John Huisman

The poorly known Western Australian species of the red algal genera Callithamnion Lyngb. and Corynospora J.Agardh (Ceramiales) described by William Henry Harvey in his seminal 1855 paper are reassessed based on morphological and molecular analyses of original and recent collections. Several generic reassignments are proposed, including Desikacharyella australis (Harv.) Huisman, Verbr. & G.W.Saunders (for Corynospora australis Harv.), Guiryella gracilis (Harv.) Huisman, Verbr. & G.W.Saunders (for Corynospora gracilis Harv.), Anotrichium flabelligerum (Harv.) Huisman, Verbr. & G.W.Saunders (for Callithamnion flabelligerum Harv.), Pleonosporium perpusillum (P.C.Silva) Huisman, Verbr. & G.W.Saunders and Pleonosporium crispulum (Harv.) Huisman, Verbr. & G.W.Saunders (for Callithamnion perpusillum P.C.Silva and Callithamnion crispulum Harv.), Aglaothamnion scopula (Harv.) Huisman, Verbr. & G.W.Saunders (for Callithamnion scopula Harv.) and the elevation of Anotrichium thyrsigerum (Harv.) Huisman, Verbr. & G.W.Saunders (for Callithamnion thyrsigerum Harv., previously treated as a variety or synonym of Anotrichium tenue (C.Agardh) Nägeli) to species level. In addition, Callithamnion cliftonii Huisman, Verbr. & G.W.Saunders is proposed as a replacement name for the illegitimate Callithamnion multifidum Harv. and this, and Callithamnion debile Harv., are retained in the genus. Two new species, Ptilothamnion harveyanum Huisman, Verbr. & G.W.Saunders and Seirospora decipiens Huisman, Verbr. & G.W.Saunders, are described from recent collections.

Molecular analyses (rbcL, COI-5P) of Australian specimens that had previously been identified as Hypnea musciformis based on morphology have revealed that this entity is not that species but rather represents an undescribed cryptic species that is here named Hypnea decipiens sp. nov. The new species is known from south-western and southern Australia, north to the Houtman Abrolhos (Geraldton region) of Western Australia and east to the Eyre Peninsula, South Australia. Plants can be locally common in the shallow subtidal and grow to 14 cm in height, with upper branches terminated by crozier-like hooks. Vegetative, cystocarpic and tetrasporangial plants are known, with the zonate tetrasporangia arising in nemathecia at the basal or median sections of lateral branchlets. Despite the morphological similarities, in phylogenetical analyses H. decipiens did not group with the H. musciformis complex (H. musciformis, H. pseudomusciformis, H. caraibica, H. schneideri), but rather was sister to the South African H. rosea. An additional new species, H. subramentacea sp. nov. is described for specimens from south-western Australia that were sister to the common H. ramentacea.

The characteristics of detached macroalgae (drift) in nearby highly eutrophic and mesotrophic estuaries in south-western Australia are compared to elucidate the magnitude and types of changes that occur in macroalgal drift when estuaries receive excessive nutrient input. Drift characteristics in the large basins of the microtidal, eutrophic Peel-Harvey and mesotrophic Swan-Canning, which is not subjected to large nutrient inputs directly from agricultural land, differed markedly. Biomass (dry weight) in mesotrophic estuary was dominated by rhodophytes (92%), particularly Laurencia and Hypnea, and in eutrophic estuary by opportunistic chlorophytes (68%), especially Chaetomorpha and Ulva. Prevalence and biomass of drift were far greater in the eutrophic estuary, particularly during summer and autumn when macroalgal growth rose sharply. Macroalgal biomass in the eutrophic estuary was positively related to salinity. These results facilitate predictions of how climatic and other anthropogenic changes influence extent of macroalgal growth and thus change the estuarine environment.

Two species of the brown algal genus Rosenvingea are reported from south-west (SW) Australia, including the widely distributed R. orientalis and the new species R. australis Huisman, G.H. Boo et S.M. Boo, sp. nov. Molecular phylogenies of mitochondrial cox3 and plastid psaA unequivocally align the SW Australian R. orientalis with specimens from Vietnam and the species is morphologically consistent throughout its Australian range. Australian specimens of the new species R. australis join with a specimen from New Caledonia and these resolve as a sister species to R. intricata, with levels of pairwise divergence (4.2–4.9% in cox3 and 3.9–4.0% in psaA) comparable to those between other scytosiphonacean species. The new species can be distinguished morphologically by its branch dimensions and the arrangement and size of plurangia, but further studies including molecular analyses of a full range of species and possible morphological variants are needed.

Aim: Biogeographical processes underlying Indo-Pacific biodiversity patterns have been relatively well studied in marine shallow water invertebrates and fishes, but have been explored much less extensively in seaweeds, despite these organisms often displaying markedly different patterns. Using the marine red alga Portieria as a model, we aim to gain understanding of the evolutionary processes generating seaweed biogeographical patterns. Our results will be evaluated and compared with known patterns and processes in animals. Location: Indo-Pacific marine region. Methods: Species diversity estimates were inferred using DNA-based species delimitation methods. Historical biogeographical patterns were inferred based on a six-gene time-calibrated phylogeny, distribution data of 802 specimens, and probabilistic modelling of geographical range evolution. The importance of geographical isolation for speciation was further evaluated by population genetic analyses at the intraspecific level. Results: We delimited 92 candidate species, most with restricted distributions, suggesting low dispersal capacity. Highest species diversity was found in the Indo-Malay Archipelago (IMA). Our phylogeny indicates that Portieria originated during the late Cretaceous in the area that is now the Central Indo-Pacific. The biogeographical history of Portieria includes repeated dispersal events to peripheral regions, followed by long-term persistence and diversification of lineages within those regions, and limited dispersal back to the IMA. Main conclusions: Our results suggest that the long geological history of the IMA played an important role in shaping Portieria diversity. High species richness in the IMA resulted from a combination of speciation at small spatial scales, possibly as a result of increased regional habitat diversity from the Eocene onwards, and species accumulation via dispersal and/or island integration through tectonic movement. Our results are consistent with the biodiversity feedback model, in which biodiversity hotspots act as both "centres of origin" and "centres of accumulation," and corroborate previous findings for invertebrates and fish that there is no single unifying model explaining the biological diversity within the IMA.

Environmental consequences of high productivity piggeries are significant and can result in negative environmental impacts, hence bioremediation techniques (in particular using macroalgae) are therefore of great interest. Here, the growth potential of several freshwater macroalgae in anaerobic digestion piggery effluent (ADPE), their nutrient removal rates and biochemical composition of the biomass were investigated under outdoor climatic conditions. A consortium of two macroalgae, Rhizoclonium sp. and Ulothrix sp. was isolated and could efficiently grow in the ADPE. Maximum ammonium removal rate (30.6 ± 6.50 mg NH4+-N L−1 d−1) was achieved at ADPE concentration equivalent to 248 mgNH4+-N L−1. Mean biomass productivity of 31.1 ± 1.14 g ash-free dry weight (AFDW) m-2 d-1 was achieved. Total carbohydrate and protein contents ranged between 42.8–54.8 and 43.4-45.0% AFDW, respectively, while total lipid content was very low. The study indicates the potential use of this macroalgal consortium for treating ADPE as well as source of animal feed production.

Dredging can have significant impacts on benthic marine organisms through mechanisms such as sedimentation and reduction in light availability as a result of increased suspension of sediments. Phototrophic marine organisms and those with limited mobility are particularly at risk from the effects of dredging. The potential impacts of dredging on benthic species depend on biological processes including feeding mechanism, mobility, life history characteristics (LHCs), stage of development and environmental conditions. Environmental windows (EWs) are a management technique in which dredging activities are permitted during specific periods throughout the year; avoiding periods of increased vulnerability for particular organisms in specific locations. In this review we identify these critical ecological processes for temperate and tropical marine benthic organisms; and examine if EWs could be used to mitigate dredging impacts using Western Australia (WA) as a case study. We examined LHCs for a range of marine taxa and identified, where possible, their vulnerability to dredging. Large gaps in knowledge exist for the timing of LHCs for major species of marine invertebrates, seagrasses and macroalgae, increasing uncertainty around their vulnerability to an increase in suspended sediments or light attenuation. We conclude that there is currently insufficient scientific basis to justify the adoption of generic EWs for dredging operations in WA for any group of organisms other than corals and possibly for temperate seagrasses. This is due to; 1) the temporal and spatial variation in the timing of known critical life history stages of different species; and 2) our current level of knowledge and understanding of the critical life history stages and characteristics for most taxa and for most areas being largely inadequate to justify any meaningful EW selection. As such, we suggest that EWs are only considered on a case-by-case basis to protect ecologically or economically important species for which sufficient location-specific information is available, with consideration of probable exposures associated with a given mode of dredging.