Search Results (3)

Temperature increase is one of the main effects of climate change occurring worldwide, with drastic impacts on both terrestrial and aquatic biota. Changes in the dominant macroalgal taxa in the Venice Lagoon have been analyzed in relation to the rise in air temperature recorded since 1973, highlighting the significant decline in cold-adapted species, which have been replaced by taxa more tolerant of higher temperatures. Cold-adapted species such as the native Fucus virsoides, Punctaria latifolia, Scytosiphon lomentaria, and many other Phaeophyceae are in decline, whereas thermophilic species such as the non-indigenous species (NIS) Gracilaria vermiculophylla, Agardhiella subulata, Solieria filiformis, Hypnea cervicornis, Caulacanthus okamurae, and many others have replaced the species that once dominated the lagoon. These changes have been associated with an average air temperature increase of approximately 2.5 °C. The highest increase has mostly been recorded for average minimum temperatures (+2.8 °C), compared to average maximum temperatures (+2.0 °C). As a result, Phaeophyceae have declined, while Rhodophyceae, especially recent NIS introductions, have colonized the lagoon bottoms. Changes in Chlorophyceae, on the other hand, appear to be more linked to the reduction of the lagoon’s trophic conditions, although the currently dominant species is Ulva australis, a NIS that has replaced the native Ulva rigida almost everywhere. Full article

To create carbon efficient sources of bioenergy feedstocks and feedstuff for aquaculture and terrestrial livestock, it is critical to develop and commercialize the most efficient seaweed cultivation approach with a sustainable nutrient input supply. Here, we present data for a novel, onshore tropical macroalgae cultivation system, based on influent deep seawater as the nutrient and carbon sources. Two red algal species were selected, Agardhiella subulata and Halymenia hawaiiana, as the basis for growth optimization. Highest productivity in small-scale cultivation was demonstrated with A. subulata in the 10% deep seawater (64.7 µg N L⁻¹) treatment, growing at up to 26% specific growth rate day⁻¹ with highest yields observed at 247.5 g m⁻² day⁻¹ fresh weight. The highest yields for H. hawaiiana were measured with the addition of 10% deep seawater up to 8.8% specific growth rate day⁻¹ and yields at 63.3 g fresh weight m⁻² day⁻¹ equivalent. Biomass should be culled weekly or biweekly to avoid density limitations, which likely contributed to a decrease in SGR over time. With a measured 30–40% carbon content of the ash-free dry weight (20–30% of the dry weight) biomass, this translates to an almost 1:1 CO₂ capture to biomass ratio. The compositional fingerprint of the high carbohydrate content of both Agardhiella and Halymenia makes for an attractive feedstock for downstream biorefinery applications. By focusing on scaling and optimizing seaweed farming technologies for large-scale onshore farms, the opportunities for yield potential, adaptability to cultivation conditions, and meeting global sustainability goals through novel, carbon-negative biomass sources such as seaweed can be realized. Full article

Sulfated polysaccharides from marine macroalgae have been shown to possess a variety of biological activities against fungi, bacteria, viruses, and protozoa. In this study, the in vitro activity of algal polysaccharides against Leishmania infantum (Kinetoplastida: Trypanosomatidae) was investigated. The polysaccharides were extracted from different macroalgae of the Mediterranean Sea: Chaetomorpha linum, Agardhiella subulata, Gracilaria viridis, Gracilaria bursa-pastoris, Hypnea cornuta, Sargassum muticum, and Undaria pinnatifida. Preliminary results showed a good anti-leishmanial activity of the investigated species, encouraging the focus on their use as natural resources in order to match integrated management strategies for the employment of local macroalgae. Full article