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As coastal population growth increases globally, effective waste management practices are required to protect biodiversity. Water authorities are under increasing pressure to reduce the impact of sewage effluent discharged into the coastal environment and restore disturbed ecosystems. We review the role of benthic macroalgae as ecosystem engineers and focus particularly on the temperate Australasian fucoid Hormosira banksii as a case study for rocky intertidal restoration efforts. Research focussing on the roles of ecosystem engineers is lagging behind restoration research of ecosystem engineers. As such, management decisions are being made without a sound understanding of the ecology of ecosystem engineers. For successful restoration of rocky intertidal shores it is important that we assess the thresholds of engineering traits (discussed herein) and the environmental conditions under which they are important. [ABSTRACT FROM AUTHOR]

Recruitment is known to influence distributions and abundances of benthic marine organisms. It is therefore important to document patterns of variability in recruitment and how these relate to patterns in established assemblages. This study provides an integrated assessment of the temporal and spatial variation in supply and recruitment of propagules and established populations of several macroalgae. Propagules in water samples from two stages of the incoming tide, recruitment to artificial substrata and percentage cover of species established on the shore were recorded every 2 months from December 1994 to October 1995, in two zones of an intertidal, wave-exposed rocky shore. Variability in recruitment was measured at three spatial scales: 10s cm, 100s cm and 100s m. Availability and recruitment of most taxa were greatest between April and August, although many species had available propagules and recruited throughout the year. Temporal variation in the established assemblages was, however, more species-specific. Differences in established assemblages between zones were reflected in differences in availability and recruitment of propagules between zones. Recruitment could not be predicted directly from supply of propagules, but the two processes were linked. For most species, the greatest variation in recruitment occurred at the smallest spatial scale of 10s cm, although there was also considerable large-scale (between site) variation in recruitment of several species. Results indicate that while pre-and post-settlement mortality are likely to influence macroalgal distribution and abundance, the temporal and spatial variability in supply and recruitment of propagules can explain much of the patchiness in macroalgal assemblages. [Copyright &y& Elsevier]

[Display omitted] • Biomarkers to identify and quantify carbon contributors to sequestration are needed. • Use of complete sets of fatty acid (FA) profiles are novel to biomarker discovery. • XGBoost models of FA profiles discriminated seaweed carbon from other sources. • High predictive accuracies of this biomarker approach may facilitate quantification. • Quantifying seaweed contributions to blue carbon sequestration may soon be feasible. Differentiating between carbon contributors in marine environments is crucial to gaining a deeper understanding of marine carbon sequestration, and some efforts have been made through the application of various approaches. This study proposed a new approach through the use of fatty acid (FA) profiles of six marine macrophytes within three macroalgal lineages, and three coastal angiosperms (mangrove, saltmarsh, and seagrass). We compiled FA profiles (consisting of 84 individuals and 9 classes/groups of FAs) of 544 Australian coastal macrophyte species identified in published reports. The data were gradually screened into three different datasets (full-84FA, reduced-57FA, and reduced-48FA) for analysis to minimise the effects of imbalanced distributions of data on analysis. XGBoost (eXtreme Gradient Boosting) multiclass classification modelling with hyperparameter tuning was applied to reveal the specific FA signatures of each macrophyte lineage. The XGBoost models run across the three datasets generated high model-performance metrics including precision, recall, F-score, and multiclass-AUC, indicating similar performance between the three models with predictive accuracies of 94%, 85%, and 95%, respectively. At the class level, the three models also demonstrated high performance with precision, recall, and F-score values for each lineage above 0.95, except for Rhodophyta, which ranged from around 0.80 to 0.89. Overall, our findings suggest that the XGBoost classifier can reveal the lineage-specific patterns of FAs (carbon-based molecules) that can be implemented to predict and potentially quantify the carbon contributors to marine sediments, and more specifically, to discern macroalgal carbon contributions from those of other coastal macrophytes. [ABSTRACT FROM AUTHOR]

Large-scale seaweed aquaculture in the ocean is being pursued globally as a solution to many contemporary challenges, including climate change, food security, and ecosystem degradation. However, the required development and transformation of marine systems for farming may have unknown implications for sustainability objectives, such as those outlined in the United Nations Sustainable Development Goals (SDGs). The aim of this paper is to outline the opportunities for, and threats from, seaweed farming in the context of sustainability. We synthesise the perspectives of expert stakeholders from multiple sectors through a series of Australian workshops to catalogue the pathways through which seaweed farming may affect sustainability, giving specific focus to the SDGs. In doing so, this study illustrates that seaweed farming has the potential to influence, to some degree, the majority of SDGs, with both positive and negative influences. Indeed, seaweed farming is most likely to benefit progress towards achieving SDGs 2 (Zero Hunger), 8 (Decent Work and Economic Growth), 9 (Industry, Innovation, and Infrastructure), 12 (Sustainable Production and Consumption), and 15 (Life on Land). But expectations of seaweed farming may also fall short for supporting some goals if appropriate measures are not implemented to mitigate potential impacts, most notably SDG 14 (Life Below Water). We underscore that seaweed farming has the potential to contribute to sustainable development, and that this potential can only be realised with appropriate regulation and mitigation to avoid unwanted negative outcomes. Better identification and management of trade-offs between these potential positive and negative outcomes across sustainability domains, will be critical for realising the full potential of seaweed aquaculture for sustainable development. [ABSTRACT FROM AUTHOR]

Capreolia is a monospecific genus of gelidioid red algae and has been considered to be endemic to Australasia. This is the first report on the occurrence of Capreolia implexa outside of Australasian waters, based on investigations of fresh collections in southern Chile as well as Australia and New Zealand. Thalli are prostrate and form entangled turfs, growing on high intertidal rocks at three locations in Chile. Analyses of rbc L and cox 1 revealed that C. implexa was of Australasian origin and also distinct from its relatives. Analyses of 1356 bp of cox 1 revealed cryptic diversity, consisting of two genealogical groups within C. implexa ; one present in Australia and New Zealand, and the other in Chile and Stewart Island, New Zealand. The extremely low genetic diversity found in C. implexa in Chile and the absence of shared haplotypes between Chile and Australasia suggest genetic bottleneck possibly as a result of colonization after dispersal by rafting from Stewart Island, New Zealand to Chile. [ABSTRACT FROM AUTHOR]