Volume 51, Issue 4

By October 2007, a total of 31 alien marine macrophytic species had been recorded on Greek coasts. Following a critical review of these findings, these species were classified as established (9 species), casual (8 species) and debatable (14 species). There were also 23 species found in the Greek marine flora that are excluded from the list of alien macroalgae. Brief remarks are provided for the debatable species. Based on the distribution of the alien species, four are considered as invasive, although their impact on the native vegetation has not yet been documented. A trend analysis revealed that most alien species (65% of current total) were found in the period 1971–2007. Shipping contributes to most alien macroalgal immigration (48%), followed by progressive immigration via the Suez Canal (33%), while aquaculture plays a minor role (16%), unlike the western Mediterranean Sea where aquaculture accounts for 73% of the macrophyte introductions.

Eelgrass ( Zostera marina ) in open-coast northeastern Pacific estuaries is primarily intertidal, yet little research has been done on the natural factors controlling its upper intertidal growth limits. This two-year study in the Yaquina Estuary (Newport, Oregon, USA) evaluated the effects of two factors (erosion and macroalgal accumulations) on populations of eelgrass. Six study sites were located on steep (n=3) and shallow (n=3) intertidal slopes. At each site, triplicate plots (9 m 2 ) were placed at five tidal elevations. In the plots, we counted shoots monthly into three categories: vegetative, reproductive, or seedling. Canopy height, blade width, blades per shoot, macroalgal biomass, and an index of erosion were also measured. Yaquina Estuary eelgrass behaves as a perennial in the lower intertidal zone and as an annual in the upper intertidal zone. In the transition between the low and high intertidal zones, there are both perennial (in patches) and annual forms. We suggest that aerial desiccation, macroalgae, and erosion play a role in controlling intertidal eelgrass and that these factors operate in an acute rather than a chronic manner.

In a recent review of the seagrass genus Halophila in Japan, eight taxa including four new species were listed: (i) H. decipiens , (ii) H. minor , (iii) H. major , (iv) H. ovalis , (v) H. mikii , (vi) H. nipponica , (vii) H. okinawensis , and (viii) H. gaudichaudii . In this study, the specific concept of Halophila in Japan as well as some other geographic areas was re-assessed by a combination of nuclear ribosomal ITS1, 5.8S rDNA, and ITS2 sequence analyses and morphological examinations of both recently collected materials and available type collections. The results confirm the distinctness of the Australian endemic species H. australis and the putative pan-tropical taxon H. decipiens ; but also demonstrate conspecificity of: (i) H. minor and H. ovalis ; (ii) H. major and H. mikii ; and (iii) H. nipponica , H. okinawensis and H. gaudichaudii . As an outcome of this study, we recommend restricting the list of Halophila representatives in Japan to the following four species: (i) H. decipiens , (ii) H. major , (iii) H. ovalis , and (iv) H. nipponica . In addition, we predict the possibility of H. major occurring further south than currently recorded.

Of the six genera of seagrasses recorded in India, four were present throughout a 1-year study period at a station off Hare Island, Tuticorin (8°45′ N, 78°12′ E), in the Gulf of Mannar region. Phytochemical analysis of these seagrass extracts revealed the presence of pharmaceutically potent secondary metabolites and appreciable quantities of primary and some secondary metabolites.

We studied growth and photosynthetic response of a shallow-water population of the invasive alga Caulerpa racemosa var. cylindracea off the Island of Ischia (Gulf of Naples, Italy). The effects of temperature on relative growth rate (RGR), light-saturated photosynthetic rate (P max ), dark respiration rate (R d ) and optimal quantum yield (F v /F m ) were assessed for thalli collected in two seasons (early winter and early summer). While temperatures higher than 22°C stressed early winter thalli, as reflected in the decrease in growth rates and optimal quantum yields, both increased with temperature in early summer plants. A difference between the two seasonal samples also occurred in the high-temperature sensitivity of respiration rates, which was enhanced in early winter plants. As changes in a number of the traits considered occur in advance of seasonal minima and maxima, C. racemosa var. cylindracea may behave as a season anticipator. The contribution of observed patterns to the colonization success of the alga is discussed.

We studied (1) the dynamics of colonization by epilithic algae on mechanically damaged colonies of the coral Porites lutea , (2) the dynamics of algal colonization on dead coral fragments (coral pebbles), (3) and regeneration rates of the damaged corals under a broad range of natural light conditions on the fringing reef of Sesoko Island (Okinawa, Japan). After 1 month (of the experiment), 26 algal species occupied damaged coral areas with a projected areal cover of 1–7%. Colonizers were mainly diatoms, Cyanobacteria, filamentous green, brown and red algae. During this period, the algal settlers were not an impediment to coral polyp recovery. The recovery rate of damaged coral tissue was highest after the first month, amounting to approximately 0.15 mm day -1 under bright light (70–90% of incident surface photosynthetically active radiation, PAR 0 ), 0.14 mm day -1 under moderate light (20–30% PAR 0 ) and 0.07 mm day -1 under low light (2–5% PAR 0 ). After 3 months, 58 algal species had settled onto lesions and 43 species onto coral pebbles. Projected areal cover of the algae was 30–90%. After the second month of the experiment, the recovery rates of corals declined sharply to 0.02–0.04 mm day -1 . Under high and moderate light intensities, the measured parameters were similar (with the exception of the number of algal settlers). Under low light, the number, the density of algal settlers and the regeneration rate of polyps on damaged corals were significantly reduced. The algal turf community was formed under light intensities from 20% to 90% PAR 0 , but was not formed under low light.

Toxicity, morphology and distribution patterns of three bloom-forming species of the diatom genus Pseudo-nitzschia (potential producers of the neurotoxin domoic acid and causative organisms of amnesic shellfish poisoning) from Peter the Great Bay in the northwestern Sea of Japan are presented. Pseudo-nitzschia calliantha , P. multistriata and P. multiseries bloomed in Peter the Great Bay in the fall, with abundances exceeding 10 6 cells l -1 . This is the first report of toxicity in P. multiseries from Russian waters. Domoic acid was found in stationary-phase (days 20–35) cultures of P. multiseries isolated from Peter the Great Bay at concentrations varying between 180 and 5390 ng ml -1 or 2 to 21 pg cell -1 , which is in the range reported for other isolates of P. multiseries . The Russian isolate had an increasing ability to produce domoic acid over time in culture rather than the usual trend of decreasing toxicity. No domoic acid was detected (<2 ng ml -1 ) in cultures of P. calliantha and P. multistriata from the same locality. The Russian isolate of P. multiseries produced gametes when mated with the Canadian strains of the opposite mating type, but they never developed into zygotes, auxospores or large initial cells. This suggests that there might be “cryptic” species within P. multiseries . However, a comparison of molecular and morphometric data between the Russian and Canadian strains showed that they indeed belong to the same species.

Ceramium periconicum sp. nov. is described from Baja California Sur, Mexico based on the developmental morphology of vegetative and reproductive plants. The new species is characterized by 4–5 periaxial cells, three cortical initials per periaxial cell (a third of which are produced by vertical division and situated between adjacent periaxial cells), absence of basipetal cortical filaments, and by projecting tetrahedral tetrasporangia in seriate series in an abaxial row. Thalli are less than 3 mm tall and occur in dense tufts. C. periconicum differs from most incompletely corticated Ceramium species in that each periaxial cell divides to produce three cortical initials. Within the genus, three cortical initials per periaxial cell have been reported in C. codii and C. reptans . C. periconicum differs from these species in that two cortical initials are directed acropetally and the third is directed laterally, having been cut off vertically from the periaxial cell and maturing without further divisions between the two adjacent periaxial cells. C. periconicum is also distinguishable from other Ceramium species, such as C. australe , C. clarionense , C. macilentum , C. shepherdii , C. caudatum , C. mazatlanense , and C. personatum by the absence of basipetal cortical filaments and by the sequential production of tetrasporangia from the abaxial sides of fertile axes.

Aqueous extracts from 12 species of Hong Kong seaweeds were screened for their antiproliferative potential on HL-60 and MCF-7 cell lines. Eight seaweeds exhibited selective antiproliferative activity on HL-60 cells, while 10 species possessed some effect on MCF-7 cell line. Two brown seaweeds, Hydroclathrus clathratus and Padina arborescenos , had a higher inhibitory effect on the growth of both cancer cell lines than the others and were less toxic to normal cells. The extract of H. clathratus (Hy) caused morphological alteration of MCF-7 cells when they were treated at the beginning of incubation. Some polysaccharide fractions isolated and purified from Hy had antiproliferative activity on both HL-60 and MCF-7 cell lines. Furthermore, all of these fractions, including the crude extract, had varying degrees of antioxidant activity. In vivo antitumor tests using Sarcoma 180 tumor-bearing BALB/c mice showed that the fraction H3-a from H. clathratus had the best effect in suppressing tumor growth in the treated mice.

Metal concentrations and quantities were determined monthly in different fractions of the submerged angiosperm Ruppia maritima in Monolimni Lagoon, Aegean Sea. Concentrations were the highest in the roots, suggesting that the sediment-to-root pathway is a principal uptake route of metals. Most metals were equally distributed between rhizomes plus stems and leaves; Fe accumulated greatly in the rhizomes plus stems, whereas Cu occurred mostly in the leaves. Positive correlations were found between metal concentrations in different plant parts, suggesting metal translocation. Most metal concentrations in the different parts declined during the growing season. Iron and Cd accumulation was found to be associated with temperature, which strongly influences the plant growth; additionally, Fe and Cd concentrations in plant tissues were negatively correlated with leaf, rhizome plus stem biomass. Copper concentrations in the roots showed a converse monthly pattern. No metal concentration in plant fractions was positively correlated with concentrations in the water or sediments. Metal quantities (μg m -2 ) stored in the plant generally increased 2- to 4-fold during the growing season. Evidence that return to sediments is a major fate of these quantities is provided by the seasonal pattern in sediment metal concentrations.

Arthrobotrys mangrovispora sp. nov. (fungi) isolated from decaying submerged wood in mangroves of Hong Kong is described and illustrated. The species closely resembles A. scaphoides and A. microscaphoides , but is distinguished by its conidial shape and size and septum number. Conidia vary in shape; they are broadly turbinate to elongate-fusoid, range from 25–(38.9)–50×12– (17.3)–24 μm, and possess 0–3 septa. The proportions of conidia with 0, 1, 2 or 3 septa are 6%, 23.5%, 50% and 20.5%, respectively. The new species forms adhesive network trapping devices. Phylogenetic analyses of nuclear and protein-coding DNA sequences (28S, ITS and a combined ITS+β-tubulin dataset) indicate that the new taxon should be assigned to Arthrobotrys .