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

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 patches. We confirmed herbivory in P. lividus and omnivory with a strong tendency to carnivory in A. lixula. When the sea urchin escape response to a predator was triggered, P. lividus responded faster in barren and forest patches. Forest patch restricted movement, especially in A. lixula (velocity in barren ≈10-fold greater than in forest). A large Aristotle's lantern, indicative of durophagy, confirmed adaptation of A. lixula to barren state

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

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

Kentucky Dream / music by S. R. Henry; words by Agnetta Floris and D. Onivas; translated by Frank H. Warden

Cover: a Photo of Mabel Norman; Publisher: Jos. W. Stern and Co. (New York)https://egrove.olemiss.edu/sharris_c/1149/thumbnail.jp

Interactive effects of fishing effort reduction and climate change in a central Mediterranean fishing area: Insights from bio-economic indices derived from a dynamic food-web model

Disentangling the effects of mixed fisheries and climate change across entire food-webs requires a description of ecosystems using tools that can quantify interactive effects as well as bio-economic aspects. A calibrated dynamic model for the Sicily Channel food web, made up of 72 functional groups and including 13 fleet segments, was developed. A temporal simulation until 2050 was conducted to evaluate the bio-economic interactive effects of the reduction of bottom trawling fishing effort by exploring different scenarios that combine fishery and climate change. Our results indicate that direct and indirect effects produce a net increase in biomass of many functional groups with immediate decline of trawlers’ catches and economic incomes, followed by a long term increase mainly due to biomass rebuilding of commercial species which lasts 5-10 years after fishing reduction. Synergistic and antagonistic effects caused by changes in the fishing effort and in climate characterize a specific functional group’s response in biomass which, in turn, modulate also the catch and income of the other fleets, and especially of those sharing target resources. However, trawler’s intra-fleet competition is higher than the others fleet effects. In the medium term, the effects of fishing effort reduction are higher than those of climate change and seem to make exploitation of marine resources more sustainable over time and fishery processes more efficient by improving ecosystem health

Detection of the Cherenkov light diffused by Sea Water with the ULTRA Experiment

The study of Ultra High Energy Cosmic Rays represents one of the most challenging topic in the Cosmic Rays and in the Astroparticle Physics fields. The interaction of primary particles with atmospheric nuclei produces a huge Extensive Air Shower together with isotropic emission of UV fluorescence light and highly directional Cherenkov photons, that are reflected/diffused isotropically by the impact on the Earth's surface or on high optical depth clouds. For space-based observations, detecting the reflected Cherenkov signal in a delayed coincidence with the fluorescence light improves the accuracy of the shower reconstruction in space and in particular the measurement of the shower maximum, giving a strong signature for discriminating hadrons and neutrinos, and helping to estimate the primary chemical composition. Since the Earth's surface is mostly covered by water, the ULTRA (UV Light Transmission and Reflection in the Atmosphere)experiment has been designed to provide the diffusing properties of sea water, overcoming the lack of information in this specific field. A small EAS array, made up of 5 particle detectors, and an UV optical device, have been coupled to detect in coincidence both electromagnetic and UV components. The detector was in operation from May to December, 2005, in a small private harbor in Capo Granitola (Italy); the results of these measurements in terms of diffusion coefficient and threshold energy are presented here.Comment: 4 pages, 3 figures, PDF format, Proceedings of 30th ICRC, International Cosmic Ray Conference 2007, Merida, Yucatan, Mexico, 3-11 July 200

Fenomeno Caulerpa 2010-2013. Rapporto sull'evoluzione delle specie aliene nel Canale di Sicilia

Gli studi effettuati da ARPA-Sicilia, ISPRA e CNR-IAMC hanno perseguito l’obiettivo principale di monitorare e valutare l’impatto della diffusione delle alghe indagate, attraverso l’analisi dell’evoluzione spazio-temporale del fenomeno e la caratterizzazione eco-tossicologica delle aree di pesca maggiormente interessate dalla presenza delle caulerpe. In particolare Le ricerche di ARPA-Sicilia sono state mirate a: - Definire le aree di studio principalmente interessate dal fenomeno di diffusione delle due alghe aliene; - Caratterizzare da un punto di vista ambientale le aree oggetto d’indagine; - Valutare le pressioni antropiche che insistono lungo le coste delle aree indagate; - Stimare l’influenza che le pressioni antropiche possono esercitare sulla diffusione della Caulerpa; - Indagare l’andamento spazio-temporale della distribuzione di Caulerpa in specifiche aree di indagine. Gli studi condotti da ISPRA hanno puntato a: - Valutare possibili interferenze dell’alga con le attività di pesca, l’intasamento delle reti e la riduzione della pescabilità dell’attrezzo; - Rilevare l’eventuale diversità tra aree con insediamento e prive di insediamento; - Avviare l’introduzione di buone pratiche per evitare che la pesca possa rappresentare un ulteriore vettore di invasioni secondarie attraverso disseminazione dei frammenti e propaguli dell’alga; - Definire comportamenti alieutici nel tempo utili alla mitigazione del potenziale impatto della pesca sulle risorse nelle aree colpite; - Istituire in tutta l’area di studio e, in particolare, nell’arcipelago delle Pelagie, un “Osservatorio delle Specie Aliene” per svolgere attività di monitoraggio sulla diffusione delle specie aliene, al fine di formulare proposte gestionali mirate alla salvaguardia degli ecosistemi e delle attività economiche di pesca. Le indagini realizzate dal CNR-IAMC hanno avuto come obiettivi principali: - Confrontare le caratteristiche dei popolamenti bentonici associati a praterie di Posidonia oceanica della Sicilia meridionale interessate dall’invasione di Caulerpa taxifolia var. distichophylla con quelle di popolamenti associati a posidonieti di località limitrofe non colpite dal fenomeno; - Confrontare la struttura trofica della comunità bentonica associata a matte di Posidonia oceanica in località invase e non invase da alghe aliene del genere Caulerpa della Sicilia meridionale; - Valutare gli effetti dell’invasione di Caulerpa racemosa var. cylindracea sulla struttura e sulla funzione di popolamenti macrobentonici sessili di fondo duro dell’infralitorale