Pycnogonida collected monthly from September 2017 to August 2018 in the Portofino Marine Protected Area at 0-5 m depth were studied. A total of 499 specimens were collected, 457 of which were ...identified to species level. These were classified as belonging to 10 species: Achelia echinata*, Ascorhynchus castelli, Neotrygaeus communis*, Tanystylum conirostre*, Anoplodactylus angulatus, A. petiolatus, A. pygmaeus*, A. virescens, Callipallene phantoma and C. tiberi*. For five dominant species (those marked with an asterisk) the annual phenology was outlined. Four hundred and seventeen additional specimens, collected from the same area and depth range mainly during the 1970s and 1980s were identified to species level for completeness of information, leading to the addition of Pycnogonum pusillum and Endeis spinosa.
Two Pinna nobilis populations thriving inside the borders of the Portofino Marine Protected Area (MPA) (Ligurian Sea, western Mediterranean Sea) were monitored before (2012) and after (September ...2018) a dire mass mortality event that, since September 2016, spread through the whole Mediterranean Sea. In Portofino MPA, recorded mortality rates reached values of 91.29% and 43.94% in the two populations. The presence of a Haplosporidium protozoan parasite, considered to be the main cause of the mortality episodes, was confirmed from histological evidence: sporocysts and plasmodia were observed in all the tubules of the digestive glands of the collected specimens. Moreover, a catastrophic storm hit the Ligurian coasts at the end of October 2018, causing considerable damages both below and above the surface; a new survey conducted in November 2018 showed the complete annihilation of the two studied populations, as a probable combination of the continued parasite infections and the mechanical impacts caused by the storm. Finally, in June 2020 the sites were monitored again looking for traces of recovery, but no new specimens were recorded, indicating that P. nobilis became virtually absent from the MPA.
An exceptional assemblage of the sea fan Leptogorgia sarmentosa (Anthozoa: Gorgoniidae) was observed inside the Genoa harbour, which represents one of the major Mediterranean ports. The studied ...assemblage is confined in a shaded portion of a floating dock thriving in extremely shallow water, with specimens even touching the sea surface. It represents the shallowest population of this species and of this genus known worldwide. A total of 188 specimens were observed and measured: the maximum density of 45 specimens m
−2
was reached in the most shaded part of the dock, where the maximum height of colonies (30 cm) was also recorded. Light measurements showed that the illuminance along the dock was comparable to that observed outside the harbour at 20 m depth, where the nearest colonies of L. sarmentosa were recorded for this region. This suggests that high levels of incident light might be putatively interpreted as the limiting factor in the upper bathymetrical distribution of the species. Despite the extremely shallow distribution, however, the population cannot be defined as intertidal as the floating dock avoids exposing the gorgonians to air. The chance to grow far from the silted bottom, but still in a turbid, sciaphilous and nutrient-enriched environment, probably enhanced the settling and growth of the colonies and allowed the formation of a dense and healthy population.
Most works concerning growth and reproduction of Mediterranean sponges have been performed in the oligotrophic western Mediterranean while little is known about sponge dynamics in the North-western ...Adriatic Sea, a basin characterized by low winter temperature and eutrophy. In order to deepen our understanding of sponges in the North Adriatic Sea and verify how its peculiar trophic and physical conditions affect sponge life cycles, temporal trend of sponge cover (%) and reproductive timing of
Chondrosia reniformis
and
Tedania
(
Tedania
)
anhelans
were studied over a 1-year period looking for a possible relation with variations of temperature or food availability. In
C. reniformis,
although little variations of sponge cover were evidenced around the year, the number of individuals and their size increase during spring. Asexual reproduction
,
via drop-like propagules, mainly occurs in spring and summer, while sexual reproduction is characterized by a maximum number of oocytes in August.
T. anhelans
progressively grows from spring to summer and develops propagules on its surface that reach their maximum size in July. In autumn, the sponge undergoes a process of progressive shrinkage and almost disappears in winter when temperature reaches 7–8°C. Larvae occur during summer. In the North Adriatic Sea sponges have larger sizes, higher density and a wider period of oocytes production compared with the same species from the Mediterranean Sea, suggesting these differences could be due to high food availability characterizing the eutrophic Adriatic basin. On the contrary, the sharp water temperature variations and the very low winter temperature, 5–6°C lower than what has been reported for the Mediterranean Sea, regulate temporal variations in abundance and cause the disappearance of thermophile species during winter.
During spring 2017, starting from 12 May, exceptional strandings of the purple snail Janthina pallida were recorded in the Ligurian Sea and along the western coast of Sardinia Island, under the ...effect of southern winds. The strandings continued for 3 days, until 15 May, when the winds shifted to the northern quadrant and the specimens were drifted back offshore. Such extensive strandings have never been previously reported in the scientific literature, either along the Mediterranean shores or elsewhere. Thanks to citizens' help, it was possible to create a map of the strandings and obtain a gross estimate of the number of beached gastropods. The densities of the stranded animals reached an overall average of 801 ± 215 specimens m
−2
(with peaks of over 2000 shells and rafts m
−2
densely packed with hydrozoan Velella velella sails), corresponding to an average biomass of about 1.5 kg m
−2
. The size-frequency distribution of the shell heights showed a bi-modal trend, as is usual in the case of sequential hermaphroditism: almost all the specimens fitting the first mode (11 mm) showed a raft without eggs (males), while all the specimens belonging to the largest mode (23 mm) had rafts with settled egg cases (females). The general trend of the sea currents in the North-western Mediterranean Basin explains the spatial distribution of the strandings following 3 days of constant southern moderate breeze (up to 28 km h
−1
). The presence of such huge J. pallida banks in the Ligurian Sea is stochastic, probably linked to an Atlantic population entering through the Gibraltar Strait, as evidenced by the simultaneous presence of the buoy barnacle, Dosima fascicularis, a circumtropical species recorded here for the second time in the Mediterranean Sea.
Exploiting high density features of wireless sensor networks represents a challenging issue. In this context, anonymous, asynchronous and randomly distributed sensors are considered along with few ...devices, called actors, which are more powerful than sensors in terms of energy and transmission capabilities. The paper proposes a new distributed training protocol for coarse-grain localization purposes in high density environments. The aim is to auto-organize the sensors with respect to a virtual infrastructure centered at actors and constituted of concentric rings divided into sectors. Analytical study as well as experiments on the proposed protocol are provided. The obtained results show under which theoretical and practical settings the training process can be performed in a fast and high quality way with respect to the granularity of the required localization and the energy consumption.
Benthic suspension feeders in shallow waters develop in relation to the food availability and the variation of physical parameters giving rise to complex communities that act as a control factor on ...the plankton biomass. The aim of the work is to establish the role of the hydrozoan
Eudendrium racemosum
in the energy transfer from the plankton to the benthos in marine food chains of the North Adriatic Sea. This study highlighted that the hydroid biomass changed over time in relation to temperature and irradiance, and the highest abundance was observed during summer with about 400,000 polyps m
−2
(about 19 g C m
−2
). The population suffered an evident summer decrease in relation to a peak of abundance of its predator, the nudibranch
Cratena peregrina
, whose adult specimens were able to eat up to 500 polyps day
−1
and reached an abundance of 10 individuals m
−2
. The gut content analysis revealed that the hydroid diet was based on larvae of other benthic animals, especially bivalves and that the amount of ingested preys changed during the year with a peak in summer when it was estimated an average predation rate of 13.7 mg C m
−2
day
−1
. In July, bivalves represented over 60 % of the captured items and about 18 mg C m
−2
day
−1
. Values of biomass of
E. racemosum
are the highest ever recorded in the Mediterranean Sea, probably supported by the eutrophic conditions of the North Adriatic Sea. Moreover, our data suggest that settling bivalves provide the greater part of the energetic demand of
E. racemosum
.
In the last few decades, macrobenthic community structures and their species abundances have shown significant changes in the Mediterranean Sea, whose causes were attributed to anthropogenic ...activities and to global warming effects. The Mediterranean sponges have shown a peculiar sensitivity to these changes: the populations of some species showed significant decreases, while others, more thermophilous, increased. Therefore, sponges may be a good proxy for evaluating the effects of environmental changes. Thanks to the observations conducted by Sarà about 55 years ago, a comparative analysis of the sponge populations present within two semi-submerged caves in the Ligurian Sea was possible. The two sponge assemblages re-studied in 2016 showed an increase in terms of specific richness and a significant change in their structural aspects, since the three-dimensional growth forms were mostly replaced by two-dimensional ones, a process observed also in other littoral communities. Consequently, the sponge communities inside the semi-submerged caves may be considered poorly resilient: the massive sponges were hit by the positive thermal anomalies occurring in the Ligurian Sea in the last decade and were replaced by encrusting forms, within a possible phase of cave recolonisation.
Consecutive underwater observations carried out in shallow waters of Pontetto (Ligurian Sea) from June to the end of November 2013 revealed the presence of purple areas on the white surface of the ...asconoid calcareous sponge Clathina coriacea . Histological and ultrastructural investigations performed on the purple areas of the sponge showed the occurrence of a network of hyphae of an indeterminate fungus permeating the sponge tissues and presumably responsible for the unusual colour of the sponge. The hyphae, varying in size and morphology according to their location in the sponge body, are visible on the outermost sponge surface and, after crossing the mesohyl, penetrate inwards into the choanodermal layer, being mainly located along the apical border of the choanocytes. The occurrence of undamaged flagella and microvillar fringes, which are the organelles characterising the choanocyte cells, is consistent with a normal functionality of the sponge tissues, notwithstanding the presence of the fungal hyphae. The fungus develops only in summer because it disappears concomitantly with the approach of autumn. This feature is coherent with the consideration that the sponge acts as a suitable substrate for the developing fungus, which, in turn, does not interfere with the sponge filter-feeding activity.
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