Volume 53, Issue 3

We analyzed rocky reef benthic macroalgae on the western coast of the Baja California peninsula, Mexico. To describe the assemblages, we sampled two reefs that are geographically proximate but influenced by different oceanographic conditions, leading to potential differences in factors that could affect the macroalgal assemblage. Using analyses of similarities, we found significant differences between sites and seasons. Additionally, composition changed seasonally, but was not related to depth. Using SIMPER analysis, the species that defined the assemblages at “Arvin”, Tortugas Bay were Macrocystis pyrifera , Sargassum muticum and Plocamium cartilagineum ; in contrast, the key components at “Queen” were Padina caulescens , Polysiphonia johnstonii var. concinna and Dictyota coriacea , showing how oceanographic conditions can influence the biogeographic pattern of macroalgal assemblages along the northwestern coast of Mexico.

Despite a wealth of laboratory experiments describing seagrass growth and competitive interactions with macroalgae under varying nutrient concentrations, there is limited information available from field studies conducted in complex natural environments. We examined ecological change over time in the Saipan Lagoon, Western Pacific Ocean. Here, seagrass ( Halodule uninervis ) canopy cover was quantified monthly at relatively small spatial scales over a 3-year period. Where watershed size and human population were low, there was a significant relationship with seasonal environmental cycles; cooler temperatures correlated with increased drift, red algal abundance and freshwater input increased green algae. Following cyclical macroalgal overgrowth, however, seagrass again became the dominant canopy. Conversely, in the presence of high human population and urbanization, seasonal cycles were absent and a seagrass-to-macroalgal transition was evident. Adjacent to a large watershed with moderate pollution, significant ties were found between seagrass emergence and winter-time disturbance events (large swells), as detached macroalgae that formed during summer months were removed annually. In summary, seagrass systems associated with Saipan Lagoon appear to be hierarchically controlled, following: 1) disturbances, 2) land-based pollution, and 3) seasonal environmental cycles.

Greenhouse experiments were conducted to assess the effects of soil salinity on germination, growth, water status, proline content and mineral accumulation of seedlings of Rhizophora mucronata (Rhizophoraceae). NaCl was added to the soil and salinity was maintained at 0.2, 2.5, 5.1, 7.7, 10.3, 12.6, 15.4, 17.9, 20.5, 23.0 and 25.6 psu. This plant is highly salt tolerant at the germination stage. Growth of seedlings was significantly promoted by low salinity and optimum growth was obtained at 20.5 psu. Moreover, higher salinities inhibited plant growth. Water potential of tissues became significantly more negative with increase in salinity. Proline content in tissues significantly increased as salinity increased. The concentration of Na in tissues increased, whereas K, Ca, N and P content decreased with increase in salinity. We discuss changes in tissues and whole-plant accumulation patterns of other nutrients, as well as possible mechanisms for avoidance of Na toxicity in this plant in response to salinity.

Punctaria tenuissima (Chordariaceae, Phaeophyceae) is reported for the first time from the Azores. Erect thalli were collected on the Island of São Miguel; they were up to 3 cm long, flattened and often twisted. The plurilocular sporangia were formed from surface cells that were quadrate or rectangular in surface view. Unilocular sporangia were not observed in the field. In culture, the plurispores of P. tenuissima developed into Hecatonema -like, tufted, prostrate thalli that formed plurilocular sporangia. The plurispores of the prostrate thalli cultured at 15°C with a long day (LD) photoperiod developed into new prostrate thalli, which in turn formed plurilocular sporangia. This cycle was repeated 5 times, resulting in several generations of reproductive prostrate thalli. When these cultures were cooled to 10°C with a short day (SD) photoperiod, new erect thalli developed from the prostrate thalli resembling the thalli collected in the field. These erect blades produced unilocular and plurilocular sporangia on the same or on different thalli. The plurispores and unispores produced by the erect thalli at 10°C under SD conditions once again developed into new prostrate thalli. This is the first report of unilocular sporangia formed in cultures of P. tenuissima . Sexual reproduction was not observed. The culture conditions, particularly temperature and daylength, appeared to influence the formation of erect blades. The Punctaria -like thalli were produced in 10°C/SD conditions, whilst the Hecatonema -like thalli were produced under 10°–15°C/LD and SD conditions. These results are similar to those reported for P. tenuissima from other locations and suggest the occurrence of both direct and heteromorphic life histories in the Azorean algae.

Symphyocladia lithophila sp. nov. is newly described using both morphological and molecular analyses of samples collected from the southeastern coast of Korea. The new species is characterized by small size, ecorticate thallus, with 8–10 pericentral cells, lacking trichoblasts, and having 5–7 segments of congenital fusions. S. lithophila was observed to be a winter species, producing tetrasporangia from December to February. Plastid-encoded rbc L sequences were determined in four samples of S. lithophila from different locations and 21 samples of four putative relatives, including the most related genus Pterosiphonia . All four Symphyocladia lithophila replicates from three different locations had almost identical rbc L sequences, and interspecific sequence divergences were sufficient to warrant its separation as a natural entity. The phylogeny of the rbc L sequences also indicated monophyly of the genus Symphyocladia , which is separated from the genus Pterosiphonia . The specimens of Pterosiphonia , including the type species P. cloiophylla from its type locality in South Africa, form a monophyletic group.

Preliminary studies on dinoflagellates epiphytic on macrophytes in a bight of Peter the Great Bay, Sea of Japan revealed the presence of two species of the genus Ostreopsis , O. cf. ovata and O. cf . siamensis . Morphometric features, such as the length of the pore plate, and thecal ornamentations were used for species identification. The two species differed from each other in cell size and the length of the pore plate. Cells of O. cf. ovata were smaller in length and width, with a dorsoventral diameter of 36–60 μm and a width of 24–45 μm, in comparison with the cells of O. cf. siamensis , which were 63–78 μm in dorsoventral diameter and 36–54 μm in width. Cells of O. cf. siamensis are slightly flattened in comparison with O. cf. ovata ; the dorsoventral to anteroposterior diameter ratio varied from 1.9 to 2.7 for O. cf. ovata and from 1.8 to 3.5 for O. cf. siamensis . The length of the pore plate in O. cf. ovata (6.3–8.3 μm) is shorter than that in O. cf. siamensis (11–13 μm), while the diameter of the thecal pores in O. cf. ovata and O. cf. siamensis overlapped markedly (0.12–0.25 μm and 0.16–0.20 μm, respectively). The two species were present from August to October at water temperatures of 7–25°C on almost all macrophytes collected. The maximum abundance of Ostreopsis spp. reached 10,970 cells g -1 dry weight in late September at a water temperature of 9°C. This is the first occurrence of the genus Ostreopsis in Russian waters, which are characterized by cold temperatures during the winter season.

Five species of seagrasses and six species of seaweeds in 11 genera were collected from the Gulf of Mannar, on the southeastern coast of India and were screened for antioxidant activity by in vitro methods. Methanolic and water extracts of the seagrass Halophila ovalis had the highest antioxidant activity, with IC 50 values 78.95±1.15 and 85.40±3.40 μg ml -1 (means±SE), respectively, using the NO radical scavenging method. With the H 2 O 2 scavenging method, both methanolic and water extracts of many of the seagrasses and seaweeds had higher antioxidant activity, with the IC 50 values lower than that of the standard tocopherol. Except for vitamin B 3 , the rest of the antioxidant-potent phytoconstituents estimated in these marine organisms were found to be strongly positively correlated with the antioxidant activity.

Aqueous and organic extracts from Dictyopteris membranacea collected from the Tunisian Mediterranean coast were studied for their anti-inflammatory, antioxidant and anti-microbial activities. All extracts had high anti-inflammatory activity in carrageenan-induced rat paw edema assays in Wistar rats, and their effects are comparable to acetylsalicylate lysine (300 mg kg -1 , applied intraperitoneally) used as a reference drug. Dictyopteris membranacea extracts had inhibition percentages in the third hour of the assay of 65% at a dose of 100 mg kg -1 , 51% at a dose of 50 mg kg -1 , and 49% at a dose of 100 mg kg -1 in aqueous, chloroform and ethyl acetate extracts, respectively. Chloroform and ethyl acetate extracts exhibited 2,2-diphenyl-1-picrylhydrazyl radical scavenging with IC 50 values (0.089±0.01 and 0.11±0.02 mg ml -1 , respectively) equivalent to the activity of a powerful antioxidant standard, Trolox (IC 50 =0.09±0.02 mg ml -1 ). These extracts (chloroform and ethyl acetate) had reducing activity, and the total phenol contents were: 84.96 and 60.96 mg gallic acid equivalent per gram dried sample, respectively. Organic extracts had moderate antimicrobial activity (using the disc diffusion method) against three bacteria: Staphylococcus aureus , Staphylococcus epidermidis and Micrococcus luteus , and four species of a fungal genus: Candida albicans , C. krusei , C. dubliniensis and C. kefyr at 10 mg per disc, whereas the aqueous extract exhibited significant antibacterial activity against only Staphylococcus aureus and Listeria monocytogenes .

A sulfated polysaccharide H3-a1 [designated polysaccharide fraction, H3-a1, of Hydroclathrus clathratus (HCP)] was isolated and purified from an edible brown seaweed Hydroclathrus clathratus ; HCP contained about 8.6% protein and a relatively high sulfur content (8.2%). HCP significantly affected the growth of human acute promyelocytic leukemia cells (HL-60), human breast carcinoma (MCF-7) and human hepatocellular carcinoma cancer cell lines. As revealed by flow cytometry, when HCP was co-incubated with HL-60 and MCF-7 cells for 72 h, it induced significant sub-G1 arrest (apoptosis) of these cells. HCP caused G1 phase arrest but did not induce terminal differentiation of these cancer cells. In vivo antitumor tests showed that HCP inhibited tumor growth at doses of 20 and 50 mg kg -1 in tumor-bearing BALB/c (supplied by the Laboratory Animal Services Centre of The Chinese University of Hong Kong) mice, but this effect was not due to an in vivo inhibitory effect on tumorigenesis. Nevertheless, HCP suppressed ascitic Sarcoma 180 tumor growth and prolonged the life span of the tumor-bearing mice by about 30–40%. HCP had no observed toxic side effects; it did not affect blood cells, or body, liver or spleen weights of mice 4, 7 and 10 days after treatment. This sulfated polysaccharide induced increased tumor necrosis factor-alpha (TNF-α) level in mouse serum. It also activated peritoneal macrophages to secrete TNF-α and nitric oxide.

Alkaline cellulases were screened from 54 fungal isolates obtained from mangrove leaves and mangrove wood litters as endophytes and wood litter fungi, respectively. Only three fungal isolates tested positive for alkaline cellulases under plate assay, among which Chaetomium sp. (NIOCC 36) was found to grow in a wide range of pH (between 4 and 12). This alkaline tolerant fungus was further tested for production of alkaline cellulases (β-endoglucanase, β-exoglucanase, β-glucosidase) using agricultural and industrial wastes as substrates in submerged fermentation (SMF) and solid state fermentation (SSF) processes. Cotton seed under SSF conditions had maximum enzyme production at high alkaline pH. Cellulase enzymes produced under alkaline cotton seed SSF conditions at 50°C had higher stability and activity than under non-alkaline conditions (range tested: pH 5, 7, 12). The agricultural and industrial wastes used as carbon sources were economical for commercial production of cellulose. The high specific activity, and stability of cellulases under neutral to alkaline pH and high temperature will be of use in various industrial and biotechnological applications.

I surveyed marine fungi collected from the Mediterranean coast of Egypt. A total of 31 taxa, including 19 ascomycetes and 12 anamorphic fungi, were identified from 100 submerged driftwood samples collected randomly along two sandy beaches. The most frequent fungus was Corollospora maritima . Other common fungi include C. portsaidica , Leptosphaeria oraemaris , Cumulospora marina and Periconia prolifica . Among the 31 taxa identified during this study, 21 are new records for the Mediterranean Sea, bringing the total number of Mediterranean marine fungi to 79. Seven new fungi were recorded during the course of this study, of which two new species of Corollospora and one anamorph have been described, and work is in progress to describe the remaining four. An unknown species of Didymosphaeria is illustrated in this paper, but not formally described because there was insufficient material available for further study of the species.