Variability at different spatial scales of a coralligenous assemblage at Giannutri Island (Tuscan Archipelago,northwest Mediterranean)

This study was carried out on the rocky cliffs of Giannutri Island (Tyrrhenian Sea, Italy) to test the hypothesis that coralligenous assemblages are consistent within the bathymetric range considered (25–35 m depth) over three different spatial scales (1000 m, 100 m and 10 m). A multi-factorial sampling design was used to assess patterns of vertical distribution in the studied area. Data on the percent cover of algae and invertebrates were collected at three depths (25, 30 and 35 m) using a photographic method, and percentage cover was obtained using a visual method. Analysis of the results using ANOVA indicated that the distribution and abundance of algae and some invertebrates of the sublittoral assemblages are clearly heterogeneous. Algae, sponges and bryozoans showed significant variability in distribution and abundance at different depths, but this variability was not consistent amongst transects. Ascidians did not show any variability, while the abundance of anthozoans differed significantly amongst transects. We concluded that heterogeneity in the distribution and abundance of the taxa analysed is related to the smallest spatial scale investigated (10's of m). Some of the possible causes of the observed variability are discussed.     

Elevated seawater temperature causes a microbial shift on crustose coralline algae with implications for the recruitment of coral larvae

Crustose coralline algae (CCA) are key reef-building primary producers that are known to induce the metamorphosis and recruitment of many species of coral larvae. Reef biofilms (particularly microorganisms associated with CCA) are also important as settlement cues for a variety of marine invertebrates, including corals. If rising sea surface temperatures (SSTs) affect CCA and/or their associated biofilms, this may in turn affect recruitment on coral reefs. Herein, we report that the CCA Neogoniolithon fosliei, and its associated microbial communities do not tolerate SSTs of 32 °C, only 2–4 °C above the mean maximum annual SST. After 7 days at 32 °C, the CCA exhibited clear signs of stress, including bleaching, a reduction in maximum quantum yield (F_v/F_m) and a large shift in microbial community structure. This shift at 32 °C involved an increase in Bacteroidetes and a reduction in Alphaproteobacteria, including the loss of the primary strain (with high-sequence similarity to a described coral symbiont). A recovery in F_v/F_m was observed in CCA exposed to 31 °C following 7 days of recovery (at 27 °C); however, CCA exposed to 32 °C did not recover during this time as evidenced by the rapid growth of endolithic green algae. A 50% reduction in the ability of N. fosliei to induce coral larval metamorphosis at 32 °C accompanied the changes in microbiology, pigmentation and photophysiology of the CCA. This is the first experimental evidence to demonstrate how thermal stress influences microbial associations on CCA with subsequent downstream impacts on coral recruitment, which is critical for reef regeneration and recovery from climate-related mortality events.     

Shallow-buried Pleistocene Madrepora-dominated coral mounds on a muddy continental slope, Tuscan Archipelago, NE Tyrrhenian Sea

Subfossil azoxanthellate deep-sea coral mounds occur at 355–410 m on the continental slope of the NE Tyrrhenian Sea between Gorgona and Capraia islands, Tuscan Archipelago. These low-relief patch reefs are at present buried by a thin muddy drape. Their age is latest Pleistocene. The colonial scleractinian Madrepora oculata is the major frame builder, in association with the solitary coral Desmophyllum dianthus and the colonial coral Lophelia pertusa. These NE Tyrrhenian Madrepora-dominated coral mounds represent one of the few known Mediterranean examples of deep-coral colonization of a muddy, low-gradient continental slope.     

Discovery of the mineral brucite (magnesium hydroxide) in the tropical calcifying alga Polystrata dura (Peyssonneliales,Rhodophyta)

Red algae of the family Peyssonneliaceae typically form thin crusts impregnated with aragonite. Here, we report the first discovery of brucite in a thick red algal crust (~1 cm) formed by the peyssonnelioid species Polystrata dura from Papua New Guinea. Cells of P. dura were found to be infilled by the magnesium‐rich mineral brucite [Mg(OH)₂]; minor amounts of magnesite and calcite were also detected. We propose that cell infill may be associated with the development of thick (> ~5 mm) calcified red algal crusts, integral components of tropical biotic reefs. If brucite infill within the P. dura crust enhances resistance to dissolution similarly to crustose coralline algae that infill with dolomite, then these crusts would be more resilient to future ocean acidification than crusts without infill.     

Molecular survey of morphological subspecies reveals new mitochondrial lineages in Podarcis muralis (Squamata: Lacertidae) from the Tuscan Archipelago (Italy)

Recent analyses of molecular markers have significantly revised the traditional taxonomy of Podarcis species (Squamata: Lacertidae), leading to critically reconsider the taxonomic value of several subspecies described only on morphological bases. In fact, lizards often exhibit high morphological plasticity both at the intra‐specific and the intra‐population level, especially on islands, where phenotypic divergences are mainly due to local adaptation, rather than to evolutionary differentiation. The Common wall lizard Podarcis muralis exhibits high morphological variability in biometry, pholidosis values and colour pattern. Molecular analyses have confirmed the key role played by the Italian Peninsula as a multi‐glacial refuge for P. muralis, pointing out the lack of congruence between mitochondrial lineages and the four peninsular subspecies currently recognized. Here, we analyse a portion of the protein‐encoding cytochrome b gene in the seven subspecies described for the Tuscan Archipelago (Italy), in order to test whether the mitochondrial haplotypes match the morphologically based taxonomy proposed for Common wall lizard. We also compare our haplotypes with all the others from the Italian Peninsula to investigate the presence of unique genetic lineages in insular populations. Our results do not agree completely with the subspecific division based on morphology. In particular, the phylogenetic analyses show that at least four subspecies are characterized by very similar haplotypes and fall into the same monophyletic clade, whereas the other three subspecies are closer to peninsular populations from central Italy. From these results, we conclude that at least some subspecies could be better regarded as simple eco‐phenotypes; in addition, we provide an explanation for the distinctiveness of exclusive lineages found in the archipelago, which constituted a refuge for this species during last glacial periods.     

On three interesting marine red algae (Ceramiales,Rhodophyta) from the Mediterranean Sea

Abstract

Observations on three interesting Ceramiales from the Mediterranean Sea are reported; Ceramium incospicuum Zanardini, Polysiphonia setacea Hollenberg and Rodriguezella pinnata (Kützing) Schmitz ex Falkenberg. The male reproductive structures on the genus Rodriguezella are described for the first time.     

Seasonal variations of microphytoplankton assemblages and environmental variables in the coastal zone of Bozcaada Island in the Aegean Sea (NE Mediterranean Sea)

Seasonal changes in the microphytoplankton assemblages were examined in the coastal zone of Bozcaada Island with regard to some major physical and chemical variables. Samples were collected from May 2000 to December 2001 at four stations. A total of 108 dinoflagellates, 102 diatoms, 1 chrysophycean, 3 dictyochophycean, and 1 prasinophycean species were identified and quantified during the study period. Diatoms and dinoflagellates were the most important in terms of species number and abundance. The maximum values of total microphytoplankton were observed at 0.5 m depth (46.2 × 10³ cells l⁻¹ at st. 3) in May as this was the month when the diatom Pseudo-nitzschia pungens bloomed. Chlorophyll (chl) a concentration ranged between 0.08 (August) and 0.78 μg l⁻¹ (February). May was another important month in which chlorophyll a increased (0.41–0.47 μg l⁻¹). Species diversity values (H′_log2) ranged from 1.66 bits (June, 20 m) to 4.11 bits (November, 0.5 m). The increase was attributed to a more balanced distribution of abundance among species. The amounts of nitrate + nitrite (0.6−3.7 μg-at N l⁻¹), phosphate (0.2−0.6 μg-at P l⁻¹) and silicate (0.7−2.5 μg-at Si l⁻¹) were recorded on each sampling occasion. Nutrient concentrations and chl a values of the research area were found to be poorer than those of the many other coastal areas in the northeastern Mediterranean. The mean atomic ratio of nitrogen to phosphorus varied from 1.3 (June) to 12.9 (February). This ratio was lower than the Redfield ratio of 16 for ocean phytoplankton, and phytoplankton was potentially limited by nitrogen for most of the months. The result of this study confirms and emphasizes the oligotrophic nature of the eastern Mediterranean.     

Morphology and taxonomy of some rare chlorococcalean algae (Chlorophyta)

The morphologies of 15 rare chlorococcalean algae, i.e. three species of the Characiaceae [Hydrianum crassiapex Korshikov, H. viride (Scherffel) H. Ettl, Characiellopsis skujae (Fott) Komárek], four taxa of the genus Pediastrum Meyen [Pediastrum privum (Printz) E. Hegewald, P. duplex Meyen var. rugulosum Raciborski, P. angulosum (Ehrenberg) ex Meneghini, Pediastrum biradiatum Meyen], a radiococcalean alga Phacomyxa sphagnicola Skuja, Pseudodictyosphaerium fluviatile (Hindák) Hindák from the Dictyosphaeriaceae, three representatives of the family Oocystaceae (Amphikrikos minutissimus Korshikov, Gloeotaenium loitlesbergianum Hansgirg, Chlorolobion obtusum Korshikov) and three species of the genus Scenedesmus Meyen (S. ginzbergeri Kammerer, S. incrassatulus Bohlin, S. parisiensis Deflandre), are documented by drawings and micrographs and their taxonomy is discussed. Of these, Hydrianum viride, Pediastrum duplex var. rugulosum, Scenedesmus ginzbergeri and S. parisiensis are recorded for the first time in Slovakia. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

Quantitative and qualitative variability of epiphytic algae on one Apiaceae (<Emphasis Type="Italic">Apium nodiflorum</Emphasis> L.) in a karstic river (Southeast of France)

Spatial distribution of the firmly attached epiphytic algae was investigated directly on the leaves of one Apiaceae (Apium nodiflorum L.) commonly found in chalky Mediterranean rivers, at two sampling dates (summer and autumn). The composition and structure of the epiphytic communities of the samples were determined at different levels: along the leaves, on both their sides and within each leaflet (n = 13). Forty-eight leaflets from four randomly selected plants were cut along the longitudinal and vertical axes so as to define 16 microhabitats located on the edge, the centre and the vein. Only a few species of algae were found to be constantly present whatever the sampling date, and dominated all microzones (n = 768). Their presence seemed to depend, rather, on the architectural structure of the plant. The other algae represented the major part of the epiphytic community and were only occasionally present. Those were more subject to temporal and environmental variations and less specific of the substrate. The epiphytes showed considerable spatial heterogeneity within their microhabitats, with an evident preference for the centre and the edge of the leaves, whereas two inhospitable spaces were the vein and apex. On the other hand, when the study was performed at a larger scale (along the leaf), the epiphytic populations of the youngest leaves (near the surface) and the eldest ones (close to the sediments) were homogenous, hence suggesting that other factors, independent from the physiology of the plant, may have an impact on epiphytic distribution.     

Phycochromes b and d: their occurrence in some phycoerythrocyanin-containing blue-green algae (cyanobacteria)

Abstract
Phycochromes b and d, two types of photoreversibly photochromic pigments previously extracted from the blue-green alga Tolypothrix distorta , which contains phycoerythrocyanin, have now been found in three Anabaena strains also containing phycoerythrocyanin. Tests for the presence of phycochromes b and d in a number of blue-green algae lacking phycoerythrocyanin have been negative. The possibility that phycochrome b-type absorbance changes are due to changes in the α-subunit of phycoerythrocyanin is discussed.     

Morphological and genetic differences in ecologically distinct populations of Petrosia (Porifera, Demospongiae)

The taxonomic status of two sponge tnorphotypes living sympatrically in Mediterranean caves and usually ascribed to Petrosia ficiformis was elucidated on the basis of morphological, morphometric and genetic features. The two morphotypes, spherical and cylindrical, showed differences in the shape and size of spicules and in the morphology of the aquiferous system. Electrophoretic analyses demonstrated that the two morphotypes are reproductively independent and so they should be considered as distinct biological species. The spicular features allow attribution of the cylindrical morphotype to P.ficiformis and the spherical one to P. clavata. For these two species parasympatric speciation is proposed.     

The presence of the potentially toxic genera Ostreopsis and Coolia (Dinophyceae) in the North Aegean Sea, Greece

The examination of macrophyte, water and sediment samples, collected at depths less than 1.5 m from 50 different sites along the North Aegean coasts, has revealed, for the first time in Greek coastal waters, the presence of two Ostreopsis species (O. ovata and O. cf. siamensis) and Coolia monotis in the majority of the sampling sites (94% and 100%, respectively). Other epiphytic dinoflagellates of the genera Prorocentrum and Amphidinium and diatoms were accompanying species in this epiphytic community. Morphometric features, plate formula and thecal ornamentation were used for species identification. O. ovata cells were smaller in dorsoventral (DV) diameter and width (W) (26.18–61.88 μm and 13.09–47.60 μm, respectively) in comparison with O. cf. siamensis (35.70–65.45 μm and 23.80–49.98 μm, respectively). In contrast, the anterioposterior (AP) diameter of O. cf. siamensis was smaller (14.28–26.18 μm) resulting in DV/AP ≈ 3, whereas the above ratio for O. ovata was less than 2 (AP ranging between 14.28–35.70 μm). Moreover, the theca of O. ovata cells was ornamented with scattered pores, which fluctuated in a wider range (0.07–0.32 μm) than those of O. cf. siamensis (0.23–0.29 μm). Coolia monotis cells were almost round with average DV diameter 26.88 μm, AP 25.66 μm and width 26.76 μm. Small and large cells were recorded in both field and culture populations of Ostreopsis spp. and C. monotis, while hyaline cysts were observed for O. ovata. The presence of O. ovata and O. cf. siamensis exhibited a clear seasonal pattern dominating (maximum abundance up to 4.05 × 10⁵ cells gr⁻¹ fwm) the period from midsummer to late autumn in years 2003 and 2004, while C. monotis was found also in winter and spring months.     

Taxonomy and new bacterial symbioses of gutless marine Tubificidae (Annelida, Oligochaeta) from the Island of Elba (Italy)

In shallow sublittoral sediments of the north-west coast of the Island of Elba, Italy, a new gutless marine oligochaete, Olavius ilvae n. sp., was found together with a congeneric but not closely related species, O. algarvensis Giere et al., 1998. In diagnostic features of the genital organs, the new species differs from other Olavius species in having bipartite atria and very long, often folded spermathecae, but lacking penial chaetae. The Elba form of O. algarvensis has some structural differences from the original type described from the Algarve coast (Portugal). The two species from Elba share characteristics not previously reported for gutless oligochaetes: the lumen of the body cavity is unusually constricted and often filled with chloragocytes, and the symbiotic bacteria are often enclosed in vacuoles of the epidermal cells. Regarding the bacterial ultrastructure, the species share three similar morphotypes as symbionts; additionally, in O. algarvensis a rare fourth type was found. The divergence of the symbioses in O. algarvensis, and the coincidence in structural and bacteria-symbiotic features between the two taxonomically different, but syntopic host species at Elba are discussed.     

A model for the prediction of harmful algae blooms in the Vietnamese upwelling area

Satellite pictures and in situ observations indicate strong phytoplankton blooms including harmful algae blooms (HABs) during southwest (SW) summer monsoon in the Vietnamese upwelling area. In this period, nutrients are provided by coastal upwelling and by the very high river runoff from the Mekong River. During SW monsoon, in general two circulation patterns exist which allow the prediction of advection and diffusion of HAB patches. A Lagrangian HAB model that is driven by a circulation model and applied to HABs in Vietnamese waters is presented. Advection which is the most complicated part in modelling transport of passive substances is validated with a Lagrangian sediment trap experiment. The model produces realistic results compared to in situ observations and satellite images and might be used for real time forecast in the future.     

Bacterial communities of some brown and red algae from Peter the Great Bay, the Sea of Japan

The structure of microbial communities of brown algae, red algae, and of the red alga Gracilaria verrucosa, healthy and affected with thallus rot, were comparatively investigated; 61 strains of heterotrophic bacteria were isolated and characterized. Most of them were identified to the genus level, some Vibrio spp., to the species level according to their phenotypic properties and the fatty acid composition of cellular lipids. The composition of the microflora of two species of brown algae was different. In Chordaria flagelliphormis, Pseudomonas spp. prevailed, and in Desmarestia viridis, Bacillus spp. The composition of the microflora of two red algae, G. verrucosa and Camphylaephora hyphaeoides, differed mainly in the ratio of prevailing groups of bacteria. The most abundant were bacteria of the CFB cluster and pseudoalteromonads. In addition, the following bacteria were found on the surface of the algae: Sulfitobacter spp., Halomonas spp., Acinetobacter sp., Planococcus sp., Arthrobacter sp., and Agromyces sp. From tissues of the affected G. verrucosa, only vibrios were isolated, both agarolytic and nonagarolytic. The existence of specific bacterial communities characteristic of different species of algae is suggested and the relation of Vibrio sp. to the pathological process in the tissues of G. verrucosa is supposed.     

Biogeography of the family Acartiidae (Calanoida) in the Ponto-Mediterranean Province

In the Ponto-Mediterranean Province, the geographical distribution of 19 species plus 1 variety belonging to the family Acartiidae has been studied. The study utilised cartographic techniques of terrestrial biogeography and the entire Province was subdivided in 1375 squares. The geographic distributions obtained derived from data published during the last 126 years. The first result was that about 3/4 of the area considered has never been sampled, and only about 8% of the entire area has been repeatedly sampled (at least seasonally). Long time-series of sampling are known only from very few sites. The species considered belong to three genera. Species distributions are discontinuous either in space or in time. Three species are endemic. The historical analysis suggests that four species arrived in the Province recently (two of them are Lessepsian migrants; the others have been introduced by human activities). Two species appear to have crossed the Suez Canal from the Mediterranean to the Red Sea (anti-Lessepsian migration). Two species are considered to be ante-Lessepsian (they were tropical species present in the Mediterranean before the Suez Canal opening). The doubtful presence of two species in the Mediterranean is discussed. At the present time, it seems that the distribution of many species is rapidly changing, probably as a consequence of the anthropogenic influence on communication between areas of the Province, and supported by the ability of Acartiidae to cross geographic barriers, mainly as resting stages.