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Dive into the research topics where Davide Agnetta is active.

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Featured researches published by Davide Agnetta.


Chemistry and Ecology | 2011

The rise of thermophilic sea urchins and the expansion of barren grounds in the Mediterranean Sea

Paola Gianguzza; Davide Agnetta; Chiara Bonaviri; Francesco Di Trapani; Giulia Visconti; Fabrizio Gianguzza; Silvano Riggio

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.


Marine Environmental Research | 2010

Macroalgal assemblage type affects predation pressure on sea urchins by altering adhesion strength.

Paola Gianguzza; Chiara Bonaviri; G. Milisenda; A. Barcellona; Davide Agnetta; T. Vega Fernández; Fabio Badalamenti

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 macroalgae (ECA) than in erected macroalgae (EMA); (2) predation rates upon sea urchins are lower in ECA than in EMA; and (3) predation rate on A. lixula is lower than that on P. lividus. We observed that attachment tenacity of both sea urchins was higher in ECA than EMA and that A. lixula exhibited a stronger attachment tenacity than P. lividus in ECA. Results supported the importance of adhesion strength, as efficient defence against sea bream attacks, only for, P. lividus. A. lixula adhesion strength does not seem to be an important factor in avoiding fish predation, possibly because of the low palatability of the species. These patterns may deserve particular interest in understanding the processes responsible for the maintenance of sea urchin barrens that are dominated by ECA assemblage.


Marine Environmental Research | 2013

Hydrodynamism and its influence on the reproductive condition of the edible sea urchin Paracentrotus lividus

Paola Gianguzza; Chiara Bonaviri; Ermelinda Prato; Giovanni Fanelli; Mariachiara Chiantore; Davide Privitera; Filippo Luzzu; Davide Agnetta

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 hydrodynamism in triggering processes of resource limitation (food shortage), probably by interfering with P. lividus feeding activity.


Scientific Reports | 2015

Fish-seastar facilitation leads to algal forest restoration on protected rocky reefs.

Nicola Maria Galasso; Chiara Bonaviri; Francesco Di Trapani; Mariagrazia Picciotto; Paola Gianguzza; Davide Agnetta; Fabio Badalamenti

Although 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 experiments and field observations revealed that the proximity of the seastars triggered an escape response in sea urchins, extending their tube feet. Fishes exploited this behavior by feeding on the exposed tube feet, thus impairing urchin movement, and making them vulnerable to predation by the seastars. These findings suggest that predator diversity generated by MPA establishment can activate positive interactions among predators, with subsequent restoration of the ecosystem structure and function through cascading consumer impacts.


Marine Environmental Research | 2016

Determinants of Paracentrotus lividus sea urchin recruitment under oligotrophic conditions: Implications for conservation management

Silvia Oliva; Simone Farina; Stefania Pinna; Ivan Guala; Davide Agnetta; Pierre Antoine Ariotti; Francesco Mura; Giulia Ceccherelli

Sea urchins may deeply shape the structure of macrophyte-dominated communities and require the implementation of sustainable management strategies. In the Mediterranean, the identification of the major recruitment determinants of the keystone sea urchin species Paracentrotus lividus is required, so that source areas of the populations can be identified and exploitation or programmed harvesting can be spatially managed. In this study a collection of eight possible determinants, these encompassing both the biotic (larvae, adult sea urchins, fish, encrusting coralline algae, habitat type and spatial arrangement of habitats) and abiotic (substrate complexity and nutritional status) realms was considered at different spatial scales (site, area, transect and quadrat). Data from a survey including sites subject to different levels of human influence (i.e. from urbanized to protected areas), but all corresponding to an oligotrophic and low-populated region were fitted by means of a generalized linear mixed model. Despite the extensive sampling effort of benthic quadrats, an overall paucity of recruits was found, recruits being aggregated in a very small number of quadrats and in few areas. The analysis of data detected substrate complexity, and adult sea urchin and predatory fish abundances as the momentous determinants of Paracentrotus lividus recruitment. Possible mechanisms of influence are discussed beyond the implications of conservation management.


Italian Journal of Zoology | 2013

Hiding behaviour of Oxynoe olivacea (Mollusca: Opisthobranchia: Sacoglossa) in the invasive seaweed Caulerpa taxifolia

Paola Gianguzza; K. R. Jensen; Chiara Bonaviri; Davide Agnetta; Renato Chemello

Abstract 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 seeming disappearance in March did not coincide with a decline of abundance of phylloids of C. taxifolia. The results represent an important basis for further studies devoted to the investigation of abundance of these marine invertebrates, which has been traditionally thought of as unpredictable.


Journal of Sea Research | 2013

Functional traits of two co-occurring sea urchins across a barren/forest patch system

Davide Agnetta; Chiara Bonaviri; Fabio Badalamenti; C. Scianna; Salvatrice Vizzini; Paola Gianguzza


Estuarine Coastal and Shelf Science | 2015

Role of two co-occurring Mediterranean sea urchins in the formation of barren from Cystoseira canopy

Davide Agnetta; Fabio Badalamenti; Giulia Ceccherelli; F. Di Trapani; Chiara Bonaviri; Paola Gianguzza


Marine Biology | 2016

Size-dependent predation of the mesopredator Marthasterias glacialis (L.) (Asteroidea)

Paola Gianguzza; F. Di Trapani; Chiara Bonaviri; Davide Agnetta; Salvatrice Vizzini; Fabio Badalamenti


Archive | 2016

Relazione finale per il Progetto RITMARE "Studio della rete trofica della comunità ittica in aree soggette a diverso livello di sfruttamento della pesca"

Carlo Pipitone; Davide Agnetta

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Agnetta D

University of Palermo

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Fabio Badalamenti

Institute of Rural Management Anand

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Fabio Badalamenti

Institute of Rural Management Anand

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