Volume 47, Issue 3

To determine the composition, abundance and horizontal distribution of resting cysts in modern coastal sediments from Scapa Flow, Orkney, Scotland, sediment samples were collected from 12 stations. Twenty-six dinoflagellate cyst types representing eight motile-defined genera and one cyst-defined genus were observed. Four species or species groups dominated the assemblage for the Flow as a whole, Scrippsiella trochoidea , unidentified round brown cysts, Polykrikos schwartzii and Alexandrium tamarense . Total cyst abundance ranged from 37–1524 cysts ml −1 wet sediment. The majority of cysts occurred in the central area of the Flow, where higher densities were observed. Of particular importance is the distribution and abundance of cysts of A. tamarense . Since 1991 there have been annual toxic episodes of paralytic shellfish poisoning, caused by the vegetative stage of A. tamarense , in Scapa Flow, leading to widespread bans on all shellfish activities for months at a time. Cysts of A. tamarense were widely distributed within the Flow and ranged from 0–212 cysts ml −1 wet sediment. The overall widespread distribution and higher abundances of cysts of A. tamarense in the central areas of the Flow indicate potential seedbeds for initiation of future vegetative growth and subsequent outbreaks of paralytic shellfish poisoning.

Forty-two different dinoflagellate cyst types were found in recent sediment samples collected between July 1999–September 2002 from 44 stations along the eastern coast of Russia. This represents the first survey of recent dinoflagellate cysts in Russian marine waters. Forty cysts were identified to the species level, representing 17 genera. The most common cysts were those of ellipsoidal Alexandrium spp., Protoceratium reticulatum, Gonyaulax spp. , Polykrikos kofoidii, P. schwartzii , Protoperidinium americanum, P. minutum , P. conicoides , P. subinerme , P. conicum and Scrippsiella trochoidea . Fifteen of the dinoflagellate species have not previously been recorded as motile cells in Russian marine waters: Alexandrium cf. minutum , Cochlodinium cf. polykrikoides , Diplopsalis cf. lebourae , Fragilidium mexicanum, Gonyaulax elongata, G. membranaceae, Gymnodinium cf. catenatum , Pentapharsodinium dalei , P. tyrrhenicum , Protoperidinium americanum , P . cf. avellanum , Scrippsiella cf. lachrymosa , S . cf. precaria , S . cf. rotunda and Warnowia cf. rosea . Cysts of the potentially toxic species Alexandrium cf. minutum , A . tamarense and Gymnodinium cf. catenatum were also found in this survey. Ellipsoidal Alexandrium tamarense type cysts were widely distributed and dominated many localities in the study area. These data suggest that additional cyst surveys should be conducted in areas of the eastern Russian coastline not yet investigated, and that the potential for paralytic shellfish poisoning toxicity as a result of blooms of toxic species may be more widespread than previously documented.

Many seaweeds produce secondary metabolites that deter herbivory, but intraspecific variation in both the identity and the concentration of chemical defenses has been documented rarely. In order to evaluate the occurrence of chemical variation in the brown seaweed Stypopodium zonale along the Brazilian coast, we investigated the defensive properties of crude extracts and major secondary metabolites found in specimens from two distant locations (Forno inlet, Búzios, southeastern Brazil and Fernando de Noronha archipelago, northeastern Brazil) against herbivory by the crab Pachygrapsus transversus and the sea urchin Lytechinus variegatus . At natural concentrations, the extracts from S. zonale from Búzios and Fernando de Noronha significantly deterred feeding by P. transversus and L. variegatus , although the former was more effective as a defense than the latter. Corroborating these results, the major metabolites atomaric acid, found in individuals from Búzios, and stypoldione, from Fernando de Noronha specimens, also inhibited herbivory, but atomaric acid was more effective as a defense against L. variegatus and P. transversus than stypoldione. The variation between S. zonale from two distant and different geographic locations in Brazil suggests that defensivechemicals from this seaweed are not qualitatively or quantitatively absolute or invariant characteristics of the species, and may represent an ecological specialization to successfully prevent herbivory.

Fatty acid composition was monitored in Caulerpa taxifolia collected from January to December 1998 in the northern Adriatic Sea. Saturated (45.2–73.7%), monounsaturated (10.3–25.9%) and polyunsaturated (16–34.3%) fatty acid proportions varied considerably during the period investigated. The Caulerpa growth cycle proceeded through a) minor changes during the latent and growth recruitment phase in spring, b) a gradual increase in unsaturated fatty acids during maximum growth in the summer/early autumn period and c) an abrupt increase, particularly of polyunsaturated fatty acids, during biomass maintenance and survival as lowering temperatures approached the lethal level. These variations were similar to those found in native algal species of temperate regions. Stimulation of growth and spreading can be partly explained by successful adaptation of C. taxifolia to the seasonality of environmental parameters (primarily temperature).

The chemical composition of the brackish-water green alga Cladophora rivularis was investigated. Seven sterols were identified and the stereochemistry of the most common forms was established. Thirty-eight and 21 compounds were identified in the volatile and polar fractions, respectively. The main lipid classes were isolated and their fatty acid compositions established. The antibacterial, antimycotic and cytotoxic activities of the extracts were investigated. Comparisons were made with previously investigated marine and freshwater Cladophora species. Results obtained give information on the effect of salinity on algal metabolism.

Tetrasporogenesis in Rhodymenia californica var. attenuata is accomplished in four developmental stages. The first stage is represented by a uninucleate tetraspore mother cell sourrounded by an electron transparent cell wall. Dictyosome activity and endoplasmic reticulum are not evident at this stage and starch formation does not occur. Thylakoids are formed from unraveling concentric lamellar bodies. Multiplication of plastids results from fission of the existing organelles. The tetraspore mother cell increases in size and undergoes decussate cruciate division by cleavage infurrowing, resulting in the formation of four tetraspores which represents the second stage of tetraspore development. Also, granular vesicles are formed from the endoplasmic reticulum. The third stage is characterized by the formation of fibrous vacuoles from the fibrous vacuole associated organelles. The fourth developmental stage is represented by maturation of tetraspores and is signaled by the massive production of cored vesicles from hypertrophied dictyosomes and the presence of abundant starch granules. Mature tetraspores are surrounded by a bi-layered wall and the tetrasporangial wall, while unbranched, tubular structures run parallel to the plasmalemma.

Confocal laser scanning microscopy was used to investigate the three-dimensional organisation of the microtubular cytoskeleton of protoplasts isolated from the cortex and medulla of the red alga Palmaria palmata . Immunofluorescence labelling revealed the presence of abundant microtubules in interphase cells. Cortex-derived and medulla-derived protoplasts each exhibited a distinctive arrangement of microtubules. In cortex-derived protoplasts, a continuous network of cytoplasmic microtubules connected the peripheral array to the array which surrounded the single nucleus at the centre of the cell. At telophase, the microtubular cytoskeleton was reorganised into a network apparently involved in cytokinesis. In the multi-nucleate medulla-derived protoplasts, each nucleus, located near the plasma membrane, was surrounded by microtubules. A uniformly arranged cortical array of microtubules was observed in both cortex-derived and medulla-derived protoplasts during interphase and we hypothesise that it likely plays a role in the biogenesis of the cell wall in red algal cells.

The new marine nanoplanktonic diatom, Thalassiosira fryxelliae , is described with light and scanning electron microscopy from material collected in Argentinian coastal waters. T . fryxelliae is a morphologically distinctive species with: 1) cells embedded in irregular gelatinous masses, 2) absence of central, sub-central and scattered strutted processes on the valve surface, 3) one marginal ring of strutted processes with external tubes, 4) one marginal labiate process included in the ring of the strutted processes, 5) areolation pattern variable linear, sublinear, eccentric or irregular. Externally, the marginal strutted processes have double tubes, at least in the distal part, cut distally and with the half-cylinder bent vertically with crenulated distal edges and the labiate process has a simple tube. Internally, the strutted processes are short with four operculate satellite pores and the labiate process is sessile and radially located. Thalassiosira fryxelliae is similar to T . angulata and T . nanolineata in morphology and distribution pattern of the marginal strutted processes and in the location of the labiate process and to T . leptopus and some specimens of T . guillardii and T . pseudonana in lacking one central strutted process.

Uptake rates of dissolved organic nitrogen (DON; urea, alanine and glutamate) by Ulva pertusa were determined using axenic cultures and 15 N isotopic tracers. When urea or alanine was added to N-starved cultures, the incorporation of 15 N into algal tissue was found at all concentrations tested (0.5–40 μM). Maximum uptake rates were 7.92 and 3.00 μmol N g −1 dw h −1 , and half-saturation constants were 25.5 and 27.6 μM for urea and alanine, respectively. These results show that U. pertusa can take up urea and alanine directly without bacterial decomposition to inorganic nitrogen. Therefore, U. pertusa is able to utilize certain species of DON, and has the potential to regulate DON fluxes and transformations in coastal environments.

Up to the present time, Boodleopsis (Udoteaceae, Chlorophyta) has been represented on the Brazilian coast by Boodleopsis pusilla only. This study describes B . vaucherioidea from the southern coast of Rio de Janeiro State, Brazil. Non-fertile plants were collected in April, June and November 2000, and January 2003, and then compared with the holotype from the Colombian Caribbean Sea. Considering field and cultured plants, the Brazilian specimens were identified as B . vaucherioidea , and distinguished from B . pusilla by the upright filaments without constrictions above the forks, and their divaricate branchlets. This is the first record of B . vaucherioidea for the south Atlantic Ocean.

Undaria pinnatifida, a laminarian kelp (Phaeophyta) native to Japan, Korea and northern China, has been introduced recently to the coast of southern California (USA). We present the first record of this invasive species on the Mexican Pacific coast, and show the current southern limit along the Pacific coast of North America. U. pinnatifida was found on September 28th, 2003, growing attached to small rocks on a sandy bottom in the subtidal zone at 12–14 m depth at Todos Santos Islands, in Baja California, Mexico. This population consisted of 15 sporophytes, with an average length of 50 cm and with mature sporophylls. This new finding suggests that the colonization of the Pacific coast of North America by this invasive species is still occurring, and its distributional range is expanding.