Volume 51, Issue 5

We examined the ability of vegetative propagules (small buds and branch fragments) of the green alga Codium fragile ssp. tomentosoides to attach and grow on natural substrata in laboratory and field experiments. In the laboratory, the probability of attachment (on coralline algae, mussel shell, smooth and rough rock) was greater for buds than excised apical branches (both ∼4 cm long) over 10 weeks, and greater in weak flow (1.3 cm s -1 ) than static conditions. Probability of attachment differed among substrata in flow (greater on coralline algae than smooth rock) but not static conditions. Attachment strength in flow was greater for buds than fragments (pooled over substrata). Growth was greater for fragments than buds in static conditions, but not in flow. Fragments grew more in static conditions than in flow. In a field experiment, buds were transplanted to three tide pools at different tidal heights on a rocky shore. After eight months, the proportion that attached and attachment strengths of transplants did not differ significantly among pools. However, transplants in the high pool grew less and were discolored and atypically branched compared to those in pools lower on the shore. These findings indicate that vegetative propagation may contribute to the invasive success of Codium fragile .

The physiology and biochemistry of Phaeodactylum tricornutum have been extensively studied, and some aspects of its biology are well known. Phenotypic plasticity is probably one of its most remarkable features. Two basic morphotypes, fusiform and triradiate, can be found in natural liquid environments. Although the transformation from one morphotype to the other has been previously reported, ecological causes and consequences of such transformation remain unknown. Here, we report changes in the relative abundance of the two morphotypes of Phaeodactylum associated with changes in the inorganic carbon system. The relative abundance of the triradiate morphotype increased in cultures grown at either high pH or high dissolved inorganic carbon, and markedly so under subsaturating illumination for growth. At high pH, this increase was strongly correlated with a decrease in the overall culture growth rate. At the individual (cell) level, there was a larger increase in the surface area of the triradiate morphotype (resulting in a higher surface-to-volume ratio) than in the fusiform morph under subsaturating illumination for growth. These results provide new insights into the biology of this diatom, mainly related to the performance (fitness) of the two basic morphotypes under contrasting illumination for growth and different inorganic carbon conditions.

The endocrine-disrupting chemical bisphenol A (BPA) has attracted attention because of its estrogenic activity and its extensive environmental distribution. The objective of this study was to investigate the physiological response of the alga Cyclotella caspia , a dominant species isolated from Futian Nature Mangrove Reserve, Shenzhen, China, to BPA at different concentrations (4, 6, 8, 10 and 12 mg l -1 ). We studied the effects of BPA on biomass, growth rate, chlorophyll (chl) a content, cellular morphology, and superoxide dismutase (SOD) activity of C. caspia . The effective concentration of BPA that inhibited algal growth by 50% at 96 h was 7.96±0.23 mg l -1 . Algal biomass, growth rate and chl a content decreased with increasing BPA concentration. BPA concentrations greater than 6 mg l -1 strongly inhibited cell division, significantly increased cell volume, and caused cellular inclusions to appear. SOD activity increased with the BPA concentration, but decreased with prolonged exposure time, showing a dynamic process from induction to inhibition. Our results provide baseline information for the development of marine ecotoxicology and physiology theories concerning BPA.

Ceramium kondoi is a morphologically variable ceramiaceous red alga that occurs commonly in the northwest Pacific Ocean region and has recently been reported in the United States. Forty-five specimens of C. kondoi from 29 locations in Korea, Japan, Russia, and the USA were examined for DNA sequence variation along the whole plastid-encoded RuBisCO cistron: 1406 bp for rbc L, 103 bp for the spacer, and 387 bp for rbc S. C. kondoi specimens were variable, having up to nine haplotypes, with six found in Korea, southern Japan, far-eastern Russia, and the USA, and three found in northern Japan and far-eastern Russia. The occurrence of the same haplotype on both sides of the North Pacific Ocean provides evidence of recent introduction of the species from the west to the east. Phylogenetic reconstructions revealed the monophyly of C. kondoi and two well-supported lineages: a ‘southern lineage’ that contained specimens from Korea, southern Japan, far-eastern Russia and the USA, and a ‘northern lineage’ that included specimens from northern Japan and far-eastern Russia. The two genetic lineages are morphologically indistinguishable and referred to as cryptic species. The boundary between the two cryptic species is at the Tsugaru Strait, Japan.

Espírito Santo State lies in a region of transition between tropical and subtropical benthic-algal floras; the region is considered to have the richest algal assemblage in the whole of Brazil. Extensive rhodolith beds cover much of the subtidal substratum in this area and host a diverse assemblage of frondose macrophytes. A detailed exploration at several localities has revealed many little-known and previously unreported taxa that are new to the southwestern Atlantic Ocean. In November 2004, the gelatinous rhodophytes Acrosymphyton caribaeum , Dudresnaya crassa , Naccaria corymbosa , Platoma sp. and Predaea feldmannii were discovered on rhodoliths at a depth of 18 m. Morphological and reproductive features of the species are provided here, with emphasis on post-fertilization events. The holotype of Platoma tenuis , originally described from Brazil, was examined and shown to be a species of Predaea . Acrosymphyton caribaeum hosted the epiphyte/endophyte Colaconema ophioglossum , and this also represents a new report from Brazil. This diverse community probably represents an ephemeral spring-summer element of the wider macroalgal flora.

Examination of specimens referable to Champia salicornioides from offshore algal plains in southwest Puerto Rico (Caribbean Sea) resulted in recognition of algae with different branching origins. Plants with branching from the septal regions are referred to a new species, Champia harveyana. Segregation of the new species is supported by 18S and rbc L sequence analyses as well as differences in internal morphologies. In the new species, walls of older portions are reinforced by a proliferation of longitudinal medullary filaments that line the interior of the cortical layer and nodal septa. Additionally, nodal regions in older parts become thickened by a proliferation of cells outside the original cortical layer. A lectotype of Champia salicornioides is designated.

The distribution, abundance and diversity of modern dinoflagellate cyst assemblages were investigated in sediments from the inshore seas of southern Chile (43°08′–54°55′ S) at eight sites from April 2004 to January 2005. A total of 24 cyst types were recorded, of which 12 and five were identified at the species and genus levels, respectively. Dinoflagellate cysts were recorded from all sampling sites, but they differed in total abundance (15–270 cysts ml -1 ) and diversity index (H′ 0.88–2.40). Heterotrophic dinoflagellate cysts assigned to heterotrophic species were the most abundant trophic form, with 418 cysts ml -1 , representing 55% of the total cyst abundance. Cluster analysis based on the abundance of dinoflagellate cyst species indicated that sampling sites were segregated into three groups likely to be related to the proportion of autotrophic vs. heterotrophic species cysts and the total abundance of cysts at each site. Distinctive cyst species composition differences among sampling sites may allow inferences about local nutrient and feeding dynamics within the water column.

Marine epiphytic diatoms in the Antarctic Peninsula have not been studied in detail previously, and information on their distribution and occurrence is scarce. We studied the marine epiphytic diatoms on several species of macroalgae belonging to the Rhodophyta, Phaeophyceae and Chlorophyta. We recorded a total of 50 epiphytic diatoms, with Cocconeis spp., Entopyla australis var. gigantea , Grammatophora arctica , Licmophora antarctica and Pseudogomphonema kamtschaticum the most common taxa. Diatoms appeared to have substratum preferences rather than site preferences. The most frequent hosts for diatom attachment were the rhodophytes Pantoneura plocamioides , Delesseria lancifolia and Georgiella confluens . Phaeophytes were less favourable hosts, and no diatoms were recorded on the chlorophytes.

Growths were found on the surface of Catenella nipae at Patonga, New South Wales, Australia. Morphologically similar growths on C. impudica from Indonesia have been reported as the red algal parasite Catenellocolax leeuwenii . The internal anatomy of the Australian growths showed that they all contained septate fungal hyphae. The hyphae formed spherical clusters that, in larger galls, produced inwardly directed hyphae terminating in spores. It is proposed in this paper that these galls are caused by fungal infection, as is the case in other algae. The lack of sexual structures precludes identification of this fungus to any definite species, although it is probably an ascomycete. Inspection of the type material of C. leeuwenii did not reveal any parasites. The limited description of the parasite of C. impudica , the proposed growths induced by fungi in C. nipae , and the lack of holotype specimens, warrants treating the generic name Catenellocolax with caution until more collections from the type locality can be made.

We investigated chemical constituents and the antifeedant, antibacterial, and antilarval activities of EtOH (ethanol) extracts of the South China Sea seagrass Enhalus acoroides . Eleven pure compounds including four flavonoids and five steroids were obtained. Among these compounds, three flavonoids were antifeedant against second-instar larvae of Spodoptera litura , two flavonoids had antibacterial activity towards several marine bacteria, and one flavonoid showed strong antilarval activity against Bugula neritina larvae. This is the first description of isolation and bioactivity of secondary metabolites from E. acoroides .