Volume 53, Issue 2

Relatively little is known about the causes of species distribution within macroalgal blooms occurring on or over soft substrata. We examine the roles of aerial exposure and desiccation in determining elevational patterns of two dominant bloom-forming ulvoid algae, Ulva lactuca and Ulvaria obscura , on the northeastern Pacific coast. These species were stressed with constant desiccation time, desiccation to a constant water potential, and desiccation to a fixed water loss. As a measure of health, we examined net photosynthesis by oxygen evolution or photosynthetic yield via pulse amplitude modulated fluorometry. By all measures, Ulva was physiologically superior in the intertidal zone. Under constant exposure, it desiccated more slowly than Ulvaria . When desiccated to a constant dryness, Ulva better maintained photosynthetic parameters. These observations are consistent with Ulva 's usual dominance over Ulvaria in intertidal macroalgal blooms. Given these and other observed differences between the two species, natural resource managers should not regard the two as ecologically equivalent, even though they have similar functional forms.

This study, performed over the years 1999–2003, analyzed the species composition, spatial distribution and ecological aspects of macroalgal assemblages on Atol das Rocas reef, located 266 km off northeastern Brazil. It is the sole atoll in the South Atlantic and is almost completely built of coralline algae. Forty-seven new occurrences of macroalgae were recorded. Adding these to the previous studies, 143 taxa are now known for the local marine flora, with the Rhodophyta as the dominant group. New finds were mainly on the fore reef and in reef pools. The inner habitats (the reef flat, internal ridge and inner pools) harbored fewer macroalgal species than the outer habitats (the reef front, reef crest crevices and outer pools). Inner habitats are subject to prolonged desiccation and solar irradiation stress together with abrupt changes in temperature and salinity controlled by the water oscillations of the mesotidal regime within the atoll; the outer habitats are less affected by these short temporal impacts and are mainly governed by oceanic forcing. Atol das Rocas harbors some species unknown in other Brazilian waters, but these are common in Caribbean reef waters.

The red alga Gracilaria lemaneiformis was cultured under different CO 2 and phosphorus conditions for 16 days, and its growth, photosynthesis and uptake of nitrate and phosphate were examined in order to establish the longer-term impacts of elevated CO 2 and phosphorus supplies on this economically important seaweed. Enrichment with either CO 2 or phosphorus in culture markedly increased the growth of G. lemaneiformis compared to the control. Light-saturated photosynthetic rate was enhanced significantly by phosphorus enrichment, but hardly affected by the elevation of CO 2 when G. lemaneiformis was grown under low phosphorus conditions. High phosphorus stimulated photosynthetic inorganic carbon utilization and nitrogen uptake. Under low phosphorus conditions, the thalli grown at the high level of CO 2 had a lower carbon utilization capacity and a higher nitrogen uptake rate compared to those grown under ambient CO 2 . Reversed results were found when the algae were grown under high phosphorus conditions. Hence, available phosphorus may regulate inorganic carbon utilization of G. lemaneiformis grown at different CO 2 levels, and growth reflected a balance between carbon and nutrient metabolism.

Morphological examination of sympatrically growing specimens referable to Champia parvula collected as seagrass epiphytes has resulted in the recognition of a new Champia species. The new species bears resemblance to type specimens of C. parvula , differing mainly in branching pattern (opposite vs. typically alternate) and branch origin (between the septa vs. nodal region), number of axes arising from holdfasts (4–7 vs. 1 or more), and monoecious vs. dioecious gametophytes. On the basis of analyses of small ribosomal subunit and rubisco large subunit ( rbc L) gene sequences, the new species was distinct from its sympatric partner. The new species clades most closely with C. vieillardii , C. compressa , and what is tentatively referred to as C. parvula from Puerto Rico. Furthermore, rbc L sequence comparison between C. vieillardii and C. compressa supports their recognition as distinct species.

Laurencia marilzae is recorded for the first time from the western Atlantic Ocean; it was found in Laje de Santos Marine State Park, São Paulo, southeastern Brazil. The specimens were collected in the rocky subtidal zone from 7 to 15 m depth. The most distinctive characteristic of this species is the presence of corps en cerise in all cells of the thallus, including cortex, medulla, and trichoblasts. The phylogenetic position of the species was inferred by analysis of the chloroplast-encoded rbc L gene sequences from 43 taxa, using two other rhodomelacean taxa and two members of the Ceramiaceae as outgroups. Within the Laurencia assemblage, L. marilzae from Brazil and from the Canary Islands (type locality) formed a distinctive lineage sister to all other Laurencia species analyzed. Male plants are described for the first time. This study expands the geographical distribution of L. marilzae to the western Atlantic Ocean.

The brown macroalga Cladostephus spongiosus is reported for the first time from the central Pacific coast of the Baja California Peninsula. Thalli ranged from 3 to 20 cm in length, with the shortest occurring in January (winter) and the tallest in June (summer). Reproductive individuals were present in all seasons except autumn, when mean seawater temperatures reached 20.4°C. The species was found from the mid-intertidal to 6 m depth in the subtidal zone. The most common species growing with C. spongiosus were the brown algae Dictyopteris spp., Dictyota coriacea , and Padina caulescens , the red alga Polysiphonia johnstonii var. concinna and the surf-grass Phyllospadix torreyi . A detailed description of the vegetative and reproductive structures is provided. Its limited local distribution suggests a recent introduction to this region.

We conducted a first study of Pseudo-nitzschia species and their morphological variability in the main shellfish farming and harvesting areas of Greece between 2004 and 2008. Water samples were collected and preserved, and unialgal cultures of Pseudo-nitzschia species were established. Both preserved and culture material of 12 taxa were examined by transmission electron microscopy and included P. delicatissima , P. fraudulenta , P. galaxiae , P. mannii , P. multistriata , P. pseudodelicatissima , P. pungens , P. subfraudulenta , one morphospecies similar to P. dolorosa and one strain corresponding to a P. delicatissima -like morphotype (all new records for Greek coastal waters); in addition, we found two previously recorded species, viz., P. calliantha and P. multiseries . We present ultrastructural descriptions and morphometric data for the local populations studied.

Cymodocea nodosa , a marine angiosperm, an ecosystem engineer in the Mediterranean Sea and the Northwest Atlantic Ocean; however, as in other seagrasses meadows worldwide, the swards are actually declining due to increasing human pressures. Hence, we have developed an effective propagation methodology that provides C. nodosa seedlings for seagrass meadow restoration and conservation. This method consists of: i) germination of wild-collected seeds under hyposaline conditions, ii) acclimation of germinated seedling in tanks (1.6 m 3 ) until there are two shoots per seedling (∼ 30 days), and iii) transplantation of acclimated seedlings to the field in dense groups. Our field outplants withstood herbivore activity and physical disturbance during the winter season, and propagated vegetatively, resulting in the spread and establishment of a new patch that has persisted for nine months.

Our finding of extensive off-shore meadows of Penicillus capitatus in the Canary Islands is the first direct observation of this species off the eastern Atlantic islands. Populations form scattered patches between 20 and 27 m depths, leading to denser meadows between 28 and 50 m depths. Total population coverage is ca 11.16 ha. Plant morphology, cover and density changed through the year. In September, well-developed individuals were dominant whereas the Espera -phase was dominant in January and March. The highest mean cover and density values were 75.42% cover and 1245 well-developed individuals m -2 , respectively. Specimens reach only 6 cm in height, which is shorter than individuals from the Mediterranean Sea and the Western Atlantic, and they often grow intermixed with species of Caulerpa and Halophila decipiens . It is difficult to determine whether this is a recent introduction, because the species may have been overlooked in the past. Nevertheless, the extensive meadows found in La Palma may be related to recent increases in sea water temperature, and the tropicalization of the marine flora and fauna of the Canary Islands detected during the past decade.

We assessed genetic polymorphism of a bi-allelic anonymous DNA locus in otherwise highly homogeneous Turbinaria ornata populations in French Polynesia, Hawaii, Solomon, Wallis and La Réunion Islands. Large heterozygote deficiencies occurred in almost all populations, which may be related to possible self-fertilisation and short dispersal distance of zygotes. There was a high genetic differentiation among samples (F st =0.5269***) and this was correlated with a gradient of hydrodynamic conditions prevailing on French Polynesian coral reefs. This correlation is tentatively associated with balancing selection acting on, or on the vicinity of, this anonymous DNA locus.

No abstract available