0000000000458124
AUTHOR
Chiara Bonaviri
Hydrodynamism and its influence on the reproductive condition of the edible sea urchin Paracentrotus lividus
Despite the large body of work published in the last two decades on the reproduction of the sea urchin Paracentrotus lividus, the reproductive aspects linked to hydrodynamic conditions and their influence on gonad production remain poorly understood. The present paper aims to evaluate the effect of hydrodynamism on the reproductive cycle of P. lividus. Variability in the gonadosomatic index (GSI) of P. lividus was estimated seasonally from 2007 to 2008 at two shallow sub-littoral flat basaltic areas at Ustica Island (Western Mediterranean). GSI was higher in the sites characterized by low hydrodynamism than in those with high hydrodynamism. Results also suggest a possible role for hydrodyna…
Preliminary data on movement of sea-urchins Paracentrotus lividus and Arbacia lixula in two habitats with different structural complexity.
Fish assemblages cope with ocean acidification in a shallow volcanic CO2 vent benefiting from an adjacent recovery area
Shallow CO2 vents are used to test ecological hypotheses about the effects of ocean acidification (OA). Here, we studied fish assemblages associated with Cymodocea nodosa meadows exposed to high pCO2/low pH conditions at a natural CO2 vent in the Mediterranean Sea. Using underwater visual census, we assessed fish community structure and biodiversity in a low pH site (close to the CO2 vent), a close control site and a far control site, hypothesising a decline in biodiversity and a homogenization of fish assemblages under OA conditions. Our findings revealed that fish diversity did not show a unique spatial pattern, or even significant relationships with pH, but correlated with seagrass leaf …
Notes on the fish assemblages present in the areas invaded by Caulerpa spp. (Ulvophyceae, Chlorophyta) along the Sicilian coasts
Dati preliminari sulla variabilità spazio-temporale di Paracentrotus lividus nell’ AMP “Capo Gallo Isola delle Femmine”
Exploring the impact of the invasive algae Caulerpa taxifolia var. distichophylla and C. cylindracea on the performance of the sea urchin Paracentrotus lividus.
Food selection of a generalist herbivore exposed to native and alien seaweeds
Understanding which factors influence the invasion of alien seaweed has become a central concern in ecology. Increasing evidence suggests that the feeding preferences of native herbivores influence the success of alien seaweeds in the new community. We investigated food selection of a generalist native grazer Paracentrotus lividus, in the presence of two alien seaweeds (Caulerpa cylindracea and Caulerpa taxifolia var. distichophylla) and two native seaweeds (Dictyopteris membranacea and Cystoseira compressa). Sea urchins were fed with six experimental food items: C. cylindracea, C. taxifolia var. distichophylla, a mixture of C. cylindracea and C. taxifolia var. distichophylla, D. membranace…
Escape reaction of the sea-urchins Paracentrotus lividus and Arbacia lixula from the sea star Marthasterias glacialis on different substrates with different structural complexity.
Increased water temperature decreases predation rate of an important sea star predator on sea urchins.
Fish-seastar facilitation leads to algal forest restoration on protected rocky reefs
AbstractAlthough protected areas can lead to recovery of overharvested species, it is much less clear whether the return of certain predator species or a diversity of predator species can lead to re-establishment of important top-down forces that regulate whole ecosystems. Here we report that the algal recovery in a Mediterranean Marine Protected Area did not derive from the increase in the traditional strong predators, but rather from the establishment of a previously unknown interaction between the thermophilic fish Thalassoma pavo and the seastar Marthasterias glacialis. The interaction resulted in elevated predation rates on sea urchins responsible for algal overgrazing. Manipulative ex…
Synergistic reduction of a native key herbivore performance by two non-indigenous invasive algae
Abstract Native generalist grazers can control the populations of non-indigenous invasive algae (NIIA). Here, it was found that the simultaneous consumption of two co-occurring NIIA, Caulerpa cylindracea and C. taxifolia var. distichophylla, hinders the grazing ability of the main Mediterranean herbivorous, the native sea urchin Paracentrotus lividus. The ingestion of any of the two NIIA alone did not produce any difference in sea urchin righting time with respect to usual algal diet. In contrast, the simultaneous consumption of both NIIA, which grow intermingled in nature and are consumed by P. lividus, retarded its righting behavior. Such result reveals substantial physiological stress in…
Arbacia
Sea urchins of the genus Arbacia are widely distributed throughout the world occurring in tropical, temperate and sub-Antartic zones. In the past, Arbacia has been the object of intensive investigations in cell biology and biochemistry of fertilization and early development. Renewed interest in the genus Arbacia arose mainly due to its ecological role and its unusual geographic distribution. All the six species of Arbacia are omnivorous with a strong tendency to carnivory. Recent manipulative and morpho-functional studies demonstrated that Arbacia species play an important role in the ecology of rocky reefs. They maintain barren areas by scraping either fleshy and encrusting algae and anima…
Distribution and diet of Marthasterias glacialis at Ustica Island MPA
Distribution and diet of Marthasterias glacialis was studied at Ustica Island MPA. We conducted observations of the asteroid along the upper infralittoral zone using random parallel transects. M. glacialis was more abundant at study sites characterized by low densities of erect algae. Most frequent prey species was a bivalve and sea urchins
Benthic megafauna distribution in two different algal assemblages of the Ustica Island rocky infralittoral (NW Mediterranean)
Functional traits of two co-occurring sea urchins across a barren/forest patch system
Abstract Temperate rocky reefs may occur in two alternative states (coralline barrens and erect algal forests), whose formation and maintenance are often determined by sea urchin grazing. The two sea urchin species Paracentrotus lividus and Arbacia lixula are considered to play a similar ecological role despite their differing morphological traits and diets. The patchy mosaic areas of Ustica Island, Italy, offer an ideal environment in which to study differences in the performance of P. lividus and A. lixula in barren versus forest states. Results show that the two sea urchin species differ in diet, trophic position, grazing adaptation, movement ability and fitness in both barren and forest…
Protection effect on distribution patterns of Paracentrotus lividus and Arbacia lixula in the “Plemmirio” Marine Protected Area
The operational sex ratio of the sea urchin Paracentrotus lividus populations: the case of the Mediterranean marine protected area of Ustica Island (Tyrrhenian Sea, Italy)
We investigated, with a series of field and laboratory observations, the possible effect of the starfish Marthasteria glacialis predation on the operational sex ratio (OSR), i.e. the number of sexually mature males divided by the total number of sexually mature adults of both sexes at any one time, of the edible sea urchin Paracentrotus lividus. The OSR was estimated three times during the sea urchin summer spawning period (July 2004, June 2005 and July 2006) on barren substrates of Ustica Island Marine Protected Area (Southern Tyrrhenian Sea, Italy). Four sites were selected: two characterized by high M. glacialis density (take zone C) and two controls with low starfish density (no-take zo…
Antioxidant response, induced by the invasive algae Caulerpa distichophylla and C. racemosa, in the sea urchin Paracentrotus lividus
Effetti della raccolta ricreativa sulla distribuzione di Paracentrotus lividus e Arbacia lixula nell’amp “Isola di Ustica” (Mediterraneo occidentale, Italia).
The rise of thermophilic sea urchins and the expansion of barren grounds in the Mediterranean Sea
Recent ecological studies have shown a strong relation between temperature, echinoids and their grazing effects on macro-algal communities. In this study, we speculate that climate warming may result in an increasingly favourable environment for the reproduction and development of the sea urchin Arbacia lixula. The relationship between increased A. lixula density and the extent of barren grounds in the Mediterranean Sea is also discussed.
Macroalgal forest vs sea urchin barren: Patterns of macro-zoobenthic diversity in a large-scale Mediterranean study.
Abstract The study aimed at contributing to the knowledge of alternative stable states by evaluating the differences of mobile and sessile macro-zoobenthic assemblages between sea urchin barrens and macroalgal forests in coastal Mediterranean systems considering a large spatial scale. Six sites (100 s km apart) were selected: Croatia, Montenegro, Sicily (Italy), Sardinia (Italy), Tuscany (Italy), and Balearic Islands (Spain). A total of 531 taxa, 404 mobile and 127 sessile macro-invertebrates were recorded. Overall, 496 and 201 taxa were found in macroalgal forests and in barrens, respectively. The results of this large-scale descriptive study have met the expectation of lower macrofauna co…
Climate change potentially affect keystone predation in subtidal system.
Preliminary assessment of the impact of an extreme storm on catalan mediterranean benthic communities
Macroalgal assemblage type affects predation pressure on sea urchins by altering adhesion strength.
In the Mediterranean, sea breams are the most effective Paracentrotus lividus and Arbacia lixula predators. Generally, seabreams dislodge adult urchins from the rocky substrate, turn them upside down and crush their tests. Sea urchins may respond to fish attacks clinging tenaciously to the substratum. This study is the first attempt to investigate sea urchin adhesion strength in two alternative algal assemblages of the rocky infralittoral and valuated its possible implication for fish predation. We hypothesized that (1) sea urchin adhesion strength is higher in rocky shores dominated by encrusting macro-algae (ECA) than in erected macro algae (EMA); (2) predation rates upon sea urchins are …
Remarkable presence of Aplysia punctata (Mollusca, Opisthobranchia, Anaspidea) in the Ustica Island MPA (Western Mediterranean, Italy)
Effetti del comportamento di Thalassoma pavo sul successo predatorio di Marthasterias glacialis
Diet and trophic interactions of Paracentrotus lividus and Arbacia lixula in two alternative stable states of the Mediterranean rocky sublittoral community
Espansione di Caulerpa taxifolia (Caulerpales, Ulvophyceae) lungo le coste dell'Isola di Favignana
Studio preliminare sulla diversità della megafauna dei barren mediterranei
Leading role of the sea urchin Arbacia lixula in maintaining the barren state in southwestern Mediterranean
Sympatric sea urchin species are usually considered to belong to the same grazer guild. Nevertheless, their role in community dynamics may vary due to species-specific morphological traits, feeding preferences and foraging behavior. In the Mediterranean Sea, the two species Paracentrotus lividus and Arbacia lixula co-occur in barren areas. Whereas P. lividus is usually considered responsible for creating a barren ground, the roles of the two sea urchin species in its maintenance are currently unclear. The relative and combined effects of P. lividus and A. lixula on maintaining the benthic community in the barren state were tested experimentally, using orthogonal exclusion of the two species…
Mediterranean sponges from shallow subtidal rocky reefs: Cystoseira canopy vs barren grounds
Abstract Porifera richness was investigated in Cystoseira canopies vs barren grounds considering different substrates at 6 areas in the Central-Western Mediterranean Sea. In total 31 sponge taxa were recorded at 2–7 m depth and the sponge community structure and composition were characterized by a notably low richness with 25 taxa in the Cystoseira forest and 15 in the barren area. As for the sponge habitus, the massive sponges were dominant in both facies, whereas encrusting, and cavity dwelling sponges were found in higher numbers in the Cystoseira forest. Results revealed that rocky substrata seem to play a key role in driving the sponge community composition and diversity in both facies…
Sea temperature and echinoid Arbacia lixula (L.) population fluctuations on Ustica Island MPA
Size-dependent predation of the mesopredator Marthasterias glacialis (L.) (Asteroidea)
Asteroids are largely recognized as important predators in all of the world’s oceans and for this reason, they play a crucial role in shaping the structure and functioning of benthic ecosystems. The spiny starfish Marthasterias glacialis is generally considered a voracious predator of molluscs, in particular bivalves. Using field observations and carbon (δ13C) and nitrogen (δ15N) stable isotopes, we explored possible changes in diet in relation to size of M. glacialis. Data were collected at Ustica Island (Southern Tyrrhenian Sea) from June 2008 to June 2010. M. glacialis showed a size shift in feeding preferences due to different use of food items: bivalves, Columbella rustica, Euthria cor…
Sex ratio operativa della popolazione di Paracentrotus lividus (Lam.) nell’AMP Isola di Ustica
Nell’AMP ”Isola di Ustica” l'instaurazione del regime di protezione, e quindi del divieto di prelievo, ha provocato un aumento della densità del riccio edule Paracentrotus lividus (Lam.) con conseguenze negative sulle comunità algali. L’intenso pascolo di questi echinidi regolari ha infatti trasformato la fascia superficiale sommersa in un barren ground, area a bassa complessità e diversità. Una buona stima della sex ratio operativa (OSR) di P. lividus può chiarire aspetti importanti della dinamica di popolazione di questa specie ed essere di notevole aiuto in una logica di intervento gestionale. Scopo del lavoro è stato quello di valutare la OSR della popolazione di P. lividus presente nel…
Role of two co-occurring Mediterranean sea urchins in the formation of barren from Cystoseira canopy
Abstract In the Mediterranean Sea the co-occurring sea urchins Paracentrotus lividus and Arbacia lixula are usually considered to share the same ecological role in the formation of barren from Cystoseira canopy. However, their foraging ability may vary due to feeding behavior and species-specific morphological traits. The relative effects of P. lividus and A. lixula on Cystoseira canopy was tested experimentally both in the laboratory, at a density of about 20 ind./m 2 , and in the field by gut content analysis. Field and laboratory results show that A. lixula is unable to affect Cystoseira spp. Furthermore, these results confirmed the great ability of P. lividus to consume Cystoseira canop…
Warmer temperatures reduce the influence of an important keystone predator
Predator–prey interactions may be strongly influenced by temperature variations in marine ecosystems. Consequently, climate change may alter the importance of predators with repercussions for ecosystem functioning and structure. In North-eastern Pacific kelp forests, the starfish Pycnopodia helianthoides is known to be an important predator of the purple sea urchin Strongylocentrotus purpuratus. Here we investigated the influence of water temperature on this predator–prey interaction by: (i) assessing the spatial distribution and temporal dynamics of both species across a temperature gradient in the northern Channel Islands, California, and (ii) investigating how the feeding rate of P. heli…
Native predators control the population of an invasive crab in no-take marine protected areas
1. The resistance of an ecosystem to species invasion is considered to be related to the abundance and diversity of native species i.e. biotic resistance hypothesis). Theory predicts that the high native diversity in pristine systems can hinder the establishment and/or the spread of non‐native species through direct and indirect mechanisms (e.g. through competitive and/or predatory interactions). 2. Here we tested whether predation provides higher resistance to invasion by the Percnidae crab Percnon gibbesi (H. Milne Edwards, 1853) in protected native communities, compared with exploited ones. Specifically, this study aimed to compare: (i) the abundance and diversity of potential predator a…
Effect of the two co-occurring sea-urchins Paracentrotus lividus and Arbacia lixula on the maintenance of the barren habitat in the Ustica MPA (NW Mediterranean).
New record of Caulerpa taxifolia (Caulerpales, Ulvophyceae) in the South-western Sicilian waters (Italy).
Analisi preliminare della pesca artigianale nell'area del Biscione (Sicilia sud-occidentale).
Protection effects on feeding and reproduction of Paracentrotus lividus and Arbacia lixula on barren grounds at Ustica Island MPA (Western Mediterranean, Italy).
Effetto del substrato sulla tenacità di attacco e sulla predazione dei ricci Paracentrotus lividus (Lmk) nell’AMP Isola di Ustica.
Hiding behaviour ofOxynoe olivacea(Mollusca: Opisthobranchia: Sacoglossa) in the invasive seaweedCaulerpa taxifolia
The occurrence of the invasive seaweed Caulerpa taxifolia in the Straits of Messina (Italy) provides an excellent opportunity to examine the spatial and temporal patterns of abundance of the endemic Mediterranean sacoglossan Oxynoe olivacea. Densities of this species were recorded in March, June and October 2000 on three different habitats: the underside of boulders (UNB), the upper side of boulders (UPB), and the surface of concrete blocks (CB). Results showed that in March, O. olivacea was consistently more abundant on UNB whereas in June it was present exclusively on CB. The density of O. olivacea was similar in the three habitats in October. The hiding behaviour of O. olivacea and its s…
Dinamica dell’ecosistema roccioso dell’AMP “Isola di Ustica” nell’ultimo cinquantennio attraverso la conoscenza dei veterani del mare.
Stato e conservazione di Paracentrotus lividus nell’ AMP Plemmirio.
A preliminary study on temporal and spatial patterns of variability in Paracentrotus lividus and Arbacia lixula in the Ustica Island MPA (western Mediterranean, Italy). “ Le scienze naturali,economiche e giuridiche nello studio per la gestione degli ambienti acquatici.
Unveiling the diet of the thermophilic starfish Ophidiaster ophidianus (Echinodermata: Asteroidea) combining visual observation and stable isotopes analysis
The starfish Ophidiaster ophidianus is an Atlanto-Mediterranean species protected under the EU’s Habitat Directive. Despite the wide distribution and the current range of expansion of this thermophilic species in the northern Mediterranean Sea, nothing is known about its diet. Using field observations and δ13C and δ15N Stable Isotopes Analysis (SIA), the feeding habits of O. ophidianus were explored in two Mediterranean rocky reef areas located in the southern Tyrrhenian (Ustica Island, Italy) and the eastern Adriatic Sea (Molunat, Croatia). According to field observations, O. ophidianus preys mainly on crustose coralline algae (CCA) and the keratose sponge Ircinia variabilis in both areas.…
Micropredation on sea urchins as a potential stabilizing process for rocky reefs
Rocky reefs can shift from forest, a state dominated by erect algae with high biodiversity, to barren, an impoverished state dominated by encrusting algae. Sea urchins, abundant in barrens, are usually held responsible for the maintenance of this state. Predation by large fish can revert the barren state to forest by controlling sea urchin populations. However, the persistence of a community state sometimes seems to be independent from the presence of such large predators, suggesting the existence of other, unknown mechanisms ensuring their stability. Theoretical studies suggest that the settler stage of sea urchins is determinant for maintaining a given rocky reef state. In this study, we …
Population structure of the sea urchins Paracentrotus lividus and Arbacia lixula across a depth gradient
Sea urchins are considered to have a paramount role in structuring rocky shallow communities. Under certain conditions, grazing by sea-urchins has been reported to produce a shift from macroalgae-dominated communities to barren habitat dominated by encrusting algae. However, this process is not recorded at all depths. The effect of depth on the structure of the sea-urchin populations may be thus a key feature to understand the origin and maintenance of the barren habitat within certain depths. In the present study, the structure of Paracentrotus lividus (Lam.) and Arbacia lixula (L.) populations are analyzed across a depth gradient in the Ustica Island MPA (NW Mediterranean), where the barr…
Biodiversity in canopy-forming algae: Structure and spatial variability of the Mediterranean Cystoseira assemblages
Abstract In the Mediterranean Sea, Cystoseira species are the most important canopy-forming algae in shallow rocky bottoms, hosting high biodiverse sessile and mobile communities. A large-scale study has been carried out to investigate the structure of the Cystoseira-dominated assemblages at different spatial scales and to test the hypotheses that alpha and beta diversity of the assemblages, the abundance and the structure of epiphytic macroalgae, epilithic macroalgae, sessile macroinvertebrates and mobile macroinvertebrates associated to Cystoseira beds changed among scales. A hierarchical sampling design in a total of five sites across the Mediterranean Sea (Croatia, Montenegro, Sardinia,…
Crushing predation of the spiny star Marthasterias glacialis upon the sea urchin Paracentrotus lividus
Literature data report that only fish predators are able to crush sea urchin tests in Mediterranean rocky reefs. This experimental study showed that the spiny star Marthasterias glacialis is able to break Paracentrotus lividus tests and that the breaking event is more likely to occur for small-sized sea urchins than for big ones. Our results show that the role of M. glacialis in regulating P. lividus population density can be important in specific locations. They may have important implications, moreover, for the use of tethering techniques aimed at identifying predator types of sea urchins.
Predation on sea urchin by Marthasterias glacialis (L.).
Relative role of fish vs. starfish predation in controlling sea urchin populations in Mediterranean rocky shores
In the Mediterranean, fishing bans generally allow the recovery of populations of sea urchin predators, such as the seabreams Diplodus sargus and D. vulgaris, promoting the transformation of overgrazed communities into ones dominated by erect macroalgae. However, in the marine reserve on Ustica Island (SW Italy) the opposite trend has occurred in the upper infralittoral community, and urchin barrens formed after the cessation of fishing activities. We hypothesized that (1) the natural scarcity of the 2 seabream species leads to a low predation rate on sea urchins at Ustica, and (2) predation rate varies with depth, due to differences in the predator assemblages. Tethering experiments were c…
Ruolo ecologico degli Asteroidei in due comunità dell'infralitorale superiore dell'Isola di Ustica
Gli asteroidi sono predatori che si ritrovano comunemente negli ecosistemi marini di fondo duro e mobile. Nell’Area Marina Protetta “Isola di Ustica” il divieto di raccolta del riccio edule Paracentrotus lividus nell’infralitorale superiore, ha determinato la sostituzione della comunità ad alghe fotofile erette con una comunità dominata da alghe incrostanti e ricci (barren) in gran parte dell’isola. Tre specie di asteroidi, Marthasterias glacialis, Ophidiaster ophidianus e Coscinasterias tenuispina, si ritrovano comunemente sia nell’habitat dominato dal barren che in quello dove rimangono elevate coperture ad alghe fotofile erette. Sono state studiate la distribuzione e le abitudini aliment…
First record of Caulerpa taxifolia (Caulerpales, Ulvophyceae) in the western Sicilian waters (Italy).
Visual cues as the key for driving ornate wrasse response behavior
The effects of recreational Paracentrotus lividus fishing on distribution patterns of sea urchins at Ustica Island MPA (Western Mediterranean, Italy)
This study evaluated the effects of recreational Paracentrotus lividus fishing on average density and size of this edible sea urchin, and its indirect effects on Arbacia lixula on barren substrates of Ustica Island MPA (SW Italy, Mediterranean Sea). Size, single and pooled species densities, density of large individuals (>40 mm long) and small individuals (<20 mm long) of the two species were estimated by scuba diving in autumn 2003, spring and summer 2004 at two sites impacted by P. lividus fishing (Punta Cavazzi and Pagliaro, take zone C) and one control (Cala Sidoti, no take zone). Two samplings were performed in each season. We found that reduced densities of P. lividus and A. lixula oc…