Summer biomass of a population of Iridaea cordata (Gigartinaceae,Rhodophyta) from Antarctica

Results of a seasonal study on biomass in an infralittoral population of Iridaea cordata from Terra Nova Bay (Ross Sea, Antarctica) are reported. Thalli were collected during the IX Italian Antarctic Expedition (austral summer 1993–94). The population studied is that living at depths of 4 to 6 m, where the highest density of plants occurred. The highest value of biomass (wet weight 3440 g m^–2) was found at the beginning of summer. In that period 72.5% of biomass was from 128 specimens belonging to weight classes 8 (>16 to 32 g) to 10 (>64 g), corresponding to 13.4% of the population in numbers. Small (<1 g) and medium (1 to 8 g) specimens provided the remaining biomass of 5% and 22.5%, respectively. During the month of January, the number of heavy specimens decreased. At the end of that month biomass reached a minimum of 2225 g m^–2. In February the biomass increased to 3169 g m ^–2, 72% of which was from 120 specimens belonging to weight classes 7 (>8 to 16 g) to 9 (>32 to 64 g), which numerically represented 18.5% of the population. Data showed that biomass depended mainly on the presence of large heavy specimens, even though they were always few in number. Moreover, the occurrence of such large thalli at the beginning of summer suggests that Iridaea cordata continues to grow during the long antarctic winter.     

Taonia lacheana sp. nov. (Dictyotales, Phaeophyta), from the Mediterranean Sea

A new species of the genus Taonia (Dictyotales, Phaeophyta) is described from the Mediterranean Sea. The species is characterized by pseudodichotomous fronds having entire margins and by a pronounced differentiation between the medullary and cortical cells throughout the thallus. Only tetrasporangial plants were found. The species differs from T. atomaria f. ciliata in having differently sized cells in cross section and an entire margin and from T. lennebackerae in both the habit and in the shape of cells in longitudinal section.     

Verosphacela silvae sp. nov. (Onslowiaceae, Phaeophyceae) from the Mediterranean Sea

We describe Verosphacela silvae sp. nov., from the Mediterranean Sea. It consists of horizontal filaments living on the lower face of the red alga Peyssonnelia rubra (Greville) J. Agardh, from which erect filaments up to 1.5 mm high rise and grow upright after passing through the thallus of the supporting species. There are both horizontal and erect filaments growing by apical cells. In the subapical cells, 1–2 longitudinal divisions occur (more frequently in the erect filaments) but no secondary transverse divisions occur. Erect filaments bear lateral propagules on a stalk of one to three (rarely more) cells. Propagules, with neither apical cells nor arms, consist of seven cells. Zoidangia are borne at the apex of erect laterals. The new species differs from V. ebrachia Henry mainly in habit, propagules and zoidangia. In addition, distinct from V. ebrachia, filaments of V. silvae never penetrate between the cuticle and the cell wall of the supporting alga. Moreover, propagules of V. silvae consist of seven cells, whereas those of V. ebrachia consist of 9–13 cells, and zoidangia are terminal on laterals in V. silvae, whereas in V. ebrachia they are sessile on both axes and laterals.     

The benthic algal flora on rocky substrata of the Tremiti Islands (Adriatic Sea)

ABSTRACT

The results of a floristic study of benthic marine macroalgae on rocky substrata from the Tremiti Islands (Adriatic Sea) are presented. The list of taxa at specific and infraspecific level consists of 226 Rhodophyceae, 59 Fucophyceae and 36 Chlorophyceae. Of these 321 taxa, 147 are newly reported from the Tremiti Islands. Data on the reproductive phenology of each species, and comments on some species of particular interest are also given.     

Sulla presenza nell'Italia meridionale di alcune alghe marine bentoniche rare per il Mediterraneo

Abstract

On the occurrence in Southern Italy of some benthic marine algae rare to the Mediterranean Sea. - The Authors report the occurrence along the coast of Southern Italy of the following species that resulted rare to the Mediterranean Sea: Antithamnion piliferum Cormaci et Furnari; Bonnemaisonia asparagoides (Woodward) C. Agardh (tetrasporophyte); Corynophlaea flaccida Kuetzing; Fosliella farinosa (Lamouroux) Howe: of this very common species, the occurrence of thalli with propagules is reported; Hypnea cervicornis J. Agardh; Jania adherens Lamouroux, new to Italy; Mesogloia lanosa P.L. et H.M. Crouan, new to Italy; Pneophyllum confervicolum (Kuetzing) Chamberlain f. minutulum (Foslie) Chamberlain, new to the Mediterranean Sea; Polystrata fosliei (Weber van Bosse) Denizot, new to Italy; Rhodymenia delicatula Dangeard; Spermothamnion johannis G. Feldmann-Mazoyer: of this common species, the occurrence of bisporocysts in monoic gametophytes is reported; Vickersia baccata (J. Agardh) Karsakoff.     

Peroxynitrite and myocardial contractility: in vivo versus in vitro effects

Generation of peroxynitrite (ONOO-) as a result of altered redox balance has been shown to affect cardiac function; however, inconsistencies in the data exist, particularly for myocardial contractility. The hypothesis that the cardiac impact of ONOO- formation depends on its site of generation, intravascular or intramyocardial, was examined. Cardiac contractility was assessed by pressure-volume analysis to delineate vascular versus cardiac changes on direct infusion of ONOO- into the right atria of conscious dogs both with normal cardiac function and in heart failure. Additionally, ONOO- was administered to isolated murine cardiomyocytes to mimic in situ cardiac generation. When infused in vivo, ONOO- had little impact on inotropy but led to systemic arterial dilation, likely as a result of rapid decomposition to NO2- and NO3-. In contrast, infused ONOO- was long lived enough to abolish beta-adrenergic (dobutamine)-stimulated contractility/relaxation, most likely through catecholamine oxidation to aminochrome. When administered to isolated murine cardiomyocytes, ONOO- induced a rapid reduction in sarcomere shortening and whole cell calcium transients, although neither decomposed ONOO- or NaNO2 had any effect. Thus, systemic generation of ONOO- is unlikely to have primary cardiac effects, but may modulate cardiac contractile reserve, via blunted beta-adrenergic stimulation, and vascular tone, as a result of generation of NO2- and NO3-. However, myocyte generation of ONOO- may impair contractile function by directly altering Ca2+ handling. These data demonstrate that the site of generation within the cardiovascular system largely dictates the ability of ONOO- to directly or indirectly modulate cardiac pump function.     

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.     

Stucture and reproduction of Cordylecladia guiryi sp. nov. (Rhodophyta,Rhodymeniales) from the Mediterranean Sea

Abstract

Cordylecladia guiryi sp. nov. is described from the Mediterranean Sea, after a comparison of habit, morphology and reproduction with C. erecta, the only species of the genus. The species is characterized by the small dimension of its axes which arise single from the basal crust and by its habitat, growing epiphytically on Posidonia oceanica Delile leaves. Tetrasporangial and gametangial plants as well as the development of the carposporophyte have been studied in detail. The carpogonial branch is 4-celled and it is formed on a supporting cell that also bears a 3-celled auxiliary branch. Tetrasporangia are cruciately divided. The reproductive details confirm Sparling's view about the great variation existing in the organization of the procarp in members of this order.     

Summer biomass of a population of Phyllophora antarctica (Phyllophoraceae,Rhodophyta) from Antarctica

Results of a study on summer biomass in aninfralittoral population of Phyllophora antarctica A.et E. S. Gepp from Terra Nova Bay (Ross Sea,Antarctica) are reported. The population studied grewat depths of 5 to 12 m. The highest value of biomass(1548 wet g m⁻²) was found at the end of January at6 m depth. Data showed that biomass depended mainly onthe presence or absence of large heavy specimens, eventhough these were always few in number. Moreover, thevery high number of specimens in weight classes 1 (upto 0.03 wet g) and 2 (> 0.03 to 0.06 wet g) recordedfrom December to January showed a relevant productionof new thalli in that period; the decrease of thetotal number of thalli from 8832 counted on 30December to 4384 counted on 10 February, showed someself-thinning in the population; the occurrence ofnumerous thalli belonging to weight classes 3 (>0.06 to 0.125 wet g), 4 (> 0.125 to 0.25 wet g) and5 (> 0.25 to 0.5 wet g) just at the end of December,allows to conclude that P. antarctica continues togrow, although at low rate, during the period ofwinter darkness. Finally, both the low number ofthalli of weight classes 6 (> 0.5 to 1 wet g) and 7(> 1 to 2 wet g) and the absence of thalli of theweight class 8 (> 2 wet g), recorded at the end ofDecember, indicate that most of specimens reachingduring the winter such weight classes (due to theirability to dark growth), died before summer. This revised version was published online in July 2006 with corrections to the Cover Date.