Volume 64, Issue 1

Phosphorus is a key macronutrient in macroalgal physiology, including carbohydrate anabolism. To determine the effects of phosphorus on different physiological parameters, we cultivated Ulva fasciata specimens from distinct localities (upwelling and non-upwelling sites) in the presence of different phosphate concentrations (0, 2, and 4 µM PO43−${\text{PO}}_{4}^{3-}$). After 15 days, growth rates were similar (approx. 12% day −1 ) and carbohydrate contents had increased in individuals from both sites. In individuals from the upwelling site, carbohydrate contents were high in all treatments (71% dry mass), whereas non-upwelling site individuals cultivated under the highest phosphate concentration showed the lowest carbohydrate content (46% DM). Nevertheless, we observed higher rates of phosphorus uptake in individuals from the non-upwelling site cultivated under the highest phosphate concentration, indicating a stress response to elevated nutrient concentrations. Individuals from both sites cultivated with phosphate maintained healthy photosystems over the experimental period ( F v / F m  = 0.788), whereas those cultivated in the absence of phosphate showed evidence of photosystem impairment, as indicated by a progressive decline in maximum quantum yield. Altogether, our results indicate that site origin and phosphate concentration influence the carbohydrate content in U. fasciata and that individuals from sites with broad environmental variation, such as upwelling events, can show higher productivity.

Caffeine is present in coastal environments worldwide and there is a need to assess its impact on marine organisms. Here, we exposed two species of ecologically important marine macroalgae ( Chondrus crispus and Codium fragile subsp. fragile ) to a suite of caffeine concentrations and measured their response. Caffeine concentrations of 10–100 ng L −1 had no significant effect on the growth rate or photosynthetic efficiency of either algae. Extremely high concentrations (100–200 mg L −1 ), which may occur acutely, produced sublethal effects for both species and mortality in C. fragile subsp . fragile. Our results highlight the need to understand how caffeine impacts marine species.

Three new non-geniculate coralline algal species from South Africa are described that were passing under the misapplied name, Spongites yendoi . Based on plastid encoded DNA sequences from psb A and rbc L markers, these species belong in the subfamily Chamberlainoideae. The DNA sequences, supported by the morpho-anatomical character of tetrasporangial conceptacle roof development, placed all three species in the genus Chamberlainium and not Pneophyllum , the only other genus in Chamberlainoideae. In addition to the diagnostic DNA sequences,  Chamberlainium capense sp. nov . , C. glebosum sp. nov. and Chamberlainium occidentale sp. nov. may be distinguished by a combination of habit, habitat, geographic distribution, and several morpho-anatomical features. Biogeographically all three species are found in the Benguela Marine Province of South Africa, with C. occidentale being the most widespread. Chamberlainium glebosum also has a wide, but disjunct distribution and  C. capense is another South African endemic non-geniculate coralline, whose range is restricted to a 43 km stretch of coastline. Thus far, DNA sequences from type specimens of non-geniculate corallines show that only those species whose type localities are from South Africa are correctly applied; all other non-geniculate coralline names are likely misapplied in South Africa.

Algal diversity in aquatic environments can help assess the health status of ecosystems, provide information about invasions of new species and inform species diversity changes according to environmental conditions. An algal diversity survey (2016–19) of Nador Lagoon (northern Morocco) revealed the presence for the first time of the brown alga Cystoseira aurantia . Since 2015 this alga has been found in high abundance in the northwestern part of the lagoon, mainly around Attalayoun and Nador City. The thalli of larger specimens reached 60 cm in length, and all plants present were free-floating. The species was collected from the water surface to depths not exceeding 2 cm. Floating patches were usually found suspended above sandy and muddy substrates. Increased abundance of this species in the lagoon corresponds with new physico-chemical conditions and ecological parameters, principally resulting from increased water ventilation and improved water quality since 2012. The new communities of C. aurantia may offer a novel resource for the lagoon but high abundance could pose future threats to attached vegetation such as seagrasses and benthic algae by shading and the accumulation of organic detritus. Attention is drawn to taxonomic issues involving C. aurantia .

In this work, we identified non-crustose invasive ( Codium fragile subsp. fragile ) and native Codium spp. ( Codium tomentosum and Codium vermilara ) in the central Cantabrian Sea using DNA barcoding (tufA and rbcL genes). We designed a new FCO tuf A genetic marker for identifying Codium spp. in fresh and herbarium material. The tufA and rbcL sequences revealed three different single haplotypes for each of the species and a lack of intraspecific genetic diversity. The FCO tuf A genetic marker revealed one new haplotype of C. fragile within the native region (South Korea), suggesting the possibility of higher genetic diversity in the donor region of this invasive species.

The genus Opephora currently contains 37 species and 27 infraspecific taxa. However, the existing literature reveals a wide morphological diversity and the need to establish defining characters to circumscribe the genus as a cohesive and, perhaps, monophyletic group. The type material of Opephora pacifica , the generitype, is analysed. We emend the description of both the species and the genus, the latter also based on published light and scanning electron microscopy observations of closely related species. After review of the available literature, we determined that currently only two species can be ascribed with certainty to the genus Opephora : O. pacifica and O. marina . Based on available literature, it is highly likely that O. fragilarioides also belongs to this genus. We present a table with all known species and infraspecific taxa and make comments regarding their recent transfer to other genera, their current accepted nomenclature, and the genus to which they should probably be ascribed pending the collection of further information.

Unicellular algae have evolved to express many forms of high-affinity phosphate transporters, and homologs of these proteins are broadly distributed in yeast, fungi, higher plants, and vertebrates. In this report, an effort has been made to characterize such a transporter gene, StPHO , in the marine diatom Skeletonema tropicum . The primers used for polymerase chain reaction were designed by referring to a homologous gene in a prasinophyte, and the full-length (1692 bp) cDNA of StPHO was then cloned and sequenced. Sequence alignments and secondary structure prediction indicated that StPHO is a gene that encodes a type III Na + /Pi cotransporter (SLC20 family). To study the function of StPHO , specific concentrations of inorganic phosphate (Pi) were used to alter the physiological status of S. tropicum . In each treatment, samples were collected for the measurements of StPHO mRNA, [PO 4 3− ], cell abundance, the maximal photochemical efficiency of photosystem II ( F v / F m ), and alkaline phosphatase activity (APA). The results indicated that the ambient [PO 4 3− ] strongly affected the population growth and related physiological parameters of S. tropicum . The transcription of StPHO was fully repressed when the [PO 4 3− ] was greater than 1 μM but increased approximately 100-fold when the ambient [PO 4 3− ] decreased to 0.02 μM. Within this [PO 4 3− ] range, the regression equations are Y  = −0.6644 X  + 0.9034 and Y  = −0.5908 X  + 0.8054 for Pi-starved and Pi-limited treatments, respectively. This trend of gene expression suggested that StPHO plays an important role in the uptake of [PO 4 3− ], and StPHO may serve as a useful molecular biomarker for Pi-stressed diatom populations in marine ecosystems.