Search

Population abundance, distribution and habitat preference of the Mediterra-nean sympatric seahorses Hippocampus guttulatus and Hippocampus hippocam-pus were investigated in a semi-enclosed sea system (Apulian coast, IonianSea). A total of 242 individuals of seahorses were sighted in the 11 transectssurveyed in summer 2011. Hippocampus guttulatus (n = 225) were 14 timesmore abundant than H. hippocampus (17). The mean abundance of H. guttula-tus for all the pooled sites was 0.018 m 2 (SE 0.003) ranging from a maxi-mum of 0.035 (SE 0.007) to a minimum of 0.008 (SE 0.002). The sizestructure of long-snouted seahorse shows a population ranging from 7 to14 cm (SL) with a peak at 10 cm (TL). Juveniles (96.0 8.0 mm) represent asignificant fraction of the population, accounting more than 21% of the sightedindividuals. In Mar Piccolo, H. guttulatus is able to shelter both in monoto-nous habitats, including the algal beds, and diversified ones, such as the richfilter-feeder communities that colonize hard substrates. By contrast, H. hippo-campus is mainly associated with habitats of low complexity. Today, the MarPiccolo di Taranto is among the most heavily polluted water bodies in SouthItaly, with trace metals, hydrocarbons, pesticides and organic wastes affectingboth biotic and abiotic matrices. However, despite the high level of degrada-tion, the presence of a large mussel farm has avoided the impact of towed fish-ing gears, and eutrophication of water bodies has ensured a high trophic levelthat supports large crustacean populations, potential prey for seahorses.IntroductionWorldwide, seahorse (Hippocampus Rafinesque 1810 spp.)populations and their relatives in the family Syngnathidae(pipefishes, seadragons and pipehorses) are threatened by(i) degradation of their estuarine, seagrass, mangrove andcoral habitats (Olden et al. 2007), (ii) incidental capturein fishing gear (bycatch) (Vincent 1996), and (iii) over-exploitation for use in traditional medicines and in theaquarium trade (Salin et al. 2005). Moreover, seahorseshave life histories, behaviour and ecology that make themparticularly vulnerable to population decline (Foster V Vincent et al. 2011). In addition, seahorses inhabitshallow, coastal areas worldwide, where anthropogenicdisturbances tend to be the most frequent and severe,and represent the main threat to their integrity. The

The macrozoobenthic assemblage from the Karavasta lagoon system, the main wetland of Albania, was studied on soft bottoms and artificial hard substrates. Three different communities were identified: the typical ‘brackish-water community’, an ‘outlet community’ dominated by filter-feeders, and a typical ‘marine community’, inhabiting fine sandy bottoms, where polychaetes are dominant, together with a few species of tunicates and bivalves, which colonize hard substrates. The occurrence of build-ups of the bryozoan Conopeum seurati, settled on the upper portion of long submerged wooden poles, was the main feature of faunistic interest. The faunistic affinity between the zoobenthic assemblage recorded in the hyperhaline lagoon of Karavasta and the assemblages from two Italian lagoons, the brackish Lake of Lesina and the euhaline Lake of Fogliano, was considered according to the different hydrological conditions and the geographical location. Hydrological confinement and salinity were likely to be the leading factors influencing the benthic community composition in the Karavasta wetland area. Therefore, on a vaster spatial scale, the isolation and geographical proximity of the ecosystems and colonizing ability and dispersal changes of the species appear to be the main factors liable to produce faunal variations.

The present study focuses on the reproductive success of transplants of the bath sponge Spongia officinalis Linnaeus, 1759, with the aim of investigating the possibility of restocking this species, one of the most endangered organisms of the Mediterranean sessile zoobenthos. Transplants of S. officinalis, collected from a wild population along the Apulian coasts (Ionian Sea, Italy), have been moved into an area where the species was present in the past. The transplants consisted both of specimens in toto and of fragments of different sizes, obtained after having cut the mother sponge into pieces. All transplanted sponges showed complete cicatrisation of the cut surfaces within a month of the initial manipulation and had a survival rate of 100% throughout the 12 months of the study. From the present investigation, it has emerged that the reproductive effort and the larval release by the transplants do not differ significantly from those shown by the source population. This successful technical approach supports its application as a strategy for restocking the population of this endangered species.

A coastal red coral [Corallium rubrum (L.)] population, whose age structure and demographic parameters have been previously analysed, harbours 10 species of endobiotic sponges. This sponge assemblage differs considerably from that inhabiting other calcareous substrata of the surrounding area, suggesting some selectivity for red coral. The two most common endobiotic species, Spiroxya heteroclita Topsent and Cliona sarai Melone, are described in detail. The percentage of infested coral colonies increases according with colony age, with a sharp increment at four years. An increase in coral colony mortality observed at this age may be related to the increment of endobiotic sponge infestation.

Tethya microstella, T. orphei, T. robusta, and T. seychellensis live in sympatry in a Maldivian coral reef lagoon (Gangehi Island, Ari Atoll). A morphological, morphometric, and electrophoretical study of these species show that their Maldivian populations are well separated morphologically and genetically. The genetic distances and the other data are more consistent with an immigration than with a local speciation hypothesis. Their coexistence may be explained by a differentiation in ecological requirements. The four species inhabit the shallow water biotope of the lagoon among the rubble of dead corals. Our data show that T. orphei and T. seychellensis occupy the upper rubble layer, T. microstella and T. robusta the lower one. This distinction agrees with the different morpho-functional features of the two pairs of species.