A simple method to produce fragment seedstock for aquaculture of Pterocladiella capillacea (Gelidiales, Rhodophyta)

Raw material of gelidioid red algae yielding high-quality agar has been in short supply due to overharvesting, but in situ farming of gelidioids has not been practical due to their slow growth. To produce vegetative seedstock of a cosmopolitan species, Pterocladiella capillacea, we investigated the number and length of regenerated branches arising from sectioned fragments during 3 weeks of laboratory culture at 10, 15, 20, and 25°C. All sectioned fragments formed axis-like branches mostly from the upper cut edge and stolon-like branches mostly from the lower cut edge, showing a high capacity of regeneration and intrinsic bipolarity. At 20°C, the number of regenerated branches increased to 2.74 ± 1.29 on the upper cut edge and 4.26 ± 2.66 on the lower cut edge. Our study reveals that the use of fragments bearing regenerated branches as seedstock can be a simple method to initiate fast propagation for mass cultivation in the sea or outdoor tank.

Fast climatic changes place an endemic Canary Island macroalga at extinction risk

Global warming and ultraviolet radiation (UVR) affect marine organisms worldwide. However, we still lack knowledge about the consequences of these environmental changes to range-restricted macroalgae species, such as Gelidium canariense, a habitat-forming endemic of the Canary Islands. The aim of this study is to provide useful data for analyzing the conservation status of this endemic species. To do this, (1) we compared distributional data from 1987 with the data collected in 2008 and 2019 along the northern coast of Tenerife; (2) we assessed the variation in macroalgae assemblages dominated by G. canariense over the last decade on this same cost; and (3) we explored the correlation of these results with the actual trends of sea surface temperature (SST), air temperature at 2 m above the sea surface (T2m), UVR, and downward solar radiation (DSR). The results showed significant changes in the distribution of G. canariense in the last 30 years at Tenerife. More than 90% of its populations have declined. The endemic macroalgae have been replaced by the globally distributed species Pterocladiella capillacea at nearly all the sites studied. The cover of G. canariense and Gelidium arbuscula decreased significantly with increasing SST and T2m. Additionally, G. canariense is negatively related to the rise in UVR. These results highlight the vulnerability of both species of Gelidium to global warming and UVR, but especially of G. canariense. The drastic decline of this species reveals the need to upgrade its conservation status and implement protection measures to reduce the damage that predicted global change scenario may have to their relict populations.

Culturable Fungal Community of Pterocladiella capillacea in Keelung, Taiwan: Effects of Surface Sterilization Method and Isolation Medium

Fungi associated with macroalgae are less known when compared with those on wood in the marine environment. In this study, we assessed the diversity of fungi associated with the red alga Pterocladiella capillacea at Chao-Jin Park, Keelung, Taiwan. Algal segments of healthy and dead thalli were washed/sterilized with different solutions (sterile artificial seawater, 70% ethanol, and 4% sodium hypochlorite), plated on three different media (glucose-yeast extract-peptone seawater agar (GYPS), potato dextrose seawater agar (PDAS), and artificial seawater agar (SA)), and isolated as pure cultures. Identification was mainly based on BLAST search analysis of the internal transcribed spacers of rDNA (ITS). The highest isolation frequency (no. of segment with fungi/total no. of segment × 100) was in dead thalli (61.23%), thalli washed with seawater (88.38%), and thalli plated on GYPS (62.10%). A total of 3187 isolates were cultured, representing 129 taxa (in 67 genera); the higher species richness was isolated from healthy thalli (119 species), thalli washed with seawater (111 species), and on GYPS (112 species). Ascomycota (Eurotiales, Hypocreales, Capnodiales, Pleosporales, Xylariales) dominated the fungal community in P. capillacea with many basidiomycetous yeasts and few Mucoromycota. Aspergillus, Cladosporium, Penicillium (Ascomycota), and Rhodosporidium (Basidiomycota) were the dominant genera associated with the alga. The surface washing/sterilization schemes of algal thalli affected fungal diversity, but the isolation media used did not. While these genera are known producers of antimicrobial secondary metabolites, they might form a mutualistic relationship with P. capillacea by exchanging nutrients from photosynthesis for protection from microbial diseases.

Pterocladiella capillacea–Stabilized Silver Nanoparticles as a Green Approach toward Antibacterial Biomaterials

Silver nanoparticles (AgNPs) synthesized with aqueous extracts of Pterocladiella capillacea presented antibacterial activity against Staphylococcus aureus. AgNPs preparation was optimized, leading to elongated spheres with mean diameter of 17.42 nm....