Volume 43, Issue 1

The lepidochronological technique was used for estimating leaf and rhizome production and for detecting past flowerings of the seagrass Posidonia oceanica of the Adriatic Sea. Samples were collected during 1997 at shallow stands (6.5–8 m depth) at Otranto (Southern Adriatic Sea) and S. Domino (Tremiti Archipelago, Central Adriatic Sea). Leaf production was estimated for the current year at Otranto and for a total of four years (the current and three previous years) at S. Domino based on the conservation of leaf sheaths. Other dynamic features (i. e. leaf formation rate, rhizome elongation and production, and flowering) were estimated for a total of 12 years (the current year and 11 previous years) both at Otranto and S. Domino. Leaf production was 574 g DW m −2 year −1 at Otranto and varied from 509 to 587 g DW m −2 year −1 at S. Domino. Rhizome elongation varied from 0.5 to 1.3 cm year −1 at Otranto and from 0.5 to 0.8 cm year −1 at S. Domino, while rhizome production ranged from 13 to 70 g DW m −2 year −1 at Otranto and from 13 to 40 g DW m −2 year −1 at S. Domino. A significantly lower leaf formation rate was observed at Otranto in 1996, while this parameter did not show significant differences among years at S. Domino. Rhizome elongation and production differed among years at both sites, the two more recent years (1996−1997) accounting for lower values. The data concerning leaf production at Otranto and S. Domino meadows were comparable, whereas differences between sites were observed both in the leaf formation rate and in the rhizome growth. No flowerings were observed at Otranto, while a single floral stalk deriving from a flowering which occurred in autumn 1994, was recorded from the shoots taken at S. Domino. This suggests a low frequency of sexual reproduction of P. oceanica along the Italian coasts of the Adriatic Sea. Finally, we discuss the advantages and technical constraints undergone in the use of lepidochronology. This technique, in fact, was very suitable for estimating the annual variation of the leaf formation rate, rhizome elongation and production, whereas it showed a different efficiency in the estimation of the leaf production of previous years, due to the ‘status’ of the plant and the general features of the bed.

A total of forty-three taxa were studied and described. The taxa belong to three orders, thirteen families and twenty two genera. Eighteen genera are new records for the country, as follows: Aphanothece, Aphanocapsa, Merismopedia, Gloeocapsa, Chroococcus, Entophysalis, Chlorogloea, Stanieria, Myxosarcina, Pleurocapsa, Pseudanabaena, Jaaginema, Geitlerinema, Porphyrosiphon, Spirulina, Leptolyngbya, Oscillatoria and Homoeothrix . Twelve species were found in distinctly different habitats from those from which the original type species were collected and described: Aphanocapsa cf. muscicola, Gloeocapsa cf. atrata, G. cf. arenaria, G. cf. punctata, Chroococcus cf. helveticus, C. cf. minor, C. cf. polyedriformis, Myxosarcina cf. concinna , cf. Jaaginema pseudogeminatum, Phormidium cf. priestley, P. cf. puteale and Homoeothrix cf. gracilis. One new combination is proposed [ Stanieria minima (Geitl.) Silva et Pienaar].

Six taxa belonging to the genus Hyella are reported from southern Africa. Samples were collected at thirteen locations; twelve in South Africa and one in Mozambique. Four of the taxa were identified to species level. Three of the species were new records for South Africa viz; Hyella balani Born. et Flah., H. immanis Al-Thukair et Golubić and H. inconstans Al-Thukair et Golubić. Comparison between taxa and the morphological variability of certain features used in the taxonomy of the genus are presented and discussed.

During the period February–June 1996, dinoflagellate cysts were sampled and examined from surface sediments from two different estuaries and three different offshore sites around Mangalore, SW India. Forty-three different types of cysts were recorded in the sediment, of which 38 cysts belonged to the orders Gonyaulacales, Gymnodinales and Peridiniales. Five cyst types could not be identified. Five types of cysts recorded belonged to the potentially toxic genera of Alexandrium Halim emend. Balech and Gymnodinium Stein. The toxic species Gymnodinium catenatum Graham was studied, for the first time, in Indian waters. The cyst flora from SW India is compared to earlier studies on cyst biodiversity and biogeography from the tropics. To our knowledge this is the first study of dinoflagellate cysts in recent coastal sediments from Indian waters.

The compendium of literature citations for Caulerpa racemosa (Forsskål) J. Agardh in the Mediterranean Sea, together with available fresh and preserved material from both known and new localities, were critically examined. This analysis suggests that three distinct taxa of C. racemosa co-exist in the Mediterranean Sea. (i) C. racemosa var. turbinata — uvifera , known since 1926 and 1931 in Tunisia and in the Levantine basin (ii) var. lamourouxii f. requienii , known since the 1950s in the Levantine basin and (iii) an invasive variety which has been quickly spreading, since the early 1990s, throughout most of the Mediterranean Sea (Balearic Islands, France, Western and Southern Italy, Sardinia, Sicily, Greece, Crete, Turkey, Cyprus, Libya and Lampedusa Island, off Tunisia). The last variety differs mainly from the two first varieties by its upright axes with clavate, more or less inflated branchlets, which are uncrowded and radially to distichously disposed. Within the C. racemosa complex, several taxa are known to bear uncrowded, radially and/or distichously arranged branchlets. Among them, C. racemosa var. occidentalis , a tropical taxon widely distributed throughout the tropical seas, appears to be closest to the invasive Mediterranean variety of C. racemosa . Various criteria (taxonomy, kinetics of spread, tendancy to pullulate) suggest that C. racemosa aff. var. occidentalis could be a taxon recently introduced to the Mediterranean Sea.

This is the first study of dinoflagellate cysts in recent coastal sediments from the Swedish west coast. Sediments from 19 sites were investigated. Fifty-four types of cysts were encountered, of these 40 were identified to species level, representing 13 genera. The most common species were those of Lingulodinium polyedrum , Protoceratium reticulatum , Scrippsiella trochoidea , Pentapharsodinium dalei and Gonyaulax cf. spinifera . Cysts of the potentially toxic species Alexandrium minutum and Alexandrium tamarense were widely distributed as well as Gymnodinium nolleri , the non-toxic G. catenatum -like microreticulate cyst found in Northern Europe. Nine of the species found in this survey have not previously been reported from Sweden: Diplopelta parva , D. symmetrica , Diplopsalopsis latipeltata , Diplopsalis lebourae , Protoperidinium americanum , P. avellana , P. divaricatum , P. nudum and P. stellatum .

A demographic study of Cystoseira humilis Kützing present in a tidepool situated on the rocky shore south of Livorno (Ligurian Sea) was carried out. In order to assess density, growth, reproduction, mortality and biomass of the population, the plants, present in three permanent marked squares which had been randomly chosen, were tagged and monitored over three years. The results suggest that the C. humilis population displayed periods characterized by high mortality and low recruitment alternating with periods characterized by low mortality and high recruitment. During the first year of the study the greatest abundance and growth of plants was recorded in spring, while a population decline was observed in the autumn-winter period. New plants appeared between October and April. Density variations were linked to seasonal fluctuations in recruitment and mortality. The seasonal trend of biomass was related to changes in density and plant height. In the second year there was a marked decline in the entire population of C. humilis due partly to absence of recruitment and partly to the high mortality rate during the winter-spring period affecting adult and juvenile plants. This high mortality coincided with an appreciable decrease both in frond length and stem number of the surviving plants, resulting in a marked decrease in biomass. In the third year the resulting availability of substratum facilitated recruitment. The development of reproductive structures showed a seasonal trend throughout the three years of the study. The greatest frequency of reproductive individuals occurred in July, while in January only sterile plants were found.

Fatty acid and lipid composition of different parts of the lamina of the brown alga Laminaria japonica have been examined. Significant differences were found in the amount of polyunsaturated fatty acids (PUFAs) of n-3 and n-6 series as well as in the content of the oleic acid in the lower, middle and upper parts of algal blades. The lower parts of the lamina were rich in n-6 PUFAs, while upper parts were rich in n-3 PUFAs. The highest content of oleic acid as well as that of neutral lipids was found in the middle of the fronds. Phospholipids concentrated mostly in lower parts of the blades, while glycolipids concentrated in the upper zones of the lamina. Examination of the glycolipid composition showed the presence of monogalactosyldiacylglycerol, digalactosyldiacylglycerol and sulphoquinovosyldiacylglycerol. The main phospholipids proved to be phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylhydroxyethylglycine. The relationships between these compounds varied in different parts of the lamina.

From February 1997 to January 1998 the phytoplankton community was studied from five sampling stations located along the longitudinal axis of the estuary of Urdaibai, northern Spain. Amongst the dinoflagellates, Peridinium foliaceum (Stein) Biecheler, Peridinium quinquecorne Abé, Protoperidinium achromaticum (Levander) Balech and Heterocapsa pygmaea Loeblich, Schmidt et Sherley were found to be the most abundant and recurrent species. In this paper, light and epifluorescence micrographs (Calcofluor M2R stained) with measurements, bibliographic references and some remarks on the morphology of these species are given. Seasonal and spatial patterns of distribution in relation to some hydrological parameters (temperature, salinity and nutrients) are also reported. Protoperidinium achromaticum and Heterocapsa pygmaea are identified for the first time in the estuary of Urdaibai.