lack of species with the same ecological niche and functional role in the Mediterranean. The projected accelerated loss of already fragmented and disturbed populations and the long-term genetic effects highlight the urge for local scale management strategies that sustain the capacity of these habitat-forming species to persist despite climatic impacts while waiting for global emission reductions.
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Effective predictive and management approaches for species occurring in a metapopulation structure require good understanding of inter-population connectivity. In this study we ask whether population genetic structure of marine species with fragmented distributions can be predicted by stepping-stone oceanographic transport and habitat continuity, using as model an ecosystem-structuring brown alga, Cystoseira amentacea var. stricta. To answer this question, we analyzed the genetic structure and estimated the connectivity of populations along discontinuous rocky habitat patches in southern Italy, using microsatellite markers at multiple scales. In addition, we modelled the effect of rocky habitat continuity and ocean circulation on gene flow by simulating Lagrangian particle dispersal based on ocean surface currents allowing multigenerational stepping-stone dynamics. Populations were highly differentiated, at scales from few meters up to 1000s of kilometers. The best possible model fit to explain the genetic results combined current direction, rocky habitat extension and distance along the coast among rocky sites. We conclude that a combination of variables suitable habitat and oceanographic transport is a useful predictor of genetic structure. This relationship provides insight into the mechanisms of dispersal and the role of life history traits. Our results highlight the importance of spatially explicit modeling of stepping stone dynamics and oceanographic directional transport coupled with habitat suitability, to better describe and predict marine population structure and differentiation. This study also suggests the appropriate spatial scales for the conservation, restoration and management of species that are increasingly affected by habitat modifications. This article is protected by copyright. All rights reserved.
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Subtidal forests comprised of kelps and other canopy-forming macroalgae represent critically important marine habitats. Kelp forests exhibit high rates of primary productivity, magnified secondary productivity, support high levels of biodiversity and provide various ecosystem services. Compared with many other regions, kelp forests around the UK have been largely understudied despite their recognised importance and the possible impacts of environmental change factors. We conducted surveys at 12 kelp-dominated open-coast sites within four regions in the UK, spanning ~ 9° in latitude and ~ 3 °C in mean sea temperature. We used a combination of quadrat-scale abundance and percent cover data as well as transect-scale canopy cover estimates to quantify ecological structure at multiple spatial scales. Kelp forest structure varied significantly between sites (nested within region) and also between regions. Regional-scale differences were principally driven by a higher abundance/cover of Alaria esculenta at the colder northern regions (i.e. north and west Scotland), and the presence of the Lusitanian kelp Laminaria ochroleuca at some sites in the southernmost region (i.e. southwest England) but nowhere else. The kelp Laminaria hyperborea dominated all sites and varied significantly between sites but not regions. All assemblage-level and population-level response variables were highly variable between sites within regions, suggesting that environmental factors varying at corresponding spatial scales (e.g. wave exposure, turbidity, sedimentation) are important drivers of pattern. The detection of regional-scale variability suggests that predicted changes in ocean climate, particularly increased sea temperature, may lead to changes in kelp forest structure in the future, with poleward range contractions (for A. esculenta) and expansions (for L. ochroleuca) likely. However, as the distribution-abundance patterns of the assemblage dominant L. hyperborea did not vary predictably with ocean temperature at this spatial scale, the fundamental structure of these habitats may be more influenced by localised factors, at least in the short-term. The relative importance of multiple, concurrent environmental change factors in structuring UK kelp forests remains largely unknown.
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The influence of geomorphological features on the distribution of Cystoseira populations along the coasts of four pristine islands in the Tyrrhenian Sea (Italy, central Mediterranean) was studied by means of a model-based statistical analysis. The most relevant trait that determined the presence of these populations was found to be the coastline slope at the level of the infralittoral fringe. Our findings indicate that slopes above 60° reduce the likelihood of Cystoseira communities. The effects of the coastline slope on the CARLIT index are considered and discussed in view of these findings. Pending further studies on the implementation of the CARLIT index in the Mediterranean basin, we suggest that any changes to the procedure or the hasty multiplication of reference sites be avoided, and instead propose a simple empirical adjustment of the EQ values to be able to more accurately monitor coasts with steep slopes using this index.
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Although thermal performance is widely recognized to be pivotal in determining species' distributions, assessment of this performance is often based on laboratory acclimated individuals, neglecting their proximate thermal history. The thermal history of a species sums the evolutionary history and, importantly, the thermal events recently experienced by individuals, including short-term acclimation to environmental variations. Thermal history is perhaps of greatest importance for species inhabiting thermally challenging environments and therefore assumed to be living close to their thermal limits, such as in the tropics. To test the importance of thermal history the responses of the tropical oyster, Isognomon nucleus, to short term differences in thermal environments were investigated. Critical and lethal temperatures and oxygen consumption were improved in oysters which previously experienced elevated air temperatures and were associated with an enhanced heat shock response, indicating that recent thermal history affects physiological performance as well as inducing short-term acclimation to acute conditions. These responses were, however, associated with trades offs in feeding activity, with oysters which experienced elevated temperatures showing reduced energy gain. Recent thermal history, therefore, seems to rapidly invoke physiological mechanisms which enhance survival to short-term thermal challenge but also longer-term climatic changes and consequently need to be incorporated into assessments of species' thermal performances.
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Artificial structures are sprawling in marine seascapes as a result of burgeoning coastal populations, increasing development and energy demand, and greater risks from climate change, storm surges and sea level rise. Interest in designing marine developments that maintain vital ecosystems and critical services is growing, but progress requires understanding the factors that influence the ecological performance of these novel artificial habitats. We combined field observations and experiments along 500 km of the North Adriatic coastline to analyse the performance of artificial substrata as habitats to support canopy-forming algae belonging to the genus Cystoseira, among the most ecologically-relevant foundation species along rocky Mediterranean coastlines. We aimed to: clarify the underlying factors controlling the growth of Cystoseira in the artificial habitat; contrast the relative importance of these factors between artificial and natural habitats; and test the generality of the results across different sites and species of Cystoseira. We found that: i) the growth of canopy algae was significantly lower on artificial structures compared to rocky reefs; ii) such lower growth of canopy algae was not related to less favourable abiotic conditions but to higher biotic disturbance from both consumptive and non-consumptive interactions on the artificial structures compared to the natural reef; iii) this was consistent across different study sites and canopy-forming species. We conclude that biological factors influencing the growth of canopy algae, such as herbivory or other non-consumptive disturbances, can differ substantially between artificial and natural habitats. The unusually large and previously unreported biotic pressure characterizing many artificial structures can negatively affect their performance as habitats to support ecologically relevant, foundation species. Synthesis and applications. While nearly all considerations to improve the ecological performance of hard marine infrastructures focus on abiotic factors (e.g. construction materials, surface texture, habitat complexity or water quality) careful consideration of critical biotic factors is also needed to further progress the green engineering of sprawling marine infrastructures.
Article
A study of inter-population variation in vegetative morphology of Fucus vesiculosus L. populations from SW Finland has been carried out and the variation is described and quantified. The taxonomic status of an unusual population from Virolahti the eastern part of Gulf of Finland has also been assessed. Five populations of Fucus vesiculosus were sampled at peak fertility time from shores of different wave exposure. Nine vegetative characters were measured and analysed using principle component analysis and stepwise discriminant analysis. The plant width, distance between dichotomies, plant length, midrib and stipe width were the five most important distinguishing characters. The plants were classified with accuracy of 70% into the correct population. The morphology of Fucus vesiculosus appears to vary within a small scale due to the local factor, exposure; shorter plants with narrow fronds are found on exposed shores and plants from more exposed shores lack bladders. Reduced salinity level could partly explain the existence the dwarf morph of Fucus from eastern part of Gulf of Finland. However, it would be difficult to justify taxonomic recognition of any of these populations on morphology.