Volume 66, Issue 1

Tasmania is an island state in south-eastern Australia that has a long and rich history of seaweed use, research, and development. It is a cool-temperate system with 750 macroalgal species currently described. Tasmanian Aboriginal peoples have lived on this land for at least 40,000 years utilising seaweed as food, shelter, water carriers and medicine, as well as for ceremonial reasons. Modern taxonomic investigations began with French naturalist Jacques-Julien Houtou de La Billardière in 1791, and there are 184 type specimens of seaweeds originating from Tasmania. Ecological and physiological studies of seaweed in Tasmania have focussed on the dominant large brown seaweeds (Laminariales and Fucales) and have contributed significantly to the global understanding of these systems, particularly related to community resilience, seaweed-urchin interactions, their habitat-forming role for other species, responses to global change, and restoration of lost habitat. Ocean warming and changing oceanography have caused a 95% decline in surface canopy cover of Macrocystis pyrifera in eastern Tasmania since the 1950s and led to a focus on restoring these lost forests. Tasmanian seaweed communities have a uniquely high proportion (up to ∼90%) of seaweeds that rely solely on CO 2 for photosynthesis, which has implications for responses to ocean acidification. Tasmania has industries that use brown seaweeds for fucoidan extraction and beach-cast harvest for alginates, fertilisers, and feeds for agriculture. New aquaculture initiatives include integrated multi-trophic aquaculture, offshore kelp mariculture and Asparagopsis cultivation for bioactive products to reduce methane emissions in ruminants, as and the development of unexploited species including Caulerpa spp. for food.

This bionomic study of the detritic bottoms dominated by macroalgae from the south of Mallorca (Balearic Islands, Western Mediterranean) includes a quantitative description of the algal communities found in the area, as well as their bathymetric and geographical distribution. The results presented here are based on data collected in two oceanographic campaigns conducted in July 2012 and September 2014, using a Jennings beam trawl. A hierarchical group average agglomerative clustering, accompanied by the SIMPROF test, allowed the identification of seven different macroalgal communities, of which two are described here for the first time: the Cryptonemia longiarticulata fields and the Maërl beds of indeterminate rhodoliths. Depth and rhodolith abundance were the two main features driving the distribution of these communities. We found that seven species contributed 70% of the similarity between samples (SIMPER test), with the indeterminate species of rhodoliths (23.6%) and the encrusting fleshy red alga, Agissea inamoena (15.6%) being the most important. The methodology used for the sample selection and quantification processes turned out to be very efficient and faster than other methods used for the characterization of macroalgal communities from detritic bottoms, suggesting that this study could serve as a baseline for similar studies and for future management and conservation actions.

We present a three-gene phylogeny, based on nuclear (short fragment of large subunit ribosomal RNA gene, 1150 base pairs), chloroplast (ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit) and mitochondrial (5′ region of the cytochrome oxidase subunit 1) genes, to determine the position of three species, Kallymeniopsis verrucosa , Beringia castanea and Crossocarpus lamuticus in the Gigartinales. These species were placed by Perestenko in the family Crossocarpaceae, a proposal that was not supported by most phycologists. The goal of this project was to resolve the taxonomic position of these three species and answer the question: Is the Crossocarpaceae a separate family? The concatenated multi-gene phylogeny and the individual gene trees show that these algae nest deeply within the family Kallymeniaceae; K . verrucosa and C . lamuticus are most closely related to species referred currently to the genus Erythrophyllum , whereas B . castanea is sister to the recently established Commanderella ruprechtiana . Taking into account the data on morphology, vegetative and reproductive anatomy of different species, we propose to revive the genus Kallymeniopsis with three species and to retain Crossocarpus as a separate genus. Beringia is a separate monotypic genus.

We report the circumtropical dinoflagellate Tripos lanceolatus (Kofoid) F. Gómez from the Colombian Caribbean, provide a new record from the tropical western Pacific off Tonga, and the first record from the Australian sector of the Indian Ocean. We present the first scanning electron micrographs of thecal ornamentation and apical pore structure which show its morphological similarities to T. furca (Ehrenberg) F. Gómez within the subgenus Biceratium . We also report the more widely distributed tropical species T. schroeteri (B. Schröder) F. Gómez from the Colombian Caribbean, and compare it to the first scanning electron micrographs of the morphologically similar T. digitatus (F. Schütt) F. Gómez within the subgenus Archaeceratium .

Nitzschia martiana , recently restored to Homoeocladia (C. Agardh) emend Lobban et Ashworth, has needle-like cells and forms macroscopic colonies that are so distinctive that they have been reported on the basis of light microscopy alone. It is the type species for Homoeocladia , which have long flaps (conopea) arising from the sternum and covering a valve depression. This group has extreme diversity at the ultrastructural level and it would not be surprising to find another similar to H. martiana . However, Nitzschia venerata , sp. nov., is a surprising look-alike found in a coral reef seaweed sample from Saipan, Northern Mariana Islands (Western Pacific Ocean). It was studied with light- and scanning electron microscopy. Attempts to find colonies in live and preserved samples were unsuccessful. It is very long and narrow, with a valve depression like that in conopeate species. However, ultrastructurally it is not conopeate because the long flaps arise from the valve face and grow toward the keel and can therefore be classified as scuta. Although tube formation remains unknown, the extreme length and narrowness of the cells suggest it might occur, so that scientists identifying potential H. martiana should be alert to the possibility that they have N. venerata or some other needle-like Homoeocladia.

Genetic structure analyses have yielded some examples of inconsistencies between genetic and morphological information. Here, eleven nuclear microsatellite markers and mitochondrial haplotypes were used to examine the genetic structure and gene flow among Japanese Undaria pinnatifida populations and the congeneric species U. undarioides and U. peterseniana . Undaria pinnatifida was subdivided into four “Groups” of populations based on Bayesian clustering analysis, Neighbor-net analysis and Principal coordinate analysis (PCoA). Undaria undarioides samples formed a unique Group. In contrast, U. peterseniana samples either grouped with a mixture of U. pinnatifida and U. undarioides clusters or were included within one of the U. pinnatifida clusters. More significantly, Groups of populations shared alleles with geographically adjacent Groups even between different morphospecies. No clear differences between the inter-and intra-specific genetic divergence were observed in either nuclear or mitochondrial markers. As a result, U. undarioides and U. peterseniana were synonymized with U. pinnatifida . Isolation-by-distance suggested the significance of geographical isolation for maintaining the observed divergence.