Academic literature on the topic 'Marine algae as food Australia, Southeastern'

We review and develop conceptual models for the bio-transfer of ciguatoxins in food chains for Platypus Bay and the Great Barrier Reef on the east coast of Australia. Platypus Bay is unique in repeatedly producing ciguateric fishes in Australia, with ciguatoxins produced by benthic dinoflagellates (Gambierdiscus spp.) growing epiphytically on free-living, benthic macroalgae. The Gambierdiscus are consumed by invertebrates living within the macroalgae, which are preyed upon by small carnivorous fishes, which are then preyed upon by Spanish mackerel (Scomberomorus commerson). We hypothesise that Gambierdiscus and/or Fukuyoa species growing on turf algae are the main source of ciguatoxins entering marine food chains to cause ciguatera on the Great Barrier Reef. The abundance of surgeonfish that feed on turf algae may act as a feedback mechanism controlling the flow of ciguatoxins through this marine food chain. If this hypothesis is broadly applicable, then a reduction in herbivory from overharvesting of herbivores could lead to increases in ciguatera by concentrating ciguatoxins through the remaining, smaller population of herbivores. Modelling the dilution of ciguatoxins by somatic growth in Spanish mackerel and coral trout (Plectropomus leopardus) revealed that growth could not significantly reduce the toxicity of fish flesh, except in young fast-growing fishes or legal-sized fishes contaminated with low levels of ciguatoxins. If Spanish mackerel along the east coast of Australia can depurate ciguatoxins, it is most likely with a half-life of ≤1-year. Our review and conceptual models can aid management and research of ciguatera in Australia, and globally.

Spawning of marine invertebrates may be affected by environmental factors (e.g. food availability, environmental stress) or intrinsic factors (e.g. phylogenetic constraints, developmental mode); intrinsic factors may obscure environmental effects. Two-year surveys of gastropod egg mass deposition were conducted at two rocky intertidal sites in south-eastern Australia to test the following hypotheses: (1) temporal patterns of spawning are more similar within taxonomic order than across orders; and (2) species with planktotrophic larvae are more likely to spawn in seasons coinciding with maximum food availability. There were no discernible effects of either order or developmental mode on spawning patterns, suggesting that spawning behaviour is unrelated to taxonomic order or larval food availability. Alternatively, low numbers of species in certain groups may have increased the risk of not detecting significant effects (type II error). Comparisons with anecdotal data from other regions suggest that developmental mode may indeed play a role in marine gastropod spawning. Criteria are provided for future comparative studies, including a direct focus on specific families and the inclusion of similar latitudes and habitats to those used here. Such studies will help to determine the roles of developmental mode, food availability and environmental stress in the evolution of egg mass deposition.

Spawning of marine invertebrates may be affected by environmental factors (e.g. food availability, environmental stress) or intrinsic factors (e.g. phylogenetic constraints, developmental mode); intrinsic factors may obscure environmental effects. Two-year surveys of gastropod egg mass deposition were conducted at two rocky intertidal sites in south-eastern Australia to test the following hypotheses: (1) temporal patterns of spawning are more similar within taxonomic order than across orders; and (2) species with planktotrophic larvae are more likely to spawn in seasons coinciding with maximum food availability. There were no discernible effects of either order or developmental mode on spawning patterns, suggesting that spawning behaviour is unrelated to taxonomic order or larval food availability. Alternatively, low numbers of species in certain groups may have increased the risk of not detecting significant effects (type II error). Comparisons with anecdotal data from other regions suggest that developmental mode may indeed play a role in marine gastropod spawning. Criteria are provided for future comparative studies, including a direct focus on specific families and the inclusion of similar latitudes and habitats to those used here. Such studies will help to determine the roles of developmental mode, food availability and environmental stress in the evolution of egg mass deposition.

Humanity faces the global challenge of safely removing CO2 from the atmosphere to secure a stable climate. Broadly, there are three options: terrestrial, soils and ocean, and coastal blue carbon sinks. Each option has unique characteristics in relation to permanence, leakage, environmental integrity and co-bene?ts. This extended abstract explores opportunities for blue carbon projects and highlights the important role of engineers in advancing the success of these innovative techniques. Examples of blue carbon include salt marshes, mangroves, seagrasses, macro-algae, coral reefs and open-ocean micro-algae. Regional case studies for mangrove rehabilitation and pioneering research in Australia on micro-algae and open-ocean sequestration are also presented. The world’s oceans contain about 90% of the global carbon budget. Nearly half of global primary productivity occurs in the open-ocean; this productivity has been achieved using only 0.05% of the earth’s biomass. Coastal and marine systems are ef?cient at the continuous storage of carbon, retaining it for centuries. Co-bene?ts include coastal protection, ?sh nurseries, marine biodiversity and improved water quality. Blue carbon is therefore not only direct mitigation, but also a major contributor to the adaptation of changing climate, building a more resilient ecology and supporting long-term sustainability, including that of the major carbon-based industries. Engineers are well equipped to lead this blue revolution while working with scientists and carbon professionals. This extended absrtact highlights opportunities for fast-track implementation and the engineering challenges; it draws on case studies to show scaleable solutions for achieving climate and food security.

Seagrasses are a crucial indicator species of coastal marine ecosystems that provide substratum, shelter, and food for epiphytic algae, invertebrates, and fishes. More accurate mapping of seagrasses is essential for their survival as a long-lasting natural resource. Before reflectance spectra could properly be used as remote sensing endmembers, factors that may obscure the detection of reflectance signals must be assessed. The objectives in this study are to determine the influence of (1) epiphytes, (2) water depth, and (3) seagrass genus on the detection of reflectance spectral signals. The results show that epiphytes significantly dampen bottom-type reflectance throughout most of the visible light spectrum, excluding 670–679 nm; the depth does influence reflectance, with the detection of deeper seagrasses being easier, and as the depth increases, only Heterozostera increase in the exact “red edge” wavelength at which there is a rapid change in the near-infrared (NIR) spectrum. These findings helped improve the detection of seagrass endmembers during remote sensing, thereby helping protect the natural resource of seagrasses.

ABSTRACT Free-living forms of crustose coralline algae (rhodoliths) accumulate on shallow-water marine shelves in many regions worldwide. They form their own benthic habitats termed ‘rhodolith beds' and their deposits are well preserved in the rock record. Characteristics of rhodolith deposits can be used to interpret ancient water depths, light levels, and water energies. Accurate paleoceanographic interpretations rely on large-scale, detailed studies of living rhodolith beds, but these studies are scarce. Spencer Gulf in South Australia has the largest living rhodolith beds in southeastern Australia (∼ 3,000 km2). Documentation of these rhodolith deposits includes facies analysis, coralline algal taxonomy, characterization of growth forms and morphometrics, and integration with oceanographic data. Extensive oceanographic data and hydrodynamic modeling enable comparisons between rhodolith morphologies and bottom water energies with unprecedented accuracy. Rhodolith deposits in the gulf are intermixed with carbonate sands and muds under diverse hydrodynamic conditions, with current speeds up to 1.04 m s−1. At least five coralline algal genera construct rhodoliths in Spencer Gulf. Growth forms include fruticose, lumpy, and warty. Rhodolith morphologies imply that water energy is not the only thing affecting rhodolith movement and growth; rhodoliths can also be shifted by fish and invertebrates. Linear regression models in this study evaluate relationships between rhodolith morphometrics (mean diameter, sphericity, and branch density) and maximum bottom water speeds in Spencer Gulf and their results support the idea that water energy is not a major control on rhodolith morphology under these water energy conditions. Previous studies have revealed that the relationship between rhodolith morphologies and water energy levels is complicated and many authors have cautioned to not rely solely on rhodolith morphologies to interpret paleoceanographic conditions. Results of this study demonstrate that accurate paleoceanographic interpretations cannot be made based on rhodolith morphologies alone, but should also include sedimentology, coralline taxonomy, and associated biota.

ABSTRACT Free-living forms of crustose coralline algae (rhodoliths) accumulate on shallow-water marine shelves in many regions worldwide. They form their own benthic habitats termed ‘rhodolith beds' and their deposits are well preserved in the rock record. Characteristics of rhodolith deposits can be used to interpret ancient water depths, light levels, and water energies. Accurate paleoceanographic interpretations rely on large-scale, detailed studies of living rhodolith beds, but these studies are scarce. Spencer Gulf in South Australia has the largest living rhodolith beds in southeastern Australia (∼ 3,000 km2). Documentation of these rhodolith deposits includes facies analysis, coralline algal taxonomy, characterization of growth forms and morphometrics, and integration with oceanographic data. Extensive oceanographic data and hydrodynamic modeling enable comparisons between rhodolith morphologies and bottom water energies with unprecedented accuracy. Rhodolith deposits in the gulf are intermixed with carbonate sands and muds under diverse hydrodynamic conditions, with current speeds up to 1.04 m s−1. At least five coralline algal genera construct rhodoliths in Spencer Gulf. Growth forms include fruticose, lumpy, and warty. Rhodolith morphologies imply that water energy is not the only thing affecting rhodolith movement and growth; rhodoliths can also be shifted by fish and invertebrates. Linear regression models in this study evaluate relationships between rhodolith morphometrics (mean diameter, sphericity, and branch density) and maximum bottom water speeds in Spencer Gulf and their results support the idea that water energy is not a major control on rhodolith morphology under these water energy conditions. Previous studies have revealed that the relationship between rhodolith morphologies and water energy levels is complicated and many authors have cautioned to not rely solely on rhodolith morphologies to interpret paleoceanographic conditions. Results of this study demonstrate that accurate paleoceanographic interpretations cannot be made based on rhodolith morphologies alone, but should also include sedimentology, coralline taxonomy, and associated biota.

Environmental contextKnowledge of the pathways by which arsenic is accumulated and transferred in marine ecosystems is scarce. Molluscs are important keystone organisms providing a link between primary producers (micro and macroalgae) and higher trophic levels such as fish. The present study examines the accumulation and species of arsenic in common bivalve molluscs from south-east Australia to understand the cycling of arsenic in marine food webs. AbstractThe present paper reports the whole-tissue total arsenic concentrations and water-soluble arsenic species in 12 common coastal Australian bivalve mollusc species. Mean arsenic concentrations ranged from 18 to 57 µg g−1 dry mass. Planktivores had significantly less arsenic (20–40 µg g−1; 22 ± 3 µg g−1) than did suspension and deposit feeders (36–57 µg g−1; 43 ± 7 µg g−1), with those associated with fine clay–silt sediments (49 ± 7 µg g−1) having significantly more arsenic than those associated with sand substrates (31 ± 11 µg g−1 ). Most planktivores and suspension feeders had similar arsenic species, with high proportions of arsenobetaine (AB) (64–92 %) and relatively low proportions of other arsenic species (0.55–15.8 %). Lower proportions of AB (13–57 %) and larger proportions of inorganic arsenic (6–7 %) were found in deposit feeders, reflecting increased exposure to inorganic arsenic in sediments. The study indicated that at lower trophic levels, organisms feed on algae and suspended matter containing a range of arsenic species including arsenosugars and AB. The implications for arsenic cycling are that as all bivalve molluscs accumulate AB and are a source of AB in benthic food webs. Because all bivalve molluscs also contained appreciable concentrations of arsenoriboses, precursors are present for the de novo synthesis of AB. As well, deposit feeders have higher proportions of inorganic arsenic that can be metabolised to different end products when ingested by higher trophic organisms

The Tendaguru Beds, southeastern Tanzania, have yielded two palynological assemblages of Kimmeridgian to Tithonian age: (1) the <i>Anapiculatisporites-Densoisporites-Trisaccites</i> assemblage from the Middle Saurian Beds and (2) the <i>Barbatacysta-Pareodinia</i> assemblage from the overlying <i>Smeei</i> Beds. A third assemblage with <i>Rhizophagites</i> and rare angiosperm pollen from the Upper Saurian Beds is contaminated by recent and subrecent material. <br><br> The <i>Anapiculatisporites-Densoisporites-Trisaccites</i> assemblage is characterized by the presence of freshwater algae (<i>Ovoidites</i>), pteridopyhtic-bryophytic spores and gymnosperm (conifer) pollen, with <i>Classopollis</i> as the most abundant element. Among the rare elements of this assemblage is the questionable dinoflagellate <i>Mendicodinium</i>? <i>quadratum</i>, possibly a Kimmeridgian-Tithonian marker. The miospores show palaeobiogeographic links to Southern Gondwana, especially Madagascar, Australia, Argentina and India. Deposition of this assemblage took place in an aquatic environment with strong palynological influx from a terrestrial source and questionable marine influence. <br><br> The <i>Barbatacysta-Pareodinia</i> assemblage contains a considerable number of dinoflagellates suggesting deposition in a marine environment. The terrestrially-derived miospores are impoverished and dominated by conifer pollen, while pteridophytic-bryophytic spores form a very subordinate element or are absent. <br><br> Die Tendaguru-Schichten, Südost-Tansania, haben zwei palynologische Assoziationen, deren Alter als Kimmeridge bis Tithon interpretiert wird, geliefert. Die <i>Anapiculatisporites-Densoisporites-Trisaccites</i>-Assoziation stammt aus den Mittleren Saurierschichten, und die <i>Barbatacysta-Pareodinia</i>-Assoziation charakterisiert die darüberlagernden <i>Smeei</i>-Schichten. Eine dritte Vergesellschaftung mit <i>Rhizophagites</i> und seltenen Angiospermen-Pollen aus den Oberen Saurierschichten ist durch rezentes bis subrezentes Material kontaminiert. <br><br> Die <i>Anapiculatisporites-Densoisporites-Trisaccites</i>-Assoziation ist durch die Anwesenheit von Süßwasser-Algen (<i>Ovoidites</i>), Pteridophyten-Bryophyten-Sporen und Gymnospermen-Pollen (Koniferen) gekennzeichnet mit <i>Classopollis</i> als dem häufigsten Element. Zu den seltenen Elementen dieser Assoziation gehört der fragliche Dinoflagellat <i>Mendicodinium</i>? <i>quadratum</i>, der möglicherweise als leitend für das Kimmeridge-Tithon angesehen werden kann. Die Miosporen zeigen paläobiogeographische Verbindungen nach Südgondwana, besonders nach Madagaskar, Australien, Argentinien und Indien. Das Ablagerungsmilieu dieser Assoziation war aquatisch mit starker Zufuhr von terrigenem Material, während mariner Einfluß fraglich ist. <br><br> Die Dinoflagellaten-führende <i>Barbatacysta-Pareodinia</i>-Assoziation wurde in einem marinen Milieu gebildet, in dem die Zufuhr terrigener Palynomorphe reduziert und im wesentlichen auf Koniferen-Pollen beschränkt war, während Pteridophyten-Bryophyten-Sporen nur sehr untergeordnet vorkommen oder ganz fehlen. <br><br> doi:<a href="http://dx.doi.org/10.1002/mmng.1999.4860020113" target="_blank">10.1002/mmng.1999.4860020113</a>

The growth of Australian snapper (Pagrus auratus)(Bloch and Schneider) fed diets based on different sources of protein was compared. Two commercial diets for other carnivorous species and two experimental diets for snapper were compared. Fishmeal was the predominant source of protein for one experimental diet (60% content), while the other contained only 10% fishmeal with the remainder of the protein sourced from soybean meal and poultry offal meal. Replacement of fishmeal gave a lower growth rate and higher (poorer) apparent food conversion ratio (FCR, weight of feed given/ live weight gain) compared to the fishmeal diet. The growth rate and FCR obtained with the soybean meal and poultry offal meal diet was similar to that of the two commercial diets tested. Fatty acid analysis of the two experimental diets indicated that concentrations of essential fatty acids exceeded those reported to reduce growth of snapper. Concentration of lysine in the experimental diet associated with reduced growth was lower than that in the diet based on fishmeal.

The thesis investigates members of the crustose and largely calcified red algal family Peyssonneliaceae through molecular analyses and anatomical and ultrastructural observations. Mitochondrial CO1 DNA barcoding was implemented, in combination with fine-scale anatomy, to recognise species boundaries and identify complexes of cryptic species. Nuclear and organellar DNA markers were employed to construct a multigene phylogeny for Vanuatu and southern Australian members of the family facilitating the recognition of two undescribed genera Annea and Incendia.

Extending into the Arabian Gulf, Qatar is surrounded by a number of islands mostly scattered by the eastern coastline. With the unique physical characteristics of the Gulf, which is a highly saline sea with high seawater temperatures, there is an urge need to investigate the macroalgae living in such harsh environment. Macroalgae plays an important role in the food web as they are primary producers and providers of food for other organisms. They also provide shelter and habitat in the marine ecosystem for herbivorous fish and other invertebrate animals. Additionally, macroalgae plays an outstanding role in reducing CO2 from the atmosphere and increasing the level of dissolved oxygen in their immediate environment. However, there are few studies on marine macroalgae in Qatar and no previous studies found related to macroalgae from the islands around Qatar. The present work contributes to the macroalgae research by providing the first survey of distribution and diversity of benthic marine macroalgae in islands around Qatar. The marine benthic green, red and brown macroalgae of intertidal and subtidal in marine zone areas around Qatar were collected during Qatar’s Islands project, which started 2018. The collected macroalgae are documented and a total of 67 species of macroalgae are recorded for all islands around Qatar, 24 Chlorophyta (Green algae), 25 Rhodophyta (Red algae) and 18 species Phaeophyta (Brown algae). The Red algae are dominant taxon in term of species richness, accounting for an average of 37% of the species at all study sites. The islands which had more species are Al-Beshaireya 58 Species, Al-Aaliya 53 Species, Sheraouh 48 Species, Janan 43 Species and Bu Felaita 37 Species. Our results show that islands located at eastern and southeastern coast of Qatar have more diversity of algae species than those located at the western and northwestern coast.